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Добірка наукової літератури з теми "2.5 geometry"

Автор: Grafiati

Опубліковано: 3 вересня 2022

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Статті в журналах з теми "2.5 geometry"

Smits, P. R. J. M., and J. C. W. Van Vroonhoven. "The polarities of the partial geometry pg(5, 5, 2)." Geometriae Dedicata 21, no. 1 (August 1986): 51–54. http://dx.doi.org/10.1007/bf00147529.

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Hahn, Jae Ryang, Gyu-Hyeong Kim, Ki Wan Kim, and Sukmin Jeong. "Binding geometry of furan on Si(5 5 12)−2×1." Surface Science 616 (October 2013): 166–70. http://dx.doi.org/10.1016/j.susc.2013.05.019.

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Uçum, Ali, Kazım İlarslan, and Makoto Sakaki. "k-Type bi-null slant helices in $$\mathbb {R}_{2}^{5}$$ R 2 5." Journal of Geometry 108, no. 3 (May 8, 2017): 913–24. http://dx.doi.org/10.1007/s00022-017-0385-z.

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Martí Sánchez, María. "Surfaces with $${K^2=2\mathcal{X}-2}$$ and p g ≥ 5." Geometriae Dedicata 150, no. 1 (April 8, 2010): 49–61. http://dx.doi.org/10.1007/s10711-010-9493-8.

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Basto-Gonçalves, J., and H. Reis. "The Geometry of 2 × 2 Systems of Conservation Laws." Acta Applicandae Mathematicae 88, no. 3 (September 2005): 269–329. http://dx.doi.org/10.1007/s10440-005-9002-5.

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Larke, Patricia J. "Geometric Extravaganza: Spicing Up Geometry." Arithmetic Teacher 36, no. 1 (September 1988): 12–16. http://dx.doi.org/10.5951/at.36.1.0012.

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If we can have science fairs, why not geometry fairs? They are excellent ways for elementary teachers to add pizzazz to the teaching of geometry. A geometry fair or geometric extravaganza is a display or exhibit of geometry projects representing the students' culminating work in a geometry unit. The purposes of a geometry fair a re (I) to remind students of important geometric terms and concepts; (2) to enable students to explore the world of lines, angles, points, and geometric shapes; (3) to help students identify and construct geome tric shapes and designs; (4) to help students prepare projects using their knowledge of geometry and creativity; and (5) to help students share work with othe rs. thus building pride in their work.

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Shaw, Ron. "Trivectors yielding spreads in PG(5, 2)." Journal of Geometry 96, no. 1-2 (December 2009): 149–65. http://dx.doi.org/10.1007/s00022-010-0030-6.

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Shaw, Ron. "Trivectors and cubics: PG(5, 2) aspects." Journal of Geometry 99, no. 1-2 (December 2010): 167–78. http://dx.doi.org/10.1007/s00022-011-0060-8.

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Ling, Alan C. H. "On 2-chromatic (v, 5, 1)-designs." Journal of Geometry 66, no. 1-2 (November 1999): 144–48. http://dx.doi.org/10.1007/bf01225678.

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Hussain, Saghir, Yang Deli, Shagufta Parveen, Xin Hao, and Changjin Zhu. "Bis[5-methoxy-2-(methoxycarbonyl)phenyl] methylphosphonate." Acta Crystallographica Section E Structure Reports Online 70, no. 3 (February 12, 2014): o269. http://dx.doi.org/10.1107/s1600536814002542.

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In the title phosphonate, C19H21O9P, the dihedral angle between the benzene rings is 63.33 (3)°, and the P atom has a distorted tetrahedral geometry, with angles in the range 101.30 (6)–120.38 (6)°. No significant intermolecular interactions are observed in the crystal structure, and π–π interactions between symmetry-related benzene rings are beyond 4 Å.

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Дисертації з теми "2.5 geometry"

Gier, Megan E. "EIGENVALUE MULTIPLICITES OF THE HODGE LAPLACIAN ON COEXACT 2-FORMS FOR GENERIC METRICS ON 5-MANIFOLDS." UKnowledge, 2014. http://uknowledge.uky.edu/math_etds/14.

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In 1976, Uhlenbeck used transversality theory to show that for certain families of elliptic operators, the property of having only simple eigenvalues is generic. As one application, she proved that on a closed Riemannian manifold, the eigenvalues of the Laplace-Beltrami operator Δg are all simple for a residual set of Cr metrics. In 2012, Enciso and Peralta-Salas established an analogue of Uhlenbeck's theorem for differential forms, showing that on a closed 3-manifold, there exists a residual set of Cr metrics such that the nonzero eigenvalues of the Hodge Laplacian Δg(k) on k-forms are all simple for 0 ≤ k ≤ 3. In this dissertation, we continue to address the question of whether Uhlenbeck's theorem can be extended to differential forms. In particular, we prove that for a residual set of Cr metrics, the nonzero eigenvalues of the Hodge Laplacian Δg(2) acting on coexact 2-forms on a closed 5-manifold have multiplicity 2. To prove our main result, we structure our argument around a study of the Beltrami operator *gd, which is related to the Hodge Laplacian by Δg(2) = -(*gd)2 when the operators are restricted to coexact 2-forms on a 5-manifold. We use techniques from perturbation theory to show that the Beltrami operator has only simple eigenvalues for a residual set of metrics. We further establish even eigenvalue multiplicities for the Hodge Laplacian acting on coexact k-forms in the more general setting n = 4 ℓ + 1 and k = 2 ℓ for ℓ ϵ N.

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ASSIS, Lilian Pureza de. "Otimização de estruturas reticuladas planas com comportamento geometricamente não linear." Universidade Federal de Goiás, 2006. http://repositorio.bc.ufg.br/tede/handle/tde/678.

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Made available in DSpace on 2014-07-29T15:03:39Z (GMT). No. of bitstreams: 1 lilian pureza.pdf: 2774999 bytes, checksum: 2a074d04ee02c7e1c87fdbe8c2c68ef6 (MD5) Previous issue date: 2006-10-20
The aim of this work is to present a formulation and corresponding computational implementation for sizing optimization of plane frames and cable-stayed columns considering geometric non liner behavior. The structural analysis is based on the finite element method using the updated lagrangian approach for plane frame and cable elements, which are represented by plane truss elements. The non linear system is solved by the Newton-Raphson method coupled to load increment strategies such as the arch length method and the generalized displacement parameter method, which allow the algorithm to transpose any critical point that happen to appear along the equilibrium path. In the optimization process the design variables are the heights of the crosssection of the frame elements, the objective function represents the volume of the structure and the constraints impose limits to displacements and critical load. Lateral constraints impose limits to the design variables. The finite difference method is used in the sensitivity analysis of the displacement and critical load constraints. The optimization process is carried out using three different optimization strategies: the sequential quadratic programming algorithm; the interior points algorithm; and the branch and bound method. Some numerical experiments are carried out so as to test the analysis and the sensitivity strategies. Numerical experiments are presented to show the validity of the implementation presented in this dissertation.
O objetivo deste trabalho é a otimização de dimensões de pórticos planos e de colunas estaiadas planas pela minimização do volume da estrutura, considerando os efeitos da não-linearidade geométrica em seu comportamento. A formulação utiliza, para análise das estruturas, elementos finitos de pórtico e de treliça planos e referencial lagrangeano atualizado. O método de Newton-Raphson foi utilizado como estratégia para solução do sistema de equações não lineares. Foram acopladas estratégias especiais para ultrapassagem de pontos críticos que possam existir ao longo da trajetória de equilíbrio, tais como o comprimento de arco cilíndrico e o controle dos deslocamentos generalizados. Na otimização, as variáveis de projeto são as alturas das seções transversais dos elementos, a função objetivo é o volume do material e as restrições dizem respeito a limitações impostas a deslocamentos e à carga limite, além de limitações impostas aos valores das variáveis. A sensibilidade da função objetivo foi obtida por diferenciação direta e a sensibilidade das restrições pelo método das diferenças finitas. Foram utilizados o algoritmo de programação quadrática seqüencial, PQS, o algoritmo de pontos interiores, PI, e o algoritmo de Branch and Bound, B&B. São apresentados exemplos de validação das estratégias de análise não linear e da análise de sensibilidade, além dos exemplos de validação da formulação empregada para a otimização resolvidos pelos métodos implementados.

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Frini, Marouane. "Diagnostic des engrenages à base des indicateurs géométriques des signaux électriques triphasés." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSES052.

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Bien qu’ils soient largement utilisés dans le domaine, les mesures vibratoires classiques présentent plusieurs limites. A la base, l’analyse vibratoire ne peut identifier qu’environ 60% des défauts qui peuvent survenir dans les machines. Cependant, les principaux inconvénients des mesures de la vibration sont l’accès difficile au système de transmission afin d’y placer le capteur ainsi que le coût conséquent de la mise en œuvre. Ceci résulte en des problèmes de sensibilité relatifs à la position de l’installation et ceux de difficulté pour distinguer la source de vibration à cause de la diversité des excitations mécaniques qui existent dans l’environnement industriel.Par conséquent, l’analyse des signatures du courant électrique des moteurs s’impose comme une alternative prometteuse à l’analyse vibratoire et a donc fait l’objet d’une attention grandissante au cours des dernières années. En effet, l’analyse des signatures électriques a l’avantage d’être une méthode techniquement accessible, non-intrusive au système et peu coûteuse. Les techniques basées sur le courant et la tension ne requièrent que les mesures électriques du moteur qui sont souvent déjà surveillées pour le contrôle et la protection des machines électriques. Ce processus a été principalement utilisé pour la détection des défauts de moteur tels que la rupture de barres du rotor et les défauts d’excentricité ainsi que les défauts de roulements. En revanche, très peu de recherches concernent la détection des défauts en utilisant l’analyse du courant. En outre, les signaux électriques triphasés sont caractérisés par des représentations géométriques particulières liées à leur forme d’onde qui peuvent servir en tant qu’indicateurs différents offrant des informations supplémentaires. Parmi ces indicateurs géométriques, les transformées de Park et de Concordia modélisent les composantes électriques dans un repère bidimensionnel et toute déviation par rapport à la représentation d’origine indique l’apparition d’un dysfonctionnement. Aussi, les équations différentielles de Frenet-Serret représentent la trajectoire du signal dans un espace euclidien tridimensionnel et indiquent ainsi tout changement dans l’état du système. Bien qu’ils aient été utilisés pour les défauts de roulements, ces indicateurs n’ont pas été appliqués dans la détection des défauts d’engrenages en utilisant l’analyse des signatures des courants électriques. D’où l’idée novatrice de combiner ces indicateurs avec des techniques de traitement de signal, ainsi que des techniques de classification pour le diagnostic des engrenages en utilisant l’analyse des signatures de courant et de tension du moteur électrique.Ainsi, dans ce travail, on propose une nouvelle approche pour le diagnostic des défauts d’engrenages en utilisant l’analyse des courants et des tensions électriques du stator de la machine et ceci en se basant sur un ensemble d’indicateurs géométriques (Transformées de Park et de Concordia ainsi que les propriétés du repère Frenet-Serret). Ces indicateurs font partie d’une bibliothèque de signatures de défauts qui a été construite et qui comprend également les indicateurs classiques utilisés pour un large éventail de défauts. Ainsi, un algorithme combine les acquisitions expérimentales des signaux électriques à des méthodes de traitement de signal avancées (décomposition modale empirique,…). Ensuite, celui-ci sélectionne les indicateurs les plus pertinents au sein de la bibliothèque en se basant sur les algorithmes de sélection de paramètres (sélection séquentielle rétrograde et analyse des composantes principales). Enfin, cette sélection est utilisée pour la classification non-supervisée (K-moyennes) pour la distinction entre l’état sain et l’état défaillant
Although they are widely used, classical vibration measurements have several limitations. Vibration analysis can only identify about 60% of the defects that may occur in mechanical systems. However, the main drawbacks of vibration measurements are the difficult access to the transmission system in order to place the sensor as well as the consequent cost of implementation. This results in sensitivity problems relative to the position of the installation and the difficulty to distinguish the source of vibration because of the diversity of mechanical excitations that exist in the industrial environment.Hence, the Motor Current Signatures Analysis (M.C.S.A.) represents a promising alternative to the vibration analysis and has therefore been the subject of increasing attention in recent years. Indeed, the analysis of electrical signatures has the advantage of being a technically accessible method as well as inexpensive and non-intrusive to the system. Techniques based on currents and voltages only require the motor’s electrical measurements which are often already supervised for the purposes of the control and the protection of the electrical machines. This process was mainly used for the detection of motors faults such as rotor bars breakage and eccentricity faults as well as bearings defects. On the other hand, very little research has been focused on gear faults detection using the current analysis. In addition, three-phase electrical signals are characterized by specific geometric representations related to their waveforms and they can serve as different indicators providing additional information. Among these geometric indicators, the Park and Concordia transforms model the electrical components in a two-dimensional coordinate system and any deviation from the original representation indicates the apparition of a malfunction. Moreover, the differential equations of Frenet-Serret represent the trajectory of the signal in a three-dimensional euclidean space and thus indicate any changes in the state of the system. Although they have been previously used for bearing defects, these indicators have not been applied in the detection of gear defects using the analysis of electrical current signatures. Hence, the innovative idea of combining these indicators with signal processing techniques, as well as classification techniques for gears diagnosis using the three-phase motor’s electrical current signatures analysis is established.Hence, in this work, a new approach is proposed for gear faults diagnosis using the motor currents analysis, based on a set of geometric indicators (Park and Concordia transforms as well as the properties of the Frenet-Serret frame). These indicators are part of a specifically built fault signatures library and which also includes the classical indicators used for a wide range of faults. Thus, a proposed estimation algorithm combines experimental measurements of electrical signals with advanced signal processing methods (Empirical Mode Decomposition, ...). Next, it selects the most relevant indicators within the library based on feature selection algorithms (Sequential Backward Selection and Principal Component Analysis). Finally, this selection is combined with non-supervised classification (K-means) for the distinction between the healthy state and faulty states. It was finally validated with a an additional experimental configuration in different cases with gear faults, bearing faults and combined faults with various load levels

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DANTLO, Nicolas, and NicolasDantlo. "Automated tool selection and tool path generation based on 2-D geometry for 5-axis free-form milling." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/20991987763923838180.

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碩士
國立交通大學
機械工程系
91
This paper presents an algorithm for cutting tool selection and tool path generation for five-axis finish surface milling. The tool selection and tool path generation is based on the curvature of the surface along its principal components. The investigated tool parameters are the tool diameter, the tool edge radius and the tool length. Those parameters are compared to a standard tool library, to ensure an optimized tool selection. The investigated tool path is a lace cutting tool path, where the constant parameter is selected from the surface curvatures. The investigated tool orientation will ensure a maximal removal rate, and an over-cut and under-cut inferior to the surface tolerance. All these parameters will allow finding the most appropriate tool from a library and the shortest tool path length.

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Книги з теми "2.5 geometry"

Shafarevich, Igor R. Basic Algebraic Geometry 2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38010-5.

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Convegno, italiano di geometria integrale probabilità geometriche e. corpi convessi (4th 1994 Bari Italy). IV Convegno italiano di geometria integrale, probabilità geometriche e corpi convessi: Bari, 2-5 maggio 1994. Palermo: Sede della società, 1995.

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1952-, Brooks Robert, Entov Michael 1969-, Pinchover Yehuda 1953-, Sageev Michah 1966-, and Workshop on Groups, Geometry, and Dynamics (2004 : Haifa, Israel), eds. Geometry, spectral theory, groups, and dynamics: Proceedings in memory of Robert Brooks, December 29, 2003-January 2, 2004 [and] January 5-9, 2004, Technion-Israel Institute of Technology, Haifa, Israel. Providence, R.I: American Mathematical Society, 2005.

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1959-, Blasco Oscar, and Universidad Politécnica de Valencia, eds. Topics in complex analysis and operator theory: Third Winter School Complex Analysis and Operator theory, February 2-5, 2010, Universidad Politécnica de Valencia, Valencia, Spain. Providence, R.I: American Mathematical Society, 2012.

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Nuffield Mathematics 5-11 (Nuffield Maths 5-11 Project). Longman, 1990.

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(Editor), Jan Denef, Leonard Lipshitz (Editor), Thanases Pheidas (Editor), and Jan Van Geel (Editor), eds. Hilbert's Tenth Problem: Relations With Arithmetic and Algebraic Geometry : Workshop on Hilbert's Tenth Problem : Relations With Arithemtic and Algebraic ... November 2-5 (Contemporary Mathematics). American Mathematical Society, 2001.

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1951-, Denef Jan, ed. Hilbert's tenth problem: Relations with arithmetic and algebraic geometry : workshop on Hilbert's tenth problem : relations with arithmetic and algebraic geometry, November 2-5, 1999, Ghent University, Belgium. Providence, R.I: American Mathematical Society, 2000.

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(Editor), Doug Clements, ed. Picturing Polygons: 2-D Geometry (Investigations in Number, Data, and Space, Grades 5-6) (MacIntosh Disk Included). Dale Seymour Publications, 1996.

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Laboratoire Gravitation et Cosmologie Re. Gravitation, Geometry and Relativistic Physics: Proceedings of the "Journees Relativistes" held at Aussois, France, May 2-5, 1984. Springer, 2014.

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Chruściel, Piotr T. Geometry of Black Holes. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198855415.001.0001.

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There exists a large scientific literature on black holes, including many excellent textbooks of various levels of difficulty. However, most of these prefer physical intuition to mathematical rigour. The object of this book is to fill this gap and present a detailed, mathematically oriented, extended introduction to the subject. The first part of the book starts with a presentation, in Chapter 1, of some basic facts about Lorentzian manifolds. Chapter 2 develops those elements of Lorentzian causality theory which are key to the understanding of black-hole spacetimes. We present some applications of the causality theory in Chapter 3, as relevant for the study of black holes. Chapter 4, which opens the second part of the book, constitutes an introduction to the theory of black holes, including a review of experimental evidence, a presentation of the basic notions, and a study of the flagship black holes: the Schwarzschild, Reissner–Nordström, Kerr, and Majumdar–Papapetrou solutions of the Einstein, or Einstein–Maxwell, equations. Chapter 5 presents some further important solutions: the Kerr–Newman–(anti-)de Sitter black holes, the Emperan–Reall black rings, the Kaluza–Klein solutions of Rasheed, and the Birmingham family of metrics. Chapters 6 and 7 present the construction of conformal and projective diagrams, which play a key role in understanding the global structure of spacetimes obtained by piecing together metrics which, initially, are expressed in local coordinates. Chapter 8 presents an overview of known dynamical black-hole solutions of the vacuum Einstein equations.

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Частини книг з теми "2.5 geometry"

"2 × 2 Linear Systems." In The Geometry Toolbox for Graphics and Modeling, 79–95. A K Peters/CRC Press, 2017. http://dx.doi.org/10.1201/9781315275550-5.

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Dodson, C. T. J. "Manifold Geometry." In Encyclopedia of Physical Science and Technology, 49–76. Elsevier, 2003. http://dx.doi.org/10.1016/b0-12-227410-5/00400-2.

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Ashtekar, A., and J. Lewandowski. "Quantum Geometry and Its Applications." In Encyclopedia of Mathematical Physics, 230–36. Elsevier, 2006. http://dx.doi.org/10.1016/b0-12-512666-2/00231-5.

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"5 Lattices and their Voronoï and Delone cells." In Introduction to Louis Michel's lattice geometry through group action, 81–100. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1952-2-006.

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Shaw, Ron. "Double-fives and partial spreads in PG(5, 2)." In Geometry, Combinatorial Designs and Related Structures, 201–16. Cambridge University Press, 1997. http://dx.doi.org/10.1017/cbo9780511526114.018.

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BESTVINA, M. "ℝ-Trees in Topology, Geometry, and Group Theory." In Handbook of Geometric Topology, 55–91. Elsevier, 2001. http://dx.doi.org/10.1016/b978-044482432-5/50003-2.

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Berkane, Maia, and Peter M. Bentler. "The geometry of mean or covariance structure models in multivariate normal distributions: A unified approach." In Multivariate Analysis: Future Directions 2, 153–69. Elsevier, 1993. http://dx.doi.org/10.1016/b978-0-444-81531-6.50015-5.

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Grechneva, M. O., and P. G. Stegantseva. "Geometry of Grassmann image of the nonisotropic surface of Minkowski space." In Innovative paradigm of the development of modern physical-mathematical sciences, 18–41. Izdevnieciba “Baltija Publishing”, 2022. http://dx.doi.org/10.30525/978-9934-26-200-5-2.

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Amose, Yardily, Fathima Shahana, and Abbs Fen Reji. "Density Functional Theory and Molecular Modeling of the Compound 2-[2-(4-Methylphenylamino)-4-phenylthiazol-5-yl]benzofuran." In Furan Derivatives - Recent Advances and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99577.

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The compound 2-[2-(4-methylphenylamino)-4-phenylthiazol-5-yl]benzofuran was prepared from 1-(4-methylphenyl)-3-(N-phenylbenzimidoyl)thiourea and 2-(2-bromoacetyl) benzofuran in the presence of triethylamine and characterized by FTIR, NMR, and mass spectra. Density functional theory (DFT) computations were adopted for the geometry optimization of this compound, to evaluate their Mulliken atomic charge distribution, HOMO-LUMO energy gap, and vibrational analysis. The titled compound induced G1 cell cycle arrest, which is regulated by CDK2 in cancer cells. Therefore, we used molecular modeling to study in-silico for the possible inhibitory effect as a mechanism of this compound as anticancer agents (PDB code: 2KW6, 6DL7, 6VJO, 6WMW, and 7LAE). The molecular docking study revealed that the compound was the most effective in inhibiting CDk2 cancer cells.

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Тези доповідей конференцій з теми "2.5 geometry"

Ford, Matthew D., Sang-Wook Lee, Stephen P. Lownie, David W. Holdsworth, and David A. Steinman. "Geometry Anticipates Hemodynamic Phenotype of Basilar Tip Aneurysms." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-171979.

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The prevalence of unruptured cerebral aneurysms is estimated to be as high as 5% [1]. Basilar tip aneurysms account for 4–5% of these, but have a higher risk of rupture [2]. They are also difficult to treat surgically, and so endovascular therapy is often the only option. Hemodynamic forces have been implicated in the risk of rupture [3] and complications of endovascular therapy [4]; however, hemodynamic information is difficult to acquire clinically. Computational fluid dynamics (CFD), in combination with clinical imaging, can be used to accurately capture the intra-aneurysmal hemodynamics in a patient-specific manner [5]. Still, these techniques have not translated to routine clinical use, largely due to the time and effort required to construct, simulate, and interpret these models.

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Chevil, Karina, Abdoulmajid Eslami, Weixing Chen, Reg Eadie, Richard Kania, Robert Worthingham, and Greg Van Boven. "Developing Cathodic Protection Based on Disbondment Geometry." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90675.

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Coating disbondment on pipelines is a common phenomenon that leads to exposure of the pipeline metal to ground water solutions, promoting a corrosive environment which is associated with stress corrosion cracking (SCC). This investigation tracks the corrosion behavior of X-65 steel at different coating disbondments at Open Circuit Potential (OCP) conditions through weight loss tests, as well as SEM analysis. For the weight loss test, X-65 coupons were placed into a vertical coupon holder with varying gap sizes between the coupons and the shielding (2 mm 5 mm, and 10 mm) simulating the coating disbondment. The results of the tests suggest that the corrosion rate inside the gap is dependent on the mass transfer rate of CO2. For larger gaps, the corrosion rate inside the gap decreases almost linearly with position (highest at the top of the disbondment) and is dependent on the iron carbonate film deposition. For smaller gaps (≤5 mm) a galvanic effect was observed between the coupons at the top of the disbondment (anodic) which showed a high degree of general corrosion, and the coupons at the bottom of the disbondment (cathodic) which had very low corrosion rates. The experimental observations were related to the corrosion scenarios found in the field. Cathodic protection strategies with respect to the geometry of disbondment are also discussed.

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Wang, Hanlin, and Lesley M. Wright. "Effect of Inlet Geometry on Flat Plate, Film Cooling Effectiveness From Shaped Holes." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73135.

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Abstract Modern gas turbine engines require a sophisticated cooling system design to achieve higher power output and efficiency. In this study, systematic tests were carried out to evaluate the potential effect of non-cylindrical inlet geometries on the performance of laid back, fan-shaped film cooling holes using the pressure sensitive paint (PSP) measurement technique. A laid-back, fan-shaped hole outlet design in open literature was selected as the basis for the film cooling holes in this study, with varying inlet geometries. “Racetrack” shaped inlet geometries with aspect ratios of 2:1 and 4:1 were tested along with traditional cylindrical inlets. The coolant flow conditions range from blowing ratios of M = 0.3–1.5 and density ratios DR = 1 and 2. The mainstream turbulence intensity is fixed at 6%. Test results show that the shaped inlets can provide a higher area-averaged film cooling effectiveness, η, over the traditional cylindrical inlet design using the same amount of coolant. For the 2:1 inlet, an advantage of 20% higher η could be maintained for DR = 1, while for DR = 2 this advantage is reduced to 10%. For the 4:1 inlet, when the coolant momentum flux ratio I < 0.5, a similar or slightly higher improvement can be obtained, but when I > 1, the advantage diminishes with the growing momentum flux ratio to approximately 5%, at I = 2.25. In terms of discharge coefficients, the 2:1 inlet geometry is similar to the cylindrical inlet under most flow conditions. For the 4:1 inlet, its discharge coefficient is 2–5% lower than the fan-shaped holes with a cylindrical inlet, under the same flow conditions.

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Yuan, Haomin, Vakhtang Makarashvili, Elia Merzari, Aleksandr Obabko, and Yiqi Yu. "Large Eddy Simulations of a Coolant Flow in Spacer Grid Fuel Assemblies With a Spectral Element Solver." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81892.

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In this study we used Nek5000, an open-source, high-order spectral element CFD code developed at Argonne National Laboratory (ANL), to model the coolant flow in spacer grids. Two fuel assembly configurations were studied: 2 × 2 and 5 × 5 fuel rod arrangements. The simulations for the 2 × 2 case were based on previous studies, simulating one span of the 2 × 2 fuel rod configuration including a surrogate spacer grid and mixing vane design with typical features of spacers for energy production. Dual periodic boundary conditions were applied in the spanwise direction to take the crossflow into consideration. The study of the 5 × 5 fuel assembly was performed as part of the ANL–Framatome collaboration for advancing computational fluid dynamics (CFD) tools. An advanced numerical model was developed to simulate the experimental setup provided by Framatome. For the 5 × 5 fuel assembly study, two cases of flow geometry were simulated with Nek5000: balanced and unbalanced configurations. In the balanced flow the coolant was entering the fuel rod assembly through 121 uniformly spaced inlet holes arranged in an 11 × 11 matrix. The unbalanced case, on the other hand, featured 14 larger holes placed on only one side of the horizontal plane. Nek5000 accepts only hexahedral meshes, which bring a great challenge to the meshing process for a spacer grid fuel assembly. A tet-to-hex meshing strategy was applied to handle the complex geometric features. A tetrahedral mesh was created first, and then each tetrahedral element was converted into four hexahedral elements. Boundary layers were extruded to fit to the exact geometry. In order to account for transient flow characteristics, the large eddy simulation approach was applied in this study. The employed subgrid-scale model relies on explicit filtering, which has been proven valid for many engineering-scale simulations. We present here the simulation results obtained for both the 2 × 2 and 5 × 5 fuel assemblies.

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Sahari, Ali, Meghan Canter, and Bahareh Behkam. "Effect of Body Geometry on the Motile Behavior of Bacteriabots." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80901.

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Micro-structures with complex geometries are being increasingly utilized in many fields from micro-robotics to targeted drug delivery [1,2]. Motility of spherical microstructures actuated by an ensemble of attached bacteria has been thoroughly characterized in previous literature [2–5] but a systematic study of the effect of micro structure geometry on propulsive behavior is currently missing. Mobile microrobots along with optimal body geometries are envisioned to impact minimally invasive diagnosis, localized treatment of diseases and environmental monitoring. Limited particle diffusion and directional coefficient of drag are some of the attributes that are enhanced through such bio-hybrid systems. In this work, we have utilized a low-cost and high throughput technique to obtain non-spherical mico-particles and investigate the effect of particle shape on the motile behavior of the BacteriaBots, which are bio-hybrid microrobots consisting of living propellers (bacteria) and a synthetic body.

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Lee, Yuan-Shin, and Hong Ji. "Feasible Machining Strip Evaluation for 5-Axis CNC Die and Mold Machining." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1089.

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Abstract This research is focused on the investigation of robust surface interrogation tools which can support the planning and programming of 5-axis die/mold surface machining. Surface curvature information is evaluated to determine optimal tool orientation for 5-axis machining. A method for calculating machining strip width is proposed for 5-axis cutter path generation. This paper is focused on the development of computational geometry techniques and their application to design, analysis, and manufacturing automation. The proposed planning and programming methodology consists of two steps: 1) machining strip width evaluation, and 2) optimum tool orientation for 5-axis machining. This proposed research can be used to improve the quality of 5-axis die/mold machining.

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Mann, J. Adin, Brandon Yost, Gregory Westwater, Christopher R. Johnson, Brett Pollock, and Katharine Liu. "Validating FEA Simulations of Structural Collapse of a Complex Vessel Geometry." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63817.

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Part 5 in Section VIII Division 2 of the ASME Boiler & Pressure Vessel Code provides methods for evaluating stresses in pressure vessel components using Finite Element Analysis (FEA). Both linear elastic and inelastic methods are provided. Validating the FEA simulations can be challenging because of testing procedures as well as variation between the test parts. Control valve bodies, which have a complex geometry, were tested to pressures far beyond the maximum allowable working pressure to evaluate behavior at structural collapse. The test bodies were scanned so that the true geometry was used in the FEA simulations. FEA simulations were used to perform a linear elastic evaluation and inelastic evaluations. The inelastic evaluation included various material models. The difference between a point by point comparison and outcome based validation are discussed.

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Boyak, Craig. "A Comparative Study of Radial Nozzle Criteria; Section VIII, Division 2, Part 4.5.5 to Part 5.2.2." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-66583.

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Abstract A study is presented which compares nozzle thickness requirements based ASME Section VIII, Division 2, Parts 4 and 5[1]. Specifically, the simplified geometry of a set-in, radial nozzle without inward projection or repad is considered. The comparative technique considers a design pressure at the capacity of the shell and identifies the minimum nozzle thickness that satisfies applicable stress limits. For Part 4, the methodology of 4.5.5 is used. For Part 5, the elastic method in 5.2.2 is used. The study employs these techniques for R/t geometries of 20 to 180 and d/D ratios of 0.01 to 0.3. The comparison indicates elastic analysis Part 5 methods can improve the design from that of Part 4 over some, but not all, configurations within the study’s scope. The bounds of where the elastic analysis Part 5 methods benefit are identified. In the process of the study’s effort, numerous responses are identified and compared between design methodologies. The comparison is one of needed nozzle thickness for similar geometries. Behavior responses are shown from the range of configurations in the large simulation set created by the Part 5 method. For the Part 4 response, charts are shown that identify the required nozzle thickness based on the varying reinforcing limit logic employed in that method.

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Sreedharan, Sai Shrinivas, and Danesh K. Tafti. "Effect of Blowing Ratio on Syngas Flyash Particle Deposition on a Three-Row Leading Edge Film Cooling Geometry Using Large Eddy Simulations." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59326.

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A numerical study is performed to investigate deposition and erosion of Syngas ash in the leading edge region of a turbine vane. The leading edge of the vane is modeled as a symmetric semi-cylinder with a flat after body. Three rows of coolant holes located at stagnation and at ±21.3° from stagnation are simulated at blowing ratios of 0.5, 1.0, 1.5 and 2.0. Large Eddy Simulation (LES) is used to model the flow field of the coolant jet-mainstream interaction and syngas ash particles are modeled using a Lagrangian framework. Ash particle sizes of 5 and 7 micron are considered. Under the conditions of the current simulations, both ash particles have Stokes numbers less than unity of O(1) and hence are strongly affected by the flow and thermal field generated by the coolant interaction with the mainstream. Because of this, the stagnation coolant jets are quite successful in pushing the particles away from the surface and minimizing deposition and erosion in the stagnation region. Overall, about 10% of the 5 μm particles versus 20% of the 7 μm particles are deposited on the surface at B.R. = 0.5. An increase to B.R. = 2, increases deposition of the 5 micron particles to 14% while decreasing deposition of the 7 micron particles to 15%. Erosive ash particles of 5 μm size increase from 5% of the total to 10% as the blowing ratio increases from 0.5 to 2.0, whereas 7 μm erosive particles remain nearly constant at 15%. Overall, for particles of size 5 μm, there is a combined increase in deposition and erosive particles from 16% to 24% as the blowing ratio increases from 0.5 to 2.0. The 7 μm particles, on the other hand decrease from 35% to about 30% as the blowing ratio increases from 0.5 to 2.

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Chang, Zhiyong, Zezhong C. Chen, Jie Zhao, and Dinghua Zhang. "A Generic Approach to Modeling Geometry of Un-Deformed Chip by Mathematical Representing Envelopes of Swept Cutter in Five-Axis CNC Milling." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34135.

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To pursue high performance 5-axis CNC milling in industry, it is crucial to simulate each specific mill process in high fidelity beforehand, which should model the machined surfaces and predict the cutting forces in the process planning. However, the kernel technique, representation of the un-deformed chip geometry removed by cutter in 5-axis milling, is far from mature. Aiming to solve the problem, this paper presents a generic approach to representing un-deformed chip geometry mathematically in 5-axis CNC milling. The unique features of this research are: (1) the machine tool kinematics chain is investigated and a 5-axis CNC interpolation algorithm is adopted to establish the tool kinematics model, and (2) the closed-form equation of the un-deformed chip geometry representation is derived based on the machined shape being the envelope of a group of ellipses. This approach can model a machined surface with high accuracy and efficiently, and can be used to evaluate the machine surface quality and machining parameters. It can greatly promote the technique of high performance 5-axis CNC milling.

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Звіти організацій з теми "2.5 geometry"

Kirchhoff, Helmut, and Ziv Reich. Protection of the photosynthetic apparatus during desiccation in resurrection plants. United States Department of Agriculture, February 2014. http://dx.doi.org/10.32747/2014.7699861.bard.

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In this project, we studied the photosynthetic apparatus during dehydration and rehydration of the homoiochlorophyllous resurrection plant Craterostigmapumilum (retains most of the photosynthetic components during desiccation). Resurrection plants have the remarkable capability to withstand desiccation, being able to revive after prolonged severe water deficit in a few days upon rehydration. Homoiochlorophyllous resurrection plants are very efficient in protecting the photosynthetic machinery against damage by reactive oxygen production under drought. The main purpose of this BARD project was to unravel these largely unknown protection strategies for C. pumilum. In detail, the specific objectives were: (1) To determine the distribution and local organization of photosynthetic protein complexes and formation of inverted hexagonal phases within the thylakoid membranes at different dehydration/rehydration states. (2) To determine the 3D structure and characterize the geometry, topology, and mechanics of the thylakoid network at the different states. (3) Generation of molecular models for thylakoids at the different states and study the implications for diffusion within the thylakoid lumen. (4) Characterization of inter-system electron transport, quantum efficiencies, photosystem antenna sizes and distribution, NPQ, and photoinhibition at different hydration states. (5) Measuring the partition of photosynthetic reducing equivalents between the Calvin cycle, photorespiration, and the water-water cycle. At the beginning of the project, we decided to use C. pumilum instead of C. wilmsii because the former species was available from our collaborator Dr. Farrant. In addition to the original two dehydration states (40 relative water content=RWC and 5% RWC), we characterized a third state (15-20%) because some interesting changes occurs at this RWC. Furthermore, it was not possible to detect D1 protein levels by Western blot analysis because antibodies against other higher plants failed to detect D1 in C. pumilum. We developed growth conditions that allow reproducible generation of different dehydration and rehydration states for C. pumilum. Furthermore, advanced spectroscopy and microscopy for C. pumilum were established to obtain a detailed picture of structural and functional changes of the photosynthetic apparatus in different hydrated states. Main findings of our study are: 1. Anthocyan accumulation during desiccation alleviates the light pressure within the leaves (Fig. 1). 2. During desiccation, stomatal closure leads to drastic reductions in CO2 fixation and photorespiration. We could not identify alternative electron sinks as a solution to reduce ROS production. 3. On the supramolecular level, semicrystalline protein arrays were identified in thylakoid membranes in the desiccated state (see Fig. 3). On the electron transport level, a specific series of shut downs occur (summarized in Fig. 2). The main events include: Early shutdown of the ATPase activity, cessation of electron transport between cyt. bf complex and PSI (can reduce ROS formation at PSI); at higher dehydration levels uncoupling of LHCII from PSII and cessation of electron flow from PSII accompanied by crystal formation. The later could severe as a swift PSII reservoir during rehydration. The specific order of events in the course of dehydration and rehydration discovered in this project is indicative for regulated structural transitions specifically realized in resurrection plants. This detailed knowledge can serve as an interesting starting point for rationale genetic engineering of drought-tolerant crops.

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