Energy Release Parameters Research Articles

Modeling energy release parameters in stochastic simulation of ground motions generated by Vrancea intermediate-depth seismic source

Ground motion time-domain stochastic simulations are performed by generating a white or a Gaussian noise, shaping it with a window, loading its normalized spectrum with the spectrum of the motion at a specific site and transforming it back in time-domain (Boore in Pure Appl Geophys 160: 635–676, 2003). The outcome of the resulted simulations is compared to the target parameters, namely amplitude, frequency content and duration parameters. Using SMSIM (Boore in SMSIM: Fortran programs for simulating ground motions form earthquakes, 2005) and EXSIM (Motazedian and Atkinson in Bull Seismol Soc Am 95(3): 995–1010, 2005. https://doi.org/10.1785/0120030207), Coțovanu (J Mil Technol 1(2): 27–32, 2018. https://doi.org/10.32754/jmt.2018.2.05) and Coțovanu and Vacareanu (J Seismol 24(1): 229–241, 2020. https://doi.org/10.1007/s10950-019-09892-5) applied the stochastic simulation method for generating ground motions produced by intermediate-depth Vrancea (Romania) earthquakes and found inconsistent results for duration parameters (significant duration and energy distribution in time-domain). In simulations, the duration of the motion results from the source and path duration, but the significant duration (that contains 90% of the energy) depends on the way the energy is distributed in time, and this distribution is controlled through a noise shaping window. The objective of this paper is to provide an appropriate form of the shaping window that can describe the specific energy release of ground motions generated by Vrancea intermediate depth seismic source (the first 50–70% of energy being rapidly released, the rest of it having a very slow release). For this matter, 371 recorded motions were analyzed and 5 types of energy release were defined. The set with the above described pattern that contained almost half of the analyzed accelerograms was used to define a mean normalized cumulative energy that describes the Vrancea specificity. On this basis, the parameters for the SMSIM implemented exponential window were determined and, because the results were inconsistent, a more adequate window function was defined and implemented in SMSIM. For the newly defined two-interval window function an algorithm for calculating the parameters was described, and the parameters of the mean release of energy were determined. By using the two-interval function for describing the Vrancea specific release of energy, more appropriate ground motion simulations resulted.

Thermal-spikes temperature measurement in pure metals under argon ion irradiation (E = 5-15 keV)

A method for determining the parameters of energy release in dense cascades of atomic displacements and for estimating the temperature and the level of pressures in thermalized cascade regions (thermal spikes) is proposed. It is based on the measurement and analysis of the spectral composition of the surface glow of condensed media in the course of irradiation with Ar+ 5-15 keV accelerated ions, under the assumption of the presence of a thermal component of glow defined by the presence of thermalized cascade regions.

Anomalies associated with energy release parameters for cracks in piezoelectric materials

For a central crack in a piezoelectric plate, the mode-I stress intensity factor ( K I ), electric displacement intensity factor ( K D ), energy release rates ( G, G M ) and energy density factor ( S) are obtained from the finite element results. For the impermeable crack, the numerical results of K I and K D are coupled; this error is contrary to the uncoupled analytical solutions. The error has little effect on the total energy release rate G and energy density factor S, but in some cases, large errors in the mechanical energy release rate G M are observed. G is global while SED is local. Also G is negative which defies physics where energy cannot be created while crack attempts to extend as implied by G. Computations should be made for the J-integral and also show that J becomes negative. What this shows is that the global fracture energy criterion is not suitable to address the local release of energy because it includes the overall energy which are irrelevant to fracture initiation being a local behavior. In addition, the case study shows that the energy density theory is the better fracture criterion for the piezoelectric material. According to the results of S, it retards the crack growth when the external electric field and piezoelectric poling are on opposite directions. This conclusion agrees with analytical and experimental evidence in the past references.

Correlations between the development of a flare in the Blazar 3C 454.3 in the radio and optical

Radio and optical data are used to analyze the development of the flare in the blazar 3C 454.3 observed in 2004–2007. A detailed correspondance between the optical and radio flares is established, with a time delay that depends on the observing frequency. The variation of the delay of the radio flare relative to the optical flare is opposite to the dispersion delay expected for the propagation of radiation in the interstellar medium, testifying to an intrinsic origin for the observed outburst. Small-scale flux variations on time intervals of 5–10 days in the millimeter and optical are also correlated, with a time delay of about ten months. This may provide evidence for a single source generating the radiation at all wavelengths. Rapid flux fluctuations in the radio and optical that are correlated with the indicated time delays could be associated with inhomogeneities in the accretion disk. Detailed studies of the flux variations of Active Galactic Nuclei (AGN) can be used to analyze the structure of the accretion disk. A model for the energy release in AGN that is not associated purely with accretion onto supermassive black holes is proposed. As is the case for other active members of the AGN family, estimates of the lifetime of the binary black-hole system in 3C 454.3 suggest that this object is in a stage of its evolution that is fairly close to the coalescence of its black holes. The energy that is released as the companion of the central black hole loses orbital angular momentum is sufficient to explain the observed AGN phenomena. The source of primary energy release could be heating of the gas behind shock fronts that arise due to the friction between the companion black hole and the ambient gaseous medium. The orbit of the companion could be located at the periphery of the accretion disk of the central body at its apocenter and plunge more deeply into the accretion disk at its pericenter, inducing flares at all wavelengths. Energy-release parameters such as the temperature and density of the heated gas are estimated for 3C 454.3. The model considered assumes omnidirectional radiation of the medium in the presence of a magnetic field. The radiation corresponding to the minimum flux level (base level) could represent omnidirectional radiation due to the orbit of the moving companion. The fraction of the energy that is transferred to directed jets is small, comprising 1–2% of the total energy released due to the loss of orbital angular momentum by the companion.

Calorimetric and DSC studies of mitochondria isolated from cytoplasmic male sterile line of rice

In this paper, the thermogenesis and differential scanning calorimetry (DSC) curves of energy release of the mitochondria isolated from variant strains of cytoplasmic male sterile lines of rices have been determined by using an LKB2277 Bioactivity Monitor and a DuPont 910 differential scanning calorimeter. The regularity and characteristics of the energy release of the mitochondria at constant and changing temperature were investigated, the differences in shape of the curves and the thermodynamic and kinetic characteristics of the thermogenesis of the mitochondria were compared, the thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage were calculated, and the experimental thermokinetic equations describing the different thermogenesis processes were established.

Microcalorimetric studies on the thermogenesis of energy release of mitochondria isolated from rice

After isolation from rice mitochondria still have activity and can live for a long time by using its stored nutrients. The thermogenesis curves of energy release of the mitochondria isolated from variant strains of rice have been determined by using an LKB2277 bioactivity monitor. The differences in shape of the curves and the thermodynamic and kinetic characteristics of the thermogenesis of the mitochondria have been compared. The thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage have been calculated, and the experimental thermokinetic equations of the thermogenesis have been established.

Studies on the energy release of rice mitochondria under different conditions by means of microcalorimetry

The thermodynamic and kinetic behaviors of energy release of mitochondria isolated from rice (Oryza sative L.) were studied by using a LKB 2277 Bioactivity Monitor under different conditions. The thermogenesis curves of energy release of the rice mitochondria (which had been kept at 0–3°C for 15 h and 40 day before the determination) were determined respectively at 25 and 30°C, and the difference in shape of the thermogenesis curves and thermodynamic and kinetic characteristics were compared. The thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage have been calculated, and the experimental thermokinetic equations of the thermogenesis have been established. The results indicated that the lower the temperature, the slower the energy release of the rice mitochondria. Both the thermogenesis and the energy release rate of the rice mitochondria increased after the mitochondria was kept at lower temperature for 40 days. One can use the methods to characterize the ability of the rice mitochondria to release energy under different conditions.

Power Density Spectra of Gamma-Ray Bursts in the Internal Shock Model

We simulate Gamma-Ray Bursts arising from internal shocks in relativistic winds, calculate their power density spectrum (PDS), and identify the factors to which the PDS is most sensitive: the wind ejection features, which determine the wind dynamics and its optical thickness, and the energy release parameters, which give the pulse 50-300 keV radiative efficiency. For certain combinations of ejection features and wind parameters the resulting PDS exhibits the features observed in real bursts. We found that the upper limit on the efficiency of conversion of wind kinetic energy into 50-300 keV photons is $\sim$ 1%. Winds with a modulated Lorentz factor distribution of the ejecta yield PDSs in accord with current observations and have efficiencies closer to $10^{-3}$, while winds with a random, uniform Lorentz factor ejection must be optically thick to the short duration pulses to produce correct PDSs, and have an overall efficiency around $10^{-4}$.

Fractal structure and features of energy-release (combustion) processes in heterogeneous condensed systems

In this work, the theory of fractals has been used to describe the structure of heterogeneous condensed systems (HCS). Features of energy-release processes with variation of the initial structure parameters have been investigated. The microstructure of HCS and the dynamics of its change have been studied as functions of the proportion and properties of their components. It is shown that particles of the components form fractal structures, which are characterized by fractional dimensions. The obtained images of the microstructure reflect the presence of the geometric phase transition “fractal cluster-percolation cluster.” Regularities of reaction-front propagation are determined. It is found that the concentration limits of energy release and combustion are associated with the evolution of fractal structures and the formation (disruption) of a continuous reaction surface. The electrical conductivity of the starting compositions is measured as an indicator of the formation of fractal structures of one or another configuration. Electrical and thermal-physics properties of the samples and energy-release (combustion) parameters are analyzed. The systems exhibit similar behavior in different processes. Near the critical point, the dependence of the parameters studied on concentration has an exponential character. The exponent is close to that determined in percolation theory. A computational algorithm for the contact surface of the components is developed and implemented. The computation results allow one to distinguish the “base block” that influences the combustion rate and to determine the critical concentrations of the components. The study of HCS in the context of the new direction in the geometry of disordered systems—the theory of fractals—is promising for generalization of available experimental data and for predicting the parameters of energy release in HCS with variation in the structural parameters.

THE STRUCTURE OF DETONATION WAVES

Multidimensional time-dependent numerical simulations have been used to study the initiation, propagation, and extinction of detonations in gases and liquids. The simulations, which calculate the detailed behavior of the interacting shock waves and reaction zones forming the detonation wave, are used to study the evolution of the instability that leads to the cellular structure of detonations. The simulations consist of two-dimensional time-dependent solutions of the convection of mass density, momentum density and energy coupled to models for chemical energy release. The convective transport equations are solved by the Flux-Corrected Transport algorithm. The chemical reactions and energy release are usually modelled by the two-step induction parameter model. We conclude that the behavior of the multidimensional structure of a detonation depends on the differences of the thermodynamic properties in the inductiori zones behind the Mach stem and the incident shock. The formation of unreacted pockets behind the detonation front depends on the inclination of the transverse waves and the curvature of the shock fronts. Highly curved fronts may result in large pockets. The temperature dependence of the induction time is a major factor in the regularity of detonation structure. Detonation structure is affected by the energy release parameters. Instantaneous energy release leads to one-dimensional structures. Fast energy release results in less regular structures. Very slow energy release results in large pockets, highly curved fronts, and the detonation may die out. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987406

Effects of Isotopic Abundance on Kerma in Naturally Occurring Targets: Chlorine

To calculate the neutron kinetic energy release parameters (kerma factors) for an element consisting of several isotopes, it is necessary to use separate neutron cross-section and radioactive decay data for each isotope. In the case of chlorine, cross sections for natural chlorine are available, but cross sections for the individual isotopes are not. Kerma factors for chlorine were calculated using natural chlorine cross sections and weighting the contribution of each isotope to the decay data, by using the fractional contribution as a variable parameter. The kerma factors calculated at particular neutron energies are found to be sensitive to this parameter and dependent on that energy. The purpose of this Note is to encourage experimental determination of the relevant neutron cross sections of isotopically pure samples of chlorine. 2 figures, 3 tables.