Bibliographies thématiques / Minimal curvature strings

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Littérature scientifique sur le sujet « Minimal curvature strings »

Auteur : Grafiati

Publié le 2 juin 2025

Mis à jour le 31 juillet 2025

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Articles de revues sur le sujet "Minimal curvature strings"

Sanchez, N. G. "Advances in String Theory in Curved Backgrounds: A Synthesis Report." International Journal of Modern Physics A 18, no. 12 (2003): 2011–22. http://dx.doi.org/10.1142/s0217751x0301543x.

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A synthetic report of the advances in the study of classical and quantum string dynamics in curved backgrounds is provided, namely : the new feature of Multistring solutions; the mass spectrum of Strings in Curved backgrounds; The effect of a Cosmological Constant and of Spacial Curvature on Classical and Quantum Strings; Classical splitting of Fundamental Strings; The General String Evolution in constant Curvature Spacetimes; The Conformal Invariance Effects; Strings on plane fronted and gravitational shock waves, string falling on spacetime singularities and its spectrum. New Developments in

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Kotb, Mahmoud. "Nambu-Goto Strings viaWeierstrass Representation." JOURNAL OF ADVANCES IN PHYSICS 13, no. 4 (2017): 4985–92. http://dx.doi.org/10.24297/jap.v13i6.6245.

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A description of string model of gauge theory are related to minimal surfaces. notations of minimal surface and related mean and Gauss curvature discussed. The Weierstrass representation for a surface conformally which immersed in R used to represent Nambu- Goto action, action of Nambu Goto is calculated usingWeierstrass representation which can be used to calculate the Partion Function and potential, then a non-perturbative solution for action is aimed and fulfilled and a consequences of that are investigated and its mathematical and physical properties are discussed.

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ALEXEYEV, S. O., M. V. SAZHIN, and M. V. POMAZANOV. "BLACK HOLES OF A MINIMAL SIZE IN STRING GRAVITY." International Journal of Modern Physics D 10, no. 02 (2001): 225–30. http://dx.doi.org/10.1142/s0218271801000780.

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A lower limit for a neutral black hole size is obtained in the frames of the string gravity model with the second order curvature correction. It is shown that this effect remains when the third order curvature correction is also taken into account and argued that such restriction does exist in all perturbative orders of curvature expansions.

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Conzinu, P., G. Fanizza, M. Gasperini, E. Pavone, L. Tedesco, and G. Veneziano. "Constraints on the Pre-Big Bang scenario from a cosmological interpretation of the NANOGrav data." Journal of Cosmology and Astroparticle Physics 2025, no. 02 (2025): 039. https://doi.org/10.1088/1475-7516/2025/02/039.

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Abstract We discuss a recently proposed fit of the 15-year data set obtained from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) in terms of a relic stochastic background of primordial gravitons, produced in the context of the string cosmology pre-big bang scenario. We show that such interpretation cannot be reconciled with a phenomenologically viable minimal version of such scenario, while it can be allowed if one considers an equally viable but generalised, non-minimal version of pre-big bang evolution. Maintaining the S-duality symmetry throughout the high-curva

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ABDALLA, E., та A. LIMA-SANTOS. "FACTORIZABLE S-MATRIX FOR $\frac{{\rm SO} (D)}{{\rm SO} (2) \otimes {\rm SO} (D -2)}$ NON-LINEAR σ MODELS WITH FERMIONS". Modern Physics Letters A 03, № 03 (1988): 311–17. http://dx.doi.org/10.1142/s0217732388000374.

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We compute the exact S matrix for the non-linear sigma model with symmetry SO(D)/SO(2)⊗SO(D−2) coupled to fermions in a minimal or supersymmetric way. The model has some relevance in string theory with non-zero external curvature.

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Zhang, Binqi, Jingen Deng, Hai Lin, et al. "Study on Erosion Model Optimization and Damage Law of Coiled Tubing." Energies 16, no. 6 (2023): 2775. http://dx.doi.org/10.3390/en16062775.

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Coiled tubing (CT) is used as a velocity string to transport high-velocity gas in drainage gas recovery technology. Sand particles flowing at high speed can cause serious erosion of the pipe wall. Long-term erosion wear leads to the degradation of the string strength and can even cause local perforation. In order to study the erosion wear problem of CT, a gas–solid erosion experimental device was established for a full-size pipe with different radii of curvature. A 3D laser confocal technique was used to examine and characterize the microscopic erosion morphology of the inner wall of the CT. T

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Ahmad, Daud, and Bilal Masud. "A Coons Patch Spanning a Finite Number of Curves Tested for Variationally Minimizing Its Area." Abstract and Applied Analysis 2013 (2013): 1–15. http://dx.doi.org/10.1155/2013/645368.

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In surface modeling a surface frequently encountered is a Coons patch that is defined only for a boundary composed offouranalytical curves. In this paper we extend the range of applicability of a Coons patch by telling how to write it for a boundary composed of an arbitrary number of boundary curves. We partition the curves in a clear and natural way into four groups and then join all the curves in each group intooneanalytic curve by using representations of the unit step function including one that isfully analytic. Having a well-parameterized surface, we do some calculations on it that are m

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Avis Akbar, Sari Wulandari Hafsari, and Lia Yunita. "Evaluasi Penyimpangan Lintasan Pengeboran Berarah Dan Pengaruhnya Terhadap Pembebanan Drill String pada Sumur “A-A” Lapangan "CPG." Jurnal Offshore: Oil, Production Facilities and Renewable Energy 8, no. 1 (2024): 24–36. https://doi.org/10.30588/jo.v8i1.2015.

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In drilling activities, wellbores inevitably experience deviation, commonly referred to as a crooked hole. If the deviation is significant, the loading on the drill string becomes one of the reasons why drilling does not go as planned and may even fail. The purpose of the research is to determine whether there is a deviation in the drilling path between the planned trajectory and the actual trajectory in well 'A-A' in the CPG field. By evaluating the drilling path deviation, it can be determined whether the load experienced by the drill string exceeds the predefined limits. The Minimum of Curv

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D’AURIA, RICCARDO, PIETRO FRE’, GUIDO DE MATTEIS, and IGOR PESANDO. "SUPERSPACE CONSTRAINTS AND CHERN-SIMONS COHOMOLOGY IN D=4 SUPERSTRING EFFECTIVE THEORIES." International Journal of Modern Physics A 04, no. 14 (1989): 3577–613. http://dx.doi.org/10.1142/s0217751x89001412.

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The linear multiplet, composed of the dilaton ϕ, of an antisymmetric gauge field Bμν and of a spinor χ is always present in any superstring induced N=1D=4 supergravity model. We consider its coupling to supergravity using only superspace Bianchi identities and the rheonomy approach. In this way, our results are fully general and independent from the choice of any Lagrangian, a concept which is never mentioned in this paper. We consider two situations corresponding to two different free differential algebras: (1) the case where there are no Chern-Simons terms in the Bμν field strength Hμνρ and

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Emmerson, Parker Yaohushuason. "Geometry of Phenomenological Velocity: Energy Numbers, Curvature and Fukaya-Type Categories." May 27, 2025. https://doi.org/10.5281/zenodo.15523017.

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Thank you, Yaohushua for letting me continue to distribute these mathematical gesturing forms so interesting. The paper constructs an algebraic–geometric framework around the “phenomenological ve-locity” expression v = pN/D that arose in previous informal work. We introduce (i) theenergy-number field E, (ii) a non-commutative velocity-string algebra V, (iii) a curvature scalarKPV defined from a “PV–Hessian”, and (iv) a curved A∞ category Fukv (M ) obtained from anordinary Fukaya category by multiplication with v. Basic structural results are proved; se

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Actes de conférences sur le sujet "Minimal curvature strings"

Samuel, Robello. "A Compelling Case: Time to Change Minimum Curvature Survey Method for Well Engineering Calculations." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21258-ms.

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Abstract Several calculation methods have been proposed by the researchers in the past with varying degree of precision. These result in different wellbore position estimation. The survey calculations and positions are used in engineering calculations such as torque and drag, drill ahead prediction, displacement of the string, SAG correction etc. Since the survey calculations are the underpinning starting point for the engineering formulations, considerable errors are introduced in the engineering calculations. Most widely used method in the industry is minimum curvature which assumes a circul

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Samuel, Robello. "Engineers’ Trilemma: Use and Limitation of Torque and Drag Models." In SPE/IADC International Drilling Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212552-ms.

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Abstract Different methods to calculate torque and drag have been used by the oil industry for years. Various assumptions are used in formulating these models. Opinions have often varied as to which model is better and whether the assumptions are valid. This paper discusses the trilemma considerations for an engineer 1. Soft string model vs stiff string model 2. Survey calculation method based on minimum curvature 3. Appearing and vanishing tortuosities after the casings have been run. Because of various underlying assumptions, the friction factor calibration is done often to match the calcula

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Clayton, Luke Michael, Ming Hwa Lee, and Alireza Salmachi. "Alleviating Directional Well Trajectory Problems via Data Analytics." In SPE Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/210766-ms.

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Abstract A consistent leading cause of drilling non-productive time (NPT) is the inability to steer the planned well trajectory trouble-free. Separate from downhole tool and drill bit failures, an unplanned trip to change the Bottom Hole Assembly (BHA) is required for up to one in every seven drilling runs. Root cause analyses indicate potentially a quarter of all drilling NPT has poor planning or field execution as the failure mechanism, signifying scope for improvement. This paper aims to help guide optimal selection of RSS/motor and bit, to ensure challenging wellpaths will be achieved with

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Schaefer, Frank R., Marc Ramsey, Imtiaz Haque, and Jürgen Schuller. "Development of Target Point Search Methods for Course Following Systems: Treating Vehicle Control." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1206.

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Abstract This paper addresses target point search methods for course following systems. A central concept in the development of the control algorithms for such systems is that of target point selection. For a given driving situation, target points constitute spatial objectives that the control algorithm strives to realize. The results presented in this paper are based on experiments made with a recently developed new driver model [Schaefer and Schuller, 1999]. The model establishes control in two steps: geometric dynamic planning and plan-to-action mapping. The separation into these two units

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Samuel, Robello, Jonathan Dale Lightfoot, and William Turner. "Mechanical and Geometrical Tortuosities: Vanishing and Appearing Tortuosities." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206188-ms.

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ABSTRACT Tortuosity is one of the critical factors to be considered for complex directional well trajectories, complicated build rates, precise steering in thin reservoirs, and extended reach wells. This paper discusses the pitfalls of estimating tortuosity to quantify borehole quality and answers questions, such as whether the claimed benefits (i.e., enhanced drilling performance, improved hole cleaning, ease of running casing, and superior cement operations) can be fully attributed to reduced borehole tortuosity. Running casing may mask the tortuosity present in the as drilled open hole well

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Gutierrez, David, Nate Anderson, Chad Hanak, Tim Paton, Julia Vallejos, and Nick Brown. "Real-Time Wellbore Placement Improvement with High-Fidelity Trajectory Estimation and Dual-Sensor MWD Packages." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206253-ms.

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Abstract High-fidelity trajectory estimation combined with dual-probe Measurement-While-Drilling (MWD) directional instrumentation provides a solution to minimum curvature’s known inefficiencies in modeling the true wellbore position and definition (Stockhausen & Lesso, 2003). While it may not be cost efficient to increase survey frequency from the industry standard of 30ft-200ft, it is possible using the techniques defined in this research to maintain current survey intervals and increase wellbore placement accuracy while reducing positional uncertainty by up to 45% over the most advanced

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