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Journal articles on the topic 'Collapse models'

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Author: Grafiati

Published: 11 March 2023

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1

Halevi, Goni, Belinda Wu, Philipp Mösta, Ore Gottlieb, Alexander Tchekhovskoy, and David R. Aguilera-Dena. "Density Profiles of Collapsed Rotating Massive Stars Favor Long Gamma-Ray Bursts." Astrophysical Journal Letters 944, no. 2 (February 1, 2023): L38. http://dx.doi.org/10.3847/2041-8213/acb702.

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Abstract Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows—jets—that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to propagate through and break out of. Most previous studies have used simple power laws or pre-collapse models for massive stars. However, the relevant stellar profile for lGRB models is in fact that of a star after its core has collapsed to form a compact object. To self-consistently compute such a stellar profile, we use the open-source code GR1D to simulate the core-collapse process for a suite of low-metallicity rotating massive stellar progenitors that have undergone chemically homogeneous evolution. Our models span a range of zero-age main-sequence (ZAMS) masses: M ZAMS = 13, 18, 21, 25, 35, 40, and 45M ☉. All of these models, at the onset of core-collapse, feature steep density profiles, ρ ∝ r −α , with α ≈ 2.5, which would result in jets that are inconsistent with lGRB observables. We follow the collapses of four of the seven models until they form black holes (BHs) and the other three models until they form proto-neutron stars (PNSs). We find, across all models, that the density profile outside the newly formed BH or PNS is well represented by a flatter power law with α ≈ 1.35–1.55. Such flat density profiles are conducive to the successful formation and breakout of BH-powered jets and are, in fact, required to reproduce observable properties of lGRBs. Future models of lGRBs should be initialized with shallower post-collapse stellar profiles, like those presented here, instead of the much steeper pre-collapse profiles that are typically used.

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2

Pavlík, Václav, and Ladislav Šubr. "The hunt for self-similar core collapse." Astronomy & Astrophysics 620 (December 2018): A70. http://dx.doi.org/10.1051/0004-6361/201833854.

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Context. Core collapse is a prominent evolutionary stage of self-gravitating systems. In an idealised collisionless approximation, the region around the cluster core evolves in a self-similar way prior to the core collapse. Thus, its radial density profile outside the core can be described by a power law, ρ ∝ r−α. Aims. We aim to find the characteristics of core collapse in N-body models. In such systems, a complete collapse is prevented by transferring the binding energy of the cluster to binary stars. The contraction is, therefore, more difficult to identify. Methods. We developed a method that identifies the core collapse in N-body models of star clusters based on the assumption of their homologous evolution. Results. We analysed different models (equal- and multi-mass), most of which exhibit patterns of homologous evolution, yet with significantly different values of α : the equal-mass models have α ≈ 2.3, which agrees with theoretical expectations, the multi-mass models have α ≈ 1.5 (yet with larger uncertainty). Furthermore, most models usually show sequences of separated homologous collapses with similar properties. Finally, we investigated a correlation between the time of core collapse and the time of formation of the first hard binary star. The binding energy of such a binary usually depends on the depth of the collapse in which it forms, for example from 100 kT to 104 kT in the smallest equal-mass to the largest multi-mass model, respectively. However, not all major hardenings of binaries happened during the core collapse. In the multi-mass models, we see large transfers of binding energy of ∼104 kT to binaries that occur on the crossing timescale and outside of the periods of the homologous collapses.

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3

Reznik, Рetro, Sergiy Grebenchuk, Roman Koreniev, and Vitaliy Bondarenko. "Research of the specific steel shells progressive collapse prevention." ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 1, no. 52 (July 5, 2019): 58–64. http://dx.doi.org/10.26906/znp.2019.52.1676.

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The article deals with coatings in the form of the specific steel shells. After a detailed analysis certain number of accidentsand collapses, these collapses can be classified as “progressive” collapse. The main purpose of the article is the developmentof design algorithms for evaluation of the stress-strain state and preventing the progressive collapse of the specific steelshells. The method of prevention progressive collapse has been developed in the form of a constructive modernization.The comparative finite-element analysis of the strained-strain state of the specific shells original models, models of discretecontinualribbed shells (with constructive upgrading) and models of solid ribbed shells has been carried out. From the analysisresults it can be concluded that the proposed modernization method can be considered as one of the possible options forpreventing progressive collapses and increasing the bearing capacity of specific steel shells.

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4

Ott, Christian D., Erik Schnetter, Adam Burrows, Eli Livne, Evan O'Connor, and Frank Löffler. "Computational models of stellar collapse and core-collapse supernovae." Journal of Physics: Conference Series 180 (July 1, 2009): 012022. http://dx.doi.org/10.1088/1742-6596/180/1/012022.

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5

Ghirardi, Gian Carlo, and Raffaele Romano. "Collapse models and perceptual processes." Journal of Physics: Conference Series 504 (April 14, 2014): 012022. http://dx.doi.org/10.1088/1742-6596/504/1/012022.

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6

Dowker, Fay, and Isabelle Herbauts. "Simulating causal wavefunction collapse models." Classical and Quantum Gravity 21, no. 12 (May 19, 2004): 2963–79. http://dx.doi.org/10.1088/0264-9381/21/12/011.

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7

Thompson, M. C. "Rapidly Rotating Core-Collapse Models." Publications of the Astronomical Society of Australia 6, no. 2 (1985): 214–16. http://dx.doi.org/10.1017/s1323358000018130.

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AbstractVery few (if any at all) three dimensional models of the final evolutionary stages of a star’s life have appeared in the literature. Such models may be important if the stellar core maintains sufficient rotational energy during it’s lifetime so that when collapse finally occurs, the increase of rotational energy to gravitational energy, may lead to a non-axisymmetric instability.A sequence of core collapse models with decreasing rotation rate is considered. These models were calculated using a three dimensional, post-Newtonian, hydrodynamical, numerical code. The results show that for high precollapse rotational energies the core can become unstable resulting in the formation of what resemble ‘spiral arms’. Unfortunately, because of limits on computer time, the calculations had to be discontinued shortly after this development occurred.

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8

Jadamec, Margarete A., Donald L. Turcotte, and Peter Howell. "Analytic models for orogenic collapse." Tectonophysics 435, no. 1-4 (May 2007): 1–12. http://dx.doi.org/10.1016/j.tecto.2007.01.007.

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9

Hartmann, Lee, Nuria Calvet, and Alan Boss. "Sheet Models of Protostellar Collapse." Astrophysical Journal 464 (June 1996): 387. http://dx.doi.org/10.1086/177330.

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10

Brax, Ph, R. Rosenfeld, and D. A. Steer. "Spherical collapse in chameleon models." Journal of Cosmology and Astroparticle Physics 2010, no. 08 (August 23, 2010): 033. http://dx.doi.org/10.1088/1475-7516/2010/08/033.

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11

Sugimoto, Daiichiro. "Gaseous Models." Symposium - International Astronomical Union 113 (1985): 207–18. http://dx.doi.org/10.1017/s0074180900147394.

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We can understand physics of self-gravitating system in terms of gaseous models in so far that their global natures and effects of self-gravity are concerned. Here summarized what are known in idealized gaseous models. They include gravothermal collapse/expansion in linear and non-linear regimes, and post-collapse evolution with gravothermal oscillation. Also discussed are their relations with discrete system and with treatment in statistical mechanics.

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12

Olsen, Anna H., Thomas H. Heaton, and John F. Hall. "Characterizing Ground Motions that Collapse Steel Special Moment-Resisting Frames or Make Them Unrepairable." Earthquake Spectra 31, no. 2 (May 2015): 813–40. http://dx.doi.org/10.1193/102612eqs318m.

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This work applies 64,765 simulated seismic ground motions to four models each of 6- or 20-story, steel special moment-resisting frame buildings. We consider two vector intensity measures and categorize the building response as “collapsed,” “unrepairable,” or “repairable.” We then propose regression models to predict the building responses from the intensity measures. The best models for “collapse” or “unrepairable” use peak ground displacement and velocity as intensity measures, and the best models predicting peak interstory drift ratio, given that the frame model is “repairable,” use spectral acceleration and epsilon ( ∊) as intensity measures. The more flexible frame is always more likely than the stiffer frame to “collapse” or be “unrepairable.” A frame with fracture-prone welds is substantially more susceptible to “collapse” or “unrepairable” damage than the equivalent frame with sound welds. The 20-story frames with fracture-prone welds are more vulnerable to P-delta instability and have a much higher probability of collapse than do any of the 6-story frames.

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Piccirilli, María Pía, Gabriel León, Susana J. Landau, Micol Benetti, and Daniel Sudarsky. "Constraining quantum collapse inflationary models with current data: The semiclassical approach." International Journal of Modern Physics D 28, no. 02 (January 2019): 1950041. http://dx.doi.org/10.1142/s021827181950041x.

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The hypothesis of the self-induced collapse of the inflaton wave function was introduced as a candidate for the physical process responsible for the emergence of inhomogeneity and anisotropy at all scales. In particular, we consider different proposal for the precise form of the dynamics of the inflaton wave function: (i) the GRW-type collapse schemes proposals based on spontaneous individual collapses which generate nonvanishing expectation values of various physical quantities taken as ansatz modifications of the standard inflationary scenario; (ii) the proposal based on a Continuous Spontaneous Localization (CSL) type modification of the Schrödinger evolution of the inflaton wave function, based on a natural choice of collapse operator. We perform a systematic analysis within the semi-classical gravity approximation, of the standing of those models considering a full quasi-de Sitter expansion scenario. We note that the predictions for the Cosmic Microwave Background (CMB) temperature and polarization spectrum differ slightly from those of the standard cosmological model. We also analyze these proposals with a Bayesian model comparison using recent CMB and Baryonic Acoustic Oscillations (BAO) data. Our results show a moderate preference of the joint CMB and BAO data for one of the studied collapse schemes model over the [Formula: see text]CDM one, while there is no preference when only CMB data are considered. Additionally, analysis using CMB data provide the same Bayesian evidence for both the CSL and Standard Models, i.e. the data have no preference between the simplicity of the LCDM model and the complexity of the collapse scenario.

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14

Jones, C., G. Gasbarri, and A. Bassi. "Mass-coupled relativistic spontaneous collapse models." Journal of Physics A: Mathematical and Theoretical 54, no. 29 (June 24, 2021): 295306. http://dx.doi.org/10.1088/1751-8121/abf871.

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15

Nolan, Louise V. "Cylindrically Symmetric Models of Gravitational Collapse." Irish Mathematical Society Bulletin 0060 (2007): 32. http://dx.doi.org/10.33232/bims.0060.32.

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16

Adler, Stephen L., and Angelo Bassi. "Collapse models with non-white noises." Journal of Physics A: Mathematical and Theoretical 40, no. 50 (November 28, 2007): 15083–98. http://dx.doi.org/10.1088/1751-8113/40/50/012.

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17

Dowker, Fay, and Joe Henson. "Spontaneous Collapse Models on a Lattice." Journal of Statistical Physics 115, no. 5/6 (June 2004): 1327–39. http://dx.doi.org/10.1023/b:joss.0000028061.97843.84.

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18

TALEB, M., S. AHMED-ZAID, and W. W. PRICE. "INDUCTION MACHINE MODELS NEAR VOLTAGE COLLAPSE." Electric Machines & Power Systems 25, no. 1 (January 1997): 15–27. http://dx.doi.org/10.1080/07313569708955721.

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19

Nomoto, Ken'ichi. "Core Collapse Supernova Models and Nucleosynthesis." Proceedings of the International Astronomical Union 9, S296 (January 2013): 27–36. http://dx.doi.org/10.1017/s1743921313009198.

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AbstractAfter the Big Bang, production of heavy elements in the early Universe takes place in the first stars and their supernova explosions. The nature of the first supernovae, however, has not been well understood. The signature of nucleosynthesis yields of the first supernovae can be seen in the elemental abundance patterns observed in extremely metal-poor stars. Interestingly, those abundance patterns show some peculiarities relative to the solar abundance pattern, which should provide important clues to understanding the nature of early generations of supernovae. We review the recent results of the nucleosynthesis yields of massive stars. We examine how those yields are affected by some hydrodynamical effects during the supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars.

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20

Martínez-Pinedo, Gabriel, Matthias Liebendörfer, and Dieter Frekers. "Nuclear input for core-collapse models." Nuclear Physics A 777 (October 2006): 395–423. http://dx.doi.org/10.1016/j.nuclphysa.2006.02.014.

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21

Adler, R. J., J. D. Bjorken, P. Chen, and J. S. Liu. "Simple analytical models of gravitational collapse." American Journal of Physics 73, no. 12 (December 2005): 1148–59. http://dx.doi.org/10.1119/1.2117187.

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22

Bedingham, D. J., and O. J. E. Maroney. "Time Reversal Symmetry and Collapse Models." Foundations of Physics 47, no. 5 (April 8, 2017): 670–96. http://dx.doi.org/10.1007/s10701-017-0084-5.

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23

Thapa, Dilli Ram. "Use of two dimensional electrical resistivity tomography (2D- ERT) synthetic modelling to detect collapse masses." Journal of Nepal Geological Society 60 (September 16, 2020): 139–45. http://dx.doi.org/10.3126/jngs.v60i0.31250.

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The presence of collapse masses in the subsurface causes severe problems in the geotechnical design activities. In this study, two dimensional Electrical Resistivity Tomography (2D-ERT) synthetic modelling techniques were used to detect collapse masses commonly found in the river bank. Two dimensional (2D) resistivity models are first created utilizing prior information of collapsed masses in the river bank and afterward inverted to reconstruct the resistivity distribution in the subsurface. The resulting two dimensional models exhibits that collapsed masses can be better detected particularly at low resistivity noise level (2%) than the high noise levels (5% and 10%). The models are particularly very useful prior to executing the field investigations in the river bank sites and furnish the subsurface geology as well as the successful interpretation of the results withconfidence.

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24

Felicetti, Simone, and Alexandre Boité. "Observing the Spectral Collapse of Two-Photon Interaction Models." Proceedings 12, no. 1 (July 22, 2019): 41. http://dx.doi.org/10.3390/proceedings2019012041.

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Until very recently, two-photon interaction processes have been considered only as arising from second- or higher-order effects in driven systems, and so limited to extremely small coupling strengths. However, a variety of novel physical phenomena emerges in the strong and ultrastrong coupling regimes. Strikingly, for a critical value of the coupling strength the discrete spectrum collapses into a continuous band. In this extended abstract, we discuss recent proposals to implement genuine two-photon interactions in an undriven solid-state system, in the framework of circuit QED. In particular, we review counterintuitive spectral features of two-photon interaction models and we show how the onset of the spectral collapse can be observed in feasible scattering experiments.

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25

Zhang, Zhuo Qun, You Xin Lin, and Hong Nan Li. "Wind-Induced Progressive Collapsed Performance of Cup-Type Transmission Tower-Line System." Applied Mechanics and Materials 353-356 (August 2013): 2392–96. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.2392.

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The Cup-type transmission tower-line system was a classic representative of high voltage electric power carrier, which was an important lifeline project. However, it frequently collapsed under different environmental loadings, especially strong wind. In this work, four tower five line finite element models simulated wind-induced progressive collapse process by birth-to-death element technique in ABAQUS/Explicit. The numerical simulation results demonstrated that this application could describe the structural collapse performance clearly and effectively and transmission tower-line system collapse path depended on the number, position and last deformation of damage elements.

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Xu, Qinghu, Xuezhi Zhen, Yu Zhang, Mengjun Han, and Wenkang Zhang. "Numerical Simulation Study of Progressive Collapse of Reinforced Concrete Frames with Masonry Infill Walls under Blast Loading." Modelling and Simulation in Engineering 2022 (November 11, 2022): 1–16. http://dx.doi.org/10.1155/2022/1781415.

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The influence of masonry infill walls on the progressive collapse performance of reinforced concrete (RC) frame structures was investigated in this paper, using a nonlinear dynamic analysis approach. Based on ANSYS/LS-DYNA finite element software, two finite element models of RC frame structures with and without masonry infilled walls were established. Then, the collapse modes of the two RC frame structure models were analyzed for different scaled distance blast loads, different locations of column damage, and different span numbers. The results show that with the increase of explosive amount, the collapse degree of the structure is more serious in the same time. Under the condition of destroying the outermost central column, the degree of progressive collapse of the RC frame model with infilled walls in the same time is lower than that of the RC frame model without infilled walls. The RC frame model with infilled walls is more resistant to collapse when the outermost side columns are damaged. With the increase of span number, the structure is more likely to be damaged and collapsed.

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27

Wang, Yi Xuan, and Lei Huang. "Research on Numerical Model for Earthquake Induced Progressive Collapse of High-Rise Buildings." Applied Mechanics and Materials 716-717 (December 2014): 223–26. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.223.

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Progressive collapse is defined as the collapse of the whole building due to local weak stories or weak zones. In this paper, collapse should theoretically be avoided for any building under any earthquake, it is necessary to study the collapse behavior of buildings to acquire a better understanding of the collapse mechanism and to find efficient methods to prevent it. The collapse process highly depends on the feature of the whole structural system, so numerical simulation becomes a major method to study it. Based on the finite element method, by selecting the appropriate cell death and cell contact algorithm criterion can better simulate the structure collapsed in an earthquake under the continuity of the whole process of destruction, to help understand the causes and mechanism of structural damage. The real buildings are analyzed to study the failure mechanism of the structure. The models proposed are reasonable to study the seismic collapse mechanism of high-rise buildings.

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Kołodziejczyk, Leszek Aleksander, and Neil Thapen. "The polynomial and linear hierarchies in models where the weak pigeonhole principle fails." Journal of Symbolic Logic 73, no. 2 (June 2008): 578–92. http://dx.doi.org/10.2178/jsl/1208359061.

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AbstractWe show, under the assumption that factoring is hard, that a model of PV exists in which the polynomial hierarchy does not collapse to the linear hierarchy; that a model of exists in which NP is not in the second level of the linear hierarchy; and that a model of exists in which the polynomial hierarchy collapses to the linear hierarchy.Our methods are model-theoretic. We use the assumption about factoring to get a model in which the weak pigeonhole principle fails in a certain way, and then work with this failure to obtain our results.As a corollary of one of the proofs, we also show that in the failure of WPHP (for definable relations) implies that the strict version of PH does not collapse to a finite level.

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Cooling, Meghan, Stephen Hartley, Dalice A. Sim, and Philip J. Lester. "The widespread collapse of an invasive species: Argentine ants ( Linepithema humile ) in New Zealand." Biology Letters 8, no. 3 (November 30, 2011): 430–33. http://dx.doi.org/10.1098/rsbl.2011.1014.

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Synergies between invasive species and climate change are widely considered to be a major biodiversity threat. However, invasive species are also hypothesized to be susceptible to population collapse, as we demonstrate for a globally important invasive species in New Zealand. We observed Argentine ant populations to have collapsed in 40 per cent of surveyed sites. Populations had a mean survival time of 14.1 years (95% CI = 12.9–15.3 years). Resident ant communities had recovered or partly recovered after their collapse. Our models suggest that climate change will delay colony collapse, as increasing temperature and decreasing rainfall significantly increased their longevity, but only by a few years. Economic and environmental costs of invasive species may be small if populations collapse on their own accord.

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TEDDER, ANDREW. "AXIOMS FOR FINITE COLLAPSE MODELS OF ARITHMETIC." Review of Symbolic Logic 8, no. 3 (November 18, 2014): 529–39. http://dx.doi.org/10.1017/s1755020314000355.

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AbstractThe collapse models of arithmetic are inconsistent, nontrivial models obtained from ℕ and set out in the Logic of Paradox (LP). They are given a general treatment by Priest (Priest, 2000). Finite collapse models are decidable, and thus axiomatizable, because finite. LP, however, is ill-suited to normal axiomatic reasoning, as it invalidates Modus Ponens, and almost all other usual conditional inferences. I set out a logic, A3, first given by Avron (Avron, 1991), and give a first order axiom system for the finite collapse models. I present some standard arithmetical axioms in addition to a cyclic axiom and prove that these axioms are sound and complete for the cyclic models, reporting a similar result for the heap models. The state of the situation for the each of the kinds of infinite collapse model is, however, left an open question.

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FRYER, CHRIS L. "STELLAR COLLAPSE." International Journal of Modern Physics D 12, no. 10 (December 2003): 1795–835. http://dx.doi.org/10.1142/s0218271803004298.

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The collapse of massive stars have been used to explain many of the largest outbursts known to mankind, from supernovae to hypernovae to gamma-ray bursts. These explosions differ in their level of asymmetry and the spectral energy of the photons they emit. It is likely that such a wide range in the nature of these explosions requires more than one explosion mechanism to extract the gravitational potential energy released during the collapse. Three major classes of mechanisms have been proposed: neutrino-driven, magnetic-field driven, collapsar (black hole accretion disk) driven. This review discusses each mechanism in turn, discussing the current state-of-the-art calculations along with their observational predictions. We conclude with a summary of the current observational constraints on these models.

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Vinante, Andrea. "Testing spontaneous collapse models with mechanical experiments." Journal of Physics: Conference Series 1275 (September 2019): 012015. http://dx.doi.org/10.1088/1742-6596/1275/1/012015.

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Adler, Stephen L., Angelo Bassi, and Sandro Donadi. "On spontaneous photon emission in collapse models." Journal of Physics A: Mathematical and Theoretical 46, no. 24 (June 3, 2013): 245304. http://dx.doi.org/10.1088/1751-8113/46/24/245304.

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Dove, Chris, and Evan J. Squires. "Symmetric versions of explicit wavefunction collapse models." Foundations of Physics 25, no. 9 (September 1995): 1267–82. http://dx.doi.org/10.1007/bf02055332.

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Bedingham, Daniel. "Time symmetry in wave function collapse models." Journal of Physics: Conference Series 626 (July 3, 2015): 012007. http://dx.doi.org/10.1088/1742-6596/626/1/012007.

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36

Mariani, Mauro, Gabriel R. Bengochea, and Gabriel León. "Inflationary gravitational waves in collapse scheme models." Physics Letters B 752 (January 2016): 344–51. http://dx.doi.org/10.1016/j.physletb.2015.11.069.

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37

Bengochea, Gabriel R., and Gabriel León. "Novel vacuum conditions in inflationary collapse models." Physics Letters B 774 (November 2017): 338–50. http://dx.doi.org/10.1016/j.physletb.2017.09.085.

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Donadi, Sandro, Angelo Bassi, Catalina Curceanu, Antonio Di Domenico, and Beatrix C. Hiesmayr. "Are Collapse Models Testable via Flavor Oscillations?" Foundations of Physics 43, no. 7 (May 1, 2013): 813–44. http://dx.doi.org/10.1007/s10701-013-9720-x.

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Chang, Chia-Chun, Wolung Lee, and Kin-Wang Ng. "Spherical collapse models with clustered dark energy." Physics of the Dark Universe 19 (March 2018): 12–20. http://dx.doi.org/10.1016/j.dark.2017.10.006.

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40

Curceanu, Catalina, Raffaele Del Grande, Matthias Laubenstein, and Kristian Piscicchia. "Collapse models tested in the LNGS underground laboratories." International Journal of Quantum Information 17, no. 08 (December 2019): 1941011. http://dx.doi.org/10.1142/s0219749919410119.

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Collapse models consist in dynamical reformulations of the standard quantum mechanics aiming to solve the measurement problem. The standard Schrödinger dynamics is modified with the introduction of nonlinear and stochastic terms, which induce the wave function collapse in space. Collapse models predict slight deviations from the standard quantum mechanics predictions, in particular the emission of a “spontaneous radiation”, which we explored to set the most stringent limits on the collapse models parameters in a broad range. To this end, the X-ray emission data collected by the IGEX collaboration are analyzed and compared with the spectrum of the spontaneous photon emission process predicted by the theories. The results of the data analyses, and the ongoing experimental efforts will be presented.

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Aloy, M. Á., and M. Obergaulinger. "Magnetorotational core collapse of possible GRB progenitors – II. Formation of protomagnetars and collapsars." Monthly Notices of the Royal Astronomical Society 500, no. 4 (October 22, 2020): 4365–97. http://dx.doi.org/10.1093/mnras/staa3273.

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ABSTRACT We assess the variance of the post-collapse evolution remnants of compact, massive, low-metallicity stars, under small changes in the degrees of rotation and magnetic field of selected pre-supernova cores. These stellar models are commonly considered progenitors of long gamma-ray bursts. The fate of the protoneutron star (PNS) formed after the collapse, whose mass may continuously grow due to accretion, critically depends on the poloidal magnetic field strength at bounce. Should the poloidal magnetic field be sufficiently weak, the PNS collapses to a black hole (BH) within a few seconds. Models on this evolutionary track contain promising collapsar engines. Poloidal magnetic fields smooth over large radial scales (e.g. dipolar fields) or slightly augmented with respect to the original pre-supernova core yield long-lasting PNSs. In these models, BH formation is avoided or staved off for a long time, hence, they may produce protomagnetars (PMs). Some of our PM candidates have been run for $\lesssim 10\,$ s after core bounce, but they have not entered the Kelvin–Helmholtz phase yet. Among these models, some display episodic events of spin-down during which we find properties broadly compatible with the theoretical expectations for PMs ($M_\rm {\small PNS}\approx 1.85{-}2.5\, \mathrm{M}_{\odot }$, $\bar{P}_\rm {\small PNS}\approx 1.5 {-} 4\,$ ms, and $b^{\rm surf}_\rm {\small PNS}\lesssim 10^{15}\,$ G) and their very collimated supernova ejecta have nearly reached the stellar surface with (still growing) explosion energies $\gtrsim {2} \times 10^{51}\, \textrm {erg}$.

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Tilloy, Antoine, and Howard M. Wiseman. "Non-Markovian wave-function collapse models are Bohmian-like theories in disguise." Quantum 5 (November 29, 2021): 594. http://dx.doi.org/10.22331/q-2021-11-29-594.

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Spontaneous collapse models and Bohmian mechanics are two different solutions to the measurement problem plaguing orthodox quantum mechanics. They have, a priori nothing in common. At a formal level, collapse models add a non-linear noise term to the Schrödinger equation, and extract definite measurement outcomes either from the wave function (e.g. mass density ontology) or the noise itself (flash ontology). Bohmian mechanics keeps the Schrödinger equation intact but uses the wave function to guide particles (or fields), which comprise the primitive ontology. Collapse models modify the predictions of orthodox quantum mechanics, whilst Bohmian mechanics can be argued to reproduce them. However, it turns out that collapse models and their primitive ontology can be exactly recast as Bohmian theories. More precisely, considering (i) a system described by a non-Markovian collapse model, and (ii) an extended system where a carefully tailored bath is added and described by Bohmian mechanics, the stochastic wave-function of the collapse model is exactly the wave-function of the original system conditioned on the Bohmian hidden variables of the bath. Further, the noise driving the collapse model is a linear functional of the Bohmian variables. The randomness that seems progressively revealed in the collapse models lies entirely in the initial conditions in the Bohmian-like theory. Our construction of the appropriate bath is not trivial and exploits an old result from the theory of open quantum systems. This reformulation of collapse models as Bohmian theories brings to the fore the question of whether there exists `unromantic' realist interpretations of quantum theory that cannot ultimately be rewritten this way, with some guiding law. It also points to important foundational differences between `true' (Markovian) collapse models and non-Markovian models.

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Zheng, Zhe, Wenjie Liao, Jiarui Lin, Yucheng Zhou, Chi Zhang, and Xinzheng Lu. "Digital Twin-Based Investigation of a Building Collapse Accident." Advances in Civil Engineering 2022 (March 14, 2022): 1–13. http://dx.doi.org/10.1155/2022/9568967.

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The collapse of engineering structures can cause significant casualties and have negative social effects. Collapse accident investigation can elucidate the potential causes and mechanisms of the collapse accident, thus remediating future structural collapse and enhancing the resilience. However, there are some obstacles to investigating complicated collapse accidents using conventional methods. For example, the out-syncs between on-site investigation and simulation analysis are intractable and can make discovering the cause of collapse accidents difficult. Hence, a digital twin-based investigation method for collapse accidents was proposed. First, basic virtual digital building models are established using real-world information. Then, after mapping the data from the real world into the virtual space, the corresponding highly realistic multistage models before and after the building collapse accident are constructed and synchronized. Using the digital twin method, investigators with multidisciplinary knowledge can efficiently integrate, update, and check the models. Finally, the potential collapse mechanism was revealed with the assistance of the corresponding models. To demonstrate the effectiveness of the proposed digital twin-based investigation method, a real collapse accident investigation is utilized as an example. These results validated our method.

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Aguilar, L. A., D. Merritt, and M. Duncan. "Cold Collapse as a Way of Making Elliptical Galaxies." Symposium - International Astronomical Union 127 (1987): 519–20. http://dx.doi.org/10.1017/s0074180900186036.

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SummaryWe investigate whether dissipationless collapse starting from very cold, non-rotating initial conditions can produce objects resembling real elliptical galaxies. We also study the effect of various initial geometries on the shape of the final object. Collapses that are initially very cold (2T/W < 0.1) are different from warmer collapses, due to the presence of a dynamical instability associated with clumping of nearly-radial orbits (Polyachenko 1981). This instability can produce very elongated bars (1.6 to 2.1 axis ratio) from spherical initial conditions. the instability is also present in models evolved from oblate and triaxial initial conditions. Warm collapses tend to preserve their initial shapes. Cold initial conditions produce objects whose surface density profiles are well fit by a de-Vaucouleurs law; warm collapses, on the other hand, produce a core-halo profile. A large collapse factor seems necessary to produce objects resembling real galaxies; the same collapse factor guarantees the presence of the radial orbit instability. It thus appears that initial flattening is not crucial for producing prolate or nearly prolate galaxies. Oblate galaxies, on the contrary, seem very difficult to form, unless extremely flattened initial conditions are invoked. Preliminary experiments suggest that these results are not changed by realistic amounts of angular momentum.

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Wang, Wei, Nana Zhang, Leiming Wang, Ziyi Wang, and Donghui Ma. "A Study of Influence Distance and Road Safety Avoidance Distance from Postearthquake Building Debris Accumulation." Advances in Civil Engineering 2020 (February 21, 2020): 1–17. http://dx.doi.org/10.1155/2020/7034517.

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To study the influence of the debris accumulation caused by the continuous collapse of the postearthquake building structure on the avoidance distance of the road red line, taking the typical masonry structures of three stories, five stories, and seven stories as examples, this study simulates the process of sloughing collapse and the positive and negative collapse along the Z axis of the building structure under 28 different seismic conditions in details. Taking “the flying stones” into consideration, this study divides the influence distance of the collapsed building structure under earthquakes into (a) the safety distance during earthquakes and (b) the main influence distance of the debris accumulation after the earthquake. In this study, two types of movement laws of flying stones are analyzed statistically first. Then, the statistical analysis and hypothesis testing are carried out on the main influence distance of all the debris accumulation using the influence width coefficient, and the main influence distance distribution probability models of the debris accumulation of the collapsed building structure under earthquake excitation are established. The distribution models include the gamma distribution and the extreme value type III along the Z axis and the normal distribution probability model along the X axis. Finally, a simplified calculation table of the influence distance of collapsed building structures is established. It provides a scientific basis for the safe control distance of buildings to avoid the road red line and for the minimum distance between the buildings and people after a destructive earthquake.

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Goncalves Da Silva, Eric, and Philippe Parnaudeau. "Comparison of multiphase models for computing shock-induced bubble collapse." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 8 (November 22, 2019): 3845–77. http://dx.doi.org/10.1108/hff-05-2019-0399.

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Purpose The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both the free-ﬁeld case and the collapse near a wall are investigated. Simulations are performed on both two- and three-dimensional conﬁgurations. The main phenomena involved in the bubble collapse are illustrated. A focus on the maximum pressure reached during the collapse is proposed. Design/methodology/approach Simulations are performed using an inviscid compressible homogeneous solver based on different systems of equations. It consists in solving different mixture or phasic conservation laws and a transport-equation for the gas volume fraction. Three-dimensional conﬁgurations are considered for which an eﬃcient massively parallel strategy was developed. The code is based on a finite volume discretization for which numerical fluxes are computed with a Harten, Lax, Van Leer, Contact (HLLC) scheme. Findings The comparison of three multiphase models is proposed. It is shown that a simple four-equation model is well-suited to simulate such strong shock-bubble interaction. The three-dimensional collapse near a wall is investigated. It is shown that the intensity of pressure peaks on the wall is drastically increased (more than 200 per cent) in comparison with the cylindrical case. Research limitations/implications The study of bubble collapse is a key point to understand the physical mechanism involved in cavitation erosion. The bubble collapse close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet that penetrates through the bubble and the generation of a blast wave during the induced collapse. Both the jet and the blast wave are possible damaging mechanisms. However, the high-speed dynamics, the small spatio-temporal scales and the complicated physics involved in these processes make any theoretical and experimental approach a challenge. Practical implications Cavitation erosion is a major problem for hydraulic and marine applications. It is a limiting point for the conception and design of such components. Originality/value Such a comparison of multiphase models in the case of a strong shock-induced bubble collapse is clearly original. Usually models are tested separately leading to a large dispersion of results. Moreover, simulations of a three-dimensional bubble collapse are scarce in the literature using such ﬁne grids.

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Piscicchia, Kristian, Massimiliano Bazzi, Mario Bragadireanu, Michael Cargnelli, Alberto Clozza, Luca De Paolis, Raffaele Del Grande, et al. "γ-ray high sensitivity tests of Collapse Models." Journal of Physics: Conference Series 2156, no. 1 (December 1, 2021): 012167. http://dx.doi.org/10.1088/1742-6596/2156/1/012167.

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Abstract The article reviews our recent experimental results on the Continuous Spontaneous Localization (CSL) model and on the gravity related collapse model developed by Diósi and Penrose (DP). These models of dynamical reduction of the wave function consist in non-linear and stochastic modifications of the Schröedinger equation, which lead to a progressive breakdown of the superposition principle, as the size of the system increases. We performed a high sensitivity survey of the spontaneous radiation phenomenon, predicted by the collapse models, at the Gran Sasso underground National Laboratory of INFN in Italy. Our studies set the strongest bounds on the CSL parameters, in a broad region of the parameters space, and rule out the DP in its present formulation.

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Kanari-Naish, Lydia A., Jack Clarke, Michael R. Vanner, and Edward A. Laird. "Can the displacemon device test objective collapse models?" AVS Quantum Science 3, no. 4 (December 2021): 045603. http://dx.doi.org/10.1116/5.0073626.

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Benetti, Micol, Susana J. Landau, and Jailson S. Alcaniz. "Constraining quantum collapse inflationary models with CMB data." Journal of Cosmology and Astroparticle Physics 2016, no. 12 (December 19, 2016): 035. http://dx.doi.org/10.1088/1475-7516/2016/12/035.

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Bassi, Angelo, and Hendrik Ulbricht. "Collapse models: from theoretical foundations to experimental verifications." Journal of Physics: Conference Series 504 (April 14, 2014): 012023. http://dx.doi.org/10.1088/1742-6596/504/1/012023.

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