Phenomenon Of Bursts Research Articles

Surging Phenomenon in Gas Engine Crankcase

An internal combustion engine is an engine whose combustion process is inside a closed room or often referred to as the combustion chamber. The Wartsila W20V34SG engine is one of the internal combustion engines used to turn generators to generate electricity, over time some new problems arise that cause engine trip. One cause of a sudden increase in crankcase pressure is the occurrence of the phenomenon of surging in the crankcase. The causes of surging originating from the phenomenon of bursts of engine exhaust gas leaks to the surface of the oil mist pipe. Where the average temperature of the exhaust gas is approximately 530 °C so that the hot gas burst increases the temperature of the oil mist pipe and result in lower gas density and oil vapor. This phenomenon causes the air to become lighter and rise to the top and make the room in the crankcase more vacuum up to -6.29 mBar at which point the pressure will rise significantly up to ± 25 mBar. This value has exceeded the limit of the crankcase pressure protection setting which is 5.57 mBar causing the engine to trip.

Pulse-duration dependent sequential double ionization by elliptically polarized laser pulses

Using a fully classical model, we have studied sequential double ionization of argon driven by elliptically polarized laser pulses at intensities well in the over-barrier ionization region. The results show that the joint electron momentum distributions in the minor elliptical direction depend strongly on the pulse duration. From pulse number N = 4 to 10, the clustering regions of the joint electron momentum increase with the pulse duration. For even larger pulse durations, the clustering region does not increase further but the population of the joint electron momentum in these regions changes with the pulse duration. Back analysis of double ionization trajectories shows the phenomenon of multiple ionization bursts and the pulse duration-dependent multiple ionization bursts of the second electron is responsible for the evolution of the joint electron momentum distribution with the pulse duration.

Numerical models of cosmological evolution of a degenerate Fermi-system of scalar charged particles

Based on the previously constructed mathematical model of a statistical Fermi system with particle interaction, in this paper we construct and analyze numerical models of cosmological evolution of a single-component degenerate Fermi system of scalar particles. The applied mathematics package Mathematica 9 is used for numerical model construction. It is strictly proved that the conservation law for the total energy of the scalarly charged degenerate Fermi system and a massive scalar field is a differential consequence of the particle number conservation law. Thus the mathematical model of cosmological evolution of the system is reduced to a closed normal set of three essentially nonlinear ordinary differential equations. After transforming the equations to dimensionless variables, an algorithm of its numerical solution is suggested. On the basis of numerical simulation of the cosmological evolution we show the presence of a new phenomenon in the cosmological evolution: it is the phenomenon of phantom bursts of cosmological acceleration at times of the order of 103 Planck times.

Intermittent bursts induced by double tearing mode reconnection

Reversed magnetic shear (RMS) configuration is assumed to be the steady-state operation scenario for the future advanced tokamaks like International Thermonuclear Experimental Reactor. In this work, we numerically discover a phenomenon of violent intermittent bursts induced by self-organized double tearing mode (DTM) reconnection in the RMS configuration during the very long evolution, which may continuously lead to annular sawtooth crashes and thus badly impact the desired steady-state operation of the future advanced RMS tokamaks. The key process of the intermittent bursts in the off-axis region is similar to that of the typical sawtooth relaxation oscillation in the positive magnetic shear configuration. It is interestingly found that in the decay phase of the DTM reconnection, the zonal field significantly counteracts equilibrium field to make the magnetic shear between the two rational surfaces so weak that the residual self-generated vortices of the previous DTM burst are able to trigger a reverse DTM reconnection by curling the field lines.

Variability of GRB light curve: Shock wave model modification

The main topic of our investigation is a mysterious phenomenon of gamma ray bursts. If someone analyses the observation of this events, one can see that the most interesting data are among the gamma phase, during the first couple of seconds. In this stage central engine generate a high intensity and high energy radiation, observed in the form of pulses in the light curve. If we could understood the main physical processes in this phase, we could put some constraints for the model which try to explain the core of this phenomena, deeply hidden from observation by high optical thickness of surrounding material.Observation of the GRB light curve can be easily done with the help of modern satellites, so that the data of this kind are vastly dispersed. We try to analyse them and to explain in details physical process which create the light curve pulses. Our research is based on the broadly accepted scenario of gamma phase in GRBs, which predicts that GRB core generate highly relativistic mater in some amount of time. This mater form shock waves of different velocities, due to highly differential motions. The shock waves can interact with each others, and in that moment radiation significantly increases, creating the observed pulses in the GRB light curve. We develop a phenomenological model based on the model developed by Huang and coauthors, to explain evolution of a shock wave expanding from some distance. In it, we implemented the ability to simulate collision between incoming shock and density barrier. We also propose that the density barrier is created by the material ejected from the core and spread around by the shocks. As a result of simulation we can get synthesized pulses, and by comparing them with the observational data we can acquire values of basic parameters used in our model.

Electromagnetic catastrophe in ultrarelativistic shocks and the prompt emission of gamma-ray bursts

It is shown that an ultrarelativistic shock with the Lorentz factor of order of tens or higher propagating in a moderately dense interstellar medium (density above $\sim 1000 $ cm$^{-3}$) undergoes a fast dramatic transformation into a highly radiative state. The process leading to this phenomenon resembles the first order Fermi acceleration with the difference that the energy is transported across the shock front by photons rather than protons. The reflection of the energy flux crossing the shock front in both directions is due to photon-photon pair production and Compton scattering. Such mechanism initiates a runaway nonlinear pair cascade fed directly by the kinetic energy of the shock. Eventually the cascade feeds back the fluid dynamics, converting the sharp shock front into a smooth velocity gradient and the runaway evolution changes to a quasi-steady state regime. This effect has been studied numerically using the nonlinear Large Particle Monte-Carlo code for the electromagnetic component and a simplified hydrodynamic description of the fluid. The most interesting application of the effect is the phenomenon of gamma-ray bursts where it explains a high radiative efficiencyand gives a perspective to explain spectra of GRBs and their time variability. The results predict a phenomenon of ``GeV bursts'' which arise if the density of the external medium is not sufficiently high to provide a large compactness.

Radio and X-ray signatures of merging neutron stars

We describe the possible electromagnetic signals expected from the magnetospheric interactions of a neutron star binary prior to merger. We find that both radio and X-ray signals of detectable strength are possible. We discuss possible links with the phenomenon of gamma-ray bursts (GRBs) and describe the prospects for direct detection of these signals in searches for radio and X-ray transients.

Marginal Resonances and Intermittent Behaviour in the Motionin the Vicinity of a Separatrix

A condition upon which sporadic bursts (intermittent behaviour) ofthe relative energy become possible is derived for the motion in thechaotic layer around the separatrix of a non-linear resonance. This isa condition for the existence of a marginal resonance, i.e. aresonance located at the border of the layer. A separatrix map inChirikov’s form [Chirikov, B. V., Phys. Reports 52, 263(1979)] is used to describe the motion. In order to provide astraightforward comparison with numeric integrations, the separatrixmap is synchronized to the surface of the section farthest from thesaddle point. The condition of intermittency is applied to clear outthe nature of the phenomenon of bursts of the eccentricity of chaoticasteroidal trajectories in the 3/1 mean motion commensurability withJupiter. On the basis of the condition, a new intermittent regime ofresonant asteroidal motion is predicted and then identified in numericsimulations.

Gamma-Ray Burst Observations with BATSE

Gamma-ray bursts (GRBs) will be recorded as one of the outstanding new phenomena discovered in astronomy this century. About once per day, a burst of gamma rays appears from a random direction on the sky. Often, the burst outshines all other sources of gamma-rays in the sky, combined. This paper reviews some of the key observed phenomenon of bursts in the hard x-ray/gamma-ray region, as observed with the BATSE experiment on the Compton Gamma Ray Observatory. The observed time profiles, spectral properties and durations of gamma-ray bursts cover a wide range. Recent breakthroughs in the observation of gamma-ray burst counterparts and afterglows in other wavelength regions have marked the beginning of a new era in gamma-ray burst research. Those observations are described in following papers in these proceedings.

GAMMA-RAY BURSTS: AN OVERVIEW

ABSTRACT A history and overview of the observed properties of gamma-ray bursts are presented. The phenomenon of gamma-ray bursts is without precedence in astronomy, having no observed property that would be a direct indicator of their distance and no counterpart object in another wavelength region. Their brief, random appearance only in the gamma-ray region has made their study difficult. The observed time profiles, spectral properties and durations of gamma-ray bursts cover a wide range. All proposed models for their origin must be considered speculative. It is humbling to think that even after 25 years since their discovery, the distance scale of gamma-ray bursts is still very much debatable.

Low Energy Lines in Spectra of Gamma Bursts

AbstractWe connect the phenomenon of gamma ray bursts with nuclear explosions on the old neutron stars. The matter of the neutron star in the non-equilibrium layer at depths of 30 m ≤ h ≥ 100 m consists of superheavy (A ≥ 300) nuclei with a surplus of neutrons (A/Z = 3 ÷ 4). These nuclei are metastable and exist only at high pressure. After the starquake some of the matter from non-equilibrium layer may move upwards and its nuclei become unstable. The β-decay is followed by a chain reaction of fission and nuclear explosion. The gamma ray burst is observed as radiation of the star surface heated to high temperature. Some mass may be ejected, forming expanding cloud. It consists mainly of the iron Fe56 with small (≤ 1%) additions of heavy elements (Ba, I, …) arising from the fission. The passage of stellar gamma radiation through the expanding plasma clouds leads to the formation of short-lived spectral features. Strong absorption of the soft gamma rays on K-electrons of Fe56 must be observed in the early stages. The gamma quanta with energies ε = 40–70 keV beyond the K-edge of the heavy elements (Ba, I, …) are absorbed in the later stages. A wide Kα line (εα = 30 keV) appears simultaneously. The free-free emission of expanding hot plasma cloud may be observed as a short flash in optical band.

Phenomenon of rock bursts and resulting shock waves : Litwiniszyn, J Min Sci TechnolV1, N4, Aug 1984, P243–251

Phenomenon of rock bursts and resulting shock waves : Litwiniszyn, J Min Sci TechnolV1, N4, Aug 1984, P243–251

Phenomenon of rock bursts and resulting shock waves : Litwiniszyn, J Min Sci TechnolV1, N4, Aug 1984, P243–251

Phenomenon of rock bursts and resulting shock waves : Litwiniszyn, J Min Sci TechnolV1, N4, Aug 1984, P243–251

Adaptive systems, lack of persistency of excitation and bursting phenomena

The paper considers four algorithms arising in adaptive systems problems, equation error identification, output error identification, reference trajectory following and adaptive pole positioning. Theoretical explanation, backed up by simulations, is offered for the phenomenon of bursts of oscillatory behaviour in the presence of excitations which are not persistently exciting.

The phenomenon of rock bursts and resulting shock waves

A model for the phenomenon of rock bursts has been assumed. Inside a deflected rock beam A located between the seam C and the overlying rock layer B a region of tensile strains is formed above the neutral axis of the beam and a region of compressive strains below that axis. When the resistance limit of the medium is exceeded at the moment t 0, a fissure π is formed. The formation of this fissure initiates longitudinal waves propagating in the regions above and below the neutral axis of the beam. The problem is regarded as unidimensional, assuming the equation of state of the medium in the form σ = σ(ɛ, ∂ɛ/∂t) (σ is stress, ɛ is strain). The strain within the beam above its neutral axis is ɛ > 0 at the instant t = t 0. After the fissure π has been formed during the time t > t 0, it is followed by compression. Within the beam, below its neutral axis, there is ɛ < 0 at the instant t = t 0. During the time t > t 0 expansion takes place. In a particular case of a non-linear dependence σ = σ(ɛ) when d 2σ/dɛ 2 ≠ 0, these phenomena are described by a quasi-linear system of hyperbolic equations. The conditions are given for the generation of a shock wave depending on the form of the equation of state of the medium and the boundary conditions on the surfaces S 1 and S 2 of the fissure π. A programmed execution of these conditions would direct the process of the formation of a shock wave and in this way enable control of the rock burst phenomenon to be achieved. When σ = σ(∂ɛ/∂t), the conditions for the generation of a shock wave do not exist.

History of X‐Ray Transients as Seen by Vela, 1969–1979a

During the 10-year lifetime of the x-ray detectors, the Vela spacecraft provided data on many new types of sources. Cen X-4, an exceedingly bright x-ray transient, was observed in the summer of 1969, shortly after launch, and did not return to the x-ray sky until May 1979, when it was again observed by Vela 5B. This source also produced the first of many x-ray bursts detected by Vela, the bright, hard, precursor observed on 7 July 1969. The vela gamma-ray detectors revealed the new phenomenon of gamma-ray bursts. It has recently been found that at least two gamma-ray bursts were also detected by the x-ray counters. The data produced by Vela 5B over the 7-year period May 1969 - June 1976, during which real-time tracking was reasonably complete, have been put into the form of a series of 10-day x-ray sky maps. Although the Vela x-ray detectors were relatively small (27 cm/sup 2/ effective area), they were sensitive enough to yield good data on Cen A (NCC 5128) during the period 1973-1975 when it was unusually bright and active. The Vela data show that Cen A often changed dramatically in intensity in less than 10 days. 11 references.

Strain bursts in pure copper subjected to various forms of static and cyclic loading at ambient temperature

The phenomenon of strain bursts has been discovered in pure polycrystalline copper subjected to cyclic or static creep, cyclic incremental tension and cyclic tension-compression. In cyclic creep, bursts appear over the stress range 0.5–0.8 of the ultimate tensile strength. The threshold stress for cyclic creep is much lower than this, however, and the lower limit for the appearance of bursts is believed to be dictated by the sensitivity of the apparatus used to detect them. Bursts can be produced in exaggerated form by slight increments of stress when the material has reached a saturated state. The bursts were usually observed to be more pronounced the higher the stress level. The mechanism of the strain bursts is discussed. They are shown not to be caused by dynamic strain aging (due to an impurity, say, such as oxygen). Their mechanism is also different in detail from that of the bursts observed by Neumann because the dislocation structures are different. We conclude that they are caused purely by dislocation locking and the subsequent sudden collapse of the locking mechanism.

An opponent-process interpretation of postshock bursts in appetitive responding

While eight food-deprived rats pressed a lever for food during daily 1-h sessions, four CS-Shock2 trials were presented. Trials were preceded by either a Shock1 of .25, .50, .75 mA or no Shock1. It was found that the rate of appetitive responding during the CS was greater on Shock1-CS-Shock2 trials relative to CS-Shock2 trials. The data indicate that the phenomenon of postshock bursts in responding can occur in the absence of a signal for safety after shock. The results conform to the predictions of the opponent-process theory of motivation.

Types of neuronal responses in the rat thalamus to peripheral temperature changes

Recordings were made of spike-trains from 163 neurons of the rostral part of the ventrobasal thalamus complex of the rat while the temperature of the scrotal skin was altered. The following results were obtained: 55 neurons were non-thermosensitive, 7 neurons cold-sensitive and 101 neurons warm-sensitive. In the case of the warm-sensitive cells a definite discrimination was possible: 61.4% of the neurons altered their firing behavior during peripheral cooling, changing from relatively even spike frequency to burst firing. This change could be induced repeatedly by altering the temperature. 38.6% of the neurons, on the other hand, reacted to cooling by slowing down their frequency. By way of statistical methods the firing patterns of the two response-types were analyzed more precisely and the differences in response to temperature stimuli more exactly defined. Likewise, the spatial distribution of the two response-types of warm-sensitive cells exhibited differences; whereas the cells devoid of burst activity occured rather uniformly in the region of the thalamus studied, the cells with bursting activity were confined more to the mediocaudal region. These findings are discussed with regard to the phenomenon of peripheral bursts and to the projection of thermoafferent pathways onto the ventrobasal thalamus complex. The functional interpretation of the various cell reactions and their role in the central processing of thermoafferent signals still remains unexplained and requires comparative studies of peripheral and central parts of the thermoafferent system.

Current noise in thin gold films

Measurements have been made of the current noise in gold films deposited on glass substrates with surface resistivities in the range 10 to 104 Ω/sq. The experimental results have shown that the spectral noise power density may be expressed by where I is the direct current flowing through a gold film of surface resistance R at a temperature T, f is the noise-channel frequency, F(T) is a function of T and G(S) is a function of film structure. Observations have also been made on the phenomenon of noise bursts. The experimental data are interpreted in terms of a trap-assisted tunnelling conduction mechanism with a range of barrier widths. Further support is given to the proposed model from current-noise measurements made on cermet films.