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Relevant bibliographies by topics / String tree amplitude theory

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Academic literature on the topic 'String tree amplitude theory'

Author: Grafiati

Published: 4 June 2021

Last updated: 16 February 2022

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Journal articles on the topic "String tree amplitude theory"

1

MARUI, MIHO, ICHIRO ODA, and AKIO SUGAMOTO. "A NOTE ON STRING AMPLITUDES AT HIGH ENERGY LIMIT." Modern Physics Letters A 04, no. 22 (October 30, 1989): 2177–83. http://dx.doi.org/10.1142/s0217732389002446.

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LI, MIAO. "SOME REMARKS ON TACHYON ACTION IN 2D STRING THEORY." Modern Physics Letters A 08, no. 26 (August 30, 1993): 2481–89. http://dx.doi.org/10.1142/s0217732393002804.

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We discuss the effective action of tachyon in the two-dimensional string theory at tree level. We show that even starting from the cubic terms the action is nonlocal and the usually assumed simplest cubic term does not give the correct amplitude. Four-point 1PI terms are also discussed.

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SATHIAPALAN, B. "LOOP VARIABLES AND GAUGE INVARIANCE IN CLOSED BOSONIC STRING THEORY." Modern Physics Letters A 19, no. 38 (December 14, 2004): 2857–70. http://dx.doi.org/10.1142/s0217732304015713.

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We extend an earlier proposal for a gauge-invariant description of off-shell open strings (at tree level), using loop variables, to off-shell closed strings (at tree level). The basic idea is to describe the closed string amplitudes as a product of two open string amplitudes (using the technique of Kawai, Lewellen and Tye). The loop variable techniques that were used earlier for open strings can be applied here mutatis mutandis. It is a proposal for a theory whose on-shell amplitudes coincide with those of the closed bosonic string in 26 dimensions. It is also gauge-invariant off-shell. As was the case with the open string, the interacting closed string looks like a free closed string thickened to a band.

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Dolan, Louise, and Peter Goddard. "Gluon tree amplitudes in open twistor string theory." Journal of High Energy Physics 2009, no. 12 (December 9, 2009): 032. http://dx.doi.org/10.1088/1126-6708/2009/12/032.

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NATSUUME, MAKOTO. "ZERO MODE DIVERGENCE PROBLEM IN STRING THEORY." Modern Physics Letters A 09, no. 23 (July 30, 1994): 2113–22. http://dx.doi.org/10.1142/s0217732394001970.

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For 2D string theory, the perturbative S-matrices are not well-defined due to a zero mode divergence. Although there exist formal procedures to make the integral convergent, their physical meanings are not clear. We describe a method to obtain finite S-matrices physically to justify the formal schemes. The scheme uses asymptotic states by wave packets which fall faster than exponentials. It is shown that the scheme gives well-defined S-matrices and justifies the formal shifted Virasoro-Shapiro amplitude for simple processes. The tree-level unitarity for these processes is also shown. We point out a problem in this scheme.

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Dolan, Louise, and Peter Goddard. "Tree and loop amplitudes in open twistor string theory." Journal of High Energy Physics 2007, no. 06 (June 4, 2007): 005. http://dx.doi.org/10.1088/1126-6708/2007/06/005.

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Dolan, Louise, and Jay N. Ihry. "Conformal supergravity tree amplitudes from open twistor string theory." Nuclear Physics B 819, no. 3 (October 2009): 375–99. http://dx.doi.org/10.1016/j.nuclphysb.2009.04.003.

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HADASZ, LESZEK, and ZBIGNIEW JASKÓLSKI. "NONCRITICAL STRING LIOUVILLE THEORY AND GEOMETRIC BOOTSTRAP HYPOTHESIS." International Journal of Modern Physics A 19, no. 13 (May 20, 2004): 2079–93. http://dx.doi.org/10.1142/s0217751x04018427.

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The applications of the existing Liouville theories for the description of the longitudinal dynamics of noncritical Nambu–Goto string are analyzed. We show that the recently developed DOZZ solution to the Liouville theory leads to the cut singularities in tree string amplitudes. We propose a new version of the Polyakov geometric approach to Liouville theory and formulate its basic consistency condition — the geometric bootstrap equation. Also in this approach the tree amplitudes develop cut singularities.

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SATHIAPALAN, B. "HOLOMORPHIC FACTORIZATION AND RENORMALIZATION GROUP IN CLOSED STRING THEORY." Modern Physics Letters A 20, no. 15 (May 20, 2005): 1161–76. http://dx.doi.org/10.1142/s0217732305017226.

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The prescription of Kawai, Lewellen and Tye for writing closed string tree amplitudes as sums of products of open string tree amplitudes, is applied to the worldsheet renormalization group equation. The main point is that regularization of the Minkowski (rather than Euclidean) worldsheet theory allows factorization into left-moving and right-moving sectors to be maintained. Explicit calculations are done for the tachyon and the (gauge fixed) graviton.

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UKEGAWA, AKINOBU. "OFF-SHELL TREE AMPLITUDES IN HIKKO’S CLOSED STRING FIELD THEORY." International Journal of Modern Physics A 07, no. 20 (August 10, 1992): 5019–26. http://dx.doi.org/10.1142/s0217751x92002283.

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Dissertations / Theses on the topic "String tree amplitude theory"

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Mavromatos, N. E. "Aspects of the low energy limit of string theories." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379937.

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Paton, John. "Tree-Level N-Point Amplitudes in String Theory." Thesis, Uppsala universitet, Teoretisk fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296369.

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This thesis reviews the method of Mafra, Schlotterer, and Stieberger (2011) for computing the full colour ordered N-point open superstring amplitude using the Pure Spinor formalism. We introduce relevant elements of super Yang-Mills theory and examine the basics of the Pure Spinor formalism, with a focus on tools for amplitude computation. We then define a series of objects with increasingly useful BRST transformation properties, which greatly simplify the calculations, and show how these properties can be determined using a diagrammatic method. Finally, we use the explicit four- and five-point amplitude computations as stepping stones to compute the general N-point amplitude, which factors into a set of kinematic integrals multiplying SYM subamplitudes.

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Tourkine, Piotr. "Results in perturbative quantum supergravity from string theory." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066295/document.

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Les théories de supergravité sont des extensions supersymmetriques de la relativité générale (RG) d'Einstein. Leur comportement ultraviolet (UV) est meilleur que celui de la RG car les contributions bosoniques et fermioniques se compensent dans les diagrammes en boucles. La supergravité maximale a le meilleur comportement UV, toutefois les prédictions les plus précises venant aussi bien de la théorie des champs que de la théorie des cordes indiquent que la théorie devrait elle aussi souffrir de divergences UV, à partir de 7 boucles. Cette question ouverte constitue un cadre dans lequel peut être problématisés ma thèse. En général, l'approche que j'ai suivie consiste à étudier les amplitudes de diffusion en théorie des cordes dans la limite ou la longueur de la corde devient nulle; on s'attend ainsi à retrouver les amplitudes de diffusion de supergravité. Curieusement, on sait très peu de choses sur cette limite au délà d'une boucle. Une part importante de mon travail thèse a consisté à développer des outils mathématiques basés sur la géométrie tropicale pour décrire cette limite en genre deux et au délà. Afin de tester la précision des prédiction de la théorie des cordes, dans ma thèse j'ai aussi travaillé sur le comportement UV des théories de supergravité demi-maximale. Nous avons montré un théorème de non-renormalisation qui expliqué l'absence de divgerence à 3 boucles et en prédit une à 4 boucles. Enfin je me suis intéressé aux techniques utilisées en théorie des champs pour calculer ces amplitudes à haut nombre de boucles en théorie des champs, et notament à la "double copie BCJ", dont avons proposé la première analyse à une boucle depuis la théorie des cordes
Supergravity theories are supersymmetric extensions of General Relativity (GR). They have a better ultraviolet (UV) behavior than GR, due to cancellations between bosons and fermions in loop diagrams. Maximal supergravity is a candidate for a UV finite point-like theory of quantum gravity. Nowadays, the most advanced understanding coming from field theory and string theory indicate that the theory should not be UV finite, and that the first UV divergences should appear at the 7-loop order. This open question constitutes a background in which my PhD thesis can be problematized.In this thesis, our approach consists in using string theory scattering amplitudes and study their point-like limit, in which supergravity amplitudes are expected to be recovered. Very little is known beyond one loop on this limit and in this manuscript I describe first how a recent field of mathematics, tropical geometry, may be used in this process, and mention some applications and open issues.Another way to cross-check the predictions of string theory on the UV behavior of maximal supergravity consists in performing the same analysis in theories of reduced supersymmetry.I discuss the case of half-maximal supergravity theories, and show a non-renormalization theorem in heterotic string which explains the vanishing of the 3-loop divergence of this theory and predicts a 4-loop divergence.The last aspect of my work is focused on a string theoretic understanding on the techniques used in field theory to compute higher loop amplitudes. I describe the first analysis of the so called BCJ double copy construction at one-loop from string theory, and partly explain the origin of the BCJ prescription

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Mirza, Behrouz. "On the transition between crystalline and gravitational phases in two dimensional theories with matter fields." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318930.

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Söderberg, Alexander. "Browsing the Web of Amplitudes." Thesis, Uppsala universitet, Teoretisk fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-309989.

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We begin by studying field-theory amplitude relations such as the Kleiss-Kuijf, Bern-Carrasco-Johansson, Kawai-Lewellen-Tye and the double copy construction, which are important ingredients in this thesis. Going beyond the field-theory limit we study how the gauge-sector of the heterotic string relates to type I amplitudes through the single valued projection of multiple zeta values. At low energy and for a U(1) gauge group (a single brane) the type I amplitudes are generated by the Born-Infeld action, whereas the corresponding heterotic amplitudes vanish in this limit. As a simple exercise we study Yang-Mills theory deformed by a $F^4$ operator, which is the first correction induced by the Born-Infeld action. This exercise is then generalized by considering the four- and six-point amplitudes in Tseytlin's proposal for a non-Abelian Born-Infeld action. Comparing these amplitudes with those found in type I and heterotic string theory we attempt to gain more insight about the non-Abelian Born-Infeld action.

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Hsu, Tai C. "Walking tree methods for biological string matching." Thesis, 2003. http://hdl.handle.net/1957/32486.

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Cavener, Jeffrey Douglas. "Visualization, implementation, and application of the Walking Tree heuristics for biological string matching." Thesis, 1997. http://hdl.handle.net/1957/33688.

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Biologists need tools to see the structural relationships encoded in biological sequences (strings). The Walking Tree heuristics calculate some of these relationships. I have designed and implemented graphic presentations which allow the biologist (user) to see these relations. This thesis contains background information on the biological sequences and some background on the Walking Tree heuristics. I demonstrate my methods by showing a visual matching of mitochondrial genomes. I also show matchings based on amino acids and on hydrophobicity. I also show how the parameters of the visualization can be varied to produce more useful pictures. I implemented a parallel version of the Walking Tree heuristic and used it to produce a phylogenetic tree for picornaviruses. I also implemented several user interfaces. These programs are available on my WWW page which allows a user to produce a picture of a matching by giving the sequences in Gen Bank format and by making a few mouse clicks.
Graduation date: 1998

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Books on the topic "String tree amplitude theory"

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Cull, Paul. Walking tree heuristics for string matching and gene location. Corvallis, OR: Oregon State University, Dept. of Computer Science, 1997.

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Hsu, Tai C. Fast walking tree method via recurrence reduction for biological string alignment. [Corvallis, OR: Oregon State University, Dept. of Computer Science, 2002.

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Cavener, Jeffrey Douglas. Visualization, implementation, and application of the Walking Tree heuristics for biological string matching. 1997.

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Book chapters on the topic "String tree amplitude theory"

1

Erbin, Harold. "Amplitude Factorization and Feynman Diagrams." In String Field Theory, 285–308. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-65321-7_14.

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Garrett, Steven L. "String Theory." In Understanding Acoustics, 133–78. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_3.

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Abstract The vibrating string has been employed by nearly every human culture to create musical instruments. Although the musical application has attracted the attention of mathematical and scientific analysts since the time of Pythagoras (570 BC–495 BC), we will study the string primarily because its vibrations are easy to visualize and string vibrations introduce concepts and techniques that will recur throughout our study of the vibration and the acoustics of continua. In this chapter, we will develop continuous mathematical functions of position and time that describe the shape of the entire string. The amplitude of such functions will describe the transverse displacement from equilibrium, y(x, t), at all positions along the string. The importance of boundary conditions at the ends of strings will be emphasized, and techniques to accommodate both ideal and “imperfect” boundary conditions will be introduced. Solutions that result in all parts of the string oscillating at the same frequency which satisfy the boundary conditions are called normal modes, and the calculation of those normal mode frequencies will be a focus of this chapter.

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Phong, Duong. "The one-loop graviton scattering amplitude in string theory." In CRM Proceedings and Lecture Notes, 357–72. Providence, Rhode Island: American Mathematical Society, 1997. http://dx.doi.org/10.1090/crmp/011/18.

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Engelfriet, Joost, and Sebastian Maneth. "Hierarchies of String Languages Generated by Deterministic Tree Transducers." In Developments in Language Theory, 228–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-46011-x_19.

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"Tree-level amplitudes." In String Theory, 166–205. Cambridge University Press, 1998. http://dx.doi.org/10.1017/cbo9780511816079.009.

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"Treeing Property In Polypropylene Under Various Temperature and Electrical Field." In Electrical Insulation Breakdown and Its Theory, Process, and Prevention, 181–218. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-8885-6.ch007.

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Polypropylene (PP) has no cross-linking process and environmentally friendly properties and is considered to be a replacement for cross-linked polyethylene (xlpe) for high voltage direct current (HVDC) cable insulation. High-voltage DC cable systems generate repetitive pulse voltages during operation and may encounter different temperature environmental challenges. This chapter discusses the effects of pulse amplitude and frequency on PP trees at different temperatures. A higher pulse frequency accelerates the propagation of the tree. Higher amplitudes accelerate tree growth and fractal dimensions. In addition, the effects of DC voltage, pulse voltage, and pulse frequency on the tree characteristics of PP at DC voltage and pulse combination voltage are also studied.

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Conference papers on the topic "String tree amplitude theory"

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Nielsen, Holger Bech, and Masao Ninomiya. "An Object Model of String Field Theory and Derivation of Veneziano Amplitude." In Corfu Summer Institute 2016 "School and Workshops on Elementary Particle Physics and Gravity". Trieste, Italy: Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.292.0134.

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Gahan, Kevan W. F., and John P. Parmigiani. "Monotonic and Fatigue Testing of Polymer and Composite Materials Used in Heavy Duty Trucks." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11680.

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Abstract Improved material models for engineered polymer and composite materials including both monotonic and fatigue characteristics are necessary for creating more accurate digital simulations for heavy duty trucks. Unlike steel and other alloys that are commonly included in truck designs, these advanced polymer materials do not have pre-existing fatigue characteristic data. Additionally, there are no individual standard test procedures that can be commonly cited and followed during a research program. These materials are found in hoods, dashboards, body panels and splash shields of trucks, and are subject to cyclic loading conditions at various amplitudes and durations throughout the entire use or “duty cycle” of the vehicle. The applied loads vary between truck models, as some trucks will be used for vocational purposes and others will remain on the highway. This paper describes the testing of isotropic non-reinforced, and anisotropic glass-fiber-reinforced polymers and the subsequent calculation of the monotonic and fatigue properties that are needed to describe their behavior under various loading conditions. Material characteristics are measured using a series of constant amplitude strain-controlled fatigue tests that follow standard practices from ASTM D638 (Standard Test Method for Tensile Properties of Plastics), ASTM E606 (Standard Practice for Strain-Controlled Fatigue Testing) methods, and SAE J1099 (Technical Report on Low Cycle Fatigue Properties of Ferrous and Non-Ferrous Materials). The ASTM D638 Type 1 coupon geometry is used for all materials, with a varied sample thickness and length. An axial extensometer is incorporated to measure strain data through the duration of all tests, and an anti-buckling fixture is installed during cyclic tests to eliminate any bending in the specimen during the compressive portion of the fully-reversed waveform. A transverse extensometer is also installed on the gauge length of the material coupons to measure instantaneous cross-sectional area as well as Poisson’s ratio during monotonic testing. The data collected through the monotonic testing procedure is used to calculate Young’s Modulus, Poisson’s ratio, ultimate tensile strength, elongation (% strain), yield strength and strain, and true fracture strength and strain. The fatigue testing procedure yields data that can be used to calculate the fatigue strength coefficient (σf′), fatigue strength exponent (b), fatigue ductility coefficient (εf′), and fatigue ductility exponent (c). These parameters provide accurate stress-strain, cyclic stress-strain, and strain-life curves for the materials in question. A method will also be suggested for calculating the stress-life fatigue parameters, stress range intercept and slope, from the strain-controlled data. Furthermore, mold-flow analysis is applied to predict general orientation of the reinforcement fibers induced by the direction of material flow as a part is injection-molded. The calculated monotonic and fatigue parameters in conjunction with mold-flow analysis can immediately be applied within digital s imulations, allowing improved accuracy in life-expectancy estimations for truck parts.

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Lübbe, Bertold, Jens Aschenbruck, Oliver Pütz, and Mira Theidel. "Design and Validation of a Large Steam Turbine End-Stage Blade to Meet Current and Future Market Demands." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59315.

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Abstract To meet today’s and future market needs, large end-stage blades are obliged to fulfill high flexibility regarding the operational range and high efficiency goals while being prepared for daily start-stop cycles. The end-stage total efficiency can be maximized by enlarging the steam turbine exhaust area and thereby reducing the exhaust losses. Therefore, a new Low Pressure (LP) backend featuring an increased freestanding 41″ steel blade has been developed and is presented here, which is optimized for maximum efficiency over a wide range of operation conditions. To allow for such a large steel-blade to operate at 60Hz rotational speed and to meet the daily cycling demand, various aspects of the blade design were optimized. A new high strength blade steel was developed (Teuber [1]), which gives the designer freedom for aerodynamical optimizations, while keeping the mechanical utilization within the predefined, allowable limits. To maximize the cycling capability, a new fir tree root was developed which minimizes the static as well as the dynamic loading. To verify the success of the new fir-tree root design and to verify the natural frequencies for the relevant modes, an extensive validation measurement campaign was setup with a full-scale blade row in a spin-pit. Here, the airfoil, root and steeple of the end-stage blade were equipped with strain gauges. Additionally, the blade row was monitored using tip-timing sensors. The results of this validation measurement campaign are presented in this paper. They show a close agreement between the design calculations and the measured static strains and vibration responses in terms of natural frequencies as well as displacement and strain amplitudes. Additionally, a test turbine has been set-up featuring a direct scaling of the new LP backend with the new high strength steel and a pre-stage to simulate realistic operation conditions over the complete operation range. The blade performance was tested up to high mass-flows, condenser pressures of up to 300 mbar and at varying load points covering all potential load points from extreme part load to full load with minimal and maximal condenser pressure. Strain gauges as well as tip-timing are used to measure the vibration response of the end-stage blade during the measurement campaign. The results presented here show, that throughout the complete measurement campaign the blade experienced minimal excitation which led to vibration levels that allowed unrestricted operation in the complete, tested operation range. In summary this paper shows the main design features of a large full-speed freestanding end-stage blade and the validation measures that were performed to ensure that the design targets and the market requirements are fully met.

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Chen, Li-Qun. "Principal Parametric Resonance of Axially Accelerating Viscoelastic Strings." In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84435.

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The steady-state transverse responses and the stability of an axially accelerating viscoelastic string are investigated. The governing equation is derived from the Eulerian equation of motion of a continuum, which leads to the Mote model for transverse motion. The Kirchhoff model is derived from the Mote model by replacing the tension with the averaged tension over the string. The method of multiple scales is applied to the two models in the case of principal parametric resonance. Closed-form expressions of the amplitudes and the existence conditions of steady-state periodical responses are presented. The Lyapunov linearized stability theory is employed to demonstrate that the first (second) nontrivial steady-state response is always stable (unstable). Numerical calculations show that the two models are qualitatively the same, but quantitatively different. Numerical results are also presented to highlight the effects of the mean axial speed, the axial speed fluctuation amplitude, and the viscoelastic parameters.

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Vieira, Daniel P., Edgard B. Malta, Rafael A. Watai, Rodolfo T. Gonçalves, André L. C. Fujarra, Kazuo Nishimoto, and Allan C. Oliveira. "MPSO Design: Part 1 — Wave Excitation Forces and Moments." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83997.

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The MPSO is characterized by the use of hydrodynamics appendages, such as moonpool, beach and skirts, which improve the hydrodynamic behavior of the unit in waves. This type of platform may be designed for different offshore scenarios as, for example: the possibility of oil and gas storage, dry tree completion system and the use of steel catenary risers (SCR). An optimization procedure to choose the geometric dimensions of the MPSO becomes important in order to achieve the optimum hydrodynamic behavior to operate in harsh environmental conditions for each scenario. The optimization procedure might be useful in the preliminary design phases to reduce the verification time of the solution evaluated with model tests; for that reason it is necessary to create a database with experimental results to make the optimization procedure possible. The main idea of the study is to carry out an extensive experimental model test aimed at obtaining the parameters not well predicted using numerical codes. With this intent, the work is subdivided into three parts: Part 1 – Wave Excitation Forces and Moments; Part 2 – Damping and Added Mass Forces and Part 3 – Optimization Process. Results will be presented in different papers. The first one presents the experimental results for captive tests, the second one the experimental results for forced oscillation tests and the last one the methodology to use the experimental results as input in an optimization tool. The first paper presents the methodology in which nondimensional variables based on MPSO geometric characteristics were defined. These variables were related to a fixed moonpool diameter and they were determined in terms of four geometric dimensions: external diameter; height and diameter of the beach and platform draft. As a consequence, 21 different MPSO model geometries could be defined and experimentally tested in order to obtain the wave excitation forces and moments in 6 DOF. The experiments included transient waves so as to better understand the hydrodynamic behavior of the hull, such as, the response amplitude operator (RAO), cancelation points, the beach/bottom/moonpool effects for the different dimensions. The wave forces and moments obtained experimentally were compared to the results of a numerical code based on potential wave theory.

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