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Academic literature on the topic 'Hydraulic conductance'

Author: Grafiati

Published: 4 June 2021

Last updated: 21 February 2023

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Journal articles on the topic "Hydraulic conductance"

Toca, Andrei, Pedro Villar-Salvador, Juan A. Oliet, and Douglass F. Jacobs. "Normalization criteria determine the interpretation of nitrogen effects on the root hydraulics of pine seedlings." Tree Physiology 40, no. 10 (June 1, 2020): 1381–91. http://dx.doi.org/10.1093/treephys/tpaa068.

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Abstract Plant hydraulics is key for plant survival and growth because it is linked to gas exchange and drought resistance. Although the environment influences plant hydraulics, there is no clear consensus on the effect of nitrogen (N) supply, which may be, in part, due to different hydraulic conductance normalization criteria and studied species. The objective of this study was to compare the variation of root hydraulic properties using several normalization criteria in four pine species in response to three contrasting N fertilization regimes. We studied four closely related, yet ecologically distinct species: Pinus nigra J.F. Arnold, Pinus pinaster Ait., Pinus pinea L. and Pinus halepensis Mill. Root hydraulic conductance (Kh) was measured with a high-pressure flow meter, and values were normalized by total leaf area (leaf specific conductance, Kl), xylem cross-section area (xylem specific conductance, Ks), total root area (root specific conductance, Kr) and the area of fine roots (fine root specific conductance, Kfr). Controlling for organ size differences allowed comparison of the hydraulic efficiency of roots to supply or absorb water among fertilization treatments and species. The effect of N on the root hydraulic efficiency depended on the normalization criteria. Increasing N availability reduced Kl and Ks, but increased Kh, Kr and especially Kfr. The positive effect of N on Kr and Kfr was positively related to seedling relative growth rate and was also consistent with published results at the interspecific level, whereby plant hydraulics is positively linked to photosynthesis and transpiration rate and fast growth. In contrast, normalization by leaf area and xylem cross-sectional area (Kl and Ks) reflected opposite responses to Kr and Kfr. This indicates that the normalization criteria determine the interpretation of the effect of N on plant hydraulics, which can limit species and treatment comparisons.

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Hacke, U. G. "Variable plant hydraulic conductance." Tree Physiology 34, no. 2 (February 1, 2014): 105–8. http://dx.doi.org/10.1093/treephys/tpu007.

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Calkin, Howard W., Arthur C. Gibson, and Park S. Nobel. "Xylem water potentials and hydraulic conductances in eight species of ferns." Canadian Journal of Botany 63, no. 3 (March 1, 1985): 632–37. http://dx.doi.org/10.1139/b85-079.

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Water potentials, flow rates, and anatomy of xylary elements were studied in eight species of ferns to assess the physical constraints that xylem structure presents to water flow. Comparisons were made among ferns of different leaf morphology as well as between a fern with vessels and ferns with tracheids only. Hydraulic conductance was measured by forcing a solution through excised plant segments. These hydraulic conductances were in close agreement with conductances calculated from water potential gradients and flows measured in intact plants. In three species, backflushing excised segments by forcing a basipetal flow increased subsequently measured conductances two- to six-fold, indicating that the xylem of these three species was partially blocked in intact plants. Hagen–Poiseuille estimates of conductance based on xylary element diameters were 1.8–2.7 times the conductances measured for excised segments. Hydraulic conductances of tracheids and vessels of ferns thus deviate from those of ideal capillaries of similar diameter to about the same extent as has been reported for tracheids in conifers and for vessels in dicotyledons.

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Nguyen, Thuy Huu, Matthias Langensiepen, Jan Vanderborght, Hubert Hüging, Cho Miltin Mboh, and Frank Ewert. "Comparison of root water uptake models in simulating CO2 and H2O fluxes and growth of wheat." Hydrology and Earth System Sciences 24, no. 10 (October 23, 2020): 4943–69. http://dx.doi.org/10.5194/hess-24-4943-2020.

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Abstract. Stomatal regulation and whole plant hydraulic signaling affect water fluxes and stress in plants. Land surface models and crop models use a coupled photosynthesis–stomatal conductance modeling approach. Those models estimate the effect of soil water stress on stomatal conductance directly from soil water content or soil hydraulic potential without explicit representation of hydraulic signals between the soil and stomata. In order to explicitly represent stomatal regulation by soil water status as a function of the hydraulic signal and its relation to the whole plant hydraulic conductance, we coupled the crop model LINTULCC2 and the root growth model SLIMROOT with Couvreur's root water uptake model (RWU) and the HILLFLOW soil water balance model. Since plant hydraulic conductance depends on the plant development, this model coupling represents a two-way coupling between growth and plant hydraulics. To evaluate the advantage of considering plant hydraulic conductance and hydraulic signaling, we compared the performance of this newly coupled model with another commonly used approach that relates root water uptake and plant stress directly to the root zone water hydraulic potential (HILLFLOW with Feddes' RWU model). Simulations were compared with gas flux measurements and crop growth data from a wheat crop grown under three water supply regimes (sheltered, rainfed, and irrigated) and two soil types (stony and silty) in western Germany in 2016. The two models showed a relatively similar performance in the simulation of dry matter, leaf area index (LAI), root growth, RWU, gross assimilation rate, and soil water content. The Feddes model predicts more stress and less growth in the silty soil than in the stony soil, which is opposite to the observed growth. The Couvreur model better represents the difference in growth between the two soils and the different treatments. The newly coupled model (HILLFLOW–Couvreur's RWU–SLIMROOT–LINTULCC2) was also able to simulate the dynamics and magnitude of whole plant hydraulic conductance over the growing season. This demonstrates the importance of two-way feedbacks between growth and root water uptake for predicting the crop response to different soil water conditions in different soils. Our results suggest that a better representation of the effects of soil characteristics on root growth is needed for reliable estimations of root hydraulic conductance and gas fluxes, particularly in heterogeneous fields. The newly coupled soil–plant model marks a promising approach but requires further testing for other scenarios regarding crops, soil, and climate.

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Rejšek, K., P. Holčíková, V. Kuráž, A. Kučera, P. Dundek, P. Formánek, and V. Vranová. "Saturated hydraulic conductance of forest soils affected by track harvesters." Journal of Forest Science 57, No. 8 (August 12, 2011): 321–39. http://dx.doi.org/10.17221/6/2011-jfs.

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The exact data from the field of soil mechanics from specific forest stands exposed to forestry mechanization operation were obtained. Field surveys were performed on four study plots within the Křtiny Training Forest Enterprise, Masaryk Forest, followed by laboratory analyses of the collected soil samples aimed at evaluation of the impacts of Zetor 7245 Horal System, PONSSE ERGO 16 harvester and Gremo 950 forwarder on the compaction of upper soil horizons as well as on the dynamics of soil saturated hydraulic conductivity. A specific objective of the performed investigation was to assess the influence of the used hauling/skidding technology on measurable parameters of soil mechanics with the emphasis on a possibility to apply the Guelph permeameter for direct study of soil saturated hydraulic conductivity. In the measurement points affected by machinery operation, the impact of the changed soil structure on the values of saturated conductivity is very well noticeable – on study plots No. 3 and 4, the values decreased by one order of magnitude from 0.7 × 10–5 m·s–1 to 0.09 × 10–5 m·s–1: specifically, (i) on study plot No. 3 and from 6.9 × 10–5 m·s–1 to 0.7 × 10–5 m·s–1, and (ii) on study plot No. 4; on study plot No. 2 even by two orders, i.e. from 1.6 × 10–5 m·s–1 up to 0.03 × 10–5 m·s–1. After the operation of a universal wheeled tractor at the Babice nad Svitavou locality, the situation partially improved by one order to 0.3 × 10–5 m·s–1, similarly like at the Rudice locality to 1.5 × 10–5 m·s–1. Significant changes were found in both surface and subsurface horizons. Field-saturated hydraulic conductivity indicates also a reduction of the pore volume after machinery traffic; however, tendencies towards restoration of the original state were detectable as soon as after six months.

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Markhart, Albert H., and Barbara Smit. "Measurement of Root Hydraulic Conductance." HortScience 25, no. 3 (March 1990): 282–87. http://dx.doi.org/10.21273/hortsci.25.3.282.

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Judd, Lesley A., Brian E. Jackson, William C. Fonteno, and Jean-Christophe Domec. "Measuring Root Hydraulic Parameters of Container-grown Herbaceous and Woody Plants Using the Hydraulic Conductance Flow Meter." HortScience 51, no. 2 (February 2016): 192–96. http://dx.doi.org/10.21273/hortsci.51.2.192.

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Root hydraulic conductance and conductivity are physiological traits describing the ease with which water can move through the belowground vascular system of a plant, and are used as indicators of plant performance and adaptability to a given environment. The ability to measure hydraulic conductance of container-grown herbaceous and semiwoody plants with soft conductive tissue was tested using a hydraulic conductance flow meter (HCFM). Although the HCFM is a hydraulic apparatus that has been used on woody plants to measure hydraulic conductance of intact roots, it has never been reportedly used on container-grown horticultural plants. Two herbaceous species, Chrysanthemum L. and Solenstemon scutellarioides Thonn., were grown in containers and hydraulic parameters were measured, including root conductance and root conductivity, as well as physical traits such as stem diameter and dry root mass. The HCFM was easily connected to intact roots even on herbaceous stems and was used to determine hydraulic conductance and conductivity directly on container-grown plants with minimal disturbance on the root system. Chrysanthemums, Buddleja davidii Franch., and Hibiscus moscheutos L. were grown in three different substrates, and both root mass and root hydraulic parameters were determined. Chrysanthemums showed a positive response with increasing root hydraulic conductance with increasing root mass. The substrates used in these studies only had an effect on root biomass of chrysanthemums, but substrates had no differential effect on root hydraulic conductivity.

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Choudhary, Sunita, and Thomas R. Sinclair. "Hydraulic conductance differences among sorghum genotypes to explain variation in restricted transpiration rates." Functional Plant Biology 41, no. 3 (2014): 270. http://dx.doi.org/10.1071/fp13246.

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Sorghum (Sorghum bicolor L.) is an important crop for production in dryland regions of the globe. Traits identified in many sorghum lines that apparently make them adapted for dryland conditions are restricted transpiration rate both early in the soil drying cycle and under high atmospheric vapour pressure deficit. It was hypothesised that these responses could be a result of differences in hydraulic conductance of the plants: those with low hydraulic conductance would be more likely to express restricted transpiration rates. The location of the lower hydraulic conductance in the plant could also be important with a low conductance in the leaf xylem to stomata pathway possibly being more advantageous than in the root. In this study, the amount and location of the hydraulic conductance was measured in 20 sorghum genotypes. Those genotypes that expressed an early decrease in transpiration rate with soil drying had greater plant and leaf hydraulic conductance than those genotypes that had the later decreases in transpiration rate, which was in contrast with what was hypothesised. However, sorghum genotypes that segregated between two groups based on expression of a maximum transpiration trait also segregated based on their hydraulic conductance. Those genotypes that expressed the maximum transpiration trait had lower hydraulic conductance for the intact plant and in the leaves.

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Schulte, Paul J., and Arthur C. Gibson. "Hydraulic conductance and tracheid anatomy in six species of extant seed plants." Canadian Journal of Botany 66, no. 6 (June 1, 1988): 1073–79. http://dx.doi.org/10.1139/b88-153.

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Hydraulic conductance of tracheids was studied in either petioles or young stems of six species of seed plants having various types of intertracheid pitting. Measured conductances were compared with estimates based on Hagen–Poiseuille flow through ideal capillaries and with predictions from a biophysical model incorporating observed anatomical characteristics of tracheids and intertracheid pits. Conductance of the xylem, expressed as a percentage of the ideal capillary flow prediction, varied from an average of 88% for a species containing only very narrow tracheids to less than 35% for species with large-diameter tracheids. The biophysical model allowed fairly close predictions of conductance for all species except one, where an estimate of the pit membrane resistance could not be experimentally obtained. For individual tracheids, conductance was largely a function of lumen diameter, pit membrane resistivity, and the exposed area of the pit membranes, as determined by pit shape, size, and frequency. For wide tracheids, scalariform-pitted elements showed a linear increase in conductance with an increase in lumen diameter; however, for tracheids with large circular pits, the conductance increase afforded by a wider lumen declines as lumen diameter increases. These model simulations demonstrate the increasing significance of intertracheid pitting in obstructing flow as lumen diameter increases.

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Meinzer, FC, DA Grantz, and B. Smit. "Root Signals Mediate Coordination of Stomatal and Hydraulic Conductance in Growing Sugarcane." Functional Plant Biology 18, no. 4 (1991): 329. http://dx.doi.org/10.1071/pp9910329.

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Root hydraulic conductance and total stomatal conductance on a per plant basis changed in parallel during growth of sugarcane. Changes in root system water and solute transport properties were evaluated to determine the role of changes in root xylem sap composition in this coordination of vapour and liquid phase conductances. Stomatal conductance of excised leaf strips supplied with root exudate declined with increasing leaf area of the exudate donor plants. Leaf strips from plants of different sizes responded similarly to exudate from each donor plant, indicating that there were no inherent differences in leaf stomatal properties. The effect of xylem sap from plants of increasing size paralleled the decline in stomatal conductance of intact plants of similarly increasing plant size. Delivery rates per unit leaf area of K+, Ca2+, abscisic acid, and zeatin riboside (ZR) in xylem sap declined with increasing plant size. Patterns of delivery of ZR and K+ were consistent with a role in the plant size-dependent regulation of stomatal conductance, although additional xylem constituents are likely to be involved. Developmental patterns of stomatal conductance in intact sugarcane plants may be linked to plant hydraulic properties by the composition and flux of xylem sap arriving at the stomatal complexes in leaves.

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Dissertations / Theses on the topic "Hydraulic conductance"

Agyei, Festus O. "TEMPORAL AND SPATIAL VARIABILITY OF RIVERBED CONDUCTANCE AT THE BOLTON WELLFIELD ALONG THE GREAT MIAMI RIVER, SOUTHWEST OHIO." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1166069378.

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Lamkey, Nick C. "DELINEATING CAPTURE ZONES USING A SYSTEMATIC SENSITIVITY ANALYSIS THAT VARIES RECHARGE, HYDRAULIC CONDUCTIVITY AND CONDUCTANCE." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2386.

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The Saline Valley Conservancy District (SVCD) formed in 1980 to provide groundwater to communities in Saline and Gallatin, Counties, Illinois. Sulfate contamination from a nearby coal mine threatens the SVCD’s current well field. Three of the wells are reaching the end of their service and have elevated levels of sulfate. This study investigated multiple well configurations on three different parcels of land to find possible new well locations that do not recharge water directly from the mine site over a 50-year period. A steady-state finite difference groundwater flow model was created using Graphic Groundwater GIS (Krienert and Esling, 2016), a pre and post-processor for MODFLOW (Harbaugh, 2005) and MODPATH (Pollock, 2012). The calibration and sensitivity analysis followed methods from Esling et al. (2008). Hydraulic heads were calibrated to the land surface and a systematic sensitivity analysis varied recharge, hydraulic conductivity, and drain and river conductance to produce composite capture zones. Well locations must also meet SVCD requirements that would minimize distance from current water lines and consider properties they already owned. New wells also needed to be located in areas where the aquifer exceeds 25 m thick and be separated by 305 meters to minimize drawdown. This study also considered the effects of irrigation on the aquifer. Varying recharge, hydraulic conductivity and conductance within reasonable ranges created six capture zones for the proposed wells, each with different geometries. The capture zones were superimposed onto a map to make a composite capture zone which should contain the actual capture zone for the wells. Varying conductance caused subtle changes in capture zone geometry. Low values of conductance caused particle tracks to elongate. Irrigation wells and some proposed well locations caused substantial dewatering in one area of the aquifer. The study discovered several well configurations on each of the parcels that do not source water from the mine site over 50 years.

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Rzigui, Touhami. "Analyse de la réponse d’un mutant mitochondrial de Nicotiana sylvestris au manque d’eau." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112144/document.

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Pour étudier le rôle de la mitochondrie dans la tolérance à la sécheresse, la réponse à la contrainte hydrique a été comparée entre une lignée sauvage (WT) et un mutant CMSII (Cytoplasmic Male Sterile) de Nicotiana sylvestris. Chez le mutant CMSII, le complexe I mitochondrial est absent et la respiration est assurée par les NAD(P)H déshydrogénases alternes et elle est maintenue à un niveau supérieur de l’ordre de 20 à 30% à celui du WT. La différence observée entre les plantes WT et CMSII met en jeu non seulement le fonctionnement mitochondrial, mais également le fonctionnement des chloroplastes. En effet, l’activité photosynthétique du mutant est plus faible que celui du WT et elle est corrélée avec une plus faible conductance stomatique (gs) et mésophyllienne (gm).Après l’arrêt de l’arrosage, on observe que le contenu relatif en eau (RWC) diminue plus lentement chez les feuilles du CMSII. Ceci n’était pas le résultat d’une plus petite surface de transpiration ou d’une masse racinaire d’absorption plus élevé puisque le rapport partie aérienne/racine et la surface foliaire totale ont été similaires au début de l’expérience chez les deux génotypes. De plus la mutation n’a pas induit des changements au niveau des paramètres hydriques (P0, PTLP, RWCTLP) ni au niveau de la densité stomatique. La tolérance des plantes CMSII a été le plus probablement la conséquence de sa plus faible transpiration en conditions bien hydratées et aux premiers jours de déshydratation et non pas d’une meilleure efficacité d’absorption de l’eau puisque le contenu en eau du sol reste plus élevé chez CMSII après l’arrêt de l’arrosage. La plus faible conductance stomatique chez le CMSII bien hydraté a été expliquée par sa plus faible conductance hydraulique. De plus, contrairement au WT, le niveau des acides aminés totaux diminue au cours de la déshydratation lorsque le contenu en protéines solubles augmente chez les feuilles du CMSII, suggérant une accélération de la remobilisation des acides aminés. D’autre part, il a été aussi montré que le mutant CMSII est capable de s’acclimater mieux à la sécheresse que le WT lorsqu’ils ont été maintenus à un RWC de 80 % sur plusieurs jours. Sous ces conditions, la photosynthèse reste plus élevée chez le mutant que chez le WT. Cette meilleure acclimatation corrèle avec une plus forte photorespiration du CMSII sous conditions bien hydratées et sous conditions d’acclimatation. La photorespiration chez CMSII et le WT a été estimée par le transport électronique dévolu à l’oxygénation de RuBP et en plus par l’accumulation des métabolites impliqués dans la photorespiration. D’une part, l’acclimatation à la sécheresse diminue gm plus fortement chez le WT que chez le CMSII. D’autre part, le WT accumule la glycine ce qui laisse supposer que le glycine décarboxylase mitochondrial est plus affectée chez le WT que chez le CMS et inhibe ainsi la photorespiration. En effet, cette plus faible photorespiration chez le WT affecte les réactions primaires de la photosynthèse par une accumulation d’un gradient de protons estimé par le quenching non-photochimique (NPQ) de la fluorescence chlorophyllienne ce qui induit une diminution du transport électronique des réactions primaires de la photosynthèse
To investigate the role of mitochondria in drought stress, the response to water deprivation was compared between Nicotiana sylvestris wild type (WT) plants and the CMSII respiratory complex I mutant. In CMSII, alternative NAD(P)H-dehydrogenases bypassing complex 1 allow respiration.. The difference of mitochondrial function between WT and CMSII plants affect also photosynthesis. The CMSII has lower photosynthetic actitvity than the WT and lower stomatal (gs) and internal (gm) conductances to CO2. When watering of plants with similar leaf surface and similar shoot/root ratio was stopped the relative water content (RWC) declined faster in WT as compared to CMSII leaves. Furthermore, CMSII and WT leaves had the same osmotic potential at leaf saturation (P0) and at leaf turgor lost pressure (PTLP) and the same stomatal density. The slower decline of RWC in CMSII, compared to WT leaves, was most likely the consequence of the lower stomatal conductance (gs) under well-watered conditions and during the first days after withholding watering, The lower stomatal conductance of well-watered CMSII leaves correlated with a lower hydraulic conductance of leaves. Remarkably, total free amino acid levels declined and total soluble protein content increased in CMSII leaves, while the opposite was observed in WT leaves. This suggests protein synthesis in CMSII but protein degradation in WT leaves during drought stress. We also show that CMSII leaves better acclimate to drought stress than the WT leaves. After several days at 80 % RWC , photosynthesis is higher in the mutant than in WT. As compared to the WT, the mutant shows higher rates of photorespiration before and after acclimation to drought.The strong accumulation of glycine in the WT suggests that photorespiration may be limited at the level of glycine decarboxylase. In addition, after acclimation to drought gm declined markedly in WT but not in CMSII leaves, thus further limiting CO2 supply for photosynthesis in the WT. The resulting lower photosynthesis and photorespiration in WT leaves affect also the primary reaction of photosynthesis by increasing the non-photochemical fluorescence quenching (NPQ) and decreasing linear electron transport

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Lorentzon, Martin. "Grundvattenmodellering i Badelundaåsen." Thesis, Uppsala University, Department of Earth Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88903.

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Over an extended period of time there have been plans to establish a shared facility in Lennheden to extract groundwater from the Badelunda esker to provide drinking water for the cities of Borlänge and Falun. The city of Falun is dissatisfied with the quality of its drinking water and the city of Borlänge is concerned about the risk of contamination of its existing groundwater supply at its current location. To provide a basis for a decision on this issue, the company Midvatten AB has been commissioned to perform hydrogeological investigations in the area of Lennheden.

The purpose of this thesis is to design a functional groundwater model of the area between Lennheden, place of planned extraction, and Övre Tjärna, place of existing extraction, to get a better understanding of the groundwater situation in the area. A groundwater model enables simulations of different scenarios in risk assessment and contaminant transport. The aim of the thesis is that the model can be used as an aid in Midvatten’s investigations in Lennheden and that it also can be used in future projects in the area.

The model has been made in Processing Modflow 5.3 and encompasses an area of 19,5 × 11 km along the Badelunda esker and the river Dalälven between Djurmo and Frostbrunnsdalen. The model has 6 layers and a cell resolution of 50 × 50 meters and 50 × 100 meters. The physical parameters of the model are comprised from different hydrological and geological investigations in the area.

The Badelunda esker and the river Dalälven totally dominate the groundwater situation in the area. A large part of the work in the thesis has been focused on the calibration of the horizontal hydraulic conductivity in the esker and the vertical hydraulic conductivity in the riverbed of Dalälven. The calibration of the model implies a vertical hydraulic conductivity of 0,01 – 0,1 md-1 in the riverbed of Dalälven, depending on the riverbed thickness.

Between Bäsna and Övre Tjärna, simulated and observed groundwater levels correspond well. The transport time of the water in the esker, simulated in PMPATH, also corresponds well with estimated transport times. The model can be used for simpler studies of contaminant transport.

Simulation of the pumping test in Lennheden gives a good correspondence eastward in the esker from Lennheden to Övre Tjärna. Westward in the esker, from Lennheden to Bäsna, the draw down is sharper than observed. Possible reasons for the sharper draw down is an underestimation of the bulk of the esker and that the vertical hydraulic conductivity of the riverbed is set too low between Lennheden and Bäsna.

In order to improve the model, the most important step should be to thoroughly investigate the river Dalälven with regards to vertical hydraulic conductivity in the riverbed and riverbed thickness.

Under en längre tid har det funnits planer på att upprätta en ny, gemensam vattentäkt för Borlänge och Falu kommun i Badelundaåsen i Lennheden nordväst om Borlänge stad. Falu kommun är missnöjd med vattenkvaliteten i sin ytvattentäkt och Borlänge är oroad över riskerna med att ha sin nuvarande vattentäkt i Badelundaåsen lokaliserad i nära anslutning till riksväg 70 och järnvägen. Beslut i frågan ska tas under 2006 och Midvatten AB har fått i uppdrag att genomföra geohydrologiska undersökningar i och runt Lennheden som underlag till beslutet.

Syftet med det här examensarbetet är att skapa en fungerande grundvattenmodell för området mellan Lennheden, plats för planerat vattenuttag, och Övre Tjärna, plats för befintligt vattenuttag, för att få en större förståelse för grundvattenmagasinet. En grundvattenmodell möjliggör simulering av olika scenarion så som föroreningstransport i grundvattnet och bestämning av skyddsområden. Målet är att modellen ska kunna användas som ett komplement i Midvattens undersökningar och även användas i framtida projekt i området.

Modellen är gjord i Processing Modflow 5.3 och omfattar ett 19,5 × 11 km stort område längs Badelundaåsen och Dalälven mellan Djurmo och Frostbrunnsdalen. Modellen består av 6 lager där cellernas upplösning är 50 × 50 meter och 50 × 100 meter. De fysiska parametrar som modellen är uppbyggd av är sammanställda från olika hydrologiska och geologiska undersökningar som har utförts i området de senaste 30 åren.

Badelundaåsen och Dalälven är de två komponenter som totalt dominerar grundvattensituationen i området. En stor del av arbetet har fokuserats på kalibreringen av den horisontella hydrauliska konduktiviteten i åsen och den vertikala hydrauliska konduktiviteten i Dalälvens botten. I modellen är den vertikala hydrauliska konduktiviteten i Dalälvens botten kalibrerad till intervallet 0,01 – 0,1 md-1 beroende på bottnens mäktighet.

På sträckan mellan Bäsna och Övre Tjärna så fungerar modellen bra. Simulerade och observerade grundvattennivåer stämmer väl överens. Även vattnets transporttider i åsen, simulerade i PMPATH, stämmer väl överens med uppskattade transporttider. Modellen kan användas för enklare studier av ämnestransport.

Vid simulering av provpumpningen i Lennheden så är överensstämmelsen god österut i åsen, från Lennheden till Övre Tjärna. Västerut i åsen, från Lennheden till Bäsna, är avsänkningen av grundvattennivån för kraftig. Möjliga orsaker till den för kraftiga avsänkningen är att åsens utbredning är underskattad och att Dalälvens botten har en för lågt ansatt vertikal hydraulisk konduktivitet längs sträckan Lennheden – Bäsna.

Den klart viktigaste åtgärden för att förbättra modellen skulle vara att grundligt undersöka Dalälven, särskilt längs sträckan Djurmo – Båtsta, med avseende på dess bottens vertikala hydrauliska konduktivitet och mäktighet.

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Idris, Omonigho. "Temporal variability of riverbed conductance at the Bolton Well Field along the Great Miami River, Southwest Ohio: Characterization of riverbed sediments during low-flow conditions." Oxford, Ohio : Miami University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1146764820.

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Ocheltree, Troy W. "Growth and survival during drought: the link between hydraulic architecture and drought tolerance in grasses." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13803.

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Doctor of Philosophy
Department of Agronomy
P.V. Vara Prasad
The pathway for the movement of water through plants, from the soil matrix to the atmosphere, constitutes the hydraulic architecture of a plant. The linkage between the hydraulic architecture of woody plants and drought tolerance has received considerable attention, but much less work has been done on grasses. I investigated the linkage between the hydraulic architecture of grasses to physiological patterns of water use across a range of species and conditions. The rate of stomatal conductance (g[subscript]s) and photosynthesis (A) increased acropetally along the leaves of 5 grass species, which is a unique feature of this growth form. The internal structure of leaves also changed acropetally in order to minimize the pressure gradient across the mesophyll that would otherwise occur as a result of increasing g[subscript]s. The resistance to water movement through the mesophyll represented 80-90% of leaf resistance in six genotypes of Sorghum bicolor L. (Moench). This resistance was most important in controlling g[subscript]s and A when water was readily available, but as soil-moisture decreased it was the efficient transport of water through the xylem that was most important in maintaining plant function. I also investigated the relationship between hydraulic architecture and stomatal responses of grasses to increasing Vapor Pressure Deficit (D). Grasses with a larger proportion of their hydraulic resistance within the xylem were less sensitive to increasing D and plants with high root conductance maintained higher rates of gas exchange D increased. Finally, I investigated the tolerance of grasses to extreme drought events to test if there was a trade-off between drought tolerance and growth in grasses. Plants with drought tolerant leaf traits typically sacrificed the ability to move water efficiently through their leaves. Having drought tolerant leaves did not limit the plants ability to have high rates of gas exchange, and, in fact, the most drought tolerant plants had the high rates of g[subscript]s when expressed on a mass basis. Leaf-level drought tolerance did contribute to species’ occurrence, as the drought intolerant species I studied are not commonly found in low precipitation systems. The results presented here highlight the importance of studying the hydraulic architecture of plants to provide a better understanding of what controls plant function across a range of environmental conditions.

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Reis, Karina Lima. "Desenvolvimento de um método para estimativa da condutância hidráulica e avaliação da atividade de aquaporinas em plântulas de milho." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-28082013-105742/.

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O transporte de água nas plantas é um processo complexo e que envolve a passagem por membranas celulares. Nelas existem aquaporinas, proteínas integrais de membrana, que facilitam o fluxo passivo de água e pequenos solutos. Um fator importante que influencia o transporte de água nas plantas é a condutância hidráulica radicular (LPr), que pode contribuir com até 50% de toda a resistência ao fluxo de água na planta. Várias metodologias são propostas para estimar a LPr, porém os dados obtidos são altamente variáveis, ainda que para a mesma espécie vegetal. Diante do exposto, pretende-se desenvolver e propor uma nova metodologia, o sistema hidráulico de sucção para estimativa da LPr e avaliar a contribuição das aquaporinas no transporte de água radicular em plântulas de milho. O sistema hidráulico de sucção foi construído no Laboratório de Estudos de Plantas sob Estresse (LEPSE/USP) em parceria com Laboritoire d\'Ecophysiologie des Plants sous Stress Environnementaux de Montpellier, França. Os experimentos foram conduzidos no LEPSE, onde as plântulas cresceram em hidroponia na casa de vegetação. Para avaliação da atividade de aquaporinas foi utilizado o tratamento com peróxido de hidrogênio, que em concentrações milimolares inibe os canais de água. As medidas de condutância foram realizadas sempre na mesma hora do dia, uma vez que a própria LPr e as aquaporinas apresentam ritmo circadiano. Houve redução de 53% da condutância no tratamento com peróxido em relação ao controle e correlação significativa entre a LPr e o pH, de modo que o aumento do pH provocou queda de LPr, provavelmente causada por alterações na abundância e/ou atividade de aquaporinas nas raízes de milho. Esses resultados permitem afirmar que o método de sucção foi eficaz na estimativa da condutância hidráulica, podendo ser adotado como técnica alternativa na estimativa da LPr em plantas.
The water transport in plants is a complex process which involves passage through cell membranes. In them there are aquaporins, integral membrane proteins, that facilitate passive flux of water and small solutes. An important factor influencing the water transport in plants is root hydraulic conductance (LPr), which can contribute up to 50% of the water flow resistance in the plant. Various methods are proposed for estimating LPr, but the data are highly variable, even for the same plant species. Therefore, we intend to develop and propose a new methodology, the hydraulic suction system to estimate LPr and evaluate the contribution of aquaporins in root water transport in maize seedlings. The hydraulic suction system was built at the Laboratório de Estudos de Plantas sob Estresse (LEPSE / USP) in partnership with Laboritoire d\'Ecophysiologie Plants des sous Stress Environnementaux Montpellier, France. The experiments were conducted in LEPSE where the seedlings grew in the hydroponics greenhouse. To evaluate the activity of aquaporins was used treatment with hydrogen peroxide, which in millimolar concentrations inhibits water channels. The conductance measurements were performed at the same time of day, since the LPr itself and aquaporins presents the circadian rhythm. There was a 53% reduction in conductance peroxide treatment compared to control and significant correlation between LPr and pH, so that the pH increase caused a drop LPr probably caused by alterations in the abundance and/or activity of aquaporins in maize roots. These results indicate that the suction method was efficient in estimated hydraulic conductance, may be adopted as an alternative technique to estimate the LPr in plants.

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Rossdeutsch, Landry. "Contribution du métabolisme de l'ABA et de la conductivité hydraulique à la réponse de la transpiration en situation de contrainte hydrique chez la Vigne : Variabilité génétique et effets du greffage." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0256/document.

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Dans le contexte de changement climatique, la compréhension des mécanismes régissant les pertes en eau de la vigne peut permettre d'adapter le matériel végétal pour maintenir la productivité de la vigne et la qualité du vin. L'adaptation à la sécheresse est un caractère complexe faisant intervenir des mécanismes physiologiques liés aux génotypes du greffon et du porte-greffe. Mais les effets du porte-greffe sur la régulation stomatique du greffon sont mal connus. La production par les racines de signaux chimiques tels que l'ABA et/ou hydraulique pourraient y contribuer. La réponse physiologique et moléculaire à la contrainte hydrique a été analysée sur de jeunes boutures pour 7 porte-greffes plus ou moins adaptés à la sécheresse et 2 cépages connus pour leur caractère iso ou anisohydrique. Puis 23 combinaisons greffon/porte-greffe issues de ces génotypes ont été étudiées. Une analyse métabolique sur l'accumulation de l'ABA et ses dérivés a été menée sur feuilles, racines et dans la sève xylémienne. Ces informations ont été couplées à des analyses transcriptomiques sur des gènes du métabolisme et de la signalisation de ABA, et codant des aquaporines de type PIP. L‘analyse conjointe des données physiologiques, métabolomiques et transcriptomiques ont permis d'identifier des composants moléculaires discriminant les porte-greffes selon leur fond génétique et leur adaptation à la sécheresse. Les réponses globales à la contrainte hydrique sont mieux coordonnées au sein d‘un même tissu qu‘entre racines et feuilles. A l‘échelle de la plante greffée, une prépondérance du signal hydraulique est probable. Certains gènes répondent spécifiquement aux interactions greffon/porte-greffe
In the context of climate change, understanding the mechanisms governing the water loss of the vine is necessary to adapt the plant material to maintain the productivity of the vine and wine quality. The adaptation to drought is a complex trait involving physiological mechanisms related to scion and rootstock genotypes. But the effects of the rootstock on stomatal regulation graft are still unknown. Production by roots of chemical signals such as ABA and / or hydraulic ones be involved. Molecular and physiological responses to water stress were analyzed on young cuttings for 7 rootstocks more or less adapted to drought and 2 varieties known for their iso or anisohydric behaviour. Then 23 combinations scion / rootstock from these genotypes were investigated. Metabolic analyses for ABA and its derivatives was conducted in leaves, roots and in the xylem sap. The information was integrated with transcriptomic analyzes for genes involved in ABA metabolism and signaling, and encoding PIP aquaporins. Joint analyses of physiological data, metabolomic and transcriptomic allow the identification of the molecular components discriminating rootstocks according to their genetic background and their adaptation to drought. Global responses to water stress are better coordinated within the same tissue between roots and leaves. At the scale of the grafted plant, a preponderance of the hydraulic signal is likely. Some genes specifically respond to the scion / rootstock interactions

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Oliveira, Tatiane Alexandre de. "Avaliação da estabilidade da aplicação de um híbrido experimental em diferentes concentrações sobre a dentina sensível - in vitro." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/23/23134/tde-04032017-121932/.

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O objetivo deste estudo foi avaliar, in vitro, quantitativamente e qualitativamente, a estabilidade de um híbrido experimental em duas concentrações diferentes (concentrado e diluído) aplicado sobre a simulação de uma dentina sensível. Dentes molares humanos foram selecionados e tiveram suas coroas seccionadas abaixo do sulco oclusal de forma a obter espécimes de discos de dentina que foram planificados e polidos até atingirem a espessura de 1,0 milímetro. Os espécimes foram divididos em 4 grupos (n=9) de acordo com os tratamentos de superfície propostos: saliva artificial (SAL), adesivo dentinário autocondicionante (AD), híbrido experimental concentrado (TC) e híbrido experimental diluído na proporção de 1:3 (TD). Dois métodos foram empregados para avaliar a estabilidade: condutância hidráulica (permeabilidade dentinária) e microscopia eletrônica de varredura. Foi realizada a leitura da permeabilidade dentinária em 6 tempos experimentais: Mínima (sem tratamento), Máxima (com túbulos abertos), Tratamento (após aplicação dos respectivos tratamentos), Erosão (após 5 minutos de imersão em ácido cítrico 0,05M pH 3,8), Escovação (após escovação de 3900 ciclos) e Erosão Pós (repetição da erosão após o processo de escovação). A microscopia eletrônica de varredura foi realizada em espécimes de dentina com área central de aplicação dos tratamentos e tecido natural nas laterais para evidenciar as características da película aplicada. As leituras foram feitas após a aplicação dos tratamentos, após a erosão, após a escovação e após a erosão pós escovação, para todos os 4 tratamentos propostos. O teste de análise de variância (ANOVA) de Medidas Repetidas com 2 fatores de variação foi aplicado juntamente com o teste de comparações múltiplas pareadas (Tukey). Para permeabilidade dentinária todos os tratamentos reduziram a condutância hidráulica (Lp) em relação à Máxima. TC e TD apresentaram os menores valores (24% e 15%) respectivamente. O TD continuou apresentando valores semelhantes estatisticamente após a Erosão (36%), sendo estatisticamente semelhante ao TC (55%).. No tempo Escovação o TD apresentou Lp estatisticamente semelhante aos tempos Tratamento e Erosão. Todos os grupos apresentaram-se estatisticamente semelhantes entre os tratamentos nos tempos Escovação e Erosão Pós. A análise das MEVs evidencia túbulos dentinários com conteúdo no seu interior nos grupos TC e TD, mantendo-se durante todos os tempos experimentais. O AD apresentou uma película evidente, que começou a se destacar e exibir falhas a partir do tempo Erosão. Conclui-se que o TD apresentou o melhor comportamento sendo capaz de diminuir a permeabilidade dentinária, formando uma película fina, transparente, imperceptível, capaz de vedar (totalmente ou parcialmente) e penetrar dentro dos túbulos dentinários, resistindo aos desafios erosivos e abrasivos.
The aim of this study was to evaluate, in vitro, quantitatively and qualitatively, the stability of an experimental hybrid with two different concentrations (concentrated and diluted) applied at a simulation of a sensitive dentin. Human molar teeth were selected and their crowns were sectioned below the occlusal groove in order to obtain specimens of dentine disks that were ground flat and polished to achieve a thickness of 1.0 millimeter. The specimens were divided into 4 groups (n = 9) in accordance with proposed surface treatments: Artificial saliva (SAL) dentinal self-etching adhesive (AD), concentrated experimental hybrid (TC) and experimental hybrid diluted in the ratio 1: 3 (TD). Two methods were used to assess the stability: hydraulic conductance (dentin permeability) and scanning electron microscopy. The dentin permeability in 6 experimental times was carried out: Minimum (no treatment), Maximum (with open tubules), treatment (after application of their treatments), erosion (after 5 minutes of immersion in citric acid 0.05M pH 3, 8), brushing (brushing after 3900 cycles) and Post erosion (erosion was repeated after brushing). The scanning electron microscopy was performed on dentin specimens with a central area of application of treatments and natural tissues on the sides to show the film characteristics applied. Readings were made after application of treatments, after erosion, after brushing and after erosion after brushing, for all 4 treatments proposed. The analysis of variance (ANOVA) for repeated measures with two variation factors was applied with the multiple comparisons paired test (Tukey). For dentin all treatments reduced hydraulic conductance (Lp) in relation to Maximum. TC and TD showed the lowest values (24% and 15%) respectively. The TD continued to show statistically similar values after erosion (36%), being statistically similar to TC (55%). In brushing time the TD Lp was statistically similar to Treatment and erosion times. All groups were statistically similar between treatments in brushing and Post Erosion times. The analysis of SEM shows dentinal tubules with content inside on the TC and TD groups, remaining during all experimental period. AD presented a clear film, which began to stand out and show failure from erosion time. It follows that the TD had better behavior being able to decrease permeability of dentin by forming a thin film transparent, imperceptible, capable of sealing (fully or partially) and penetrate within the dentine tubules, resisting the erosive and abrasive challenges.

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Inman, William W. "Hydraulic resistance a determinant of short term stomatal conductance signaling in disparate xylem anatomy of Red Maple (Acer rubrum L.) and Shumard Oak (Quercus shumardii Buckl.) /." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1181251213/.

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Books on the topic "Hydraulic conductance"

Kort, John. Hydraulic and canopy conductances in hybrid poplar clones. 2005.

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Book chapters on the topic "Hydraulic conductance"

Lovisolo, Claudio, and Sara Tramontini. "Methods for Assessment of Hydraulic Conductance and Embolism Extent in Grapevine Organs." In Methodologies and Results in Grapevine Research, 71–85. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9283-0_6.

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Tardieu, F. "Control of Stomatal Conductance in Droughted Plants by Hydraulic and Chemical Messages from Roots." In Photosynthesis: from Light to Biosphere, 4423–28. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-009-0173-5_1039.

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Ruffault, Julien, Jean-Marc Limousin, François Pimont, Jean-Luc Dupuy, Hervé Cochard, and Nicolas Martin-StPaul. "SurEau-Ecos-FMC: mechanistic modelling of fuel moisture content (FMC) at leaf and canopy scale under extreme drought." In Advances in Forest Fire Research 2022, 1318–22. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_199.

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Understanding and predicting fuel moisture content (FMC) is a crucial prerequisite to increase our knowledge of forestâ€™s vulnerability to fires in a changing climate. While live fuel moisture content (LFMC) is a main driver of fire behavior and activity in crown fires in forests and shrublands, it remains poorly understood and predicted, especially under extreme drought. A major reason for that is that LFMC sensitivity to climate is mediated by a range of location-specific factors, including soil characteristics and plant response to drought. Another reason is that LFMC is often simulated at the leaf scale while, from a fire danger perspective, canopy scale fuel moisture content (CFMC) is more relevant. Here we introduced a FMC module in the plant-hydraulic SurEau-Ecos model to simulate the dynamics of both LFMC and CFMC as a function of leaf water potential (psi_{Leaf}). CFMC integrates the impacts on moisture content of foliage mortality that can occur under extreme drought because of leaf embolism. SurEau-Ecos-FMC relies on two main mechanisms. The relationship between psi_{Leaf} and leaf relative water content of the symplasm is modeled through pressure volume curves. Percent loss of leaf conductance (PLC) is derived from psi_{Leaf} through vulnerability curves to cavitation and affects the dynamics of fuel moisture content in two different ways. At the leaf level, PLC dictates the dynamics of the leaf apoplasmic reservoir. At the canopy level, PLC drives the proportion of dead fuel within the canopy. SurEau-Ecos-FMC captured relatively well the temporal dynamics of LFMC measured in a Quercus ilex stand at the PuÃ©chabon site over a three-years period. The model explained 69 % (RMSE = 4.27) and 74 % (RMSE = 4.92) of the variance in the minimum and maximum daily observed LFMC, respectively. The model was also able to capture the dynamics in CFMC resulting from leaf mortality during the summer drought. Indeed, we showed that the years when SurEau-Ecos-FMC predicted leaf mortality were the ones with the highest anomaly in NDVI. Multi-model projections of fire danger indices based on CFMC showed a general increase of fire danger over the next century. Under RCP8.5, the averaged minimum CFMC reached during the year is expected to decrease from 65 % to 32 % and the fire season length (number of day when CFMC

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Conference papers on the topic "Hydraulic conductance"

Holahan, Maurice F. "Mapping Potential Heatsink Conductance Across the Hydraulic Plane." In ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems collocated with the ASME 2005 Heat Transfer Summer Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ipack2005-73423.

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A systematic examination of parallel plate fin heat sink performance is carried out by means of a parametric study focussed on aluminum and copper fins in air. The objective is to find the maximum available fin conductance of fixed fin volumes as a function of hydraulic operating point. The fin pitch, height, flow length, and thickness/gap solidity are all varied. Peak volumetric conductance fin geometries are established using a search algorithm. The results are presented as a continuous mapping of peak-enabling fin geometry across the flow-pressure hydraulic operating plane. A correlation is presented showing how the peak conductance varies with pressure, fin volume, and material conductivity.

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Opdenbosch, Patrick, Nader Sadegh, and Wayne J. Book. "Modeling and Control of an Electro-Hydraulic Poppet Valve." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59751.

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This paper explores the dynamic modeling of a novel two stage bidirectional poppet valve and proposes a control scheme that uses a Nodal Link Perceptron Network (NLPN). The dynamic nonlinear mathematical model of this Electro-Hydraulic Control Valve (EHCV) is based on the analysis of the interactions among its mechanical, hydraulic, and electromagnetic subsystems. A discussion on experimental approaches to determine the model parameters is included along with model validation results. Finally, the control scheme is developed by proposing that the states of the EHCV follow a set of desired states, which are calculated based upon the desired valve flow conductance coefficient KV. A simulation is presented at the end to verify the proposed control scheme.

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Alcolea Rodriguez, A., and U. Kuhlmann. "Hydraulic Conductance of the EDZ around Underground Structures of a Geological Repository for Radioactive Waste." In Fourth EAGE Shale Workshop. Netherlands: EAGE Publications BV, 2014. http://dx.doi.org/10.3997/2214-4609.20140043.

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Opdenbosch, Patrick, and Nader Sadegh. "Control of Electro-Hydraulic Poppet Valves via Online Learning and Estimation." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80980.

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Online learning state trajectory control applied to Electro-Hydraulic Poppet Valves (EHPV) is considered herein. The control problem is to track a desired flow conductance coefficient KV for pressure or flow control applications. In general terms, the control methodology employed herein computes the input signal sent to the valve from the addition of three components. The first component comes from an experimentally approximated inverse input-output map of the system which gives a nominal input. The second component is computed through a neural network structure called the Nodal Link Perceptron Network that learns online the adjustment of this nominal map. The third component is an adaptive proportional feedback control input. This last component uses two system parameters known as the Jacobian and the Controllability parameter, which are estimated online via a recursive least squares algorithm with forgetting factor. The proposed controller is explored through experimental data on a pressure control application and the results are discussed.

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Kumar, Avinash, Subhra Datta, and Dinesh Kalyanasundaram. "Reduction of Hydraulic Friction in Confined Flows by Laser Texturing: Experiments and Theoretical Validation." In ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icnmm2018-7740.

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Hydraulic friction reduction in a microchannel due to superhydrophobic texturing of its walls was studied theoretically and experimentally. A modified Poiseuille equation formulated from an earlier-established semi-analytical approach to model texturing of slip lengths and the “gas cushion model” was used to predict the hydraulic conductance of a microchannel. An experimental setup with a microfluidic flow cell consisting of syringe pump, pressure manometer and tubing measured the pressure drop at different flow rates through a microchannel. The top and bottom walls of the microchannel was textured with micro-pits using nanosecond pulsed laser on the titanium alloy Ti6Al4V. A very high contact angle was observed on the textured surfaces suggesting entrapped gas bubbles. Liquid slippage leading to reduced hydraulic friction is attributable to the bubbles. The pressure-flow rate characteristics of the microchannels confirm friction reduction and also demonstrate a reasonable agreement with the theoretical predictions from the developed fluid dynamic model.

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Emerson, David R., and Robert W. Barber. "Designing Efficient Microvascular Networks Using Conventional Microfabrication Techniques." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18312.

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The ability to fabricate networks of micro-channels that obey the biological properties of bifurcating structures found in nature suggests that it is possible to construct artificial vasculatures or bronchial structures. These devices could aid in the desirable objective of eliminating many forms of animal testing. In addition, the ability to precisely control hydraulic conductance could allow designers to create specific concentration gradients that would allow biologists to correlate the behavior of cells. In 1926, Murray found that there was an optimum branching ratio between the diameters of the parent and daughter vessels at a bifurcation. For biological vascular systems, this is referred to as Murray’s law and its basic principle has been found to be valid in many plant and mammalian organisms. An important consequence arises from this law: when the successive generations consist of regular dichotomies, the tangential shear stress at the wall remains constant throughout the network. This simple concept forms an elegant biomimetic design rule that will allow designers to create complex sections with the desired hydraulic conductance or resistance. The paper presents a theoretical analysis of how biomimetic networks of constant-depth rectangular channels can be fabricated using standard photolithographic techniques. In addition, the design rule developed from Murray’s law is extended to a simple power-law fluid to investigate whether it is feasible to design biomimetic networks for non-Newtonian liquids. Remarkably, Murray’s law is obeyed for power-law fluids in cylindrical pipes. Although highly promising, the extension of the analysis to rectangular or trapezoidal channels requires much further work. Moreover, it is unclear at this stage whether Murray’s law holds for other non-Newtonian models.

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Paranjape, Sidharth, Susan N. Ritchey, and Suresh V. Garimella. "Impedance-Based Void Fraction Measurement and Flow Regime Identification in Microchannel Flows." In ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/ipack2011-52116.

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Electrical impedance of a two-phase mixture is a function of void fraction and phase distribution. The difference in the electrical conductance and permittivity of the two phases can be exploited to measure electrical impedance for obtaining void fraction and flow regime characteristics. An electrical impedance meter is constructed for the measurement of void fraction in microchannel two-phase flow. The experiments are conducted in air-water two-phase flow under adiabatic conditions. A transparent acrylic test section of hydraulic diameter 780 micrometer is used in the experimental investigation. The impedance void meter is calibrated against the void fraction measured using analysis of images obtained with a high-speed camera. Based on these measurements, a methodology utilizing the statistical characteristics of the void fraction signals is employed for identification of microchannel flow regimes.

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Lee, Sung Jin, Gerald R. Bourne, Xiaoming Chen, W. Gregory Sawyer, and Malisa Sarntinoranont. "Mechanical Characterization of Contact Lenses by Microindentation: Constant Velocity and Relaxation Testing." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192640.

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Mechanical and fluid transport properties of soft contact lenses may influence clinical performance, e.g., on-eye movement, fitting, and wettability, and may be related to the occurrence of complications, e.g. lesions [1, 2]. In the mechanical assessment of soft hydrated materials, indentation is increasingly being used because of its nondestructive methods for testing these material properties allow for multiple tests to be performed on the same sample, which will speed up the design and testing process for hydrogel contact lenses. [3]. Contact lens hydrogels may be described as a biphasic material. The material properties governing biphasic behavior are the Young’s modulus of the solid phase, Poisson ratio’s, and hydraulic permeability which is measure of fluid conductance in porous media. Previous studies of indentation of biphasic media have been completed by Mow and coworkers [4]. Also, computational finite element (FE) models have also been developed [5].

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Hsieh, Chang-Lung, Hao-Tzu Lin, Show-Chuyan Chiang, Chunkuan Shih, Jong-Rong Wang, and Tung-Li Weng. "LAPUR5.2 BWR Stability Analysis in Chinshan Nuclear Power Plant." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89587.

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Boiling water reactors have the unique coupling mechanisms between neutronic and two-phase flow thermal-hydraulic behaviors and may induce instability by unstable power/flow oscillations. At each core reload design, it is important to employ decay ratio for the purpose of analyzing system stability and determining its operating boundary. Making use of LAPUR5.2 and SIMULATE-3 codes, we have established a methodology to conduct such analysis. Comparisons made with vendor’s STAIF results indicated good agreements in decay ratios for Chinshan Nuclear Power Plant Unit 2 Cycle 21 reload design. This research focuses on the parametric sensitivity effect on the variation of decay ratio for different power/flow operating points. Based on the result of sensitivity studies, we presented fractional changes of decay ratios by varying certain important parameters under different power/flow points. It is concluded that density reactivity coefficient, gap conductance and recirculation loop gain on high operating power/flow points have larger fractional change of decay ratio.

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Kendall, Gail E., Peter Griffith, Arthur E. Bergles, and John H. Lienhard. "Small Diameter Effects on Internal Flow Boiling." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24211.

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Abstract Since the 1950’s, the research and industrial communities have developed a body of experimental data and set of analytical tools and correlations for two-phase flow and heat transfer in passages having hydraulic diameter greater than 6 mm or so. These tools include flow regime maps, pressure drop and heat transfer correlations, and critical heat flux limits, as well as strategies for robust thermal management of HVAC systems, electronics, and nuclear power plants. Designers of small systems with thermal management by phase change will need analogous tools to predict and optimize thermal behavior in the mesoscale and smaller sizes. Such systems include a wide range of devices for computation, measurement, and actuation in environments that range from office space to outer space and living systems. This paper examines important proceses that must be considered when channel diameters decrease, including flow distribution issues in single, parallel, and split flows; flow instability in parallel passages; manufacturing tolerances effects; nucleation processes; and wall conductance effects. The discussion focuses on engineering issues for the design of practical systems.

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Reports on the topic "Hydraulic conductance"

Cohen, Shabtai, Melvin Tyree, Amos Naor, Alan N. Lakso, Terence L. Robinson, and Yehezkiel Cohen. Influence of hydraulic properties of rootstocks and the rootstock-scion graft on water use and productivity of apple trees. United States Department of Agriculture, 2001. http://dx.doi.org/10.32747/2001.7587219.bard.

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This one year exploratory project investigated hydraulic architecture of apple dwarfing rootstocks. The hypothesis was that hydraulic conductance is correlated with rootstock vigor. A previous study of trees on three rootstocks in Israel showed that dwarfed trees used less water than un-dwarfed trees. Analysis showed that if the tree maintains leaf water potentials above minimum values, then this implies that the dwarfed trees have lower leaf conductance, which may also be the cause of dwarfing. The current project studied small 2-year old unworked rootstock trees, and full sized trees bearing commercial yields. In both cases hydraulic conductance was determined with two methods - the non-destructive evaporative flux (EF)-leaf water potential (L WP) method, and a destructive method in which water was forced through the plant at known pressure using the "high pressure flow meter" (HPFM). Detailed work allowed measurement of conductance of the rootstock-scion union. This was achieved both with the HPFM and with the EF-LWP methods, the former in the US and the latter in Israel. Direct measurements of leaf conductance were made, and carbon isotope ratios ( d ¹³ C) were determined for leaves sampled at the end of the season. The latter can indicate sustained differences in leaf conductance behavior. HPFM and EF-LWP methods did not give the same results. In the small plants results were similar in magnitude, but not significantly correlated. In large trees, EF- L WP measurements were a fraction of those obtained with the HPFM. The latter indicates that some of the xylem is not normally functional but transports water when pressurized. Additional experimental work targeted this result. Xylem was stained before and after perfusion with water at high pressure. This showed that at least for one rootstock a significant amount of xylem was blocked before perfusion. The "air method" for determining xylem vessel properties was improved and employed. Length, radius and density of xylem vessels of different rootstocks were found to be similar, and significant differences found were not clearly related to rootstock vigor. Measurements in the commercial orchard in Israel showed that the graft union in a dwarfing rootstock was a large obstacle for water transport (i.e. had a high resistance). This apparently led to low leaf conductance to water vapor, as indicated by lower d ¹³ C, which implies low internal CO ₂ concentrations. In the US orchard, d ¹³ C in 2001 was correlated with rootstock vigor, and significant differences were found in leaf conductance. However, the d ¹³ C differences were not observed in 2002, were opposite to those found in the Israeli orchard, and measurements of the graft union with the HPFM did not find large resistances. We speculate that the graft union is not necessarily a large impediment to water transport unless the scion starts to separate from the rootstock. It was concluded that significant differences in hydraulic conductance exist between different dwarfing rootstocks. These differences may be caused by differences in xylem properties and in the degree of cavitation, as well as resistance in the graft union. However, no general relationship to rootstock vigor was found. Therefore, hydraulic conductance alone cannot explain dwarfing, but may be one of two or more factors that lead to dwarfing. Future work should integrate more factors with hydraulic relations, e.g. nutrient and solute transport and production of hormones.

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Shani, Uri, Lynn Dudley, Alon Ben-Gal, Menachem Moshelion, and Yajun Wu. Root Conductance, Root-soil Interface Water Potential, Water and Ion Channel Function, and Tissue Expression Profile as Affected by Environmental Conditions. United States Department of Agriculture, October 2007. http://dx.doi.org/10.32747/2007.7592119.bard.

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Constraints on water resources and the environment necessitate more efficient use of water. The key to efficient management is an understanding of the physical and physiological processes occurring in the soil-root hydraulic continuum.While both soil and plant leaf water potentials are well understood, modeled and measured, the root-soil interface where actual uptake processes occur has not been sufficiently studied. The water potential at the root-soil interface (yᵣₒₒₜ), determined by environmental conditions and by soil and plant hydraulic properties, serves as a boundary value in soil and plant uptake equations. In this work, we propose to 1) refine and implement a method for measuring yᵣₒₒₜ; 2) measure yᵣₒₒₜ, water uptake and root hydraulic conductivity for wild type tomato and Arabidopsis under varied q, K⁺, Na⁺ and Cl⁻ levels in the root zone; 3) verify the role of MIPs and ion channels response to q, K⁺ and Na⁺ levels in Arabidopsis and tomato; 4) study the relationships between yᵣₒₒₜ and root hydraulic conductivity for various crops representing important botanical and agricultural species, under conditions of varying soil types, water contents and salinity; and 5) integrate the above to water uptake term(s) to be implemented in models. We have made significant progress toward establishing the efficacy of the emittensiometer and on the molecular biology studies. We have added an additional method for measuring ψᵣₒₒₜ. High-frequency water application through the water source while the plant emerges and becomes established encourages roots to develop towards and into the water source itself. The yᵣₒₒₜ and yₛₒᵢₗ values reflected wetting and drying processes in the rhizosphere and in the bulk soil. Thus, yᵣₒₒₜ can be manipulated by changing irrigation level and frequency. An important and surprising finding resulting from the current research is the obtained yᵣₒₒₜ value. The yᵣₒₒₜ measured using the three different methods: emittensiometer, micro-tensiometer and MRI imaging in both sunflower, tomato and corn plants fell in the same range and were higher by one to three orders of magnitude from the values of -600 to -15,000 cm suggested in the literature. We have added additional information on the regulation of aquaporins and transporters at the transcript and protein levels, particularly under stress. Our preliminary results show that overexpression of one aquaporin gene in tomato dramatically increases its transpiration level (unpublished results). Based on this information, we started screening mutants for other aquaporin genes. During the feasibility testing year, we identified homozygous mutants for eight aquaporin genes, including six mutants for five of the PIP2 genes. Including the homozygous mutants directly available at the ABRC seed stock center, we now have mutants for 11 of the 19 aquaporin genes of interest. Currently, we are screening mutants for other aquaporin genes and ion transporter genes. Understanding plant water uptake under stress is essential for the further advancement of molecular plant stress tolerance work as well as for efficient use of water in agriculture. Virtually all of Israel’s agriculture and about 40% of US agriculture is made possible by irrigation. Both countries face increasing risk of water shortages as urban requirements grow. Both countries will have to find methods of protecting the soil resource while conserving water resources—goals that appear to be in direct conflict. The climate-plant-soil-water system is nonlinear with many feedback mechanisms. Conceptual plant uptake and growth models and mechanism-based computer-simulation models will be valuable tools in developing irrigation regimes and methods that maximize the efficiency of agricultural water. This proposal will contribute to the development of these models by providing critical information on water extraction by the plant that will result in improved predictions of both water requirements and crop yields. Plant water use and plant response to environmental conditions cannot possibly be understood by using the tools and language of a single scientific discipline. This proposal links the disciplines of soil physics and soil physical chemistry with plant physiology and molecular biology in order to correctly treat and understand the soil-plant interface in terms of integrated comprehension. Results from the project will contribute to a mechanistic understanding of the SPAC and will inspire continued multidisciplinary research.

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