Collapse Model Research Articles

Minimum measurement time: lower bound on the frequency cutoff for collapse models

The CSL model predicts a progressive breakdown of the quantum superposition principle, with a noise randomly driving the state of the system towards a localized one, thus accounting for the emergence of a classical world within a quantum framework. In the original model the noise is supposed to be white, but since white noises do not exist in nature, it becomes relevant to identify some of its spectral properties. Experimental data set an upper bound on its frequencies, while in this paper we bound it from below. We do so in two ways: by considering a ‘minimal’ measurement setup, requiring that the collapse is completed within the measurement time; and in a measurement modeling-independent way, by requiring that the fluctuations average to zero before the measurement time.

The use of the three-dimensional printed segmented collapsible model of the pelvicalyceal system to improve residents' learning curve.

The aim of the present study was to determine the effectiveness of the use of the three-dimensional (3D) printed segmented collapsible model of the pelvicalyceal system (PCS) to improve the learning curve of the residents. 3D printed models based on computed tomography (CT) images of 10 patients with a staghorn stone were developed. Used images of patients were obtained from CT scans in Digital Imaging and Communications in Medicine format. The area of interest was extracted and saved in stereolithography format. Further, the bioengineer performed virtual segmentation corresponding to the level of each calyces group that was defined by an experienced urologist. The final stage was the printing of each separated detail. Special questionnaire for evaluating the effectiveness of 3D models during both the examination of PCS anatomy and planning percutaneous nephrolithotomy was invented. The determination of the anterior and posterior calyces of the upper group was improved by 61% and 69%, the difference in the determination of the calyces of the middle group was 60% and 51%, and the answers regarding the number of the anterior and posterior calyces of the lower group became better by 67% and 74%, respectively (p<0.001). The ability to select the optimal calyx for the primary and the second access became better by 60% and 55%, respectively (p<0.001). 3D printed segmented collapsible model of the PCS is promising for the improvement of the learning curve of residents and enables to optimize their clinical education, as well as compensate for their lack of experience.

Experimental study on sinkhole collapse monitoring based on distributed Brillouin optical fiber sensor

Sinkhole collapse is a unique geological disaster of the cover soil in karst area, which is very harmful to the safety operation of train and pipeline. In this paper, the distributed Brillouin optical fiber sensing technology was proposed to monitor sinkhole collapse. The Brillouin scattering sensing principle and the strain-displacement relation model were studied firstly. And then, sinkhole collapse model was constructed to validate the feasibility of the monitoring method. Under the static load and coupling loads, the man-made sinkholes collapsed gradually, the distributed optical fiber sensor measure the corresponding strain. Test results show that the distributed optical fiber sensors can effectively monitor the collapse strain even if the ambient temperature changes and the corresponding collapse displacement can be calculated with a good accuracy based on the proposed strain-displacement model.

Edge collapse and subsequent longitudinal accretion in filament S242

Filament S242 is 25 pc long with massive clumps and YSO clusters concentrated in its end regions; it is considered a good example of edge collapse. We mapped this filament in the 12CO(1–0) and 13CO(1–0) lines. A large-scale velocity gradient along filament S242 has been detected; the relative velocity between the two end-clumps is ~3 km s−1, indicating an approaching motion between them. These signatures are consistent with the filament S242 being formed through the collapse of a single elongated entity, where an effect known as “gravitational focusing” drives the ends of the filament to collapse (edge collapse). Based on this picture, we estimate a collapse timescale of ~4.2 Myr, which is the time needed for a finite and elongated entity evolving to the observed filament S242. For the whole filament, we find that increases in surface densities lead to increases in velocity dispersion, which can be consistently explained as the result of self-gravity. We also calculated the contribution of longitudinal collapse to the observed velocity dispersion and found it to be the dominant effect in driving the gas motion near the end-clumps. We propose that our filament S242 is formed through a two-stage collapse model, where the edge collapse of a truncated filament is followed by a stage of longitudinal accretion toward the dense end-clumps.

Jurassic tectonics of the eastern North China Craton: Response to initial subduction of the Paleo-Pacific Plate

AbstractThe Yanshan fold-and-thrust belt (YFTB) on the northern margin of the eastern North China Craton (NCC) contains a succession of Jurassic volcano-sedimentary rocks that record the response of the NCC to the initial stages of subduction of the Paleo-Pacific Plate. We present stratigraphic profiles and new zircon U-Pb data from four basins in the YFTB to constrain the ages of the Jurassic lithological units and tectonic events related to the initial subduction. Following uplift at 200–190 Ma, protracted eruption of basalt at 188–167 Ma reflects the earliest tectonic activity in the YFTB. The eruption occurred in a backarc extensional setting, and migrated toward the west, consistent with WNW-directed subduction of the Paleo-Pacific Plate. The measured profiles and geochronological data demonstrate that the earliest phase of shortening in the YFTB during the Jurassic (event A of the Yanshan Movement in the Chinese literature) took place at 167 Ma. This compression terminated the magmatism and extension of the Early–Middle Jurassic, and resulted in the development of local thrusts, regional uplift, and a disconformity, without involvement of intense folding or the development of an angular unconformity. These observations are consistent with a weak to moderate intensity of deformation. The Jurassic rocks in the YFTB record the response of a backarc to the initial stages of subduction of the Paleo-Pacific Plate. Jurassic tectonics in the YFTB and the entire eastern China continent suggests that initial subduction of the Paleo-Pacific Plate began at ca. 190 Ma, and is consistent with the passive margin collapse model.

Microwave Pyrolysis of Macadamia Shells for Efficiently Recycling Lithium from Spent Lithium-ion Batteries

To reduce harm to the environment and human health and improve economic benefits, the large number of spent lithium-ion batteries that have been produced in recent years need to be reasonably recycled. The purpose of this article is to study a new method, microwave pyrolysis of the shells of macadamia nuts, for efficient recycling of lithium from spent lithium-ion batteries. XRD, SEM, and TGA analyses were used to observe the phase change during roasting. With the help of microwave heating and biomass pyrolysis, the decomposition temperature of Li(Ni1/3Co1/3Mn1/3)O2 was reduced to 300 °C. Carbonated water-soluble Li2CO3 was formed under the action of biochar. Accordingly, the effects of pyrolysis temperature (Pte), biomass dose (bio%), reduction roasting temperature (Rte) and reduction roasting time (Rti) on the leaching rate of lithium were studied, and the results indicated that 93.4% lithium could be leached under the following optimum conditions: bio% = 24, Pte = 500 °C, Rte = 750 °C, and Rti = 25 min. A lattice collapse model and coupling reaction theory explained the benefit of biomass pyrolysis on the decomposition of Li(Ni1/3Co1/3Mn1/3)O2. Finally, we designed a complete process for recycling the cathode powder of spent lithium-ion batteries. This study can guide industrial production to recover lithium-ion batteries in the future.

Turnaround radius in ΛCDM and dark matter cosmologies with shear and vorticity

We determine the relationship between the turnaround radius, ${R}_{\mathrm{t}}$, and mass, ${M}_{\mathrm{t}}$, in $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, and in dark energy scenarios, using an extended spherical collapse model taking into account the effects of shear and vorticity. We find a more general formula than that usually described in literature, showing a dependence of ${R}_{\mathrm{t}}$ from shear, and vorticity. The ${R}_{\mathrm{t}}\ensuremath{-}{M}_{\mathrm{t}}$ relation differs from that obtained not taking into account shear, and rotation, especially at galactic scales, differing $\ensuremath{\simeq}30%$ from the result given in literature. This has effects on the constraint of the $w$ parameter of the equation of state. We compare the ${R}_{\mathrm{t}}\ensuremath{-}{M}_{\mathrm{t}}$ relationship obtained for the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, and different dark energy models to that obtained in the $f(R)$ modified gravity (MG) scenario. The ${R}_{\mathrm{t}}\ensuremath{-}{M}_{\mathrm{t}}$ relationship in $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, and dark energy scenarios are tantamount to the prediction of the $f(R)$ theories. Then, the ${R}_{\mathrm{t}}\ensuremath{-}{M}_{\mathrm{t}}$ relationship is not a good probe to test gravity theories beyond Einstein's general relativity.

Kondo-Induced Giant Isotropic Negative Thermal Expansion.

Negative thermal expansion is an unusual phenomenon appearing in only a handful of materials, but pursuit and mastery of the phenomenon holds great promise for applications across disciplines and industries. Here we report use of x-ray spectroscopy and diffraction to investigate the 4f-electronic properties in Y-doped SmS and employ the Kondo volume collapse model to interpret the results. Our measurements reveal an unparalleled decrease of the bulk Sm valence by over 20% at low temperatures in the mixed-valent golden phase, which we show is caused by a strong coupling between an emergent Kondo lattice state and a large isotropic volume change. The amplitude and temperature range of the negative thermal expansion appear strongly dependent on the Y concentration and the associated chemical disorder, providing control over the observed effect. This finding opens avenues for the design of Kondo lattice materials with tunable, giant, and isotropic negative thermal expansion.

Spectroscopic Confirmation of a Coma Cluster Progenitor at z ∼ 2.2

Abstract We report the spectroscopic confirmation of a new protocluster in the COSMOS field at z ∼ 2.2, COSMOS Cluster 2.2 (CC2.2), originally identified as an overdensity of narrowband selected Hα emitting candidates. With only two masks of Keck/MOSFIRE near-IR spectroscopy in both H (∼1.47–1.81 μm) and K (∼1.92–2.40 μm) bands (∼1.5 hr each), we confirm 35 unique protocluster members with at least two emission lines detected with S/N &gt; 3. Combined with 12 extra members from the zCOSMOS-deep spectroscopic survey (47 in total), we estimate a mean redshift and a line-of-sight velocity dispersion of z mean = 2.23224 ± 0.00101 and σ los = 645 ± 69 km s−1 for this protocluster, respectively. Assuming virialization and spherical symmetry for the system, we estimate a total mass of M vir ∼ (1–2) ×1014 M ⊙ for the structure. We evaluate a number density enhancement of δ g ∼ 7 for this system and we argue that the structure is likely not fully virialized at z ∼ 2.2. However, in a spherical collapse model, δ g is expected to grow to a linear matter enhancement of ∼1.9 by z = 0, exceeding the collapse threshold of 1.69, and leading to a fully collapsed and virialized Coma-type structure with a total mass of M dyn(z = 0) ∼ 9.2 × 1014 M ⊙ by now. This observationally efficient confirmation suggests that large narrowband emission-line galaxy surveys, when combined with ancillary photometric data, can be used to effectively trace the large-scale structure and protoclusters at a time when they are mostly dominated by star-forming galaxies.

The Scattering Map on Oppenheimer\u2013Snyder Space-Time

In this paper, we analyse the boundedness of solutions phi of the wave equation in the Oppenheimer–Snyder model of gravitational collapse in both the case of a reflective dust cloud and a permeating dust cloud. We then proceed to define the scattering map on this space-time and look at the implications of our boundedness results on this scattering map. Specifically, it is shown that the energy of phi remains uniformly bounded going forwards in time and going backwards in time for both the reflective and the permeating cases. It is then shown that the scattering map is bounded going forwards, but not backwards. Therefore, the scattering map is not surjective onto the space of finite energy on mathcal {I}^+cup mathcal {H}^+. Thus, there does not exist a backwards scattering map from finite energy radiation fields on mathcal {I}^+cup mathcal {H}^+ to finite energy radiation fields on mathcal {I}^-. We will then contrast this with the situation for scattering in pure Schwarzschild.

Collapse prediction of pipe subjected to combined loads

Prediction of tubular performance has over the last decades improved with models that are more accurate. There is a trend in the oil and gas industry where traditional uniaxial modelling is given less importance and the triaxial consideration is gaining ground. The American Petroleum Institute (API) added a formula to the standard to consider the effect of internal pressure on the collapse strength in the early 1980s. In 2015, API issued an addendum to the API Technical Report 5C3 (TR 5C3) where the triaxially based collapse strength method was incorporated. This was a more accurate method of incorporating the effect of internal pressure and axial stress on collapse strength. The validity of the formula was demonstrated by collapse strength tests with simultaneous internal pressure by an API work group – API WG 2370 (Greenip, 2016).In 2007, API/ISO presented an ultimate strength (ULS) method for predicting collapse. The new calculation, referred to as the Klever & Tamano model, was developed by API/ISO Work Group 2b (WG2b) under the Steering Committee 5 (SC5) for tubular goods. Following 2986 collapse tests of quenched and tempered tubular specimens; the Klever & Tamano (K&T) model has since been presented as the most accurate ULS model for collapse prediction.This paper compares the collapse prediction performed by the Klever & Tamano model with the 2015 API model using the triaxial collapse tests performed by Greenip for API. Comparison of the K&T (ULS) model and the traditional API (minimum performance) model requires some considerations to establish common ground before the results can be compared. The K&T model builds on a probabilistic estimation of the pipe properties while key components of the API prediction is empirical. The resulting collapse prediction for the entire batch is 3.11% lower than actual for K&T and 20.9% for API. Using two standard deviations, the collapse prediction of K&T is 14.7% lower than actual. Increasing to three standard deviations, the K&T model coincides with the API triaxial model from 2015 for the investigated pipe. No figures reported include any design factors. These results support that slimmer tubular designs can be made, exercising detailed control of safety margins to collapse. A generic example shows a reduction of $47,000USD per well for a typical 13 000 ft long well in an 8.6 lb/gal (1.03 sg) pressure gradient.

Bouncing compact objects. Part I. Quantum extension of the Oppenheimer-Snyder collapse

This article proposes a generalization of the Oppenheimer-Snyder model which describes a bouncing compact object. The corrections responsible for the bounce are parameterized in a general way so as to remain agnostic about the specific mechanism of singularity resolution at play. It thus develops an effective theory based on a thin shell approach, inferring generic properties of such a UV complete gravitational collapse. The main result comes in the form of a strong constraint applicable to general UV models: if the dynamics of the collapsing star exhibits a bounce, it always occurs below, or at most at the energy threshold of horizon formation, so that only an instantaneous trapping horizon may be formed while a trapped region never forms. This conclusion relies solely on i) the assumption of continuity of the induced metric across the time-like surface of the star and ii) the assumption of a classical Schwarzschild geometry describing the (vacuum) exterior of the star. In particular, it is completely independent of the choice of corrections inside the star which leads to singularity-resolution. The present model provides thus a general framework to discuss bouncing compact objects, for which the interior geometry is modeled either by a classical or a quantum bounce. In the latter case, our no-go result regarding the formation of trapped region suggests that additional structure, such as the formation of an inner horizon, is needed to build consistent models of matter collapse describing black-to-white hole bounces. Indeed, such additional structure is needed to keep quantum gravity effects confined to the high curvature regime, in the deep interior region, providing thus a new challenge for current constructions of quantum black-to-white hole bounce models.

The effect of triaxiality on finite element deletion strategies for simulating collapse of full-scale steel structures

Collapse prediction of steel structures should incorporate a finite element model that accounts for ductile fracture through material separation in critical structural members. Finite element deletion approaches have been used successfully in the past to account for fracture in steel members. However, the current common approach in collapse modeling of steel structures, a constant critical strain strategy (CS), typically requires recalibration when used with different structural configurations due to the fact that it does not account for triaxiality, which is a primary parameter in ductile fracture. To better predict structural response of steel structures undergoing collapse, it is important to study the effect of triaxiality on fracture in steel structures. A new finite element deletion approach that accounts for triaxiality was previously proposed, calibrated, and validated in small steel specimens for use in predicting collapse of steel structures. In this approach, fracture initiation is modeled using Void Growth Model (VGM) and the subsequent softening of the material to element deletion is modeled by a Hillerborg model. This paper describes the change of triaxiality, equivalent plastic strain, and other parameters during the duration of the loading, influencing the strategies implemented and provides explanation for the performance shown. In addition, the paper examines the effect of triaxiality on accurately predicting fracture in steel structures through comparison of VGM to CS strategy with validation in simulations of full-scale structural steel connection and frame tests without recalibration. The VGM strategy provided an accurate prediction based on calibration to test results that are most widely available for different types of structural steels, while CS strategy frequently provided less accurate results. The VGM strategy thus allows for an accurate collapse modeling of steel structures for use by researchers, code developers, and practitioners who address collapse of steel structures.

A model-based approach to the tempo of “collapse”: The case of Rapa Nui (Easter Island)

Rapa Nui (Easter Island, Chile) presents a quintessential case where the tempo of investment in monumentality is central to debates regarding societal collapse, with the common narrative positing that statue platform (ahu) construction ceased sometime around AD 1600 following an ecological, cultural, and demographic catastrophe. This narrative remains especially popular in fields outside archaeology that treat collapse as historical fact and use Rapa Nui as a model for collapse more generally. Resolving the tempo of “collapse” events, however, is often fraught with ambiguity given a lack of formal modeling, uncritical use of radiocarbon estimates, and inattention to information embedded in stratigraphic features. Here, we use a Bayesian model-based approach to examine the tempo of events associated with arguments about collapse on Rapa Nui. We integrate radiocarbon dates, relative architectural stratigraphy, and ethnohistoric accounts to quantify the onset, rate, and end of monument construction as a means of testing the collapse hypothesis. We demonstrate that ahu construction began soon after colonization and increased rapidly, sometime between the early-14th and mid-15th centuries AD, with a steady rate of construction events that continued beyond European contact in 1722. Our results demonstrate a lack of evidence for a pre-contact ‘collapse’ and instead offer strong support for a new emerging model of resilient communities that continued their long-term traditions despite the impacts of European arrival. Methodologically, our model-based approach to testing hypotheses regarding the chronology of collapse can be extended to other case studies around the world where similar debates remain difficult to resolve.

A model of quantum collapse induced by gravity

We discuss a model where a spontaneous quantum collapse is induced by the gravitational interaction, treated classically. Its dynamics couples the standard wave function of a system with the Bohmian positions of its particles, which are considered as the only source of the gravitational attraction. The collapse is obtained by adding a small imaginary component to the gravitational coupling. It predicts extremely small perturbations of microscopic systems, but very fast collapse of QSMDS (quantum superpositions of macroscopically distinct quantum states) of a solid object, varying as the fifth power of its size. The model does not require adding any dimensional constant to those of standard physics.

Room temperature test of the continuous spontaneous localization model using a levitated micro-oscillator

The Continuous Spontaneous Localization (CSL) model predicts a tiny break of energy conservation via a weak stochastic force acting on physical systems, which triggers the collapse of the wave function. Mechanical oscillators are a natural way to test such a force; in particular levitated micro-mechanical oscillator has been recently proposed to be an ideal system. We report a proof-of-principle experiment with a micro-oscillator generated by a micro-sphere diamagnetically levitated in a magneto-gravitational trap under high vacuum. Due to the ultra-low mechanical dissipation, the oscillator provides a new upper bound on the CSL collapse rate, which gives an improvement of two orders of magnitude over the previous bounds in the same frequency range, and partially reaches the enhanced collapse rate suggested by Adler. Although being performed at room temperature, our experiment has already exhibits advantages over those operating at low temperatures previously reported. Our results experimentally show the potential of magneto-gravitational levitated mechanical oscillator as a promising method for testing collapse model. Further improvements in cryogenic experiments are discussed.

In Praise and in Criticism of the Model of Continuous Spontaneous Localization of the Wave-Function

Different attempts to solve the measurement problem of the quantum me-chanics (QM) by denying the collapse principle, and replacing it with changes in the quantum formalism, failed because the changes in the formalism lead to contradictions with QM predictions. To the difference, Ghirardi, Rimini and Weber took the collapse as a real phenomenon, and proposed a calculus by which the wave-function should undergo a sudden localization. Later on, Ghirardi, Pearle and Rimini came with a change of this calculus into the CSL (continuous spontaneous localization) model of collapse. Both these proposals rely on the experimental fact that the reduction of the wave-function occurs when the microscopic system encounters a macroscopic object and involves a big amount of its particles. Both these proposals also change the quantum formalism by introducing in the Schr?dinger equation additional terms with noisy behavior. However, these terms have practically no influence as long as the studied system contains only one or a few components. Only when the amount of components is very big, these terms become significant and lead to the reduction of the wave-function to one of its components. The present work has two purposes: 1) proving that the collapse postulate is unavoidable; 2) ap-plying the CSL model to the process in a detector and showing step by step the modification of the wave-function, until reduction. As a side detail, it is argued here that the noise cannot originate in some classical field, contrary to the thought/hope of some physicists, because no classical field is tailored by the wave-functions of entanglements.

VIP2 at Gran Sasso - Test of the validity of the spin statistics theorem for electrons with X-ray spectroscopy

In the VIP2 VIolation of the Pauli Exlusion Principle (PEP) experiment at the Gran Sasso underground laboratory (LNGS) we are searching for possible violations of standard quantum mechanics predictions. With high precision we investigate the Pauli Exclusion Principle and the collapse of the wave function (collapse models). We will present our experimental method of searching for possible small violations of the Pauli Exclusion Principle for electrons, via the search for “anomalous” X-ray transitions in copper atoms, produced by “new” electrons (brought inside a copper bar by circulating current) which could have the probability to undergo Pauli-forbidden transition to the ground state (1 s level) already occupied by two electrons. We will describe the concept of the VIP2 experiment taking data at LNGS presently. The goal of VIP2 is to test the PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10−31. We will show preliminary experimental results obtained at LNGS and discuss implications of a possible violation.

The Jet formation in Ring-shape Laser Induced forward transfer

In this study, ring-shape laser spot was used to induce a ring-shape cavitation aiming to improve the separation accuracy in the laser induced forward transfer (LIFT) process. The roles of laser pulse energy and the size of the ring-shape laser spot on jet formation in LIFT process were theoretically analyzed with ring-shape bubble collapse model established by Lattice Boltzmann Method. The results show that the geometrical symmetry of the ring-shape cavitation blocks the interaction between the inner and outer liquids, leading to higher separation accuracy. The simulation results show that under a specific ratio of internal and external diameter of the ring-shape laser spot, a secondary produced vortex velocity flow can further promote the accuracy of the transferring.

Effect of Porosity on Dynamic Mechanical Properties and Impact Response Characteristics of High Aluminum Content PTFE/Al Energetic Materials.

In order to obtain the effect of porosity on the dynamic mechanical properties and impact response characteristics of high aluminum content PTFE/Al energetic materials, PTFE/Al specimens with porosities of 1.2%, 10%, 20%, and 30% were prepared by adding additives. The dynamic compression properties and impact response characteristics of high aluminum content PTFE/Al energetic materials with porosity were studied by using a split Hopkinson pressure bar (SHPB) impact loading experimental system. Based on the one-dimensional viscoplastic hole collapse model, an impact temperature rise analysis model including melting effects was used, and corresponding calculation analysis was performed. The results show that with the increase of porosity, the yield strength and compressive strength of the material will decrease. Under dynamic loading, the reaction duration of PTFE/Al energetic materials with different porosities generally shows a tendency to become shorter as the porosity increases, while the ignition delay time is basically unchanged. In this experiment, the material response has the optimal porosity with the lowest critical strain rate, the optimal porosity for PTFE/Al energetic materials with different porosity and high aluminum content (50/50 mass ratio, size of specimens Φ8 × 5 mm) is 10%. The research results can provide an important reference for the engineering application of PTFE/Al energetic materials.