Добірка наукової літератури з теми "Retards de transport"
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Статті в журналах з теми "Retards de transport":
1
Liu, Dan, and Ling-Qiang Zhu. "P3-224: GSK-3 activation retards the axonal transport." Alzheimer's & Dementia 7 (July 2011): S587. http://dx.doi.org/10.1016/j.jalz.2011.05.1666.
2
Chen, Ru, James C. McWilliams, and Lionel Renault. "Momentum Governors of California Undercurrent Transport." Journal of Physical Oceanography 51, no. 9 (September 2021): 2915–32. http://dx.doi.org/10.1175/jpo-d-20-0234.1.
Анотація:
AbstractThe California Undercurrent (CUC) transport, with significant variability ranging from weeks to decades, has consequences for both the climate and biogeochemistry of the California Current system. This study evaluates the governors of the CUC transport and its temporal variability from a momentum perspective, using a mesoscale-resolving regional model. From a 16-yr mean perspective, the along-isobath pressure gradient acts to accelerate the CUC, whereas eddy advection retards it. The topographic form stress, which is part of the volume integrated along-isobath pressure gradient, not only acts in the direction of the time-mean CUC, but also greatly modulates the temporal variability of the CUC transport. This temporal variability is also correlated with the eddy momentum advection. The eddy stress plays a role in transferring both the equatorward wind stress and poleward CUC momentum downward. A theory is formulated to show that, in addition to the conventional vertical redistribution of momentum, the eddy stress can also redistribute momentum horizontally in the area where the correlation between the pressure anomaly and isopycnal fluctuations has large spatial variability.
3
Friederich, E., H. J. Fritz, and W. B. Huttner. "Inhibition of tyrosine sulfation in the trans-Golgi retards the transport of a constitutively secreted protein to the cell surface." Journal of Cell Biology 107, no. 5 (November 1, 1988): 1655–67. http://dx.doi.org/10.1083/jcb.107.5.1655.
Анотація:
The effect of tyrosine sulfation on the transport of a constitutively secreted protein, yolk protein 2 (YP2) of Drosophila melanogaster, to the cell surface was investigated after expression of YP2 in mouse fibroblasts. Inhibition of YP2 sulfation was achieved by two distinct approaches. First, the single site of sulfation in YP2, tyrosine 172, was changed to phenylalanine by oligonucleotide-directed mutagenesis. Second, L cell clones stably expressing YP2 were treated with chlorate, a reversible inhibitor of sulfation. Pulse-chase experiments with transfected L cell clones showed that the half-time of transport from the rough endoplasmic reticulum to the cell surface of the unsulfated mutant YP2 and the unsulfated wild-type YP2 produced in the presence of chlorate was 15-18 min slower than that of the sulfated wild-type YP2. Control experiments indicated (a) that the tyrosine to phenylalanine change itself did not affect YP2 transport, (b) that the retardation of YP2 transport by chlorate occurred only with sulfatable but not with unsulfatable YP2, (c) that the transport difference between wild-type and mutant YP2 was not due to the level of YP2 expression, and (d) that transport of the endogenous secretory protein fibronectin was the same in L cell clones expressing wild-type and mutant YP2. Since the half-time of transport of wild-type YP2 from the intracellular site of sulfation, the trans-Golgi, to the cell surface was found to be 10 min, the 15-18-min retardation seen upon inhibition of tyrosine sulfation reflected a two- to threefold increase in the half-time of trans-Golgi to cell surface transport, which was most probably caused by an increased residence time of unsulfated YP2 in the trans-Golgi. The results demonstrate a role of tyrosine sulfation in the intracellular transport of a constitutively secreted protein.
4
Ebneth, A., R. Godemann, K. Stamer, S. Illenberger, B. Trinczek, E. M. Mandelkow, and E. Mandelkow. "Overexpression of Tau Protein Inhibits Kinesin-dependent Trafficking of Vesicles, Mitochondria, and Endoplasmic Reticulum: Implications for Alzheimer's Disease." Journal of Cell Biology 143, no. 3 (November 2, 1998): 777–94. http://dx.doi.org/10.1083/jcb.143.3.777.
Анотація:
The neuronal microtubule-associated protein tau plays an important role in establishing cell polarity by stabilizing axonal microtubules that serve as tracks for motor-protein–driven transport processes. To investigate the role of tau in intracellular transport, we studied the effects of tau expression in stably transfected CHO cells and differentiated neuroblastoma N2a cells. Tau causes a change in cell shape, retards cell growth, and dramatically alters the distribution of various organelles, known to be transported via microtubule-dependent motor proteins. Mitochondria fail to be transported to peripheral cell compartments and cluster in the vicinity of the microtubule-organizing center. The endoplasmic reticulum becomes less dense and no longer extends to the cell periphery. In differentiated N2a cells, the overexpression of tau leads to the disappearance of mitochondria from the neurites. These effects are caused by tau's binding to microtubules and slowing down intracellular transport by preferential impairment of plus-end–directed transport mediated by kinesin-like motor proteins. Since in Alzheimer's disease tau protein is elevated and mislocalized, these observations point to a possible cause for the gradual degeneration of neurons.
5
Blostein, Rhoda, and Eva Grafova. "Characteristics of membrane transport losses during reticulocyte maturation." Biochemistry and Cell Biology 65, no. 10 (October 1, 1987): 869–75. http://dx.doi.org/10.1139/o87-113.
Анотація:
The decline in activity of distinct membrane transport systems was followed during in vitro maturation of sheep reticulocytes, namely the sodium pump (measured as specific ouabain binding sites), Na+–glycine cotransport, and the nucleoside transporter (measured as specific nitrobenzylthioinosine binding sites). Certain features of this maturation-associated decline in membrane transport are clarified. Thus, the apparent retardation of loss by metabolic (ATP) depletion, reported previously for the sodium pump and Na+–glycine cotransport, is applicable also to the decline in nucleoside transport. The absolute losses, as well as relative effects of ATP depletion, are different for the three distinct systems. Inhibitors of membrane recycling and (or) intracellular processing, such as chloroquine, as well as ATP depletion, prevent not only the loss but also cause a transient increase in nucleoside transport sites apparent at the surface. Proteolytic processing, at least in the case of the nucleoside transporter, is probably also involved since leupeptin retards the loss in binding sites. Protection against the decline in transporters can also be affected by specific ligands as evidenced in ouabain protection of sodium pump sites. The results provide evidence that membrane transporter recycling is a fundamental process underlying the energy-dependent, maturation-associated loss in membrane transport functions.
6
Nicot, Benjamin, Jean-Pierre Korb, Isabelle Jolivet, Hervé Vezin, Didier Gourier, and Anne-Laure Rollet. "Magnetic expression in kerogen reveals impact on fluid transport." Magnetic Resonance 3, no. 2 (July 29, 2022): 125–36. http://dx.doi.org/10.5194/mr-3-125-2022.
Анотація:
Abstract. How can the transport of fluids in a confined and complex mixed organic/inorganic matrix be far below the expected value from a topological aspect? A good example of this situation is oil shales. Oil and gas shales are source rocks in which organic matter has matured to form hydrocarbons. They exhibit a dual porous network formed by the intertwining of mineral and organic pores that leads to very low permeability. Still, the exact origin of this extremely low permeability remains somehow unclear. The present communication addresses this important question and provides novel insights on the mechanisms that strongly hinder fluid diffusion in such materials. By combining nuclear and electronic magnetic resonance techniques with SEM imaging, we show evidence that magnetic interaction occurs in kerogen. This results from a magnetic coupling between vanadyl present in porphyrins and the organic matrix. We demonstrate that such coupling retards fluid diffusion and is reversible. This key dynamical feature explains the extremely low mobility of oil in shale rocks. This phenomenon may be a more general feature occurring in several systems where fluids are confined in a complex hierarchical matrix that embeds both organic and inorganic radicals resulting from the aging process.
7
Casirola, D. M., B. Rifkin, W. Tsai, and R. P. Ferraris. "Adaptations of intestinal nutrient transport to chronic caloric restriction in mice." American Journal of Physiology-Gastrointestinal and Liver Physiology 271, no. 1 (July 1, 1996): G192—G200. http://dx.doi.org/10.1152/ajpgi.1996.271.1.g192.
Анотація:
Lifelong caloric restriction increases median and maximum life span and retards the aging process in many organ systems of rodents. Because the small intestine absorbs a reduced amount of nutrients each day, does lifelong caloric restriction induce adaptations in intestinal nutrient transport? We initially compared intestinal transport of sugars and amino acids between 24-mo-old mice allowed free access to food [ad libitum (AL)] and those provided a calorically restricted [40% less than ad libitum (CR)] diet since 3 mo of age. We found that CR mice had significantly greater transport rates for D-glucose, D-fructose, and several amino acids and had significantly lower villus heights. Total intestinal absorptive capacities for D-glucose, D-fructose, and L-proline were each 40-50% greater in CR mice; absorptive capacity normalized to metabolic mass (body weight 0.75) was approximately 80% greater in CR mice. Comparison of uptakes in aged AL and CR mice with previously published results in young AL mice suggests that caloric restriction delays age-related decreases in nutrient transport. In contrast to published studies in hibernation and starvation, chronic caloric restriction enhances not only uptake per milligram but also uptake per centimeter. We then switched 24-mo-old AL mice to a calorie-restricted diet for 1 mo and found that short-term caloric restriction has no effect on intestinal nutrient transport, intestinal mass, and total absorptive capacity. Thus chronic but not short-term caloric restriction increases intestinal nutrient transport rates in aged mice, and the main mechanism underlying these increases is enhanced transport rates per unit intestinal tissue weight.
8
Zhu, Qinzhang, Michael Lindenbaum, Françoise Levavasseur, Hélène Jacomy та Jean-Pierre Julien. "Disruption of the NF-H Gene Increases Axonal Microtubule Content and Velocity of Neurofilament Transport: Relief of Axonopathy Resulting from the Toxin β,β′-Iminodipropionitrile". Journal of Cell Biology 143, № 1 (5 жовтня 1998): 183–93. http://dx.doi.org/10.1083/jcb.143.1.183.
Анотація:
To investigate the role of the neurofilament heavy (NF-H) subunit in neuronal function, we generated mice bearing a targeted disruption of the gene coding for the NF-H subunit. Surprisingly, the lack of NF-H subunits had little effect on axonal calibers and electron microscopy revealed no significant changes in the number and packing density of neurofilaments made up of only the neurofilament light (NF-L) and neurofilament medium (NF-M) subunits. However, our analysis of NF-H knockout mice revealed an ∼2.4-fold increase of microtubule density in their large ventral root axons. This finding was further corroborated by a corresponding increase in the ratio of assembled tubulin to NF-L protein in insoluble cytoskeletal preparations from the sciatic nerve. Axonal transport studies carried out by the injection of [35S]methionine into spinal cord revealed an increased transport velocity of newly synthesized NF-L and NF-M proteins in motor axons of NF-H knockout mice. When treated with β,β′-iminodipropionitrile (IDPN), a neurotoxin that segregates microtubules and retards neurofilament transport, mice heterozygous or homozygous for the NF-H null mutation did not develop neurofilamentous swellings in motor neurons, unlike normal mouse littermates. These results indicate that the NF-H subunit is a key mediator of IDPN-induced axonopathy.
9
Fiermonte, G., J. E. Walker, and F. Palmieri. "Abundant bacterial expression and reconstitution of an intrinsic membrane-transport protein from bovine mitochondria." Biochemical Journal 294, no. 1 (August 15, 1993): 293–99. http://dx.doi.org/10.1042/bj2940293.
Анотація:
The oxoglutarate carrier, an intrinsic membrane-transport protein of the inner membranes of bovine-heart mitochondria, has been expressed at an abundant level in Escherichia coli. It accumulates in the bacterium as inclusion bodies, and none of the protein was detected in the bacterial inner membrane. The mitochondrial ADP/ATP carrier, a member of the same super-family of transport proteins as the oxoglutarate carrier, has also been expressed in E. coli. However, the expression of the ADP/ATP carrier in bacteria retards their growth, and so the levels of expression that were attained were lower than those of the oxoglutarate carrier. The oxoglutarate carrier inclusion bodies have been disaggregated with the detergent N-dodecanoyl-sarcosine, and the protein has been incorporated into liposomes. In its ability to transport oxoglutarate and malate and other known substrates of the carrier in mitochondria, and in its inhibition characteristics by a wide range of non-competitive and competitive inhibitors, this reconstituted oxoglutarate carrier is similar to the natural protein in the inner membranes of mitochondria, and to the carrier that has been purified from mitochondria and reconstituted in liposomes. These experiments remove significant obstacles to crystallization trials and to site-directed mutagenesis of the oxoglutarate carrier.
10
Yang, Y. Q., and J. T. Wu. "RU 486 interferes with egg transport and retards the in vivo and in vitro development of mouse embryos." Contraception 41, no. 5 (May 1990): 551–56. http://dx.doi.org/10.1016/0010-7824(90)90063-2.
Дисертації з теми "Retards de transport":
1
Pujo-Menjouet, Laurent. "Contribution à l'étude d'une équation de transport à retards décrivant une dynamique de population cellulaire." Phd thesis, Université de Pau et des Pays de l'Adour, 2001. http://tel.archives-ouvertes.fr/tel-00001176.
Анотація:
Nous présentons un modèle de division de cellules sanguines basé sur la présence d'un facteur appelé maturation et le partage du cycle en une phase de prolifération et une phase de repos. Il est représenté par un système S de deux équations de transport structuré en âge et maturité. En intégrant par rapport à l'âge, S devient un système d'équations aux dérivées partielles à retards structuré en maturité. Dans le chapitre 1, nous introduisons le contexte biologique, et nous présentons notre modèle. Dans le chapitre 2, nous étudions le modèle quand la phase de prolifération est fixe et la division est égale. Nous montrons l'existence et l'unicité puis un résultat liant les solutions aux cellules souches ainsi qu'un résultat d'invariance, de comportement asymptotique et d'instabilité. Dans le chapitre 3, nous supposons que la phase de prolifération varie suivant la maturité des cellules. Nous prouvons des résultats analogues au chapitre 2. Dans le chapitre 4, la phase de prolifération est fixe mais nous supposons la division inégale. En utilisant la théorie des opérateurs de Markov, nous prouvons un résultat de stabilité globale.
2
Nouasse, Houda. "Gestion supervisée de systèmes étendus à retards variables : cas des réseaux hydrographiques." Thesis, Toulouse, INPT, 2015. http://www.theses.fr/2015INPT0001/document.
Анотація:
De part et d’autre de la Terre, on observe de plus en plus de phénomènes naturels dévastateurs, parmi lesquels les inondations constituent l’une des catastrophes les plus fréquentes. Ces dernières décennies d’importantes inondations ont été induites par les crues de rivières. Ces crues, dues à des pluies excessives ou aux eaux de ruissellement, causent sans cesse des pertes de vies humaines et des dégâts matériels importants. Pour remédier à ces problèmes, les réseaux hydrographiques sont de plus en plus équipés de moyens de détection de crues. Un facteur essentiel à la gestion de tels phénomènes est la réactivité. En effet, les gestionnaires des réseaux hydrographiques, dans ce genre de situation, doivent prendre rapidement des décisions importantes dans un contexte incertain, car la plupart de ces crues sont le fruit de phénomènes climatiques brusques, dont l’ampleur est difficile à évaluer avec précision. Nous proposons, dans ce mémoire, une méthode de gestion des crues dans des réseaux hydrographiques équipés de zones inondables contrôlées par des portes gravitationnelles. Dans un premier temps, nous avons modélisé notre méthode de gestion à l’aide d’un réseau de transport statique. Dans un second temps, nous l’avons enrichi en utilisant les réseaux de transport à retards dans le but de prendre en compte les temps de déplacement de la ressource gérée. Afin de pallier le problème de la taille importante des réseaux de transport à retards, nous avons élaboré un mécanisme de substitution combinant un réseau de transport statique réduit et une matrice de temporisation. De plus, ce mécanisme autorise la prise en compte des temps de transfert variables dépendant des débits, sans modification ni du réseau de transport, ni de la structure de la matrice de temporisation. Ce mécanisme permet donc une gestion simplifiée des temps de transferts, variables ou non. Avec ce mécanisme, l’évaluation du flot maximal à coût minimum, nous a permis, suivant les stratégies de gestion considérées, de consigner l’ouverture des portes des zones inondables afin d’écrêter la crue mais aussi afin de restituer cette eau stockée au moment opportun. Finalement, afin d’évaluer les apports de cette gestion, la méthode a été appliquée sur un cas d’étude basée sur un tronçon de rivière équipé de trois zones inondables et modélisé à l’aide de simulateurs hydrauliques combinant les approches de modélisation 1D et 2D. Les résultats de simulation obtenus ont montré que l’approche proposée permettait de réduire de manière significative les inondations en aval des cours d’eauOn either side of the Earth, we observe more and more devastating natural phenomena. Amon these phenomena, floods are one of the most frequent and devastating natural disasters. During these last decades extensive flooding were caused by the flood of rivers. These floods due to excessive rainfall or runoff induce invariably the loss of human lives and material damages. To overcome these problems, water systems are increasingly equipped with means for detecting floods. A key factor in the management of such phenomena is responsiveness. Indeed, managers of river systems, faced to this kind of situation should quickly take important decisions in an uncertain context, as most of these floods are induced by abrupt climate events, whose magnitude is difficult to assess accuracy. We propose in this dissertation, a method of flood management in river systems equipped with flood zones controlled by gravitational gates. At first, we modeled our management method using a static transportation network. In a second step, we enriched it by using transportation networks with delays in order to take into account the travel time of the managed resource. The main difficulty of transportation networks with delays is their oversize. To overcome this problem, we developed an alternative mechanism combining a static reduced transportation network with a temporization matrix. Furthermore, this mechanism allows the consideration of variable time transfer depending on flows, without modification either on the transportation network, or on the structure of the temporization matrix. This mechanism allows simplified management of the transfer times, variable or not. With this mechanism, the evaluation of the minimum cost maximum flow allowed us, according to the management strategies considered, to compute the gate opening for floodplains in order to mitigate the flood but also to restore the water stored at the relevant time. Finally, to evaluate the contributions of this management, the method was applied to a case study based on a section of river equipped with three flood control reservoirs areas modeled using hydraulic simulators combining 1D and 2D models. The simulation results showed that the proposed approach allowed reducing significantly the floods downstream watercourses
3
RABIN, OLIVIER. "Approches physiologiques et physiopathologiques des transports hematoencephalique : caracterisation et regulation du transport du manganese; alteration du transport des acides amines au cours du retard de croissance intra-uterine." Paris 7, 1992. http://www.theses.fr/1992PA077164.
Анотація:
La barriere hematoencephalique (bhe), constituee par les cellules endotheliales des capillaires sanguins cerebraux, est une structure restrictive au passage des substances du compartiment plasmatique vers le cerveau. Les recherches menees ont permis de mieux comprendre le role de la bhe au cours du retard de croissance intra-uterine (un modele de sous-nutrition), et de montrer que cette structure n'est pas impliquee dans les modifications cerebrales observees au cours de cette pathologie. Au contraire la bhe apparaitrait comme un element de protection du cerveau permettant de preserver la croissance et le fonctionnement cerebral. Les caracteristiques du transport hematoencephalique du manganese ont egalement ete etudiees, ainsi que leur regulation par les proteines plasmatiques et les autres metaux lourds essentiels ou toxiques. Ces travaux sont discutes sous les aspects physiologique du metabolisme cerebral, mais egalement sous des considerations neurotoxiques
4
Cai, Jianru. "Le transport multimodal : étude comparée de droit chinois et de droit français." Thesis, Paris 1, 2018. http://www.theses.fr/2018PA01D048.
Анотація:
Le transport multimodal n'est pas nouveau. Lieux de production et de consommation étant souvent éloignés, qui plus est dans une économie toujours davantage internationalisée, l'acheminement de la marchandise soulève inévitablement le recours à ce type de transport-ci. Le transport maritime, tout comme le transport ferroviaire et aérien, requiert nécessairement un pré-acheminement et/ou un post-acheminement. Seul le transport routier pourrait échapper à ces contraintes. Pourtant, «le transport multimodal» est un concept juridique de création moderne. On parlait auparavant de «transport combin», «transport mixte» ou encore «transport multimodal transimaritime» suite à l'initiative de Monsieur le Professeur Pierre BONASSIES et désormais il est fait référence au «transport international», «transport multimodal». L'originalité du transport multimodal a pour conséquence de soulever un certain nombre de problèmes juridiques touchant la responsabilité, l'assurance, la compétence juridictionnelle. Cette thèse tente de répondre aux difficultés juridiques relatives à ce mode de transport. Il s'agit notamment de deux questions fondamentales : la première question est de déterminer la responsabilité de l'entrepreneur du transport multimodal et sa limitation de responsabilité. La deuxième question est de savoir quelle est la loi applicable en cas de conflit de lois et l'influence des Règles de Rotterdam. Cela notamment au regard de « la commission de transport » qui, si le concept est reconnu largement dans tous les pays, ne dispose néanmoins pas du même statut juridique. Le droit français distingue la notion de «commissionnaire» de celle de «transitaire». Le «Non-Vessel-Operation Common Carrier» (NVOCC) est un peu l'adaptation internationale de la notion française de commissionnaire de transport. Après les États-Unis et les Philippines, la Chine a récemment adopté la notion de NVOCC dans les «Modalités d'application du Règlement de la République populaire de Chine aux transports maritimes internationaux». Ce problème renvoie aux questions d'identification de transporteur et de sa limitation de responsabilitéNo English summary available
5
Citolleux, Marie-Rose. "La responsabilité du transporteur routier international pour perte, avarie, ou retard selon la convention de Genève du 19 mai 1956 (C. M. R. ) : étude comparée des droits français, allemand, autrichien et suisse." Paris 1, 1996. http://www.theses.fr/1996PA010286.
Анотація:
L'étude de l'application de la convention CMR du 19 mai 1956 en France, Allemagne, Autriche et Suisse relative à la responsabilité du transporteur routier pour perte, avarie ou retard, montre que son évolution a été complexe. Même si en général l'application dans les quatre pays fait ressortir que les solutions jurisprudentielles sont homogènes, il existe encore un peu moins de dix points qui sont interprétés différemment par les tribunaux. Ces points concernent aussi bien la détermination de la responsabilité que la mise en oeuvre de cette responsabilité. Les différences mettent en valeur que l'interprétation française est toujours plus sévère que celle des autres pays et que le transporteur poursuivi devant les juridictions françaises aura un traitement moins favorable que celui poursuivi en Allemagne, Autriche ou SuisseThe study of the application of the CMR convention, 19 may 1956, in France, Germany, Austria and Switzerland concerning the liability of the road carrier for loss, damage or for delay in the delivery, shows that the evolution has been complex. Eventhough the application of the four different countries shows that in general the solution of case law is uniform there remains still less than ten points which are differently interpretated by the courts. Those points concern the determination of the liability as well as the implementation of this liability. The differences of interpretations bring out that the French interpretation is always stronger than that of the other countries and that the carrier sued in front of the French courts will have a less favourable treatment compared to a carrier sued in Germany, Austria or Switzerland
6
Bezerra, Rufino Ferreira Paiva Eduardo. "Wind Velocity Estimation for Wind Farms." Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLM046.
Анотація:
Cette thèse propose des algorithmes pour estimer la vitesse et la direction du vent pour des éoliennes et des parcs éoliens.Tout d'abord, nous proposons des méthodes basées sur les données pour estimer la vitesse effective du rotor (REWS) sans nécessiter la connaissance de certains paramètres physiques de l'éolienne, qui pourraient être inconnus de l'opérateur. Nous fournissons deux méthodes basées sur les données, l'une basée sur la régression par processus gaussien et l'autre combinant la régression par processus gaussien avec un observateur grand gain.Ensuite, en nous basant sur cette estimation locale de la REWS, au niveau d'une éolinenne, nous abordons la question de l'estimation du vent en écoulement libre au niveau du parc éolien.Nous commençons par nous concentrer sur l'estimation de la vitesse du vent, pour une direction du vent connue. Pour un parc éolien de géométrie simple, nous démontrons qu'une mesure locale de la vitesse perturbée par la présence des éoliennes peut être utilisée pour estimer la vitesse du vent en écoulement libre. Nous fondons notre méthodologie d'estimation sur une modélisation simplifiée de l'effet de sillage qui consiste en des équations aux dérivées partielles hyperboliques du premier ordre en cascade, et dont la vitesse de transport est la vitesse du vent en écoulement libre. Nous proposons d'utiliser une solution analytique de ces équations, impliquant des retards de transport, pour effectuer une estimation de la mesure locale et mettre à jour l'estimation de la vitesse du vent en écoulement libre. Nous démontrons formellement la convergence de cette estimation et illustrons numériquement l'efficacité de cette méthode.Enfin, nous passons à une configuration plus générale où à la fois la vitesse et la direction du vent en écoulement libre sont inconnues. Nous proposons d'utiliser une modélisation bidimensionelle du sillage et de nous appuyer sur une méthode basée sur l'optimisation. Le problème d'identification que nous formulons se révèle être particulièrement difficile en raison de l'apparition de retards de transport, mais nous montrons comment contourner cette difficulté en considérant une valeur moyenne de l'historique de la vitesse du vent en écoulement libre. Des résultats de simulation obtenus avec le simulateur FAST.Farm illustrent l'intérêt de la méthode proposéeThis thesis designs algorithms to estimate the wind speed and direction for wind turbines and wind farms.First, we propose data-based methods to estimate the Rotor Effective Wind Speed (REWS) for a single turbine without prior knowledge of certain physical parameters of the turbine that might be unknown to an operator.We provide two data-based methods, based respectively on Gaussian Process Regression (GPR) and on an combination of GPR with high-gain observers.Second, grounding on this REWS estimation at the local level of one turbine, we address the question of estimating the free-flow wind at the level of a wind farm.We start by focusing on wind speed estimation, for a given known wind direction. For a wind farm with a simple geometry, we prove that a local speed measurement disturbed by the presence of the turbines can be used to estimate the free-flow wind speed. We ground our estimation methodology on a simplified wake model, which consists of first-order hyperbolic partial differential equations, the transport speed of which is the free-flow wind speed. We propose to use an analytical solution of these equations, involving transport delays, to perform an estimate of the local measurement and to update the free-flow wind speed estimate. We formally prove the convergence of this estimate and numerically illustrate the efficiency of this method.Finally, we move to a more general setup where both the free-flow wind speed and direction are unknown. We propose to use a two-dimensional wake model and to rely on an optimization-based method. This identification problem reveals to be particularly challenging due to the appearance of transport delays, but we illustrate how to circumvent this issue by considering an average value of the free flow wind speed history. Simulation results obtained with the simulator FAST.Farm illustrate the interest of the proposed method
7
Wang, Chunan. "Essays on Delay Reduction Contract, Airline Networks and Agricultural Land Marketization." Thesis, Toulouse 1, 2017. http://www.theses.fr/2017TOU10024/document.
Анотація:
Cette thèse se compose de trois articles autonomes, dont chacun correspond à un chapitre. Le premier chapitre, écrit conjointement avec Estelle Malavolti, étudie la conception optimale du contrat de réduction des retards signé entre un ANSP et une compagnie aérienne monopoliste. Dans la conception du contrat, nous considérons principalement le problème d’antisélection. En outre, nous effectuons une analyse comparatif-statique pour étudier les effets de la norme de sécurité et de la fréquence de vol sur les contrats optimaux. A la fin, nous utilisons des exemples numériques pour étudier le cas où un ANSP maximisant son bien-être doit utiliser des fonds publics pour fournir le service. Le deuxième chapitre étudie le double rôle des retards de congestion et de la différenciation horizontale des produits dans le choix du réseau aérien. Je trouve que, premièrement, en raison de l’inclusion des retards de congestion, la compagnie aérienne peut choisir le réseau point à point lorsque la désutilité des services avec une escale, engendrée par le temps supplémentaire du voyage, est relativement faible. Deuxièmement, sans tenir compte des investissements fixes de la compagnie aérienne dans le développement d’un aéroport de hub, le réseau 2-hub dominera les trois autres structures de réseau aussi longtemps que cela sera possible, car il implique la différenciation horizontale des produits sur plus de marchés que les trois autres structures de réseau. Le troisième chapitre, écrit conjointement avec Wanjun Yao et Shigeyuki Hamori, trouve empiriquement que l’efficacité de l’allocation des terres plus élevée améliore la productivité des terres moyenne de 29,1% et la plus grande taille de la ferme opérationnelle moyenne réduit la productivité des terres moyenne de 9,2%, ce qui implique que la commercialisation des terres agricoles en Chine améliore finalement la productivité des terres moyenne de 19,9%This thesis consists of three self-contained papers, each of which corresponds to one chapter. The first chapter, jointly written with Estelle Malavolti, studies the optimal design of delay reduction contract signed between an ANSP and a monopoly airline. In the contract design, we mainly consider the adverse selection problem. Moreover, we conduct comparative-static analysis to study the effects of safety standard and flight frequency on optimal contracts. Besides, we use numerical examples to study when a welfare-maximizing ANSP has to use public funds to provide the service. The second chapter investigates the dual roles of congestion delays and horizontal product differentiation in airline network choice. I find that, first, because of the inclusion of congestion delays, the airline may choose the point-to-point network even when the extra travel time disutility of one-stop services is relatively low. Second, without considering the airline's fixed investments of developing a hub airport, the 2-hub network will dominate the three other network structures as long as it is feasible, as it involves the horizontal product differentiation in more markets than the three other network structures. The third chapter, jointly written with Wanjun Yao and Shigeyuki Hamori, empirically finds that the higher land allocation efficiency improves the average land productivity by 29.1% and the larger average operational farm size reduces the average land productivity by 9.2%, implying that the agricultural land marketization in China finally improves the average land productivity by 19.9%
8
Godoy, Vanessa Almeida de. "Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-13072018-092153/.
Анотація:
Numerical models are becoming fundamental tools to predict a range of complex problems faced by geotechnical and geo-environmental engineers. However, to render the model reliable for future predictions, the model input parameters must be determined with consideration of the scale effects. If there is a difference of scales between the observation and the model scales there are two possible ways to consider it: or models are constructed with elements of a size similar to that at which the data were measured, or some upscaling rules must be defined. In this context, this thesis focuses on upscaling of water flow and mass transport in a tropical soil by means of numerical, laboratory and field studies. This thesis is organized in four parts. First, the heterogeneity, correlation and cross-correlation between solute transport parameters (dispersivity, α, and partition coefficient, Kd) and soil properties are studied in detail. In this part, it is verified that the hydraulic conductivity (K) and solute transport parameters are highly heterogeneous, while soil properties are not. Spatial correlation of α, K, and statistically significant variables are studied, and it would probably improve the estimation only in a small-scale study, since the spatial correlation are only observed up to 2.5 m. This study is a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the one that should be included in future studies. In the second part, scale effect on K, dispersivity and partition coefficient of potassium and chloride are studied experimentally by means of laboratory and field experiments. The purpose is to contribute to the discussion about scale effects on K, α and Kd and understanding how these parameters behave with the change in the scale of measurement. Results show that K values increases with scale, regardless of the method of measurement, except for the results obtained from double-ring infiltrometer tests. Dispersivity trends to increase exponentially with the sample height. Partition coefficient tends to increase with sample length, diameter and volume. These differences in the parameters according to the scale of measurement must be considered when these observations are later used as input to numerical models, otherwise the responses can be misrepresented. Third, stochastic analysis of three-dimensional hydraulic conductivity upscaling is performed using a simple average and the Laplacian-with-skin methods for a variety of block sizes based on real K measurements. In this part it is demonstrated the errors that can be introduced by using a deterministic upscaling using simple averages of the measured K without accounting for the spatial correlation. Results show that K heterogeneity can be incorporated in the daily practice of the geotechnical modeler. The aspects to consider when performing the upscaling are also discussed. Finally, the dependence of the exponent of the p-norm as a function of the block size is analyzed. In the last part, stochastic upscaling of hydrodynamic dispersion coefficient (D) and retardation factor (R) is performed using real data aiming to reduce the lack in experimental upscaling of reactive solute transport research. The enhanced macrodispersion coefficient approach is used to upscale the local scale hydrodynamic dispersion (D) and, as a novelty, the impact of heterogeneity of local dispersivity is also taken into account. To upscale retardation factor (R), a p-norm is used to compute an equivalent R. Uncertainty analyses are also performed and a good propagation of the uncertainties is achieved after upscaling. Simple upscaling methods can be incorporated to the modeling practice using commercial transport codes and properly reproduce de transport at coarse scale but may require corrections to reduce smoothing of the heterogeneity caused by the upscaling procedure.Modelos numéricos estão se tornando ferramentas fundamentais para prever uma série de problemas complexos enfrentados por engenheiros geotécnicos e geoambientais. No entanto, para que o modelo seja confiável para previsões futuras, seus parâmetros de entrada devem ser determinados com a consideração do efeito da escala. Se há uma diferença de escalas entre a escala da observação e a escala do modelo, existem duas maneiras possíveis de considerá-la: ou constrói-se modelos com elementos de tamanhos semelhantes àqueles em que os dados foram medidos, ou definem-se algumas regras de mudança de escala. Neste contexto, esta tese enfoca a mudança de escala do fluxo de água e do transporte de massa em um solo tropical, por meio de estudos numéricos, laboratoriais e de campo. Esta tese é organizada em quatro partes. Em primeiro lugar, estudou-se em detalhe a heterogeneidade, a correlação e a correlação cruzada entre os parâmetros de transporte de soluto (dispersividade, α, e coeficiente de partição, Kd) e as propriedades do solo. Nesta parte, verificou-se que a condutividade hidráulica (K) e os parâmetros de transporte de soluto são altamente heterogêneos, enquanto as propriedades do solo não o são. A correlação espacial de α, K e das variáveis estatisticamente significativas foi estudada, e, provavelmente, melhoraria a estimativa apenas em um estudo em pequena escala, uma vez que a correlação espacial só foi observada até 2,5 m. Este estudo foi uma primeira tentativa de avaliar a variação espacial no coeficiente de correlação dos parâmetros de transporte de um soluto reativo e não-reativo, indicando as variáveis mais relevantes e as que devem ser incluídas em estudos futuros. Na segunda parte, o efeito de escala em K, na dispersividade e no coeficiente de partição de potássio e cloreto é estudado experimentalmente por meio de ensaios laboratoriais e de campo. O objetivo foi contribuir com a discussão sobre os efeitos de escala em K, α e Kd e entender como esses parâmetros se comportam com a mudança na escala da medição. Os resultados mostram que K aumenta com a escala, independentemente do método de medição. A dispersão tende a aumentar de maneira exponencial com a altura da amostra. O coeficiente de partição tende a aumentar tanto com o comprimento, quanto com o diâmetro e o volume da amostra. Essas diferenças nos parâmetros de acordo com a escala de medida devem ser consideradas quando essas observações são posteriormente usadas como entrada para modelos numéricos, caso contrário, as respostas podem ser mal representadas. Em terceiro lugar, uma análise estocástica tridimensional da mudança de escala da condutividade hidráulica foi realizada usando tanto média simples quanto o método Laplaciano-com-pele para vários tamanhos de blocos usando medidas K reais. Nesta parte, foram demonstrados os erros que podem ser introduzidos ao se usar métodos determinísticos de mudança de escala, usando médias simples das medições de K sem se considerar a correlação espacial. A aplicação das técnicas de mudança de escala mostra que a heterogeneidade de K pode ser incorporada na prática diária do modelador geotécnico. Os aspectos a serem considerados ao realizar a mudança de escala também foram discutidos. Finalmente, analisou-se a dependência do expoente da norma p em função do tamanho do bloco. Na última parte, uma aplicação de mudança de escala estocástica do coeficiente de dispersão hidrodinâmica (D) e do fator de retardo (R) foi realizada usando dados reais visando reduzir a falta pesquisas no tema de mudança de escala do transporte de soluto reativo. A mudança de escala do D foi feito usando o método de macrodispersão. O método da média simples baseado na norma p foi usado para executar a mudança de escala de R. A incerteza foi propagada satisfatoriamente. Métodos simples de mudança de escala podem ser incorporados à prática de modelagem usando programas comerciais, e reproduzir corretamente o transporte em escala grossa, mas podem exigir correções para reduzir o efeito suavizado da heterogeneidade causada pelo procedimento de mudança de escala.
9
Letrouit, Vincent. "Optimisation du réseau des routes aériennes en Europe." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0141.
Анотація:
Le reseau aerien actuel est compose d'un ensemble de segments qui s'intersectent en des points particuliers definis par des balises emettant des signaux a partir du sol. Ce reseau conduit a un exces des distances parcourues par les avions estime a 8% en europe. Or il est desormais possible grace aux systemes de type gps de concevoir un nouveau reseau independant de moyens au sol. Dans ces conditions, un nouveau reseau aerien pourrait integrer d'une part des lignes aeriennes en ligne droite entre les aeroports et d'autre part la possibilite donnee aux avions de changer de niveau une ou plusieurs fois entre l'origine et la destination en des points pre-definis, afin d'eviter les points de conflit potentiel. Dans cette these, nous presentons principalement des problemes combinatoires sur les ensembles de segments, lies a la conception d'un reseau de ce type. Nous proposons des heuristiques pour le probleme de la clique maximum, de la coloration, de la coloration avec n couleurs d'un ensemble de segments, et un algorithme pour la coloration des segments par portion avec 2 couleurs. Nous proposons ensuite des indicateurs tres simplifies nous permettant d'evaluer facilement la charge de l'espace aerien et la quantite de conflits generees par le deplacement des avions sur nos reseaux. Dans ce cadre, nous effectuons une modelisation des retards au decollage par une loi log-normale et nous adaptons un modele de conflit existant. Finalement, nous donnons des resultats sur des donnees reelles du trafic aerien europeen representant jusqu'a 50% des flux.
10
Zamoum, Redouane. "Etude théorique des fluctuations de courant de l'admittance et de la densité d'états d'un nano-système en interaction." Phd thesis, Aix-Marseille Université, 2013. http://tel.archives-ouvertes.fr/tel-00881571.
Анотація:
Dans notre thèse nous nous sommes intéressés à l'étude des fluctuations de courant, de l'admittance quantique ainsi que la densité d'états pour un nano système en interaction. Notre travail se divise en deux parties. Dans la première partie, nous avons étudié les fluctuations de courant et l'admittance pour un conducteur unidimensionnel, en décrivant le système par un liquide de Tomonaga-Luttinger. Nous avons utilisé les techniques de bosonisation et de refermionisation afin d'aboutir à des résultats exacts pour tous les régimes de température, toutes les valeurs de la tension appliquée et toute la gamme des fréquences. Les résultats obtenus sont appliqués à un conducteur cohérent couplé à un quantum de résistance, et aux états de bord dans le régime de l'effet Hall quantique fractionnaire. Dans le cas d'un conducteur cohérent, le bruit non symétrisé à fréquence finie exhibe un profil différent de celui de la théorie de la diffusion, et la conductance à fréquence finie est directement liée au courant. Dans le cas du régime de l'effet Hall quantique fractionnaire, nous avons pu établir que dans certaines limites, il existe une relation entre les corrélations de courant à l'admittance quantique. En particulier, les singularités qui apparaissent dans les corrélations de courant sont celles de l'admittance. Dans la deuxième partie, nous avons étudié un fil quantique connecté à deux réservoirs qui sont représentés par deux impuretés. Le système est décrit par un liquide de Tomonaga-Luttinger. Nous avons établi et résolu l'équation de Dyson pour la fonction de Green retardée. Ce qui permet de calculer la densité d'états pour un fil quantique homogène puis inhomogène. Dans le cas d'un paramètre d'interaction homogène, l'effet des impuretés modifie le profil de la densité d'états. Dans le cas d'un paramètre d'interaction inhomogène, le calcul de la densité d'états est plus difficile et une approche numérique est indispensable.
Книги з теми "Retards de transport":
1
Freeman, Richard R., James A. King, and Gregory P. Lafyatis. Electromagnetic Radiation. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198726500.001.0001.
Анотація:
Electromagnetic Radiation is a graduate level book on classical electrodynamics with a strong emphasis on radiation. This book is meant to quickly and efficiently introduce students to the electromagnetic radiation science essential to a practicing physicist. While a major focus is on light and its interactions, topics in radio frequency radiation, x-rays, and beyond are also treated. Special emphasis is placed on applications, with many exercises and homework problems. The format of the book is designed to convey the basic concepts of a topic in the main central text in the book in a mathematically rigorous manner, but with detailed derivations routinely relegated to the accompanying side notes or end of chapter “Discussions.” The book is composed of four parts: Part I is a review of basic E&M, and assumes the reader has a had a good upper division undergraduate course, and while it offers a concise review of topics covered in such a course, it does not treat any given topic in detail; specifically electro- and magnetostatics. Part II addresses the origins of radiation in terms of time variations of charge and current densities within the source, and presents Jefimenko’s field equations as derived from retarded potentials. Part III introduces special relativity and its deep connection to Maxwell’s equations, together with an introduction to relativistic field theory, as well as the relativistic treatment of radiation from an arbitrarily accelerating charge. A highlight of this part is a chapter on the still partially unresolved problem of radiation reaction on an accelerating charge. Part IV treats the practical problems of electromagnetic radiation interacting with matter, with chapters on energy transport, scattering, diffraction and finally an illuminating, application-oriented treatment of fields in confined environments.
Частини книг з теми "Retards de transport":
1
Nagy, Endre. "Pressure-Retarded Osmosis (PRO) Process." In Basic Equations of Mass Transport Through a Membrane Layer, 505–31. Elsevier, 2019. http://dx.doi.org/10.1016/b978-0-12-813722-2.00021-2.
2
Su, Jincai, and Tai-Shung Chung. "Membrane Distillation, Forward Osmosis, and Pressure-Retarded Osmosis Through Polymer Membranes." In Transport Properties of Polymeric Membranes, 323–46. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-809884-4.00016-1.
3
Anand, Lallit, and Sanjay Govindjee. "Small deformation theory of species diffusion coupled to elasticity." In Continuum Mechanics of Solids, 286–98. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198864721.003.0015.
Анотація:
This chapter presents a coupled theory for transport of a single atomic (or molecular) chemical species through a solid that deforms elastically. Consideration is limited to isothermal conditions and circumstances in which the deformations are small and elastic, and the changes in species concentration from a reference concentration are small --- a framework known as the theory of linear chemoelasticity. Underlying the presented approach is the notion that the solid can deform elastically but it retains its connectivity and does not itself diffuse. To account for the energy flow due to species transport, the notion of chemical potential of the species is introduced. First the basic equations of the fully-coupled linear theory of anisotropic linear chemoelasticity are derived, and then these equations are specialized for the case of isotropic materials.
4
Cheng, Zhen Lei. "Mass Transport within Pressure Retarded Osmosis Membranes of Different Configurations." In Membrane Technology for Osmotic Power Generation by Pressure Retarded Osmosis, 63–102. CRC Press, 2020. http://dx.doi.org/10.1201/9780429288562-4.
5
Alberto De La Riva De La Riva, Gustavo, Luis Adrián Saldaña Trujillo, and Juan Carlos González-Hernández. "Assessment on Oxidative Stress in Animals: From Experimental Models to Animal Production." In Importance of Oxidative Stress and Antioxidant System in Health and Disease [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.109043.
Анотація:
Oxygen is a key element involved in a variety of vital physiological reactions in aerobic organisms, including those produced in the electron transport chain, hydroxylation, and oxygenation. Reactive oxygen species and reactive oxygen nitrogen species (ROS/RONS) are naturally formed as by-products from these previously mentioned processes and reactions involving the O2 molecules. Under healthy conditions, the harmful effects of ROS/RONS in the organisms are controlled by antioxidants, molecules of enzymatic or non-enzymatic nature, able to prevent, retard, or eliminate oxidative damage. Nevertheless, when ROS/RONS production exceeds the antioxidant capacity of one organism, oxidative stress emerges, leading to the apparition of many diseases, some of which can depict significant losses in the field of animal production. Thereby, looking for increasing animal productivity, procedures to mitigate the effects of oxidative stress on living organisms are tested in laboratory animal models, and the obtained results are used to develop strategies that avoid oxidative stress in farm animals either invertebrates (mollusks and crustacean species) or vertebrates (fish, birds, and mammals). In this chapter, oxidative stress will be addressed from the field of animal health and welfare and its impact on animal production, presenting some strategies, studies conducted, and recent perspectives to mitigate the effects of oxidative stress and improve the productivity indicators in farm animals.
6
Hagel, Lars. "Separation on the basis of chemistry." In Protein Purification Techniques. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780199636747.003.0011.
Анотація:
Most chromatographic separations are based on chemical interaction between the solute of interest or impurities to be removed and the separation medium. The exception is separations based upon physical properties such as size (e.g. size exclusion chromatography) or transport in a force field (e.g. electrochromatography). The chemical interaction may be weak (e.g. employing van der Waals forces) or very strong (e.g. involving formation of chemical bonds as in covalent chromatography). Whenever separation is based upon attractive forces between the solute and the separation medium, we talk about adsorption chromatography (also when the solute is merely retarded). The chemical interaction between the solute and the adsorbent (the chromatography medium) is governed by the surface properties of the solute and the adsorbent and is in most cases mediated by the mobile phase or additives to the mobile phase. Macromolecules such as proteins display a variety of properties and, ideally, a selected set of properties is utilized for obtaining the required selectivity (i.e. relative separation from other solutes) using a separation medium of complementary properties. This chapter briefly reviews the different types of forces of interaction between solutes and surfaces commonly employed for chromatographic purifications, important properties of solvents, and some basic surface chemical properties of proteins. This, together with a description of some common types of chromatography modes provides a basis for a rational selection of separation mechanism for the purification of proteins and the choice of mobile phase composition to regulate the relative influence of different interaction mechanisms. The separation mechanisms are focused to adsorptive modes with the exception of affinity chromatography which is discussed in Chapter 9. The different attractive forces acting between molecular and particle surfaces include (1): • dispersion forces • electrostatic dipole interactions • electron donor-acceptor forces • formation of covalent bonds All these forces are due to interactions between electric charges (permanent or induced). Dispersion, or London forces, are caused by induced dipole-induced dipole interactions and are thus classified as a non-specific interaction. This type of non-polar interaction is the dominant force promoting dissolution of non-polar solutes in organic solvents.
7
Hope, Geoffrey. "The Quaternary in Southeast Asia." In The Physical Geography of Southeast Asia. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199248025.003.0012.
Анотація:
We live in the Quaternary period and are a product of its wide fluctuations in climate and rapid environmental change. From at least the Mid-Miocene, about 25 million years ago, the expansion of the Southern Ocean has supported a powerful westerly wind system. These winds prevent tropical heat from reaching the Antarctic region, which in turn has allowed the gradual refrigeration of the world’s oceans as ice built up on Antarctica (and eventually formed an ice shelf over the sea; Nunn 1999). Earlier in the Tertiary, when the ocean column was warm from top to bottom, seasonal cooling was offset by rising warm water, and the ocean currents effectively transported heat to the poles. For the last 2 million years the main mass of the oceans has remained at maximum density, around 4°C, with warmer surface waters of the tropical and temperate regions floating only in the upper few hundred metres above the thermocline. The Quaternary is the period of refrigerated ocean which marks an ice age, with the Earth in such a delicate thermal equilibrium that relatively minor changes in the amount of solar radiation received by a given hemisphere in a given season cause major fluctuations of ice volume in terrestrial ice caps. The marked asymmetry of land and sea in the two hemispheres means that the effects of changes in the season of closest approach to the sun, of the degree of tilt of the planet and the eccentricity of the orbit, cause instability in the long-term climate. The Quaternary is defined by successive expansions and retreats of ice caps, with the maximum episodes of ice and of warmth (the interstadials) each lasting around 10 000 years. Intermediate times are cooler than present, and these persist for around 100 000 years. The lock-up of ice is reflected by global changes in sea level, ocean levels falling about 125 m during glacial maxima and rising up to 6 m above present during some interglacials. The Antarctic ice cap retains about 75 m of the ocean’s water even during the interglacial phases.
Тези доповідей конференцій з теми "Retards de transport":
1
Ghanbari, S., E. J. Mackay, T. Clemens, W. Hujer, A. Rath, M. R. Lüftenegger, M. Magdalena, and A. Zamolyi. "Geochemical Reactivity Modelling During CO2 Induced Convective Brine Mixing." In SPE Europe Energy Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/220161-ms.
Анотація:
Abstract OMV is planning to store CO2 in a depleted gas field located in Eastern Europe. Within the storage site, the rock assemblage contains several minerals which may react with CO2. Although such mineral dissolution could be locally limited, those reactions may be enhanced by the CO2 triggered convective flow patterns acting to provide a continuous unsaturated water supply at the CO2/water interface affecting the integrity of the storage site. Using the field observed mineralogy, batch and reactive transport models were constructed to provide understanding about the characteristics of mineral dissolutions in the storage site. Batch modelling was undertaken to understand the most significant reacting minerals. 1D modelling captured key characteristics of mineral dissolution within the reactive system under forced carbonated water flow. 2D modelling was used to analyse the mineral dissolution profile at and below the CO2/water interface for a range of permeability conditions. Learnings were applied to a full field 3D model, enabling understanding of the significance of convective flow patterns on mineral dissolution at the field scale. Batch modelling results showed only carbonate minerals are susceptible to reaction with carbonated water; other minerals could thus be discarded from further reaction transport modelling. 2D modelling results identified an interesting and previously unreported feature of temporary calcite dissolution/precipitation within the storage site. It was observed that at favourable permeabilities, dissolved calcite mineral within the CO2 plume region will slump along with the carbonated water, and subsequently reprecipitate immediately beneath the CO2/water interface to form a temporary dense calcite region. This denser accumulation of calcite is, nevertheless, dissolved in the long-term by the effect of the convective flow patterns. 2D modelling results also showed that under natural flux of convective formation water triggered by CO2 dissolution, mineral dissolution will be insufficient to affect storage site integrity. Finally, results of 3D modelling showed that within the target storage site, the impact of convective flow patterns is not expected to be significant enough to trigger extensive geochemical reactions and integrity issues. This is due to the relatively low permeability of the storage site, which retards the formation of strong convective flow patterns below the CO2/water interface. Mineral dissolution is locally limited and does not represent a major risk to storage security. This study illustrates the impact of convective flow patterns when evaluating the integrity of CO2 storage prospects. Although such geochemical reactions may be assumed to be locally limited, they could be promoted by the supply of continuous water triggered by convective flow patterns. This feature is important in integrity modelling studies, and the impact of continuous water supply on the extent of long-term geochemical reactions should be correctly taken into account.
2
Briones Delgado, Alan, Ramon Martín de Pozuelo, Guiomar Corral Torruella, Agustín Zaballos Diego, and Guillermo Dobao Lázaro. "Mecanismos de nivel de transporte para la optimización de envíos sobre Long Fat Networks." In XIII Jornadas de Ingenieria Telematica - JITEL2017. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/jitel2017.2017.6514.
Анотація:
Este artículo investiga los mecanismos de diferentes protocolos de transporte en transferencias sobre redes de alta capacidad y alto retardo, conocidas como Long Fat Networks (LFNs) para un envío eficiente de los datos. Transport Control Protocol (TCP) presenta limitaciones de rendimiento y flexibilidad. En la literatura se pueden encontrar diferentes propuestas de variantes del comportamiento de TCP, protocolos como Stream Control Transmission Protocol (STCP) o soluciones que proporcionan una comunicación confiable y mecanismos de control de congestión sobre User Datagram Protocol (UDP). En este artículo se presentan una serie de mecanismos de nivel de transporte para la optimización de transferencias de datos sobre redes LFN. Estos mecanismos ofrecen un rendimiento elevado utilizando todo el ancho de banda disponible del enlace mediante un proceso de cálculo del estado de la red y un control de congestión activo para la utilización de todo el bandwidth, a la vez que reactivo en caso de producirse pérdidas para evitar congestiones en la red. El objetivo es demostrar la eficiencia de dichos mecanismos, así como su adaptabilidad y aggressive friendliness respecto a otros protocolos de transporte mediante el despliegue de una serie de pruebas expuestas en este artículo.
3
Wake, Amanda K., Geeta Datta, Mayakonda N. Palgunachari, Vinod K. Mishra, G. M. Anantharamaiah, and C. Roger White. "Apolipoprotein A-I Mimetic Peptide Retains Function After Oxidant Exposure." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-189660.
Анотація:
Mechanical integrity of arteries is vital for maintaining compensatory mechanisms under physiologic conditions, and changes in vessel structure (and consequently, vessel mechanical properties) are hallmarks of the progression of pathologic states. Oxidative stress can (1) induce endothelial dysfunction by interfering with nitric oxide (NO) signaling pathways relevant to vasodilation/vasoconstriction of arteries, and (2) alter atherosclerotic plaque composition by oxidation of constituents or by interruption of reverse cholesterol transport from plaques.
4
Kalabayev, Ruslan, Dmitriy Abdrazakov, Yeltay Juldugulov, Vladimir Stepanov, Denis Emelyanov, Rostislav Romanovskii, and Campbell Kinnear. "Advanced Fracturing Design Simulator-Assisted Modeling Coupled with Application of Enhanced Stimulation Fluids Raises Performance of Acid Fractured Wells." In SPE Europec featured at 82nd EAGE Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205139-ms.
Анотація:
Abstract Important factors affecting acid fracturing efficiency include etched fracture geometry, cleanup, and optimum differential etching to retain open channels after fracture closure. A recently applied integrated approach combined improvements in all three factors: new fracture simulation techniques enabled fracture geometry optimization, single-phase retarded acid provided significant increase in half-length, and high retained permeability viscous fluids supported better fracture cleanup. The approach was successfully implemented in several carbonate oil fields and resulted in a substantial productivity index increase. The approach enables acid fracture optimization in three steps. First, the high retained permeability, low-pH pad fluids and polymer-free leakoff control acids are used in combination to enhance formation cleanup after a treatment and to reduce the concentration of polymers in fissures network of naturally fractured carbonate reservoirs. Second, a new single-phase retarded acid is used to achieve longer half-length due to retarded reaction with formation rock and favorable viscous fingering effects. Third, a new acid fracturing simulation model is used to optimize fracture geometry. The simulation technique employs an innovative transport model that includes the viscous fingering effect, advanced leakoff simulation, changing acid rheology upon spending, and a novel calculation approach to mixed fluids' rheology. This combined concept was applied during acid fracturing treatments in moderate permeability wells of carbonate reservoirs with target intervals up to 4,600 m TVD and temperatures up to 125°C. The treatments consisted of guar-free low-pH pad fluid, polymer-free leakoff control acid, and single-phase retarded acid. Treatment optimization was performed using an advanced acid fracturing simulator to properly address the transport processes within the fracture in a low-stress-contrast environment. After the treatments, the pressure transient analysis indicated a strong linear regime for more than 15 hours, indicating effective fracture half-length at least 25% higher than average half-length after acid fracturing in offset wells where the conventional approach had been applied. Post-treatment half-length calculations showed a good match with advanced simulator results and proved the importance of accounting for viscous fingering effects during acid fracture half-length calculations. Calculation of the productivity index from the production data showed at least 15% increase compared to conventional acid fracturing treatments. The post-fracturing production decline rate was at least 20% slower than that of the conventional treatment in offset wells, which can be explained by the longer conductive fracture.
5
Al-Sabea, Salem Hamad, Abdullah Abu-Eida, Milan Patra, Mohammad Naji AlEidi, Giuseppe Ambrosi, Nakul Khandelwal, Rishika Gaur, Khaled Matar, Abdulatif Al wazzan, and Julio Vasquez. "Low Viscosity Polymer Free Acid Retarded System, a Novel Alternative to Emulsified Acid: Successful Application in West Kuwait Field." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22665-ms.
Анотація:
Abstract Acid systems are widely recognized by the oil and gas industry as an attractive class of fluids for the efficient stimulation of carbonate reservoirs. One of the major challenges in carbonate acidizing treatments is adjusting the convective transport of acid deep into the reservoir while achieving a minimum rock face dissolution. Conventional emulsified acids are hindered by several limitations; low stability at high temperatures, a high viscosity that limits pumping rate due to frictional losses, the potential of formation damage, and the difficulty to achieve homogenous field-scale mixing. This paper highlights the successful application of an engineered low-viscosity retarded acid system without the need for gelation by a polymer or surfactant or emulsification by diesel. An acid stimulation job using a new innovative retarded acid system has been performed in a West Kuwait field well. The proposed acid system combines the use of a strong mineral acid (i.e. hydrochloric acid "HCl") with a non-damaging retarding agent that allows deeper penetration of the live HCl acid into the formation, resulting in a more effective stimulation treatment. The retardation behavior testing includes dissolution experiments, compatibility testing, coreflood study, and corrosion rate testing (conducted at 200°F). The on-job implementation included the use of a packer to pinpoint fluid pumping (pre-flush) at the point of interest, followed by the customized novel retarded acid system for improving conductivity at perforations and effective reservoir stimulation. This acid system is characterized by having a low-viscosity and high thermal stability system that can be mixed on the fly. This approach addresses the main challenges of emulsified acid systems and offers a cost-effective solution to cover a wide range of applications in matrix acid stimulation and high-temperature conditions that require a chemically retarded acid system. The application of this novel acid retarded system is a fit-for-purpose solution to optimize the return on investment by maximizing the well production and extending the lifetime of the treatment effect. This new system also offers excellent scale inhibition and iron control properties which eliminates the need for any acid remedial work, making it an economical approach over other conventional acid systems. The paper presents results obtained after stimulating the carbonate reservoir and describes the lessons learned from the job planning and execution phases, which can be considered as a best practice for application in similar challenges in other fields. Proper candidate selection, best available placement technique, and lab-tested formulation of novel retarded acid system resulted in achieving 1700 BOPD of oil production (27% higher than expected).
6
Zhang, Jin, and Harris Wong. "Evaporation, Condensation, and Flow in an Idealized Micro Heat Pipe." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39196.
Анотація:
Micro heat pipes have been used in cooling micro electronic components. However their effective thermal conductivity is low compared with that of conventional heat pipes. Due to the complexity of the coupled heat and mass transport, and to the complicated three-dimensional bubble geometry inside micro heat pipes, there is a lack of rigorous analysis. As a result, the relatively low effective thermal conductivity remains unexplained. We have conceptualized an idealized micro heat pipe that eliminates the complicated geometry, but retains the essential physics. Given the simplified geometry, many effects can be studied, such as thermocapillary flow, and evaporation and condensation physics. In this talk, we will present the flow field induced by evaporation.
7
Toulouse, Michael M., Guislain Doljac, Van P. Carey, and Cullen Bash. "Exploration of a Potential-Flow-Based Compact Model of Air-Flow Transport in Data Centers." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10806.
Анотація:
This paper summarizes an exploration of a compact model of air flow and transport in data centers developed from potential flow theory. Boundaries for the airflow in the data center are often complex due to the numerous rows of servers and other equipment in the facility, and there are generally multiple air inlets and outlets, which produce a fairly complex three-dimensional flow field in the air space in the data center. The general problem of airflow and convective transport in a data center requires accurate treatment of a turbulent flow in a complex flow passage with some buoyancy effects. As a result, full CFD thermofluidic models tend to be time-consuming and tedious to set up for such complex flow circumstances. In this initial study, we formulated an approximate model that retains only the most basic physical mechanisms of the flow. The resulting model of air flow in the data center is based on potential flow theory, which is exact for irrotational inviscid flow. The temperature field resulting from server heat input is determined by solving the convective energy transport equation along potential flow streamlines. This innovative approach, which takes advantage of the irrotational character of the modeled flow, provides a fast computational method for determining the temperature field and convective transport of thermal energy in the data center. Computations to predict the three-dimensional flow and temperature fields with the model typically require less than 60 seconds to complete on a laptop computer. Flow and temperature field results predicted by the model for typical data center flow circumstances are presented and limitations of the model are assessed. Features of an intuitive graphical user interface for the model that simplifies input of the data center design parameters are also described. Results for case studies indicate low sensitivity to mesh size and convergence criteria. Although the flow and temperature field models developed here are more approximate than full CFD methods, they are good first approximations that provide the means to rapidly explore the parameter space for the data center design. This model can be used to quickly identify the optimal region of the design space, whereupon a more detailed CFD modeling can be used to fine-tune an optimal design. The results of this investigation demonstrate that this type of fast compact model can be a very useful tool when used as a precursor to full CFD modeling in data center design optimization.
8
Yafia, Mohamed, and Homayoun Najjaran. "The Effect of Changing the Gap Height on Droplet Deformation During Transport in Digital Microfluidics Systems." In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21296.
Анотація:
The objective of this paper is to characterize the droplet deformation during transport and to show how the droplet morphology changes at different gap heights in digital microfluidics systems. The aspect ratio defined as the ratio between the gap height to the electrode side length will be varied within the range of high to extremely low. In this way, we will demonstrate that the droplet morphology significantly changes during transport when the aspect ratio is changed. Analogous to the channel dimensions, the gap height and the electrode side length are the two most important geometrical variables affecting droplet motion in digital microfluidic systems. In this study, the droplet deformation was found to be minimal at higher aspect ratios. Contrarily, the droplet will exhibit severe necking and elongation at very low aspect ratios. The deformation and necking patterns were found to be similar to the necking pattern that happens during splitting. However, the droplet exhibits this necking when it is only driven by one activated electrode during the transport process. On the other hand, the droplet is pulled by driving forces from two opposite directions in the conventional splitting process. Extended simulations are performed to investigate the effect of changing the aspect ratio and the actuation voltage used. The simulations were performed by FLOW-3D software which uses the volume of fluid (VOF) technique. The results confirm the effect of changing the gap height on the droplet behavior during motion. The extreme deformation and necking happens only at very low aspect ratios. In this case, the transport process starts by moving a small portion of the droplet toward the activated electrode. When this small portion advances toward the activated electrode the rest of the droplet is not greatly affected or pulled toward the same direction. It can be noticed that the remaining portion of the droplet is not moving at the initial stages of motion and the droplet start to be squeezed gradually through a neck instead of moving in a bulk form. Further observations demonstrated droplet elongation and delayed response of the back portion of the droplet compared to the motion of the leading edge. Analyzing the motion by analytical models can be inaccurate as they assume that the droplet retains its circular shape. Therefore, CFD simulations can demonstrate the droplet behavior better than the analytical models where the droplet exhibits severe deformation and deviation from the circular shape.
9
Chen, Mingpeng, Guanhui Xie, Dongyang Li, and Sichao Tan. "Mixing Characteristic Measurement of Flow in Reactor Pressure Vessel by Laser Induced Fluorescent Method." In 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-65770.
Анотація:
Abstract Under normal conditions, the mixing uniformity of boric acid and coolant in the descending section and the lower chamber of PWR is an important factor affecting the core reactivity distribution. In the emergency shutdown process, the transient dilution of boron may cause secondary criticality. Therefore, the mixing of the de-borated slug with the ambient coolant in the reactor pressure vessel was investigated by using a three-loop 1:6 scaled visualization pressure vessel model with ACP1000 as the prototype device. The pressure vessel model retains the structures related to the experiment, such as the radiation monitoring tube, while the other structures are simplified accordingly. The dye solution was used as the boric acid injection coolant to measure the concentration distribution of dyes on the vertical and different cross sections, and the mixing mechanism was analyzed by LIF. In the slug mixing test, the coolant flow rate and the dye injection flow rate were changed respectively, and the chromatid concentration changes with time and its distribution at different times were detected. The effect of Reynolds number is analyzed. In the descending section, the injection continuously collides with the tube wall and is diluted by the surrounding pure water, the transport of the stain along the annulus boundary and the diffusion on the cross section are weakened, and the transport mainly occurs in the circular direction. After the mixed fluid passes through the lower head and the lower plate of the core, the concentration of the fluid region near the wall is lower, while the concentration in the middle is higher, and the distribution is inverted fan. The related research results of this experiment qualitatively reveal the mudding process of boric acid and deborated coolant before entering the reactor core, quantitatively analyzed the concentration distribution of the observed area.
10
Kalwar, Ankur, Akhilendra Singh, and Avinash Kumar Agarwal. "Potential of Di-Ethyl Ether in Reducing Emissions from Heavy-Duty Tractors." In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0285.
Анотація:
<div class="section abstract"><div class="htmlview paragraph">Considering the demand for sustainable transport, alternative fuels are a keen research topic for IC engine researchers. Among various alternative fuels being explored, Di-ethyl ether (DEE) is gaining popularity off-late for compression-ignition (CI) engines owing to its high cetane rating, oxygen presence in its molecular structure, and lower carbon content. This study explores the suitability of DEE blends in tractor engines. DEE blends [15% and 30% (v/v)] with diesel were compared with baseline diesel for combustion, and emission characterisation, keeping all parameters identical, including the fuel injection timings. Results were analysed for different engine loads at 1500 rpm. Delayed combustion was observed with DEE blends with diesel, possibly due to a higher cooling effect from DEE vaporisation and retarded dynamic fuel injection due to its higher compressibility. However, the DEE blend fuelled engine performance was comparable to baseline diesel. Considerable reductions in NOx and soot emissions were observed with DEE30. Hence, compared to DEE15, DEE30 emerged as a more suitable fuel for heavy-duty tractor engines using a mechanical fuel injection system, exhibiting lower emissions and comparable efficiencies.</div></div>
Звіти організацій з теми "Retards de transport":
1
Viani, B. E. Assessing materials (''Getters'') to immobilize or retard the transport of technetium through the engineered barrier system at the potential Yucca Mountain nuclear waste repository. Office of Scientific and Technical Information (OSTI), March 1999. http://dx.doi.org/10.2172/8325.
2
Thurston, Alison, Zoe Courville, Lauren Farnsworth, Ross Lieblappen, Shelby Rosten, John Fegyveresi, Stacy Doherty, Robert Jones, and Robyn Barbato. Microscale dynamics between dust and microorganisms in alpine snowpack. Engineer Research and Development Center (U.S.), March 2021. http://dx.doi.org/10.21079/11681/40079.
Анотація:
Dust particles carry microbial and chemical signatures from source regions to deposition regions. Dust and its occupying microorganisms are incorporated into, and can alter, snowpack physical properties including snow structure and resultant radiative and mechanical properties that in turn affect larger-scale properties, including surrounding hydrology and maneuverability. Microorganisms attached to deposited dust maintain genetic evidence of source substrates and can be potentially used as bio-sensors. The objective of this study was to investigate the impact of dust-associated microbial deposition on snowpack and microstructure. As part of this effort, we characterized the microbial communities deposited through dust transport, examined dust provenance, and identified the microscale location and fate of dust within a changing snow matrix. We found dust characteristics varied with deposition event and that dust particles were generally embedded in the snow grains, with a small fraction of the dust particles residing on the exterior of the snow matrix. Dust deposition appears to retard expected late season snow grain growth. Both bacteria and fungi were identified in the collected snow samples.
3
Dudoit, Alain. Les espaces européens communs de données : une initiative structurante nécessaire et adaptable au Canada. CIRANO, October 2023. http://dx.doi.org/10.54932/ryht5065.
Анотація:
Le Rapport bourgogne, publié par le CIRANO en juillet 2023, préconise la création d'un espace commun de données dans le corridor commercial stratégique des Grands Lacs et du Saint-Laurent d'ici 2030. Cette proposition s’appuie notamment sur trois rapports distincts de politiques publiés en 2022 par le groupe de travail national sur la chaîne d’approvisionnement, le Conseil des ministres responsables des transports et de la sécurité routière (COMT) et le Comité permanent de la Chambre des communes sur les transports, l'infrastructure et les collectivités. Le constat posé et les recommandations qui découlent de ces rapports soulèvent des questions de fond qui sont au centre des enjeux critiques de gouvernance, de culture d’organisation, de capacité d’exécution, de mobilisation des parties prenantes du public et du privé, ainsi que de la sous-utilisation des données au sein de l’appareil gouvernemental canadien mis à rude épreuve par des années de retard et exacerbée par les perturbations récentes liées à des catastrophes climatiques anticipées. La création d’un espace commun de données est envisagée comme un investissement structurant de l'infrastructure essentielle du Canada pour le transport intermodal et la chaîne d’approvisionnement. Ce document de travail sur les Espaces Européens Communs de Données (EECD) prolonge la synthèse et les recommandations publiées en juillet dernier. Face à l’accélération de l’économique numérique, la gouvernance et le partage efficace des données sont devenus des enjeux fondamentaux pour les politiques publiques à tous les niveaux de juridictions et dans tous domaines de l’activité humaine. Le présent document vise à examiner les initiatives et les défis associés à la gouvernance des données, en mettant particulièrement l'accent sur les Espaces Européens Communs de Données (EECD) et leur pertinence pour le contexte canadien. Il explore la complexité inhérente à la gouvernance des données, qui doit concilier les spécificités sectorielles avec des principes de gouvernance plus universels. Ce faisant, il souligne l'importance d'une action stratégique et coordonnée pour maximiser les avantages sociaux et économiques des données. Le document de travail sur les EECD étend la portée du Rapport bourgogne en fournissant une analyse opérationnelle de l'initiative en cours au sein de l'Union européenne (UE). Celle-ci découle de la stratégie européenne des données de 2020 et vise à établir douze espaces communs de données dans des secteurs stratégiques, y compris la mobilité et les transports. Le document se divise en trois parties principales. La première partie offre un aperçu des politiques publiques relatives aux données au Canada et dans l'UE entre 2018 et 2023. La deuxième partie se concentre sur les implications et les leçons tirées de l'analyse d'impact qui soutient l'adoption de la législation sur la gouvernance des données par les institutions européennes. Cette loi vise à établir un cadre réglementaire pour la création des espaces communs de données en Europe. La troisième partie aborde le déploiement actuel des EECD, en soulignant les étapes clés et les processus en cours. Le document met en évidence des similitudes notables entre l'UE et le Canada en ce qui concerne l'identification des enjeux et la formulation des objectifs de politique publique en matière de données. Il souligne aussi des différences entre ces deux partenaires stratégiques dans l’optimisation du partage des données entre les juridictions et parties prenantes. Ces deux partenaires stratégiques se distinguent cependant par une différence fondamentale: l'absence d'une mutualisation efficace des ressources au sein de l’appareil intergouvernemental canadien dans la poursuite d’objectifs communs face à des enjeux majeurs communs tel celui des données à la grande différence de l’entreprise des EECD par l’UE dans la poursuite d’objectifs identiques de positionnement comme chef de file mondial l’économie des données. Cette absence de considération et, encore moins, d’action conjointe par l’appareil intergouvernemental canadien de mise en œuvre d’une stratégie commune des données au Canada est dommageable. Pour être efficace, la réponse canadienne doit être agile, axée sur les résultats, et intégrée à travers les différentes juridictions. La gestion rigoureuse, l’utilisation responsable et le partage organisé des données au sein et entre les différentes juridictions sont des éléments cruciaux pour aborder les défis complexes et les risques majeurs auxquels le Canada est confronté. Ni le gouvernement fédéral ni ceux des provinces ne sont actuellement bien positionnés pour traiter ensemble les données comme un actif stratégique commun. La résolution des obstacles réglementaires, juridiques et techniques à l'échange de données entre juridictions et organisations nécessite la création d'un espace commun de données qui à son tour implique une combinaison des outils et des infrastructures requises à cette fin, ainsi qu'un traitement des questions de confiance notamment par des règles communes.
4
Kirchhoff, Helmut, and Ziv Reich. Protection of the photosynthetic apparatus during desiccation in resurrection plants. United States Department of Agriculture, February 2014. http://dx.doi.org/10.32747/2014.7699861.bard.
Анотація:
In this project, we studied the photosynthetic apparatus during dehydration and rehydration of the homoiochlorophyllous resurrection plant Craterostigmapumilum (retains most of the photosynthetic components during desiccation). Resurrection plants have the remarkable capability to withstand desiccation, being able to revive after prolonged severe water deficit in a few days upon rehydration. Homoiochlorophyllous resurrection plants are very efficient in protecting the photosynthetic machinery against damage by reactive oxygen production under drought. The main purpose of this BARD project was to unravel these largely unknown protection strategies for C. pumilum. In detail, the specific objectives were: (1) To determine the distribution and local organization of photosynthetic protein complexes and formation of inverted hexagonal phases within the thylakoid membranes at different dehydration/rehydration states. (2) To determine the 3D structure and characterize the geometry, topology, and mechanics of the thylakoid network at the different states. (3) Generation of molecular models for thylakoids at the different states and study the implications for diffusion within the thylakoid lumen. (4) Characterization of inter-system electron transport, quantum efficiencies, photosystem antenna sizes and distribution, NPQ, and photoinhibition at different hydration states. (5) Measuring the partition of photosynthetic reducing equivalents between the Calvin cycle, photorespiration, and the water-water cycle. At the beginning of the project, we decided to use C. pumilum instead of C. wilmsii because the former species was available from our collaborator Dr. Farrant. In addition to the original two dehydration states (40 relative water content=RWC and 5% RWC), we characterized a third state (15-20%) because some interesting changes occurs at this RWC. Furthermore, it was not possible to detect D1 protein levels by Western blot analysis because antibodies against other higher plants failed to detect D1 in C. pumilum. We developed growth conditions that allow reproducible generation of different dehydration and rehydration states for C. pumilum. Furthermore, advanced spectroscopy and microscopy for C. pumilum were established to obtain a detailed picture of structural and functional changes of the photosynthetic apparatus in different hydrated states. Main findings of our study are: 1. Anthocyan accumulation during desiccation alleviates the light pressure within the leaves (Fig. 1). 2. During desiccation, stomatal closure leads to drastic reductions in CO2 fixation and photorespiration. We could not identify alternative electron sinks as a solution to reduce ROS production. 3. On the supramolecular level, semicrystalline protein arrays were identified in thylakoid membranes in the desiccated state (see Fig. 3). On the electron transport level, a specific series of shut downs occur (summarized in Fig. 2). The main events include: Early shutdown of the ATPase activity, cessation of electron transport between cyt. bf complex and PSI (can reduce ROS formation at PSI); at higher dehydration levels uncoupling of LHCII from PSII and cessation of electron flow from PSII accompanied by crystal formation. The later could severe as a swift PSII reservoir during rehydration. The specific order of events in the course of dehydration and rehydration discovered in this project is indicative for regulated structural transitions specifically realized in resurrection plants. This detailed knowledge can serve as an interesting starting point for rationale genetic engineering of drought-tolerant crops.