Sudden Release Of Energy Research Articles

A dynamic magnetic tension force as the cause of failed solar eruptions.

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has not yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. Here we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. This magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.

A search for Galactic transients disguised as gamma-ray bursts

A significant fraction of cosmological gamma-ray bursts (GRBs) are characterised by a fast rise and exponential decay (FRED) temporal structure. This is not a distinctive feature of this class, since it is observed in many Galactic transients and is likely descriptive of a sudden release of energy followed by a diffusion process. Possible evidence has recently been reported by Tello et al. (2012) for a Galactic contamination in the sample of FRED GRBs discovered with Swift. We searched for possible Galactic intruders disguised as FRED GRBs in the Swift catalogue up to September 2014. We selected 181 FRED GRBs (2/3 with unknown redshift) and considered different subsamples. We tested the degree of isotropy through the dipole and the quadrupole moment distributions, both with reference to the Galaxy and in a coordinate-system-independent way, as well as with the two-point angular autocovariance function. In addition, we searched for possible indicators of a Galactic origin among the spectral and temporal properties of individual GRBs. We found marginal (~3 sigma) evidence for an excess of FREDs with unknown redshift towards the Galactic plane compared with what is expected for an isotropic distribution corrected for the non-uniform sky exposure. However, when we account for the observational bias against optical follow-up observations of low-Galactic latitude GRBs, the evidence for anisotropy decreases to ~2 sigma. In addition, we found no statistical evidence for different spectral or temporal properties from the bulk of cosmological GRBs. We found marginal evidence for the presence of a disguised Galactic population among Swift GRBs with unknown redshift. The estimated fraction is f=(19 +- 11)%, with an upper limit of 34% (90% confidence).

FractalAnalyzer: A MATLAB Application for Multifractal Seismicity Analysis

Earthquakes are seismic phenomena caused by the sudden release of energy in the Earth’s crust. Their effects range from ground shaking to faulting. Geological and geophysical studies, especially in light of plate tectonic theory have been used to explain the occurrence of earthquakes. Thus from the point of view of statistical fractals, earthquakes cannot be interpreted as random independent events (i.e., having Poisson distribution). Rather, it is observed that the events of the same sequence are clustered in time and space (Shlien and Toksoz, 1970; Vere?Jones, 1970; Smalley et al., 1987; De Natale et al., 1988; Roy and Mondal, 2012a,b).

PREDICTION OF EARTHQUAKES AND REDUCING DAMAGES

An earthquake also known as tremor or temblor is the result of a sudden release of energy in the Earth’s crust that creates seismic waves. An earthquake may cause injury and loss of life, roads and bridge damage, general property damage, and collapse or destabilization of buildings. The objective of earthquake engineering is to foresee the impact of earthquakes on buildings and other structures and to design such structures to minimize the risk of damage. Existing structures can be modified by seismic retrofitting to improve their resistance to earthquakes. Methodologies to anticipate earthquakes require to be developed, so that early warning can be issued to avoid heavy casualties and major damages.

On the borderline between Science and Philosophy: A debate on determinism in France around 1880

In the second half of the nineteenth century, a new interest in explosive chemical reactions, sudden release of energy in living beings, physical instabilities, and bifurcations in the solutions of differential equations drew the attention of some scholars. New concepts like triggering actions and guiding principles also emerged. Mathematicians, physicists, physiologists, and philosophers were attracted by this kind of phenomena since they raised a question about the actual existence of a strict determinism in science. In 1878 the mathematical physicist Joseph Boussinesq pointed out a structural analogy among physical instabilities, some essential features of living beings, and singular solutions of differential equations. These developments revived long-lasting philosophical debates on the problematic link between deterministic physical laws and free will. We find in Boussinesq an original and almost isolated attempt to merge mathematical, physical, biological, and philosophical issues into a complex intellectual framework. In the last decades, some philosophers of science rediscovered the connection between physical instabilities and determinism, both in the context of chaos theory, and in the debates on the Norton dome. I put forward a consistent historical reconstruction of the main issues and characters involved.

Experimental observation and numerical simulation of SiC3D/Al interpenetrating phase composite material subjected to a three-point bending load

The failure process and the underlying mechanism of crack initiation, crack propagation and eventual fracture of SiC3D/Al interpenetrating phase composite subjected to a static three-point bending load were investigated using in-situ SEM observation and two-dimensional microstructure-embedded numerical simulation. It was found that stress concentration originally occurred in the SiC ceramic phase near the bottom of the specimen, causing horizontal tensile forces and inducing a vertical microcrack inside the SiC phase near the SiC–Al interface. With increased load, more microcracks were gradually initiated in the SiC phase, and severe tearing plastic deformation and cracking of the Al phase occurred at the base of the specimen. Subsequently, the microcracks propagated and connected to form a primary crack. It was notable that at the final stage of the primary crack, cracking in the Al phase no longer occurred due to the sudden release of the internal energy in the composite material. Interestingly, the primary crack bridged over the Al phase then continued to propagate in the SiC material. Simulated results were consistent with observed behavior.

CRITICAL COMPARISON OF GROUND MOTION ATTENUATION FORMULAE FOR RECENT EARTHQUAKE DATA

Earthquake refers to the sudden release of energy in the earth’s crust that creates seismic waves. Earthquakes are unpredictable and their intensity attenuates over long distances. In an idealized situation earth is considered to be elastic and the seismic waves can propagate indefinitely once they are excited. But it is known that the real earth is not perfectly elastic. This causes the waves that are propagating to attenuate with time as they travel. Uncertainties persist in the attenuation equations as they depend on many factors such as epicentral distance, focal depth, geology, fault characteristics, magnitude, topography etc. Many attenuation equations have been developed over the years considering various factors. The present work focuses on validating and critically comparing popular attenuation equations such as Sarma (2000), Smit (2000), Tento(1992), Jacob(1990) etc. for earthquake data of recent times (2005 onwards). An attempt is made to collect as much information as possible from different stations during different earthquakes. The accuracy and effectiveness of different attenuation equations are verified. Also attempt is made to study the sensitiveness of different factors influencing the seismicity. Further it has been inferred that each formula has its own merits and demerits and an attempt is made to identify the most effective attenuation formula for wide range of earthquake data.

Propagation of Magnetohydrodynamic Shock Waves

The propagation of magnetohydrodynamic shock waves in a self gravitating gas sphere has been studied. The shock is supposed to be generated as a result of sudden release of energy at the centre of symmetry. A similarity solution for the flow is developed. Numerical results for three different values of mach-number given by M/sup2/=200, 100 and 10 are obtained. The magnetic field affects the boundary conditions at the shock as well as the flow behind it. For a fixed increase M, the particle velocity, density and gas pressure decreases as the initial magnetic field increase. In the flow field behind the shock, there exists a transition region across which the effect of magnetic field is reversed.

THE EVOLUTION OF HIGH-TEMPERATURE PLASMA IN MAGNETAR MAGNETOSPHERES AND ITS IMPLICATIONS FOR GIANT FLARES

In this paper we propose a new mechanism describing the initial spike of giant flares in the framework of the starquake model. We investigate the evolution of a plasma on a closed magnetic flux tube in the magnetosphere of a magnetar in the case of a sudden energy release and discuss the relationship with observations of giant flares. We perform one-dimensional numerical simulations of the relativistic magnetohydrodynamics in Schwarzschild geometry. We assume energy is injected at the footpoints of the loop by a hot star surface containing random perturbations of the transverse velocity. Alfv\'en waves are generated and propagate upward, accompanying very hot plasma that is also continuously heated by nonlinearly generated compressive waves. We find that the front edges of the fireball regions collide at the top of the tube with their symmetrically launched counterparts. This collision results in an energy release which can describe the light curve of initial spikes of giant flares.

A Procedure to Determine the Optimal Sensor Positions for Locating AE Sources in Rock Samples

Within a research work aimed to better understand frost weathering mechanisms of rocks, laboratory tests have been designed to specifically assess a theoretical model of crack propagation due to ice segregation process in water-saturated and thermally microcracked cubic samples of Arolla gneiss. As the formation and growth of microcracks during freezing tests on rock material is accompanied by a sudden release of stored elastic energy, the propagation of elastic waves can be detected, at the laboratory scale, by acoustic emission (AE) sensors. The AE receiver array geometry is a sensitive factor influencing source location errors, for it can greatly amplify the effect of small measurement errors. Despite the large literature on the AE source location, little attention, to our knowledge, has been paid to the description of the experimental design phase. As a consequence, the criteria for sensor positioning are often not declared and not related to location accuracy. In the present paper, a tool for the identification of the optimal sensor position on a cubic shape rock specimen is presented. The optimal receiver configuration is chosen by studying the condition numbers of each of the kernel matrices, used for inverting the arrival time and finding the source location, and obtained for properly selected combinations between sensors and sources positions.

Evolution of red Nova V4332 Sagittarii remnant

We present the multicolor BV RI photometry and BTA/SCORPIO spectroscopy for the red nova V4332 Sgr, performed in 2005–2012. We have analyzed the behavior of the nova remnant, considering our observations along with all the published observations and archival photographic photometry. The atomic and molecular emission spectra show an exponential weakening. Since 2003, the line fluxes have on the average decreased 30-fold. The continuum of the M-type giant in the spectrum has weakened abruptly between 2006 and 2008, twice in the red and by 4 times in the blue range. The variations in the spectral energy distribution of the stellar continuum after the outburst correspond to a decrease in the surface temperature of the M-type giant by 1000 K. The presence of a faint star of about 20m is possible. The star can be either a member of the system or a field star. It is found that the phenomenon of the red nova in this system is not related with the M-type star. The progenitor of the explosion could be a blue straggler, which has disappeared from the spectral energy distribution after the explosion of 1994. It is most likely that this object was a contact binary system. To explain the “cold explosion” of V4332 Sgr, we have accepted the hypothesis of merging components of a contact binary star in a hierarchical triple or multiple system. There are evidences of dynamical destruction of the outburst remnant and accretion of its matter to the M-type giant. The cause of the red nova phenomenon is thought to be a sudden explosive energy release in the center of a star having a massive envelope, and a subsequent expansion of the envelope in the conditions close to adiabatic. As a result of the explosion, thermal energy reaches the surface of the envelope a year or a few years after the outburst, whereas the envelope already has a large surface area. The cause of the explosion in the center of the star can be both a merger event of the nuclei of two stars in the contact system with a formed common massive envelope and instability in the core of a single massive star. Thus, the red novae can be heterogeneous objects at different evolutionary stages.

Study on the Correlation of Shallow Source Earthquake and Mine Dynamic Disasters in the Weast of Beijing

Mine dynamic disasters is due to a sudden release of energy by mine engineering disturbed. Shallow-focus earthquake is due to plate movement caused by sudden release of energy. In this paper, on the basis of plate tectonics, geophysical, In this paper, on the basis of plate tectonics, geophysical, through the shallow source analogy is the mechanism of dynamic disaster, earthquake and mine exploration seismic energy result in mine power. The mechanism of disaster analysis seismic energy has the possibility of mine dynamic disaster, combining shallow-focus earthquake and the mine dynamic natural disaster site scheduling, and shallow-focus earthquake and the mine dynamic disasters of space position relations. Analysis in complex geological conditions shallow-focus earthquake geological structure as the first energy transmission medium for mine power disaster role relationship, for the prediction of mine dynamic disaster and the effective prevention and control provides the basis of the production test.

Inhomogeneous Micro-Structure Influence on Macro-Crack of Sandstone

Abstract SEM scanning and fractal dimension estimation were adopted to study the inhomogeneous microstructure features and its influences on the failure pattern of sandstone. The results show that different sandstones are of different self-similarities of microstructure. The average homogeneities of lithic arenite, greywacke, and subfeldspathic arenite are 5.61, 3.39, and 4.57 and estimated fractal dimensions of microstructure are 1.94, 1.52, and 1.84, respectively, indicating that the homogeneity of microstructure is well consistent with fractal dimension. The resulted macro-cracks of lithic arenite, greywacke, and subfeldspathic arenite are vertical cleavages, unordered discontinuous macro-cracks, and inclined macro-crack, respectively. The brittleness of lithic arenite, greywacke, and subfeldspathic arenite are 2.46, 3.54, and 2.61, respectively. The sandstone of brittleness tends to be easily ruptured in an abrupt manner, accompanying a sudden release of large elastic energy.

Forward to special issue on blast and impact of engineering structures

The blast and impact behaviour of structures are dependent on many factors, such as the type of loading and the behaviour of constituent materials at high strain rates. Blast can be defined as a large scale, rapid and sudden release of energy. For example, in physical explosions, energy may be released from the catastrophic failure of a pressure vessel, or from the chemical interaction of two or more liquids. Structural impact deals with the behaviour of structures and components subjected to large dynamic loads involving contact, which could be the outcome, for example, of a high velocity projectile or a high speed crash. The prediction of the effect of a blast load on a structure is an important step in designing advanced blast protective structures. Blast energy is released within a very short period of time, which can be less than 1ms, making it challenging for protection material to absorb a majority of the blast energy. For blast impact analysis, the complexity of the problem can be attributed to the high speed wave front propagation, the flow of materials under these conditions, and the large structural deformation. Researchers are actively pursuing all these issues related to blast and impact analysis and means of developing protection against blast and impact forces. Since an explosion is a hypervelocity impact, numerical simulation is an attractive method to

MAGNETAR GIANT FLARES—FLUX ROPE ERUPTIONS IN MULTIPOLAR MAGNETOSPHERIC MAGNETIC FIELDS

We address a primary question regarding the physical mechanism that triggers the energy release and initiates the onset of eruptions in the magnetar magnetosphere. A self-consistent stationary, axisymmetric model of the magnetar magnetosphere is constructed based on a force-free magnetic field configuration which contains a helically twisted force-free flux rope. Given the complex multipolar magnetic fields at the magnetar surface, we also develop a convenient numerical scheme to solve the GS equation. Depending on the surface magnetic field polarity, there exist two kinds of magnetic field configurations, inverse and normal. For these two kinds of configurations, variations of the flux rope equilibrium height in response to gradual surface physical processes, such as flux injections and crust motions, are carefully examined. We find that equilibrium curves contain two branches, one represents a stable equilibrium branch, the other an unstable equilibrium branch. As a result, the evolution of the system shows a catastrophic behavior: when the magnetar surface magnetic field evolves slowly, the height of flux rope would gradually reach a critical value beyond which stable equilibriums can no longer be maintained. Subsequently the flux rope would lose equilibrium and the gradual quasi-static evolution of the magnetar magnetosphere will be replaced by a fast dynamical evolution. In addition to flux injections, the relative motion of active regions would give rise to the catastrophic behavior and lead to magnetic eruptions as well. We propose that a gradual process could lead to a sudden release of magnetosphere energy on a very short dynamical timescale, without being initiated by a sudden fracture in the crust of the magnetar. Some implications of our model are also discussed.

Evaluation of rockburst potential in a cut-and-fill mine using energy balance

Rockburst has been one of major hazards in underground mines, including cut-and-fill mines and it must be properly prevented. The rockburst is characterized by a sudden release of strain energy in the highly stressed pillar that often causes local violent failure of the pillar. An evaluation of rockburst potential based on the ration between stored strain energy and released strain energy has been carried out. It included laboratory work where the specimens were tested in loading-unloading uniaxial compression and numerical analysis of a cut-and-fill mine. The laboratory experiments revealed that the quartz vein samples have very low to high rockburst potential whereas the numerical analysis showed that the crown pillar of quartz vein would have low to moderate rockburst potential.

Fire-ball expansion and subsequent shock wave propagation from explosives detonation

A well-known problem in thermo-hydrodynamics involves the sudden release of the explosion energy, concentrated in a finite volume, to surroundings with uniform density. However, only similarity solutions which have no detailed information on the earlier behavior of the fire-ball are available on this problem. In this study, we obtain a set of analytical solutions for the time dependent radius of an expanding fire-ball after explosives detonation by solving continuity, Euler and energy equations using a “polytrope” assumption for the fire-ball center. Subsequent spherical shock waves that develop from the fire-ball are obtained using the Kirkwood–Bethe hypothesis with Tait's equation of state for water and the ideal gas equation of state for air. The pressure waves emanating from the oscillating bubble in underwater, which has a notably different time scale from the shock wave generation, are obtained using the Rayleigh equation. The calculated results for the period and the maximum radius of bubble that resulted from the fire-ball and the pressure wave from the oscillating bubble in underwater are similar to the observed ones (Swift and Decius, 1946: Yennie and Arons, 1946). The calculated peak pressures as a function of shock radius in air medium were comparable to those observed (Swisdak, 1975).

Optimization of Composite Structures to Delay Mode Jump Instabilities

DOI: 10.2514/1.J050590 Numerous studies have shown that postbuckling stiffened panels may undergo abrupt changes in buckled mode shape when loaded in uniaxial compression. This phenomenon is often referred to as a mode jump or secondary instability. The resulting sudden release of stored energy may initiate damage in vulnerable regions within a structure, for example, at the skin-stiffener interface of a stiffened composite panel. Current design practice is to removeamodejumpbyincreasingtheskinthicknessofthepostbucklingregion.Alayupoptimizationmethodology, based on a genetic algorithm, is presented, which delays the onset of secondary instabilities in a composite structure while maintaining a constant weight and subject to a number of design constraints. A finite element model was developed of a stiffened panel’s skin bay, which exhibited secondary instabilities. An automated numerical routine extracted information directly from the finite element displacement results to detect the onset of initial buckling and secondaryinstabilities.Thisroutinewaslinkedtothegeneticalgorithmto findarevisedlayupfortheskinbay,within appropriate design constraints, to delay the onset of secondary instabilities. The layup optimization methodology, resulted in a panel that had a higher buckling load, prebuckling stiffness, and secondary instability load than the baseline design.

Superflares on solar-type stars

Solar flares are caused by the sudden release of magnetic energy stored near sunspots. They release 10(29) to 10(32) ergs of energy on a timescale of hours. Similar flares have been observed on many stars, with larger 'superflares' seen on a variety of stars, some of which are rapidly rotating and some of which are of ordinary solar type. The small number of superflares observed on solar-type stars has hitherto precluded a detailed study of them. Here we report observations of 365 superflares, including some from slowly rotating solar-type stars, from about 83,000 stars observed over 120 days. Quasi-periodic brightness modulations observed in the solar-type stars suggest that they have much larger starspots than does the Sun. The maximum energy of the flare is not correlated with the stellar rotation period, but the data suggest that superflares occur more frequently on rapidly rotating stars. It has been proposed that hot Jupiters may be important in the generation of superflares on solar-type stars, but none have been discovered around the stars that we have studied, indicating that hot Jupiters associated with superflares are rare.

Solar wind energy input during prolonged, intense northward interplanetary magnetic fields: A new coupling function

[1] Sudden energy release (ER) events in the midnight sector auroral zone during intense (B > 10 nT), long-duration (T > 3 h), northward (N = Bz > 0 nT) IMF magnetic clouds (MCs) during solar cycle 23 (SC23) have been examined in detail. The MCs with northward-then-southward (NS) IMFs were analyzed separately from MCs with southwardthen-northward (SN) configurations. It is found that there is a lack of ER/substorms during the N field intervals of NS clouds. In sharp contrast, ER events do occur during the N field portions of SN MCs. From the above two results it is reasonable to conclude that the latter ER events represent residual energy remaining from the preceding S portions of the SN MCs. We derive a new solar wind–magnetosphere coupling function during northward IMFs: ENIMF = a N −1/12 V 7/3 B 1/2 + b V |Dstmin|. The first term on the right-hand side of the equation represents the energy input via “viscous interaction,” and the second term indicates the residual energy stored in the magnetotail. It is empirically found that the magnetotail/magnetosphere/ionosphere can store energy for a maximum of ∼4 h before it has dissipated away. This concept is defining one for ER/substorm energy storage. Our scenario indicates that the rate of solar wind energy injection into the magnetotail/ magnetosphere/ionosphere for storage determines the potential form of energy release into the magnetosphere/ionosphere. This may be more important to understand solar wind–magnetosphere coupling than the dissipation mechanism itself (in understanding the form of the release). The concept of short-term energy storage is also applied for the solar case. It is argued that it may be necessary to identify the rate of energy input into solar magnetic loop systems to be able to predict the occurrence of solar flares.