Relevant bibliographies by topics / Black hole structure

Academic literature on the topic 'Black hole structure'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Black hole structure"

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Kumar, Jitendra, Shafqat Ul Islam, and Sushant G. Ghosh. "Loop Quantum Gravity motivated multihorizon rotating black holes." Journal of Cosmology and Astroparticle Physics 2022, no. 11 (November 1, 2022): 032. http://dx.doi.org/10.1088/1475-7516/2022/11/032.

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Abstract With a semiclassical polymerization in the loop quantum gravity (LQG), the interior of the Schwarzschild black holes provides a captivating single-horizon regular black hole spacetime. The shortage of rotating black hole models in loop quantum gravity (LQG) substantially restrains the progress of testing LQG from observations. Motivated by this, starting with a spherical LQG black hole as a seed metric, we construct a rotating spacetime using the revised Newman-Janis algorithm, namely, the LQG-motivated rotating black holes (LMRBH), which encompasses Kerr (l = 0) black holes as an exceptional case. We discover that for any random l > 0, unlike Kerr black hole, an extremal LMRBH refers to a black hole with angular momentum a > M. The rotating metric, in parameter space, describes (1) black holes with an event and Cauchy horizon, (2) black holes with three horizons, (3) black holes with only one horizon or (4) no horizon spacetime. We also discuss the horizon and global structure of the LMRBH spacetimes and its dependence on l/M that exhibits rich spacetime structures in the (M, a, l) parameter space.
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Ghosh, P. "The structure of black hole magnetospheres -- I. Schwarzschild black holes." Monthly Notices of the Royal Astronomical Society 315, no. 1 (June 11, 2000): 89–97. http://dx.doi.org/10.1046/j.1365-8711.2000.03410.x.

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Mahulikar, Shripad P., and Pallavi Rastogi. "Study of black hole as dissipative structure using negentropy." Canadian Journal of Physics 94, no. 10 (October 2016): 960–66. http://dx.doi.org/10.1139/cjp-2016-0388.

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The area of the event horizon of a black hole (Aeh) is so far linked only with its entropy (SBH). In this theoretical investigation, it is shown that relating Aeh only to SBH is inadequate, because Aeh is linked to the black hole’s negentropy, which encompasses its entropy. Increasing Aeh of black holes that grow now follows from the negentropy theorem (NET) and also from the well-known area theorem. The decreasing Aeh of black holes that decay follows from the converse to NET and is not a violation of the area theorem. The corollary to NET is proved for the case when two dissipative structures merge, which is the basis for the coalescence of black holes. The converse of corollary to NET explains negentropy loss due to splitting of a dissipative structure. When applied to black hole explosion (i.e., splitting into an infinite number of parts), converse of corollary to NET reduces to converse of NET. The entropy/energy ratio of the exported Hawking radiance from black holes contributes to the entropy increase of the universe. These aspects justify the consideration of black holes as thermodynamic dissipative structures.
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CHAKRABARTI, SAYAN K., KUMAR S. GUPTA, and SIDDHARTHA SEN. "UNIVERSAL NEAR-HORIZON CONFORMAL STRUCTURE AND BLACK HOLE ENTROPY." International Journal of Modern Physics A 23, no. 16n17 (July 10, 2008): 2547–61. http://dx.doi.org/10.1142/s0217751x08040482.

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It is shown that a massless scalar probe reveals a universal near-horizon conformal structure for a wide class of black holes, including the BTZ. The central charge of the corresponding Virasoro algebra contains information about the black hole. With a suitable quantization condition on the central charge, the CFT associated with the black hole in our approach is consistent with the recent observation of Witten, where the dual theory for the BTZ in the AdS/CFT framework has been identified with the construction of Frenkel, Lepowsky and Meurman. This CFT admits the Fischer–Griess monster group as its symmetry. The logarithm of the dimension of a specific representation of the monster group has been identified by Witten as the entropy of the BTZ black hole. Our algebraic approach shows that a wide class of black holes share the same near-horizon conformal structure as that for the BTZ. With a suitable quantization condition, the CFT's for all these black holes in our formalism can be identified with the FLM model, although not through the AdS/CFT correspondence. The corresponding entropy for the BTZ provides a lower bound for the entropy of this entire class of black holes.
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Nagatani, Yukinori. "Atomic Structure in Black Hole." Progress of Theoretical Physics Supplement 164 (2006): 54–67. http://dx.doi.org/10.1143/ptps.164.54.

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Deng, Gao-Ming, and Yong-Chang Huang. "Q − Φ criticality and microstructure of charged AdS black holes in f(R) gravity." International Journal of Modern Physics A 32, no. 35 (December 20, 2017): 1750204. http://dx.doi.org/10.1142/s0217751x17502049.

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The phase transition and critical behaviors of charged AdS black holes in [Formula: see text] gravity with a conformally invariant Maxwell (CIM) source and constant curvature are further investigated. As a highlight, this research is carried out by employing new state parameters [Formula: see text] and contributes to deeper understanding of the thermodynamics and phase structure of black holes. Our analyses manifest that the charged [Formula: see text]-CIM AdS black hole undergoes a first-order small–large black hole phase transition, and the critical behaviors qualitatively behave like a Van der Waals liquid–vapor system. However, differing from the case in Einstein’s gravity, phase structures of the black holes in [Formula: see text] theory exhibit an interesting dependence on gravity modification parameters. Moreover, we adopt the thermodynamic geometry to probe the black hole microscopic properties. The results show that, on the one hand, both the Ruppeiner curvature and heat capacity diverge exactly at the critical point, on the other hand, the [Formula: see text]-CIM AdS black hole possesses the property as ideal Fermi gases. Of special interest, we discover a microscopic similarity between the black holes and a Van der Waals liquid–vapor system.
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Gao, Shengyao, Zhou Tao, Yuhui Li, and Fuzhen Pang. "Application research of acoustic black hole in floating raft vibration isolation system." REVIEWS ON ADVANCED MATERIALS SCIENCE 61, no. 1 (January 1, 2022): 888–900. http://dx.doi.org/10.1515/rams-2022-0235.

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Abstract Acoustic black holes have good application prospects in the field of vibration and noise reduction. Based on engineering practice, this study proposes a systematic process method for the application of acoustic black hole structure in raft structure, which provides new ideas and references for improving the vibration isolation performance of floating raft system and reducing the level of ship vibration and noise. The influence law of each parameter on structural vibration and the recommended value range of each parameter are given, which provides support for the systematic method and process of the application of acoustic black holes in the raft structure. Then, the acoustic black hole process is applied to a floating raft system. According to the characteristics of the raft structure, an application scheme of the acoustic black hole in the raft structure is formed, and the vibration level drop of the floating raft vibration isolation system before and after the acoustic black hole is embedded, calculated, and analyzed. The changes further improve the vibration reduction and isolation performance of the raft system and effectively reduced the mechanical noise level of the ship’s cabin.
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Tang, Yang, Jiangtao Liu, Ning Liu, Fuzhen Pang, and Yu Wang. "Dynamic characteristic analysis of acoustic black hole in typical raft structure." REVIEWS ON ADVANCED MATERIALS SCIENCE 61, no. 1 (January 1, 2022): 458–76. http://dx.doi.org/10.1515/rams-2022-0038.

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Abstract As a hot content of research in recent years, acoustic black holes have bright application prospects in the field of vibration and noise reduction. In this article, based on the acoustic black hole theory, we carry out a study on the dynamic characteristics of a typical raft structure. The manuscript gives the simplified method of the acoustic black hole model, verifies the validity of the method by the structure natural frequency and vibration response, and discusses the influence of the main parameters such as acoustic black hole tip cutoff ratio and damping thickness ratio on the vibration characteristics of the raft frame structure. The better values of the parameters were applied to the raft structure on this basis, and the results showed that the peak value of some frequency points decreased by about 10 dB after the acoustic black hole was laid in the raft structure, which improved the vibration isolation performance of the raft.
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Shibata, K., S. Koide, T. Kudoh, and S. Aoki. "Jets from Black Hole Magnetospheres." Symposium - International Astronomical Union 195 (2000): 265–72. http://dx.doi.org/10.1017/s0074180900163028.

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Recent general-relativistic MHD simulations of jets ejected from black-hole magnetospheres (for both Schwarzschild and Kerr holes) have revealed that (1) strong shock waves are formed in the accretion flow inside 3rs, (2) jets show two-layered shell structure consisting of a gas-pressure driven jet and a magnetically driven jet, the former being accelerated from a high-pressure region heated by strong shocks, and (3) in the case of a Kerr hole, magnetically driven jets are produced from the ergosphere by the effect of frame dragging.
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HONG, SUNGWOOK E., DONG-HAN YEOM, and HEESEUNG ZOE. "CRITICAL REVIEWS ON HOLOGRAPHIC MEASURE OVER THE MULTIVERSE." International Journal of Modern Physics: Conference Series 01 (January 2011): 317–22. http://dx.doi.org/10.1142/s2010194511000468.

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In this talk, the holographic measure based on black hole complementarity is critically reviewed. By noticing the similarities between the causal structure of an inflationary dS space and that of a black hole, we have considered the complementarity principle between the inside and the outside of the causal horizon as an attractive way to count the inflationary multiverse. Even though the holographic measure relieves the Boltzmann brain problem and stresses the physical reality based on observations, it could be challenged by the construction of counterexamples, both on regular black holes and charged black holes, to black hole complementarity.
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Dissertations / Theses on the topic "Black hole structure"

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Riedel, Gårding Elias. "Quantum structure of holographic black holes." Thesis, KTH, Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284694.

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We study a free quantum scalar field in the BTZ spacetime as a model of the AdS/CFT correspondence for black holes, and show the essential steps in computing Bogolyubov coefficients between modes on either side of the wormhole. As background, we review the BTZ geometry in standard, Kruskal and Poincaré coordinates, holographic renormalisation of the dual field theory and canonical quantisation in curved spacetime.
Vi studerar ett fritt skalärt kvantfält i BTZ-rumtiden som en modell av AdS/CFT-dualiteten för svarta hål och visar huvudstegen i beräkningen av Bogolyubov-koefficienter mellan moder på olika sidor av maskhålet. Som bakgrund redogör vi för BTZ-geometrin i standard-, Kruskal- och Poincarékoordinater, holografisk renormering av den duala fältteorin och kanonisk kvantisering i krökt rumtid.
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Ryle, Wesley Thomas. "Investigation of Fundamental Black Hole Properties of AGN through Optical Variability." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/phy_astr_diss/25.

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Active galactic nuclei (AGN) are known to vary in brightness in all regions of the electromagnetic spectrum and over a wide range of timescales. Many methods have been utilized to transform this observed variability into meaningful information about the central engines of AGN. One such technique, adapted from time series analysis of galactic x-ray binary systems, has been used to detect a characteristic break timescale in the power density spectra of x-ray variability in Seyfert galaxies. This timescale, thought to be related to instabilities in the accretion disk, appears to scale with black hole mass over many orders of magnitude. This dissertation performs similar time series analyses with the optical data of eight blazars. The majority of these objects also display a characteristic break timescale. In cases where a black hole estimate is known, the timescales are in good agreement with the relationship observed for galactic x-ray binary systems and Seyfert galaxies. For objects of unknown mass, this relationship can be used to provide a mass estimate of the supermassive black hole. Comparisons are made between the structure function and power density spectrum for each object, and the implications for the connection between the accretion disk and the relativistic jet in AGN are discussed.
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Bellisardi, Federico. "Study of gaseous structures in axisymmetric rotation in presence of a black hole." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18422/.

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L’oggetto di tale tesi é lo studio di sistemi gassosi in rotazione assisimmetrica con distribuzioni barocline. Nella prima parte dell’elaborato, vengono discussi i concetti fondamentali della dinamica dei fluidi; le equazioni del moto di fluidi in rotazione soggetti ad un potenziale gravitazionale vengono derivate e studiate. Successivamente viene introdotta l’analisi sulla stabilità lineare e vengono derivati i criteri di Schwarzschild e di Rayleigh. Tali criteri vengono poi generalizzati introducendo il criterio di Solberg-Hoiland. Soluzioni stazionarie per fluidi in rotazione assisimmetrica vengono introdotte e vengono discusse le differenze nei casi barotropico e baroclino. Viene poi presentata una famiglia di sistemi baroclini in equilibrio in un potenziale gravitazionale assisimmetrico. Successivamente ho considerato una famiglia di tori gassosi con una distribuzione di densità a legge di potenza. Sono stati studiati due casi: tori auto-gravitanti e tori in equilibrio in presenza della loro auto-gravità e di un buco nero centrale. Infine, il criterio di Solberg-Hoiland é stato utilizzato per determinare in quali condizioni i sistemi toroidali auto-gravitanti sono linearmente stabili e per ottenere una formulazione analitica della condizione di stabilità per tori in equilibrio in presenza della loro auto-gravità e di un buco nero centrale.
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Lee, Chih Yun. "Funding the Black Hole: The Ineffectiveness of the Current Retirement Plan Structure and Future Solutions." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/cmc_theses/629.

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This paper seeks to examine the failures of the current retirement plan structure, focusing on the structure’s reliance on unpredictable future market returns and the unwillingness of the parties involved to negotiate in order to further enhance their own self-centered interests. Currently, both defined contribution and defined benefit plans encounter a funding crisis in both the public and the private sectors. This paper will discuss how retirement plans, by nature, rely on assumptions of market returns, which naturally depend on the volatility of the market and increase the risk and uncertainty in retirement plans. In addition, since defined benefit plans mostly exist in the public sector today, this paper will examine defined benefit plans in relation to the public sector’s funding crisis and hope to shed light on the politics and tensions between the parties involved in public retirement plans that are preventing effectiveness and efficiency. Finally, this paper will also present alternative retirement plan strategies for which academics and scholars have advocated. However, at the end of the day, as opposed to relying on others to dictate one’s future benefits, which are based on the goodwill of others and uncertainty in the market, Americans should recognize their lack of savings and improve their personal financial literacy and develop individualized savings plans.
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Leng, Julien. "Controlling flexural waves using subwavelength perfect absorbers : application to Acoustic Black Holes." Thesis, Le Mans, 2019. http://www.theses.fr/2019LEMA1027/document.

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Le contrôle des vibrations à basse fréquence adapté aux structures légères est un défi scientifique ettechnologique en raison de contraintes économiques et écologiques de plus en plus strictes. De récentes études enacoustique ont portées sur l’absorption totale d’ondes basses fréquences à l’aide d’absorbeurs parfaits sublongueursd’onde. Ces métamatériaux sont obtenus en exploitant la condition de couplage critique. Unegénéralisation de cette méthode pour le domaine élastodynamique serait d’un grand intérêt pour répondre auxexigences du contrôle des vibrations de structures légères à basse fréquence.Cette thèse vise à adapter le problème d’absorption parfaite des ondes de flexion dans des systèmes 1D et 2D avecdes résonateurs locaux en utilisant la condition de couplage critique. Une étude préliminaire sur des systèmes 1D àgéométries simples sont d’abord proposée. Celle-ci propose une méthode de conception de résonateurs simplespour une absorption efficace des ondes de flexion. Une complexification du système 1D est ensuite considérée avecl’étude du couplage critique de Trou Noir Acoustique (TNA) 1D. Ceci a motivé l’interprétation de l’effet TNA à l’aidedu concept de couplage critique afin de présenter des outils clés à de futures procédures d’optimisation pour ce typede terminaisons. La condition de couplage critique est ensuite étendue aux systèmes 2D. L’absorption parfaite parle premier mode axisymétrique d’un résonateur circulaire inséré dans une plaque mince infinie est analysée. Ladiffusion multiple par une ligne de résonateurs circulaires insérés dans une plaque mince 2D infinie ou semi-infinie,appelée métaplaque, est aussi considérée dans l’optique de se rapprocher d’une application industrielle. A traverscette thèse, des modèles analytiques, des simulations numériques et des expériences sont présentés pour valider lecomportement physique des systèmes présentés
The vibration control adapted to light structures is a scientific and technological challenge due toincreasingly stringent economic and ecological standards. Meanwhile, recent studies in audible acoustics havefocused on broadband wave absorption at low frequencies by means of subwavelength perfect absorbers. Suchmetamaterials can totally absorb the energy of an incident wave. The generalisation of this method for applicationsin elastodynamics could be of great interest for the vibration control of light structures.This thesis aims at adapting the perfect absorption problem for flexural waves in 1D and 2D systems with localresonators using the critical coupling condition. A study of 1D systems with simple geometries is first proposed. Thisprovides methods to design simple resonators for an effective absorption of flexural waves. The 1D systems thenbecome more complex by studying the critical coupling of 1D Acoustic Black Holes (ABH). The ABH effect is theninterpreted using the concept of critical coupling, and key features for future optimisation procedures of ABHs arepresented. The critical coupling condition is then extended to 2D systems. The perfect absorption by the firstaxisymmetric mode of a circular resonator inserted in a thin plate is analysed. Multiple scattering by an array ofcircular resonators inserted in an infinite or semi-infinite 2D thin plate, called metaplate, is also considered to getclose to practical applications. Through this thesis, analytical models, numerical simulations and experiments areshown to validate the physical behaviour of the systems presented
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Cochet, Some Claire. "Numerical characterization of boson stars and Kerr Black holes." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC094.

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Le Centre de notre Galaxie est l'endroit idéal pour observer les effets de fort champ gravitationnel. Bien que l'on suppose généralement que la source radio compacte située en son centre et appelée Sgr A* soit un trou noir en rotation, des modèles alternatifs permettent d'expliquer les observations actuelles. Ce travail considère un de ces autres objects possibles : l'étoile bosonique. Les étoiles bosoniques en rotation sont des solutions numériques du système déquations couplées Einstein-Klein-Gordon, donc ces équations sont ici écrites sous forme 3+1 et un code numérique capable de les résoudre est présenté grâce à la bibliothèque Kadath. Plusieurs types d'étoiles bosoniques sont présentées avec différents potentiels tels que les champs libres, les champs auto-interagissants, des potentiels quartiques et sextiques, et différentes valeurs du nombre rotationnel quantique. Ensuite deux méthodes différentes de comparaison de ces espace-temps à celui de Kerr sont présentés. Le premier consiste à tracer les géodésiques de genre temps dans cette géométrie et à les étudier. Le code de ray-tracing appelé Gyoto a été utilisé pour intérger numériquement les équations géodésiques pour différents types d'étoiles bosoniques. Un type d'orbites particulier a été identifié : celles dont le moment angulaire est nul, elles ont été appelées orbites en "pétales pointus" à cause de leur forme. Ces orbites passent très près du centr et sont qualitativement différentes des orbites autour d'un trou noir de Kerr. Un autre moyen de comparer Kerr à un espace-temps stationnaire, asymptotiquement plat donné sous forme 3+1 est d'utiliser une caractérisation de l'espace-temps de Kerr donnée par le tenseur de Simon-Mars. Ce tenseur a la propriété d'être identiquement nul pour un espace-temps vide et asymptotiquement plat si et seulement si cet espace-temps est localement isométrique à celui de Kerr. L'idée est donc de construire une quantité scalaire, qui est un facteur de qualité invariant, de l'écrire sous forme 3+1 pour pouvoir le calculer grâce à des codes numériques. Calculer cette quantité permet d'obtenir une manière simple de comparer localement n'importe quel espace-temps stationnaire (même non vide et non analytique) à l'espace-temps de Kerr, cela donnant une mesure de sa déviation à Kerr. Comme illustration, ce facteur de qualité invariant est évalué pour des solutions numériques des équations d'Einstein générées par des étoiles bosoniques et des étoiles à neutrons, et pour des solutions analytiques de ces équations telles que l'espace-temps de Curzon-Chazy
The Galactic Center is an interesting place to test possible effects of strong gravity regime. Whereas it is generally believed that the compact object located at the Galactic Center, named Sgr A*, is a rotating black hole, some alternative models can also explain the current observations. This work is centered on one of these other objects, which is the Boson Star. Rotating boson stars are numerical solutions of the coupled Einstein-Klein-Gordon system, so these equations are written within the 3+1 formalism and then a numerical code capable of solving them with the Kadath library has been developed. Several kinds of boson stars with different potentials are presented : free fields an self-interacting fields, with quartic and sextic potentials, and different values of the rotational quantum number. Then two different ways of comparing this spacetime to Kerr's are presented. One way was to compute timelike geodesics in this geometry and study them. For that the ray-tracing code Gyoto is used to integrate numerically the geodesic equations for several types of boson stars. A peculiar type of orbits has been identifyed: the zero-angular-momentum ones which is called pointy-petal orbits thanks to their shape. These orbits pass very close to the center and are qualitatively different from orbits around a Kerr black hole. Another way to compare Kerr to any stationary and asymptotically flat metric given in its 3+1 form was to us a the characterization of the Kerr spacetime given by the Simon-Mars tensor. This tensor has the property of being identically zero for a vacuum and asymptotically flat spacetime if and only if the latter is locally isometric to the Kerr spacetime. The idea was to build a scalar with this tensor, and a scalar which is an invariant quality factor. Then, write it in 3+1 form to be able to compute it with numerical codes such as Kadath. Computing this scalar provides a simple way of comparing locally a generic (even non vacuum and non analytic) stationary spacetime to Kerr, therefore measure its 'non-Kerness". As an illustration, this invariant quality factor is evaluated for numerical solutions of the Einstein equations generated by boson stars and neutron stars, and for analytic solutions of the Einstein equations such as Curzon Chazy spacetime
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Bowyer, E. P. "Experimental investigation of damping structural vibrations using the acoustic black hole effect." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10983.

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This thesis describes the results of the experimental investigations into some new geometrical configurations in plate-like structures materialising one-dimensional (1D) acoustic black holes for flexural waves (wedges of power-law profile) and two-dimensional (2D) acoustic black holes for flexural waves (circular indentations of power-law profile). Such acoustic black holes allow the user to reduce the amplitudes of the vibration responses of plate-like structures to a maximum effect, while not increasing the mass of the structures. This thesis also suggests some new real world practical applications for this damping technique. Initially, the effects of geometrical and material imperfections on damping flexural vibrations in plates with attached wedges of power-law profile (1D black holes) were investigated, demonstrating that this method of damping is robust enough for practical applications. Then, damping of flexural vibrations in turbofan blades with trailing edges tapered according to a power-law profile has been investigated. In addition, experimental investigations into power-law profiled slots within plates have been also conducted. Another important configuration under investigation was that of circular indentations (pits) of power-law profile within the plate. In the case of quadratic or higher-order profiles, such indentations materialise 2D acoustic black holes for flexural waves. To increase the damping efficiency of power-law profiled indentations, the absorption area has been enlarged by increasing the size of the central hole in the pit, while keeping the edges sharp. The next step of investigation in this thesis was using multiple indentations of power-law profile (arrays of 2D black holes). It was shown that not only do multiple indentations of power-law profile provide substantial reduction in the damping of flexural vibrations, but also a substantial reduction in radiated sound power. The experimental results have been obtained also for a cylindrical plate incorporating a central hole of quadratic profile. They are compared to the results of numerical predictions, thus validating the results and the experimental technique. Investigations into the effects of indentations of power-law profile made in composite plates and panels and their subsequent inclusion into composite honeycomb sandwich panels are also reported. These indentations again act as 2D acoustic black holes for flexural waves and they effectively damp flexural vibrations within the panels. It was also demonstrated that these indentations can be enclosed in smooth surfaced panels and that no additional damping layer is required to induce the acoustic black hole effect in composite structures. In conclusion, it has been confirmed in this thesis that one and two-dimensional acoustic black holes represent an effective method of damping flexural vibrations and reducing the associated structure-borne sound. Furthermore, this thesis has shown that acoustic black holes can be efficiently employed in practical applications, such as trailing edges of jet engine fan blades, composite panels, and composite honeycomb sandwich structures.
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Bergstedt, Viktor. "Spacetime as a Hamiltonian Orbit and Geroch's Theorem on the Existence of Fermions." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-432488.

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Over a century since its inception, general relativity continues to lie at the heart of some of the most researched topics in theoretical physics. It seems likely that the coveted solutions to problems like quantum gravity are to be found in an extension of general relativity, one which may only be visible in an alternate formulation of the theory.  In this thesis we consider the possibility of casting general relativity in the form of an initial value problem where spacetime is seen as the evolution of space. This evolution is shown to be constrained and of Hamiltonian type.  Not all spacetimes are physically acceptable. To be compatible with particle physics, one would like spacetime to accommodate fermions. Here we can take comfort in Geroch’s theorem, which implies that any spacetime that admits a Hamiltonian formulation automatically supports the existence of fermions. We review the elements that go into the proof of this theorem.
Allmän relativitetsteori har i över hundra år legat i teoretiska fysikens framkant. Det är möjligt att lösningarna på öppna problem som kvantiseringen av gravitation går att finna i en utvidgning av allmän relativitetsteori – och kanske uppenbarar sig denna utvidgning bara ur en alternativ formulering av teorin. I den här uppsatsen formuleras allmän relativitetsteori och dess Einsteinekvationer som ett begynnelsevärdesproblem, genom vilket rumtiden kan betraktas som rummets historia. Vi visar att rummets rörelseekvationer är Hamiltons ekvationer med tvångsvillkor.  Enligt partikelfysiken bör fermioner kunna finnas till i rumtiden. Härom kan vi åberopa Gerochs sats, enligt vilken rumtider som har en Hamiltonsk formulering också medger fermioner. Vi redogör för huvuddragen i beviset av Gerochs sats.
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Kawamuro, Taiki. "X-ray Studies on Nucleus Structures of Mass Accreting Supermassive Black Holes and Luminosity Function of Tidal Disruption Events." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225404.

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Deng, Jie. "Vibroacoustic modeling of acoustic blackhole applications in flat, curved andcomplex mechanical structures." Doctoral thesis, Universitat Ramon Llull, 2020. http://hdl.handle.net/10803/670666.

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Els forats negres acústics en mecànica (coneguts per les sigles ABHs, de l’anglès Acoustic Black Holes) solen estar formats per osques en bigues i plaques, el gruix de les quals decau segons una llei potencial. L’efecte de l’ABH és el d’alentir les velocitats de fase i de grup de les ones de flexió incidents de tal manera que, en teoria, faria falta un temps infinit perquè les ones arribessin al centre de l’ABH, si el gruix d’aquest últim fos exactament zero. Tanmateix, a la pràctica això no és possible tot i que es pot aconseguir una forta dissipació col·locant una capa de material esmorteïdor al centre de l’ABH, on es concentra la major part de l’energia de les ones. En els darrers anys, els ABHs no només s’han explotat com a mètode passiu per reduir vibracions estructurals i l’emissió corresponent de soroll, sinó que també s’ha explorat el seu potencial per altres aplicacions com la manipulació d’ones o la captació d’energia. Aquesta tesi té tres objectius principals. Així, doncs, després d'una introducció general als ABHs, el treball s’ha dividit en tres grans seccions. La primera aborda aplicacions dels ABHs en bigues rectes i plaques planes. Per començar, es proposa i s’analitza un voladís piezoelèctric amb un acabament d’ABH per capturar energia. A continuació es presenten ABHs en forma d’anell per tal d’aïllar punts d’excitació externs en plaques planes i així evitar la transmissió de vibracions. Finalment, es contemplen configuracions periòdiques de matrius d’ABHs per tal de col·limar feixos d'ones de flexió i concentrar la seva energia en zones predeterminades d’una placa. La segona part de la tesi proposa nous dissenys d’ABHs per a estructures amb curvatura. Aquestes són molt habituals en els sectors naval, aeronàutic i industrial, de manera que val la pena investigar si els ABH poden resultar alguns casos. La secció comença analitzant la inclusió d’ABHs en bigues circulars i es veu com això dona peu a l’aparició de fenòmens típics en sistemes periòdics. Acte seguit es proposa un ABH anular per reduir les vibracions en conductes cilíndrics. En concret, es tracten els casos d’un conducte simplement suportat amb un ABH anular, i el d’un conducte amb ABH, suports periòdics i rigidificadors. Per finalitzar la secció, s’investiguen els efectes dels ABH anulars en la radiació acústica del conducte tenint en compte el nivell de potència acústica, l’eficiència de radiació i la intensitat supersònica. La tercera part de la tesi és més curta que les anteriors i simula l’aïllament d'una placa amb múltiples ABHs, en el rang de mitja i alta freqüència. A tal efecte s’empra el mètode de l’anàlisi estadística de distribució modal d'energia (SmEdA: statistical modal energy distribution analysis). En aquesta secció, l’estructura amb ABHs ja no s’analitza com un element individual sinó que s’acobla a dues cavitats d’aire, formant part d’un sistema mecànic més complex. Al llarg de la tesi s’utilitza repetidament el mètode d’expansió gaussiana (GEM: Gaussian expansion method). Pel GEM entenem prendre funcions gaussianes com a base per resoldre equacions diferencials en derivades parcials en el marc del mètode de Rayleigh-Ritz. El GEM s’assembla molt als enfocaments d’ondetes, però ofereix alguns avantatges en el cas de condicions de contorn periòdiques. Al principi de la tesi s’exposa un breu repàs del GEM i, quan és necessari, s’aborda la seva reformulació per a un problema particular en el capítol corresponent.
Los agujeros negros acústicos en mecánica (conocidos por las siglas ABHs, del inglés Acoustic Black Holes) suelen estar formados por muescas en vigas y placas, el grueso de las cuales decae según una ley potencial. El efecto del ABH es el de ralentizar las velocidades de fase y de grupo de las ondas de flexión incidentes de tal modo que, en teoría, haría falta un tiempo infinito para que las ondas alcanzaran el centro del ABH, si el grueso de este último fuera exactamente cero. Sin embargo, en la práctica esto no es posible, aunque se puede conseguir una fuerte disipación colocando una capa de material amortiguador en el centro del ABH, donde se concentra la mayor parte de la energía de las ondas. En los últimos años, los ABHs no sólo se han explotado como método pasivo para reducir vibraciones estructurales y la consecuente emisión de ruido, sino que también se ha explorado su potencial para otras aplicaciones como la manipulación de ondas o la captación de energía. Esta tesis tiene tres objetivos principales. Así pues, tras una introducción general a los ABHs, el trabajo se ha dividido en tres grandes secciones. La primera aborda aplicaciones de los ABHs en vigas rectas y placas planas. Para empezar, se propone y analiza un voladizo piezoeléctrico con un acabado de ABH para capturar energía. A continuación, se presentan ABHs en forma de anillo para aislar puntos de excitación externos en placas planas y así evitar la transmisión de vibraciones. Finalmente, se contemplan configuraciones periódicas de matrices de ABHs para colimar haces de ondas de flexión y concentrar su energía en zonas predeterminadas de una placa. La segunda parte de la tesis propone nuevos diseños de ABHs para estructuras con curvatura. Estas son muy habituales en los sectores naval, aeronáutico e industrial, por lo que merece la pena investigar si los ABH pueden dar buenos resultados en algunos casos. La sección comienza analizando la inclusión de ABHs en vigas circulares y se ve como estos dan pie a la aparición de fenómenos típicos de sistemas periódicos. Seguidamente se propone un ABH anular para reducir las vibraciones en conductos cilíndricos. En concreto, se tratan los casos de un conducto simplemente soportado con un ABH anular, y el de un conducto con ABH, soportes periódicos y rigidificadores. Para finalizar la sección, se investigan los efectos de los ABH anulares en la radiación acústica del conducto teniendo en cuenta el nivel de potencia acústica, la eficiencia de radiación y la intensidad supersónica. La tercera parte de la tesis es más corta que las anteriores y simula el aislamiento de una placa con múltiples ABHs, en el rango de media y alta frecuencia. A tal efecto se emplea el método del análisis estadístico de distribución modal de energía (SmEdA: statistical modal energy distribution analysis). En esta sección, la estructura con ABHs ya no se analiza como un elemento individual, sino que se acopla a dos cavidades de aire formando parte de un sistema mecánico más complejo. A lo largo de la tesis se utiliza repetidamente el método de expansión gaussiana (GEM: Gaussian expansión method). Por GEM entendemos tomar funciones gaussianas como base para resolver ecuaciones diferenciales en derivadas parciales en el marco del método de Rayleigh-Ritz. El GEM se parece mucho a los enfoques de ondículas, pero ofrece algunas ventajas en el caso de condiciones de contorno periódicas. Al principio de la tesis se expone un breve repaso del GEM y, cuando es necesario, se aborda su reformulación para un problema particular en el capítulo correspondiente.
Acoustic black holes (ABHs) in mechanics usually consist of geometrical indentations on beams and plates having a power-law decreasing thickness profile. An ABH slows down the phase and group velocity of incident flexural waves in such a way that, ideally, it would take an infinite amount of time for them to reach the ABH center, if the latter had an exact zero thickness. Though this is not possible in practice, strong wave dissipation can be achieved by placing a damping layer at the central region of the ABH, where most vibration energy concentrates. In recent years, ABHs have been not only exploited as a passive means for structural vibration and noise reduction, but its potential for other applications like wave manipulation or energy harvesting have been also explored. The objective of this thesis is threefold. Therefore, after an initial overview the work is divided into three main parts. The first one deals with ABH applications on straight beams and flat plates. To start with, an ABH piezoelectric bimorph cantilever for energy harvesting is proposed and analyzed. Then, ring-shaped ABH indentations are suggested as a means of isolating external excitation points in flat plates and prevent vibration transmission. Finally, periodic ABH array configurations are contemplated to collimate flexural wave beams and focus energy at desired plate locations. The second part of the thesis proposes new ABH designs for curved structures. The latter are very common in the naval, aeronautical and industrial sectors so it is worth investigating if ABHs could function for them. The section starts analyzing the embedding of ABHs on circular beams and how this results in the appearance of typical phenomena of periodic systems. After that, an annular ABH is proposed to reduce vibrations in cylindrical shells. The cases of a simply supported shell with an annular ABH indentation and of a periodic simply supported ABH shell with stiffeners are considered. To finish the section, the effects of annular ABHs on sound radiation are investigated in terms of sound power level, radiation efficiency and supersonic intensity. The third part of the thesis is shorter than the previous ones and is devoted to analyzing the transmission loss of a plate with multiple ABH indentations, in the mid-high frequency range. Statistical modal energy distribution analysis is used for that purpose. Here, the ABH plate is not taken as an individual structure but coupled to two air cavities, thus being part of a more complex mechanical system. Throughout the thesis repeated use is made of the Gaussian expansion method (GEM). The GEM refers to taking Gaussian functions as the basis for solving partial differential equations in the framework of the Rayleigh-Ritz method. The GEM closely resembles wavelet approaches but offers some advantages in the case of periodic boundary conditions. A brief overview of the GEM is exposed at the beginning of the thesis and, when necessary, its reformulation for a particular problem is tackled in its corresponding chapter.
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Books on the topic "Black hole structure"

1

Herbert, Gilbert. Speculations on a black hole: Adler & Sullivan, and the planning of the Chicago Auditorium Building. Haifa: Architectural Heritage Research Centre, Technion, 1998.

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1941-, King Jonathan, and Annual Reviews inc, eds. Protein and nucleic acid structure and dynamics. Menlo Park, Calif: Benjamin/Cummings Pub. Co., 1985.

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Carter, Janet M. Selected data for wells and test holes used in structure-contour maps of the Inyan Kara Group, Minnekahta Limestone, Minnelusa Formation, Madison Limestone, and Deadwood Formation in the Black Hills area, South Dakota. Rapid City, S.D: U.S. Dept. of the Interior, U.S. Geological Survey, 1999.

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A, Berezin V., Rubakov V. A, and Semikoz D. V, eds. Quantum gravity: Proceedings of the sixth Moscow seminar : Moscow, Russia, June 12-19, 1995. Singapore: World Scientific, 1998.

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P, Minicozzi William, ed. A course in minimal surfaces. Providence, R.I: American Mathematical Society, 2011.

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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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(Editor), Claudio Teiteboim, and Jorge Zanelli (Editor), eds. Black Holes and the Structure of the Universe. World Scientific Publishing Company, 2000.

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Teitelboim, Claudio, and Jorge Zanelli. Black Holes and the Structure of the Universe. WORLD SCIENTIFIC, 2000. http://dx.doi.org/10.1142/4388.

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Mee, Nicholas. The Cosmic Mystery Tour. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198831860.001.0001.

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The Cosmic Mystery Tour is a brief account of modern physics and astronomy presented in a broad historical and cultural context. The book is attractively illustrated and aimed at the general reader. Part I explores the laws of physics including general relativity, the structure of matter, quantum mechanics and the Standard Model of particle physics. It discusses recent discoveries such as gravitational waves and the project to construct LISA, a space-based gravitational wave detector, as well as unresolved issues such as the nature of dark matter. Part II begins by considering cosmology, the study of the universe as a whole and how we arrived at the theory of the Big Bang and the expanding universe. It looks at the remarkable objects within the universe such as red giants, white dwarfs, neutron stars and black holes, and considers the expected discoveries from new telescopes such as the Extremely Large Telescope in Chile, and the Event Horizon Telescope, currently aiming to image the supermassive black hole at the galactic centre. Part III considers the possibility of finding extraterrestrial life, from the speculations of science fiction authors to the ongoing search for alien civilizations known as SETI. Recent developments are discussed: space probes to the satellites of Jupiter and Saturn; the discovery of planets in other star systems; the citizen science project SETI@Home; Breakthrough Starshot, the project to develop technologies to send spacecraft to the stars. It also discusses the Fermi paradox which argues that we might actually be alone in the cosmos
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Day, C. Radiation from Black Holes, Future Missions to Primitive Bodies and Middle Atmospheric Fine Structures (Advances in Space Research). Elsevier Science Ltd, 1997.

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Book chapters on the topic "Black hole structure"

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Sakellariadou, Maria. "Black Hole Formation from Loops of Cosmic Strings." In The Origin of Structure in the Universe, 175–85. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1705-0_13.

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Dray, Tevian. "Matter at the Horizon of the Schwarzschild Black Hole." In Topological Properties and Global Structure of Space-Time, 73–76. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-3626-4_7.

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Yokosawa, M., and S. Fukazawa. "General Relativistic Magnetohydrodynamic Structure Around a Rotating Black Hole." In Numerical Astrophysics, 223–24. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4780-4_71.

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Kazanas, Demosthenes. "X-Ray Binary Phenomenology and Their Accretion Disk Structure." In The Formation and Disruption of Black Hole Jets, 207–25. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-10356-3_8.

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Sussman, Roberto A. "A Simple Model of a Non-Asymptotically Flat Schwarzschild Black Hole." In Topological Properties and Global Structure of Space-Time, 271–82. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-3626-4_20.

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Ahmed Rizwan, C. L., A. Naveena Kumar, and K. S. Ananthram. "Effect of Global Monopole on the Microscopic Structure of RN-AdS Black Hole." In Springer Proceedings in Physics, 81–85. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6292-1_10.

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Kapoor, Ramesh Chander. "Effect of Dynamical Friction on the Escape of a Supermassive Black Hole Ejected from the Center of a Galaxy." In Structure and Evolution of Active Galactic Nuclei, 573–77. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4562-3_52.

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Wang, D. X. "Effects of the Blandford-Znajek Process on Evolution of Radial Structure of Black Hole Accretion Disks." In Stellar Astrophysics, 243–48. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-010-0878-5_28.

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Chruściel, Piotr T. "Black Holes." In The Conformal Structure of Space-Time, 61–102. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-45818-2_3.

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Marsh, David J. E., and Sebastian Hoof. "Astrophysical Searches and Constraints." In The Search for Ultralight Bosonic Dark Matter, 73–122. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95852-7_3.

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AbstractStarting from the evidence that dark matter (DM) indeed exists and permeates the entire cosmos, various bounds on its properties can be estimated. Beginning with the cosmic microwave background and large-scale structure, we summarize bounds on the ultralight bosonic dark matter (UBDM) mass and cosmic density. These bounds are extended to larger masses by considering galaxy formation and evolution and the phenomenon of black hole superradiance. We then discuss the formation of different classes of UBDM compact objects including solitons/axion stars and miniclusters. Next, we consider astrophysical constraints on the couplings of UBDM to Standard Model particles, from stellar cooling (production of UBDM) and indirect searches (decays or conversion of UBDM). Throughout, there are short discussions of “hints and opportunities” in searching for UBDM in each area.
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Conference papers on the topic "Black hole structure"

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BRETÓN, NORA. "HORIZON STRUCTURE OF BORN-INFELD BLACK HOLE." In Proceedings of 2002 International Conference. WORLD SCIENTIFIC, 2006. http://dx.doi.org/10.1142/9789812772732_0008.

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Volonteri, Marta. "Supermassive black hole mergers and cosmological structure formation." In LASER INTERFEROMETER SPACE ANTENNA: 6th International LISA Symposium. AIP, 2006. http://dx.doi.org/10.1063/1.2405022.

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Rannu, Kristina. "Internal structure of Maxwell-Gauss-Bonne black hole." In The XIXth International Workshop on High Energy Physics and Quantum Field Theory. Trieste, Italy: Sissa Medialab, 2011. http://dx.doi.org/10.22323/1.104.0079.

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Bini, Donato, and Andrea Geralico. "Extended bodies with structure up to the quadrupole in black hole spacetimes." In Proceedings of the MG14 Meeting on General Relativity. WORLD SCIENTIFIC, 2017. http://dx.doi.org/10.1142/9789813226609_0488.

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Meier, David L. "Jet power and jet suppression: The role of disk structure and black hole rotation." In RELATIVISTIC ASTROPHYSICS: 20th Texas Symposium. AIP, 2001. http://dx.doi.org/10.1063/1.1419586.

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Pariev, Vladimir I., and Benjamin C. Bromley. "Line emission from an accretion disk around black hole: effects of the disk structure." In Accretion processes in astrophysical systems: Some like it hot! - eigth astrophysics conference. AIP, 1998. http://dx.doi.org/10.1063/1.55906.

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Shidatsu, Megumi, Yoshihiro Ueda, Takafumi Hori, Chris Done, and Satoshi Nakahira. "Wide-band X-ray Studies of Inner Disc Structure in Galactic Black Hole Binaries." In Swift: 10 Years of Discovery. Trieste, Italy: Sissa Medialab, 2015. http://dx.doi.org/10.22323/1.233.0162.

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Bolokhov, S. V., and V. D. Ivashchuk. "Global structure of black hole and brane solutions in a multidimensional model with anisotropic fluid." In Twelfth Asia-Pacific International Conference on Gravitation, Astrophysics, and Cosmology. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814759816_0070.

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HE, Pu, Jun-jie ZHU, Xiao-zhu SUN, Hong-li JI, and Jin-hao QIU. "Energy Focusing Effect Of A Novel Acoustic Black Hole Absorber On Flexural Waves In Box-Type Structure." In 2020 15th Symposium on Piezoelectrcity, Acoustic Waves and Device Applications (SPAWDA). IEEE, 2021. http://dx.doi.org/10.1109/spawda51471.2021.9445429.

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Cornean, Horia, Sergey Sorokin, and Benjamin Støttrup. "ACOUSTIC BLACK HOLE PROFILE OPTIMIZATION." In XI International Conference on Structural Dynamics. Athens: EASD, 2020. http://dx.doi.org/10.47964/1120.9202.20000.

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Reports on the topic "Black hole structure"

1

Liedahl, D., and C. Mauche. Structure and Spectroscopy of Black Hole Accretion Disks. Office of Scientific and Technical Information (OSTI), February 2005. http://dx.doi.org/10.2172/918406.

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DeAnna, Dixon, and Hodo Wayne. Finite element analysis of quoin block deterioration and load transfer mechanisms in miter gates : pintle and pintle connections. Engineer Research and Development Center (U.S.), June 2021. http://dx.doi.org/10.21079/11681/40842.

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The U.S. Army Corps of Engineers (USACE) currently operates and maintains approximately 193 commercially active lock sites with 239 locks and dams spanning nearly 12,000 miles. These networks of water channels are used to transport 600 million tons of domestic cargo, generating $405 billion in revenue annually. Nearly 60% of these structures in operation are over 50 years old and have reached design life. A failure of the miter gates could result in a major negative impact on the economy and on the ability to maintain flood control. Administrators need recommendations to better prioritize maintenance and repair of the USACE miter gates. This work investigated the influence of miter gate’s quoin block degradation on load transfer to the pintle and/or pintle connections. Results of finite element analysis are reported for the quoin block degradation simulated levels of 0%, 25%, 50%, and 75%. The parametric study shows the overstressed regions are the pintle neck and bolt-hole regions. To improve pintle designs so they may better mitigate detrimental environmental based deterioration effects, this work recommends (1) increasing the thickness of the bolt-hole connection region and (2) adding ribbing reinforcement around the neck area of the pintle.
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