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Статті в журналах з теми "5 axes":
1
SATO, Ryuta, Yuya YOKOBORI, and Masaomi TSUTSUMI. "Dynamic Synchronous Accuracy of Translational Axes and Rotational Axes in 5-axis Machining Center." Journal of the Japan Society for Precision Engineering, Contributed Papers 72, no. 1 (2006): 73–78. http://dx.doi.org/10.2493/jspe.72.73.
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USHIKU, Kentaro, Masaomi TSUTSUMI, and Akinori SAITO. "Calibration of rotary axes of 5-axis machining centers." Proceedings of The Manufacturing & Machine Tool Conference 2002.4 (2002): 181–82. http://dx.doi.org/10.1299/jsmemmt.2002.4.181.
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Sato, Ryuta, and Masaomi Tsutsumi. "High Performance Motion Control of Rotary Table for 5-Axis Machining Centers." International Journal of Automation Technology 1, no. 2 (November 5, 2007): 113–19. http://dx.doi.org/10.20965/ijat.2007.p0113.
Анотація:
We discuss motion control techniques of rotary tables for 5-axis machining centers. Three translational axes and two rotary ones are controlled simultaneously in the machining of complex shapes such as impellers. A tilting rotary table powered by a worm gear is generally used as the rotary axes for 5-axis machining centers, and various causes of inaccuracy exist in the rotary axes. In this study, we clarified three causes of inaccuracy exists in the rotary axis: rotational fluctuation in the worm gear, backlash, and measurement delay of rotary encoder for feedback. Motor torque saturation of the rotary axis also causes a problem when rotational velocity is changed rapidly. Based upon investigated results, we propose compensators for improving synchronous accuracy. We avoid torque saturation in the rotary axis through acceleration-deceleration design. To verify the effectiveness of the proposed compensators, we applied them to an experimental set-up including a rotary axis. As the results of experiments, it is clarified that the proposed compensators improve the synchronous accuracy of translational and rotary axes.
4
Gebhardt, Michael, Alexander Schneeberger, Sascha Weikert, Wolfgang Knapp, and Konrad Wegener. "Thermally Caused Location Errors of Rotary Axes of 5-Axis Machine Tools." International Journal of Automation Technology 8, no. 4 (July 5, 2014): 511–22. http://dx.doi.org/10.20965/ijat.2014.p0511.
Анотація:
This paper presents the results of detailed thermal analysis of a 5-axis machine tool with focus on the rotary axes. The rotary axes are characterized regarding their position and orientation errors as a function of the underlying thermal load, contributing significantly to the overall accuracy. A physical model is presented, which allows the simulation of the thermal behavior of the rotary axes based on the power input to the drives of the rotary axes and the heat conduction in a swiveling rotary table unit and convection into environment. This enables an external online-compensation of thermal errors. The compensation model is verified and validated.
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Florussen, Guido, Koen Houben, Henny Spaan, and Theresa Spaan-Burke. "Automating Accuracy Evaluation of 5-Axis Machine Tools." International Journal of Automation Technology 14, no. 3 (May 5, 2020): 409–16. http://dx.doi.org/10.20965/ijat.2020.p0409.
Анотація:
A wireless non-contact 3D measuring head is used to determine the accuracy of 5-axis machine tools. The measuring head is inserted in the spindle by the tool exchanger automating the measurement routine used. For checking the linear machine axes, a cross shaped artefact containing 13 precision balls is introduced, named Position Inspector, enabling the determination of positioning and straightness errors of two linear axes in one setup. The squareness error between both axes is also determined in this setup. This artefact can be mounted on a pallet system for automatic loading and is measured in a bi-directional run. This artefact can be measured in different orientations (i.e., horizontal, inclined, vertical) and is pre-calibrated with a CMM. The measurement sequence using this artefact is executed in eight minutes and its design and support system is addressed in this paper. The location errors and orientation errors of the axis average line (or pivot line) of both rotary axes are determined with the Rotary Inspector using the same measuring head with a single precision ball. For this, kinematic tests are used from ISO10791-6, e.g., the BK1 test, BK2 test which apply for trunnion or swivel table machines. Derived parameters can be used for machine correction resulting in a significantly improved machine accuracy. An example is given where this correction is performed automatically by implementing this measurement system in the machine’s controller. Finally the machine tool is tested using the BK4 test. For this test all 5-axes are moved simultaneously and the measured displacements between the machine’s spindle and table in X-, Y-, and Z-directions are compared to tolerance levels. This final test reveals the machine’s overall accuracy and dynamic behavior.
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Sellmann, Florian, Titus Haas, Hop Nguyen, Sascha Weikert, and Konrad Wegener. "Orientation Smoothing for 5-Axis Machining Using Quasi-Redundant Degrees of Freedom." International Journal of Automation Technology 10, no. 2 (March 4, 2016): 262–71. http://dx.doi.org/10.20965/ijat.2016.p0262.
Анотація:
A new approach for set point generation in the field of 5-axis machining using quasi-redundant degrees of freedom is introduced in this study. In machine tools that possess both rotational and translational axes, no bijective correlation exists between the tool center point and the movement of the machine tool axes based on the manufacturing tolerances. Depending on the manufacturing process, as many as two additional degrees of freedom exist that allow the machine tool axes movement to be optimised within the given manufacturing tolerances with respect to the axes’ inertia. In this study to reduce the mechanical excitation of the machine tool, the jerk of the machine tool axes is minimised. To enhance robustness, the optimisation problem is formulated as a quadratic program with linear constraints. This problem can be solved by using an interior point method. An application example shows that when exploiting quasi-redundancy, the mechanical excitation of the machine tool can be reduced.
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Cuccolini, G., L. Orazi, and A. Fortunato. "5 Axes computer aided laser milling." Optics and Lasers in Engineering 51, no. 6 (June 2013): 749–60. http://dx.doi.org/10.1016/j.optlaseng.2013.01.015.
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Breaz, Radu-Eugen, Sever-Gabriel Racz, and Octavian-Constantin Bologa. "5-axes modular CNC machining center." MATEC Web of Conferences 112 (2017): 06004. http://dx.doi.org/10.1051/matecconf/201711206004.
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Briand, Christopher H., Usher Posluszny, and Douglas W. Larson. "Differential axis architecture in Thuja occidentalis (eastern white cedar)." Canadian Journal of Botany 70, no. 2 (February 1, 1992): 340–48. http://dx.doi.org/10.1139/b92-045.
Анотація:
Quantitative architectural variation was investigated among the axes of Thuja occidentalis. Forty axes of each axis order were randomly sampled and for each axis: length, excurrency index, basal diameter, number of daughter axes, number of basal reiterated axes, dorsiventrality index, and percentage of length partitioned into photosynthetic (bearing green leaves) and nonphotosynthetic (nongreen) components was determined. The crown exhibited six axis orders. Both axis length and basal diameter declined with increasing axis order, and crown form was excurrent. The number of daughter axes was highest on axis order 1 (trunk) and lowest on axis order 5. Axis orders 2 through 4 had a similar number of daughter axes. The frame of the tree was composed of axis orders 1 and 2. These axes were radially symmetrical in midpoint cross section, exhibited indeterminate growth, and only a small percentage of their length was devoted to photosynthetic tissue. Axis orders 3 through 6, taken together, had many characteristics of compound leaves. They were dorsiventrally flattened, exhibited determinate growth (axis terminated by a cone or abscised), and the majority of their length was devoted to photosynthetic tissue. In autumn these axes were often abscised as a unit. Both male and female cones were located terminally on axis orders through 6, with 82.7% of male cones occurring on axis order 6, and 86.0% of female cones occurring on axis order 5. The architectural unit of T. occidentalis resembled that of Thuja plicata. Attims' model most closely resembles the architectural pattern of these two species. Key words: Thuja occidentalis, eastern white cedar, architecture.
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SATO, Ryuta, Yuya YOKOBORI, and Masaomi TSUTSUMI. "Synchronous Accuracy of Translational and Rotary Axes in 5-axis Machining Centers(Precision positioning and control technology)." Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2005.3 (2005): 993–98. http://dx.doi.org/10.1299/jsmelem.2005.3.993.
Дисертації з теми "5 axes":
1
Jiang, Xiaogeng. "Characterising geometric errors in rotary axes of 5-axis machine tools." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5871/.
Анотація:
It is critical to ensure that a 5-axis machine tool is operating within its geometric tolerance. However, there are various sources of errors influencing its accuracy; testing them with current methods requires expensive equipment and long machine down time. This motivates the development of a simple and fast way to identify and characterise geometric errors of 5-axis machine tools. A method using a Double Ball Bar (DBB) is proposed to characterise rotary axes Position Independent Geometric Errors (PIGEs), which are caused by imperfections during assembly of machine components. An established method is used to test the same PIGEs, and the results are used to validate the developed method. The Homogeneous Transformation Matrices (HTMs) are used to build up a machine tool model and generate DBB error plots due to different PIGEs based on the given testing scheme. The simulated DBB trace patterns can be used to evaluate individual error impacts for known faults and diagnose machine tool conditions. The main contribution is the development of the fast and simple characterisation of the PIGEs of rotary axes. The results show the effectiveness and improved efficiency of the new methods, which can be considered for 5-axis machine tool maintenance and checking.
2
Lacharnay, Virgile. "Modélisation mécanique intégrant des champs répulsifs pour la génération de trajectoires 5 axes hors collision." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0042/document.
Анотація:
Le processus de réalisation des pièces de formes complexes par usinage est un processus essentiel dans les domaines de l'aéronautique, de l'automobile, des moules et des matrices. Alors que l'usinage 5 axes grande vitesse est maintenant répandu dans les grands groupes industriels, il reste plusieurs problématiques à traiter. L'évitement de collisions le long de la trajectoire outil programmée en alors traité, notamment au niveau des interférences globales représentant une collision entre l'outil et son environnement. Classiquement, l'évitement de collisions dans le domaine de l'usinage 5 axes grande vitesse peut être programmé à l'aide d'une analyse géométrique de la situation. Si une collision est détecté, alors une phase de correction et d'optimisation peuvent être utilisée afin d'obtenir une nouvelle trajectoire hors collision. Le but des travaux est alors d'utiliser une modélisation physique afin d'obtenir une trajectoire corrigée hors collision le plus lisse possible. Pour ce faire le mouvement de l'outil est alors étudié d'un point de vue dynamique afin d'éviter les réorientation brutal post correction. De plus, les éléments constituants les obstacles émettent une action répulsive à distance. Cela permet, au cours de la programmation, d'anticiper l'approche d'un obstacle et ainsi d'entamer les corrections d'orientation outil en prévision d'une possible collision. Cette démarche de modélisation du mouvement étudiée permet alors de réaliser des simulations sur des pièces classiquement usinées dans les domaines énoncés précédemment. Dans le but de généraliser la programmation réalisée, il est alors important de comprendre comment les éléments obstacles sont représentés ainsi que la modélisation retenu pour l'outil utilisé au cours de la simulation. Enfin, la résolution de la dernière problématique mise en avant au cours de cette thèse concerne les temps de calcul obtenus. Il a été montré, après de multiples simulations, que ces derniers peuvent exploser d'un point de vue combinatoire pour des utilisateurs exigeants (modélisation fine de l'outil et de l'environnement). Une méthode de pré calcul est alors présentée utilisant la voxelisation permettant de diminuer les temps de calcul de manière très importante sans pour autant perdre de manière importante sur la solution obtenue. Le dernier objectif présenté est de proposer une approximation permettant de diminuer nettement les temps de calcul tout en conservant une assurance de non-collision. Cette méthode notée voxelisation consiste en utilisant une interpolation à diminuer le temps de calcul. L’important est alors de comprendre quels inconvénients se rattachent à la voxelisation et à partir de quand cette dernière apporte un résultat acceptableAlthough 5-axis free form surfaces machining is commonly proposed in CAD/CAM software, several issues still need to be addressed and especially collision avoidance between the tool and the part. Indeed, advanced user skills are often required to define smooth tool axis orientations along the tool path in high speed machining. In the literature, the problem of collision avoidance is mainly treated as an iterative process based on local and geometrical collision tests. In this paper, an innovative method based on potential fields is used to generate 5-axis collision-free smooth tool paths. In the proposed approach, The ball-end tool is considered as a rigid body moving in 3D space on which repulsive force, deriving from a scalar potential field attached to the check surfaces, and attractive forces are acting. The resolution of the differential equations of the tool motion ensure smooth variations of the tool axis orientation. The proposed algorithm is applied on open pocket parts such as an impeller and a pocket corner to emphasize the effectiveness of this method to avoid collision. After that, it is possible to see that de calculation time can be very importante for a delicate mesh. It is for that, a voxelisation method is developed to decrease these
3
Ancuta, Andreea Elena. "Machines parallèles 5-axes pour l'usinage aéronautique de pièces minces." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20051.
Анотація:
Actuellement, certaines pièces aéronautiques sont usinées par des procédés chimiques efficaces, mais mettant en jeu des produits polluants et dangereux pour les ouvriers qui travaillent à leur contact. Par conséquent, il est impératif de trouver une solution qui serait au minimum aussi compétitive que l'usinage chimique et beaucoup moins risquée pour l'homme et l'environnement. Dans cette optique, l'usinage à grande vitesse (UGV) constitue une alternative sérieuse et efficace. Depuis des années, les machines-outils à structure parallèle ont fait leur preuve dans l'UGV. C'est donc dans ce contexte d'usinage des pièces aéronautiques de grandes longueurs et de formes complexes que de nouvelles architectures parallèles sont proposées. Dans ce manuscrit, d'après les contraintes de la tâche, nous sélectionnons une large famille de cinématiques parallèles que nous modelions de manières générique et complète. Nous utilisons cette modélisation pour différentes propositions de mécanismes : 4 degrés de liberté avec plateforme mobile articulée, 4 degrés de liberté avec plateforme rigide et 5 degrés de liberté avec redondance et plateforme articulée. Ces travaux ont conduit à la réalisation d'un prototype qui a validé le concept d'une de ces machinesCurrently, some aeronautical parts are milled by efficient chemical processes, but involving products pollutants and hazardous for workers working on their contact. Therefore, it is imperative to find a solution that would be at least as efficient as chemical milling and much less risky for humans and the environment. It is recognized in the literature that high-speed milling is a serious and effective alternative for the above mentioned problems. Moreover, for years, machine tools based on parallel structure have proven their utility in high-speed milling. In the context of milling of lengthy and complex shaped aeronautical parts, new parallel architectures are proposed. In this manuscript, according to the constraints of tasks, we select a large family of parallel kinematic mechanism that we modelize in a generic and complete way. We use these models for different propositions of mechanisms: 4 degrees of freedom with articulated platform, 4 degrees of freedom with rigid platform and 5 degrees of freedom with actuation redundancy and articulated platform. This work leads to the realization of a prototype that validates the concept of one of these machines
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Grandguillaume, Laureen. "Execution adaptative de trajectoire 5 axes sur structures poly-articulées." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN059/document.
Анотація:
L’usinage 5 axes à grande vitesse est de plus en plus utilisé dans l’industrie pour réaliser des pièces de géométrie complexe à forte valeur ajoutée avec pour contrainte de respecter la qualité géométrique tout en maximisant la productivité. Dans ce contexte, la FAO et plus particulièrement la génération des trajectoires d’usinage jouent un rôle prépondérant. Ces travaux proposent de définir des trajectoires en fonction de la pièce à réaliser mais aussi de la structure poly articulée et de ses performances cinématiques. La grande diversité des structures en termes d’architecture et de cinématique impose une méthode de calcul générique facilitant la définition de trajectoires adaptées pour leur suivi. L’état de l’art des travaux réalisé dans les domaines de l’usinage et de la robotique pour répondre à cette problématique conduit à utiliser des polytopes de manipulabilité cinématique pour modéliser les contraintes cinématiques. L’analyse de ces polytopes et de la géométrie de la pièce à usiner permet de générer des trajectoires avec une vitesse outil/pièce maîtrisée et un temps de parcours réduit dans le cas de l’usinage 5 axes positionné et de l’usinage 5 axes continu. Ce formalisme met en avant les fortes dépendances entre les différents paramètres de la stratégie d’usinage (positionnement de la pièce, direction d’avance et orientation de l’outil) et permet de privilégier certaines combinaisons de ces paramètres pour maîtriser la vitesse d’exécution de la trajectoire5 axes high speed milling is increasingly used for manufacturing high addedvalue parts with complex forms in order to respect surface quality while maximizing productivity. In this context, CAM and more specifically toolpath computations play a major part. This work proposes to define toolpath depending on the workpiece but also onkinematical capacities of the polyarticulated structure.The large variety of structure in terms of architecture and kinematic enforce a generic calculation method to simplify adaptative toolpath generation. A state of the art realized in machining and robotics proposes to investigate the use of kinematical manipulability polytopes to represent kinematical capacities. An analysis of the polytopes and of the workpiece allows to generate toolpaths with a controlled feedrate and a decreasing time in 5 axes positionned milling and in 5 axes continous milling. This formalism highlights strong interactions between milling strategy parameters (workpiece setup, feed direction, tool orientation) and allows to prioritize specific parameters mix to have a controlled execution feedrate
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Jousselin, Baptiste. "Développement d'une méthodologie de génération de trajectoires d'ébauche en usinage 5 axes." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST061.
Анотація:
La complexité des pièces à fabriquer ne permet plus de s’affranchir d’aides numériques à la programmation de trajectoires d’usinage telles que les logiciels de Fabrication Assistée par Ordinateur (FAO). Cependant, la large gamme d’opérations pour la finition 5 axes généralement proposée par les logiciels contraste avec le manque de solutions concernant la phase d’ébauche. Cette séquence peut pourtant améliorer la productivité du processus d’usinage global.Les travaux présentés dans cette thèse portent donc sur le développement d’une méthodologie de génération de trajectoires d’usinage 5 axes simultanés pour la séquence d’ébauche. L’utilisation de courbes pour guider l’outil dans le volume de matière à retirer garantit le parcours de la totalité de celui-ci, et donc un enlèvement de matière maximal. Les courbes guides sont construites automatiquement à partir du modèle numérique de la pièce à usiner et mettent en œuvre des algorithmes de calcul d’offsets de courbes et de surfaces au moyen de méthodes vectorielles ou de champs scalaires. Les orientations de l’outil de long des courbes guides sont ensuite déterminées par un algorithme d’Optimisation Quadratique Successive, selon des critères de productivité, de comportement de l’outil, et de qualité de surface, par la recherche d’un paramétrage spécifique des courbes guides.L'implémentation de la stratégie d'ébauche 5 axes dans le logiciel de FAO TopSolid a permis de réaliser des essais d’usinage avec outils toriques et valider la stratégie sur des pièces industrielles typiques de l’industrie aéronautiqueThe complexity of the parts to be manufactured leads to an indispensable recourse to digital media for trajectory planning such as Computer Aided Manufacturing (CAM) software. However, a real imbalance is noted between the wide range of 5-axis finishing operations currently available in CAM software and the lack of solutions for the roughing sequence, which can though improve the productivity of the overall machining process.This thesis manuscript therefore tackles the development of a simultaneous 5-axis toolpath planning methodology for the roughing sequence. Guiding curves are used to create a geometric path which allows the tool to travel the whole volume to remove, and thus ensure a maximum material removal. Guiding curves are built automatically from the numerical model of the workpiece and implemented algorithms for calculating curve and surface offsets using vector methods or scalar fields. The orientations of the tool along the guiding curves are then determined by a Sequential Quadratic Programming algorithm, according to criteria of productivity, tool behaviour, and surface quality, by searching for a specific parameterization of the guiding curves.The implementation of the 5-axis roughing strategy in the TopSolid CAM software enabled machining tests with toroidal cutter, which allowed the strategy's validation on typical parts of the aerospace industry
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Castagnetti, Cedric. "Amélioration du comportement cinématique des machines par l'optimisation des trajets d'usinage 5 axes." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00731128.
Анотація:
Le couplage précision-vitesse est une problématique importante de l'usinage à 5 axes. Le respect de la précision impose à la machine de ralentir. De plus, le calcul du trajet ne prend pas en compte le comportement de la machine et induit aussi des ralentissements. Ces travaux de thèse visent deux objectifs : Optimiser le comportement de la machine outil en modifiant l'orientation de l'axe outil dans le repère machine ; Garantir le respect des contraintes géométriques fonctionnelles sur l'orientation de l'axe outil. Une méthode d'optimisation sous contrainte est proposée. La fonction objectif utilise un modèle simplifié du comportement de la machine. Le concept du Domaine d'Orientation Admissible est alors défini pour contraindre l'orientation de l'outil dans le repère pièce puis dans le repère machine afin d'y réaliser l'optimisation. La méthode d'optimisation est comparée à des méthodes alternatives selon des critères de rapidité de calcul et de performance.
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Anthony, Guiot. "Modélisation et simulation du procédé de prépolissage automatique sur centre d'usinage 5 axes." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00816769.
Анотація:
La réalisation de formes complexes comme les moules ou les prothèses médicales nécessite l'utilisation d'opérations de super finition pour obtenir de faibles défauts géométriques, pouvant aller jusqu'au poli-miroir. Ces opérations de prépolissage et de polissage sont encore régulièrement réalisées manuellement. En effet, malgré des avantages en termes de répétabilité, de productivité et de qualité géométrique, les méthodes de polissage automatique sont peu utilisées, car elles nécessitent une mise au point importante. Les travaux de recherche présentés dans ce mémoire participent à la maîtrise du procédé de polissage automatique tout en contrôlant la qualité géométrique des pièces. Pour parvenir à cette maîtrise, un outil de simulation de l'enlèvement de matière est mis en place. Cet outil permet de simuler l'enlèvement de matière au cours d'une opération de prépolissage réalisée sur centre d'usinage 5 axes. Il se base sur un modèle du contact obtenu entre l'outil de pré-polissage et la pièce, ainsi que sur un modèle du pouvoir abrasif intégrant l'usure et l'encrassement du disque. Cette simulation permet de vérifier la régularité de l'abrasion sur une surface et d'identifier les zones pouvant faire apparaitre des défauts macro-géométriques importants. Une méthode est également proposée pour compenser les variations du pouvoir abrasif au cours du temps. La compensation s'effectue en optimisant les consignes de vitesse d'avance et/ou de fréquence de broche le long de la trajectoire. Cette méthode de pilotage permet d'obtenir un taux d'enlèvement de matière plus constant et ainsi de réduire les défauts géométriques générés pendant une opération de prépolissage.
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Guiot, Anthony. "Modélisation et simulation du procédé de prépolissage automatique sur centre d'usinage 5 axes." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-01044984.
Анотація:
La réalisation de formes complexes comme les moules ou les prothèses médicales nécessite l'utilisation d'opérations de super finition pour obtenir de faibles défauts géométriques, pouvant aller jusqu'au poli-miroir. Ces opérations de pré-polissage et de polissage sont encore régulièrement réalisées manuellement. En effet, malgré des avantages en termes de répétabilité, de productivité et de qualité géométrique, les méthodes de polissage automatique sont peu utilisées car elles nécessitent une mise au point importante. Les travaux de recherche présentés participent à la maîtrise du procédé de polissage automatique tout en contrôlant la qualité géométrique des pièces. Pour parvenir à cette maîtrise, un outil de simulation de l'enlèvement de matière est mis en place. Cet outil permet de simuler l'enlèvement de matière au cours d'une opération de prépolissage réalisée sur centre d'usinage 5 axes. Il se base sur un modèle du contact obtenu entre l'outil de pré-polissage et la pièce, ainsi que sur un modèle du pouvoir abrasif intégrant l'usure et l'encrassement du disque. Cette simulation permet de vérifier la régularité de l'abrasion sur une surface et d'identifier les zones pouvant faire apparaitre des défauts macro-géométriques importants. Une méthode est également proposée pour compenser les variations du pouvoir abrasif au cours du temps. La compensation s'effectue en optimisant les consignes de vitesse d'avance et/ou de fréquence de broche le long de la trajectoire. Cette méthode de pilotage permet d'obtenir un taux d'enlèvement de matière plus constant et ainsi de réduire les défauts géométriques générés pendant une opération de prépolissage.
9
Castagnetti, Cédric. "Amélioration du comportement cinématique des machines par l'optimisation des trajets d'usinage 5 axes." Clermont-Ferrand 2, 2008. http://www.theses.fr/2008CLF21878.
Анотація:
Le couplage précision-vitesse est une problématique importante de l'usinage à 5 axes. Le respect de la précision impose à la machine de ralentir. De plus, le calcul du trajet ne prend pas en compte le comportement de la machine et induit aussi des ralentissements. Ces travaux de thèse visent deux objectifs : Optimiser le comportement de la machine outil en modifiant l'orientation de l'axe outil dans le repère machine ; Garantir le respect des contraintes géométriques fonctionnelles sur l'orientation de l'axe outil. Une méthode d'optimisation sous contrainte est proposée. La fonction objectif utilise un modèle simplifié du comportement de la machine. Le concept du Domaine d'Orientation Admissible est alors défini pour contraindre l'orientation de l'outil dans le repère pièce puis dans le repère machine afin d'y réaliser l'optimisation. La méthode d'optimisation est comparée à des méthodes alternatives selon des critères de rapidité de calcul et de performance
10
Breteau, Thomas. "USINAGE 5 AXES DE SURFACES GAUCHES CARACTÉRISÉES PAR UN CRITÈRE D'ÉTAT DE SURFACE ADAPTATIF." Phd thesis, Ecole centrale de nantes - ECN, 2010. http://tel.archives-ouvertes.fr/tel-00560042.
Анотація:
Ce travail, réalisé dans le cadre d'une thèse Allocation Couplée et un contexte inter-laboratoires fort : IRCCyN – IRENav – IFMA offrant de multiples ressources en productique et en hydrodynamique, vise à améliorer le processus de réalisation des hélices marines. Certaines des spécifications géométriques établies durant la conception perdent définitivement, lors de l'étape de définition de la stratégie de fabrication en finition, leur caractère fonctionnel au travers de leur traduction en paramètres liés à la machine d'usinage. Cette étude vise à proposer une alternative au polissage en renforçant les liens fonctionnels entre les propriétés de l'hélice et les paramètres géométriques des opérations de fraisage. La première partie du travail est consacrée à l'étude du processus de conception et de réalisation ainsi qu'au cycle de vieillissement des hélices marines. Les trajectoires d'usinage sont généralement obtenues par post-traitement du modèle numérique créé en C.A.O. ; passer directement des lois hydrodynamiques au trajet outil permet de mieux répondre aux exigences fonctionnelles des propulseurs marins. Ainsi des critères multiphysiques doivent être à la source de la spécification de l'état de surface, du format d'interpolation support des trajectoires et, dans le cadre d'une approche générique du processus d'usinage, du choix de l'ensemble des intervenants du processus de réalisation des hélices. Dans un second temps les relations entre les différentes activités du processus de fabrication des hélices sont restructurées et de nouvelles liaisons sont proposées entre les domaines dits « fonctionnel », « virtuel » et « physique » pour prendre en compte des contraintes fonctionnelles et ainsi aboutir à la mise en place d'un nouveau concept de génération de trajectoires d'usinage. Les lignes de frottements, signature hydrodynamique de l'hélice, sont suggérées pour supporter les trajectoires d'usinage. La complexité de ces données d'une part et celle de la géométrie hélice d'autre part nécessitent le développement d'une nouvelle stratégie de génération de trajectoires d'usinage. Ainsi, basés sur le formalisme de Bézier, des algorithmes d'interpolation sont proposés pour aboutir à des trajectoires continues au bord d'attaque, contrainte fonctionnelle incontournable et, chose essentielle, exploitables en usinage. Le passage par le bord d'attaque, lieu où la cavitation ne doit pas apparaître sous peine de se propager à l'ensemble de la pale, est l'objet de toutes les attentions. Les contraintes fonctionnelles insuffisantes en cet endroit sont, dans le cadre d'une approche multimétier, suppléées par des contraintes géométriques et des contraintes liées à la cinématique du centre d'usinage. Le trajet outil étant déterminé, une analyse de sa pertinence hydrodynamique est menée ; un découpage de la pale en zones d'application pertinente de la méthode est défini. Suite à cela, un modèle d'hélice de patrouilleur P400 de la Marine nationale est retenu comme cas d'étude. A partir de celui-ci, une étude expérimentale en bassin est mise en place en vue d'analyser, par comparaison avec une pale d'hélice étalon polie miroir, les effets de stries d'usinage orientées sur le comportement du fluide au voisinage d'une pale usinée selon la stratégie développée. Un fluide différent de celui d'évolution et une caméra rapide sont utilisés pour observer les modifications de comportement du fluide dues à l'état de surface dirigé. Les résultats de la campagne d'essais, qui reposent sur les techniques de traitement d'images, sont détaillés et analysés pour conclure sur les apports de la méthode en terme de coût et de temps de fabrication.
Книги з теми "5 axes":
1
Soldani, Simonetta, ed. Enzo Collotti e l'Europa del Novecento. Florence: Firenze University Press, 2011. http://dx.doi.org/10.36253/978-88-6453-290-5.
Анотація:
Emerging from a convention in honour of Enzo Collotti, this book traces his interests and fields of study. These gravitate around the tragic experiences of the Second World War, always played out in a perspective where the horizon is a Europe centred on Germany and on the lacerations that rippled out from Germany itself to embrace the entire continent with the consolidation of Nazism as a totalitarian power grounded in an ideology that was intrinsically reactionary and violently racist. There are six axes of investigation, closely intermeshed, addressed in the various contributions: socialism between the two wars; the lacerations of Germany; the European manifestations of Fascism; the experience of the Shoah, the construction of a shared historic memory of the dramas of the twentieth century and the problems of the Italian "eastern border".
2
Apro, Karlo. Secrets of 5-axis machining. New York, NY: Industrial Press, 2008.
3
Himaruya, Hidekaz. Yidaili: Axis powers : Hetalia 5. Taibei Shi: Dong li chu ban she you xian gong si, 2014.
4
Sharp, Burt M., Toby K. Eisenstein, John J. Madden, and Herman Friedman, eds. The Brain Immune Axis and Substance Abuse. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1951-5.
5
Schmitz, Volker, ed. Axel Honneth and the Critical Theory of Recognition. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-91980-5.
6
Flude, Ray. The axis powers' lost opportunity: The failure to develop an air service between Europe and the Far East 1942-5. Leicester: De Montfort University, 2000.
7
Duggan, Gerry, David Baldeon, and John Timms. Nova Volume 5: Axis. imusti, 2015.
8
Hidekaz, Himaruya. Hetalia Axis Powers Graphic Novel 5. Right Stuf Inc., 2013.
9
Larroca, Salvador, Rick Remender, and Daniel Acuna. Uncanny Avengers Volume 5: Axis Prelude. Panini UK Limited, 2015.
10
Larroca, Salvador, Rick Remender, Sanford Greene, Cullen Bunn, and Gabriel Hernandez Walta. Uncanny Avengers Volume 5: Axis Prelude TPB. Marvel Worldwide, Incorporated, 2015.
Частини книг з теми "5 axes":
1
Gasser, Lucy. "Shifting Axes." In East and South, 111–65. London: Routledge India, 2021. http://dx.doi.org/10.4324/9781003170556-5.
2
Jabran, Sohaib, Shajee Ahmed, Sarmad Afzal, and Faizan Tariq. "Axes CNC Milling Machine." In Functional Reverse Engineering of Strategic and Non-Strategic Machine Tools, 41–56. First edition. | Boca Raton : CRC Press, 2021. |: CRC Press, 2021. http://dx.doi.org/10.1201/9780367808235-5.
3
Kuijpers, Maikel H. G. "Metal axes and metallographic samples." In An Archaeology of Skill, 82–95. Oxon ; New York, NY : Routledge, 2017. | Series: Routledge studies in archaeology ; 29: Routledge, 2017. http://dx.doi.org/10.4324/9781315196022-5.
4
Pan, Fangyu, Yuewei Bai, Li Nie, Xiaogang Wang, Kai Liu, and Xiaoyan Wu. "The measurement for rotary axes of 5-axis machine tools." In Advances in Energy Science and Equipment Engineering II, 1277–82. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.1201/9781315116174-82.
5
Denkena, Berend, Jens Köhler, and Thomas Krawczyk. "Influence of 5-axes-kinematics Geometrical Accuracy in Riblet Manufacturing Processes." In Lecture Notes in Production Engineering, 69–74. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01964-2_10.
6
Wei, Juan, Jie Xiao, and Hong Wei Ma. "Development of a Control System on 5-Axes Automatic Scanning for Nondestructive Ultrasonic Test." In Materials Science Forum, 552–55. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-421-9.552.
7
Hu, S. J., W. J. Xiang, and Zhi Xiong Zhou. "Study on the 5-Axes NC Grinding Machine and Sharpening Technology for Ni Zhifu Drill Point." In Advances in Grinding and Abrasive Technology XIII, 460–64. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-986-5.460.
8
Leeming, David A. "Axis Mundi." In Encyclopedia of Psychology and Religion, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-27771-9_63-5.
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Lee, Loyd E. "The Axis new world order." In The War Years, 112–37. London: Routledge, 2021. http://dx.doi.org/10.4324/9781003206941-5.
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Williams, Alan, Vivian Cai, Michael Maestas, John Heit, and Stuart Taylor. "Multipoint Control for Single Axis Vibration Testing." In Special Topics in Structural Dynamics, Volume 5, 205–13. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75390-4_19.
Тези доповідей конференцій з теми "5 axes":
1
Hwang, J. D., H. C. Jung, K. B. Park, and Y. G. Jung. "A Study on the Development of a Practical Postprocessor for 5-Axis Machining." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-25190.
Анотація:
This paper deals with the development of a practical postprocessor for 5-axis machine tools. Recently, special 5-axis machine tools with non-orthogonal rotary axes as well as typical 5-axis machine tools with orthogonal rotary axes have been introduced. In the present work, the general equations of NC data for 5-axis configurations with non-orthogonal rotary axes are exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system suitable for all kinds of 5-axis machine tools not only with orthogonal rotary axes but also with non-orthogonal rotary axes, thereby expanding the range of application of the developed postprocessor. In addition, through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm was confirmed. Compatibility was improved by allowing exchange of data formats such as RTCP controlled NC data, Vector post NC data, and POF CL data, and convenience was increased by adding the function of work-piece origin offset. Consequently, a practical post-processor for 5-axis machining has been developed.
2
Chen, Hsin-Pao, Hsin-Hung Kuo, and Der-Min Tsay. "Removing Tool Marks for Impellers in Five-Axis Machining With Improved Interference-Free Tool Paths." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50205.
Анотація:
The paper deals with the procedure of removing a gouge phenomenon on impeller surfaces in 5-axis machining. That is, when an impeller of a centrifugal compressor is being cut, tool marks on its surfaces may exist in finish milling due to reverse movements of moving axes along a 5-axis interference-free tool path. For generating interference-free cutter location (CL) data needed in rough and semi-finish 5-axis cutting processes, first, a simple yet useful approach is proposed. To identify the potential gouge area and to solve the problem for a tool path having reverse motion directions with its moving axes in finish milling, the CL data are further smoothed to remove the reverse movements about its rotating and tilting axes. The effectiveness of this procedure has been experimentally confirmed by successful 5-axis finish milling of an impeller without leaving tool marks on its surfaces.
3
Lee, Yuan-Shin, and Tien-Chien Chang. "Automatic Planning for 5-Axis Sculptured Surface Machining." In ASME 1994 International Computers in Engineering Conference and Exhibition and the ASME 1994 8th Annual Database Symposium collocated with the ASME 1994 Design Technical Conferences. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/cie1994-0411.
Анотація:
Abstract In modern product design, sculptured surfaces are commonly used for functional and artistic shape design. Design of sculptured surfaces is evolutionary, consisting primarily of incremental changes to existing part surfaces. Manual operation planning for sculptured surface machining is known to be error-prone and inefficient, which requires considerable checking, verification, and rework. Five-axis machining has higher productivity and better machining quality than 3-axis machining. However, the programming for 5-axis machining is more difficult due to the complex simultaneous cutter movements along the machine’s five axes. This paper presents a systematic methodology to generate operation plans for 5-axis sculptured surface machining. A complete operation plan and the error-free cutter path can be automatically generated from the CAD part design. To achieve design for manufacturing of sculptured surface products, the machining unfeasibility information can be fed back to the designer for further design modification. Results of computer implementation and testing examples are also presented.
4
Shang peng, Xu anping, and Zhang dawei. "A DBB-based accuracy measurement method for rotary axes of high speed 5-axis CNC machining center." In 2010 International Conference on Mechanic Automation and Control Engineering (MACE). IEEE, 2010. http://dx.doi.org/10.1109/mace.2010.5536577.
5
Tang, Kai, Tony Woo, and Jacob Gan. "Maximum Intersection of Spherical Polygons and Workpiece Orientation for 4- and 5-Axis Machining." In ASME 1990 Design Technical Conferences. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/detc1990-0023.
Анотація:
Abstract Orienting the workpiece in such a way as to minimize the number of setups in a 4-axis or a 5-axis Numerical Control (NC) machine is formulated as follows: Given a set of spherical polygons (that are representations of curved surfaces visible to a 3-axis NC machine), find a great circle (the 4th axis) or a band (the 4th and the 5th axes) containing a great circle that intersects the polygons maximally. While there are potentially infinitely many solutions to this problem, a sphere is partitioned into O(N2) regions based on the N polygons. Within each of these regions, it is shown that it requires O(NlogN) time to determine maximum intersections and all the solutions are congruent. Central projection mapping is employed so as to present the algorithms in the plane.
6
Lin, Alan C., and Tzu-Kuan Lin. "A spherical two-circle approach to determining rotation angles for 5-axis NC machines with orthogonal rotation axes." In 2012 IEEE International Conference on Computer Science and Automation Engineering (CSAE). IEEE, 2012. http://dx.doi.org/10.1109/csae.2012.6273041.
7
Zhang, Dongsheng, Yundou Xu, Jiantao Yao, Yongsheng Zhao, and I.-Ming Chen. "Rotational axes and inverse kinematics analysis of a novel 5-DOF hybrid manipulator." In 2017 IEEE International Conference on Cybernetics and Intelligent Systems (CIS) and IEEE Conference on Robotics, Automation and Mechatronics (RAM). IEEE, 2017. http://dx.doi.org/10.1109/iccis.2017.8274800.
8
Parkin, Ian A. "Finding the Principal Axes of Screw Systems." In ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/dac-3731.
Анотація:
Abstract The paper provides computational methods for determining the principal screws of an N-system of screws of the form S^=∑i=1NaiS^i,aireal when a basis of N, 2 ≤ N ≤ 5, linearly independent screws Ŝi has been provided.
9
Guan, Li, and Xu-Xiang Zhang. "Parameters setting and verification of 5-axis machine with multiple axes rotary spindle head based on Master CAM X." In 2016 International Forum on Mechanical, Control and Automation (IFMCA 2016). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/ifmca-16.2017.120.
10
Kuz’mina, Ol’ga. "Metal axes of the bronze age abashevo culture." In Antiquities of East Europe, South Asia and South Siberia in the context of connections and interactions within the Eurasian cultural space (new data and concepts). Institute for the History of Material Culture Russian Academy of Sciences, 2019. http://dx.doi.org/10.31600/978-5-907053-35-9-222-225.
Звіти організацій з теми "5 axes":
1
ARMY WAR COLL CARLISLE BARRACKS PA. 5-Axis Machining Center for Small Components. Fort Belvoir, VA: Defense Technical Information Center, March 2007. http://dx.doi.org/10.21236/ada481292.
2
Waisel, Yoav, Bobbie McMichael, and Amram Eshel. Decision Making within Plant Root Systems. United States Department of Agriculture, March 1996. http://dx.doi.org/10.32747/1996.7613030.bard.
Анотація:
Architecture of a root system is the expression of the potential of various root types to branch, to grow and to coordinate with other plant organs, under the specific limitations of the environmental conditions. The present investigation has proven the following points. 1) Genotypes with different types of root systems were identified. The growth patterns of their roots and the distribution of laterals along their main axes were recorded. 2) The patterns of development of the root systems of four cotton genotypes, throughout the entire life cycle of the plants, were described, even at such a late stage of development when the total length of the roots exceeded two kilometers. To the best of our knowledge, this is the first time that an analysis of this type is accomplished. 3) The development of root systems under restrictive soil conditions were compared with those that have developed under the non-restrictive conditions of aeroponics. Results indicate that in the absence of the mechanical impedance of the soil, cotton plants develop single roots that reach the length of 6 m, and have a total root length of 2000 m. Thus, root growth is strongly inhibited by the soil, with some root types being inhibited more than others. 4) One of the important decisions, in constructing an operational root system architecture of mature plants, is the shift of the balance between various root fractions in favor of the very fine roots. 5) Root system architecture is determined, in part, by the sites of initiation of the lateral roots. This is determined genetically by the number of xylem archs and by the totuosity of the stele. Selection for such traits should be sought.
3
Funkenstein, Bruria, and Cunming Duan. GH-IGF Axis in Sparus aurata: Possible Applications to Genetic Selection. United States Department of Agriculture, November 2000. http://dx.doi.org/10.32747/2000.7580665.bard.
Анотація:
Many factors affect growth rate in fish: environmental, nutritional, genetics and endogenous (physiological) factors. Endogenous control of growth is very complex and many hormone systems are involved. Nevertheless, it is well accepted that growth hormone (GH) plays a major role in stimulating somatic growth. Although it is now clear that most, if not all, components of the GH-IGF axis exist in fish, we are still far from understanding how fish grow. In our project we used as the experimental system a marine fish, the gilthead sea bream (Sparus aurata), which inhabits lagoons along the Mediterranean and Atlantic coasts of Europe, and represents one of the most important fish species used in the mariculture industry in the Mediterranean region, including Israel. Production of Sparus is rapidly growing, however, in order for this production to stay competitive, the farming of this fish species has to intensify and become more efficient. One drawback, still, in Sparus extensive culture is that it grows relatively slow. In addition, it is now clear that growth and reproduction are physiological interrelated processes that affect each other. In particular sexual maturation (puberty) is known to be closely related to growth rate in fish as it is in mammals, indicating interactions between the somatotropic and gonadotropic axes. The goal of our project was to try to identify the rate-limiting components(s) in Sparus aurata GH-IGF system which might explain its slow growth by studying the ontogeny of growth-related genes: GH, GH receptor, IGF-I, IGF-II, IGF receptor, IGF-binding proteins (IGFBPs) and Pit-1 during early stages of development of Sparus aurata larvae from slow and fast growing lines. Our project was a continuation of a previous BARD project and could be divided into five major parts: i) obtaining additional tools to those obtained in the previous project that are necessary to carry out the developmental study; ii) the developmental expression of growth-related genes and their cellular localization; iii) tissue-specific expression and effect of GH on expression of growth-related genes; iv) possible relationship between GH gene structure, growth rate and genetic selection; v) the possible role of the IGF system in gonadal development. The major findings of our research can be summarized as follows: 1) The cDNAs (complete or partial) coding for Sparus IGFBP-2, GH receptor and Pit-1 were cloned. Sequence comparison reveals that the primary structure of IGFBP-2 protein is 43-49% identical to that of zebrafish and other vertebrates. Intensive efforts resulted in cloning a fragment of 138 nucleotides, coding for 46 amino acids in the proximal end of the intracellular domain of GH receptor. This is the first fish GH receptor cDNA that had been cloned to date. The cloned fragment will enable us to complete the GH - receptor cloning. 2) IGF-I, IGF-II, IGFBP-2, and IGF receptor transcripts were detected by RT-PCR method throughout development in unfertilized eggs, embryos, and larvae suggesting that these mRNAs are products of both the maternal and the embryonic genomes. Preliminary RT-PCR analysis suggest that GH receptor transcript is present in post-hatching larvae already on day 1. 3) IGF-1R transcripts were detected in all tissues tested by RT-PCR with highest levels in gill cartilage, skin, kidney, heart, pyloric caeca, and brain. Northern blot analysis detected IGF receptor only in gonads, brain and gill cartilage but not in muscle; GH increased slightly brain and gill cartilage IGF-1R mRNA levels. 4) IGFBP-2 transcript were detected only in liver and gonads, when analyzed by Northern blots; RT-PCR analysis revealed expression in all tissues studied, with the highest levels found in liver, skin, gonad and pyloric caeca. 5) Expression of IGF-I, IGF-II, IGF-1R and IGFBP-2 was analyzed during gonadal development. High levels of IGF-I and IGFBP-2 expression were found in bisexual young gonads, which decreased during gonadal development. Regardless of maturational stage, IGF-II levels were higher than those of IGF-L 6) The GH gene was cloned and its structure was characterized. It contains minisatellites of tandem repeats in the first and third introns that result in high level of genetic polymorphism. 7) Analysis of the presence of IGF-I and two types of IGF receptor by immunohistochemistry revealed tissue- and stage-specific expression during larval development. Immunohistochemistry also showed that IGF-I and its receptors are present in both testicular and ovarian cells. Although at this stage we are not able to pinpoint which is the rate-limiting step causing the slow growth of Sparus aurata, our project (together with the previous BARD) yielded a great number of experimental tools both DNA probes and antibodies that will enable further studies on the factors regulating growth in Sparus aurata. Our expression studies and cellular localization shed new light on the tissue and developmental expression of growth-related genes in fish.
4
Vaughan, George M., Basil A. Pruitt, Shirani Jr, Vaughan Khan, Mason Mary K., and Jr Arthur D. The Thyroid Axis and Brain 5'-Monodeiodination of Thyroxine in the Burned Rat Model of Nonthyroidal Illness. Fort Belvoir, VA: Defense Technical Information Center, January 1986. http://dx.doi.org/10.21236/ada185205.
5
Gantzer, Clark J., Shmuel Assouline, and Stephen H. Anderson. Synchrotron CMT-measured soil physical properties influenced by soil compaction. United States Department of Agriculture, February 2006. http://dx.doi.org/10.32747/2006.7587242.bard.
Анотація:
Methods to quantify soil conditions of pore connectivity, tortuosity, and pore size as altered by compaction were done. Air-dry soil cores were scanned at the GeoSoilEnviroCARS sector at the Advanced Photon Source for x-ray computed microtomography of the Argonne facility. Data was collected on the APS bending magnet Sector 13. Soil sample cores 5- by 5-mm were studied. Skeletonization algorithms in the 3DMA-Rock software of Lindquist et al. were used to extract pore structure. We have numerically investigated the spatial distribution for 6 geometrical characteristics of the pore structure of repacked Hamra soil from three-dimensional synchrotron computed microtomography (CMT) computed tomographic images. We analyzed images representing cores volumes 58.3 mm³ having average porosities of 0.44, 0.35, and 0.33. Cores were packed with < 2mm and < 0.5mm sieved soil. The core samples were imaged at 9.61-mm resolution. Spatial distributions for pore path length and coordination number, pore throat size and nodal pore volume obtained. The spatial distributions were computed using a three-dimensional medial axis analysis of the void space in the image. We used a newly developed aggressive throat computation to find throat and pore partitioning for needed for higher porosity media such as soil. Results show that the coordination number distribution measured from the medial axis were reasonably fit by an exponential relation P(C)=10⁻C/C0. Data for the characteristic area, were also reasonably well fit by the relation P(A)=10⁻ᴬ/ᴬ0. Results indicates that compression preferentially affects the largest pores, reducing them in size. When compaction reduced porosity from 44% to 33%, the average pore volume reduced by 30%, and the average pore-throat area reduced by 26%. Compaction increased the shortest paths interface tortuosity by about 2%. Soil structure alterations induced by compaction using quantitative morphology show that the resolution is sufficient to discriminate soil cores. This study shows that analysis of CMT can provide information to assist in assessment of soil management to ameliorate soil compaction.
6
Eshed, Yuval, and John Bowman. Harnessing Fine Scale Tuning of Endogenous Plant Regulatory Processes for Manipulation of Organ Growth. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696519.bard.
Анотація:
Background and objectives: Manipulation of plant organ growth is one of the primary reasons for the success of mankind allowing increasing amounts of food for human and livestock consumption. In contrast with the successful selection for desirable growth characteristics using plant breeding, transgenic manipulations with single genes has met limited success. While breeding is based on accumulation of many small alterations of growth, usually arise from slight changes in expression patterns, transgenic manipulations are primarily based on drastic, non-specific up-regulation or knock down of genes that can exert different effects during different stages of development. To successfully harness transgenic manipulation to attain desirable plant growth traits we require the tools to subtly regulate the temporal and spatial activity of plant growth genes. Polar morphology along the adaxial/abaxial axis characterizes lateral organs of all plants. Juxtaposition of two cell types along this axis is a prerequisite of laminar growth induction. In the study summarized here, we addressed the following questions: Can we identify and harness components of the organ polarity establishment pathway for prolonged growth? Can we identify specific regulatory sequences allowing spatial and temporal manipulation in various stages of organ development? Can we identify genes associated with YABBY-induced growth alterations? Major conclusions and implications: We showed that regulated expression, both spatially and temporally of either organ polarity factors such as the YABBY genes, or the organ maturation program such as the CIN-TCPs can stimulate substantial growth of leaves and floral organs. Promoters for such fine manipulation could be identified by comparison of non-coding sequences of KAN1, where a highly conserved domain was found within the second intron, or by examination of multiple 5” regions of genes showing transient expression along leaf ontogeny. These promoters illustrate the context dependent action of any gene we examined thus far, and facilitate fine tuning of the complex growth process. Implications, both scientific and agricultural. The present study was carried out on the model organism Arabidopsis, and the broad application of its findings were tested in the tomato crop. We learned that all central regulators of organ polarity are functionally conserved, probably in all flowering plants. Thus, with minor modifications, the rules and mechanisms outlined in this work are likely to be general.
7
Funkenstein, Bruria, and Shaojun (Jim) Du. Interactions Between the GH-IGF axis and Myostatin in Regulating Muscle Growth in Sparus aurata. United States Department of Agriculture, March 2009. http://dx.doi.org/10.32747/2009.7696530.bard.
Анотація:
Growth rate of cultured fish from hatching to commercial size is a major factor in the success of aquaculture. The normal stimulus for muscle growth in growing fish is not well understood and understanding the regulation of muscle growth in fish is of particular importance for aquaculture. Fish meat constitutes mostly of skeletal muscles and provides high value proteins in most people's diet. Unlike mammals, fish continue to grow throughout their lives, although the size fish attain, as adults, is species specific. Evidence indicates that muscle growth is regulated positively and negatively by a variety of growth and transcription factors that control both muscle cell proliferation and differentiation. In particular, growth hormone (GH), fibroblast growth factors (FGFs), insulin-like growth factors (IGFs) and transforming growth factor-13 (TGF-13) play critical roles in myogenesis during animal growth. An important advance in our understanding of muscle growth was provided by the recent discovery of the crucial functions of myostatin (MSTN) in controlling muscle growth. MSTN is a member of the TGF-13 superfamily and functions as a negative regulator of skeletal muscle growth in mammals. Studies in mammals also provided evidence for possible interactions between GH, IGFs, MSTN and the musclespecific transcription factor My oD with regards to muscle development and growth. The goal of our project was to try to clarify the role of MSTNs in Sparus aurata muscle growth and in particular determine the possible interaction between the GH-IGFaxis and MSTN in regulating muscle growth in fish. The steps to achieve this goal included: i) Determining possible relationship between changes in the expression of growth-related genes, MSTN and MyoD in muscle from slow and fast growing sea bream progeny of full-sib families and that of growth rate; ii) Testing the possible effect of over-expressing GH, IGF-I and IGF-Il on the expression of MSTN and MyoD in skeletal muscle both in vivo and in vitro; iii) Studying the regulation of the two S. aurata MSTN promoters and investigating the possible role of MyoD in this regulation. The major findings of our research can be summarized as follows: 1) Two MSTN promoters (saMSTN-1 and saMSTN-2) were isolated and characterized from S. aurata and were found to direct reporter gene activity in A204 cells. Studies were initiated to decipher the regulation of fish MSTN expression in vitro using the cloned promoters; 2) The gene coding for saMSTN-2 was cloned. Both the promoter and the first intron were found to be polymorphic. The first intron zygosity appears to be associated with growth rate; 3) Full length cDNA coding for S. aurata growth differentiation factor-l I (GDF-II), a closely related growth factor to MSTN, was cloned from S. aurata brain, and the mature peptide (C-terminal) was found to be highly conserved throughout evolution. GDF-II transcript was detected by RT -PCR analysis throughout development in S. aurata embryos and larvae, suggesting that this mRNA is the product of the embryonic genome. Transcripts for GDF-Il were detected by RT-PCR in brain, eye and spleen with highest level found in brain; 4) A novel member of the TGF-Bsuperfamily was partially cloned from S. aurata. It is highly homologous to an unidentified protein (TGF-B-like) from Tetraodon nigroviridisand is expressed in various tissues, including muscle; 5) Recombinant S. aurata GH was produced in bacteria, refolded and purified and was used in in vitro and in vivo experiments. Generally, the results of gene expression in response to GH administration in vivo depended on the nutritional state (starvation or feeding) and the time at which the fish were sacrificed after GH administration. In vitro, recombinantsaGH activated signal transduction in two fish cell lines: RTHI49 and SAFI; 6) A fibroblastic-like cell line from S. aurata (SAF-I) was characterized for its gene expression and was found to be a suitable experimental system for studies on GH-IGF and MSTN interactions; 7) The gene of the muscle-specific transcription factor Myogenin was cloned from S. aurata, its expression and promoter activity were characterized; 8) Three genes important to myofibrillogenesis were cloned from zebrafish: SmyDl, Hsp90al and skNAC. Our data suggests the existence of an interaction between the GH-IGFaxis and MSTN. This project yielded a great number of experimental tools, both DNA constructs and in vitro systems that will enable further studies on the regulation of MSTN expression and on the interactions between members of the GHIGFaxis and MSTN in regulating muscle growth in S. aurata.
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Yahav, Shlomo, John Brake, and Noam Meiri. Development of Strategic Pre-Natal Cycling Thermal Treatments to Improve Livability and Productivity of Heavy Broilers. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7593395.bard.
Анотація:
The necessity to improve broiler thermotolerance and live performance led to the following hypothesis: Appropriate comprehensive incubation treatments that include significant temperature management changes will promote angiogenesis and will improve acquisition of thermotolerance and carcass quality of heavy broilers through epigenetic adaptation. It was based on the following questions: 1. Can TM during embryogenesis of broilers induce a longer-lasting thermoregulatory memory (up to marketing age of 10 wk) that will improve acquisition of thermotolerance as well as increased breast meat yield in heavy broilers? 2. The improved sensible heat loss (SHL) suggests an improved peripheral vasodilation process. Does elevated temperature during incubation affect vasculogenesis and angiogenesis processes in the chick embryo? Will such create subsequent advantages for heavy broilers coping with adverse hot conditions? 3. What are the changes that occur in the PO/AH that induce the changes in the threshold response for heat production/heat loss based on the concept of epigenetic temperature adaptation? The original objectives of this study were as follow: a. to assess the improvement of thermotolerance efficiency and carcass quality of heavy broilers (~4 kg); b. toimproveperipheral vascularization and angiogenesis that improve sensible heat loss (SHL); c. to study the changes in the PO/AH thermoregulatory response for heat production/losscaused by modulating incubation temperature. To reach the goals: a. the effect of TM on performance and thermotolerance of broilers reared to 10 wk of age was studied. b. the effect of preincubation heating with an elevated temperature during the 1ˢᵗ 3 to 5 d of incubation in the presence of modified fresh air flow coupled with changes in turning frequency was elucidated; c.the effect of elevated temperature on vasculogenesis and angiogenesis was determined using in ovo and whole embryo chick culture as well as HIF-1α VEGF-α2 VEGF-R, FGF-2, and Gelatinase A (MMP2) gene expression. The effects on peripheral blood system of post-hatch chicks was determined with an infrared thermal imaging technique; c. the expression of BDNF was determined during the development of the thermal control set-point in the preoptic anterior hypothalamus (PO/AH). Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” Recently, Piestunet al. (2008) demonstrated for the first time that TM (an elevated incubation temperature of 39.5°C for 12 h/d from E7 to E16) during the development/maturation of the hypothalamic-hypophyseal-thyroid axis (thermoregulation) and the hypothalamic-hypophyseal-adrenal axis (stress) significantly improved the thermotolerance and performance of broilers at 35 d of age. These phenomena raised two questions that were addressed in this project: 1. was it possible to detect changes leading to the determination of the “set point”; 2. Did TM have a similar long lasting effect (up to 70 d of age)? 3. Did other TM combinations (pre-heating and heating during the 1ˢᵗ 3 to 5 d of incubation) coupled with changes in turning frequency have any performance effect? The improved thermotolerance resulted mainly from an efficient capacity to reduce heat production and the level of stress that coincided with an increase in SHL (Piestunet al., 2008; 2009). The increase in SHL (Piestunet al., 2009) suggested an additional positive effect of TM on vasculogenesis and angiogensis. 4. In order to sustain or even improve broiler performance, TM during the period of the chorioallantoic membrane development was thought to increase vasculogenesis and angiogenesis providing better vasodilatation and by that SHL post-hatch.
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Yaron, Zvi, Abigail Elizur, Martin Schreibman, and Yonathan Zohar. Advancing Puberty in the Black Carp (Mylopharyngodon piceus) and the Striped Bass (Morone saxatilis). United States Department of Agriculture, January 2000. http://dx.doi.org/10.32747/2000.7695841.bard.
Анотація:
Both the genes and cDNA sequences encoding the b-subunits of black carp LH and FSH were isolated, cloned and sequenced. Sequence analysis of the bcFSHb and LHb5'flanking regions revealed that the promoter region of both genes contains canonical TATA sequences, 30 bp and 17 bp upstream of the transcription start site of FSHb and LHb genes, respectively. In addition, they include several sequences of cis-acting motifs, required for inducible and tissue-specific transcriptional regulation: the gonadotropin-specific element (GSE), GnRH responsive element (GRE), half sites of estrogen and androgen response elements, cAMP response element, and AP1. Several methods have been employed by the Israeli team to purify the recombinant b subunits (EtOH precipitation, gel filtration and lentil lectin). While the final objective to produce pure recombinantGtH subunits has not yet been achieved, we have covered much ground towards this goal. The black carp ovary showed a gradual increase in both mass and oocyte diameter. First postvitellogenic oocytes were found in 5 yr old fish. At this age, the testes already contained spermatozoa. The circulating LH levels increased from 0.5 ng/ml in 4 yr old fish to >5ng/ml in 5 yr old fish. In vivo challenge experiments in black carp showed the initial LH response of the pituitary to GnRH in 4 yr old fish. The response was further augmented in 5 yr old fish. The increase in estradiol level in response to gonadotropic stimulation was first noted in 4 yr old fish but this response was much stronger in the following year. In vivo experiments on the FSHb and LHb mRNA levels in response to GnRH were carried out on common carp as a model for synchronom spawning cyprinids. These experiments showed the prevalence of FSHP in maturing fish while LHP mRNA was prevalent in mature fish, especially in females. The gonadal fat-pad was found to originate from the retroperitoneal mesoderm and not from the genital ridge, thus differing from that reported in certain amphibians This tissue possibly serves as the major source of sex steroids in the immature black carp. However, such a function is taken over by the developing gonads in 4 yr old fish. In the striped bass, we described the ontogeny of the neuro-endocrine parameters along the brain-pituitary-gonadal axis during the first four years of life, throughout gonadal development and the onset of puberty. We also described the responsiveness of the reproductive axis to long-term hormonal manipulations at various stages of gonadal development. Most males reached complete sexual maturity during the first year of life. Puberty was initiated during the third year of life in most females, but this first reproductive cycle did not lead to the acquisition of full sexual maturity. This finding indicates that more than one reproductive cycle may be required before adulthood is reached. Out of the three native GnRHs present in striped bass, only sbGnRH and cGnRH II increased concomitantly with the progress of gonadal development and the onset of puberty. This finding, together with data on GtH synthesis and release, suggests that while sbGnRH and cGnRH II may be involved in the regulation of puberty in striped bass, these neuropeptides are not limiting factors to the onset of puberty. Plasma LH levels remained low in all fish, suggesting that LH plays only a minor role in early gonadal development. This hypothesis was further supported by the finding that experimentally elevated plasma LH levels did not result in the induction of complete ovarian and testicular development. The acquisition of complete puberty in 4 yr old females was associated with a rise in the mRNA levels of all GtH subunit genes, including a 218-fold increase in the mRNA levels of bFSH. mRNA levels of the a and PLH subunits increased only 11- and 8-fold, respectively. Although data on plasma FSH levels are unavailable, the dramatic increase in bFSH mRNA suggests a pivotal role for this hormone in regulating the onset and completion of puberty in striped bass. The hormonal regulation of the onset of puberty and of GtH synthesis and release was studied by chronic administration of testosterone (T) and/or an analog of gonadotropin-releasing hormone (G). Sustained administration of T+G increased the mRNA levels of the PLH subunit to the values characteristic of sexually mature fish, and also increased the plasma levels of LH. However, these changes did not result in the acceleration of sexual maturation. The mRNA levels of the bFSH subunit were slightly stimulated, but remained about 1/10 of the values characteristic of sexually mature fish. It is concluded that the stimulation of FSH gene expression and release does not lead to the acceleration of sexual maturity, and that the failure to sufficiently stimulate the bFSH subunit gene expression may underlie the inability of the treatments to advance sexual maturity. Consequently, FSH is suggested to be the key hormone to the initiation and completion of puberty in striped bass. Future efforts to induce precocious puberty in striped bass should focus on understanding the regulation of FSH synthesis and release and on developing technologies to induce these processes. Definite formulation of hormonal manipulation to advance puberty in the striped bass and the black carp seems to be premature at this stage. However, the project has already yielded a great number of experimental tools of DNA technology, slow-release systems and endocrine information on the process of puberty. These systems and certain protocols have been already utilized successfully to advance maturation in other fish (e.g. grey mullet) and will form a base for further study on fish puberty.
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Dudley, Lynn M., Uri Shani, and Moshe Shenker. Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586468.bard.
Анотація:
Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.