Bibliografias temáticas / String models

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Literatura científica selecionada sobre o tema "String models"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 1 de agosto de 2024

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Artigos de revistas sobre o assunto "String models"

Gustafson, Gösta. "String models". Nuclear Physics A 566 (janeiro de 1994): 233–44. http://dx.doi.org/10.1016/0375-9474(94)90629-7.

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Boulware, David G., e S. Deser. "String-Generated Gravity Models". Physical Review Letters 55, n.º 24 (9 de dezembro de 1985): 2656–60. http://dx.doi.org/10.1103/physrevlett.55.2656.

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Lawrence, Albion, e John McGreevy. "D-terms and D-strings in open string models". Journal of High Energy Physics 2004, n.º 10 (23 de outubro de 2004): 056. http://dx.doi.org/10.1088/1126-6708/2004/10/056.

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RANDJBAR-DAEMI, S., ABDUS SALAM e J. A. STRATHDEE. "σ-MODELS AND STRING THEORIES". International Journal of Modern Physics A 02, n.º 03 (junho de 1987): 667–93. http://dx.doi.org/10.1142/s0217751x87000247.

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The propagation of closed bosonic strings interacting with background gravitational and dilaton fields is reviewed. The string is treated as a quantum field theory on a compact 2-dimensional manifold. The question is posed as to how the conditions for the vanishing trace anomaly and the ensuing background field equations may depend on global features of the manifold. It is shown that to the leading order in σ-model perturbation theory the string loop effects do not modify the gravitational and the dilaton field equations. However for the purely bosonic strings new terms involving the modular parameter of the world sheet are induced by quantum effects which can be absorbed into a re-definition of the background fields. We also discuss some aspects of several regularization schemes such as dimensional, Pauli-Villars and the proper-time cut off in an appendix.

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Faraggi, A. E., E. Manno e C. Timirgaziu. "Minimal standard heterotic string models". European Physical Journal C 50, n.º 3 (6 de março de 2007): 701–10. http://dx.doi.org/10.1140/epjc/s10052-007-0243-5.

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Nepomechie, Rafael I. "String models with twisted currents". Physical Review D 34, n.º 4 (15 de agosto de 1986): 1129–35. http://dx.doi.org/10.1103/physrevd.34.1129.

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Bergman, Oren, e Charles B. Thorn. "String bit models for superstring". Physical Review D 52, n.º 10 (15 de novembro de 1995): 5980–96. http://dx.doi.org/10.1103/physrevd.52.5980.

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Danilov, G. S., e L. N. Lipatov. "BFKL pomeron in string models". Nuclear Physics B 754, n.º 1-2 (outubro de 2006): 187–232. http://dx.doi.org/10.1016/j.nuclphysb.2006.07.017.

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Moss de Oliveira, S., P. M. C. de Oliveira e D. Stauffer. "Bit-string models for parasex". Physica A: Statistical Mechanics and its Applications 322 (maio de 2003): 521–30. http://dx.doi.org/10.1016/s0378-4371(02)01916-7.

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Constantin, Andrei, Yang-Hui He e Andre Lukas. "Counting string theory standard models". Physics Letters B 792 (maio de 2019): 258–62. http://dx.doi.org/10.1016/j.physletb.2019.03.048.

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Teses / dissertações sobre o assunto "String models"

García, Pulido Ana Lucía. "Models and string topology". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56787/.

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This thesis concerns the study of string topology, a relatively new branch of algebraic topology. We begin with a survey of the background of string topology. In particular, this includes a summary of the papers [4] by Chas and Sulivan, [15] by Jones and [5] by Cohen and Jones that provide the background for the original work of this thesis. We then proceed to give a new e cient technique to do systematic computations of the full structure of the string topology for a large family of manifolds. For this, we rst use the results of Jones [15] and Cohen and Jones [5] to reduce the problem to calculating Hochschild homology and cohomology. Secondly, we use the concept of models to compute Hochschild homology and cohomology and obtain some further Hochschild structure. Thus, most of this work is devoted to developing this technique for calculating Hochschild homology and cohomology via models. This research contributes to the area by providing the rst general and systematic method of computing the full structure of string topology. In addition, we give multiple, transparent examples of our new theory.

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Godazgar, Mohammad Hadi. "Dualities in string theory". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610466.

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Lambert, Neil. "Massive sigma models and string solitons". Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627529.

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Boyce, Michael M. (Michael MacField) Carleton University Dissertation Physics. "String inspired QCD and E6 models". Ottawa, 1996.

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Bianchi, Lorenzo. "Perturbation theory for string sigma models". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17439.

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In dieser Arbeit untersuchen wir Quanten-Aspekte des Green-Schwarz Superstrings in verschiedenen AdS-Hintergründen, die für die AdS/CFT Korrespondenz von Bedeutung sind, und geben einige Beispiele für perturbative Rechnungen in den entsprechenden integrablen Sigma-Modellen. Wir beginnen mit einer detaillierten Darstellung der Konstruktion der Wirkung des Typ-IIB-Superstrings auf dem AdS5 x S5-Hintergrund, die durch eine Supercoset-Sigma-Modell definiert wird, und zeigen die Grenzen dieser Herangehensweise für Hintergründe auf, die in niedrig-dimensionalen Beispielen der Eich/Gravitations-Dualität von Interesse sind. Daraufhin betrachten wir die Entwicklung um das BMN-Vakuum und die S-Matrix für die Streuung von Weltflächen-Anregungen. Um ihre Elemente effizient auszuwerten, entwickeln wir eine auf Unitarität basierende Methode für allgemeine massive, zweidimensionale Feldtheorien. Weiterhin betrachten wir den AdS-Lichtkegel eichfixierten String in AdS4 x CP3 in einer Entwicklung um das "null-cusp"-Vakuum. Die freie Energie dieses Modells hängt zusammen mit der anomalen Cusp-Dimension der Eichtheorie. Wir berechnen Korrekturen zur Zustandssumme des Superstring-Modells und leiten somit die anomale Cusp-Dimension der ABJM-Theorie bei starker Kopplung bis zur Zweischleifen-Ordnung her. Schlie\sslich berechnen wir auf Einschleifen-Ebene die Dispersionsrelation von Anregungen um das GKP-Vakuum. Unsere erfolgreiche Anwendung von auf Unitarität basierenden Cut-Techniken auf verschiedene Beispiele stützt die Vermutung, dass die S-Matrizen zweidimensionaler, integrabler Feldtheorien cut-konstruierbar sind. Weiterhin liefern unsere Ergebnisse wertvolle Daten, die die Konsistenz der String-Wirkung auf Quanten-Niveau belegen und stellen nicht-triviale stringente Tests der Quanten-Integrabilität der untersuchten Modelle dar.
In this thesis we investigate quantum aspects of the Green-Schwarz superstring in various AdS backgrounds relevant for the AdS/CFT correspondence, providing several examples of perturbative computations in the corresponding integrable sigma-models. We start by reviewing in details the construction of the type IIB superstring action in AdS5 x S5 background defined as a supercoset sigma model, pointing out the limits of this procedure for backgrounds interesting in lower-dimensional examples of the gauge/gravity duality. We then consider the expansion about the BMN vacuum and the S-matrix for the scattering of worldsheet excitations. To evaluate its elements efficiently we develop a unitarity-based method for general massive two-dimensional field theories. We also analyze the AdS light-cone gauge fixed string in AdS4 x CP3 expanded around a “null cusp” vacuum. The free energy of this model is related to the cusp anomalous dimension of the gauge theory and, indirectly, to a non-trivial effective coupling entering all integrability-based calculations in AdS4/CFT3. We calculate corrections to the superstring partition function of the model, thus deriving the cusp anomalous dimension of ABJM theory at strong coupling up to two-loop order and giving support to a recent conjecture. Finally, we calculate at one-loop the dispersion relation of excitations about the GKP vacuum. Our successful application of unitarity-cut techniques on several examples supports the conjecture that S-matrices of two-dimensional integrable field theories are cut-constructible. Furthermore, our results provide valuable data in support of the quantum consistency of the string actions and furnish non-trivial stringent tests for the quantum integrability of the analyzed models.

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Bernardo, Heliudson de Oliveira. "Cosmological models from string theory setups /". São Paulo, 2019. http://hdl.handle.net/11449/183612.

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Orientador: Horatiu Nastase
Resumo: Nesta tese, discutimos três modelos cosmológicos que são baseados direta ou indiretamente em ideias advindas de teoria das cordas. Depois de uma revisão geral de cosmologia em teoria das cordas, um resumo de cosmologia e teoria das cordas é apresentado, com ênfase nos conceitos fundamentais e teóricos. Então descrevemos como o acoplamento camaleônico pode potencialmente afetar as predições de inflação cósmica com campo único, com tratamento cuidadoso dos modos de perturbação cosmológica adiabáticos e de entropia. Além disso uma nova abordagem para a dualidade-T em soluções cosmológicas de supergravidade bosônica é discutida no contexto de teoria dupla de campos. Por fim, propomos uma nova prescrição para o mapa holográfico em cosmologia que pode ser usado para conectar modelos fundamentais de cosmologia holográfica com outras abordagens fenomenológicas.
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Keyserlingk, Curt William Von. "String-net models in condensed matter systems". Thesis, University of Oxford, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669743.

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Berndsen, Aaron. "String theoretic models of the early universe". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18674.

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This thesis comprises several manuscripts, each exploring aspects of the dynamics of the early Universe. The foundations of the work presented lies in the realm of cosmology, but draws heavily on string theory as a source of guidance. The thesis commences with a motivation for the research and provides an introduction to the contemporary views of Cosmology: following a historical perspective of cosmology, we motivate the inflationary paradigm of Big Bang Cosmology, and introduce several world-views promoted by string theory. The string-motivated models will address shortcomings of cosmologies based on General Relativity and the Standard Model, and will provide a comprehensive, coherent description of the early Universe that is expected to transition to our observed Universe. Two possibilities presented here include String Gas Cosmology (SGC) and the Brane World scenario. We provide an introduction to these two constructions, and subsequently report on the possibility of simultaneously stabilizing the dilaton and moduli fields in SGC stabilization models, a mechanism to solve the overshoot problem of racetrack inflation, and explore the possibility of long-lived relics in warped reheating.
Cette th\èse explore la physique du jeune univers. Nous utilisons la th\'eorie des cordes pour nous aider \à comprendre l'\'epoque pr\'ec\'edant la nucl\'eosynth\èse. Deux manuscrits sont present\'es: un concernant la cosmologie de gaz de cordes (string gas cosmology, SGC), et un concernant le sc\'enario d'un univers membrane (brane world, BW). Nous pla\cons des contraintes sur la stabilization du moduli et du dilaton dans la construction SGC. Puis, nous \'etudions l\'epoque du r\'echauffement de l'univers dans la construction BW, et nous pla\c{c}ons des contraintes sur les param\ètres fundamentaux de la th\'eorie des cordes.

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Panvel, Jal. "Exact string backgrounds and gauged WZW models". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241464.

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Stepanchuk, Andrej. "Aspects of integrability in string sigma-models". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28904.

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The recent success in applying integrability-based methods to study examples of gauge/gravity dualities in highly (super)symmetric settings motivates the question of whether such methods can be carried over to more physical and less symmetric cases. In this thesis we consider two such examples of string sigma-models, which interpolate between integrable or solvable limits. First we consider classical string motion on curved p-brane backgrounds for which the sigma-model interpolates between the integrable flat space and AdS(k)xS(k) coset or WZW sigma-models. We find that while the equations for particle (i.e. geodesic) motion are integrable in these backgrounds, the equations for extended string motion are not. The second example we consider is string theory on AdS3xS3xT4 with mixed Ramond-Ramond (R-R) and Neveu-Schwarz-Neveu-Schwarz (NS-NS) 3-form fluxes, which interpolates between the integrable pure R-R and the pure NS-NS theory that can be solved using CFT methods. The dispersion relation and S-matrix for world-sheet excitations, which are the essential ingredients in solving for the string spectrum, are only partially fixed by integrability and symmetry arguments. By constructing the mixed flux generalisation of the dyonic giant magnon soliton, which we show can be interpreted as a bound-state of excitations, we determine the dispersion relation for massive excitations. We also construct the mixed flux generalisation of the folded string on AdS3xS1 and show that, at leading order in large angular momentum on AdS3, its energy is given by the pure R-R expression with the string tension rescaled by the R-R flux coefficient. Further, we derive the bound-state S-matrix and its 1-loop correction by considering the scattering of dyonic giant magnons and plane waves. From this we deduce the semiclassical and 1-loop dressing phases in the massive sector S-matrix, which we find to agree with recent proposals.

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Livros sobre o assunto "String models"

Lüst, D. Lectures on string theory. Berlin: Springer-Verlag, 1989.

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Lüst, D. Lectures on string theory. Berlin: Springer-Verlag, 1989.

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(Angel), Uranga A., ed. String theory and particle physics: An introduction to string phenomenology. Cambridge: Cambridge University Press, 2012.

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Neil, Turok, Fermi National Accelerator Laboratory e United States. National Aeronautics and Space Administration., eds. Evolution of cosmic string networks. Batavia, IL: Fermi National Accelerator Laboratory, 1989.

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McMahon, David. String Theory Demystified. New York: McGraw-Hill, 2008.

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Lars, Brink. Principles of string theory. New York: Plenum, 1988.

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Polchinski, Joseph Gerard. String theory. Cambridge, UK: Cambridge University Press, 1998.

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Michael, Dine, ed. String theory in four dimensions. Amsterdam: North Holland, 1988.

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1942-, Dita P., Georgescu V. 1947-, Institutul Central de Fizică (Romania) e Summer School on Conformal Invariance and String Theory (1987 : Poiana Brașov, Romania), eds. Conformal invariance and string theory. New York: Academic Press, 1989.

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N, Balogh Ferenc, ed. String theory research progress. Hauppauge, N.Y: Nova Science Publishers, 2007.

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Capítulos de livros sobre o assunto "String models"

Grosse, Harald. "String Models". In Models in Statistical Physics and Quantum Field Theory, 101–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83504-9_5.

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Manca, Vincenzo. "String Models and String Theories". In Formal Languages and Applications, 439–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-39886-8_23.

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Erfle, Stephen. "Double Jump Models". In Electronic String Art, 211–24. Boca Raton: A K Peters/CRC Press, 2024. http://dx.doi.org/10.1201/9781003402633-19.

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Erfle, Stephen. "Larger Jump Set Models". In Electronic String Art, 234–47. Boca Raton: A K Peters/CRC Press, 2024. http://dx.doi.org/10.1201/9781003402633-21.

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Marshakov, A. "String theory and classical integrable systems". In Integrable Models and Strings, 194–220. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/3-540-58453-6_11.

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Balasubramanian, Niranjan, e James Allan. "Syntactic Query Models for Restatement Retrieval". In String Processing and Information Retrieval, 143–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03784-9_14.

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Dupret, Georges. "Discounted Cumulative Gain and User Decision Models". In String Processing and Information Retrieval, 2–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-24583-1_2.

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Morozov, Alexei. "Challenges of Matrix Models". In String Theory: From Gauge Interactions to Cosmology, 129–62. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-3733-3_6.

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Antoniadis, Ignatios. "Physics Of Low Scale String Models". In Progress in String, Field and Particle Theory, 25–74. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0211-0_2.

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Sagnotti, Augusto. "Open-String Models with Broken Supersymmetry". In Statistical Field Theories, 171–84. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0514-2_16.

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Trabalhos de conferências sobre o assunto "String models"

Smolin, Lee. "Matrix models as hidden variables theories". In STRING THEORY; 10th Tohwa University International Symposium on String Theory. AIP, 2002. http://dx.doi.org/10.1063/1.1454379.

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Kawai, Hikaru. "Constructing new types of matrix models". In STRING THEORY; 10th Tohwa University International Symposium on String Theory. AIP, 2002. http://dx.doi.org/10.1063/1.1454364.

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KING, S. F. "STRING INSPIRED NEUTRINO MASS MODELS". In Proceedings of the First International Conference. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812704917_0026.

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Raby, Stuart. "Three Family Models from the Heterotic String". In PARTICLES, STRINGS, AND COSMOLOGY: 11th International Symposium on Particles, Strings, and Cosmology; PASCOS 2005. AIP, 2005. http://dx.doi.org/10.1063/1.2149703.

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Mirhaj, S. A., E. Kaarstad e B. S. Aadnoy. "Torque and Drag Modeling; Soft-string versus Stiff-string Models". In SPE/IADC Middle East Drilling Technology Conference and Exhibition. Society of Petroleum Engineers, 2016. http://dx.doi.org/10.2118/178197-ms.

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LEBEDEV, OLEG. "CP PHENOMENOLOGY IN HETEROTIC STRING MODELS". In Proceedings of the First International Conference. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812704917_0030.

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"Five Dimensional Mesonic String Cosmological Models". In 4th International Conference on Advances in Engineering Sciences and Applied Mathematics. International Institute of Engineers, 2015. http://dx.doi.org/10.15242/iie.e1215029.

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SAGNOTTI, AUGUSTO. "OPEN-STRING MODELS WITH BROKEN SUPERSYMMETRY". In Proceedings of the 25th Johns Hopkins Workshop on Current Problems in Particle Theory. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812791368_0024.

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Liao, Chien-Min, Balakumar Balachandran e Mansour Karkoub. "Drill-String Dynamics: Reduced-Order Models". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10339.

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Research efforts are underway to model and study the dynamics of a drill string, and preliminary results are presented in this work. The dynamics of a drill string system has non-smooth characteristics. Moreover, the drill string system dynamics exhibits qualitative changes with respect to the rotation speed of the drill string and friction coefficients associated with the contact between the drill string and the outer shell and the drill string and the well bottom. The coupling between torsion, lateral, and axial vibrations and the nonlinear interactions between them need to be investigated to better understand the dynamic behavior of the drill string system. As a preliminary step towards understanding the dynamics of the drill string, four-degree-of-freedom models are developed for the system by using two rotating sections: an inner stator that can undergo radial displacements and an outer rotor. Stickslip interactions between the drill string and the outer shell are also considered in the model development. Two sets of differential equations are obtained for the system by using displacements and momenta as system states in one model and displacements and velocities as system states in another model. For different values of friction coefficients, rotation speeds, and rotation torques, the results obtained by using the developed models are presented, discussed, and compared with experimental results.

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Rizos, John, Ioannis Florakis e Konstantinos Violaris-Gountonis. "On nonsupersymmetric Pati-Salam string models". In Corfu Summer Institute 2021 "School and Workshops on Elementary Particle Physics and Gravity". Trieste, Italy: Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.406.0061.

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Relatórios de organizações sobre o assunto "String models"

Bergman, O., e C. B. Thorn. String bit models for superstring. Office of Scientific and Technical Information (OSTI), dezembro de 1995. http://dx.doi.org/10.2172/179289.

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Gaver, Donald P., e Patricia A. Jacobs. In Search of Military Unit Formations: G-String Models. Fort Belvoir, VA: Defense Technical Information Center, janeiro de 1999. http://dx.doi.org/10.21236/ada360376.

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Ratigan. L52293 Brine String Integrity Survey and Model Evaluation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), janeiro de 2009. http://dx.doi.org/10.55274/r0010206.

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Brine strings are essential components of both natural gas and liquid hydrocarbon storage caverns. Both the natural gas and liquid hydrocarbon storage industries are well aware that a limit exists for the fluid velocity in the injection tubulars in their storage caverns. If the brine injection or brine withdrawal velocity is gradually increased, eventually, the hanging tubular will experience flow-induced vibration, resulting in the potential for the hanging tubulars to bend and/or break. Additionally, in both types of hydrocarbon storage, salt falls can impact the brine string integrity.Result: The magnitude of the velocity limit for flow-induced vibration of the hanging tubulars in salt caverns is not known. In the absence of a clearly defined method for determining the maximum allowable fluid velocities in the hanging tubulars, much of industry has attempted to adopt a conservative maximum flow velocity based on "industry experience". Sometimes this works and sometimes it does not. The objective of this project is to better define the causes of brine string failure and failure mitigation technologies. The project (1) compiled case histories of successful brine string installations as well as brine string failures in solution mining, liquid hydrocarbon storage, and gas cavern dewatering; (2) evaluated case histories with models (proposed in the literature) for brine strings that have not failed as well as brine strings that have experienced failure; and (3) developed recommendations for maximizing brine string integrity.

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Paidoussis, Michael. PR-593-18700-R01 Brine String Dynamics IV Deformation-Vibration in Solution Mined Caverns. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), maio de 2021. http://dx.doi.org/10.55274/r0012099.

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The research described in this report is focused on the dynamics of the brine strings utilized in solution-mined caverns. In Configuration 3, fluid enters the system from the top of the brine string and exits via the annulus between the brine string and the casing. In Configuration 4 the flows are inverted. An improved analytical model for stability of the brine string in Configuration 3 has been generated, and considerably better modelling for Configuration 4 achieved. Experiments in a bench-top sized system and CFD work were pursued partly to further improve the analytical models, and partly to explain some unexpected observations from a full-scale cavern, reported by Reitze in 2019. Note: Phase IV of this research was funded jointly by the Solution Mining Research Institute (SMRI) and Pipeline Research Council International (PRCI), and SMRI has published this same report with some formatting differences.

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Caballero, Juan, Stephen McCamant, Adam Barth e Dawn Song. Extracting Models of Security-Sensitive Operations using String-Enhanced White-Box Exploration on Binaries. Fort Belvoir, VA: Defense Technical Information Center, março de 2009. http://dx.doi.org/10.21236/ada538848.

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Faraggi, A. E., e J. C. Pati. A family-universal anomalous U(1) in string models as the origin of supersymmetry breaking and squark degeneracy. Office of Scientific and Technical Information (OSTI), dezembro de 1997. http://dx.doi.org/10.2172/604324.

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Kinikles, Dellena, e John McCartney. Hyperbolic Hydro-mechanical Model for Seismic Compression Prediction of Unsaturated Soils in the Funicular Regime. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, dezembro de 2022. http://dx.doi.org/10.55461/yunw7668.

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A semi-empirical elasto-plastic constitutive model with a hyperbolic stress-strain curve was developed with the goal of predicting the seismic compression of unsaturated sands in the funicular regime of the soil-water retention curve (SWRC) during undrained cyclic shearing. Using a flow rule derived from energy considerations, the evolution in plastic volumetric strain (seismic compression) was predicted from the plastic shear strains of the hysteretic hyperbolic stress-strain curve. The plastic volumetric strains are used to predict the changes in degree of saturation from phase relationships and changes in pore air pressure from Boyle’s and Henry’s laws. The degree of saturation was used to estimate changes in matric suction from the transient scanning paths of the SWRC. Changes in small-strain shear modulus estimated from changes in mean effective stress computed from the constant total stress and changes in pore air pressure, degree of saturation and matric suction, in turn affect the hyperbolic stress-strain curve’s shape and the evolution in plastic volumetric strain. The model was calibrated using experimental shear stress-strain backbone curves from drained cyclic simple shear tests and transient SWRC scanning path measurements from undrained cyclic simple shear tests. Then the model predictions were validated using experimental data from undrained cyclic simple shear tests on unsaturated sand specimens with different initial degrees of saturation in the funicular regime. While the model captured the coupled evolution in hydro-mechanical variables (pore air pressure, pore water pressure, matric suction, degree of saturation, volumetric strain, effective stress, shear modulus) well over the first 15 cycles of shearing, the predictions were less accurate after continued cyclic shearing up to 200 cycles. After large numbers of cycles of undrained shearing, a linear decreasing trend between seismic compression and initial degree of saturation was predicted from the model while a nonlinear increasing-decreasing trend was observed in the cyclic simple shear experiments. This discrepancy may be due to not considering post shearing reconsolidation in the model, calibration of model parameters, or experimental issues including a drift in the position of the hysteretic shear-stress strain curve. Nonetheless, the trend from the model is consistent with predictions from previously- developed empirical models in the funicular regime of the SWRC. The developments of the new mechanistic model developed in this study will play a key role in the future development of a holistic model for predicting the seismic compression across all regimes of the SWRC.

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Chong, Alberto E., e Mark Gradstein. Who Needs Strong Leaders? Inter-American Development Bank, janeiro de 2008. http://dx.doi.org/10.18235/0010883.

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This papers model suggests that a strong leader, sometimes with little legislative oversight, may nevertheless benefit from public support. The argument is that this support is induced as an attempt by the poor to counter the subversion of public protection of property rights by the rich, and to achieve this goal they are often willing to pay the price of the leaders diversion of tax revenues for private use. The paper then examines survey data on individual attitudes toward strong leadership and finds their pattern to be consistent with the models predictions; specifically, support for strong leadership is inversely related to individual income and to countrywide income inequality.

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Holman, R., S. Hsu, T. Vachaspati e R. Watkins. Metastable cosmic strings in realistic models. Office of Scientific and Technical Information (OSTI), novembro de 1992. http://dx.doi.org/10.2172/10188358.

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Kachru, Shamit. Linear Sigma Models for Open Strings. Office of Scientific and Technical Information (OSTI), setembro de 2001. http://dx.doi.org/10.2172/798874.

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