Academic literature on the topic 'Hydraulic architecture'
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Journal articles on the topic "Hydraulic architecture"
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Sperry, John. "Hydraulic architecture of palms." Giornale botanico italiano 129, no. 1 (January 1995): 482–90. http://dx.doi.org/10.1080/11263509509436166.
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Vanderborght, Jan, Valentin Couvreur, Felicien Meunier, Andrea Schnepf, Harry Vereecken, Martin Bouda, and Mathieu Javaux. "From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models." Hydrology and Earth System Sciences 25, no. 9 (September 6, 2021): 4835–60. http://dx.doi.org/10.5194/hess-25-4835-2021.
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Abstract. Root water uptake is an important process in the terrestrial water cycle. How this process depends on soil water content, root distributions, and root properties is a soil–root hydraulic problem. We compare different approaches to implement root hydraulics in macroscopic soil water flow and land surface models. By upscaling a three-dimensional hydraulic root architecture model, we derived an exact macroscopic root hydraulic model. The macroscopic model uses the following three characteristics: the root system conductance, Krs, the standard uptake fraction, SUF, which represents the uptake from a soil profile with a uniform hydraulic head, and a compensatory matrix that describes the redistribution of water uptake in a non-uniform hydraulic head profile. The two characteristics, Krs and SUF, are sufficient to describe the total uptake as a function of the collar and soil water potential, and water uptake redistribution does not depend on the total uptake or collar water potential. We compared the exact model with two hydraulic root models that make a priori simplifications of the hydraulic root architecture, i.e., the parallel and big root model. The parallel root model uses only two characteristics, Krs and SUF, which can be calculated directly following a bottom-up approach from the 3D hydraulic root architecture. The big root model uses more parameters than the parallel root model, but these parameters cannot be obtained straightforwardly with a bottom-up approach. The big root model was parameterized using a top-down approach, i.e., directly from root segment hydraulic properties, assuming a priori a single big root architecture. This simplification of the hydraulic root architecture led to less accurate descriptions of root water uptake than by the parallel root model. To compute root water uptake in macroscopic soil water flow and land surface models, we recommend the use of the parallel root model with Krs and SUF computed in a bottom-up approach from a known 3D root hydraulic architecture.
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Leifeld, Roland, Milos Vukovic, and Hubertus Murrenhoff. "Hydraulic Hybrid Architecture for Excavators." ATZoffhighway worldwide 9, no. 3 (May 25, 2016): 44–49. http://dx.doi.org/10.1007/s41321-016-0523-9.
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Carvalho, Mónica R., Robert Turgeon, Thomas Owens, and Karl J. Niklas. "The hydraulic architecture of Ginkgo leaves." American Journal of Botany 104, no. 9 (September 2017): 1285–98. http://dx.doi.org/10.3732/ajb.1700277.
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Hacke, Uwe G. "Irradiance-induced changes in hydraulic architecture." Botany 92, no. 6 (June 2014): 437–42. http://dx.doi.org/10.1139/cjb-2013-0200.
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The ability to acclimate to a range of light regimes is important, given that shady understory habitats can receive only a fraction of the light available at the top of the canopy. Sun and shade leaves are known to differ in their set of biochemical and morphological characteristics. In recent years, much has also been learned about the effect of shade on xylem structure and function. Several studies found that shaded plants had narrower xylem conduits than plants growing in full sun. Among the most notable responses induced by shade is a shift of xylem vulnerability to cavitation. Shaded plants are typically more vulnerable to cavitation than plants exposed to full light. This appears to coincide with the construction of weaker intervessel and intertracheid pit membranes in shade. Before entering and after exiting the xylem, water moves through living cells in roots and leaves, respectively. This nonvascular pathway can be modified by aquaporins. Rapid changes in root and leaf hydraulic conductance in response to changes in light and transpirational demand have been described. The role of aquaporins in these responses is discussed.
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Gaiola, Andrea, Barbara Zardin, Paolo Casoli, Massimo Borghi, Francesca Mazzali, Francesco Pintore, and Stefano Fiorati. "The Hydraulic Power Generation and Transmission on Agricultural Tractors: feasible architectures to reduce dissipation and fuel consumption – Part I." E3S Web of Conferences 197 (2020): 07009. http://dx.doi.org/10.1051/e3sconf/202019707009.
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This paper is aimed at investigating the benefits in terms of energy efficiency of new electro-hydraulic architectures for power distribution systems of a medium-size agricultural tractor, with a focus on the hydraulic high-pressure circuit. The work is part of a wider industrial research project called TASC (Smart and Clean Agricultural Tractors [1]). Traditional and alternative architectures have been modelled and energetically compared through simulation, using a lumped parameter approach. Experimental data previously acquired have been used to validate the models and to replicate real working conditions of the machine in the simulation environment. A typical on-field manoeuvre has been used as duty cycle, to perform an effective energetic analysis. The standard hydraulic circuit is a multi-users load sensing system that uses a single variable displacement pump to feed steering, trailer brake and auxiliary utilities in that order. The key idea of the proposed solutions is the separation of steering from the other implements, to optimize the entire energy management. In particular, the paper investigates new and flexible solutions for the auxiliary utilities, including an electro-hydraulic load sensing architecture with variable pump margin, an electronic flow matching and flow sharing architecture, and an electronic strategy for automatic pressure compensation. The simulation results show that good energy saving can be achieved with the alternative architectures, so that physical prototyping of the most promising solutions will be realized as next step of the project.
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Ishii, Hiroaki, Wakana Azuma, Ayumi Shiraki, and Keiko Kuroda. "Hydraulic Architecture and Function of Tall Trees." Journal of the Japanese Forest Society 99, no. 2 (2017): 74–83. http://dx.doi.org/10.4005/jjfs.99.74.
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Darlington, Alan B., and Michael A. Dixon. "The hydraulic architecture of roses (Rosa hybrida)." Canadian Journal of Botany 69, no. 4 (April 1, 1991): 702–10. http://dx.doi.org/10.1139/b91-095.
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The presence of an abscission zone in the stem of greenhouse roses (Rosa hybrida) between the vegetative and reproductive components was verified. This led to a description of the hydraulic architecture of the rose stem. The structural aspects of the xylem conducting system in stem, abscission zone and peduncle were examined to define their relative roles in the delivery of water via the stem to the transpiring plant surfaces and the extent to which their functional capacity may be influenced by environmental variables such as humidity. The stem exhibited a highly developed xylem with many large-diameter tracheary elements. Contrary to this the distal segment of the peduncle was poorly vascularized. The remainder of the peduncle, which included the abscission zone, was a transition between these two extremes. The abscission zone was a site of reduced hydraulic conductance that was not due to a reduction in the number or size of xylem conduits but to changes in the alignment of the elements. The variable conductances across the abscission zone and peduncle regions may play an important role in floral development and the response of the plant to water stress. Rose plants grown at constantly high humidity (77% RH) did not exhibit significantly different internal anatomical features of the xylem conducting system relative to roses grown in ambient, uncontrolled humidity (30 to 60% RH). Key words: abscission zone, hydraulic conductance, humidity.
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Martínez-Vilalta, Jordi, Anna Sala, and Josep Piñol. "The hydraulic architecture of Pinaceae – a review." Plant Ecology (formerly Vegetatio) 171, no. 1/2 (2004): 3–13. http://dx.doi.org/10.1023/b:vege.0000029378.87169.b1.
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Christoffersen, Bradley O., Manuel Gloor, Sophie Fauset, Nikolaos M. Fyllas, David R. Galbraith, Timothy R. Baker, Bart Kruijt, et al. "Linking hydraulic traits to tropical forest function in a size-structured and trait-driven model (TFS v.1-Hydro)." Geoscientific Model Development 9, no. 11 (November 24, 2016): 4227–55. http://dx.doi.org/10.5194/gmd-9-4227-2016.
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Abstract. Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the diversity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media approach to modeling plant hydraulics in which all parameters of the constitutive equations are biologically interpretable and measurable plant hydraulic traits (e.g., turgor loss point πtlp, bulk elastic modulus ε, hydraulic capacitance Cft, xylem hydraulic conductivity ks,max, water potential at 50 % loss of conductivity for both xylem (P50,x) and stomata (P50,gs), and the leaf : sapwood area ratio Al : As). We embedded this plant hydraulics model within a trait forest simulator (TFS) that models light environments of individual trees and their upper boundary conditions (transpiration), as well as providing a means for parameterizing variation in hydraulic traits among individuals. We synthesized literature and existing databases to parameterize all hydraulic traits as a function of stem and leaf traits, including wood density (WD), leaf mass per area (LMA), and photosynthetic capacity (Amax), and evaluated the coupled model (called TFS v.1-Hydro) predictions, against observed diurnal and seasonal variability in stem and leaf water potential as well as stand-scaled sap flux. Our hydraulic trait synthesis revealed coordination among leaf and xylem hydraulic traits and statistically significant relationships of most hydraulic traits with more easily measured plant traits. Using the most informative empirical trait–trait relationships derived from this synthesis, TFS v.1-Hydro successfully captured individual variation in leaf and stem water potential due to increasing tree size and light environment, with model representation of hydraulic architecture and plant traits exerting primary and secondary controls, respectively, on the fidelity of model predictions. The plant hydraulics model made substantial improvements to simulations of total ecosystem transpiration. Remaining uncertainties and limitations of the trait paradigm for plant hydraulics modeling are highlighted.
Dissertations / Theses on the topic "Hydraulic architecture"
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Vukovic, Milos, Roland Leifeld, and Hubertus Murrenhoff. "STEAM – a hydraulic hybrid architecture for excavators." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200445.
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During the past three years the Institute for Fluid Power Drives and Controls in Aachen has developed a new hydraulic system for mobile machinery called STEAM. The system represents a new step in excavator hydraulics, as it aims to reduce both the hydraulic system losses as well as those of the internal combustion engine by using a hybrid hydraulic architecture with accumulators. Starting with initial simulation studies the development has been followed by scaled test bench measurements and has progressed to a full scale validation using an 18 t excavator. The following publication aims to summarise the results obtained thus far with the aim of making them available to industry and encouraging their implementation in future applications.
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Boulineau, Sheryl Taillon. "East Lake Meadows : hydrologic strategies for architecture." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/23366.
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Pingarrón, Alvarez Victoria I. "Performance analysis of hydraulic lime grouts for masonry repair." Connect to PDF file, 2006. http://repository.upenn.edu/cgi/viewcontent.cgi?article=1013&context=hp_theses.
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Ammounah, Anas. "Architecture de contrôle pour un robot humanoïde à actionnement hydraulique." Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG056.
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HYDROïD est le premier robot humanoïde à actionnement hydraulique en Europe. Cette plateforme de recherche a été créée pour émuler le corps humain. L'émulation du corps humain est importante car l'objectif du robot humanoïde du futur est de coopérer et d'interagir avec les humains, voire de les remplacer dans des scénarios dangereux. Cette interaction nécessite des aspects de sécurité. L'émulation et le fait de disposer d'un robot anthropomorphe comme le corps humain simplifient la réalisation de cet objectif. De nombreux aspects de l'émulation ont déjà été réalisés, l'actionnement du robot émule les muscles humains, les mécanismes hybrides émulent la cinématique humaine et l'effet agoniste-antagoniste, la conception mécanique du robot émule la morphologie fine et la distribution de masse du corps humain, et le flux hydraulique émule le flux sanguin à l'intérieur du corps.Dans cette thèse, nous avons cherché à émuler l'architecture du système nerveux humain, c'est-à-dire la structure physique, la transmission et le traitement de l'information. Nous avons proposé une architecture de contrôle en couches pour HYDROïD. Une architecture distribuée avec 12 contrôleurs locaux a été conçue pour être placée sur le corps du robot afin de contrôler 36 articulations cinématiques actionnées hydrauliquement. Un PC central doté d'un système d'exploitation en temps réel gère le mouvement du corps entier par le biais d'un intergiciel en temps réel et de la communication EtherCAT. Chaque contrôleur local est une unité informatique intégrée complète permettant de contrôler le robot au niveau des articulations. Un pilote personnalisé a été construit pour contrôler l'actionnement hydraulique. Nous avons étudié deux approches à ce niveau, en utilisant une approche à boucle unique et une approche multithreadingHYDROïD is the first humanoid robot with hydraulic control in Europe. This research platform was created to emulate the human body. The emulation of the human body is important because the objective of the humanoid robot in the future is to cooperate and interact with humans, and even to replace them in dangerous scenarios. This interaction requires safety aspects. Emulation and having an anthropomorphic robot like the human body simplifies the achievement of this goal. Many aspects of emulation have already been realized, the actuation of the robot emulates human muscles, the hybrid mechanisms emulate human kinematics and agonist-antagonist effect, the mechanical design of the robot emulates the thin morphology and mass distribution of the human body, and the hydraulic flow emulates the blood flow inside the body.In this thesis, we have sought to emulate the architecture of the human nervous system, i.e., the physical structure, transmission, and processing of information. We proposed a layered control architecture for HYDROïD. A distributed architecture with 12 local controllers has been designed to be placed on the body of the robot to control 36 hydraulically operated kinematic joints. A central PC with a real-time operating system manages the whole-body motion through real-time middleware and EtherCAT communication. Each local controller is a complete integrated computing unit to control the robot at the joint level. A custom driver was built to control the hydraulic actuation. We investigated two approaches at this level, using a single-loop approach and a multi-threading approach
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Vinya, Royd. "Stem hydraulic architecture and xylem vulnerability to cavitation for miombo woodlands canopy tree species." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:9028b995-5379-4969-8a7b-59a7aa7ab533.
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Africa's miombo woodlands constitute one of the most important dry tropical forests on earth, yet the hydraulic function of these woodlands remains poorly researched. Given the current predictions of increased aridity by the end of this century in the miombo ecoregion, understanding the likely response of miombo woodlands tree species to water stress is crucial in planning adaptation strategies. Predicting the response of miombo woodlands to future climate trends is hampered by a lack of knowledge on the physiology of the common miombo woodlands tree species. In particular, plant-water relations for this woodlands type are not well understood. An understanding of plant-water relations for this woodlands type will provide insights into how water limits tree species distribution in this ecosystem. This will also improve our prediction model on the likely response of this ecosystem to predicted climate change. For this reason, the overall objective of this research was to evaluate the hydraulic architecture and xylem vulnerability to cavitation for nine principal miombo woodlands tree species differing in drought tolerance ability and habitat preference. This was achieved by; examining the hydraulic properties and evaluating the extent to which each hydraulic design was vulnerable to water stress-induced xylem cavitation; investigating how seasonal changes in plant-water relations influences seasonal patterns of leaf display and; analyzing the relationship between stem hydraulic supply and leaf functional traits related to drought tolerance ability. This research has found that drought-intolerant tree species with mesic specialization have more efficient stem hydraulic systems than co-occurring habitat broad ranging species. Broad ranging tree species attain wider habitat distribution by adjusting their hydraulic supply in response to changing ecosystem water availability. The finding that hydraulic properties differ significantly between tree species with contrasting habitat preference suggests that tree hydraulic design may have some adaptive ecological role in influencing species habitat preferences in miombo woodlands. The evaluation of xylem vulnerability to cavitation revealed that mesic specialized tree species were more vulnerable to water stress-induced cavitation than habitat broad ranging tree species. Vulnerability to cavitation in individuals from the same broad-ranging species growing in contrasting habitats showed only marginal and statistically insignificant (P > 0.05) differences between wet and dry sites. In the investigation of the influence of seasonal changes in stem water relations on seasonal leaf display, seasonal rhythms in stem water status were found to exert significant controls on leaf phenology. Mesic specialists had strong stem water controls throughout the year in comparison to broad ranging tree species. An analysis of the relationship between stem hydraulic supply and leaf functional traits suggests that stem hydraulic supply constrains leaf biomass allocation patterns among miombo tree species. Mesic specialists tend to invest more in leaf longevity than broad ranging tree species. This thesis has uncovered some interesting relationships between plant-water-relations and the distribution of miombo woodlands tree species. These results lead to the conclusion that in an event of increased ecosystem drying under future climate trends, tree species with mesic specialisation are at a greater risk of experiencing cavitation related species mortality than broad ranging ones.
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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 PhilosophyDepartment 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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Lechthaler, Silvia. "The hydraulic architecture of the plants: study of the allometric relations in stem and leaves." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3426838.
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The xylem in plants is formed by interconnected dead cells that allow the flow of water from the roots to the leaves. The ascent of sap is mainly passive and it is driven by water evaporation from the mesophyll cell walls in the leaf. The water evaporation generates capillary suction on the menisci at the micro-porous of cell walls, causing negative hydrostatic pressure that propagates down the water column in the xylem. Due to plants grow in height the length of the hydraulic path increases progressively posing the question whether the hydraulic resistance increases accordingly. There is evidence that plants have evolved xylem structures that compensate the possible increase of the hydraulic resistance imposed by path length, namely the tip-to-base conduits widening. Conduits widening has been reported in several species, both angiosperms and conifers, showing that the degree of widening from tip to the base of the stem is very similar among species, or in other words, that plants converge towards a universal xylem structure. Nevertheless, several points on the hydraulic architecture of plants remain to be elucidated.
A largely debated point is whether xylem anatomical traits (e.g. the absolute cell size) change with climatic conditions. Moreover, whether and how the conduits widening in the stem may affect the xylem anatomy of the leaf is still not fully understood. This PhD project aims to widen our understanding of the allometric relations of leaves and stem xylem, considering how the environmental conditions and the height of the plant affect the hydraulic architecture of the water transport system.
A methodological study (Study 1) has been performed on the xylem tissue of stems of Acacia trees grown in different water availability conditions. The main result was that, once the anatomical data were standardized for the tree height, the hydraulic architecture of the xylem did not change in relation to the environmental conditions.
Two studies have been performed on the hydraulic architecture of leaves. The main focus was on the anatomical traits of the xylem conduits in relation to the leaf dimensions and/or the position in the tree crown (height from the base of the stem). The main results were that the xylem traits scaled with the leaf area independently by the position in the crown (Study 2). A fine analysis of the leaf midrib (i.e. major leaf vein) has shown a rigid hydraulic architecture and tissues coordination (Study 3) that was well predicted by the distance from the leaf tip. Both studies showed that the dimensions of the terminal veins were conserved among leaves and within leaf suggesting that the hydraulic architecture of the xylem in the leaf evolved in a way to guarantee an equal distribution of the hydraulic resistances (and thus of the water) among leaves and within the leaf lamina.
Finally, we implemented the anatomical data of both stem and leaf into a hydraulic model to assess the distribution of resistances along the hydraulic path to evaluate how the anatomy of the transport system affects the physiology of the entire tree (Study 4).
This thesis has highlighted that the path length (i.e. the height of the plant and the dimensions of the leaf) is the main factor affecting the hydraulic architecture of the tree. The conduit dimension in both stem and leaf are determined by the distance from the terminal parts, stem apex or leaf tip respectively. Climatic conditions resulted to have marginal (non-significant) effect on the stem anatomical traits. In the leaf, the dimensions of the xylem conduits are statistically invariant with changes in plant size. This rigid hydraulic architecture of the tree, from the stem to the leaf, allows minimizing the effect of the path length on the hydraulic resistance, confining nearly the whole gradient of water potential within the leaves.Lo xilema nelle piante è formato da cellule morte interconnesse che consentono il flusso di acqua dalle radici alle foglie. L'ascesa della linfa è principalmente passiva ed è guidata dall'evaporazione dell'acqua dalle pareti cellulari del mesofillo nella foglia. L'evaporazione dell'acqua genera un'aspirazione capillare sui menischi a livello dei micro-pori delle pareti cellulari, causando una pressione idrostatica negativa che si propaga lungo la colonna d'acqua nello xilema. A causa dell’aumento in altezza delle piante, la lunghezza del percorso idrico aumenta progressivamente ponendo la domanda se la resistenza idraulica aumenta di conseguenza. Vi è evidenza che le piante hanno evoluto strutture xilematiche che compensano il possibile aumento della resistenza idraulica imposta dall'aumento della lunghezza del percorso, come ad esempio l'allargamento dei condotti dalla punta alla base. L’allargamento dei condotti è stato osservato in diverse specie, sia angiosperme sia conifere, dimostrando che il grado di allargamento dalla punta alla base dello stelo è molto simile tra le specie, o in altre parole, che le piante convergono verso una struttura xilema universale. Tuttavia, restano da chiarire diversi punti sull'architettura idraulica delle piante. Un punto largamente dibattuto è se tratti anatomici dello xilema (ad esempio la dimensione assoluta delle cellule) cambiano con le condizioni climatiche. Inoltre, se e come i condotti che si allargano nello stelo possano influenzare l'anatomia dello xilema della foglia non è ancora completamente compreso. Il progetto di questo dottorato mira ad ampliare la nostra comprensione delle relazioni allometriche nello xilema delle foglie e del fusto, considerando come le condizioni ambientali e l'altezza della pianta possano influenzare l'architettura idraulica del sistema di trasporto dell'acqua. Uno studio metodologico (Studio 1) è stato eseguito sul tessuto xilematico di fusti di alberi di acacia cresciuti in diverse condizioni di disponibilità idrica. Il risultato principale è stato che, una volta che i dati anatomici sono stati standardizzati per l'altezza dell'albero, l'architettura idraulica dello xilema non è cambiata in relazione alle condizioni ambientali. Sono stati eseguiti due studi sull'architettura idraulica delle foglie. L'obiettivo principale degli studi riguardava i tratti anatomici dei condotti dello xilema in relazione alle dimensioni della foglia e / o alla posizione nella chioma dell'albero (altezza dalla base del fusto). Dai risultati si evince che i tratti dello xilema si ridimensionano in base all'area fogliare indipendentemente dalla posizione nella chioma (Studio 2). Un'analisi fine della nervatura principale della foglia ha mostrato una rigida architettura idraulica e la coordinazione dei tessuti (Studio 3), ben predetta dalla distanza dalla punta della foglia. Entrambi gli studi hanno dimostrato che le dimensioni delle vene terminali sono conservate tra le foglie e all'interno della stessa foglia, suggerendo che l'architettura idraulica dello xilema si è evoluta in modo da garantire distribuzione omogenea delle resistenze idrauliche (e quindi dell'acqua) tra le foglie e lungo la lamina fogliare. Infine, abbiamo implementato i dati anatomici di fusto e foglia in un modello idraulico per stimare la distribuzione delle resistenze lungo il percorso idraulico per valutare in che modo l'anatomia del sistema di trasporto influisca sulla fisiologia dell'intero albero (Studio 4). Questa tesi ha evidenziato che la lunghezza del percorso (vale a dire l'altezza della pianta e le dimensioni della foglia) è il fattore principale che influenza l'architettura idraulica dell'albero. La dimensione del condotto sia nel fusto che nella foglia è determinata dalla distanza dalle parti terminali, rispettivamente l'apice del fusto o la punta della foglia. Le condizioni climatiche risultano avere un effetto marginale (non significativo) sui tratti anatomici del fusto e nella foglia, le dimensioni dei condotti dello xilema sono statisticamente indipendenti rispetto alle variazioni nelle dimensioni della pianta. Questa rigida architettura idraulica dell'albero, dal fusto alla foglia, consente di minimizzare l'effetto della lunghezza del percorso sulla resistenza idraulica, confinando quasi l'intero gradiente del potenziale idrico all'interno delle foglie.
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Palacios, Jonathan, Erik Maquera, and Carlos Toledo. "Hydraulic Technology, Agricultural Expansion, And Non-Monumental Settlements During The Lima Period." Pontificia Universidad Católica del Perú, 2016. http://repositorio.pucp.edu.pe/index/handle/123456789/113331.
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The purpose of this article is to provide new evidence that contributes to an understanding of the processes that led to the creation of Late Lima monumental centers. is evidence comes from the Huachipa plains and non-monumental settlements located in the middle Rimac Valley such as San Antonio-Huachipa, El Golf de Huampaní (also known as El Vallecito), and Pancha Paula located in the Chillon valley.El propósito de este trabajo es aportar nueva evidencia que contribuya a explicar los procesos que dieron origen a los centros monumentales Lima Tardío, con evidencia procedente de la llanura de Huachipa y asentamientos no monumentalesdel valle medio del Rímac como San Antonio-Huachipa, El Golf de Huampaní (en adelante El Vallecito) y Pancha Paula en el valle del Chillón.
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Azolibe, Ifeanyi. "Architecture of a cyber-physical system for aircraft fuel control systems tests." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/8503/.
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The aircraft fuel control system makes sure an engine has the precise amount of fuel required to generate power and thrust for every stage of flight. It therefore plays a role in determining the economics of flight. In order to maintain the economic equilibrium of performance and flight safety, it undergoes a Maintenance Repair or Overhaul (MRO) service after several hours of operation. A critical aspect of the MRO service is the test performed to validate the airworthiness of a fuel control system before it returns to service. The test of aircraft fuel control systems is human-centric by design. The operator uses a network of test systems to generate in-flight conditions similar to what the Unit-Under-Test (UUT) experiences on-board an aircraft engine, then performs tests to validate and verify its airworthiness. Thereafter, test results are recorded for regulatory compliance reasons after each test is performed successfully. An analysis of the test specification for the UUT involved in this study revealed 90% of an operator’s touch-time is automatable. The functions of control, data processing, data entry and supervision must be achieved automatically if they are to be performed autonomously by a cyber-physical test system. But the automation of these activities at the micro level does not guarantee their autonomous execution at a macro level by such a cyber-physical system composed of the network of test systems. Therefore, knowledge of a multidisciplinary array of fundamental concepts and how they can be fused to execute the test of aircraft fuel control systems autonomously, have been developed as presented in this thesis. For the function of process control, the response of the processes used to set test conditions is ~ 50Hz, five times the rate of process responses reported in typical process industries where automation of process control have been achieved. As a result of this fundamental knowledge, the design of the architectures for the functions of control and data processing is an asynchronous one. Noting that none of the data is fed back through a network like the case of Networked Control Systems or Supervisory Control and Data Acquisition Systems. The realization of the control functions for each process used to set test conditions is based on control laws synthesized through modelling of their respective actuation mechanisms. Of the three models developed, a 2nd order model has been identified as been representative of the dynamic and steady-state characteristics of each actuation mechanism. A typical actuation mechanism contains a high number of masses and springs whose physical modelling resulted in a model of 12th order. This model is highly unrepresentative of the transient and steady-state response observed in the process due to difficulty in estimating the internal parameters of respective actuators. A linear model synthesized from the calibration data of each actuation mechanism has also been investigated and found to be too ideal. Its response is unrepresentative of the dynamic characteristics of the actuation mechanisms. The processes used to generate test conditions have been set simultaneously using a network of PID controllers. The controllers’ gains are an order of ten less than what they were for the sequential set up of test conditions due the fact that there are interactions between the processes inside a UUT. Fundamentally however, this Thesis demonstrates an asynchronous architecture for the control function, which enables a pseudo steady-state execution of tests. In-practice, this has the potential to reduce the time it takes to perform a test by one-third. The function of supervision has been developed in the form of a Fault Detection Isolation and Recovery capability within the cyber-physical test system. The architecture for this function is designed based on minimalizing the constraint of the period of recoverability (PoR), where the deviations from normal operation need to be detected, the outcomes they could result to—diagnosed and recovery strategies executed to prevent test systems or the UUT deviate from normal operation, using measurements acquired in a time < PoR. Oscillations and offsets have been identified as the major causes of deviations in subsystems during the test of the aircraft fuel control system in this study. In order to diagnose a deviation, a fuzzy inference engine has been developed over a Fault Tree Analysis approach because it makes the automation of domain knowledge needed to realize the supervision function effective. Nevertheless, the contributions of this thesis are the knowledge gaps it uncovers and the formalized approaches it proposes in the form of architectures to plug these gaps. It provides a direction on how to actualize not only the concept of automation, but the realization of a cyber-physical system to test an aircraft fuel control systems. It is the architecture of a singular system capable of executing the functions performed by an operator autonomously, and surpassing what can be achieved in the case of simultaneous process control, automated detection and isolation of a critical deviations under the period of recoverability, that is the fundamental contribution of this thesis. So that in the not so distant future the test of aircraft fuel control systems can be performed by machines.
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Dias, Arildo de Souza 1979. "Atributos foliares e anatômicos do xilema em espécies de árvores e lianas da Floresta Atlântica." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314996.
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Orientadores: Fernando Roberto Martins, Rafael Silva OliveiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Compreender como espécies de plantas diferenciam-se em relação a atributos funcionais para aquisição e utilização de recursos, e se a relação entre esses atributos varia em função de diferenças ambientais, como pluviosidade total e sazonalidade, e uma forma de construir uma ecologia mais preditiva no contexto das mudanças climáticas globais. Nesta tese investigamos como arvores e lianas se diferenciam em relação a atributos funcionais da folha dos ramos. Analisamos-nos se o relacionamento entre esses atributos diferia considerando a variação de pluviosidade e sazonalidade de duas fitofiosionomias da Floresta Atlântica, a floresta ombrofila densa (FO) e a floresta estacional semedicidua (FS). Encontramos diferenças não são na amplitude, mas também na forca do relacionamento entre os atributos funcionais foliares estudados. Essas diferenças parecem ser determinadas pela diferença ambiental entre as duas florestas estudadas e por características intrínsecas do habito de crescimento de lianas e arvores. A anatomia do xilema das espécies de lianas e arvores da FO difere em relação à das espécies da FS, mesmo quando consideramos o parentesco filogenético. Por investir pouco em tecidos de sustentação esperava-se menor conteúdo de lignina nos ramos de lianas, entretanto nosso resulto foi o oposto. Encontramos a razão S/G dos monômeros syringil e guaiacil que compõe a lignina menor que um para duas espécies de lianas. Indicando que ha maior deposição de lignina em vasos de xilema do que em fibras. Esse fato pode estar relacionado à maior eficiência em condutividade hidráulica de lianas ou a requerimentos biomecânicos específicos dos ramos de lianas. Em particular, ressalta-se o fato de que lianas foram mais eficientes em captar luz (menor MFA) e tiveram maior condutividade hidráulica potencial (Kp) do que arvores na FS. A maior competitividade de lianas frente arvores apenas na FS tem implicação importante no cenário de mudanças climáticas
Abstract: Understanding how plant species differentiated in functional traits for resources acquisition and use, and if the relationships among those traits vary in according with environmental characteristics such as rainfall and seasonality, could lead to a more predictive science in the context of global change. Here we investigate how trees and lianas differ in leaf and xylem anatomical traits related to water transport and hydraulic architecture. We analyze the relationships among those traits taking into account the variation in rainfall and seasonality between two types of Atlantic Forest, semediciduous seasonal forest (SF) and the dense ombrophilous forest (OF). We found differences not only in range, but in the strength of the relationship among leaf functional traits, which in turn could be related to environmental differences between the two forests studied. The xylem anatomy of lianas and tree species of OF differ compared to species of SF despite taking to account the phylogenetic relatedness. Since lianas have low investment in support tissues we expected lower lignin content in the branches of lianas. However, we found the opposite pattern. Another unexpected result found for two liana species was the ratio to the monomers syringyl and guayacil present at lignin (S/G) lower than one. This result indicates that there is more deposition of lignin in xylem vessel walls than fibers, what in turn would be linked to greater efficiency in hydraulic conductivity of lianas or to specific biomechanical requirements of the branches of lianas. In particular, we highlighted the fact that liana species are more efficient in light acquisition (lower LMA) and had higher hydraulic conductivity (Kp) relative to trees just in the SF. These lianas competitive advantages over trees have important implications in the context of climatic changes
Doutorado
Biologia Vegetal
Doutor em Biologia Vegetal
Books on the topic "Hydraulic architecture"
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Canal architecture. Princes Risborough: Shire, 1986.
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Belidor. The mills of Bélidor (Architecture hydraulique, part 1, book 2). Watford, Herts, England: International Molinological Society, 2003.
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Water architecture in South Asia: A study of types, development, and meanings. Leiden: Brill, 2002.
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Puche, José. Patrimonio hidráulico del Bajo Aragón turolense: Usos históricos del agua. Zaragoza: Prames, 2009.
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Caralt, David. Agualuz: De pirotecnias a mundos flotantes : visiones de Carles Buïgas. Madrid: Siruela, 2010.
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Sellin, Arne. Variation in hydraulic architecture of Picea Abies (L.) Karst. trees grown under different environmental conditions. Tartu: Universitas Tartuensis, 1994.
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Nawwār, Sāmī Muḥammad. al- Munshaʾāt al-māʾīyah bi-Miṣr mundhu al-fatḥ al-Islāmī wa-ḥattá nihāyat al-ʻAṣr al-Mamlūkī: Dirāsah atharīyah miʻmārīyah. al-Iskandarīyah: Dār al-Wafāʾ li-Dunyā al-Ṭibāʻah wa-al-Nashr, 1999.
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Oldani, Andrea. Acque e paesaggi d'invenzione: Descrizione, meraviglia e nuova interpretazione di infrastrutture e architetture dell'acqua. Melfi (Italia): Libria, 2020.
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Javier, Ibáñez Fernández, ed. Patrimonio hidráulico en Aragón. Zaragoza: Aqua, 2008.
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Les architectes de l'eau en Provence: De la Renaissance au XXe siècle. Arles: Actes sud, 2011.
Find full textBook chapters on the topic "Hydraulic architecture"
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Rust, S., D. Lüttschwager, and R. F. Hüttl. "Hydraulic architecture of Scots pine." In Nutrients in Ecosystems, 111–18. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9022-8_7.
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Hacke, Uwe G., Barbara Lachenbruch, Jarmila Pittermann, Stefan Mayr, Jean-Christophe Domec, and Paul J. Schulte. "The Hydraulic Architecture of Conifers." In Functional and Ecological Xylem Anatomy, 39–75. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15783-2_2.
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Hacke, Uwe G. "The Hydraulic Architecture of Populus." In Functional and Ecological Xylem Anatomy, 103–31. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15783-2_4.
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Tyree, Melvin T., and M. H. Zimmermann. "Hydraulic Architecture of Woody Shoots." In Xylem Structure and the Ascent of Sap, 143–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04931-0_5.
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Steudle, Ernst. "Hydraulic Architecture of Vascular Plants." In Plant Desiccation Tolerance, 185–207. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_10.
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Tyree, Melvin T., and Frank W. Ewers. "Hydraulic Architecture of Woody Tropical Plants." In Tropical Forest Plant Ecophysiology, 217–43. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-1163-8_8.
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Tyree, Melvin T., and M. H. Zimmermann. "Hydraulic Architecture of Whole Plants and Plant Performance." In Xylem Structure and the Ascent of Sap, 175–214. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04931-0_6.
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Bizzarri, Claudio, and David Soren. "Etruscan Domestic Architecture, Hydraulic Engineering, and Water Management Technologies." In A Companion to the Etruscans, 129–45. Hoboken, NJ: John Wiley & Sons, Inc, 2015. http://dx.doi.org/10.1002/9781118354933.ch10.
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Zhong, Feifeng. "Sustainable transformation design of Lingnan vernacular architecture and landscape." In Frontiers in Civil and Hydraulic Engineering, Volume 1, 524–32. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003344209-70.
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Zhang, Xiaosong, and Mingyu Jin. "Research on the application of “Dracaena-Fractal” in architecture." In Frontiers in Civil and Hydraulic Engineering, Volume 1, 616–24. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003344209-81.
Full textConference papers on the topic "Hydraulic architecture"
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Martin, J. Michael, and Mark E. Everett. "Hydraulic architecture of alluvial floodplains." In Symposium on the Application of Geophysics to Engineering and Environmental Problems 2021. Society of Exploration Geophysicists and Environment and Engineering Geophysical Society, 2021. http://dx.doi.org/10.4133/sageep.33-100.
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Zolfaghari Sharak, Ashkan, Ebrahim Ghanbari, Hassan Dehghanpour, and Doug Bearinger. "Fracture Architecture from Flowback Signature: A Model for Salt Concentration Transient." In SPE Hydraulic Fracturing Technology Conference. Society of Petroleum Engineers, 2014. http://dx.doi.org/10.2118/168598-ms.
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Holcomb, William, Randy F. LaFollette, and Ming Zhong. "The Third Dimension: Productivity Effects From Spatial Placement and Well Architecture in Eagle Ford Shale Horizontal Wells." In SPE Hydraulic Fracturing Technology Conference. SPE, 2015. http://dx.doi.org/10.2118/spe-173343-ms.
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Abstract Eagle Ford shale formation exhibits highly variability hydrocarbon production rates and EUR within small areas, indicating a highly heterogeneous reservoir. Attempts to determine performance drivers among geological, production or completion data points have produced inconclusive results. For example, production for one cluster of nearby wells may be strongly correlated with proppant quantity, while the trend is not valid for a group of similar wells a short distance away. A more widely valid set of correlations could improve engineering efficiency and productivity across the play. Multivariate statistical modeling has indicated that wellbore architecture factors influence well performance. Such models have determined relative influence of such factors as fracturing fluid type and volumes, proppant sizes and volumes, etc. On the wellbore architecture side, prior studies found that surface latitude and longitude are among the strongest drivers. However, these studies largely omitted consideration of the third dimension (relative vertical location in the reservoir). This study evaluates productivity influences from azimuth, dip, porpoising, and TVD from heel to toe (vertical zone coverage). It also reconsiders previously studied factors (such as fracturing fluids and proppants) with a considerably larger body of data—especially longer-term production data—than was available for the prior studies. The goal is to determine geological, wellbore architecture, and completion factors that show statistical significance as performance drivers, and where they are applicable if the results vary across the play.
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Danaee, Siavash, Jarmo Nurmi, Tatiana Minav, Jouni Mattila, and Matti Pietola. "Direct Position Control of Electro-Hydraulic Excavator." In BATH/ASME 2018 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fpmc2018-8896.
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Position measurement in the electro-hydraulic systems is feasible via the utilization of physical sensors. An improvement in technology has led to the manufacturing of high accurate position sensors for direct position control. This paper proposes utilization of direct position control in an electro-hydraulic system with a new hydraulic zonal system architecture implemented with Direct Driven Hydraulics. It was mentioned in early study that this hydraulic system architecture as a replacement for the traditional valve-based hydraulic systems, has higher energy efficiency rate. In this study, the simulation implementation and experimental verification of Direct Driven Hydraulics (DDH) will be investigated for a micro excavator test case from position control point of view. Results demonstrated that the implementation of DDH in an excavator case will lead to maximum 5 cm error in a single-cycle movement.
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Huang, Xiong, and Min Wan. "Research on Landscape Architecture in Hydraulic Engineering." In International Conference On Civil Engineering And Urban Planning 2012. Reston, VA: American Society of Civil Engineers, 2012. http://dx.doi.org/10.1061/9780784412435.092.
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Holcomb, William David, Randy F. Lafollette, and Ming Zhong. "The Third Dimension: Productivity Effects From Spatial Placement and Well Architecture in Eagle Ford Shale Horizontal Wells." In SPE Hydraulic Fracturing Technology Conference. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/173343-ms.
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Li, Perry Y., Jacob Siefert, and David Bigelow. "A Hybrid Hydraulic-Electric Architecture (HHEA) for High Power Off-Road Mobile Machines." In ASME/BATH 2019 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/fpmc2019-1628.
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Abstract Traditionally, off-road mobile machines such as excavators and wheel loaders are primarily powered by hydraulics and throttling valves are used to control their work circuits. In recent years, two general trends are towards more energy efficient systems and electrification. With electrification, both efficiency and control performance can be improved by the elimination of throttling losses and the use of high-bandwidth inverter control. Electrification is generally accomplished with Electro-hydraulic actuators (EHA) but they are limited to lower powered systems due to the high cost of electric machines capable of high power or high torque. This paper presents preliminary results of a new system architecture for off-road vehicles to improve efficiency and control performance. The architecture combines hydraulic power and electric power in such a way that the majority of power is provided hydraulically while electric drives are used to modulate this power. The hybrid hydraulic-electric architecture (HHEA) and its rationale are described. In addition, a case study is presented to illustrate its operation, its potential for energy saving, and its benefits of component downsizing. The case study indicates that compared to a baseline load sensing system, the HHEA has the potential to reduce energy consumption by more than 50%. Furthermore, the torque capability of the electrical components need only be ∼ 28% of what is required for the direct application of EHA.
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Ketelsen, Søren, Torben Ole Andersen, Morten Kjeld Ebbesen, and Lasse Schmidt. "Mass Estimation of Self-Contained Linear Electro-Hydraulic Actuators and Evaluation of the Influence on Payload Capacity of a Knuckle Boom Crane." In ASME/BATH 2019 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/fpmc2019-1689.
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Abstract Self-contained linear hydraulic drives are characterized by having integrated the hydraulic power unit e.g. electrical prime mover, hydraulic pumps etc. and the hydraulic cylinder in a single compact unit. Compared to the hydraulic cylinder itself, the mass of the self-contained linear actuator is significantly larger. For some applications, e.g. crane manipulators the additional mass of the actuators compared to conventional valve-controlled hydraulics, may reduce the payload capacity, which is a central performance parameter. As a case study, a medium sized two link knuckle boom crane is modelled and by assuming the force capability of the hydraulic cylinders to be the limiting factor, the reduction in payload capacity is examined if replacing the knuckle boom cylinder with a self-contained hydraulic cylinder drive. By focusing on seven different hydraulic circuit architectures, this study estimates the mass of compact pump-controlled actuators and investigates to what extent the choice of system topology affects the mass of the actuator, and thus payload capacity of the crane. The results show that the choice of hydraulic circuit architecture may affect both the required amount of installed power and the mass of the self-contained actuator. For the considered knuckle boom crane the estimated mass of the needed 59 kW self-contained actuator ranges from 2300 kg to 2521 kg depending on the hydraulic circuit architecture. The mass of the hydraulic cylinder itself used for conventional valve actuation is estimated to 1674 kg. If the entire working range is considered, installing the heavier self-contained actuator reduces the payload capacity with up to 3 % compared to conventional valve actuation.
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Pena, Oscar, and Michael J. Leamy. "A Self-Contained Architecture for Energy Recovery in Hydraulic Elevators." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37696.
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This paper presents a novel energy storage and recovery architecture for speed-controlled hydraulic actuation in hydraulic elevators. The study is motivated by a need to increase efficiency in the fluid power industry, in general, and hydraulic elevators, in particular. In contrast to previously employed systems, the proposed architecture eliminates the need for throttling and inefficient energy conversions in electric motor/generators. The system has 6 main components: 1 actuator, 1 hydraulic transformer composed of 2 pump/motors, 2 accumulators, a reservoir or small auxiliary accumulator, and a small auxiliary electric motor to recharge accumulators. By operating in 3 different modes, the system is always able to recapture energy when decreasing actuation speed, and return energy if needed when increasing actuation speed. Assessment of the proposed architecture is accomplished through high-fidelity simulations and a simplified analytical model. The analytical model is derived with the pump/motor displacements as a single input. A heuristic rule-based control is developed to control the high-fidelity simulation through an operation cycle and a comparison to a counterweighted elevator simulation is done to validate energy advantages of the novel system. Preliminary results demonstrate the ability of the system to follow a velocity profile using a single input. Comparison with a conventional counterweighted hydraulic elevator shows a large increase in energy efficiency. It is believed the architecture may have additional applicability to a wide range of hydraulic machines, such as heavy equipment used in construction, manufacturing, forestry, etc.
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Marani, Pietro, and Massimo Martelli. "Energy and Control Characteristics of a Novel Meter Out Hydraulic System for Mobile Applications." In ASME/BATH 2017 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fpmc2017-4269.
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The metering out sensing system represents the latest, and most promising, architectural concept for improving the performance of mobile multiple actuation systems through hydraulic proportional components control. The first part of the paper introduces the novel architecture of meter-out sensing control system, properly designed to distribute the flow rate directed to actuators according to the proportional control of the metering out element only. To do this, an innovative piloting subsystem controls the pump displacement, while a set of compensated proportional control valves applied to actuators outlet work to manage the load unbalance. The inlet doesn’t have any proportional throttle element thus reducing control losses with respect to state-of-the-art systems. In this way, the architecture is able to control both resisting and overrunning loads, and its design could easily include the automatic activation of the regenerative function to limit the requested hydraulic power. Then, the paper highlights how the proposed architecture of meter-out sensing system, which does not require complex sensor networks or complex electronic controls, could overcome the most important limitations affecting other control technologies currently adopted in mobile hydraulics. The third part of the paper depicts the main results obtained in the evaluation of the performance figures of merit for the metering out sensing system, performed through a Virtual Test Procedure applied to a lumped and distributed parameter numerical model.
Reports on the topic "Hydraulic architecture"
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Li, Perry. Hybrid Hydraulic-Electric Architecture (HHEA) for Mobile Machines (Final Report). Office of Scientific and Technical Information (OSTI), July 2022. http://dx.doi.org/10.2172/1878730.
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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.