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Sample records for adiabatic blast wave

  1. Relativistic blast waves in two dimensions. I - The adiabatic case

    NASA Technical Reports Server (NTRS)

    Shapiro, P. R.

    1979-01-01

    Approximate solutions are presented for the dynamical evolution of strong adiabatic relativistic blast waves which result from a point explosion in an ambient gas in which the density varies both with distance from the explosion center and with polar angle in axisymmetry. Solutions are analytical or quasi-analytical for the extreme relativistic case and numerical for the arbitrarily relativistic case. Some general properties of nonplanar relativistic shocks are also discussed, including the incoherence of spherical ultrarelativistic blast-wave fronts on angular scales greater than the reciprocal of the shock Lorentz factor, as well as the conditions for producing blast-wave acceleration.

  2. Some properties of adiabatic blast waves in preexisting cavities

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Franco, J.

    1981-01-01

    Cox and Anderson (1982) have conducted an investigation regarding an adiabatic blast wave in a region of uniform density and finite external pressure. In connection with an application of the results of the investigation to a study of interstellar blast waves in the very hot, low-density matrix, it was found that it would be desirable to examine situations with a positive radial density gradient in the ambient medium. Information concerning such situations is needed to learn about the behavior of blast waves occurring within preexisting, presumably supernova-induced cavities in the interstellar mass distribution. The present investigation is concerned with the first steps of a study conducted to obtain the required information. A review is conducted of Sedov's (1959) similarity solutions for the dynamical structure of any explosion in a medium with negligible pressure and power law density dependence on radius.

  3. The dynamic instability of adiabatic blast waves

    NASA Technical Reports Server (NTRS)

    Ryu, Dongsu; Vishniac, Ethan T.

    1991-01-01

    Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.

  4. Extended adiabatic blast waves and a model of the soft X-ray background. [interstellar matter

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Anderson, P. R.

    1981-01-01

    An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.

  5. Extended adiabatic blast waves and a model of the soft X-ray background

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Anderson, P. R.

    1982-01-01

    The suggestion has been made that much of the soft X-ray background observed in X-ray astronomy might arise from being inside a very large supernova blast wave propagating in the hot, low-density component of the interstellar (ISM) medium. An investigation is conducted to study this possibility. An analytic approximation is presented for the nonsimilar time evolution of the dynamic structure of an adiabatic blast wave generated by a point explosion in a homogeneous ambient medium. A scheme is provided for evaluating the electron-temperature distribution for the evolving structure, and a procedure is presented for following the state of a given fluid element through the evolving dynamical and thermal structures. The results of the investigation show that, if the solar system were located within a blast wave, the Wisconsin soft X-ray rocket payload would measure the B and C band count rates that it does measure, provided conditions correspond to the values calculated in the investigation.

  6. Isothermal blast wave model of supernova remnants

    NASA Technical Reports Server (NTRS)

    Solinger, A.; Buff, J.; Rappaport, S.

    1975-01-01

    The validity of the 'adiabatic' assumption in supernova-remnant calculations is examined, and the alternative extreme of an isothermal blast wave is explored. It is concluded that, because of thermal conductivity, the large temperature gradients predicted by the adiabatic model probably are not maintained in nature. Self-similar solutions to the hydrodynamic equations for an isothermal blast wave have been found and studied. These solutions are then used to determine the relationship between X-ray observations and inferred parameters of supernova remnants. A comparison of the present results with those for the adiabatic model indicates differences which are less than present observational uncertainties. It is concluded that most parameters of supernova remnants inferred from X-ray measurements are relatively insensitive to the specifics of the blast-wave model.

  7. Blast wave energy diagnostic.

    PubMed

    Tierney, Thomas E; Tierney, Heidi E; Idzorek, George C; Watt, Robert G; Peterson, Robert R; Peterson, Darrell L; Fryer, Christopher L; Lopez, Mike R; Jones, Michael C; Sinars, Daniel; Rochau, Gregory A; Bailey, James E

    2008-10-01

    The distance radiation waves that supersonically propagate in optically thick, diffusive media are energy sensitive. A blast wave can form in a material when the initially diffusive, supersonic radiation wave becomes transonic. Under specific conditions, the blast wave is visible with radiography as a density perturbation. [Peterson et al., Phys. Plasmas 13, 056901 (2006)] showed that the time-integrated drive energy can be measured using blast wave positions with uncertainties less than 10% at the Z Facility. In some cases, direct measurements of energy loss through diagnostic holes are not possible with bolometric and x-ray radiometric diagnostics. Thus, radiography of high compression blast waves can serve as a complementary technique that provides time-integrated energy loss through apertures. In this paper, we use blast waves to characterize the energy emerging through a 2.4 mm aperture and show experimental results in comparison to simulations. PMID:19044574

  8. Curved characteristics behind blast waves.

    NASA Technical Reports Server (NTRS)

    Laporte, O.; Chang, T. S.

    1972-01-01

    The behavior of nonisentropic flow behind a propagating blast wave is theoretically studied. Exact solutions, expressed in closed form in terms of elementary functions, are presented for three sets of curved characteristicseind a self-similar, strong blast wave.

  9. Investigation of ultrafast laser-driven radiative blast waves.

    PubMed

    Edwards, M J; MacKinnon, A J; Zweiback, J; Shigemori, K; Ryutov, D; Rubenchik, A M; Keilty, K A; Liang, E; Remington, B A; Ditmire, T

    2001-08-20

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1/2 (for a cylinder), an effect expected when the blast wave loses energy by radiative cooling. Despite significant radiative cooling, the blast waves do not appear to develop thin shell instabilities expected for strongly radiative waves. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from electron thermal conduction effects. PMID:11497951

  10. Astrophysical blast wave data

    SciTech Connect

    Riley, Nathan; Geissel, Matthias; Lewis, Sean M; Porter, John L.

    2015-03-01

    The data described in this document consist of image files of shadowgraphs of astrophysically relevant laser driven blast waves. Supporting files include Mathematica notebooks containing design calculations, tabulated experimental data and notes, and relevant publications from the open research literature. The data was obtained on the Z-Beamlet laser from July to September 2014. Selected images and calculations will be published as part of a PhD dissertation and in associated publications in the open research literature, with Sandia credited as appropriate. The authors are not aware of any restrictions that could affect the release of the data.

  11. Blast wave stability in a non-ideal gas

    NASA Astrophysics Data System (ADS)

    Ktitorov, Vladimir

    1999-06-01

    Problem of stability of a selfsimilar blast wave in a non-ideal gas is considered. Small non-radial blast wave perturbations are expanded to spherical harmonics components of expansion being represented in a selfsimilar form (The perturbation front amplitudes are supposed to be power functions of time with power exponent being complex number). The spherical and cylindrical blast waves are considered in the unified manner. The adiabatic exponent of the non-ideal gas is supposed to be a function of the gas density. The blast wave in that gas is selfsimilar just like that is in the case of the ideal gas. So the selfsimilar approach to the blast wave stability problem is used that was previously used in the case of blast wave in ideal gas (Ref.1-3). We considered gas adiabatic exponent to be a simple one-parameter analytical function of density the value of parameter defining the level of gas non-ideality: from ideal gas to non- compressing liquid. For each level of non-ideality the stability problem is solved both for spherical and cylindrical blast waves. The instability region is determined in the space of parameters of the problem: harmonic number and parameters of gas equation of state. The crytical values of parameters of equation of state are calculated. The results are calculated numerically in the general case of arbitrary gas adiabatic exponent γ and harmonic number n and analytically in some special cases: n=1, n>>1, and (γ-1) << 1. 1. V.Ktitorov, Voprosy Atomnoi Nauki i Tekhniki (Atomic science and techn. issues), Ser.TPF, No2, p.28, (1984); 2. D.Ryu and E.T.Vishniac, Astr.J, 313, p.820 (1987); 3. V.Ktitorov, Khimich. Fizika (Chem Phys Issues) V.14, No 2-3, p.169, (1995);

  12. Blast waves with cosmic rays

    NASA Astrophysics Data System (ADS)

    Arbutina, B.

    2015-04-01

    Blast waves appear in many astrophysical phenomena, such as supernovae. In this paper we discuss blast waves with cosmic rays, i.e., with a component with a power-law number density distribution function N( p) ∝ p -Γ that may be particulary important in describing the evolution of supernova remnants. We confirm some previous findings that a significant amount of cosmic ray energy is deposited towards the center of a remnant.

  13. Blast waves in rotating media.

    NASA Technical Reports Server (NTRS)

    Rossner, L. F.

    1972-01-01

    The model investigated involves a cylindrically symmetric blast wave generated by an infinitely long line explosion in a cold and homogeneous gas rotating rigidly in its self-gravitational field. It is found that within the context of rotation in a gravitational field a blast wave will not adopt the one-zone form familiar from similarity solutions but, rather, a two-zone form. The inner compression zone arises as a response to the presence of the restoring force, which drives a rarefaction wave into the outer compression zone.

  14. Adiabatic nonlinear waves with trapped particles. III. Wave dynamics

    SciTech Connect

    Dodin, I. Y.; Fisch, N. J.

    2012-01-15

    The evolution of adiabatic waves with autoresonant trapped particles is described within the Lagrangian model developed in Paper I, under the assumption that the action distribution of these particles is conserved, and, in particular, that their number within each wavelength is a fixed independent parameter of the problem. One-dimensional nonlinear Langmuir waves with deeply trapped electrons are addressed as a paradigmatic example. For a stationary wave, tunneling into overcritical plasma is explained from the standpoint of the action conservation theorem. For a nonstationary wave, qualitatively different regimes are realized depending on the initial parameter S, which is the ratio of the energy flux carried by trapped particles to that carried by passing particles. At S < 1/2, a wave is stable and exhibits group velocity splitting. At S > 1/2, the trapped-particle modulational instability (TPMI) develops, in contrast with the existing theories of the TPMI yet in agreement with the general sideband instability theory. Remarkably, these effects are not captured by the nonlinear Schroedinger equation, which is traditionally considered as a universal model of wave self-action but misses the trapped-particle oscillation-center inertia.

  15. Adiabatic continuity, wave-function overlap, and topological phase transitions

    NASA Astrophysics Data System (ADS)

    Gu, Jiahua; Sun, Kai

    2016-09-01

    In this paper, we study the relation between wave-function overlap and adiabatic continuity in gapped quantum systems. We show that for two band insulators, a scalar function can be defined in the momentum space, which characterizes the wave-function overlap between Bloch states in the two insulators. If this overlap is nonzero for all momentum points in the Brillouin zone, these two insulators are adiabatically connected, i.e., we can deform one insulator into the other smoothly without closing the band gap. In addition, we further prove that this adiabatic path preserves all the symmetries of the insulators. The existence of such an adiabatic path implies that two insulators with nonzero wave-function overlap belong to the same topological phase. This relation, between adiabatic continuity and wave-function overlap, can be further generalized to correlated systems. The generalized relation cannot be applied to study generic many-body systems in the thermodynamic limit, because of the orthogonality catastrophe. However, for certain interacting systems (e.g., quantum Hall systems), the quantum wave-function overlap can be utilized to distinguish different quantum states. Experimental implications are also discussed.

  16. A SEMI-ANALYTIC FORMULATION FOR RELATIVISTIC BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    SciTech Connect

    Uhm, Z. Lucas

    2011-06-01

    This paper performs a semi-analytic study of relativistic blast waves in the context of gamma-ray bursts. Although commonly used in a wide range of analytical and numerical studies, the equation of state (EOS) with a constant adiabatic index is a poor approximation for relativistic hydrodynamics. Adopting a more realistic EOS with a variable adiabatic index, we present a simple form of jump conditions for relativistic hydrodynamical shocks. Then we describe in detail our technique of modeling a very general class of GRB blast waves with a long-lived reverse shock. Our technique admits an arbitrary radial stratification of the ejecta and ambient medium. We use two different methods to find dynamics of the blast wave: (1) customary pressure balance across the blast wave and (2) the 'mechanical model'. Using a simple example model, we demonstrate that the two methods yield significantly different dynamical evolutions of the blast wave. We show that the pressure balance does not satisfy the energy conservation for an adiabatic blast wave while the mechanical model does. We also compare two sets of afterglow light curves obtained with the two different methods.

  17. Laboratory blast wave driven instabilities

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn

    2008-11-01

    This presentation discusses experiments involving the evolution of hydrodynamic instabilities in the laboratory under high-energy-density (HED) conditions. These instabilities are driven by blast waves, which occur following a sudden, finite release of energy, and consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. Instabilities evolving under HED conditions are relevant to astrophysics. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 μm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses an interface having a 2D or 3D sinusoidal structure that serves as a seed perturbation for hydrodynamic instabilities. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability in the nonlinear regime. We have detected the interface structure under these conditions using x-ray backlighting. Recent advances in our diagnostic techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed or predicted by current simulations. The observed effect is potentially of great importance as a source of mass transport to places not anticipated by current theory and simulation. I will discuss the amount of mass in these spike extensions, the associated uncertainties, and hypotheses regarding their origin We also plan to show comparisons of experiments using single mode and multimode as well as 2D and 3D initial conditions. This work is sponsored by DOE/NNSA Research Grants DE-FG52-07NA28058 (Stewardship Sciences Academic Alliances) and DE-FG52-04NA00064 (National Laser User

  18. Simulation of Blast Waves with Headwind

    NASA Technical Reports Server (NTRS)

    Olsen, Michael E.; Lawrence, Scott W.; Klopfer, Goetz H.; Mathias, Dovan; Onufer, Jeff T.

    2005-01-01

    The blast wave resulting from an explosion was simulated to provide guidance for models estimating risks for human spacecraft flight. Simulations included effects of headwind on blast propagation, Blasts were modelled as an initial value problem with a uniform high energy sphere expanding into an ambient field. Both still air and cases with headwind were calculated.

  19. Blast wave parameters at diminished ambient pressure

    NASA Astrophysics Data System (ADS)

    Silnikov, M. V.; Chernyshov, M. V.; Mikhaylin, A. I.

    2015-04-01

    Relation between blast wave parameters resulted from a condensed high explosive (HE) charge detonation and a surrounding gas (air) pressure has been studied. Blast wave pressure and impulse differences at compression and rarefaction phases, which traditionally determine damage explosive effect, has been analyzed. An initial pressure effect on a post-explosion quasi-static component of the blast load has been investigated. The analysis is based on empirical relations between blast parameters and non-dimensional similarity criteria. The results can be directly applied to flying vehicle (aircraft or spacecraft) blast safety analysis.

  20. Instability of Taylor-Sedov blast waves propagating through a uniform gas

    NASA Astrophysics Data System (ADS)

    Grun, J.; Stamper, J.; Manka, C.; Resnick, J.; Burris, R.

    1991-05-01

    An instability in Taylor-Sedov blast waves was measured as the waves propagated through a uniform gas with a low adiabatic index. The first measurements of the instability are given and compared to theoretical predictions. The classical Taylor-Sedov blast waves resulted from the expansion of ablation plasma into an ambient gas from laser-irradiated foils, and photographs were taken using the dark-field imaging method. Visible emission from the blasts were recorded with a four-frame microchannel-plate intensifier camera. Blast waves formed in nitrogen gas are shown to be stable and smooth, whereas the waves propagating through xenon gas are found to be unstable and wrinkled. A power law is fitted to the experimental data, and the adiabatic indices are theorized to cause the different responses in the two gases. The results generally agree with theoretical predictions in spite of some minor discrepancies, and an explanation of the instability mechanism is developed. When the adiabatic index is sufficiently low, the Taylor-Sedov blast waves in a uniform gas will be unstable, and the perturbed amplitudes will grow as a power of time.

  1. Adiabatic theory of solitons fed by dispersive waves

    NASA Astrophysics Data System (ADS)

    Pickartz, Sabrina; Bandelow, Uwe; Amiranashvili, Shalva

    2016-09-01

    We consider scattering of low-amplitude dispersive waves at an intense optical soliton which constitutes a nonlinear perturbation of the refractive index. Specifically, we consider a single-mode optical fiber and a group velocity matched pair: an optical soliton and a nearly perfectly reflected dispersive wave, a fiber-optical analog of the event horizon. By combining (i) an adiabatic approach that is used in soliton perturbation theory and (ii) scattering theory from quantum mechanics, we give a quantitative account of the evolution of all soliton parameters. In particular, we quantify the increase in the soliton peak power that may result in the spontaneous appearance of an extremely large, so-called champion soliton. The presented adiabatic theory agrees well with the numerical solutions of the pulse propagation equation. Moreover, we predict the full frequency band of the scattered dispersive waves and explain an emerging caustic structure in the space-time domain.

  2. Cygnus Loop Supernova Blast Wave

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This is an image of a small portion of the Cygnus Loop supernova remnant, which marks the edge of a bubble-like, expanding blast wave from a colossal stellar explosion, occurring about 15,000 years ago. The HST image shows the structure behind the shock waves, allowing astronomers for the first time to directly compare the actual structure of the shock with theoretical model calculations. Besides supernova remnants, these shock models are important in understanding a wide range of astrophysical phenomena, from winds in newly-formed stars to cataclysmic stellar outbursts. The supernova blast is slamming into tenuous clouds of insterstellar gas. This collision heats and compresses the gas, causing it to glow. The shock thus acts as a searchlight revealing the structure of the interstellar medium. The detailed HST image shows the blast wave overrunning dense clumps of gas, which despite HST's high resolution, cannot be resolved. This means that the clumps of gas must be small enough to fit inside our solar system, making them relatively small structures by interstellar standards. A bluish ribbon of light stretching left to right across the picture might be a knot of gas ejected by the supernova; this interstellar 'bullet' traveling over three million miles per hour (5 million kilometres) is just catching up with the shock front, which has slowed down by ploughing into interstellar material. The Cygnus Loop appears as a faint ring of glowing gases about three degrees across (six times the diameter of the full Moon), located in the northern constellation, Cygnus the Swan. The supernova remnant is within the plane of our Milky Way galaxy and is 2,600 light-years away. The photo is a combination of separate images taken in three colors, oxygen atoms (blue) emit light at temperatures of 30,000 to 60,000 degrees Celsius (50,000 to 100,000 degrees Farenheit). Hydrogen atoms (green) arise throughout the region of shocked gas. Sulfur atoms (red) form when the gas cools to

  3. Adiabatic corrections to density functional theory energies and wave functions.

    PubMed

    Mohallem, José R; Coura, Thiago de O; Diniz, Leonardo G; de Castro, Gustavo; Assafrão, Denise; Heine, Thomas

    2008-09-25

    The adiabatic finite-nuclear-mass-correction (FNMC) to the electronic energies and wave functions of atoms and molecules is formulated for density-functional theory and implemented in the deMon code. The approach is tested for a series of local and gradient corrected density functionals, using MP2 results and diagonal-Born-Oppenheimer corrections from the literature for comparison. In the evaluation of absolute energy corrections of nonorganic molecules the LDA PZ81 functional works surprisingly better than the others. For organic molecules the GGA BLYP functional has the best performance. FNMC with GGA functionals, mainly BLYP, show a good performance in the evaluation of relative corrections, except for nonorganic molecules containing H atoms. The PW86 functional stands out with the best evaluation of the barrier of linearity of H2O and the isotopic dipole moment of HDO. In general, DFT functionals display an accuracy superior than the common belief and because the corrections are based on a change of the electronic kinetic energy they are here ranked in a new appropriate way. The approach is applied to obtain the adiabatic correction for full atomization of alcanes C(n)H(2n+2), n = 4-10. The barrier of 1 mHartree is approached for adiabatic corrections, justifying its insertion into DFT. PMID:18537228

  4. On the Propagation and Interaction of Spherical Blast Waves

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Freeman, Robert

    2007-01-01

    The characteristics and the scaling laws of isolated spherical blast waves have been briefly reviewed. Both self-similar solutions and numerical solutions of isolated blast waves are discussed. Blast profiles in the near-field (strong shock region) and the far-field (weak shock region) are examined. Particular attention is directed at the blast overpressure and shock propagating speed. Consideration is also given to the interaction of spherical blast waves. Test data for the propagation and interaction of spherical blast waves emanating from explosives placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure.

  5. Self-similar blast waves incorporating deflagrations of variable speed

    NASA Technical Reports Server (NTRS)

    Guirguis, R. H.; Kamel, M. M.; Oppenheim, A. K.

    1983-01-01

    The present investigation is concerned with the development of a systematic approach to the problem of self-similar blast waves incorporating nonsteady flames. The regime covered by the presented solutions is bounded on one side by an adiabatic strong explosion and, on the other, by deflagration propagating at an infinite acceleration. Results for a representative set of accelerations are displayed, taking into account the full range of propagation speeds from zero to velocities corresponding to the Chapman-Jouguet deflagration. It is found that the distribution of stored energy in the undisturbed medium determines the acceleration of the deflagration-shock wave system. The obtained results reveal the existence of a simple relation between the location of the deflagration and its Mach number.

  6. The blast wave mitigation effects of a magnetogasdynamic decelerator

    SciTech Connect

    Baty, Roy S; Lundgren, Ronald G; Tucker, Don H

    2009-01-01

    This work computes shock wave jump functions for viscous blast waves propagating in a magnetogasdynamic decelerator. The decelerator is assumed to be a one-dimensional channel with sides that are perfect conductors. An electric field applied on the walls of the channel produces a magnetogasdynamic pump, which decelerates the flow field induced by a blast wave. The blast wave jump functions computed here are compared to magnetogasdynamic results for steady supersonic channel flow to quantify potential blast mitigation effects. Theoretical shock wave jump functions are also presented for inviscid blast waves propagating in a one-dimensional channel with an electromagnetic field.

  7. Computation of blast wave-obstacle interactions

    NASA Technical Reports Server (NTRS)

    Champney, J. M.; Chaussee, D. S.; Kutler, P.

    1982-01-01

    Numerical simulations of the interaction of a planar blast wave with various obstacles are presented. These obstacles are either ground structures or vehicles flying in the atmosphere. For a structure on the ground, the blast wave encounter is side-on, while for the flying vehicles the encounter is either head-on or oblique. Second-order accurate, finite-difference, and shock-capturing procedures are employed to solve the two-dimensional, axisymmetric, and three-dimensional unsteady Euler equations. Results are presented for the flow field consisting of blast wave striking obstacles that are at rest, moving subsonically and moving supersonically. Comparison of the numerical results with experimental data for a configuration at rest substantiates the validity of this approach and its potential as a flow analysis tool.

  8. The time development of a blast wave with shock heated electrons

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.; Cox, D. P.

    1983-01-01

    Accurate approximations are presented for the time development of both edge conditions and internal structures of a blast wave with shock heated electrons, and equal ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform ambient density case) and have negligible external pressure. Account is taken of possible saturation of the thermal conduction flux. The structures evolve smoothly to the adiabatic structures.

  9. The time development of a blast wave with shock-heated electrons

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.; Cox, D. P.

    1984-01-01

    Accurate approximations are presented for the time development of both edge conditions and internal structures of a blast wave with shock heated electrons, and equal ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform ambient density case) and have negligible external pressure. Account is taken of possible saturation of the thermal conduction flux. The structures evolve smoothly to the adiabatic structures.

  10. Blast wave mitigation by dry aqueous foams

    NASA Astrophysics Data System (ADS)

    Del Prete, E.; Chinnayya, A.; Domergue, L.; Hadjadj, A.; Haas, J.-F.

    2013-02-01

    This paper presents results of experiments and numerical modeling on the mitigation of blast waves using dry aqueous foams. The multiphase formalism is used to model the dry aqueous foam as a dense non-equilibrium two-phase medium as well as its interaction with the high explosion detonation products. New experiments have been performed to study the mass scaling effects. The experimental as well as the numerical results, which are in good agreement, show that more than an order of magnitude reduction in the peak overpressure ratio can be achieved. The positive impulse reduction is less marked than the overpressures. The Hopkinson scaling is also found to hold particularly at larger scales for these two blast parameters. Furthermore, momentum and heat transfers, which have the main dominant role in the mitigation process, are shown to modify significantly the classical blast wave profile and thereafter to disperse the energy from the peak overpressure due to the induced relaxation zone. In addition, the velocity of the fireball, which acts as a piston on its environment, is smaller than in air. Moreover, the greater inertia of the liquid phase tends to project the aqueous foam far from the fireball. The created gap tempers the amplitude of the transmitted shock wave to the aqueous foam. As a consequence, this results in a lowering of blast wave parameters of the two-phase spherical decaying shock wave.

  11. Blast waves and how they interact with structures.

    PubMed

    Cullis, I G

    2001-02-01

    The paper defines and describes blast waves, their interaction with a structure and its subsequent response. Explosions generate blast waves, which need not be due to explosives. A blast wave consists of two parts: a shock wave and a blast wind. The paper explains how shock waves are formed and their basic properties. The physics of blast waves is non-linear and therefore non-intuitive. To understand how an explosion generates a blast wave a numerical modelling computer code, called a hydrocode has to be employed. This is briefly explained and the cAst Eulerian hydrocode is used to illustrate the formation and propagation of the blast wave generated by a 1 kg sphere of TNT explosive detonated 1 m above the ground. The paper concludes with a discussion of the response of a structure to a blast wave and shows that this response is governed by the structures natural frequency of vibration compared to the duration of the blast wave. The basic concepts introduced are illustrated in a second simulation that introduces two structures into the blast field of the TNT charge. PMID:11307674

  12. Solitary shock waves and adiabatic phase transition in lipid interfaces and nerves

    NASA Astrophysics Data System (ADS)

    Shrivastava, Shamit; Kang, Kevin Heeyong; Schneider, Matthias F.

    2015-01-01

    This study shows that the stability of solitary waves excited in a lipid monolayer near a phase transition requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave's amplitude, and the splitting of the wave at the phase boundaries. Splitting in particular confirms that a hydrated lipid interface can undergo condensation on adiabatic heating, thus showing retrograde behavior. Finally, using the theoretical insights and state dependence of conduction velocity in nerves, the curvature of the adiabatic state diagram is shown to be closely tied to the thermodynamic blockage of nerve pulse propagation.

  13. Solitary shock waves and adiabatic phase transition in lipid interfaces and nerves.

    PubMed

    Shrivastava, Shamit; Kang, Kevin Heeyong; Schneider, Matthias F

    2015-01-01

    This study shows that the stability of solitary waves excited in a lipid monolayer near a phase transition requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave's amplitude, and the splitting of the wave at the phase boundaries. Splitting in particular confirms that a hydrated lipid interface can undergo condensation on adiabatic heating, thus showing retrograde behavior. Finally, using the theoretical insights and state dependence of conduction velocity in nerves, the curvature of the adiabatic state diagram is shown to be closely tied to the thermodynamic blockage of nerve pulse propagation.

  14. Low-Cost Blast Wave Generator for Studies of Hearing Loss and Brain Injury: Blast Wave Effects in Closed Spaces

    PubMed Central

    Newman, Andrew J.; Hayes, Sarah H.; Rao, Abhiram S.; Allman, Brian L.; Manohar, Senthilvelan; Ding, Dalian; Stolzberg, Daniel; Lobarinas, Edward; Mollendorf, Joseph C.; Salvi, Richard

    2015-01-01

    Background Military personnel and civilians living in areas of armed conflict have increased risk of exposure to blast overpressures that can cause significant hearing loss and/or brain injury. The equipment used to simulate comparable blast overpressures in animal models within laboratory settings is typically very large and prohibitively expensive. New Method To overcome the fiscal and space limitations introduced by previously reported blast wave generators, we developed a compact, low-cost blast wave generator to investigate the effects of blast exposures on the auditory system and brain. Results The blast wave generator was constructed largely from off the shelf components, and reliably produced blasts with peak sound pressures of up to 198 dB SPL (159.3 kPa) that were qualitatively similar to those produced from muzzle blasts or explosions. Exposure of adult rats to 3 blasts of 188 dB peak SPL (50.4 kPa) resulted in significant loss of cochlear hair cells, reduced outer hair cell function and a decrease in neurogenesis in the hippocampus. Comparison to existing methods Existing blast wave generators are typically large, expensive, and are not commercially available. The blast wave generator reported here provides a low-cost method of generating blast waves in a typical laboratory setting. Conclusions This compact blast wave generator provides scientists with a low cost device for investigating the biological mechanisms involved in blast wave injury to the rodent cochlea and brain that may model many of the damaging effects sustained by military personnel and civilians exposed to intense blasts. PMID:25597910

  15. Modeling of aqueous foam blast wave attenuation

    NASA Astrophysics Data System (ADS)

    Del Prete, E.; Chinnayya, A.; Hadjadj, A.; Domergue, L.; Haas, J.-F.; Imbert, B.

    The use of aqueous foams enables the mitigation of blast waves induced by the explosion of energetic materials. The two-phase confinement gives rise to interphase interactions between the gaseous and liquid phases, which role have been emphasized in shock-tube studies with solid foams [1, 2]. Multifluid formalism enables the thermo-mechanical disequilibria between phases to be taken into account. The flow model ensures the correct estimation of the acoustic impedance of the two-phase media. As for the numerical scheme, Riemann solvers are used to describe the microscopic fluid interactions, the summation of which provides the multiphase flux. The role of the different transfer mechanisms is evaluated in the case where the liquid ligaments of the foam matrix have been shattered into droplets by the shock impingement. Characteristics of blast waves in heterogeneous media leads to a decrease of overpressure. The numerical results have been compared favorably to experimental data [3, 4].

  16. Boundary-layer theory for blast waves

    NASA Technical Reports Server (NTRS)

    Kim, K. B.; Berger, S. A.; Kamel, M. M.; Korobeinikov, V. P.; Oppenheim, A. K.

    1975-01-01

    It is profitable to consider the blast wave as a flow field consisting of two regions: the outer, which retains the properties of the inviscid solution, and the inner, which is governed by flow equations including terms expressing the effects of heat transfer and, concomitantly, viscosity. The latter region thus plays the role of a boundary layer. Reported here is an analytical method developed for the study of such layers, based on the matched asymptotic expansion technique combined with patched solutions.

  17. Self-similar Ultrarelativistic Jetted Blast Wave

    NASA Astrophysics Data System (ADS)

    Keshet, Uri; Kogan, Dani

    2015-12-01

    Following a suggestion that a directed relativistic explosion may have a universal intermediate asymptotic, we derive a self-similar solution for an ultrarelativistic jetted blast wave. The solution involves three distinct regions: an approximately paraboloid head where the Lorentz factor γ exceeds ∼ 1/2 of its maximal, nose value; a geometrically self-similar, expanding envelope slightly narrower than a paraboloid; and an axial core in which the (cylindrically, henceforth) radial flow {{u}} converges inward toward the axis. Most (∼80%) of the energy lies well beyond the leading, head region. Here, a radial cross section shows a maximal γ (separating the core and the envelope), a sign reversal in {{u}}, and a minimal γ, at respectively ∼1/6, ∼1/4, and ∼3/4 of the shock radius. The solution is apparently unique, and approximately agrees with previous simulations, of different initial conditions, that resolved the head. This suggests that unlike a spherical relativistic blast wave, our solution is an attractor, and may thus describe directed blast waves such as in the external shock phase of a γ-ray burst.

  18. Biologic response to complex blast waves

    SciTech Connect

    Richmond, D.R.; Yelverton, J.T.; Fletcher, E.R.; Phillips, Y.Y.

    1985-01-01

    Small, bare charges were detonated inside an M59 armored personnel carrier (APC) in an attempt to simulate the complex blast waves generated by the jets from shaped-charge warheads penetrating into armored vehicles. Anesthetized sheep were placed inside the APC at 92- and 122-cm ranges from 57- or 113-g pentolite charges. Pressure-time was measured by pressure transducers either mounted on the animals or free standing at comparable ranges on the opposite side of the vehicle. In general, the waveforms were characterized by an initial shock wave of less than 1-msec duration followed by repeated reflections of decreasing magnitude. No deaths nor lung hemorrhages were observed, but all the animals sustained severe ear injury. Animals subjected to peak overpressures of 1.2 to 2.3 bar from the 113-g explosions also received slight non-auditory blast injuries to the upper respiratory and gastrointestinal tracts; those exposed to peak overpressures of just under 1 bar from the 57-g charges did not. The non-auditory blast injuries inside the APC were more severe than those sustained by sheep at comparable distances from 113-g charges in the open. The results suggested that the biological consequences of a complex wave of the type encountered in this study can be equated approximately to a Friedlander wave with a peak overpressure equal to that of the complex wave and with a total impulse equal to the impulse over the first 2 to 3 msec of the complex wave. 9 refs., 7 figs., 1 tab.

  19. Significance of blast wave studies to propulsion.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.

    1971-01-01

    Brief survey of experimental methods currently used for the study of blast wave phenomena with emphasis on high rate exothermic processes. The experimental techniques have used such devices as divergent test sections in shock or detonation tubes, employment of proper test gases, as in marginal detonations, and a variety of explosion systems from finite source explosion apparatus to devices where virtually point explosions are obtained by local breakdown initiated by means of focused laser irradiation. Other methods used are detonation tubes where pressure waves are generated by accelerating flames or by exothermic reactions developed behind reflected shocks, as well as a variety of converging shock and implosion vessels.

  20. Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

    SciTech Connect

    Uhm, Z. Lucas; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-07-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  1. Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves Encountering a Density Bump or Void

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing

    2014-07-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  2. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper.

    PubMed

    Schmidt, Slawa; Engelke, Pascal; Piglosiewicz, Björn; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Groß, Petra

    2013-11-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling light on the nanoscale.

  3. Arbitrary Amplitude DIA and DA Solitary Waves in Adiabatic Dusty Plasmas

    SciTech Connect

    Mamun, A. A.; Jahan, N.; Shukla, P. K.

    2008-10-15

    The dust-ion-acoustic (DIA) as well as the dust-acoustic (DA) solitary waves (SWs) in an adiabatic dusty plasma are investigated by the pseudo-potential approach which is valid for arbitrary amplitude SWs. The role of the adiabaticity of electrons and ions in modifying the basic features (polarity, speed, amplitude and width) of arbitrary amplitude DIA and DA SWs are explicitly examined. It is found that the effects of the adiabaticity of electrons and ions significantly modify the basic features (polarity, speed, amplitude and width) of the DIA and DA SWs. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  4. Blast wave mitigation by liquid foam

    NASA Astrophysics Data System (ADS)

    Monloubou, Martin; Dollet, Benjamin; Saint-Jalmes, Arnaud; Cantat, Isabelle; Soft Matter Team

    2014-11-01

    Due to their high apparent viscosity, liquid foams are good systems to absorb energy. This property is for instance used in the military domain to mitigate blast waves or explosions [Britan, 2009; Del Prete, 2013]. However, the underlying dissipation mechanisms are still not well understood. We address this issue by resolving in space and time a shock wave impacting a foam sample. We use a shock tube to send a shock wave on a foam with controlled liquid fraction, bubble size and physico-chemistry. The impacting shock creates an expanding cavity in the foam and propagates through the whole sample. The dynamics is recorded with a high speed camera and pressure signals are simultaneously measured. We show the influence of the bubble size and of the shock amplitude on the velocity and on the attenuation of the pressure signal, and on the foam destruction rate. This work is supported by the DGA.

  5. Computation of viscous blast wave flowfields

    NASA Technical Reports Server (NTRS)

    Atwood, Christopher A.

    1991-01-01

    A method to determine unsteady solutions of the Navier-Stokes equations was developed and applied. The structural finite-volume, approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the interaction of blast-waves with stationary targets. The inviscid flux is evaluated using MacCormack's modified Steger-Warming flux or Roe flux difference splittings with total variation diminishing limiters, while the viscous flux is computed using central differences. The use of implicit boundary conditions in conjunction with a telescoping in time and space method permitted solutions to this strongly unsteady class of problems. Comparisons of numerical, analytical, and experimental results were made in two and three dimensions. These comparisons revealed accurate wave speed resolution with nonoscillatory discontinuity capturing. The purpose of this effort was to address the three-dimensional, viscous blast-wave problem. Test cases were undertaken to reveal these methods' weaknesses in three regimes: (1) viscous-dominated flow; (2) complex unsteady flow; and (3) three-dimensional flow. Comparisons of these computations to analytic and experimental results provided initial validation of the resultant code. Addition details on the numerical method and on the validation can be found in the appendix. Presently, the code is capable of single zone computations with selection of any permutation of solid wall or flow-through boundaries.

  6. Ray invariants, plane wave spectra, and adiabatic modes for tapered dielectric waveguides

    NASA Astrophysics Data System (ADS)

    Arnold, J. M.; Felsen, L. B.

    1984-10-01

    In nonseparable problems resulting from the analysis of wave propagation in longitudinally varying waveguides, such as a wedge-shaped taper, singularities appear in both ray and coupled mode treatments at the local normal mode cutoff transition. A uniformization of the local normal (adiabatic) mode is proposed, using plane wave spectra, which effectively resolves this difficulty.

  7. Non-equilibrium ionized blast wave

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1974-01-01

    The structure of a cylindrical blast wave with ionization at non-LTE conditions was calculated using equations previously developed by Wu and Fu (1970). The degree of ionization was predicted by a modified Saha equation. Temperature profiles show that the temperature at non-LTE conditions is lower than at LTE near the shock front. This corresponds to a higher degree of ionization for the non-LTE limit, which indicates that the neutral gas absorption is much more efficient at non-LTE than at the LTE limit. The decaying velocity under non-LTE is approximately 15% less than under LTE.

  8. On the Interaction and Coalescence if Spherical Blast Waves

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Freeman, Robert J.

    2005-01-01

    The scaling and similarity laws concerning the propagation of isolated spherical blast waves are briefly reviewed. Both point source explosions and high pressure gas explosions are considered. Test data on blast overpressure from the interaction and coalescence of spherical blast waves emanating from explosives in the form of shaped charges of different strength placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure. The results point out the possibility of detecting source explosions from far-field pressure measurements.

  9. Another self-similar blast wave: Early time asymptote with shock heated electrons and high thermal conductivity

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Edgar, R. J.

    1982-01-01

    Accurate approximations are presented for the self-similar structures of nonradiating blast waves with adiabatic ions, isothermal electrons, and equation ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform density case) and have negligible external pressure. The results provide the early time asymptote for systems with shock heating of electrons and strong thermal conduction. In addition, they provide analytical results against which two fluid numerical hydrodynamic codes can be checked.

  10. Note: Device for underwater laboratory simulation of unconfined blast waves

    NASA Astrophysics Data System (ADS)

    Courtney, Elijah; Courtney, Amy; Courtney, Michael

    2015-06-01

    Shock tubes simulate blast waves to study their effects in air under laboratory conditions; however, few experimental models exist for simulating underwater blast waves that are needed for facilitating experiments in underwater blast transmission, determining injury thresholds in marine animals, validating numerical models, and exploring mitigation strategies for explosive well removals. This method incorporates an oxy-acetylene driven underwater blast simulator which creates peak blast pressures of about 1860 kPa. Shot-to-shot consistency was fair, with an average standard deviation near 150 kPa. Results suggest that peak blast pressures from 460 kPa to 1860 kPa are available by adjusting the distance from the source.

  11. Note: Device for underwater laboratory simulation of unconfined blast waves.

    PubMed

    Courtney, Elijah; Courtney, Amy; Courtney, Michael

    2015-06-01

    Shock tubes simulate blast waves to study their effects in air under laboratory conditions; however, few experimental models exist for simulating underwater blast waves that are needed for facilitating experiments in underwater blast transmission, determining injury thresholds in marine animals, validating numerical models, and exploring mitigation strategies for explosive well removals. This method incorporates an oxy-acetylene driven underwater blast simulator which creates peak blast pressures of about 1860 kPa. Shot-to-shot consistency was fair, with an average standard deviation near 150 kPa. Results suggest that peak blast pressures from 460 kPa to 1860 kPa are available by adjusting the distance from the source. PMID:26133878

  12. Reactive Blast Waves from Composite Charges

    SciTech Connect

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-10-16

    Investigated here is the performance of composite explosives - measured in terms of the blast wave they drive into the surrounding environment. The composite charge configuration studied here was a spherical booster (1/3 charge mass), surrounded by aluminum (Al) powder (2/3 charge mass) at an initial density of {rho}{sub 0} = 0.604 g/cc. The Al powder acts as a fuel but does not detonate - thereby providing an extreme example of a 'non-ideal' explosive (where 2/3 of the charge does not detonate). Detonation of the booster charge creates a blast wave that disperses the Al powder and ignites the ensuing Al-air mixture - thereby forming a two-phase combustion cloud embedded in the explosion. Afterburning of the booster detonation products with air also enhances and promotes the Al-air combustion process. Pressure waves from such reactive blast waves have been measured in bomb calorimeter experiments. Here we describe numerical simulations of those experiments. A Heterogeneous Continuum Model was used to model the dispersion and combustion of the Al particle cloud. It combines the gasdynamic conservation laws for the gas phase with a dilute continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models of Khasainov. It incorporates a combustion model based on mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Adaptive Mesh Refinement (AMR) was used to capture the energy-bearing scales of the turbulent flow on the computational grid, and to track

  13. Percolation of Blast Waves though Sand

    NASA Astrophysics Data System (ADS)

    Proud, William

    2013-06-01

    Previous research has concentrated on the physical processes occurring when samples of sand, of varying moisture content, were shock compressed. In this study quartz sand samples are subjected to blast waves over a range of pressure and duration. Aspects of particle movement are discussed; the global movement of a bed hundreds of particles thick is a fraction of particle width. The main diagnostics used are pressure sensors and high-speed photography. Results are presented for a range of particle sizes, aspect ratio, density and moisture content. While the velocity of the percolation through the bed is primarily controlled by density and porosity the effect of moisture reveals a more complex dependence. The ISP acknowledges the support of the Atomic Weapons Establishment and Imperial College London.

  14. Characterising the acceleration phase of blast wave formation

    SciTech Connect

    Fox, T. E. Pasley, J.; Robinson, A. P. L.; Schmitz, H.

    2014-10-15

    Intensely heated, localised regions in uniform fluids will rapidly expand and generate an outwardly propagating blast wave. The Sedov-Taylor self-similar solution for such blast waves has long been studied and applied to a variety of scenarios. A characteristic time for their formation has also long been identified using dimensional analysis, which by its very nature, can offer several interpretations. We propose that, rather than simply being a characteristic time, it may be interpreted as the definitive time taken for a blast wave resulting from an intense explosion in a uniform media to contain its maximum kinetic energy. A scaling relation for this measure of the acceleration phase, preceding the establishment of the blast wave, is presented and confirmed using a 1D planar hydrodynamic model.

  15. Close-in Blast Waves from Spherical Charges*

    NASA Astrophysics Data System (ADS)

    Howard, William; Kuhl, Allen

    2011-06-01

    We study the close-in blast waves created by the detonation of spherical high explosives (HE) charges, via numerical simulations with our Arbitrary-Lagrange-Eulerian (ALE3D) code. We used a finely-resolved, fixed Eulerian 2-D mesh (200 μm per cell) to capture the detonation of the charge, the blast wave propagation in air, and the reflection of the blast wave from an ideal surface. The thermodynamic properties of the detonation products and air were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. The results were analyzed to evaluate the: (i) free air pressure-range curves: Δps (R) , (ii) free air impulse curves, (iii) reflected pressure-range curves, and (iv) reflected impulse-range curves. A variety of explosives were studied. Conclusions are: (i) close-in (R < 10 cm /g 1 / 3) , each explosive had its own (unique) blast wave (e.g., Δps (R , HE) ~ a /Rn , where n is different for each explosive); (ii) these close-in blast waves do not scale with the ``Heat of Detonation'' of the explosive (because close-in, there is not enough time to fully couple the chemical energy to the air via piston work); (iii) instead they are related to the detonation conditions inside the charge. Scaling laws will be proposed for such close-in blast waves.

  16. Shortcut to adiabaticity in full-wave optics for ultra-compact waveguide junctions

    NASA Astrophysics Data System (ADS)

    Della Valle, Giuseppe; Perozziello, Gerardo; Longhi, Stefano

    2016-09-01

    We extend the concept of shortcuts to adiabaticity to full-wave optics and provide an application to the design of an ultra-compact waveguide junction. In particular, we introduce a procedure allowing one to synthesize a purely dielectric optical potential that precisely compensates for non-adiabatic losses of the transverse electric fundamental mode in any (sufficiently regular) two-dimensional waveguide junction. Our results are corroborated by finite-element method numerical simulations in a Pöschl–Teller waveguide mode expander.

  17. The adiabatic limit of the exact factorization of the electron-nuclear wave function.

    PubMed

    Eich, F G; Agostini, Federica

    2016-08-01

    We propose a procedure to analyze the relation between the exact factorization of the electron-nuclear wave function and the Born-Oppenheimer approximation. We define the adiabatic limit as the limit of infinite nuclear mass. To this end, we introduce a unit system that singles out the dependence on the electron-nuclear mass ratio of each term appearing in the equations of the exact factorization. We observe how non-adiabatic effects induced by the coupling to the nuclear motion affect electronic properties and we analyze the leading term, connecting it to the classical nuclear momentum. Its dependence on the mass ratio is tested numerically on a model of proton-coupled electron transfer in different non-adiabatic regimes. PMID:27497542

  18. The adiabatic limit of the exact factorization of the electron-nuclear wave function

    NASA Astrophysics Data System (ADS)

    Eich, F. G.; Agostini, Federica

    2016-08-01

    We propose a procedure to analyze the relation between the exact factorization of the electron-nuclear wave function and the Born-Oppenheimer approximation. We define the adiabatic limit as the limit of infinite nuclear mass. To this end, we introduce a unit system that singles out the dependence on the electron-nuclear mass ratio of each term appearing in the equations of the exact factorization. We observe how non-adiabatic effects induced by the coupling to the nuclear motion affect electronic properties and we analyze the leading term, connecting it to the classical nuclear momentum. Its dependence on the mass ratio is tested numerically on a model of proton-coupled electron transfer in different non-adiabatic regimes.

  19. Adiabatic cooling of atoms by an intense standing wave

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Story, J. G.; Tollett, J. J.; Hulet, Randall G.

    1992-08-01

    Lithium atoms channeled in the nodes of an intense standing-wave radiation field are cooled to near the recoil limit by adibatically reducing the radiation intensity. The final momentum distribution has a narrow component with a root-mean-squared momentum of 2ħk in one dimension, where ħk is the momentum of a radiation-field photon. The data are compared with the results of a Monte Carlo simulation using a two-level atom model. This process may be useful for cooling and increasing the phase-space density of atoms confined in a magnetic trap.

  20. Heavy-Ion-Acoustic Solitary and Shock Waves in an Adiabatic Multi-Ion Plasma

    NASA Astrophysics Data System (ADS)

    Hossen, M. A.; Rahman, M. M.; Hossen, M. R.; Mamun, A. A.

    2015-08-01

    The standard reductive perturbation method has been employed to derive the Korteweg-deVries (K-dV) and Burgers (BG) equations to investigate the basic properties of heavy-ion-acoustic (HIA) waves in a plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The HIA solitary and shock structures are found to exist with either positive or negative potential. It is found that the effects of adiabaticity of inertial heavy ions, nonthermality of electrons, and number densities of plasma components significantly modify the basic properties of the HIA solitary and shock waves. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments.

  1. Measurement of Blast Waves from Bursting Pressureized Frangible Spheres

    NASA Technical Reports Server (NTRS)

    Esparza, E. D.; Baker, W. E.

    1977-01-01

    Small-scale experiments were conducted to obtain data on incident overpressure at various distances from bursting pressurized spheres. Complete time histories of blast overpressure generated by rupturing glass spheres under high internal pressure were obtained using eight side-on pressure transducers. A scaling law is presented, and its nondimensional parameters are used to compare peak overpressures, arrival times, impulses, and durations for different initial conditions and sizes of blast source. The nondimensional data are also compared, whenever possible, with results of theoretical calculations and compiled data for Pentolite high explosive. The scaled data are repeatable and show significant differences from blast waves generated by condensed high-explosives.

  2. Micro-blast waves using detonation transmission tubing

    NASA Astrophysics Data System (ADS)

    Samuelraj, I. Obed; Jagadeesh, G.; Kontis, K.

    2013-07-01

    Micro-blast waves emerging from the open end of a detonation transmission tube were experimentally visualized in this study. A commercially available detonation transmission tube was used (Nonel tube, M/s Dyno Nobel, Sweden), which is a small diameter tube coated with a thin layer of explosive mixture (HMX + traces of Al) on its inner side. The typical explosive loading for this tube is of the order of 18 mg/m of tube length. The blast wave was visualized using a high speed digital camera (frame rate 1 MHz) to acquire time-resolved schlieren images of the resulting flow field. The visualization studies were complemented by computational fluid dynamic simulations. An analysis of the schlieren images showed that although the blast wave appears to be spherical, it propagates faster along the tube axis than along a direction perpendicular to the tube axis. Additionally, CFD analysis revealed the presence of a barrel shock and Mach disc, showing structures that are typical of an underexpanded jet. A theory in use for centered large-scale explosions of intermediate strength (10 < Δ {p}/{p}_0 ≲ 0.02) gave good agreement with the blast trajectory along the tube axis. The energy of these micro-blast waves was found to be 1.25 ± 0.94 J and the average TNT equivalent was found to be 0.3. The repeatability in generating these micro-blast waves using the Nonel tube was very good (± 2 %) and this opens up the possibility of using this device for studying some of the phenomena associated with muzzle blasts in the near future.

  3. Rapid miniature fiber optic pressure sensors for blast wave measurements

    NASA Astrophysics Data System (ADS)

    Zou, Xiaotian; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

    2013-02-01

    Traumatic brain injury (TBI) is a serious potential threat to soldiers who are exposed to explosions. Since the pathophysiology of TBI associated with a blast wave is not clearly defined, it is crucial to have a sensing system to accurately quantify the blast wave dynamics. This paper presents an ultra-fast fiber optic pressure sensor based on Fabry-Perot (FP) interferometric principle that is capable of measuring the rapid pressure changes in a blast event. The blast event in the experiment was generated by a starter pistol blank firing at close range, which produced a more realistic wave profile compared to using compressed air driven shock tubes. To the authors' knowledge, it is also the first study to utilize fiber optic pressure sensors to measure the ballistics shock wave of a pistol firing. The results illustrated that the fiber optic pressure sensor has a rise time of 200 ns which demonstrated that the sensor has ability to capture the dynamic pressure transient during a blast event. Moreover, the resonant frequency of the sensor was determined to be 4.11 MHz, which agrees well with the specific designed value.

  4. Stress Wave Interaction Between Two Adjacent Blast Holes

    NASA Astrophysics Data System (ADS)

    Yi, Changping; Johansson, Daniel; Nyberg, Ulf; Beyglou, Ali

    2016-05-01

    Rock fragmentation by blasting is determined by the level and state of stress in the rock mass subjected to blasting. With the application of electronic detonators, some researchers stated that it is possible to achieve improved fragmentation through stress wave superposition with very short delay times. This hypothesis was studied through theoretical analysis in the paper. First, the stress in rock mass induced by a single-hole shot was analyzed with the assumptions of infinite velocity of detonation and infinite charge length. Based on the stress analysis of a single-hole shot, the stress history and tensile stress distribution between two adjacent holes were presented for cases of simultaneous initiation and 1 ms delayed initiation via stress superposition. The results indicated that the stress wave interaction is local around the collision point. Then, the tensile stress distribution at the extended line of two adjacent blast holes was analyzed for a case of 2 ms delay. The analytical results showed that the tensile stress on the extended line increases due to the stress wave superposition under the assumption that the influence of neighboring blast hole on the stress wave propagation can be neglected. However, the numerical results indicated that this assumption is unreasonable and yields contrary results. The feasibility of improving fragmentation via stress wave interaction with precise initiation was also discussed. The analysis in this paper does not support that the interaction of stress waves improves the fragmentation.

  5. Blast waves produced by interactions of femtosecond laser pulses with water.

    PubMed

    Li, Y T; Zhang, J; Teng, H; Li, K; Peng, X Y; Jin, Z; Lu, X; Zheng, Z Y; Yu, Q Z

    2003-05-01

    The behaviors of the blast waves produced by femtosecond laser-water interactions, and the blast waves induced by laser self-focusing in air, have been investigated using optical shadowgraphy at a maximum intensity of 1 x 10(16) W/cm(2). The temporal evolution of the blast wave launched by the water plasma can be described by a planar blast wave model including source mass. An aneurismlike structure, due to the quick propagation inside a hollow channel formed by laser self-focusing, is observed. The expansion of the channel in air is found to agree with a cylindrical self-similar blast wave solution. PMID:12786283

  6. Explosively-Driven Blast Waves in Small-Diameter Tubes

    NASA Astrophysics Data System (ADS)

    Cooper, M. A.; Marinis, R. T.; Oliver, M. S.

    Studies on blast waves are motivated by the need to understand dynamic pressure loadings in accident scenarios associated with rapid energy release in confined geometries. Explosions from fuel-air mixtures, explosives and industrial accidents often occur within a range of length scales associated with ducts, pipes, corridors, and tunnels [1, 2].

  7. Testing the blast wave model with Swift GRBs

    NASA Astrophysics Data System (ADS)

    Curran, P. A.; Starling, R. L. C.; van der Horst, A. J.; Wijers, R. A. M. J.; de Pasquale, M.; Page, M.

    2011-04-01

    The complex structure of the light curves of Swift GRBs (e.g. superimposed flares and shallow decay) has made their interpretation and that of the blast wave caused by the burst, more difficult than in the pre-Swift era. We aim to constrain the blast wave parameters: electron energy distribution, p, density profile of the circumburst medium, k, and the continued energy injection index, q. We do so by comparing the observed multi-wavelength light curves and X-ray spectra of a Swift sample to the predictions of the blast wave model.We can successfully interpret all of the bursts in our multi-wavelength sample of 10, except two, within the framework of the blast wave model, and we can estimate with confidence the electron energy distribution index for 6 of the sample. Furthermore we identify jet breaks in almost half of the bursts. The values of k suggest that the circumburst density profiles are not drawn from only one of the constant density or wind-like media populations. A statistical analysis of the distribution of p reveals that, even in the most conservative case of least scatter, the values are not consistent with a single, universal value. This is in agreement with our results for a larger sample of X-ray only afterglows which we summarise here.

  8. A systematic exposition of the conservation equations for blast waves.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Lundstrom, E. A.; Kuhl, A. L.; Kamel, M. M.

    1971-01-01

    In order to provide a rational background for the analysis of experimental observations of blast wave phenomena, the conservation equations governing their nonsteady flow field are formulated in a general manner, without the usual restrictions imposed by an equation of state, and with proper account taken, by means of source terms, of other effects which, besides the inertial terms that conventionally dominate these equations, can affect the flow. Taking advantage of the fact that a blast wave can be generally considered as a spatially one-dimensional flow field whose nonsteady behavior can be regarded, consequently, as a function of just two independent variables, two generalized blast wave coordinates are introduced, one associated with the front of the blast wave and the other with its flow field. The conservation equations are accordingly transformed into this coordinate system, acquiring thereby a comprehensive character, in that they refer then to any frame of reference, being applicable, in particular, to problems involving either space or time profiles of the gas-dynamic parameters in the Eulerian system, or time profiles in the Lagrangian system.

  9. Simulation of blast-induced, early-time intracranial wave physics leading to traumatic brain injury.

    SciTech Connect

    Taylor, Paul Allen; Ford, Corey C.

    2008-04-01

    U.S. soldiers are surviving blast and impacts due to effective body armor, trauma evacuation and care. Blast injuries are the leading cause of traumatic brain injury (TBI) in military personnel returning from combat. Understanding of Primary Blast Injury may be needed to develop better means of blast mitigation strategies. The objective of this paper is to investigate the effects of blast direction and strength on the resulting mechanical stress and wave energy distributions generated in the brain.

  10. Relationship between orientation to a blast and pressure wave propagation inside the rat brain.

    PubMed

    Chavko, Mikulas; Watanabe, Tomas; Adeeb, Saleena; Lankasky, Jason; Ahlers, Stephen T; McCarron, Richard M

    2011-01-30

    Exposure to a blast wave generated during an explosion may result in brain damage and related neurological impairments. Several mechanisms by which the primary blast wave can damage the brain have been proposed, including: (1) a direct effect of the shock wave on the brain causing tissue damage by skull flexure and propagation of stress and shear forces; and (2) an indirect transfer of kinetic energy from the blast, through large blood vessels and cerebrospinal fluid (CSF), to the central nervous system. To address a basic question related to the mechanisms of blast brain injury, pressure was measured inside the brains of rats exposed to a low level of blast (~35kPa), while positioned in three different orientations with respect to the primary blast wave; head facing blast, right side exposed to blast and head facing away from blast. Data show different patterns and durations of the pressure traces inside the brain, depending on the rat orientation to blast. Frontal exposures (head facing blast) resulted in pressure traces of higher amplitude and longer duration, suggesting direct transmission and reflection of the pressure inside the brain (dynamic pressure transfer). The pattern of the pressure wave inside the brain in the head facing away from blast exposures assumes contribution of the static pressure, similar to hydrodynamic pressure to the pressure wave inside the brain. PMID:21129403

  11. Blast Wave Driven Instabilities In Laboratory Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn; Drake, R.; Grosskopf, M.; Robey, H.; Hansen, J.; Miles, A.; Knauer, J.; Arnett, D.; Plewa, T.; Hearn, N.; Meakin, C.

    2008-05-01

    This presentation discusses experiments well scaled to the blast wave driven instabilities at the He/H interface during the explosion phase of SN1987A. This core-collapse supernova was detected about 50 kpc from Earth making it the first supernova observed so closely to earth in modern times. The progenitor star was a blue supergiant with a mass of 18-20 solar masses. A blast wave occurred following the supernova explosion because there was a sudden, finite release of energy. Blast waves consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 µm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses a three-dimensional interface with a wavelength of 71 µm in two orthogonal directions. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability. We have detected the interface structure under these conditions, using dual orthogonal radiography, and will show some of the resulting data. Recent advancements in our x-ray backlighting techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed. Current simulations do not show this phenomenon. This presentation will discuss the amount of mass in these spike extensions. Recent results from an experiment using more realistic initial conditions based on stellar evolution models will also be shown. This research was sponsored by the Stewardship Science Academic Alliance through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064.

  12. Review of methods to attenuate shock/blast waves

    NASA Astrophysics Data System (ADS)

    Igra, O.; Falcovitz, J.; Houas, L.; Jourdan, G.

    2013-04-01

    Quick and reliable shock wave attenuation is the goal of every protection facility and therefore it is not surprising that achieving this has drawn much attention during the past hundred years. Different options have been suggested; their usefulness varying from a reasonable protection to the opposite, a shock enhancement. An example for a suggestion for shock mitigation that turned out to be an enhancement of the impinging shock wave was the idea to cover a protected object with a foam layer. While the pressure behind the reflected shock wave from the foam frontal surface was smaller than that recorded in a similar reflection from a rigid wall [25], the pressure on the “protected” surface, attached to the foam's rear-surface, was significantly higher than that recorded in a similar reflection from a bare, rigid wall [11]. In protecting humans and installations from destructive shock and/or blast waves the prime goal is to reduce the wave amplitude and the rate of pressure increase across the wave front. Both measures result in reducing the wave harmful effects. During the past six decades several approaches for achieving the desired protection have been offered in the open literature. We point out in this review that while some of the suggestions offered are practical, others are impractical. In our discussion we focus on recent schemes for shock/blast wave attenuation, characterized by the availability of reliable measurements (notably pressure and optical diagnostics) as well as high-resolution numerical simulations.

  13. RESONANT AMPLIFICATION OF TURBULENCE BY THE BLAST WAVES

    SciTech Connect

    Zankovich, A. M.; Kovalenko, I. G.

    2015-02-10

    We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20, with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ∼ 1), meso- (l ∼ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, Δl < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ≈ 18) are surprisingly close to the observed scales (l ≈ 15) of ripples in the shell's surface of SNR 0509-67.5.

  14. Resonant Amplification of Turbulence by the Blast Waves

    NASA Astrophysics Data System (ADS)

    Zankovich, A. M.; Kovalenko, I. G.

    2015-02-01

    We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20, with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ~ 1), meso- (l ~ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, Δl < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ≈ 18) are surprisingly close to the observed scales (l ≈ 15) of ripples in the shell's surface of SNR 0509-67.5.

  15. Impact of complex blast waves on the human head: a computational study.

    PubMed

    Tan, Long Bin; Chew, Fatt Siong; Tse, Kwong Ming; Chye Tan, Vincent Beng; Lee, Heow Pueh

    2014-12-01

    Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head-helmet model for blast impact analyses in Abaqus(TM) (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330 kPa is registered at the parietal lobe which exceeds the 235 kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at

  16. Study of high Mach number laser driven blast waves in gases

    SciTech Connect

    Edens, A. D.; Adams, R. G.; Rambo, P.; Ruggles, L.; Smith, I. C.; Porter, J. L.; Ditmire, T.

    2010-11-15

    A series of experiments were performed examining the evolution of blast waves produced by laser irradiation of a target immersed in gas. Blast waves were produced by illumination of wires by 1 kJ, 1 ns laser pulses from the Z-Beamlet laser at Sandia National Laboratories. The blast waves were imaged by probe laser pulses at various times to examine the trajectory, radiative precursor, and induced perturbations on the blast wave front. Well defined perturbations were induced on the blast wave front with arrays of wires placed in the gas and the results of the experiments are compared to the theoretical predictions for the Vishniac overstability. It is found that the experimental results are in general agreement with these theoretical predictions on thin blast wave shells and are in quantitative agreement in the simplest case.

  17. Vorticity deposition, structure generation and the approach to self-similarity in colliding blast wave experiments

    NASA Astrophysics Data System (ADS)

    Robinson, A. P. L.; Schmitz, H.; Fox, T. E.; Pasley, J.; Symes, D. R.

    2015-03-01

    When strong shocks interact with transverse density gradients, it is well known that vorticity deposition occurs. When two non-planar blast waves interact, a strong shock will propagate through the internal structure of each blast wave where the shock encounters such density gradients. There is therefore the potential for the resulting vorticity to produce pronounced density structures long after the passage of these shocks. If the two blast waves have evolved to the self-similar (Sedov) phase this is not a likely prospect, but for blast waves at a relatively early stage of their evolution this remains possible. We show, using 2D numerical simulations, that the interactions of two 'marginally young' blast waves can lead to strong vorticity deposition which leads to the generation of a strong protrusion and vortex ring as mass is driven into the internal structure of the weaker blast wave.

  18. A thoracic mechanism of mild traumatic brain injury due to blast pressure waves.

    PubMed

    Courtney, A C; Courtney, M W

    2009-01-01

    The mechanisms by which blast pressure waves cause mild-to-moderate traumatic brain injury (mTBI) are an open question. Possibilities include acceleration of the head, direct passage of the blast wave via the cranium, and propagation of the blast wave to the brain via a thoracic mechanism. The hypothesis that the blast pressure wave reaches the brain via a thoracic mechanism is considered in light of ballistic and blast pressure wave research. Ballistic pressure waves, caused by penetrating ballistic projectiles or ballistic impacts to body armor, can only reach the brain via an internal mechanism and have been shown to cause cerebral effects. Similar effects have been documented when a blast pressure wave has been applied to the whole body or focused on the thorax in animal models. While vagotomy reduces apnea and bradycardia due to ballistic or blast pressure waves, it does not eliminate neural damage in the brain, suggesting that the pressure wave directly affects the brain cells via a thoracic mechanism. An experiment is proposed which isolates the thoracic mechanism from cranial mechanisms of mTBI due to blast wave exposure. Results have implications for evaluating risk of mTBI due to blast exposure and for developing effective protection. PMID:18829180

  19. Measurement of the decay rate of single-frequency perturbations on blast waves.

    PubMed

    Edens, A D; Ditmire, T; Hansen, J F; Edwards, M J; Adams, R G; Rambo, P K; Ruggles, L; Smith, I C; Porter, J L

    2005-12-01

    To explore the validity of theories forwarded to explain the dynamics of hydrodynamic perturbations on high Mach number blast waves, we have studied the decay rate of perturbations on blast waves traveling through nitrogen gas. In our experiments, 1 kJ pulses from the Z-Beamlet laser at Sandia National Laboratories illuminated solid targets immersed in gas and created blast waves. The polytropic index implied by comparing experiment to theoretical predictions is compared to simulation results. PMID:16384385

  20. Simulation of the Reflected Blast Wave froma C-4 Charge

    SciTech Connect

    Howard, W M; Kuhl, A L; Tringe, J W

    2011-08-01

    The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 {micro}m per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 8 ranges (GR = 0, 2, 4, 8, 10, and 12 inches) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 2 inches), which were dominated by jetting effects.

  1. Towards a fast-running method for blast-wave mitigation by a prismatic blast wall

    NASA Astrophysics Data System (ADS)

    Éveillard, Sébastien; Lardjane, Nicolas; Vinçont, Jean-Yves; Sochet, Isabelle

    A procedure aimed at developing a fast-running method for blast-wave effects characterization behind a protection barrier is presented. Small-scale experiments of a hemispherical gaseous charge (stoichiometric propane-oxygen mixture) without and with a prismatic protective barrier are used to validate the use of an in-house CFD code for gaseous detonation. From numerical experiments, pressure loss of a blast wave at a corner is quantified. These fits, in conjunction with TM5-1300 reflection charts, are used to estimate the maximum overpressure around a protective barrier through geometrical and empirical laws. The results show good agreement with numerical and experimental data from the ANR-BARPPRO research project.

  2. Self-similar relativistic blast waves with energy injection

    NASA Astrophysics Data System (ADS)

    van Eerten, Hendrik

    2014-08-01

    A sufficiently powerful astrophysical source with power-law luminosity in time will give rise to a self-similar relativistic blast wave with a reverse shock travelling into the ejecta and a forward shock moving into the surrounding medium. Once energy injection ceases and the last energy is delivered to the shock front, the blast wave will transit into another self-similar stage depending only on the total amount of energy injected. I describe the effect of limited duration energy injection into environments with density depending on radius as a power law, emphasizing optical/X-ray Gamma-ray Burst afterglows as applications. The blast wave during injection is treated analytically, the transition following last energy injection with one-dimensional simulations. Flux equations for synchrotron emission from the forward and reverse shock regions are provided. The reverse shock emission can easily dominate, especially with different magnetizations for both regions. Reverse shock emission is shown to support both the reported X-ray and optical correlations between afterglow plateau duration and end time flux, independently of the luminosity power-law slope. The model is demonstrated by application to bursts 120521A and 090515, and can accommodate their steep post-plateau light-curve slopes.

  3. The effects of reverberant blast waves on the auditory system.

    PubMed

    Ahroon, W A; Hamernik, R P; Lei, S F

    1996-10-01

    Chinchillas were exposed to 1, 10, or 100 reverberant impulses at 150, 155, or 160 dB peak SPL. The impulses were generated by one of two different shock tubes, each producing blast waves having a different spectral composition, with one emphasizing low frequencies (< 0.5 kHz) and the other midfrequencies (2-4 kHz). Impulses were presented at the rate of one per minute. This parametric paradigm yielded 18 exposure conditions with 15 animals/condition. Hearing thresholds were measured using auditory-evoked potentials and the sensory epithelium was evaluated with the surface preparation. In general, trauma increased as the total energy of the exposure, determined by the peak SPL and number of presentations, increased. The dependent variables (permanent threshold shift and sensory cell loss) varied in an orderly fashion across frequency as the peak and number of presentations were increased for both blast wave sources. There were, however, consistent differences between the effects of the low- and high-frequency energy "content" blast waves. Correlations between the dependent variables and the energy of exposure were highest for P- or A-weighted energies [Patterson et al., J. Acoust. Soc. Am. 93, 2860-2869 (1993)]. PMID:8865633

  4. Interactions between Blast Waves and V-Shaped and Cone-Shaped Structures

    NASA Astrophysics Data System (ADS)

    Peng, W.; Zhang, Z. Y.; Gogos, G.; Gazonas, G.

    2011-09-01

    A 2-D numerical model of interactions between a blast wave and a V-shaped or a cone-shaped structure is developed. The model simulates the blast wave reflection from a V-shaped or a cone-shaped structure, the movement of the structure due to the blast impact and the induced shock wave behind the structure. Elliptic grid generation and coordinate transformation are utilized to solve the flow fields in the irregular physical domain. Different types of blast wave reflections, such as normal reflection, oblique reflection and Mach stem reflection, are captured by the numerical model. It is found that the reflected pressure and impulse transmitted to the structure decrease with the increase of incident angle. On the other hand, with the increase of incident angle, the effects of fluid structure interactions (FSI) in reducing the blast loads decreases. The FSI coupled with oblique or Mach stem reflection improves the blast wave mitigation.

  5. Relationship among shock-wave velocity, particle velocity, and adiabatic exponent for dry air

    NASA Astrophysics Data System (ADS)

    Kim, In H.; Hong, Sang H.; Jhung, Kyu S.; Oh, Ki-Hwan; Yoon, Yo K.

    1991-07-01

    Using the results of the detailed numerical calculations, it is shown that the relationship between the shock-wave velocity U sub s and the particle velocity U sub p for shock-compressed dry air can be represented accurately by the linear relation U sub s = a(P0) + b(P0)U sub p in a wide range of U sub p (U sub p = 2 to 9 ) km/s and initial pressure P0 = 10 to the -6th to 1 atm, where a and b are given by the cubic polynomials of log10P0. Based on the linear U sub s - U sub p relation, an analytic expression has been obtained for the adiabatic exponent gamma as a function of particle velocity.

  6. Filtering of matter-wave vibrational states via spatial adiabatic passage

    SciTech Connect

    Loiko, Yu.; Ahufinger, V.; Corbalan, R.; Mompart, J.; Birkl, G.

    2011-03-15

    We discuss the filtering of the vibrational states of a cold atom in an optical trap by chaining this trap with two empty ones and adiabatically controlling the tunneling. Matter-wave filtering is performed by selectively transferring the population of the highest populated vibrational state to the most distant trap while the population of the rest of the states remains in the initial trap. Analytical conditions for two-state filtering are derived and then applied to an arbitrary number of populated bound states. Realistic numerical simulations close to state-of-the-art experimental arrangements are performed by modeling the triple well with time-dependent Poeschl-Teller potentials. In addition to filtering of vibrational states, we discuss applications for quantum tomography of the initial population distribution and engineering of atomic Fock states that, eventually, could be used for tunneling-assisted evaporative cooling.

  7. Investigation of blast wave characteristics for layered thermobaric charges

    NASA Astrophysics Data System (ADS)

    Trzciński, W. A.; Barcz, K.

    2012-03-01

    The explosion of an annular charge composed of a hexogen core and a layer consisting of a mixture of ammonium nitrate and aluminum particles was studied. X-ray photography was used to trace the curvature of the shock wave in the external layer. The pressure blast characteristics and the light output of the explosion cloud were investigated using bunkers of different sizes and varying levels of the opening (the ratio of the hole surface to the total bunker surface). Overpressure peaks, the impulses of incident waves, and the impulses determined for the specified time duration were analyzed.

  8. Dynamic Modelling of Fault Slip Induced by Stress Waves due to Stope Production Blasts

    NASA Astrophysics Data System (ADS)

    Sainoki, Atsushi; Mitri, Hani S.

    2016-01-01

    Seismic events can take place due to the interaction of stress waves induced by stope production blasts with faults located in close proximity to stopes. The occurrence of such seismic events needs to be controlled to ensure the safety of the mine operators and the underground mine workings. This paper presents the results of a dynamic numerical modelling study of fault slip induced by stress waves resulting from stope production blasts. First, the calibration of a numerical model having a single blast hole is performed using a charge weight scaling law to determine blast pressure and damping coefficient of the rockmass. Subsequently, a numerical model of a typical Canadian metal mine encompassing a fault parallel to a tabular ore deposit is constructed, and the simulation of stope extraction sequence is carried out with static analyses until the fault exhibits slip burst conditions. At that point, the dynamic analysis begins by applying the calibrated blast pressure to the stope wall in the form of velocities generated by the blast holes. It is shown from the results obtained from the dynamic analysis that the stress waves reflected on the fault create a drop of normal stresses acting on the fault, which produces a reduction in shear stresses while resulting in fault slip. The influence of blast sequences on the behaviour of the fault is also examined assuming several types of blast sequences. Comparison of the blast sequence simulation results indicates that performing simultaneous blasts symmetrically induces the same level of seismic events as separate blasts, although seismic energy is more rapidly released when blasts are performed symmetrically. On the other hand when nine blast holes are blasted simultaneously, a large seismic event is induced, compared to the other two blasts. It is concluded that the separate blasts might be employed under the adopted geological conditions. The developed methodology and procedure to arrive at an ideal blast sequence can

  9. A parametric study of self-similar blast waves.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Kuhl, A. L.; Lundstrom, E. A.; Kamel, M. M.

    1972-01-01

    Comprehensive examination of self-similar blast waves with respect to two parameters, one describing the front velocity and the other the variation of the ambient density immediately ahead of the front. All possible front trajectories are taken into account, including limiting cases of the exponential and logarithmic form. The structure of the waves is analyzed by means of a phase plane defined in terms of two reduced coordinates. Loci of extrema of the integral curves in the phase plane are traced, and loci of singularities are determined on the basis of their intersections. Boundary conditons are introduced for the case where the medium into which the waves propagate is at rest. Representative solutions, pertaining to all the possible cases of blast waves bounded by shock fronts propagating into an atmosphere of uniform density, are obtained by evaluating the integral curves and determining the corresponding profiles of the gasdynamic parameters. Particular examples of integral curves for waves bounded by detonations are given, and all the degenerate solutions corresponding to cases where the integral curve is reduced to a point are delineated.

  10. Microscopic origin of self-similarity in granular blast waves

    NASA Astrophysics Data System (ADS)

    Barbier, M.; Villamaina, D.; Trizac, E.

    2016-08-01

    The self-similar expansion of a blast wave, well-studied in air, has peculiar counterparts in dense and dissipative media such as granular gases. Recent results have shown that, while the traditional Taylor-von Neumann-Sedov (TvNS) derivation is not applicable to such granular blasts, they can nevertheless be well understood via a combination of microscopic and hydrodynamic insights. In this article, we provide a detailed analysis of these methods associating molecular dynamics simulations and continuum equations, which successfully predict hydrodynamic profiles, scaling properties, and the instability of the self-similar solution. We also present new results for the energy conserving case, including the particle-level analysis of the classic TvNS solution and its breakdown at higher densities.

  11. Cylindrically converging blast waves in air

    NASA Astrophysics Data System (ADS)

    Matsuo, H.; Nakamura, Y.

    1981-07-01

    Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.

  12. Model for small arms fire muzzle blast wave propagation in air

    NASA Astrophysics Data System (ADS)

    Aguilar, Juan R.; Desai, Sachi V.

    2011-11-01

    Accurate modeling of small firearms muzzle blast wave propagation in the far field is critical to predict sound pressure levels, impulse durations and rise times, as functions of propagation distance. Such a task being relevant to a number of military applications including the determination of human response to blast noise, gunfire detection and localization, and gun suppressor design. Herein, a time domain model to predict small arms fire muzzle blast wave propagation is introduced. The model implements a Friedlander wave with finite rise time which diverges spherically from the gun muzzle. Additionally, the effects in blast wave form of thermoviscous and molecular relaxational processes, which are associated with atmospheric absorption of sound were also incorporated in the model. Atmospheric absorption of blast waves is implemented using a time domain recursive formula obtained from numerical integration of corresponding differential equations using a Crank-Nicholson finite difference scheme. Theoretical predictions from our model were compared to previously recorded real world data of muzzle blast wave signatures obtained by shooting a set different sniper weapons of varying calibers. Recordings containing gunfire acoustical signatures were taken at distances between 100 and 600 meters from the gun muzzle. Results shows that predicted blast wave slope and exponential decay agrees well with measured data. Analysis also reveals the persistency of an oscillatory phenomenon after blast overpressure in the recorded wave forms.

  13. Computational study of human head response to primary blast waves of five levels from three directions.

    PubMed

    Wang, Chenzhi; Pahk, Jae Bum; Balaban, Carey D; Miller, Mark C; Wood, Adam R; Vipperman, Jeffrey S

    2014-01-01

    Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts. PMID:25409326

  14. Computational study of human head response to primary blast waves of five levels from three directions.

    PubMed

    Wang, Chenzhi; Pahk, Jae Bum; Balaban, Carey D; Miller, Mark C; Wood, Adam R; Vipperman, Jeffrey S

    2014-01-01

    Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.

  15. Computational Study of Human Head Response to Primary Blast Waves of Five Levels from Three Directions

    PubMed Central

    Wang, Chenzhi; Pahk, Jae Bum; Balaban, Carey D.; Miller, Mark C.; Wood, Adam R.; Vipperman, Jeffrey S.

    2014-01-01

    Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts. PMID:25409326

  16. Concerning isothermal self-similar blast waves. I - One-dimensional flow and its stability. II - Two-dimensional flow and its stability. [in stellar atmosphere

    NASA Technical Reports Server (NTRS)

    Lerche, I.

    1978-01-01

    One-dimensional self-similar isothermal flow behind a blast wave propagating in a medium whose density varies with distance is investigated for the cases of one-dimensional and two-dimensional flow. The isothermal flow model is adopted as an alternative to adiabatic models of self-similar flow, which neglect heat flux. The topology of the one-dimensional flow solutions, the singularities, and the influence of boundary conditions are discussed; the instability of the isothermal blast waves against nonself-similar perturbations is also considered. The number of critical points in the two-dimensional solutions is found to vary from the number in the one-dimensional problem.

  17. Numerical Study on Blast Wave Propagation Driven by Unsteady Ionization Plasma

    SciTech Connect

    Ogino, Yousuke; Sawada, Keisuke; Ohnishi, Naofumi

    2008-04-28

    Understanding the dynamics of laser-produced plasma is essential for increasing the available thrust and energy conversion efficiency from a pulsed laser to a blast wave in a gas-driven laser-propulsion system. The performance of a gas-driven laser-propulsion system depends heavily on the laser-driven blast wave dynamics as well as on the ionizing and/or recombining plasma state that sustains the blast wave. In this study, we therefore develop a numerical simulation code for a laser-driven blast wave coupled with time-dependent rate equations to explore the formation of unsteady ionizing plasma produced by laser irradiation. We will also examine the various properties of blast waves and unsteady ionizing plasma for different laser input energies.

  18. Reduction of optically observed artillery blast wave trajectories using low dimensionality models

    NASA Astrophysics Data System (ADS)

    Steward, Bryan J.; Gross, Kevin C.; Perram, Glen P.

    2011-05-01

    Muzzle blast trajectories from firings of a 152 mm caliber gun howitzer were obtained with high-speed optical imagers and used to assess the fidelity with which low dimensionality models can be used for data reduction. Characteristic flow regions were defined for the blast waves. The near-field region was estimated to extend to 0.98 - 1.25 meters from the muzzle and the far-field region was estimated to begin at 2.61 - 3.31 meters. Blast wave geometries and radial trajectories were collected in the near through far-fields with visible imagers operating at 1,600 Hz. Beyond the near-field the blast waves exhibited a near-spherical geometry in which the major axis of the blast lay along the axis of the gun barrel and measured within 95% of the minor axis. Several blast wave propagation models were applied to the mid and far-field data to determine their ability to reduce the blast wave trajectories to fewer parameters while retaining the ability to distinguish amongst three munitions configurations. A total of 147 firings were observed and used to assess within-configuration variability relative to separation between configurations. Results show that all models perform well, and drag and point blast model parameters additionally provide insight into phenomenology of the blast.

  19. Experiments on cylindrically converging blast waves in atmospheric air

    NASA Astrophysics Data System (ADS)

    Matsuo, Hideo; Nakamura, Yuichi

    1980-06-01

    Cylindrically converging blast waves have been produced in normal atmospheric conditions by the detonation of the explosives, pentaerythritoltetranitrate, (PETN), over cylindrical surfaces. The shocks generated in this way are so strong that the fronts propagating through the air become luminous of themselves. The production and the propagation of the shocks have been monitored with a framing camera and a streak camera, and the time-space relations of the shock propagations have been determined using an electrical ionization probing system. The results have shown that the trajectory of the shock fronts near the axis of the cylinder can be approximately represented by the Guderley's formula.

  20. Blast Wave Exposure Impairs Memory and Decreases Axon Initial Segment Length

    PubMed Central

    Baalman, Kelli L.; Cotton, R. James; Rasband, S. Neil

    2013-01-01

    Abstract Exposure to a blast wave has been proposed to cause mild traumatic brain injury (mTBI), with symptoms including altered cognition, memory, and behavior. This idea, however, remains controversial, and the mechanisms of blast-induced brain injury remain unknown. To begin to resolve these questions, we constructed a simple compressed air shock tube, placed rats inside the tube, and exposed them to a highly reproducible and controlled blast wave. Consistent with the generation of a mild injury, 2 weeks after exposure to the blast, we found that motor performance was unaffected, and a panel of common injury markers showed little or no significant changes in expression in the cortex, corpus callosum, or hippocampus. Similarly, we were unable to detect elevated spectrin breakdown products in brains collected from blast-exposed rats. Using an object recognition task, however, we found that rats exposed to a blast wave spent significantly less time exploring a novel object when compared with control rats. Intriguingly, we also observed a significant shortening of the axon initial segment (AIS) in both the cortex and hippocampus of blast-exposed rats, suggesting altered neuronal excitability after exposure to a blast. A computational model showed that shortening the AIS increased both threshold and the interspike interval of repetitively firing neurons. These results support the conclusion that exposure to a single blast wave can lead to mTBI with accompanying cognitive impairment and subcellular changes in the molecular organization of neurons. PMID:23025758

  1. Spike Penetration in Blast-Wave-Driven Instabilities

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul

    2010-05-01

    Recent experiments by C. Kuranz and collaborators, motivated by structure in supernovae, have studied systems in which planar blast waves encounter interfaces where the density decreases. During the Rayleigh-Taylor (RT) phase of such experiments, they observed greater penetration of the RT spikes than tends to be seen in simulations. Here we seek to employ semi-analytic theory to understand the general nature and regimes of spike penetration for blast-wave-driven instabilities. This problem is not trivial as one must account for the initial vorticity deposition at the interface, for its time-dependent deceleration, for the expansion of the shocked material in time and space, and for the drag on the broadened tips of the spikes. We offer here an improved evaluation of the material expansion in comparison to past work. The goal is to use such models to increase our ability to interpret the behavior of simulations of such systems, in both the laboratory and astrophysics. Supported by the US DOE NNSA under the Predictive Sci. Academic Alliance Program by grant DE-FC52-08NA28616, the Stewardship Sci. Academic Alliances program by grant DE-FG52-04NA00064, and the Nat. Laser User Facility by grant DE-FG03-00SF22021.

  2. Spike penetration in blast-wave-driven instabilities

    NASA Astrophysics Data System (ADS)

    Drake, R. P.

    2009-11-01

    Recent experiments by C. Kuranz and collaborators, motivated by structure in supernovae, have studied systems in which planar blast waves encounter interfaces where the density decreases. During the Rayleigh-Taylor (RT) phase of such experiments, they observed greater penetration of the RT spikes than tends to be seen in simulations. Here we seek to employ semi-analytic theory to understand the general nature and regimes of spike penetration for blast-wave-driven instabilities. This problem is not trivial as one must account for the initial vorticity deposition at the interface, for its time-dependent deceleration, for the expansion of the shocked material in time and space, and for the drag on the broadened tips of the spikes. One can hope that such models will increase our ability to interpret the behavior of simulations of such systems, in both the laboratory and astrophysics. Supported by the US DOE NNSA under the Predictive Sci. Academic Alliance Program by grant DE-FC52-08NA28616, the Stewardship Sci. Academic Alliances program by grant DE-FG52-04NA00064, and the Nat. Laser User Facility by grant DE-FG03--00SF22021.

  3. Molecular wave function and effective adiabatic potentials calculated by extended multi-configuration time-dependent Hartree-Fock method

    SciTech Connect

    Kato, Tsuyoshi; Ide, Yoshihiro; Yamanouchi, Kaoru

    2015-12-31

    We first calculate the ground-state molecular wave function of 1D model H{sub 2} molecule by solving the coupled equations of motion formulated in the extended multi-configuration time-dependent Hartree-Fock (MCTDHF) method by the imaginary time propagation. From the comparisons with the results obtained by the Born-Huang (BH) expansion method as well as with the exact wave function, we observe that the memory size required in the extended MCTDHF method is about two orders of magnitude smaller than in the BH expansion method to achieve the same accuracy for the total energy. Second, in order to provide a theoretical means to understand dynamical behavior of the wave function, we propose to define effective adiabatic potential functions and compare them with the conventional adiabatic electronic potentials, although the notion of the adiabatic potentials is not used in the extended MCTDHF approach. From the comparison, we conclude that by calculating the effective potentials we may be able to predict the energy differences among electronic states even for a time-dependent system, e.g., time-dependent excitation energies, which would be difficult to be estimated within the BH expansion approach.

  4. Chest wall velocity as a predictor of nonauditory blast injury in a complex wave environment.

    PubMed

    Axelsson, H; Yelverton, J T

    1996-03-01

    Previous blast injury prediction criteria have been based on exposure to classic Friedlander or ideal blast waves. An ideal waveform is characterized by an instantaneous rise to a peak overpressure that decays exponentially to ambient pressure followed by a negative phase. The prediction criteria did not address injuries resulting from exposure to complex blast waves. It was difficult to establish a simple relationship between the two because complex blast waves typically consist of multiple shocks with variable frequency content and intensity that may be superimposed on a slow rising quasistatic pressure pulse. This paper deals with the application of a single degree of freedom mathematical model, originally developed to measure the response of the thorax to Friedlander waves, to calculate chest wall velocities resulting from various complex blast loads. Experimental results with sheep, exposed to complex blast waves in enclosures, demonstrated that there was a good relationship between the Adjusted Severity of Injury Index (which includes injury to the lungs, upper respiratory tract, gastrointestinal tract and solid intraabdominal organs) and the calculated peak inward chest wall velocity. In addition, there was a good correlation between these results and previously established Friedlander injury prediction curves. The velocity of complex blast waves was nearly the same as that of Friedlander waves for a given degree of injury: 3-4.5 meters/second for threshold injury, 8-12 meters/second for an LD1, and 12-17 meters/second for an LD50. PMID:8606417

  5. DYNAMICS AND AFTERGLOW LIGHT CURVES OF GAMMA-RAY BURST BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    SciTech Connect

    Uhm, Z. Lucas; Zhang Bing; Hascoeet, Romain; Daigne, Frederic; Mochkovitch, Robert; Park, Il H.

    2012-12-20

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  6. Measurement of blast wave by a miniature fiber optic pressure transducer in the rat brain.

    PubMed

    Chavko, Mikulas; Koller, Wayne A; Prusaczyk, W Keith; McCarron, Richard M

    2007-01-30

    Exposure to blast wave that is generated during an explosion may result in brain damage and related neurological impairments. The aim of this study was to investigate pressure changes induced by exposure to blast inside the rat brain. For intracranial pressure measurement we used a miniature optic fiber sensor (o.d. 550 microm) with a computer recording system. The sensor was placed in the third cerebral ventricle of anesthetized rats exposed to 40 kPa blast wave in a pneumatic-pressure driven shock tube. Short pressure waves lasting several ms were detected inside the brain with the magnitude that might result in nervous tissue damage. PMID:16949675

  7. Radiative precursors driven by converging blast waves in noble gases

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s{sup −1} blast waves through gases of densities of the order 10{sup −5} g cm{sup −3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  8. Bubble merger model for the nonlinear Rayleigh-Taylor instability driven by a strong blast wave

    SciTech Connect

    Miles, A R

    2004-03-18

    A bubble merger model is presented for the nonlinear evolution of the Rayleigh-Taylor instability driven by a strong blast wave. Single bubble motion is determined by an extension of previous buoyancy-drag models extended to the blast wave driven case, and a simple bubble merger law in the spirit of the Sharp-Wheeler model allows for the generation of larger scales. The blast wave driven case differs in several respects from the classical case of incompressible fluids in a uniform gravitational field. Because of material decompression in the rarefaction behind the blast front, the asymptotic bubble velocity and the merger time depend on time as well as the transverse scale and the drive. For planar blast waves, this precludes the emergence of a self-similar regime independent of the initial conditions. With higher-dimensional blast waves, divergence restores the properties necessary for the establishment of the self-similar state, but its establishment requires a very high initial characteristic mode number and a high Mach number for the incident blast wave.

  9. The Air Blast Wave from a Nuclear Explosion

    NASA Astrophysics Data System (ADS)

    Reines, Frederick

    The sudden, large scale release of energy in the explosion of a nuclear bomb in air gives rise, in addition to nuclear emanations such as neutrons and gamma rays, to an extremely hot, rapidly expanding mass of air.** The rapidly expanding air mass has an initial temperature in the vicinity of a few hundred thousand degrees and for this reason it glows in its early stages with an intensity of many suns. It is important that the energy density in this initial "ball of fire" is of the order of 3 × 103 times that found in a detonating piece of TNT and hence that the initial stages of the large scale air motion produced by a nuclear explosion has no counterpart in an ordinary. H. E. explosion. Further, the relatively low temperatures ˜2,000°C associated with the initial stages of an H. E. detonation implies that the thermal radiation which it emits is a relatively insignificant fraction of the total energy involves. This point is made more striking when it is remembered that the thermal energy emitted by a hot object varies directly with the temperature in the Rayleigh Jeans region appropriate to the present discussion. The expansion of the air mass heated by the nuclear reaction produces, in qualitatively the same manner as in an H.E. explosion or the bursting of a high pressure balloon, an intense sharp pressure pulse, a shock wave, in the atmosphere. As the pressure pulse spreads outward it weakens due to the combined effects of divergence and the thermodynamically irreversible nature of the shock wave. The air comprising such a pressure pulse or blast wave moves first radially outward and then back towards the center as the blast wave passes. Since a permanent outward displacement of an infinite mass of air would require unlimited energy, the net outward displacement of the air distant from an explosion must approach zero with increasing distance. As the distance from the explosion is diminished the net outward displacement due to irreversible shock heating of

  10. Mitigation of exploding-wire-generated blast-waves by aqueous foam

    NASA Astrophysics Data System (ADS)

    Liverts, M.; Ram, O.; Sadot, O.; Apazidis, N.; Ben-Dor, G.

    2015-07-01

    In this work, we implement an exploding wire technique to generate small-scale cylindrical blast waves in aqueous foam. The exploding wire system offers an easy to operate and effective tool for studying blast-wave/foam interaction related phenomena in real explosion scenarios. The mitigation of blast waves as a function of the thickness of the foam barrier is discussed and quantified. A fluid mixture pseudo-gas based numerical approach with the aid of the point explosion theory is used to separate the mitigation mechanisms into the near- and the far-field related groups and to analyze the contribution of each group to the overall losses of the blast wave energy.

  11. Spatially-resolved X-ray scattering measurements of a planar blast wave

    NASA Astrophysics Data System (ADS)

    Gamboa, E. J.; Keiter, P. A.; Drake, R. P.; Falk, K.; Montgomery, D. S.; Benage, J. F.

    2014-06-01

    We present X-ray scattering measurements characterizing the spatial temperature and ionization profile of a blast wave driven in a near-solid density foam. Several-keV X-rays scattered from a laser-driven blast wave in a carbon foam. We resolved the scattering in high resolution in space and wavelength to extract the plasma conditions along the propagation direction of the blast wave. We infer temperatures of 20-40 eV and ionizations of 2-4 in the shock and rarefaction regions of the blast wave. This range of measured ionization states allows for a detailed comparison between different models for the bound-free scattering. FLYCHK simulations of the temperature-ionization balance generally agree with the experimental values in the shocked region while consistently underestimating the ionization in the rarefaction.

  12. SPIKE PENETRATION IN BLAST-WAVE-DRIVEN INSTABILITIES

    SciTech Connect

    Drake, R. P.

    2012-01-10

    The problem of interest is the unstable growth of structure at density transitions affected by blast waves, which arise in natural environments such as core-collapse supernovae and in laboratory experiments. The resulting spikes of dense material, which penetrate the less dense material, develop broadened tips, but the degree of broadening varies substantially across both experiments and simulations. The variable broadening presumably produces variations in the drag experienced by the spike tips as they penetrate the less dense material. The present work has used semianalytic theory to address the question of how the variation in drag might affect the spike penetration, for cases in which the post-shock interface deceleration can be described by a power law in a normalized time variable. It did so by following the evolution of structure on the interface through the initial shock passage, the subsequent small-amplitude phase of Rayleigh-Taylor instability growth, and the later phase in which the spike growth involves the competition of buoyancy and drag. In all phases, the expansion of the system during its evolution was accounted for and was important. The calculated spike length is strongly affected by the drag attributed to spike tip broadening. One finds from such a calculation that it is not unreasonable for narrow spikes to keep up with the shock front of the blast wave. The implication is that the accuracy of prediction of spike penetration and consequent structure by simulations very likely depends on how accurately they treat the broadening of the spike tips and the associated drag. Experimental validation of spike morphology in simulations would be useful.

  13. Spike morphology in blast-wave-driven instability experiments

    SciTech Connect

    Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.; Fryxell, B.; Budde, A.; Hansen, J. F.; Miles, A. R.; Plewa, T.; Hearn, N.; Knauer, J.

    2010-05-15

    The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh-Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He-H interface during the explosion phase of a supernova. The experimental target is a 150 {mu}m thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 {mu}m and a wavelength of 71 {mu}m. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh-Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetration observed in the experiments. The amount of mass reaching the shock front is analyzed and potential causes for the spike morphology and the spikes reaching the shock are discussed. One such hypothesis is that these phenomena may be caused by magnetic pressure, generated by an azimuthal magnetic field produced by the plasma dynamics.

  14. Simulation of blast wave propagation from source to long distance with topography and atmospheric effects

    NASA Astrophysics Data System (ADS)

    Nguyen-Dinh, Maxime; Gainville, Olaf; Lardjane, Nicolas

    2015-10-01

    We present new results for the blast wave propagation from strong shock regime to the weak shock limit. For this purpose, we analyse the blast wave propagation using both Direct Numerical Simulation and an acoustic asymptotic model. This approach allows a full numerical study of a realistic pyrotechnic site taking into account for the main physical effects. We also compare simulation results with first measurements. This study is a part of the french ANR-Prolonge project (ANR-12-ASTR-0026).

  15. Non-adiabatic imprints on the electron wave packet in strong field ionization with circular polarization

    NASA Astrophysics Data System (ADS)

    Hofmann, C.; Zimmermann, T.; Zielinski, A.; Landsman, A. S.

    2016-04-01

    The validity of the adiabatic approximation in strong field ionization under typical experimental conditions has recently become a topic of great interest. Experimental results have been inconclusive, in part, due to the uncertainty in experimental calibration of intensity. Here we turn to the time-dependent Schrödinger equation, where all the laser parameters are known exactly. We find that the centre of the electron momentum distribution (typically used for calibration of elliptically and circularly polarized light) is sensitive to non-adiabatic effects, leading to intensity shifts in experimental data that can significantly affect the interpretation of results. On the other hand, the transverse momentum spread in the plane of polarization is relatively insensitive to such effects, even in the Keldysh parameter regime approaching γ ≈ 3. This suggests the transverse momentum spread in the plane of polarization as a good alternative to the usual calibration method, particularly for experimental investigation of non-adiabatic effects using circularly polarized light.

  16. Modeling of weak blast wave propagation in the lung.

    PubMed

    D'yachenko, A I; Manyuhina, O V

    2006-01-01

    Blast injuries of the lung are the most life-threatening after an explosion. The choice of physical parameters responsible for trauma is important to understand its mechanism. We developed a one-dimensional linear model of an elastic wave propagation in foam-like pulmonary parenchyma to identify the possible cause of edema due to the impact load. The model demonstrates different injury localizations for free and rigid boundary conditions. The following parameters were considered: strain, velocity, pressure in the medium and stresses in structural elements, energy dissipation, parameter of viscous criterion. Maximum underpressure is the most suitable wave parameter to be the criterion for edema formation in a rabbit lung. We supposed that observed scattering of experimental data on edema severity is induced by the physiological variety of rabbit lungs. The criterion and the model explain this scattering. The model outlines the demands for experimental data to make an unambiguous choice of physical parameters responsible for lung trauma due to impact load.

  17. Full-Trajectory Diagnosis of Laser-Driven Radiative Blast Waves in Search of Thermal Plasma Instabilities

    SciTech Connect

    Moore, A. S.; Gumbrell, E. T.; Lazarus, J.; Hohenberger, M.; Robinson, J. S.; Smith, R. A.; Plant, T. J. A.; Symes, D. R.; Dunne, M.

    2008-02-08

    Experimental investigations into the dynamics of cylindrical, laser-driven, high-Mach-number shocks are used to study the thermal cooling instability predicted to occur in astrophysical radiative blast waves. A streaked Schlieren technique measures the full blast-wave trajectory on a single-shot basis, which is key for observing shock velocity oscillations. Electron density profiles and deceleration parameters associated with radiative blast waves were recorded, enabling the calculation of important blast-wave parameters including the fraction of radiated energy, {epsilon}, as a function of time for comparison with radiation-hydrodynamics simulations.

  18. Full-trajectory diagnosis of laser-driven radiative blast waves in search of thermal plasma instabilities.

    PubMed

    Moore, A S; Gumbrell, E T; Lazarus, J; Hohenberger, M; Robinson, J S; Smith, R A; Plant, T J A; Symes, D R; Dunne, M

    2008-02-01

    Experimental investigations into the dynamics of cylindrical, laser-driven, high-Mach-number shocks are used to study the thermal cooling instability predicted to occur in astrophysical radiative blast waves. A streaked Schlieren technique measures the full blast-wave trajectory on a single-shot basis, which is key for observing shock velocity oscillations. Electron density profiles and deceleration parameters associated with radiative blast waves were recorded, enabling the calculation of important blast-wave parameters including the fraction of radiated energy, epsilon, as a function of time for comparison with radiation-hydrodynamics simulations. PMID:18352379

  19. Challenging Some Contemporary Views of Coronal Mass Ejections. I. The Case for Blast Waves

    NASA Astrophysics Data System (ADS)

    Howard, T. A.; Pizzo, V. J.

    2016-06-01

    Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced the “traditional” view that CMEs were blast waves driven by solar flares. While the flux rope CME narrative is supported by a vast quantity of measurements made over five decades, it does not adequately describe every observation of what have been termed CME-related phenomena. In this paper we present evidence that some large-scale coronal eruptions, particularly those associated with EIT waves, exhibit characteristics that are more consistent with a blast wave originating from a localized region (such as a flare site) rather than a large-scale structure driven by an intrinsic flux rope. We present detailed examples of CMEs that are suspected blast waves and flux ropes, and show that of our small sample of 22 EIT-wave-related CMEs, 91% involve a blast wave as at least part of the eruption, and 50% are probably blast waves exclusively. We conclude with a description of possible signatures to look for in determining the difference between the two types of CMEs and with a discussion on modeling efforts to explore this possibility.

  20. Computation of viscous blast wave solutions with an upwind finite volume method

    NASA Technical Reports Server (NTRS)

    Molvik, Gregory A.

    1987-01-01

    A fully conservative, viscous, implicit, upwind, finite-volume scheme for the thin-layer Navier-Stokes equations is described with application to blast wave flow fields. In this scheme, shocks are captured without the oscillations typical of central differencing techniques and wave speeds are accurately predicted. The finite volume philosophy ensures conservation and since boundary conditions are also treated conservatively, accurate reflections of waves from surfaces are assured. Viscous terms in the governing equations are treated in a manner consistent with the finite volume philosophy, resulting in very accurate prediction of boundary layer quantities. Numerical results are presented for four viscous problems: a steady boundary layer, a shock-induced boundary layer, a blast wave/cylinder interaction and a blast wave/supersonic missile interaction. Comparisons of the results with an established boundary layer code, similarity solution, and experimental data show excellent agreement.

  1. Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology

    PubMed Central

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

    A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

  2. Blast shock wave mitigation using the hydraulic energy redirection and release technology.

    PubMed

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

    A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

  3. Blast shock wave mitigation using the hydraulic energy redirection and release technology.

    PubMed

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

    A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel.

  4. Analysis of reflected blast wave pressure profiles in a confined room

    NASA Astrophysics Data System (ADS)

    Sauvan, P. E.; Sochet, I.; Trélat, S.

    2012-05-01

    To understand the blast effects of confined explosions, it is necessary to study the characteristic parameters of the blast wave in terms of overpressure, impulse and arrival time. In a previous study, experiments were performed using two different scales of a pyrotechnic workshop. The main purpose of these experiments was to compare the TNT equivalent for solid and gaseous explosives in terms of mass to define a TNT equivalent in a reflection field and to validate the similitude between real and small scales. To study the interactions and propagations of the reflected shock waves, the present study was conducted by progressively building a confined volume around the charge. In this way, the influence of each wall and the origins of the reflected shock waves can be determined. The purpose of this paper is to report the blast wave interactions that resulted from the detonation of a stoichiometric propane-oxygen mixture in a confined room.

  5. A blast wave from the 1843 eruption of η Carinae

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2008-09-01

    Very massive stars shed much of their mass in violent precursor eruptions as luminous blue variables (LBVs) before reaching their most likely end as supernovae, but the cause of LBV eruptions is unknown. The nineteenth-century eruption of η Carinae, the prototype of these events, ejected about 12 solar masses at speeds of 650kms-1, with a kinetic energy of almost 1050erg (ref. 4). Some faster material with speeds up to 1,000-2,000kms-1 had previously been reported but its full distribution was unknown. Here I report observations of much faster material with speeds up to 3,500-6,000kms-1, reaching farther from the star than the fastest material in previous reports. This fast material roughly doubles the kinetic energy of the nineteenth-century event and suggests that it released a blast wave now propagating ahead of the massive ejecta. As a result, η Carinae's outer shell now mimics a low-energy supernova remnant. The eruption has usually been discussed in terms of an extreme wind driven by the star's luminosity, but the fast material reported here indicates that it may have been powered by a deep-seated explosion rivalling a supernova, perhaps triggered by the pulsational pair instability. This may alter interpretations of similar events seen in other galaxies.

  6. Numerical study of water mitigation effects on blast wave

    NASA Astrophysics Data System (ADS)

    Cheng, M.; Hung, K. C.; Chong, O. Y.

    2005-11-01

    The mitigating effect of a water wall on the generation and propagation of blast waves of a nearby explosive has been investigated using a numerical approach. A multimaterial Eulerian finite element technique is used to study the influence of the design parameters, such as the water-to-explosive weight ratio, the water wall thickness, the air-gap and the cover area ratio of water on the effectiveness of the water mitigation concept. In the computational model, the detonation gases are modelled with the standard Jones Wilkins Lee (JWL) equation of state. Water, on the other hand, is treated as a compressible fluid with the Mie Gruneisen equation of state model. The validity of the computational model is checked against a limited amount of available experimental data, and the influence of mesh sizes on the convergence of results is also discussed. From the results of the extensive numerical experiments, it is deduced that firstly, the presence of an air-gap reduces the effectiveness of the water mitigator. Secondly, the higher the water-to-explosive weight ratio, the more significant is the reduction in peak pressure of the explosion. Typically, water-to-explosive weight ratios in the range of 1 3 are found to be most practical.

  7. Prospects for studying how high-intensity compression waves cause damage in human blast injuries

    NASA Astrophysics Data System (ADS)

    Brown, Katherine; Bo, Chiara; Ramaswamy, Arul; Masouros, Spiros; Newell, Nicolas; Hill, Adam; Clasper, Jon; Bull, Anthony; Proud, William

    2011-06-01

    Blast injuries arising from improvised explosive devices are often complex leading to long-term disability in survivors. There is an urgent need to mitigate against the effects of blast that lead to these injuries, and to also improve post-traumatic therapeutic treatments related to problems associated with damage and healing processes and infections. We have initiated multidisciplinary studies to develop experimental facilities and strategies for analyzing the effects blast waves upon the human body, from cellular through to skeletal functions. This work is supported by the Atomic Weapons Establishment and the Defence Science and Technology Laboratory, UK.

  8. Interaction between blast wave and reticulated foam: assessing the potential for auditory protection systems

    NASA Astrophysics Data System (ADS)

    Wilgeroth, J. M.; Nguyen, T.-T. N.; Proud, W. G.

    2014-05-01

    Injuries to the tympanic membrane (ear drum) are particularly common in individuals subjected to blast overpressure such as military personnel engaged in conflict. Here, the interaction between blast wave and reticulated foams of varying density and thickness has been investigated using shock tube apparatus. The degree of mitigation afforded by the foam samples is discussed in relation to an injury threshold which has been suggested by others for the tympanic membrane.

  9. Experimental Investigation of the Interaction of Blast Waves Generated by Exploding Wires using Background Oriented Schlieren

    NASA Astrophysics Data System (ADS)

    Gross, Jonathan; Eliasson, Veronica

    2015-11-01

    Work has been performed to experimentally characterize the interaction of a multiple blast waves. The blast waves were generated using an exploding wire system. This system can store up to 400 J of energy in a high voltage capacitor bank. By discharging the capacitors through wires of a diameter of 150 μm it was possible to produce blast waves with Mach numbers as high as 2.3 at a distance of 40 mm from the center of the blast. A parametric study was performed to measure the behavior of the shocks for a variety of wire thicknesses, voltages, and separation distances. Additionally a background oriented schlieren system was used to quantify the flowfield behind the shocks. The interaction of the shocks featured expected nonlinear phenomena such as the presence of Mach stems, and showed good agreement with results in the shock wave literature. This investigation lays the groundwork for subsequent research that will use exploding wires to experimentally reproduce conditions investigated numerically, in which the effects of multiple converging blast waves on a central target were investigated.

  10. POLYCYCLIC AROMATIC HYDROCARBON PROCESSING IN THE BLAST WAVE OF THE SUPERNOVA REMNANT N132D

    SciTech Connect

    Tappe, A.; Rho, J.; Micelotta, E. R.

    2012-08-01

    We present Spitzer Infrared Spectrograph 14-36 {mu}m mapping observations of the supernova remnant N132D in the Large Magellanic Cloud. This study focuses on the processing of polycyclic aromatic hydrocarbons (PAHs) that we previously identified in the southern blast wave. The mid-infrared spectra show strong continuum emission from shock-heated dust and a unique, nearly featureless plateau in the 15-20 {mu}m region, which we attribute to PAH molecules. The typical PAH emission bands observed in the surrounding interstellar medium ahead of the blast wave disappear, which indicates shock processing of PAH molecules. The PAH plateau appears most strongly at the outer edge of the blast wave and coincides with diffuse X-ray emission that precedes the brightest X-ray and optical filaments. This suggests that PAH molecules in the surrounding medium are swept up and processed in the hot gas of the blast wave shock, where they survive the harsh conditions long enough to be detected. We also observe a broad emission feature at 20 {mu}m appearing with the PAH plateau. We speculate that this feature is either due to FeO dust grains or connected to the processing of PAHs in the supernova blast wave shock.

  11. Quick reproduction of blast-wave flow-field properties of nuclear, TNT, and ANFO explosions

    NASA Astrophysics Data System (ADS)

    Groth, C. P. T.

    1986-04-01

    In many instances, extensive blast-wave flow-field properties are required in gasdynamics research studies of blast-wave loading and structure response, and in evaluating the effects of explosions on their environment. This report provides a very useful computer code, which can be used in conjunction with the DNA Nuclear Blast Standard subroutines and code, to quickly reconstruct complete and fairly accurate blast-wave data for almost any free-air (spherical) and surface-burst (hemispherical) nuclear, trinitrotoluene (TNT), or ammonium nitrate-fuel oil (ANFO) explosion. This code is capable of computing all of the main flow properties as functions of radius and time, as well as providing additional information regarding air viscosity, reflected shock-wave properties, and the initial decay of the flow properties just behind the shock front. Both spatial and temporal distributions of the major blast-wave flow properties are also made readily available. Finally, provisions are also included in the code to provide additional information regarding the peak or shock-front flow properties over a range of radii, for a specific explosion of interest.

  12. Energy spectrum analysis of blast waves based on an improved Hilbert-Huang transform

    NASA Astrophysics Data System (ADS)

    Li, L.; Wang, F.; Shang, F.; Jia, Y.; Zhao, C.; Kong, D.

    2016-07-01

    Using the improved Hilbert-Huang transform (HHT), this paper investigates the problems of analysis and interpretation of the energy spectrum of a blast wave. It has been previously established that the energy spectrum is an effective feature by which to characterize a blast wave. In fact, the higher the energy spectra in a frequency band of a blast wave, the greater the damage to a target in the same frequency band. However, most current research focuses on analyzing wave signals in the time domain or frequency domain rather than considering the energy spectrum. We propose here an improved HHT method combined with a wavelet packet to extract the energy spectrum feature of a blast wave. When applying the HHT, the signal is first roughly decomposed into a series of intrinsic mode functions (IMFs) by empirical mode decomposition. The wavelet packet method is then performed on each IMF to eliminate noise on the energy spectrum. Second, a coefficient is introduced to remove unrelated IMFs. The energy of each instantaneous frequency can be derived through the Hilbert transform. The energy spectrum can then be obtained by adding up all the components after the wavelet packet filters and screens them through a coefficient to obtain the effective IMFs. The effectiveness of the proposed method is demonstrated by 12 groups of experimental data, and an energy attenuation model is established based on the experimental data. The improved HHT is a precise method for blast wave signal analysis. For other shock wave signals from blasting experiments, an energy frequency time distribution and energy spectrum can also be obtained through this method, allowing for more practical applications.

  13. Adiabatic description of capture into resonance and surfatron acceleration of charged particles by electromagnetic waves.

    PubMed

    Artemyev, A V; Neishtadt, A I; Zelenyi, L M; Vainchtein, D L

    2010-12-01

    We present an analytical and numerical study of the surfatron acceleration of nonrelativistic charged particles by electromagnetic waves. The acceleration is caused by capture of particles into resonance with one of the waves. We investigate capture for systems with one or two waves and provide conditions under which the obtained results can be applied to systems with more than two waves. In the case of a single wave, the once captured particles never leave the resonance and their velocity grows linearly with time. However, if there are two waves in the system, the upper bound of the energy gain may exist and we find the analytical value of that bound. We discuss several generalizations including the relativistic limit, different wave amplitudes, and a wide range of the waves' wavenumbers. The obtained results are used for qualitative description of some phenomena observed in the Earth's magnetosphere.

  14. Adiabatic description of capture into resonance and surfatron acceleration of charged particles by electromagnetic waves.

    PubMed

    Artemyev, A V; Neishtadt, A I; Zelenyi, L M; Vainchtein, D L

    2010-12-01

    We present an analytical and numerical study of the surfatron acceleration of nonrelativistic charged particles by electromagnetic waves. The acceleration is caused by capture of particles into resonance with one of the waves. We investigate capture for systems with one or two waves and provide conditions under which the obtained results can be applied to systems with more than two waves. In the case of a single wave, the once captured particles never leave the resonance and their velocity grows linearly with time. However, if there are two waves in the system, the upper bound of the energy gain may exist and we find the analytical value of that bound. We discuss several generalizations including the relativistic limit, different wave amplitudes, and a wide range of the waves' wavenumbers. The obtained results are used for qualitative description of some phenomena observed in the Earth's magnetosphere. PMID:21198098

  15. Propagation of the shock wave generated from excimer laser heating of aluminum targets in comparison with ideal blast wave theory

    NASA Astrophysics Data System (ADS)

    Jeong, S. H.; Greif, R.; Russo, R. E.

    1998-05-01

    Propagation of the shock wave generated during pulsed laser heating of aluminum targets was measured utilizing a probe beam deflection technique. The transit time of the laser-generated shock wave was compared with that predicted from the Sedov-Taylor solution for an ideal spherical blast wave. It was found that the most important parameters for the laser-generated shock wave to be consistent with the theoretically predicted propagation are the ambient pressure and the laser beam spot size. The prediction for laser energy conversion into the laser-induced vapor flow using the Sedov-Taylor solution overestimated the energy coupling efficiency, indicating a difference between a laser-induced gas-dynamic flow and an ideal blast wave.

  16. On the adiabatic walking of plasma waves in a pulsar magnetosphere

    SciTech Connect

    Melikidze, George I.; Gil, Janusz; Mitra, Dipanjan E-mail: jag@astro.ia.uz.zgora.pl

    2014-10-20

    The pulsar radio emission is generated in the near magnetosphere of the neutron star, and it must propagate through the rest of it to emerge into the interstellar medium. An important issue is whether this propagation affects the planes of polarization of the generated radiation. Observationally, there is sufficient evidence that the emerging radiation is polarized parallel or perpendicular to the magnetic field line planes that should be associated with the ordinary (O) and extraordinary (X) plasma modes, respectively, excited by some radiative process. This strongly suggests that the excited X and O modes are not affected by the so-called adiabatic walking that causes a slow rotation of polarization vectors. In this paper, we demonstrate that the conditions for adiabatic walking are not fulfilled within the soliton model of pulsar radio emission, in which the coherent curvature radiation occurs at frequencies much lower than the characteristic plasma frequency, The X mode propagates freely and observationally represents the primary polarization mode. The O mode has difficulty escaping from the pulsar plasma; however, it is sporadically observed as a weaker secondary polarization mode. We discuss a possible scenario under which the O mode can also escape from the plasma and reach an observer.

  17. Rapid optimization of blast wave mitigation strategies using Quiet Direct Simulation and Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Smith, Matthew R.; Kuo, Fang-An; Hsieh, Chih-Wei; Yu, Jen-Perng; Wu, Jong-Shinn; Ferguson, Alex

    2010-06-01

    Presented is a rapid calculation tool for the optimization of blast wave related mitigation strategies. The motion of gas resulting from a blast wave (specified by the user) is solved by the Quiet Direct Simulation (QDS) method - a rapid kinetic theory-based finite volume method. The optimization routine employed is a newly developed Genetic Algorithm (GA) which is demonstrated to be similar to a Differential Evolution (DE) scheme with several modifications. In any Genetic Algorithm, individuals contain genetic information which is passed on to newly created individuals in successive generations. The results from unsteady QDS simulations are used to determine the individual's "genetic fitness" which is employed by the proposed Genetic Algorithm during the reproduction process. The combined QDS/GA algorithm is applied to various test cases and finally the optimization of a non-trivial blast wave mitigation strategy. Both QDS and the proposed GA are demonstrated to perform with minimal computational expense while accurately solving the optimization problems presented.

  18. Blast wave formation of the extended stellar shells surrounding elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Williams, R. E.; Christiansen, W. A.

    1985-01-01

    The existence of stellar shells at large distances from isolated elliptical galaxies is explained in terms of a blast wave associated with an active nucleus phase early in the history of the galaxy. The blast wave sweeps the initial interstellar medium out of the galaxy into an expanding shell which radiatively cools behind its leading shock front. Cooling of the shell following turnoff of the nucleus activity, which keeps the shell photoionized, leads to a brief epoch of star formation which is terminated by heating of the shell from supernovae and UV radiation from massive stars. The stars so formed follow similar, highly radial, bound orbits, moving in phase with each other and spending much of their time near apogalacteum, thus taking on the appearance of a shell. Multiple shells may be produced when conditions allow repeated episodes of shell cooling and supernovae heating to occur in the blast wave.

  19. Near-Field Characterization of Radial and Axial Blast Waves From a Cylindrical Explosive Charge

    NASA Astrophysics Data System (ADS)

    McNesby, Kevin; Homan, Barrie

    This paper uses experiment (high speed imaging) and simulation (ALE-3D) to investigate radial and axial blast waves produced by uncased, cylindrical charges of TNT (trinitrotoluene). Recently there has been work reported on predicting secondary blast waves in the explosive mid-field (approximately 1 meter from charge center of mass) for cylindrical charges of RDX (trimethylenetrinitramine)/binder formulations. The work we will present seeks to provide complementary information in the explosive near-field, including the approach to chemical ``freeze out'', for end-detonated, right circular cylinders of TNT. Additionally, this work attempts to retrieve state variables (temperature, pressure, velocities) from high-definition images of the explosive event. Keywords: cylindrical charges, blast, shock waves

  20. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects.

    PubMed

    Courtney, Amy C; Andrusiv, Lubov P; Courtney, Michael W

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile. PMID:22559580

  1. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

    NASA Astrophysics Data System (ADS)

    Courtney, Amy C.; Andrusiv, Lubov P.; Courtney, Michael W.

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

  2. Simulation of blast-induced early-time intracranial wave physics leading to traumatic brain injury.

    PubMed

    Taylor, Paul A; Ford, Corey C

    2009-06-01

    The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm3 voxels) five material model of the human head was created by segmentation of color cryosections from the Visible Human Female data set. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior, and lateral directions. Three-dimensional plots of maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric stress within the first 2 ms of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 ms time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early-time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI. PMID:19449961

  3. Effects of internal heat transfer on the structure of self-similar blast waves

    NASA Technical Reports Server (NTRS)

    Ghoniem, A. F.; Berger, S. A.; Oppenheim, A. K.; Kamel, M. M.

    1982-01-01

    An analysis of the problem of self-similar, nonadiabatic blast waves, where both conduction and radiation are allowed to take place, show the problem to be reducible to the integration of a system of six coupled nonlinear ordinary differential equations. Consideration of these equations shows that although radiation tends to produce uniform fields through temperature gradient attenuation, all the energy carried by radiation is deposited on the front and the bounding shock becomes increasingly overdriven. When conduction is taken into account, the distribution of gasdynamic parameters in blast waves in the case of Rosseland diffusion radiation is more uniform than in the case of the Planck emission radiation.

  4. Ion thermal effects on slow mode solitary waves in plasmas with two adiabatic ion species

    SciTech Connect

    Nsengiyumva, F. Hellberg, M. A. Mace, R. L.

    2015-09-15

    Using both the Sagdeev and Korteweg-de Vries (KdV) methods, ion thermal effects on slow mode ion acoustic solitons and double layers are investigated in a plasma with two adiabatic positive ion species. It is found that reducing the gap between the two ion thermal speeds by increasing the relative temperature of the cool ions increases the typical soliton/double layer speeds for all values of the ion-ion density ratio and reduces the range in the density ratio that supports double layers. The effect of increasing the relative cool ion temperature on the soliton/double layer amplitudes depends on the relative densities. For lower values of the ion density ratio, an increase in cool ion temperature leads to a significant decrease in soliton/double layer amplitude, so one may find that solitons of all permissible speeds lie within the range of KdV theory.

  5. Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

    SciTech Connect

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T.

    2013-12-15

    Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

  6. Adiabatically tapered hyperbolic metamaterials for dispersion control of high-k waves.

    PubMed

    West, Paul R; Kinsey, Nathaniel; Ferrera, Marcello; Kildishev, Alexander V; Shalaev, Vladimir M; Boltasseva, Alexandra

    2015-01-14

    Hyperbolic metamaterials (HMMs) have shown great promise in the optical and quantum communities due to their extremely large, broadband photonic density of states. This feature is a direct consequence of supporting photonic modes with unbounded k-vectors. While these materials support such high-k waves, they are intrinsically confined inside the HMM and cannot propagate into the far-field, rendering them impractical for many applications. Here, we demonstrate how the magnitude of k-vectors can be engineered as the propagating radiation passes through media of differing dispersion relations (including type II HMMs and dielectrics) in the in-plane direction. The total outcoupling efficiency of waves in the in-plane direction is shown to be on average 2 orders of magnitude better than standard out-of-plane outcoupling methods. In addition, the outcoupling can be further enhanced using a proposed tapered HMM waveguide that is fabricated using a shadowed glancing angle deposition technique; thereby proving the feasibility of the proposed device. Applications for this technique include converting high-k waves to low-k waves that can be out-coupled into free-space and creating extremely high-k waves that are quickly quenched. Most importantly, this method of in-plane outcoupling acts as a bridge through which waves can cross between the regimes of low-k waves in classical dielectric materials and the high-k waves in HMMs with strongly reduced reflective losses.

  7. Frequency-Dependent Attenuation of Blasting Vibration Waves

    NASA Astrophysics Data System (ADS)

    Zhou, Junru; Lu, Wenbo; Yan, Peng; Chen, Ming; Wang, Gaohui

    2016-10-01

    The dominant frequency, in addition to the peak particle velocity, is a critical factor for assessing adverse effects of the blasting vibration on surrounding structures; however, it has not been fully considered in blasting design. Therefore, the dominant frequency-dependent attenuation mechanism of blast-induced vibration is investigated in the present research. Starting with blasting vibration induced by a spherical charge propagating in an infinite viscoelastic medium, a modified expression of the vibration amplitude spectrum was derived to reveal the frequency dependency of attenuation. Then, ground vibration induced by more complex and more commonly used cylindrical charge that propagates in a semi-infinite viscoelastic medium was analyzed by numerical simulation. Results demonstrate that the absorptive property of the medium results in the frequency attenuation versus distance, whereas a rapid drop or fluctuation occurs during the attenuation of ground vibration. Fluctuation usually appears at moderate to far field, and the dominant frequency generally decreases to half the original value when rapid drop occurs. The decay rate discrepancy between different frequency components and the multimodal structure of vibration spectrum lead to the unsmooth frequency-dependent attenuation. The above research is verified by two field experiments. Furthermore, according to frequency-based vibration standards, frequency drop and fluctuation should be considered when evaluating blast safety. An optimized piecewise assessment is proposed for more accurate evaluation: With the frequency drop point as the breakpoint, the assessment is divided into two independent sections along the propagating path.

  8. Nonlinear propagation of high-frequency energy from blast waves as it pertains to bat hearing

    NASA Astrophysics Data System (ADS)

    Loubeau, Alexandra

    Close exposure to blast noise from military weapons training can adversely affect the hearing of both humans and wildlife. One concern is the effect of high-frequency noise from Army weapons training on the hearing of endangered bats. Blast wave propagation measurements were conducted to investigate nonlinear effects on the development of blast waveforms as they propagate from the source. Measurements were made at ranges of 25, 50, and 100 m from the blast. Particular emphasis was placed on observation of rise time variation with distance. Resolving the fine shock structure of blast waves requires robust transducers with high-frequency capability beyond 100 kHz, hence the limitations of traditional microphones and the effect of microphone orientation were investigated. Measurements were made with a wide-bandwidth capacitor microphone for comparison with conventional 3.175-mm (⅛-in.) microphones with and without baffles. The 3.175-mm microphone oriented at 90° to the propagation direction did not have sufficient high-frequency response to capture the actual rise times at a range of 50 m. Microphone baffles eliminate diffraction artifacts on the rise portion of the measured waveform and therefore allow for a more accurate measurement of the blast rise time. The wide-band microphone has an extended high-frequency response and can resolve shorter rise times than conventional microphones. For a source of 0.57 kg (1.25 lb) of C-4 plastic explosive, it was observed that nonlinear effects steepened the waveform, thereby decreasing the shock rise time, from 25 to 50 m. At 100m, the rise times had increased slightly. For comparison to the measured blast waveforms, several models of nonlinear propagation are applied to the problem of finite-amplitude blast wave propagation. Shock front models, such as the Johnson and Hammerton model, and full-waveform marching algorithms, such as the Anderson model, are investigated and compared to experimental results. The models

  9. Pathophysiology of the inner ear after blast injury caused by laser-induced shock wave

    PubMed Central

    Niwa, Katsuki; Mizutari, Kunio; Matsui, Toshiyasu; Kurioka, Takaomi; Matsunobu, Takeshi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro; Kobayashi, Yasushi

    2016-01-01

    The ear is the organ that is most sensitive to blast overpressure, and ear damage is most frequently seen after blast exposure. Blast overpressure to the ear results in sensorineural hearing loss, which is untreatable and is often associated with a decline in the quality of life. In this study, we used a rat model to demonstrate the pathophysiological and structural changes in the inner ear that replicate pure sensorineural hearing loss associated with blast injury using laser-induced shock wave (LISW) without any conductive hearing loss. Our results indicate that threshold elevation of the auditory brainstem response (ABR) after blast exposure was primarily caused by outer hair cell dysfunction induced by stereociliary bundle disruption. The bundle disruption pattern was unique; disturbed stereocilia were mostly observed in the outermost row, whereas those in the inner and middle rows stereocilia remained intact. In addition, the ABR examination showed a reduction in wave I amplitude without elevation of the threshold in the lower energy exposure group. This phenomenon was caused by loss of the synaptic ribbon. This type of hearing dysfunction has recently been described as hidden hearing loss caused by cochlear neuropathy, which is associated with tinnitus or hyperacusis. PMID:27531021

  10. Pathophysiology of the inner ear after blast injury caused by laser-induced shock wave.

    PubMed

    Niwa, Katsuki; Mizutari, Kunio; Matsui, Toshiyasu; Kurioka, Takaomi; Matsunobu, Takeshi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro; Kobayashi, Yasushi

    2016-01-01

    The ear is the organ that is most sensitive to blast overpressure, and ear damage is most frequently seen after blast exposure. Blast overpressure to the ear results in sensorineural hearing loss, which is untreatable and is often associated with a decline in the quality of life. In this study, we used a rat model to demonstrate the pathophysiological and structural changes in the inner ear that replicate pure sensorineural hearing loss associated with blast injury using laser-induced shock wave (LISW) without any conductive hearing loss. Our results indicate that threshold elevation of the auditory brainstem response (ABR) after blast exposure was primarily caused by outer hair cell dysfunction induced by stereociliary bundle disruption. The bundle disruption pattern was unique; disturbed stereocilia were mostly observed in the outermost row, whereas those in the inner and middle rows stereocilia remained intact. In addition, the ABR examination showed a reduction in wave I amplitude without elevation of the threshold in the lower energy exposure group. This phenomenon was caused by loss of the synaptic ribbon. This type of hearing dysfunction has recently been described as hidden hearing loss caused by cochlear neuropathy, which is associated with tinnitus or hyperacusis.

  11. Pathophysiology of the inner ear after blast injury caused by laser-induced shock wave.

    PubMed

    Niwa, Katsuki; Mizutari, Kunio; Matsui, Toshiyasu; Kurioka, Takaomi; Matsunobu, Takeshi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro; Kobayashi, Yasushi

    2016-01-01

    The ear is the organ that is most sensitive to blast overpressure, and ear damage is most frequently seen after blast exposure. Blast overpressure to the ear results in sensorineural hearing loss, which is untreatable and is often associated with a decline in the quality of life. In this study, we used a rat model to demonstrate the pathophysiological and structural changes in the inner ear that replicate pure sensorineural hearing loss associated with blast injury using laser-induced shock wave (LISW) without any conductive hearing loss. Our results indicate that threshold elevation of the auditory brainstem response (ABR) after blast exposure was primarily caused by outer hair cell dysfunction induced by stereociliary bundle disruption. The bundle disruption pattern was unique; disturbed stereocilia were mostly observed in the outermost row, whereas those in the inner and middle rows stereocilia remained intact. In addition, the ABR examination showed a reduction in wave I amplitude without elevation of the threshold in the lower energy exposure group. This phenomenon was caused by loss of the synaptic ribbon. This type of hearing dysfunction has recently been described as hidden hearing loss caused by cochlear neuropathy, which is associated with tinnitus or hyperacusis. PMID:27531021

  12. Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats.

    PubMed

    Awwad, Hibah O; Gonzalez, Larry P; Tompkins, Paul; Lerner, Megan; Brackett, Daniel J; Awasthi, Vibhudutta; Standifer, Kelly M

    2015-01-01

    Physiological alterations, anxiety, and cognitive disorders are strongly associated with blast-induced traumatic brain injury (blast TBI), and are common symptoms in service personnel exposed to blasts. Since 2006, 25,000-30,000 new TBI cases are diagnosed annually in U.S. Service members; increasing evidence confirms that primary blast exposure causes diffuse axonal injury and is often accompanied by altered behavioral outcomes. Behavioral and acute metabolic effects resulting from blast to the head in the absence of thoracic contributions from the periphery were examined, following a single blast wave directed to the head of male Sprague-Dawley rats protected by a lead shield over the torso. An 80 psi head blast produced cognitive deficits that were detected in working memory. Blast TBI rats displayed increased anxiety as determined by elevated plus maze at day 9 post-blast compared to sham rats; blast TBI rats spent significantly more time than the sham controls in the closed arms (p < 0.05; n = 8-11). Interestingly, anxiety symptoms were absent at days 22 and 48 post-blast. Instead, blast TBI rats displayed increased rearing behavior at day 48 post-blast compared to sham rats. Blast TBI rats also exhibited suppressed acoustic startle responses, but similar pre-pulse inhibition at day 15 post-blast compared to sham rats. Acute physiological alterations in cerebral glucose metabolism were determined by positron emission tomography 1 and 9 days post-blast using (18)F-fluorodeoxyglucose ((18)F-FDG). Global glucose uptake in blast TBI rat brains increased at day 1 post-blast (p < 0.05; n = 4-6) and returned to sham levels by day 9. Our results indicate a transient increase in cerebral metabolism following a blast injury. Markers for reactive astrogliosis and neuronal damage were noted by immunoblotting motor cortex tissue from day 10 post-blast in blast TBI rats compared to sham controls (p < 0.05; n = 5-6). PMID:26136722

  13. Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats

    PubMed Central

    Awwad, Hibah O.; Gonzalez, Larry P.; Tompkins, Paul; Lerner, Megan; Brackett, Daniel J.; Awasthi, Vibhudutta; Standifer, Kelly M.

    2015-01-01

    Physiological alterations, anxiety, and cognitive disorders are strongly associated with blast-induced traumatic brain injury (blast TBI), and are common symptoms in service personnel exposed to blasts. Since 2006, 25,000–30,000 new TBI cases are diagnosed annually in U.S. Service members; increasing evidence confirms that primary blast exposure causes diffuse axonal injury and is often accompanied by altered behavioral outcomes. Behavioral and acute metabolic effects resulting from blast to the head in the absence of thoracic contributions from the periphery were examined, following a single blast wave directed to the head of male Sprague-Dawley rats protected by a lead shield over the torso. An 80 psi head blast produced cognitive deficits that were detected in working memory. Blast TBI rats displayed increased anxiety as determined by elevated plus maze at day 9 post-blast compared to sham rats; blast TBI rats spent significantly more time than the sham controls in the closed arms (p < 0.05; n = 8–11). Interestingly, anxiety symptoms were absent at days 22 and 48 post-blast. Instead, blast TBI rats displayed increased rearing behavior at day 48 post-blast compared to sham rats. Blast TBI rats also exhibited suppressed acoustic startle responses, but similar pre-pulse inhibition at day 15 post-blast compared to sham rats. Acute physiological alterations in cerebral glucose metabolism were determined by positron emission tomography 1 and 9 days post-blast using 18F-fluorodeoxyglucose (18F-FDG). Global glucose uptake in blast TBI rat brains increased at day 1 post-blast (p < 0.05; n = 4–6) and returned to sham levels by day 9. Our results indicate a transient increase in cerebral metabolism following a blast injury. Markers for reactive astrogliosis and neuronal damage were noted by immunoblotting motor cortex tissue from day 10 post-blast in blast TBI rats compared to sham controls (p < 0.05; n = 5–6). PMID:26136722

  14. Prospects for studying how high-intensity compression waves cause damage in human blast injuries

    NASA Astrophysics Data System (ADS)

    Brown, Katherine; Bo, Chiara; Masouros, Spyros; Ramasamy, Arul; Newell, Nicolas; Bonner, Timothy; Balzer, Jens; Hill, Adam; Clasper, Jon; Bull, Anthony; Proud, William

    2012-03-01

    Since World War I, explosions have accounted for over 70% of all injuries in conflict. With the development of improved personnel protection of the torso, improved medical care and faster aeromedical evacuation, casualties are surviving with more severe injuries to the extremities. Understanding the processes involved in the transfer of blast-induced shock waves through biological tissues is essential for supporting efforts aimed at mitigating and treating blast injury. Given the inherent heterogeneities in the human body, we argue that studying these processes demands a highly integrated approach requiring expertise in shock physics, biomechanics and fundamental biological processes. This multidisciplinary systems approach enables one to develop the experimental framework for investigating the material properties of human tissues that are subjected to high compression waves in blast conditions and the fundamental cellular processes altered by this type of stimuli. Ultimately, we hope to use the information gained from these studies in translational research aimed at developing improved protection for those at risk and improved clinical outcomes for those who have been injured from a blast wave.

  15. Indoor propagation and assessment of blast waves from weapons using the alternative image theory

    NASA Astrophysics Data System (ADS)

    Kong, B.; Lee, K.; Lee, S.; Jung, S.; Song, K. H.

    2016-03-01

    Blast waves generated from the muzzles of various weapons might have significant effects on the human body, and these effects are recognized as being more severe when weapons are fired indoors. The risk can be assessed by various criteria, such as waveform, exposed energy, and model-based types. This study introduces a prediction model of blast wave propagation for estimating waveform parameters related to damage risk assessment. To simulate indoor multiple reflections in a simple way, the model is based on the alternative image theory and discrete wavefront method. The alternative theory is a kind of modified image theory, but it uses the image space concept from a receiver's perspective, so that it shows improved efficiency for indoor problems. Further, the discrete wavefront method interprets wave propagation as the forward movement of a finite number of wavefronts. Even though the predicted results show slight differences from the measured data, the locations of significant shock waves indicate a high degree of correlation between them. Since the disagreement results not from the proposed techniques but from the assumptions used, it is concluded that the model is appropriate for analysis of blast wave propagation in interior spaces.

  16. Magnetic Fields In Blast-wave-driven Instability Experiments Relevant To Supernova

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn; Drake, R.; Grosskopf, M.; Krauland, C.; Marion, D.; Fryxell, B.; Budde, A.; Remington, B.; Robey, H.; Hansen, J.; Miles, A.; Knauer, J.; Arnett, D.; Meakin, C.; Plewa, T.; Hearn, N.

    2009-05-01

    These experiments are scaled to the blast wave driven instabilities at the He/H interface during the explosion phase of SN1987A. This core-collapse supernova was detected about 50 kpc from Earth making it the first supernova observed so closely to earth in modern times. The progenitor star was a blue supergiant with a mass of 18-20 solar masses. A blast wave occurred following the supernova explosion because there was a sudden, finite release of energy. Blast waves consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 µm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses a three-dimensional interface with a wavelength of 71 µm in two orthogonal directions. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability. We have detected the interface structure under these conditions, using dual orthogonal radiography, and will show some of the resulting data. Recent advancements in our x-ray backlighting techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed. Current simulations do not show this phenomenon. It is possible that magnetic pressure generated by orthogonal components of the electron density gradient and the electron temperature gradient cause the spikes to reach the shock front. The amount of mass in the spike extensions is discussed. This research was sponsored by the SSAA through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064

  17. Relativistic blast-wave model for the rapid flux variations of AO 0235+164 and other compact radio sources

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.

    1978-01-01

    A relativistic blast-wave version of a signal-screen model is developed which can adequately explain the details of the flux-density and structural variations of compact extragalactic radio sources. The relativistic motion implied by flux variations is analyzed with respect to the synchrotron spectrum of the BL Lac object AO 0235+164 observed during outbursts, and a signal-screen model for rapidly expanding shells produced by ultrarelativistic blast waves is examined. The approximate observed structure of the blast wave at three stages in its evolution is illustrated, each stage is described, and the model is applied to the flux density outburst in AO 0235+164 observed in late 1975. The results show that a relativistic blast-wave model can in general reproduce the main features of the observed flux variations in compact sources. Some problems with the proposed model are briefly discussed.

  18. THE EARLY BLAST WAVE OF THE 2010 EXPLOSION OF U SCORPII

    SciTech Connect

    Drake, J. J.; Orlando, S.

    2010-09-10

    Three-dimensional hydrodynamic simulations exploring the first 18 hr of the 2010 January 28 outburst of the recurrent nova U Scorpii have been performed. Special emphasis was placed on capturing the enormous range in spatial scales in the blast. The pre-explosion system conditions included the secondary star and a flared accretion disk. These conditions can have a profound influence on the evolving blast wave. The blast itself is shadowed by the secondary star, which itself gives rise to a low-temperature bow shock. The accretion disk is completely destroyed in the explosion. A model with a disk gas density of 10{sup 15} cm{sup -3} produced a blast wave that is collimated and with clear bipolar structures, including a bipolar X-ray emitting shell. The degree of collimation depends on the initial mass of ejecta, energy of explosion, and circumstellar gas density distribution. It is most pronounced for a model with the lowest explosion energy (10{sup 43} erg) and mass of ejecta (10{sup -8} M {sub sun}). The X-ray luminosities of three of six models computed are close to, but consistent with, an upper limit to the early blast X-ray emission obtained by the Swift satellite, the X-ray luminosity being larger for higher circumstellar gas density and higher ejecta mass. The latter consideration, together with estimates of the blast energy from previous outbursts, suggests that the mass of ejecta in the 2010 outburst was not larger than 10{sup -7} M {sub sun}.

  19. Experimental determination of blast-wave pressure loading, thermal radiation protection, and electrical transmission loss for parabolic antenna models in simulated nuclear blast environments

    SciTech Connect

    George, J.H.

    1991-01-01

    A twelve-inch-diameter parabolic antenna model instrumented with eleven differential pressure sensors was tested at the Ballistics Research Laboratory, Aberdeen Proving Ground, Maryland. Transient pressure loading was determined for 37 different antenna model angular positions with respect to the direction of the blast wave at a peak overpressure of 3.0 pounds per square inch; limited data at 4.5 and 6.0 pounds per square inch were also investigated. The first millisecond of shock-wave interaction with the antenna features the most prominent fully reversed triangular pressure pulse. A blast function, F, was developed that accurately approximates the transient behavior of the blast wave resultant force and moment loading on the antenna model. The resultant blast force on the antenna model is minimized when the axis of the paraboloid of the model is rotated 82{degree} with respect to the direction of the blast wave. Four different thermal protective coatings were tested to evaluate the effects of coating color and thickness. Transmission-loss measurements were completed on eight different quartz-polyimide antenna models coated with Caapcoat and Ocean 477 thermal protective coatings.

  20. Adiabatic Transformation of Gravitational Stabilization Waves of the Crystalline Vacuum Space Into Baryons at the Big Bang

    NASA Astrophysics Data System (ADS)

    Montemayor-Aldrete, J. A.; Morones-Ibarra, J. R.; Morales-Mori, A.; Ugalde-Velez, P.; Mendoza-Allende, A.; Cabrera-Bravo, E.; Montemayor-Varela, A.

    2013-03-01

    It is shown that the entropy of the low density monochromatic gravitational waves which stabilize gravitationally the crystalline structure of vacuum cosmic space varies with the volume in the same way as the entropy of an ideal gas formed by particles. This implies that close enough to the local Big-Bang event the energy of all the gravitational waves which stabilizes the crystalline structure of vacuum space behaves thermodynamically as though it is consisted of a number of independent energy or matter quanta (neutrons). Also it is shown that the diminishing in the gravitational energy of the waves which stabilize the crystalline vacuum space structure is the source of energy required to produce the electromagnetic radiation which is responsible for the hot matter expansion through a preexisting infinite cosmic space. Matter and antimatter is produced in equal quantities at the Big Bang region and there are no annihilation events between them during their initial stage of expansion through vacuum cosmic space due to the gravitational stress gradient pattern existing around the source region which has zero gravitational stress all the matter travels globally in one direction (For instance pointing to the long range tension gravitational stress cell-region) and all the antimatter corresponding to the contiguous compressed cell-region travels in the opposite direction. The obtained expression for the volumetric electromagnetic energy density resembles the classical one proportional to , obtained for the black body radiation in equilibrium conditions at temperature ; and at thermal equilibrium with baryons for the decoupling temperature between photons and matter, , electromagnetic energy of radiation has a value of photons per baryon. Also the evaluation of the Gibbs ´s free energy for the adiabatic compression process of transformation of gravitational stabilization waves of the crystalline vacuum space into baryons at the Big Bang gives a value of zero for the

  1. Initiation of the Adiabatic Wave of Combustion for Obtaining the Substances with the Free Valence

    NASA Astrophysics Data System (ADS)

    Baideldonova, A.; Ksandopulo, G.; Mukhina, L.

    2016-04-01

    According to the task of obtaining substances with the free valence for the linkage of the nano-powders, the procedure of the synthesis of materials under the extreme nonequilibrium conditions is presented. The combustion of multilayer aluminothermic systems in the revolving reactor was investigated. Experiments were carried out in the reactor of high-temperature centrifuge. The initiation of process realizes by electric pulse in the effective layer. Further the wave of combustion was propagated along the axis of the reactor. The particles of the restored metal penetrated the underlayers of fresh mixture under the action of centrifugal acceleration and created the additional centers of ignition. The higher the density of metal, the higher speed and depth of penetration. An increase in the centrifugal acceleration strengthens the activity of process also. The speed of the motion of metallic particles grows. According the theoretical calculations it reaches 90 m/s in the case of tungsten.

  2. Blast wave loading pathways in heterogeneous material systems-experimental and numerical approaches.

    PubMed

    Selvan, Veera; Ganpule, Shailesh; Kleinschmit, Nick; Chandra, Namas

    2013-06-01

    Blast waves generated in the field explosions impinge on the head-brain complex and induce mechanical pressure pulses in the brain resulting in traumatic brain injury. Severity of the brain injury (mild to moderate to severe) is dependent upon the magnitude and duration of the pressure pulse, which in turn depends on the intensity and duration of the oncoming blast wave. A fluid-filled cylinder is idealized to represent the head-brain complex in its simplest form; the cylinder is experimentally subjected to an air blast of Friedlander type, and the temporal variations of cylinder surface pressures and strains and fluid pressures are measured. Based on these measured data and results from computational simulations, the mechanical loading pathways from the external blast to the pressure field in the fluid are identified; it is hypothesized that the net loading at a given material point in the fluid comprises direct transmissive loads and deflection-induced indirect loads. Parametric studies show that the acoustic impedance mismatches between the cylinder and the contained fluid as well as the flexural rigidity of the cylinder determine the shape/intensity of pressure pulses in the fluid. PMID:23699714

  3. The physical properties of the blast wave produced by a stoichiometric propane/oxygen explosion

    NASA Astrophysics Data System (ADS)

    Dewey, M. C.; Dewey, J. M.

    2014-07-01

    The trajectory of the primary shock produced by the explosion of a nominal 18.14 t (20 tn) hemispherical propane/oxygen charge was analysed previously to provide the physical properties immediately behind the shock, but gave no information about the time-resolved properties throughout the blast wave. The present study maps all the physical properties of the wave throughout and beyond the positive durations for a range of distances from about 1.6-18 m scaled to a 1 kg charge at NTP. The physical properties were calculated using a hydro-code to simulate the flow field produced by a spherical piston moving with a specific trajectory. This technique has been used extensively to determine the physical properties of blast waves from a variety of sources for which the piston path was determined by high-speed photography of smoke tracers established close to the charges immediately before detonation. In the case of the propane/oxygen explosion, smoke tracer data were not available to determine the trajectory of the spherical piston. An arbitrary piston path was used and its trajectory iteratively adjusted until it produced a blast wave with a primary shock whose trajectory exactly matched the measured trajectory from the propane/oxygen explosion. Throughout the studied flow field the time histories of hydrostatic pressure, density and particle velocity are well described by fits to the modified Friedlander equation. The properties are presented as functions of scaled radius and are compared with the properties of the blast wave from a 1 kg TNT surface burst explosion, and with other measurements of the same explosion.

  4. The physical properties of the blast wave produced by a stoichiometric propane/oxygen explosion

    NASA Astrophysics Data System (ADS)

    Dewey, M. C.; Dewey, J. M.

    2014-11-01

    The trajectory of the primary shock produced by the explosion of a nominal 18.14 t (20 tn) hemispherical propane/oxygen charge was analysed previously to provide the physical properties immediately behind the shock, but gave no information about the time-resolved properties throughout the blast wave. The present study maps all the physical properties of the wave throughout and beyond the positive durations for a range of distances from about 1.6-18 m scaled to a 1 kg charge at NTP. The physical properties were calculated using a hydro-code to simulate the flow field produced by a spherical piston moving with a specific trajectory. This technique has been used extensively to determine the physical properties of blast waves from a variety of sources for which the piston path was determined by high-speed photography of smoke tracers established close to the charges immediately before detonation. In the case of the propane/oxygen explosion, smoke tracer data were not available to determine the trajectory of the spherical piston. An arbitrary piston path was used and its trajectory iteratively adjusted until it produced a blast wave with a primary shock whose trajectory exactly matched the measured trajectory from the propane/oxygen explosion. Throughout the studied flow field the time histories of hydrostatic pressure, density and particle velocity are well described by fits to the modified Friedlander equation. The properties are presented as functions of scaled radius and are compared with the properties of the blast wave from a 1 kg TNT surface burst explosion, and with other measurements of the same explosion.

  5. Impulsive dispersion of a granular layer by a weak blast wave

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Saurel, R.; Jourdan, G.; Houas, L.

    2016-04-01

    The dispersion of particles by blast or shock waves induces the formation of coherent structures taking the shape of particle jets. In the present study, a blast wave, issued from an open shock tube, is generated at the center of a granular ring initially confined in a Hele-Shaw cell. With the present experimental setup, solid particle jet formation is clearly observed in a quasi-two-dimensional configuration. In all instances, the jets are initially generated inside the particle ring and thereafter expelled outward. Furthermore, thanks to the two-dimensional experimental configuration, a general study of the main parameters involved in these types of flows can be performed. Among them, the particle diameter, the density of the particles, the initial size of the ring, the shape of the overpressure generated and the surface friction of the Hele-Shaw cell are investigated. Empirical relationships are deduced from experimental results.

  6. Nonlinear growth of dynamical overstabilities in blast waves. [effects on supernova remnants

    NASA Technical Reports Server (NTRS)

    Mac Low, Mordecai-Mark; Norman, Michael L.

    1993-01-01

    The numerical gasdynamics code ZEUS-2D is used to directly model the dynamical overstabilities in blast waves. The linear analysis is confirmed by perturbing a blast wave with a low-amplitude eigenfunction of the overstability. The amplitude of the perturbations is increased in order to determine the nonlinear behavior of the overstabilities. The overstability is found to saturate due to weak transverse shocks in the shell. Transverse velocities in the dense shell reach the postshock sound speed, and high-density regions with sizes of the order of the shell thickness form. Transverse oscillations continue even after saturation. This confirms and explains the damping of the overstability experimentally discovered by Grun et al. (1991).

  7. On self-similar blast waves headed by the Chapman-Jouguet detonation.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Kuhl, A. L.; Kamel, M. M.

    1972-01-01

    Consideration of the whole class of self-similar solutions for blast waves bounded by Chapman-Jouguet detonations that propagate into a uniform, quiescent, zero counterpressure atmosphere of a perfect gas with constant specific heats. Since such conditions can be approached quite closely by some actual chemical systems at NTP, this raises the interesting possibility of the existence of Chapman-Jouguet detonations of variable velocity. The principal virtue of the results presented is, however, more of theoretical significance. They represent the limiting case for all the self-similar blast waves headed by gasdynamic discontinuities associated with a deposition of finite amounts of energy, and they exhibit some unique features owing to the singular nature of the Chapman-Jouguet condition.

  8. Simulation of the reflected blast wave from a C-4 charge

    NASA Astrophysics Data System (ADS)

    Howard, W. Michael; Kuhl, Allen L.; Tringe, Joseph

    2012-03-01

    The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 μm per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 7 ranges (GR = 0, 5.08, 10.16, 15.24, 20.32, 25.4, and 30.48 cm) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 5 cm), which were dominated by jetting effects.

  9. PARTICLE ACCELERATION IN THE EXPANDING BLAST WAVE OF {eta} CARINA'S GREAT ERUPTION OF 1843

    SciTech Connect

    Ohm, S.; Domainko, W.; Hinton, J. A. E-mail: wilfried.domainko@mpi-hd.mpg.d

    2010-08-01

    Non-thermal hard X-ray and high-energy (HE; 1 MeV {<=} E {<=} 100 GeV) {gamma}-ray emission in the direction of {eta} Carina has been recently detected using the INTEGRAL, AGILE, and Fermi satellites. So far this emission has been interpreted in the framework of particle acceleration in the colliding wind region between the two massive stars. However, the existence of a very fast moving blast wave which originates in the historical 1843 'Great Eruption' provides an alternative particle acceleration site in this system. Here, we explore an alternate scenario and find that inverse Compton emission from electrons accelerated in the blast wave can naturally explain both the flux and spectral shape of the measured hard X-ray and HE {gamma}-ray emission. This scenario is further supported by the lack of significant variability in the INTEGRAL and Fermi measured fluxes.

  10. Consistent dynamics of the components of an elliptically polarised wave with zero mean amplitudes in a nonlinear isotropic gyrotropic medium in the adiabatic approximation

    SciTech Connect

    Makarov, V A; Petnikova, V M; Rudenko, K V; Shuvalov, V V

    2015-01-31

    The adiabatic approximation is used to obtain an analytical solution to a nonintegrable problem of propagation of a plane elliptically polarised light wave with zero mean amplitudes of orthogonal circularly polarised field components through an isotropic gyrotropic medium with local and nonlocal components of Kerr nonlinearity and second-order group velocity dispersion. We describe the aperiodic evolution of bound (attributable to the medium nonlinearity) paired states, which are responsible for the propagation of two orthogonal polarisation components – cnoidal waves with significantly different periods. (nonlinear optical phenomena)

  11. Calculation of wing response to gusts and blast waves with vortex lift effect

    NASA Technical Reports Server (NTRS)

    Chao, D. C.; Lan, C. E.

    1983-01-01

    A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex-lattice method, unsteady suction analogy, and Pade approximate. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

  12. Calculation of wing response to gusts and blast waves with vortex lift effect

    NASA Technical Reports Server (NTRS)

    Chao, D. C.; Lan, C. E.

    1983-01-01

    A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex lattice method, unsteady suction analogy and Pade approximant. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

  13. Supernova blast waves in wind-blown bubbles, turbulent, and power-law ambient media

    NASA Astrophysics Data System (ADS)

    Haid, S.; Walch, S.; Naab, T.; Seifried, D.; Mackey, J.; Gatto, A.

    2016-08-01

    Supernova (SN) blast waves inject energy and momentum into the interstellar medium (ISM), control its turbulent multiphase structure and the launching of galactic outflows. Accurate modelling of the blast wave evolution is therefore essential for ISM and galaxy formation simulations. We present an efficient method to compute the input of momentum, thermal energy, and the velocity distribution of the shock-accelerated gas for ambient media (densities of 0.1 ≥ n0 [cm- 3] ≥ 100) with uniform (and with stellar wind blown bubbles), power-law, and turbulent (Mach numbers M from 1to100) density distributions. Assuming solar metallicity cooling, the blast wave evolution is followed to the beginning of the momentum conserving snowplough phase. The model recovers previous results for uniform ambient media. The momentum injection in wind-blown bubbles depend on the swept-up mass and the efficiency of cooling, when the blast wave hits the wind shell. For power-law density distributions with n(r) ˜ r-2 (for n(r) > nfloor) the amount of momentum injection is solely regulated by the background density nfloor and compares to nuni = nfloor. However, in turbulent ambient media with lognormal density distributions the momentum input can increase by a factor of 2 (compared to the homogeneous case) for high Mach numbers. The average momentum boost can be approximated as p_{turb}/{p_{{0}}} =23.07 (n_{{0,turb}}/1 cm^{-3})^{-0.12} + 0.82 (ln (1+b2{M}2))^{1.49}(n_{{0,turb}}/1 cm^{-3})^{-1.6}. The velocity distributions are broad as gas can be accelerated to high velocities in low-density channels. The model values agree with results from recent, computationally expensive, three-dimensional simulations of SN explosions in turbulent media.

  14. Calculation of wing response to gusts and blast waves with vortex lift effect

    SciTech Connect

    Chao, D.C.; Lan, C.E.

    1983-04-01

    A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex lattice method, unsteady suction analogy and Pade approximant. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

  15. Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2013-09-01

    Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ηbw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

  16. NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

    SciTech Connect

    Gat, Ilana; Van Eerten, Hendrik; MacFadyen, Andrew

    2013-08-10

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

  17. A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

    PubMed Central

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is

  18. A parametric approach to shape field-relevant blast wave profiles in compressed-gas-driven shock tube.

    PubMed

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1-3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68-1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is compared

  19. Macro-mechanical modelling of blast wave mitigation in foams. Part I: review of available experiments and models

    NASA Astrophysics Data System (ADS)

    Britan, A.; Shapiro, H.; Liverts, M.; Ben-Dor, G.; Chinnayya, A.; Hadjadj, A.

    2013-02-01

    Multiphase flows, which involve compressible or incompressible fluids with linear or nonlinear dynamics, are found in all areas of technology at all length scales and flow regimes. In this contribution, we discuss application of aqueous-foam barriers against blast wave impact. The first experiments demonstrating this behaviour were conducted in the early 1980s in free-field tests. Based on structural requirements, various foams with different blast energy contents were tested with the aim of characterizing the time history of the blast pressure reduction. A number of consistent methodologies for calculating this pressure reduction in foam are based on the effective gas flow model. For estimating the uncertainties of these methodologies, we briefly demonstrate their comparison with existing experimental data. Thereafter, we present various modifications of modelling approaches and their comparison with new results of blast wave experiments.

  20. Application of blast wave theory to explosive propulsion. [system performance analysis

    NASA Technical Reports Server (NTRS)

    Back, L. H.

    1975-01-01

    An analysis was carried out by using blast wave theory to delineate the important aspects of detonating explosives in nozzles, such as flow and wave phenomena, characteristic length and time scales, and the parameters on which the specific impulse is dependent. The propulsive system utilizes the momentum of the ambient gas set into motion in the nozzle by the explosion. A somewhat simplified model was considered for the situation where the mass of ambient gas in the nozzle is much greater than the mass of gas produced in the explosion, a condition of interest for dense atmospheres, e.g., near the surface of Venus. Instantaneous detonation and energy release was presumed to occur at the apex of a conical nozzle, and the shock wave generated by the explosion was taken to propagate as a spherical wave, thereby setting the ambient gas in the nozzle into one-dimensional radially outward motion.

  1. Spatially and temporally resolved temperature and shock-speed measurements behind a laser-induced blast wave of energetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Roy, Sukesh; Jiang, Naibo; Stauffer, Hans U.; Schmidt, Jacob B.; Kulatilaka, Waruna D.; Meyer, Terrence R.; Bunker, Christopher E.; Gord, James R.

    2013-05-01

    Spatially and temporally resolved temperature measurements behind an expanding blast wave are made using picosecond (ps) N2 coherent anti-Stokes Raman scattering (CARS) following laser flash heating of mixtures containing aluminum nanoparticles embedded in ammonium-nitrate oxidant. Production-front ps-CARS temperatures as high as 3600 ± 180 K—obtained for 50-nm-diameter commercially produced aluminum-nanoparticle samples—are observed. Time-resolved shadowgraph images of the evolving blast waves are also obtained to determine the shock-wave position and corresponding velocity. These results are compared with near-field blast-wave theory to extract relative rates of energy release for various particle diameters and passivating-layer compositions.

  2. Kinetics of blast waves in one-dimensional conservative and dissipative gases

    NASA Astrophysics Data System (ADS)

    Barbier, Matthieu

    2015-11-01

    Blast waves caused by a localized release of energy in a gas have become a textbook hydrodynamics problem since the seminal works of Taylor, von Neumann and Sedov. However, the topic has received very little attention at the kinetic level, which can provide a complementary range of insights: notably, transient regimes and the microscopic structure of the shock front, reduced to a singular boundary in continuum equations. As a first step, we study blast waves in a one-dimensional gas of hard particles. This simple limit helps develop important intuitions pertaining to any type of blast, and it is amenable to kinetic analysis—even with the addition of energy dissipation leading to ‘snowplow’ dynamics, or an inhomogeneous mass repartition (as found in astrophysical systems and granular materials). Furthermore, the conservative case proves to be of remarkable interest in demonstrating subtle aspects of dimensional analysis and their resolution through microscopic insights. We show that it can effectively behave like a zero-dimensional system, reduced to the shock front, depending on whether a length scale appears in the initial mass distribution.

  3. Biological effects of weak blast waves and safety limits for internal organ injury in the human body.

    PubMed

    Yang, Z; Wang, Z; Tang, C; Ying, Y

    1996-03-01

    One hundred and seventeen adult sheep of both sexes, each weighing 15.2-42.4 kg, were used for this study. The purpose of this study was to investigate the relationship of the physical parameters of the waves to internal organ injury by exposing sheep to weak blast waves in TNT (trinitrotoluene) explosions, biological shock tube, and gun muzzle blasts. The results showed that the organ most sensitive to the TNT explosion was the lungs, whereas the upper respiratory tract was most sensitive to muzzle blast waves. The injury thresholds of overpressure were 29.0, 29.5, and 41.2 kPa for upper respiratory tract, lungs, and gastrointestinal tract respectively at a single exposure. Repeated exposure to 60 blasts reduced the injury threshold of the internal organs. The injury thresholds for upper respiratory tract, lungs, and gastrointestinal tract were 21.0, 18.0, and 40.4 kPa, respectively. The duration of overpressure of weak blast waves was 2.4-4.2 milliseconds, which did not significantly affect the severity of injury. The safety limits of weak blast waves to internal organ injury of human body were as follows: Ps = 37-3Ln.Tc.N/4(Tc.N < or = 1000) and Ps = 20.4(Tc.N > 1000). The results suggest that repeated exposures decrease the injury threshold of the internal organs. The safety limits proposed could protect 90% of the exposed population against internal organ injury caused by weak blast waves. PMID:8606431

  4. Examination of the protective roles of helmet/faceshield and directionality for human head under blast waves.

    PubMed

    Sarvghad-Moghaddam, Hesam; Jazi, Mehdi Salimi; Rezaei, Asghar; Karami, Ghodrat; Ziejewski, Mariusz

    2015-01-01

    A parametric study was conducted to delineate the efficacy of personal protective equipment (PPE), such as ballistic faceshields and advanced combat helmets, in the case of a blast. The propagations of blast waves and their interactions with an unprotected head, a helmeted one, and a fully protected finite element head model (FEHM) were modeled. The biomechanical parameters of the brain were recorded when the FEHM was exposed to shockwaves from the front, back, top, and bottom. The directional dependent tissue response of the brain and the variable efficiency of PPE with respect to the blast orientation were two major results of this study. PMID:25413615

  5. Low-cost rapid miniature optical pressure sensors for blast wave measurements.

    PubMed

    Wu, Nan; Wang, Wenhui; Tian, Ye; Zou, Xiaotian; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

    2011-05-23

    This paper presents an optical pressure sensor based on a Fabry-Perot (FP) interferometer formed by a 45° angle polished single mode fiber and an external silicon nitride diaphragm. The sensor is comprised of two V-shape grooves with different widths on a silicon chip, a silicon nitride diaphragm released on the surface of the wider V-groove, and a 45° angle polished single mode fiber. The sensor is especially suitable for blast wave measurements: its compact structure ensures a high spatial resolution; its thin diaphragm based design and the optical demodulation scheme allow a fast response to the rapid changing signals experienced during blast events. The sensor shows linearity with the correlation coefficient of 0.9999 as well as a hysteresis of less than 0.3%. The shock tube test demonstrated that the sensor has a rise time of less than 2 µs from 0 kPa to 140 kPa. PMID:21643336

  6. A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

    NASA Astrophysics Data System (ADS)

    Park, Dohyun; Jeon, Byungkyu; Jeon, Seokwon

    2009-06-01

    Blasting is often a necessary part of mining and construction operations, and is the most cost-effective way to break rock, but blasting generates both noise and ground vibration. In urban areas, noise and vibration have an environmental impact, and cause structural damage to nearby structures. Various wave-screening methods have been used for many years to reduce blast-induced ground vibration. However, these methods have not been quantitatively studied for their reduction effect of ground vibration. The present study focused on the quantitative assessment of the effectiveness in vibration reduction of line-drilling as a screening method using a numerical method. Two numerical methods were used to analyze the reduction effect toward ground vibration, namely, the “distinct element method” and the “non-linear hydrocode.” The distinct element method, by particle flow code in two dimensions (PFC 2D), was used for two-dimensional parametric analyses, and some cases of two-dimensional analyses were analyzed three-dimensionally using AUTODYN 3D, the program of the non-linear hydrocode. To analyze the screening effectiveness of line-drilling, parametric analyses were carried out under various conditions, with the spacing, diameter of drill holes, distance between the blasthole and line-drilling, and the number of rows of drill holes, including their arrangement, used as parameters. The screening effectiveness was assessed via a comparison of the vibration amplitude between cases both with and without screening. Also, the frequency distribution of ground motion of the two cases was investigated through fast Fourier transform (FFT), with the differences also examined. From our study, it was concluded that line-drilling as a screening method of blast-induced waves was considerably effective under certain design conditions. The design details for field application have also been proposed.

  7. Blast-Associated Shock Waves Result in Increased Brain Vascular Leakage and Elevated ROS Levels in a Rat Model of Traumatic Brain Injury

    PubMed Central

    Petro, Marianne; Dudzinski, Dave; Stewart, Desiree; Courtney, Amy; Courtney, Michael; Labhasetwar, Vinod

    2015-01-01

    Blast-associated shock wave-induced traumatic brain injury (bTBI) remains a persistent risk for armed forces worldwide, yet its detailed pathophysiology remains to be fully investigated. In this study, we have designed and characterized a laboratory-scale shock tube to develop a rodent model of bTBI. Our blast tube, driven by a mixture of oxygen and acetylene, effectively generates blast overpressures of 20–130 psi, with pressure-time profiles similar to those of free-field blast waves. We tested our shock tube for brain injury response to various blast wave conditions in rats. The results show that blast waves cause diffuse vascular brain damage, as determined using a sensitive optical imaging method based on the fluorescence signal of Evans Blue dye extravasation developed in our laboratory. Vascular leakage increased with increasing blast overpressures and mapping of the brain slices for optical signal intensity indicated nonhomogeneous damage to the cerebral vasculature. We confirmed vascular leakage due to disruption in the blood-brain barrier (BBB) integrity following blast exposure. Reactive oxygen species (ROS) levels in the brain also increased with increasing blast pressures and with time post-blast wave exposure. Immunohistochemical analysis of the brain sections analyzed at different time points post blast exposure demonstrated astrocytosis and cell apoptosis, confirming sustained neuronal injury response. The main advantages of our shock-tube design are minimal jet effect and no requirement for specialized equipment or facilities, and effectively generate blast-associated shock waves that are relevant to battle-field conditions. Overall data suggest that increased oxidative stress and BBB disruption could be the crucial factors in the propagation and spread of neuronal degeneration following blast injury. Further studies are required to determine the interplay between increased ROS activity and BBB disruption to develop effective therapeutic

  8. Blast-Associated Shock Waves Result in Increased Brain Vascular Leakage and Elevated ROS Levels in a Rat Model of Traumatic Brain Injury.

    PubMed

    Kabu, Shushi; Jaffer, Hayder; Petro, Marianne; Dudzinski, Dave; Stewart, Desiree; Courtney, Amy; Courtney, Michael; Labhasetwar, Vinod

    2015-01-01

    Blast-associated shock wave-induced traumatic brain injury (bTBI) remains a persistent risk for armed forces worldwide, yet its detailed pathophysiology remains to be fully investigated. In this study, we have designed and characterized a laboratory-scale shock tube to develop a rodent model of bTBI. Our blast tube, driven by a mixture of oxygen and acetylene, effectively generates blast overpressures of 20-130 psi, with pressure-time profiles similar to those of free-field blast waves. We tested our shock tube for brain injury response to various blast wave conditions in rats. The results show that blast waves cause diffuse vascular brain damage, as determined using a sensitive optical imaging method based on the fluorescence signal of Evans Blue dye extravasation developed in our laboratory. Vascular leakage increased with increasing blast overpressures and mapping of the brain slices for optical signal intensity indicated nonhomogeneous damage to the cerebral vasculature. We confirmed vascular leakage due to disruption in the blood-brain barrier (BBB) integrity following blast exposure. Reactive oxygen species (ROS) levels in the brain also increased with increasing blast pressures and with time post-blast wave exposure. Immunohistochemical analysis of the brain sections analyzed at different time points post blast exposure demonstrated astrocytosis and cell apoptosis, confirming sustained neuronal injury response. The main advantages of our shock-tube design are minimal jet effect and no requirement for specialized equipment or facilities, and effectively generate blast-associated shock waves that are relevant to battle-field conditions. Overall data suggest that increased oxidative stress and BBB disruption could be the crucial factors in the propagation and spread of neuronal degeneration following blast injury. Further studies are required to determine the interplay between increased ROS activity and BBB disruption to develop effective therapeutic strategies

  9. The soft X-ray background as a supernova blast wave viewed from inside: Solar abundance models

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.

    1984-01-01

    A model of the soft X-ray background is presented in which the Sun is assumed to be inside an active supernova blast wave. The blast wave evolves in a preexisting cavity. The broad band surface brightnesses is explained by such a blast wave with an explosion energy of E sub approx. 5 x 10 to the 50th power ergs and radius 80 to 100 pc, using solar abundances. An approach to treating the problem of large anisotropies in the ambient medium is also explored, accommodating the observed anticorrelation between the soft X-ray surface brightness and the 21 cm column density. It is found that only for post shock temperatures below 10 6 K a shock propagating into a density enhancement will be dimmer than a similar shock in a lower density region.

  10. The soft X-ray background as a supernova blast wave viewed from inside - Solar abundance models

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.

    1986-01-01

    A model of the soft X-ray background is presented in which the sun is assumed to be inside an active supernova blast wave. The blast wave evolves in a preexisting cavity. The broad band surface brightnesses is explained by such a blast wave with an explosion energy of E sub approximately 5 x 10 to the 50th power ergs and radius 80 to 100 pc, using solar abundances. An approach to treating the problem of large anisotropies in the ambient medium is also explored, accommodating the observed anticorrelation between the soft X-ray surface brightness and the 21 cm column density. It is found that only for post shock temperatures below 10 to the 6 power K a shock propagating into a density enhancement will be dimmer than a similar shock in a lower density region.

  11. Collimation and Asymmetry of the Hot Blast Wave from the Recurrent Nova V745 Sco

    NASA Astrophysics Data System (ADS)

    Drake, Jeremy J.; Delgado, Laura; Laming, J. Martin; Starrfield, Sumner; Kashyap, Vinay; Orlando, Salvatore; Page, Kim L.; Hernanz, M.; Ness, J.-U.; Gehrz, R. D.; van Rossum, Daan; Woodward, Charles E.

    2016-07-01

    The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 107 K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s-1, an FWHM of 1200 ± 30 km s-1, and an average net blueshift of 165 ± 10 km s-1. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 1043 erg and confirms an ejected mass of approximately 10-7 M ⊙. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.

  12. Collimation and Asymmetry of the Hot Blast Wave from the Recurrent Nova V745 Sco

    NASA Astrophysics Data System (ADS)

    Drake, Jeremy J.; Delgado, Laura; Laming, J. Martin; Starrfield, Sumner; Kashyap, Vinay; Orlando, Salvatore; Page, Kim L.; Hernanz, M.; Ness, J.-U.; Gehrz, R. D.; van Rossum, Daan; Woodward, Charles E.

    2016-07-01

    The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 107 K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s‑1, an FWHM of 1200 ± 30 km s‑1, and an average net blueshift of 165 ± 10 km s‑1. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 1043 erg and confirms an ejected mass of approximately 10‑7 M ⊙. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.

  13. The Blast-Wave-Driven Instability as a Vehicle for Understanding Supernova Explosion Structure

    SciTech Connect

    Miles, A R

    2008-05-27

    Blast-wave-driven instabilities play a rich and varied role throughout the evolution of supernovae from explosion to remnant, but interpreting their role is difficult due to the enormous complexity of the stellar systems. We consider the simpler and fundamental hydrodynamic instability problem of a material interface between two constant-density fluids perturbed from spherical and driven by a divergent central Taylor-Sedov blast wave. The existence of unified solutions at high Mach number and small density ratio suggests that general conclusions can be drawn about the likely asymptotic structure of the mixing zone. To this end we apply buoyancy-drag and bubble merger models modified to include the effects of divergence and radial velocity gradients. In general, these effects preclude the true self-similar evolution of classical Raleigh-Taylor, but can be incorporated into a quasi-self-similar growth picture. Loss of memory of initial conditions can occur in the quasi-self-similar model, but requires initial mode numbers higher than those predicted for pre-explosion interfaces in Type II SNe, suggesting that their late-time structure is likely strongly influenced by details of the initial perturbations. Where low-modes are dominant, as in the Type Ia Tycho remnant, they result from initial perturbations rather than generation from smaller scales. Therefore, structure observed now contains direct information about the explosion process. When large-amplitude modes are present in the initial conditions, the contribution to the perturbation growth from the Richtmyer-Meshkov instability is significant or dominant compared to Rayleigh-Taylor. Such Richtmyer-Meshkov growth can yield proximity of the forward shock to the growing spikes and structure that strongly resembles that observed in the Tycho. Laser-driven high-energy-density laboratory experiments offer a promising avenue for testing model and simulation descriptions of blast-wave-driven instabilities and making

  14. Modeling and simulation of blast-induced, early-time intracranial wave physics leading to traumatic brain injury.

    SciTech Connect

    Ford, Corey C.; Taylor, Paul Allen

    2008-02-01

    The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm{sup 3} voxels), 5 material model of the human head was created by segmentation of color cryosections from the Visible Human Female dataset. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior and lateral directions. Three dimensional plots of maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric (shear) stress within the first 2 milliseconds of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 msec time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI.

  15. Biomechanical assessment of brain dynamic responses due to blast pressure waves.

    PubMed

    Chafi, M S; Karami, G; Ziejewski, M

    2010-02-01

    A mechanized and integrated computational scheme is introduced to determine the human brain responses in an environment where the human head is exposed to explosions from trinitrotoluene (TNT), or other high-yield explosives, in military applications. The procedure is based on a three-dimensional (3-D) non-linear finite element method (FEM) that implements a simultaneous conduction of explosive detonation, shock wave propagation, blast-head interactions, and the confronting human head. The processes of blast propagation in the air and blast interaction with the head are modeled by an Arbitrary Lagrangian-Eulerian (ALE) multi-material FEM formulation, together with a penalty-based fluid/structure interaction (FSI) algorithm. Such a model has already been successfully validated against experimental data regarding air-free blast and plate-blast interactions. The human head model is a 3-D geometrically realistic configuration that has been previously validated against the brain intracranial pressure (ICP), as well as shear and principal strains under different impact loadings of cadaveric experimental tests of Hardy et al. [Hardy W. N., C. Foster, M. Mason, S. Chirag, J. Bishop, M. Bey, W. Anderst, and S. Tashman. A study of the response of the human cadaver head to impact. Proc. 51 ( st ) Stapp. Car Crash J. 17-80, 2007]. Different scenarios have been assumed to capture an appropriate picture of the brain response at a constant stand-off distance of nearly 80 cm from the core of the explosion, but exposed to different amounts of a highly explosive (HE) material such as TNT. The over-pressures at the vicinity of the head are in the range of about 2.4-8.7 atmosphere (atm), considering the reflected pressure from the head. The methodology provides brain ICP, maximum shear stresses and maximum principal strain within the milli-scale time frame of this highly dynamic phenomenon. While focusing on the two mechanical parameters of pressure, and also on the maximum shear

  16. Mathematical theory of cylindrical isothermal blast waves in a magnetic field. [with application to supernova remnant evolution

    NASA Technical Reports Server (NTRS)

    Lerche, I.

    1981-01-01

    An analysis is conducted regarding the properties of cylindrically symmetric self-similar blast waves propagating away from a line source into a medium whose density and magnetic field (with components in both the phi and z directions) both vary as r to the -(omega) power (with omega less than 1) ahead of the blast wave. The main results of the analysis can be divided into two classes, related to a zero azimuthal field and a zero longitudinal field. In the case of the zero longitudinal field it is found that there are no physically acceptable solutions with continuous postshock variations of flow speed and gas density.

  17. Blast wave in a nozzle for propulsive applications

    NASA Technical Reports Server (NTRS)

    Varsi, G.; Back, L. H.; Kim, K.

    1976-01-01

    The reported investigation has been conducted in connection with studies concerning the development of a propulsion system based on the use of a detonating fluid propellant. Measurements have been made of the pressure and shock wave velocity in a conical nozzle at various ambient pressures and at an ambient temperature of 25 C. In the experiments a small amount of explosive was placed at the end wall of a conical aluminum nozzle and detonated by a microdetonator inside the nozzle. Differences regarding the characteristics of conventional chemical propulsion and detonation propulsion are illustrated with the aid of a graph. One- and two-dimensional numerical flow calculations were performed and compared with the experimental data.

  18. Laboratory observation of secondary shock formation ahead of a strongly radiative blast wave

    SciTech Connect

    Hansen, J F; Edwards, M J; Froula, D H; Gregori, G; Edens, A; Ditmire, T

    2005-11-16

    High Mach number blast waves were created by focusing a laser pulse on a solid pin, surrounded by nitrogen or xenon gas. In xenon, the initial shock is strongly radiative, sending out a supersonic radiative heat wave far ahead of itself. The shock propagates into the heated gas, diminishing in strength as it goes. The radiative heat wave also slows, and when its Mach number drops to 2 with respect to the downstream plasma, the heat wave drives a second shock ahead of itself to satisfy mass and momentum conservation in the heat wave reference frame; the heat wave becomes subsonic behind the second shock. For some time both shocks are observed simultaneously. Eventually the initial shock dimimishes in strength so much that it can longer be observed, but the second shock continues to propagate long after this time. This sequence of events is a new phenomenon that has not previously been discussed in literature. Numerical simulation clarifies the origin of the second shock, and its position is consistent with an analytical estimate.

  19. Non-planar ion-acoustic solitary waves and their head-on collision in a plasma with nonthermal electrons and warm adiabatic ions

    SciTech Connect

    Han Jiuning; He Yonglin; Chen Yan; Zhang Kezhi; Ma Baohong

    2013-01-15

    By using the model of Cairns et al.[Geophys. Rev. Lett. 22, 2709 (1995)], the head-on collision of cylindrical/spherical ion-acoustic solitary waves in an unmagnetized non-planar plasma consisting of warm adiabatic ions and nonthermally distributed electrons is investigated. The extended Poincare-Lighthill-Kuo perturbation method is used to derive the modified Korteweg-de Vries equations for ion-acoustic solitary waves in this plasma system. The effects of the plasma geometry m, the ion to electron temperature ratio {sigma}, and the nonthermality of the electron distribution {alpha} on the interaction of the colliding solitary waves are studied. It is found that the plasma geometries have a big impact on the phase shifts of solitary waves. Also it is important to note that the phase shifts induced by the collision of compressive and rarefactive solitary waves are very different. We point out that this study is useful to the investigations about the observations of electrostatic solitary structures in astrophysical as well as in experimental plasmas with nonthermal energetic electrons.

  20. Self-generated Magnetic Fields in Blast-wave Driven Rayleigh-Taylor Experiments

    NASA Astrophysics Data System (ADS)

    Flaig, Markus; Plewa, Tomasz

    2014-10-01

    We study the generation of magnetic fields via the Biermann battery effect in blast-wave driven Rayleigh-Taylor experiments. Previous estimates have shown that in a typical experiment, one should expect fields in the MG range to be generated, with the potential to influence the Rayleigh-Taylor morphology. We perform two- and three-dimensional numerical simulations, where we solve the extended set of MHD equations known as the Braginskii equations. The simulation parameters reflect the physical conditions in past experiments performed on the OMEGA laser and potential future experiments on the NIF laser facility. When neglecting the friction force between electrons and ions in the simulations, magnetic fields of the order of a few 0.1 MG (with a plasma smaller than 1000) are generated, and are found to be dynamically significant. However, it turns out that once the friction force is included, the magnetic fields become much smaller (with a plasma beta greater than 100000) which have negligible influence on the dynamics of the system. Our results therefore indicate that, contrary to previous speculations, it is highly unlikely that self-generated magnetic fields can influence the morphology of a typical blast-wave driven Rayleigh-Taylor experiment. M.F. and T.P. were supported by the DOE Grant DE-FG52- 09NA29548 and the NSF Grant AST-1109113. This research used resources of the National Energy Re.

  1. Interaction and coalescence of multiple simultaneous and non-simultaneous blast waves

    NASA Astrophysics Data System (ADS)

    Qiu, S.; Eliasson, V.

    2016-05-01

    Interaction of multiple blast waves can be used to direct energy toward a target while simultaneously reducing collateral damage away from the target area. In this paper, simulations of multiple point source explosives were performed and the resulting shock interaction and coalescence behavior were explored. Three to ten munitions were placed concentrically around the target, and conditions at the target area were monitored and compared to those obtained using a single munition. For each simulation, the energy summed over all munitions was kept constant, while the radial distances between target and munitions and the munition initiation times were varied. Each munition was modeled as a point source explosion. The resulting blast wave propagation and shock front coalescence were solved using the inviscid Euler equations of gas dynamics on overlapping grids employing a finite difference scheme. Results show that multiple munitions can be beneficial for creating extreme conditions at the intended target area; over 20 times higher peak pressure is obtained for ten simultaneous munitions compared to a single munition. Moreover, peak pressure at a point away from the target area is reduced by more than a factor of three.

  2. GAMMA-RAY BURST AFTERGLOW SCALING RELATIONS FOR THE FULL BLAST WAVE EVOLUTION

    SciTech Connect

    Van Eerten, Hendrik J.; MacFadyen, Andrew I.

    2012-03-10

    We demonstrate that gamma-ray burst afterglow spectra and light curves can be calculated for arbitrary explosion and radiation parameters by scaling the peak flux and the critical frequencies connecting different spectral regimes. Only one baseline calculation needs to be done for each jet opening angle and observer angle. These calculations are done numerically using high-resolution relativistic hydrodynamical afterglow blast wave simulations which include the two-dimensional dynamical features of expanding and decelerating afterglow blast waves. Any light curve can then be generated by applying scaling relations to the baseline calculations. As a result, it is now possible to fully fit for the shape of the jet break, e.g., at early-time X-ray and optical frequencies. In addition, late-time radio calorimetry can be improved since the general shape of the transition into the Sedov-Taylor regime is now known for arbitrary explosion parameters so the exact moment when the Sedov-Taylor asymptote is reached in the light curve is no longer relevant. When calculating the baselines, we find that the synchrotron critical frequency {nu}{sub m} and the cooling break frequency {nu}{sub c} are strongly affected by the jet break. The {nu}{sub m} temporal slope quickly drops to the steep late-time Sedov-Taylor slope, while the cooling break {nu}{sub c} first steepens and then rises to meet the level of its shallow late-time asymptote.

  3. Ultra-high-energy cosmic ray acceleration by relativistic blast waves

    NASA Astrophysics Data System (ADS)

    Gallant, Yves A.; Achterberg, Abraham

    1999-05-01

    We consider the acceleration of charged particles at the ultrarelativistic shocks, with Lorentz factors Gamma_s>>1 relative to the upstream medium, arising in relativistic fireball models of gamma-ray bursts (GRBs). We show that for Fermi-type shock acceleration, particles initially isotropic in the upstream medium can gain a factor of order Gamma_s^2 in energy in the first shock-crossing cycle, but that the energy gain factor for subsequent shock-crossing cycles is only of order 2, because for realistic deflection processes particles do not have time to become isotropic upstream before recrossing the shock. We evaluate the maximum energy attainable and the efficiency of this process, and show that for a GRB fireball expanding into a typical interstellar medium, these exclude the production of ultra-high-energy cosmic rays (UHECRs), with energies in the range 10^18.5-10^20.5 eV, by the blast wave. However, we propose that in the context of neutron-star binaries as the progenitors of GRBs, relativistic ions from the pulsar-wind bubbles produced by these systems could be accelerated by the blast wave. We show that if the known binary pulsars are typical, the maximum energy, efficiency, and spectrum in this case can account for the observed population of UHECRs.

  4. Three-dimensional simulations of solar granulation and blast wave using ZEUS-MP code

    NASA Astrophysics Data System (ADS)

    Nurzaman, M. Z.; Herdiwijaya, D.

    2015-09-01

    Sun is nearest and the only star that can be observed in full disk mode. Meanwhile other stars simply can be observed as dot and cannot be seen in full disk like the Sun. Due to this condition, detail events in the Sun can possibly observable. For example, flare, prominence, granulation and other features can be seen easily compared to other stars. In other word the observational data can be obtained easily. And for better understanding, computational simulation is needed too. In this paper we use ZEUS-MP, a numerical code for the simulation of fluid dynamical flows in astrophysics, to study granulation and blast wave in the Sun. ZEUS-MP allows users to use hydrodynamic (HD) or magneto hydrodynamic (MHD) simulations singly or in concert, in one, two, or three space dimensions. For granulation case, we assume that there is no influence from magnetic field. So, it's enough to just use HD simulations. Physical parameters were analyzed for this case is velocity and density. The result shows that velocity as time function indicated more complex pattern than density. For blast wave case, we use it to study one of the Sun energetic event namely Coronal Mass Ejections (CMEs). In this case, we cannot ignore influence from magnetic field. So we use MHD simulations. Physical parameters were analyzed for this case is velocity and energy. The result shows more complex pattern for both parameters. It is shown too as if they have opposite pattern. When energy is high, velocity is not too fast, conversely.

  5. Accelerated dynamics of blast wave driven Rayleigh-Taylor instabilities in high energy density plasmas

    NASA Astrophysics Data System (ADS)

    Swisher, N.; Kuranz, C.; Drake, R. P.; Abarzhi, S. I.

    2014-10-01

    We report the systematic analysis of experimental data describing the late time evolution of the high Mach number and high Reynolds number Rayleigh-Taylor instability which is driven by a blast wave. The parameter regime is relevant to high energy density plasmas and astrophysics. The experiments have been conducted at the Omega laser facility. By processing the experimental x-ray images, we quantified the delicate features of RT dynamics, including the measurements of the curvature of the transmitted shock and the interface envelopes, the positions of RT bubbles and spikes, and the quantification of statistics of RT mixing. The measurements were performed at four time steps and for three different initial perturbations of the target (single mode and two two-mode). We found that within the noise level the curvatures of the shock and interface envelope evolve steadily and are an imprint of laser imperfections. At late times, the bubble merge does not occur, and the flow keeps significant degree of order. Yet, the blast-wave-driven RT spikes do accelerate with the power-law exponent smaller than that in case of sustained acceleration. We compared the experimental results with the momentum model of RT mixing and stochastic model achieving good agreement. The work is supported by the US National Science Foundation.

  6. VISAR Unfold Analysis of MagLIF Laser Blast Wave Experiments

    NASA Astrophysics Data System (ADS)

    Hess, Mark; Peterson, Kyle; Harvey-Thompson, Adam

    2015-06-01

    MagLIF (Magnetized Liner Inertial Fusion) is a fusion energy scheme, which utilizes a short laser pulse to preheat a fuel, and a magnetically driven cylindrical liner to compress the fuel to high energy density plasma conditions. Recently, a set of successful experiments have been performed to evaluate the effectiveness of our preheat process in MagLIF using the Z-Beamlet laser at Sandia. The fuel is preheated in the liner, with no compression from the Z-machine, and a VISAR diagnostic was fielded on the outer surface of the liner to measure velocity of the liner due to the pressure of the laser blast wave on the inner surface of the liner. In support of this program, we developed a fast unfold method of the VISAR data using semi-analytical techniques/numerical methods. The method incorporates appropriate boundary conditions at both edges of the VISAR foil, realistic EOS tables, and an additional pressure pulse time-delay feature for accurately unfolding the time-dependent pressure from the VISAR data. Our fully automated method can produce high-quality unfolds of the laser blast wave in under a minute. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE-AC04-94AL85000.

  7. The Half Wave Plate Rotator for the BLAST-TNG Balloon-Borne Telescope

    NASA Astrophysics Data System (ADS)

    Setiawan, Hananiel; Ashton, Peter; Novak, Giles; Angilè, Francesco E.; Devlin, Mark J.; Galitzki, Nicholas; Ade, Peter; Doyle, Simon; Pascale, Enzo; Pisano, Giampaolo; Tucker, Carole E.

    2016-01-01

    The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG) is an experiment designed to map magnetic fields in molecular clouds in order to study their role in the star formation process. The telescope will be launched aboard a high-altitude balloon in December 2016 for a 4-week flight from McMurdo station in Antarctica. BLAST-TNG will measure the polarization of submillimeter thermal emission from magnetically aligned interstellar dust grains, using large format arrays of kinetic inductance detectors operating in three bands centered at 250, 350, and 500 microns, with sub-arcminute angular resolution. The optical system includes an achromatic Half Wave Plate (HWP), mounted in a Half Wave Plate rotator (HWPr). The HWP and HWPr will operate at 4 K temperature to reduce thermal noise in our measurements, so it was crucial to account for the effects of thermal contraction at low temperature in the HWPr design. It was also equally important for the design to meet torque requirements while minimizing the power from friction and conduction dissipated at the 4 K stage. We also discuss our plan for cold testing the HWPr using a repurposed cryostat with a Silicon Diode thermometer read out by an EDAS-CE Ethernet data acquisition system.

  8. Spatially-resolved x-ray scattering measurements of a planar blast wave

    NASA Astrophysics Data System (ADS)

    Gamboa, E. J.; Montgomery, D. S.; Benage, J. F.; Falk, K.; Kuranz, C. C.; Keiter, P. A.; Drake, R. P.

    2012-10-01

    In many laboratory astrophysics experiments, intense laser irradiation creates novel material conditions with large, one-dimensional gradients in the temperature, density, and ionization state. X-ray Thomson scattering is a powerful technique for measuring these plasma parameters. However, the scattered signal is typically measured with little or no spatial resolution, which limits the ability to diagnose inhomogeneous plasmas. We report on the development of a new imaging x-ray Thomson spectrometer (IXTS) for the Omega laser facility. The diffraction of x-rays from a toroidally curved crystal creates high-resolution images that are spatially resolved along a one-dimensional profile while spectrally dispersing the radiation. An experiment is described in which we used the IXTS to measure the spatial temperature profile of a novel system. A low-density carbon foam was irradiated with intensities on the order of 10^15 W/cm^2, launching a planar blast wave. After a delay of several nanoseconds, x-rays created from irradiation of a nickel foil, scattered at 90 and were recorded by the IXTS. The resulting spatially resolved scattering spectra were analyzed to extract the temperature profile across the blast wave.

  9. Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves.

    PubMed

    Mao, Haojie; Unnikrishnan, Ginu; Rakesh, Vineet; Reifman, Jaques

    2015-12-01

    Multiple injury-causing mechanisms, such as wave propagation, skull flexure, cavitation, and head acceleration, have been proposed to explain blast-induced traumatic brain injury (bTBI). An accurate, quantitative description of the individual contribution of each of these mechanisms may be necessary to develop preventive strategies against bTBI. However, to date, despite numerous experimental and computational studies of bTBI, this question remains elusive. In this study, using a two-dimensional (2D) rat head model, we quantified the contribution of head acceleration to the biomechanical response of brain tissues when exposed to blast waves in a shock tube. We compared brain pressure at the coup, middle, and contre-coup regions between a 2D rat head model capable of simulating all mechanisms (i.e., the all-effects model) and an acceleration-only model. From our simulations, we determined that head acceleration contributed 36-45% of the maximum brain pressure at the coup region, had a negligible effect on the pressure at the middle region, and was responsible for the low pressure at the contre-coup region. Our findings also demonstrate that the current practice of measuring rat brain pressures close to the center of the brain would record only two-thirds of the maximum pressure observed at the coup region. Therefore, to accurately capture the effects of acceleration in experiments, we recommend placing a pressure sensor near the coup region, especially when investigating the acceleration mechanism using different experimental setups.

  10. Multiwavelength Observations of an Eruptive Flare: Evidence for Blast Waves and Break-Out

    NASA Astrophysics Data System (ADS)

    Kumar, Pankaj; Innes, D. E.

    2013-11-01

    Images of an east-limb flare on 3 November 2010 taken in the 131 Å channel of the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory provide a convincing example of a long current sheet below an erupting plasmoid, as predicted by the standard magnetic reconnection model of eruptive flares. However, the 171 Å and 193 Å channel images hint at an alternative scenario. These images reveal that large-scale waves with velocity greater than 1000 km s-1 propagated alongside and ahead of the erupting plasmoid. Just south of the plasmoid, the waves coincided with type-II radio emission, and to the north, where the waves propagated along plume-like structures, there was increased decimetric emission. Initially, the cavity around the hot plasmoid expanded. Later, when the erupting plasmoid reached the height of an overlying arcade system, the plasmoid structure changed, and the lower parts of the cavity collapsed inwards. Hot loops appeared alongside and below the erupting plasmoid. We consider a scenario in which the fast waves and the type-II emission were a consequence of a flare blast wave, and the cavity collapse and the hot loops resulted from the break-out of the flux rope through an overlying coronal arcade.

  11. Stability of ion acoustic solitary waves in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons having vortex-like velocity distribution

    NASA Astrophysics Data System (ADS)

    Das, Jayasree; Bandyopadhyay, Anup; Das, K. P.; Das

    2014-02-01

    Schamel's modified Korteweg-de Vries-Zakharov-Kuznetsov (S-ZK) equation, governing the behavior of long wavelength, weak nonlinear ion acoustic waves propagating obliquely to an external uniform static magnetic field in a plasma consisting of warm adiabatic ions and non-thermal electrons (due to the presence of fast energetic electrons) having vortex-like velocity distribution function (due to the presence of trapped electrons), immersed in a uniform (space-independent) and static (time-independent) magnetic field, admits solitary wave solutions having a sech 4 profile. The higher order stability of this solitary wave solution of the S-ZK equation has been analyzed with the help of multiple-scale perturbation expansion method of Allen and Rowlands (Allen, M. A. and Rowlands, G. 1993 J. Plasma Phys. 50, 413; 1995 J. Plasma Phys. 53, 63). The growth rate of instability is obtained correct to the order k 2, where k is the wave number of a long wavelength plane wave perturbation. It is found that the lowest order (at the order k) instability condition is strongly sensitive to the angle of propagation (δ) of the solitary wave with the external uniform static magnetic field, whereas at the next order (at the order k 2) the solitary wave solutions of the S-ZK equation are unstable irrespective of δ. It is also found that the growth rate of instability up to the order k 2 for the electrons having Boltzmann distribution is higher than that of the non-thermal electrons having vortex-like distribution for any fixed δ.

  12. Detection of undistorted continuous wave (CW) electron paramagnetic resonance (EPR) spectra with non-adiabatic rapid sweep (NARS) of the magnetic field

    PubMed Central

    Kittell, Aaron W.; Camenisch, Theodore G.; Ratke, Joseph J.; Sidabras, Jason W.; Hyde, James S.

    2011-01-01

    A continuous wave (CW) electron paramagnetic resonance (EPR) spectrum is typically displayed as the first harmonic response to the application of 100 kHz magnetic field modulation, which is used to enhance sensitivity by reducing the level of 1/f noise. However, magnetic field modulation of any amplitude causes spectral broadening and sacrifices EPR spectral intensity by at least a factor of two. In the work presented here, a CW rapid-scan spectroscopic technique that avoids these compromises and also provides a means of avoiding 1/f noise is developed. This technique, termed non-adiabatic rapid sweep (NARS) EPR, consists of repetitively sweeping the polarizing magnetic field in a linear manner over a spectral fragment with a small coil at a repetition rate that is sufficiently high that receiver noise, microwave phase noise, and environmental microphonics, each of which has 1/f characteristics, are overcome. Nevertheless, the rate of sweep is sufficiently slow that adiabatic responses are avoided and the spin system is always close to thermal equilibrium. The repetitively acquired spectra from the spectral fragment are averaged. Under these conditions, undistorted pure absorption spectra are obtained without broadening or loss of signal intensity. A digital filter such as a moving average is applied to remove high frequency noise, which is approximately equivalent in bandwidth to use of an integrating time constant in conventional field modulation with lock-in detection. Nitroxide spectra at L- and X-band are presented. PMID:21741868

  13. Fluid/Structure Interaction Computational Investigation of Blast-Wave Mitigation Efficacy of the Advanced Combat Helmet

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Bell, W. C.; Pandurangan, B.; Glomski, P. S.

    2011-08-01

    To combat the problem of traumatic brain injury (TBI), a signature injury of the current military conflicts, there is an urgent need to design head protection systems with superior blast/ballistic impact mitigation capabilities. Toward that end, the blast impact mitigation performance of an advanced combat helmet (ACH) head protection system equipped with polyurea suspension pads and subjected to two different blast peak pressure loadings has been investigated computationally. A fairly detailed (Lagrangian) finite-element model of a helmet/skull/brain assembly is first constructed and placed into an Eulerian air domain through which a single planar blast wave propagates. A combined Eulerian/Lagrangian transient nonlinear dynamics computational fluid/solid interaction analysis is next conducted in order to assess the extent of reduction in intra-cranial shock-wave ingress (responsible for TBI). This was done by comparing temporal evolutions of intra-cranial normal and shear stresses for the cases of an unprotected head and the helmet-protected head and by correlating these quantities with the three most common types of mild traumatic brain injury (mTBI), i.e., axonal damage, contusion, and subdural hemorrhage. The results obtained show that the ACH provides some level of protection against all investigated types of mTBI and that the level of protection increases somewhat with an increase in blast peak pressure. In order to rationalize the aforementioned findings, a shockwave propagation/reflection analysis is carried out for the unprotected head and helmet-protected head cases. The analysis qualitatively corroborated the results pertaining to the blast-mitigation efficacy of an ACH, but also suggested that there are additional shockwave energy dissipation phenomena which play an important role in the mechanical response of the unprotected/protected head to blast impact.

  14. Localization of small arms fire using acoustic measurements of muzzle blast and/or ballistic shock wave arrivals.

    PubMed

    Lo, Kam W; Ferguson, Brian G

    2012-11-01

    The accurate localization of small arms fire using fixed acoustic sensors is considered. First, the conventional wavefront-curvature passive ranging method, which requires only differential time-of-arrival (DTOA) measurements of the muzzle blast wave to estimate the source position, is modified to account for sensor positions that are not strictly collinear (bowed array). Second, an existing single-sensor-node ballistic model-based localization method, which requires both DTOA and differential angle-of-arrival (DAOA) measurements of the muzzle blast wave and ballistic shock wave, is improved by replacing the basic external ballistics model (which describes the bullet's deceleration along its trajectory) with a more rigorous model and replacing the look-up table ranging procedure with a nonlinear (or polynomial) equation-based ranging procedure. Third, a new multiple-sensor-node ballistic model-based localization method, which requires only DTOA measurements of the ballistic shock wave to localize the point of fire, is formulated. The first method is applicable to situations when only the muzzle blast wave is received, whereas the third method applies when only the ballistic shock wave is received. The effectiveness of each of these methods is verified using an extensive set of real data recorded during a 7 day field experiment. PMID:23145587

  15. Localization of small arms fire using acoustic measurements of muzzle blast and/or ballistic shock wave arrivals.

    PubMed

    Lo, Kam W; Ferguson, Brian G

    2012-11-01

    The accurate localization of small arms fire using fixed acoustic sensors is considered. First, the conventional wavefront-curvature passive ranging method, which requires only differential time-of-arrival (DTOA) measurements of the muzzle blast wave to estimate the source position, is modified to account for sensor positions that are not strictly collinear (bowed array). Second, an existing single-sensor-node ballistic model-based localization method, which requires both DTOA and differential angle-of-arrival (DAOA) measurements of the muzzle blast wave and ballistic shock wave, is improved by replacing the basic external ballistics model (which describes the bullet's deceleration along its trajectory) with a more rigorous model and replacing the look-up table ranging procedure with a nonlinear (or polynomial) equation-based ranging procedure. Third, a new multiple-sensor-node ballistic model-based localization method, which requires only DTOA measurements of the ballistic shock wave to localize the point of fire, is formulated. The first method is applicable to situations when only the muzzle blast wave is received, whereas the third method applies when only the ballistic shock wave is received. The effectiveness of each of these methods is verified using an extensive set of real data recorded during a 7 day field experiment.

  16. Numerical simulation of the fluid-structure interaction between air blast waves and soil structure

    NASA Astrophysics Data System (ADS)

    Umar, S.; Risby, M. S.; Albert, A. Luthfi; Norazman, M.; Ariffin, I.; Alias, Y. Muhamad

    2014-03-01

    Normally, an explosion threat on free field especially from high explosives is very dangerous due to the ground shocks generated that have high impulsive load. Nowadays, explosion threats do not only occur in the battlefield, but also in industries and urban areas. In industries such as oil and gas, explosion threats may occur on logistic transportation, maintenance, production, and distribution pipeline that are located underground to supply crude oil. Therefore, the appropriate blast resistances are a priority requirement that can be obtained through an assessment on the structural response, material strength and impact pattern of material due to ground shock. A highly impulsive load from ground shocks is a dynamic load due to its loading time which is faster than ground response time. Of late, almost all blast studies consider and analyze the ground shock in the fluid-structure interaction (FSI) because of its influence on the propagation and interaction of ground shock. Furthermore, analysis in the FSI integrates action of ground shock and reaction of ground on calculations of velocity, pressure and force. Therefore, this integration of the FSI has the capability to deliver the ground shock analysis on simulation to be closer to experimental investigation results. In this study, the FSI was implemented on AUTODYN computer code by using Euler-Godunov and the arbitrary Lagrangian-Eulerian (ALE). Euler-Godunov has the capability to deliver a structural computation on a 3D analysis, while ALE delivers an arbitrary calculation that is appropriate for a FSI analysis. In addition, ALE scheme delivers fine approach on little deformation analysis with an arbitrary motion, while the Euler-Godunov scheme delivers fine approach on a large deformation analysis. An integrated scheme based on Euler-Godunov and the arbitrary Lagrangian-Eulerian allows us to analyze the blast propagation waves and structural interaction simultaneously.

  17. Brain Response to Primary Blast Wave Using Validated Finite Element Models of Human Head and Advanced Combat Helmet

    PubMed Central

    Zhang, Liying; Makwana, Rahul; Sharma, Sumit

    2013-01-01

    Blast-induced traumatic brain injury has emerged as a “signature injury” in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH), a finite element (FE) study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27–0.66 MPa) from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP) in the head ranged from 0.68 to 1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10–35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44%) was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%). The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence “iso-damage” curves for brain injury are likely different than the Bowen

  18. Mechanism of Traumatic Brain Injury at Distant Locations After Exposure to Blast Waves: Preliminary Results from Animal and Phantom Experiments.

    PubMed

    Nakagawa, Atsuhiro; Ohtani, Kiyonobu; Goda, Keisuke; Kudo, Daisuke; Arafune, Tatsuhiko; Washio, Toshikatsu; Tominaga, Teiji

    2016-01-01

    Purpose Primary blast-induced traumatic brain injury (bTBI) is the least understood of the four phases of blast injury. Distant injury induced by the blast wave, on the opposite side from the wave entry, is not well understood. This study investigated the mechanism of distant injury in bTBI. Materials and Methods Eight 8-week-old male Sprague-Dawley rats were divided into two groups: group 1 served as the control group and did not receive any shock wave (SW) exposure; group 2 was exposed to SWs (12.5 ± 2.5 MPa). Propagation of SWs within a brain phantom was evaluated by visualization, pressure measurement, and numerical simulation. Results Intracerebral hemorrhage near the ignition site and elongation of the distant nucleus were observed, despite no apparent damage between the two locations in the animal experiment. Visualization, pressure measurement, and numerical simulation indicated the presence of complex wave dynamics accompanying a sudden increase in pressure, followed by negative pressure in the phantom experiment. Conclusion A local increase in pressure above the threshold caused by interference of reflection and rarefaction waves in the vicinity of the brain-skull surface may cause distant injury in bTBI. PMID:27165867

  19. Study of radiative blast waves generated on the Z-beamlet laser.

    SciTech Connect

    Edens, Aaron D.; Schwarz, Jens

    2012-02-01

    This document describes the original goals of the project to study the Vishniac Overstability on blast waves produced using the Z-Beamlet laser facility as well as the actual results. The proposed work was to build on earlier work on the facility and result in the best characterized set of data for such phenomena in the laboratory. To accomplish the goals it was necessary to modify the existing probe laser at the facility so that it could take multiple images over the course of 1-2 microseconds. Troubles with modifying the probe laser are detailed as well as the work that went into said modifications. The probe laser modification ended up taking the entire length of the project and were the major accomplishment of the research.

  20. A viscous blast-wave model for high energy heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Jaiswal, Amaresh; Koch, Volker

    2016-07-01

    Employing a viscosity-based survival scale for initial geometrical perturbations formed in relativistic heavy-ion collisions, we model the radial flow velocity at freeze-out. Subsequently, we use the Cooper-Frye freeze-out prescription, with viscous corrections to the distribution function, to extract the transverse momentum dependence of particle yields and flow harmonics. We fit the model parameters for central collisions, by fitting the spectra of identified particles at the Large Hadron Collider (LHC), and estimate them for other centralities using simple hydrodynamic relations. We use the results of Monte Carlo Glauber model for initial eccentricities. We demonstrate that this improved viscous blast-wave model leads to good agreement with transverse momentum distribution of elliptic and triangular flow for all centralities and estimate the shear viscosity to entropy density ratio η/s ≃ 0.24 at the LHC.

  1. Revisiting the Emission from Relativistic Blast Waves in a Density-jump Medium

    NASA Astrophysics Data System (ADS)

    Geng, J. J.; Wu, X. F.; Li, Liang; Huang, Y. F.; Dai, Z. G.

    2014-09-01

    Re-brightening bumps are frequently observed in gamma-ray burst afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has been questioned by recent works. We develop a set of differential equations to calculate the relativistic outflow encountering the density-jump by extending the work of Huang et al. This approach is a semi-analytic method and is very convenient. Our results show that late high-amplitude bumps cannot be produced under common conditions, rather only a short plateau may emerge even when the encounter occurs at an early time (<104 s). In general, our results disfavor the density-jump origin for those observed bumps, which is consistent with the conclusion drawn from full hydrodynamics studies. The bumps thus should be caused by other scenarios.

  2. Supernovae and Their Expanding Blast Waves during the Early Evolution of Galactic Globular Clusters

    NASA Astrophysics Data System (ADS)

    Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana; Silich, Sergiy; Cassisi, Santi

    2015-11-01

    Our arguments deal with the early evolution of Galactic globular clusters and show why only a few of the supernovae (SNe) products were retained within globular clusters and only in the most massive cases (M ≥ 106 M⊙), while less massive clusters were not contaminated at all by SNe. Here, we show that SN blast waves evolving in a steep density gradient undergo blowout and end up discharging their energy and metals into the medium surrounding the clusters. This inhibits the dispersal and the contamination of the gas left over from a first stellar generation. Only the ejecta from well-centered SNe that evolve into a high-density medium available for a second stellar generation (2SG) in the most massive clusters would be retained. These are likely to mix their products with the remaining gas, eventually leading in these cases to an Fe-contaminated 2SG.

  3. Self-generated magnetic fields in blast-wave driven Rayleigh-Taylor experiments

    NASA Astrophysics Data System (ADS)

    Flaig, Markus; Plewa, Tomasz

    2015-12-01

    We study the effect of self-generated magnetic fields in two-dimensional computer models of blast-wave driven high-energy density Rayleigh-Taylor instability (RTI) experiments. Previous works [1,2] suggested that such fields have the potential to influence the RTI morphology and mixing. When neglecting the friction force between electrons and ions, we do indeed find that dynamically important (β≲103) magnetic fields are generated. However, in the more realistic case where the friction force is accounted for, the resulting fields are much weaker, β≳105 , and can no longer influence the dynamics of the system. Although we find no evidence for dynamically important magnetic fields being created in the two-dimensional case studied here, the situation might be different in a three-dimensional setup, which will be addressed in a future study.

  4. Revisiting the emission from relativistic blast waves in a density-jump medium

    SciTech Connect

    Geng, J. J.; Huang, Y. F.; Dai, Z. G.; Wu, X. F.; Li, Liang E-mail: dzg@nju.edu.cn

    2014-09-01

    Re-brightening bumps are frequently observed in gamma-ray burst afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has been questioned by recent works. We develop a set of differential equations to calculate the relativistic outflow encountering the density-jump by extending the work of Huang et al. This approach is a semi-analytic method and is very convenient. Our results show that late high-amplitude bumps cannot be produced under common conditions, rather only a short plateau may emerge even when the encounter occurs at an early time (<10{sup 4} s). In general, our results disfavor the density-jump origin for those observed bumps, which is consistent with the conclusion drawn from full hydrodynamics studies. The bumps thus should be caused by other scenarios.

  5. Simulations of Magnetic Field Generation in Laser-Produced Blast Waves

    NASA Astrophysics Data System (ADS)

    Lamb, D.; Fatenejad, M.; Gregori, G.; Miniati, F.; Park, H.-S.; Remington, B.; Ravasio, A.; Koenig, M.; Murphy, C. D.

    2011-10-01

    Magnetic fields are ubiquitous in the Universe. The origin of these fields and process by which they are amplified are not fully understood, although amplification is thought to involve turbulence. Experiments being conducted at medium-scale laser facilities (such as the LULI laser the Janus laser) can investigate the self-generation of magnetic fields under conditions that resemble astrophysical shocks. In these experiments, two 527 nm, 1.5 ns long laser beams are focused onto a 500 μm diameter graphite rod producing an explosion and asymmetric blast wave into a Helium filled chamber. A variety of diagnostics measure the velocity, electron density, and show that a large scale magnetic field is produced. We report preliminary hydrodynamic and MHD simulations using FLASH of a simplified version of the experiment. The results provide insights into the origin and generation of the magnetic field. This work was partially supported by the US DOE, the European Research Council, and Laserlab Europe.

  6. SUPERNOVAE AND THEIR EXPANDING BLAST WAVES DURING THE EARLY EVOLUTION OF GALACTIC GLOBULAR CLUSTERS

    SciTech Connect

    Tenorio-Tagle, Guillermo; Silich, Sergiy; Muñoz-Tuñón, Casiana; Cassisi, Santi E-mail: cmt@iac.es

    2015-11-20

    Our arguments deal with the early evolution of Galactic globular clusters and show why only a few of the supernovae (SNe) products were retained within globular clusters and only in the most massive cases (M ≥ 10{sup 6} M{sub ⊙}), while less massive clusters were not contaminated at all by SNe. Here, we show that SN blast waves evolving in a steep density gradient undergo blowout and end up discharging their energy and metals into the medium surrounding the clusters. This inhibits the dispersal and the contamination of the gas left over from a first stellar generation. Only the ejecta from well-centered SNe that evolve into a high-density medium available for a second stellar generation (2SG) in the most massive clusters would be retained. These are likely to mix their products with the remaining gas, eventually leading in these cases to an Fe-contaminated 2SG.

  7. ON THE AMPLIFICATION OF MAGNETIC FIELD BY A SUPERNOVA BLAST SHOCK WAVE IN A TURBULENT MEDIUM

    SciTech Connect

    Guo Fan; Li Shengtai; Li Hui; Li, David; Giacalone, Joe; Jokipii, J. R.

    2012-03-10

    We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the 'rippled' shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

  8. Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves.

    PubMed

    Mao, Haojie; Unnikrishnan, Ginu; Rakesh, Vineet; Reifman, Jaques

    2015-12-01

    Multiple injury-causing mechanisms, such as wave propagation, skull flexure, cavitation, and head acceleration, have been proposed to explain blast-induced traumatic brain injury (bTBI). An accurate, quantitative description of the individual contribution of each of these mechanisms may be necessary to develop preventive strategies against bTBI. However, to date, despite numerous experimental and computational studies of bTBI, this question remains elusive. In this study, using a two-dimensional (2D) rat head model, we quantified the contribution of head acceleration to the biomechanical response of brain tissues when exposed to blast waves in a shock tube. We compared brain pressure at the coup, middle, and contre-coup regions between a 2D rat head model capable of simulating all mechanisms (i.e., the all-effects model) and an acceleration-only model. From our simulations, we determined that head acceleration contributed 36-45% of the maximum brain pressure at the coup region, had a negligible effect on the pressure at the middle region, and was responsible for the low pressure at the contre-coup region. Our findings also demonstrate that the current practice of measuring rat brain pressures close to the center of the brain would record only two-thirds of the maximum pressure observed at the coup region. Therefore, to accurately capture the effects of acceleration in experiments, we recommend placing a pressure sensor near the coup region, especially when investigating the acceleration mechanism using different experimental setups. PMID:26458125

  9. Comparison of weak-shock reflection factors for wedges, cylinders and blast waves

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1992-07-01

    Ernst Mach (1838--1916) was the first to discover an irregular reflection phenomenon of shock waves, as is well known in our community. In fact, this occurred in 1875 -- three years earlier than usually assumed in the literature. A facsimile of the paper in which he mentioned a special shock wave behavior is shown in a figure. However, it is correct that Mach gave the physical interpretation of this phenomenon in 1878. Since Mach`s discovery of an irregular shock reflection pattern 117 years ago, new shock configurations have been discovered -- one of the most recent examples is the so-called {open_quotes}von Neumann reflection{close_quotes} for weak shocks as reported by Colella and Henderson in 1990. Due to active research efforts related to shock reflection, especially in the last two decades, we now have a relatively detailed understanding of reflection phenomena and of transition conditions from one reflection configuration to another. The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: (1) square-wave planar shock reflection from wedges, (2) square-wave planar shock reflection from cylinders and (3) spherical blast wave reflection from a planar surface. The authors restrict themselves to weak shocks. Following Henderson`s definition, shocks with a Mach number of M{sub 0} < 1.56 in air or with an overpressure of {Delta}p{sub I} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  10. Comparison of weak-shock reflection factors for wedges, cylinders and blast waves

    SciTech Connect

    Reichenbach, H. , Freiburg im Breisgau ); Kuhl, A.L. )

    1992-07-01

    Ernst Mach (1838--1916) was the first to discover an irregular reflection phenomenon of shock waves, as is well known in our community. In fact, this occurred in 1875 -- three years earlier than usually assumed in the literature. A facsimile of the paper in which he mentioned a special shock wave behavior is shown in a figure. However, it is correct that Mach gave the physical interpretation of this phenomenon in 1878. Since Mach's discovery of an irregular shock reflection pattern 117 years ago, new shock configurations have been discovered -- one of the most recent examples is the so-called [open quotes]von Neumann reflection[close quotes] for weak shocks as reported by Colella and Henderson in 1990. Due to active research efforts related to shock reflection, especially in the last two decades, we now have a relatively detailed understanding of reflection phenomena and of transition conditions from one reflection configuration to another. The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: (1) square-wave planar shock reflection from wedges, (2) square-wave planar shock reflection from cylinders and (3) spherical blast wave reflection from a planar surface. The authors restrict themselves to weak shocks. Following Henderson's definition, shocks with a Mach number of M[sub 0] < 1.56 in air or with an overpressure of [Delta]p[sub I] < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  11. Exposure of the Thorax to a Sublethal Blast Wave Causes a Hydrodynamic Pulse That Leads to Perivenular Inflammation in the Brain

    PubMed Central

    Pampori, Adam; Keledjian, Kaspar; Tosun, Cigdem; Schwartzbauer, Gary; Ivanova, Svetlana; Gerzanich, Volodymyr

    2014-01-01

    Abstract Traumatic brain injury (TBI) caused by an explosive blast (blast-TBI) is postulated to result, in part, from transvascular transmission to the brain of a hydrodynamic pulse (a.k.a., volumetric blood surge, ballistic pressure wave, hydrostatic shock, or hydraulic shock) induced in major intrathoracic blood vessels. This mechanism of blast-TBI has not been demonstrated directly. We tested the hypothesis that a blast wave impacting the thorax would induce a hydrodynamic pulse that would cause pathological changes in the brain. We constructed a Thorax-Only Blast Injury Apparatus (TOBIA) and a Jugular-Only Blast Injury Apparatus (JOBIA). TOBIA delivered a collimated blast wave to the right lateral thorax of a rat, precluding direct impact on the cranium. JOBIA delivered a blast wave to the fluid-filled port of an extracorporeal intravenous infusion device whose catheter was inserted retrograde into the jugular vein, precluding lung injury. Long Evans rats were subjected to sublethal injury by TOBIA or JOBIA. Blast injury induced by TOBIA was characterized by apnea and diffuse bilateral hemorrhagic injury to the lungs associated with a transient reduction in pulse oximetry signals. Immunolabeling 24 h after injury by TOBIA showed up-regulation of tumor necrosis factor alpha, ED-1, sulfonylurea receptor 1 (Sur1), and glial fibrillary acidic protein in veins or perivenular tissues and microvessels throughout the brain. The perivenular inflammatory effects induced by TOBIA were prevented by ligating the jugular vein and were reproduced using JOBIA. We conclude that blast injury to the thorax leads to perivenular inflammation, Sur1 up-regulation, and reactive astrocytosis resulting from the induction of a hydrodynamic pulse in the vasculature. PMID:24673157

  12. Modeling blast waves, gas and particles dispersion in urban and hilly ground areas.

    PubMed

    Hank, S; Saurel, R; Le Métayer, O; Lapébie, E

    2014-09-15

    The numerical simulation of shock and blast waves as well as particles dispersion in highly heterogeneous media such as cities, urban places, industrial plants and part of countries is addressed. Examples of phenomena under study are chemical gas products dispersion from damaged vessels, gas dispersion in urban places under explosion conditions, shock wave propagation in urban environment. A three-dimensional simulation multiphase flow code (HI2LO) is developed in this aim. To simplify the consideration of complex geometries, a heterogeneous discrete formulation is developed. When dealing with large scale domains, such as countries, the topography is considered with the help of elevation data. Meteorological conditions are also considered, in particular regarding complex temperature and wind profiles. Heat and mass transfers on sub-scale objects, such as buildings, trees and other obstacles are considered as well. Particles motion is addressed through a new turbulence model involving a single parameter to describe accurately plumes. Validations against experiments in basic situations are presented as well as examples of industrial and environmental computations. PMID:25199503

  13. Atomic long-range order effects on Curie temperature and adiabatic spin-wave dynamics in strained Fe-Co alloy films

    NASA Astrophysics Data System (ADS)

    Schönecker, Stephan; Li, Xiaoqing; Johansson, Börje; Vitos, Levente

    2016-08-01

    The strained Fe-Co alloy in body-centered tetragonal (bct) structure has raised considerable interest due to its giant uniaxial magnetocrystalline anisotropy energy. On the basis of the classical Heisenberg Hamiltonian with ab initio interatomic exchange interactions, we perform a theoretical study of fundamental finite temperature magnetic properties of Fe1 -xCox alloy films as a function of three variables: chemical composition 0.3 ≤x ≤0.8 , bct geometry [a ,c (a )] arising from in-plane strain and associated out-of-plane relaxation, and atomic long-range order (ALRO). The Curie temperatures TC(x ,a ) obtained from Monte Carlo simulations display a competition between a pronounced dependence on tetragonality, strong ferromagnetism in the Co-rich alloy, and the beginning instability of ferromagnetic order in the Fe-rich alloy when c /a →√{2 } . Atomic ordering enhances TC and arises mainly due to different distributions of atoms in neighboring coordination shells rather than altering exchange interactions significantly. We investigate the ordering effect on the shape of the adiabatic spin-wave spectrum for selected pairs (x ,a ) . Our results indicate that long-wavelength acoustic spin-wave excitations show dependencies on x , a , and ALRO similar to those of TC. The directional anisotropy of the spin-wave stiffness d (x ,a ) peaks in narrow ranges of composition and tetragonality. ALRO exhibits a strong effect on d for near equiconcentration Fe-Co. We also discuss our findings in the context of employing Fe-Co as perpendicular magnetic recording medium.

  14. Numerical reconstruction of part of an actual blast-wave flow field to agree with available experimental data

    NASA Astrophysics Data System (ADS)

    Lau, S. C. M.; Gottlieb, J. J.

    1983-11-01

    A method of solution is presented and validated for the numerical reconstruction of a certain part of an actual blast-wave flow field of interest for planar, cylindrical and spherical explosions, away from the explosion source where the blast-wave has become sufficiently weak that real-gas effects are unimportant. This method involves, essentially, a trial-and-error process of constructing the best possible path of a fluid particle or equivalent piston at the upstream side of the flow field of interest such that the resulting flow field constructed numerically in front of the equivalent moving piston agrees as well as possible with all available although limited experimental data. The relatively new random-choice method was suitably modified to easily handle the numerical computations of the nonstationary flow in front of the moving piston. Finally, the present method is used to reconstruct the flow field for past TNT and ANFO explosions, for which the blast-wave amplitudes are less than about 1 MPa. These results are presented in convenient graphical and tabular form, scaled for the case of a 1-kg TNT surface explosion or its equivalent in a standard atmosphere, so that they can be utilized readily for different sized explosions at the same or other atmospheric conditions.

  15. Subjective loudness of simulated quarry blast waves, with implications for the transition from impulsive to continuous sound.

    PubMed

    Niedzwiecki, A; Ribner, H S

    1979-05-01

    The tradeoff between amplitude and duration for equal loudness was explored for idealized quarry blast waves. An extended low-frequency response loudspeaker-driven simulation booth was employed with computer-generated imput test signals. In place of actual irregular blast waves, the simulated signatures were composed of sequences of identical shock-decay impulses of 25 ms duration and 0.2 ms rise time. Sequences of 1--16 impulses yielded overall durations of 25--400 ms. At the short durations the loudness was found to increase 2 dB for each doubling of duration; above 100 ms the increase was progressively lower, approaching as an asymptote the level for continuous sound. The results were compared with theoretical predictions: for this purpose the spectral method of Johnson and Robinson, well varified in our earlier studies of sonic boom impulses, was used. The shorter quarry blast judgments (T less than or equal to 100 ms) were found to be in very good agreement in terms of relative loudness levels. With an ad hoc--but physically plausible--modification (including adjustment of the critical integration time of the ear) the predictive method was extended to encompass the long duration signals as well. Thus the applicability of the method has been demonstrated for other types of transient sounds than the N wave; and the extension of the method tentatively appears to bridge the range between impulsive and continuous sounds of similar spectral content. PMID:458043

  16. Subjective loudness of simulated quarry blast waves, with implications for the transition from impulsive to continuous sound.

    PubMed

    Niedzwiecki, A; Ribner, H S

    1979-05-01

    The tradeoff between amplitude and duration for equal loudness was explored for idealized quarry blast waves. An extended low-frequency response loudspeaker-driven simulation booth was employed with computer-generated imput test signals. In place of actual irregular blast waves, the simulated signatures were composed of sequences of identical shock-decay impulses of 25 ms duration and 0.2 ms rise time. Sequences of 1--16 impulses yielded overall durations of 25--400 ms. At the short durations the loudness was found to increase 2 dB for each doubling of duration; above 100 ms the increase was progressively lower, approaching as an asymptote the level for continuous sound. The results were compared with theoretical predictions: for this purpose the spectral method of Johnson and Robinson, well varified in our earlier studies of sonic boom impulses, was used. The shorter quarry blast judgments (T less than or equal to 100 ms) were found to be in very good agreement in terms of relative loudness levels. With an ad hoc--but physically plausible--modification (including adjustment of the critical integration time of the ear) the predictive method was extended to encompass the long duration signals as well. Thus the applicability of the method has been demonstrated for other types of transient sounds than the N wave; and the extension of the method tentatively appears to bridge the range between impulsive and continuous sounds of similar spectral content.

  17. Blast-wave-sphere interaction using a laser-produced plasma: an experiment motivated by supernova 1987A.

    PubMed

    Kang, Y G; Nishihara, K; Nishimura, H; Takabe, H; Sunahara, A; Norimatsu, T; Nagai, K; Kim, H; Nakatsuka, M; Kong, H J; Zabusky, N J

    2001-10-01

    We present x-ray shadowgraphs from a high Mach number ( approximately 20) laboratory environment that simulate outward flowing ejecta matter from supernovae that interact with ambient cloud matter. Using a laser-plastic foil interaction, we generate a "complex" blast wave (a supersonic flow containing forward and reverse shock waves and a contact discontinuity between them) that interacts with a high-density (100 times ambient) sphere. The experimental results, including vorticity localization, compare favorably with two-dimensional axisymmetric hydrodynamic simulations. PMID:11690182

  18. A nonlinear solid shell element formulation for analysis of composite panels under blast wave pressure loading

    NASA Astrophysics Data System (ADS)

    Park, Hun

    A comprehensive methodology to accurately predict the dynamic response of composite panels under blast wave pressure loading has been successfully developed for the first time. It includes the modeling of geometrically nonlinear dynamic effect, progressive failure and strain-rate effect on constitutive equation and strength. For dynamic analysis, a nonlinear solid shell element formulation is combined with the trapezoidal rule for numerical integration in time. The progressive damage incorporates the effect of the material failure, such as fiber failure, matrix cracking and fiber-matrix shearing failure on the stiffness and strength. Material degradation models based on the rule of mixtures are proposed for each failure mode. To implement the strain-rate effect on the constitutive equation of the material, a viscoplastic model is adopted. In this model, three material parameters are determined by conducting uniaxial tension tests on off-axis specimen. The effect of strain rates on material strength is implemented via the linear least square fit of the test data. A key ingredient of the analysis is a geometrically nonlinear solid shell element based on the assumed strain formulation to alleviate element locking. In this approach, the composite shell is treated as a three-dimensional solid. Accordingly, the change of shell thickness is allowed and the kinematics of deformation is described by six vector components at a point on the shell midsurface. The mass matrix always remains constant during the analysis. Example problems under static and dynamic loadings are solved to investigate the behavior of composite panels undergoing large deformation while experiencing material damage. The analysis results are compared with the test data available. Results of the numerical analysis show that the effect of the progressive failure and strain-rates on structural responses are considerable. For a composite plate under static pressure loadings, maximum displacement and

  19. Observation and modeling of mixing-layer development in HED blast-wave-driven shear flow

    NASA Astrophysics Data System (ADS)

    di Stefano, Carlos

    2013-10-01

    This talk describes work exploring the sensitivity to initial conditions of hydrodynamic mixing-layer growth due to shear flow in the high-energy-density regime. This work features an approach in two parts, experimental and theoretical. First, an experiment, conducted at the OMEGA-60 laser facility, seeks to measure the development of such a mixing layer. This is accomplished by placing a layer of low-density (initially of either 0.05 or 0.1 g/cm3, to vary the system's Atwood number) carbon foam against a layer of higher-density (initially 1.4 g/cm3) polyamide-imide that has been machined to a nominally-flat surface at its interface with the foam. Inherent roughness of this surface's finish is precisely measured and varied from piece to piece. Ten simultaneous OMEGA beams, comprising a 4.5 kJ, 1-ns pulse focused to a roughly 1-mm-diameter spot, irradiate a thin polycarbonate ablator, driving a blast wave into the foam, parallel to its interface with the polyamide-imide. The ablator is framed by a gold washer, such that the blast wave is driven only into the foam, and not into the polyamide-imide. The subsequent forward motion of the shocked foam creates the desired shear effect, and the system is imaged by X-ray radiography 35 ns after the beginning of the driving laser pulse. Second, a simulation is performed, intending to replicate the flow observed in the experiment as closely as possible. Using the resulting simulated flow parameters, an analytical model can be used to predict the evolution of the mixing layer, as well as track the motion of the fluid in the experiment prior to the snapshot seen in the radiograph. The ability of the model to predict growth of the mixing layer under the various conditions observed in the experiment is then examined. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE

  20. Degenerate adiabatic perturbation theory: Foundations and applications

    NASA Astrophysics Data System (ADS)

    Rigolin, Gustavo; Ortiz, Gerardo

    2014-08-01

    We present details and expand on the framework leading to the recently introduced degenerate adiabatic perturbation theory [Phys. Rev. Lett. 104, 170406 (2010), 10.1103/PhysRevLett.104.170406], and on the formulation of the degenerate adiabatic theorem, along with its necessary and sufficient conditions [given in Phys. Rev. A 85, 062111 (2012), 10.1103/PhysRevA.85.062111]. We start with the adiabatic approximation for degenerate Hamiltonians that paves the way to a clear and rigorous statement of the associated degenerate adiabatic theorem, where the non-Abelian geometric phase (Wilczek-Zee phase) plays a central role to its quantitative formulation. We then describe the degenerate adiabatic perturbation theory, whose zeroth-order term is the degenerate adiabatic approximation, in its full generality. The parameter in the perturbative power-series expansion of the time-dependent wave function is directly associated to the inverse of the time it takes to drive the system from its initial to its final state. With the aid of the degenerate adiabatic perturbation theory we obtain rigorous necessary and sufficient conditions for the validity of the adiabatic theorem of quantum mechanics. Finally, to illustrate the power and wide scope of the methodology, we apply the framework to a degenerate Hamiltonian, whose closed-form time-dependent wave function is derived exactly, and also to other nonexactly solvable Hamiltonians whose solutions are numerically computed.

  1. The adiabatic energy change of plasma electrons and the frame dependence of the cross-shock potential at collisionless magnetosonic shock waves

    NASA Technical Reports Server (NTRS)

    Goodrich, C. C.; Scudder, J. D.

    1984-01-01

    The adiabatic energy gain of electrons in the stationary electric and magnetic field structure of collisionless shock waves was examined analytically in reference to conditions of the earth's bow shock. The study was performed to characterize the behavior of electrons interacting with the cross-shock potential. A normal incidence frame (NIF) was adopted in order to calculate the reversible energy change across a time stationary shock, and comparisons were made with predictions made by the de Hoffman-Teller (HT) model (1950). The electron energy gain, about 20-50 eV, is demonstrated to be consistent with a 200-500 eV potential jump in the bow shock quasi-perpendicular geometry. The electrons lose energy working against the solar wind motional electric field. The reversible energy process is close to that modeled by HT, which predicts that the motional electric field vanishes and the electron energy gain from the electric potential is equated to the ion energy loss to the potential.

  2. Time-dependent and radiation field effects on collisional-radiative simulations of radiative properties of blast waves launched in clusters of xenon

    NASA Astrophysics Data System (ADS)

    Rodriguez, R.; Espinosa, G.; Gil, J. M.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

    2015-12-01

    Radiative shock waves are ubiquitous throughout the universe and play a crucial role in the transport of energy into the interstellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible conditions. In some laboratory experiments radiative blast waves are launched in clusters of gases by means of the direct deposition of the laser energy. In this work, by using a collisional-radiative model, we perform an analysis of the plasma level populations and radiative properties of a blast wave launched in a xenon cluster. In particular, for both the shocked and unshocked material, we study the influence of different effects such as LTE, steady-state or time-dependent NLTE simulations, plasma self-absorption or external radiation field in the determination of those properties and also in the diagnosis of the electron temperature of the blast wave.

  3. Numerical simulation of long-duration blast wave evolution in confined facilities

    NASA Astrophysics Data System (ADS)

    Togashi, F.; Baum, J. D.; Mestreau, E.; Löhner, R.; Sunshine, D.

    2010-10-01

    The objective of this research effort was to investigate the quasi-steady flow field produced by explosives in confined facilities. In this effort we modeled tests in which a high explosive (HE) cylindrical charge was hung in the center of a room and detonated. The HEs used for the tests were C-4 and AFX 757. While C-4 is just slightly under-oxidized and is typically modeled as an ideal explosive, AFX 757 includes a significant percentage of aluminum particles, so long-time afterburning and energy release must be considered. The Lawrence Livermore National Laboratory (LLNL)-produced thermo-chemical equilibrium algorithm, “Cheetah”, was used to estimate the remaining burnable detonation products. From these remaining species, the afterburning energy was computed and added to the flow field. Computations of the detonation and afterburn of two HEs in the confined multi-room facility were performed. The results demonstrate excellent agreement with available experimental data in terms of blast wave time of arrival, peak shock amplitude, reverberation, and total impulse (and hence, total energy release, via either the detonation or afterburn processes.

  4. Spectral properties of blast-wave models of gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Meszaros, P.; Rees, M. J.; Papathanassiou, H.

    1994-01-01

    We calculate the spectrum of blast-wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find that the radiation efficiency is high and leads to nonthermal spectra with breaks at various energies comparable to those observed in the gamma-ray range. Radiation is also predicted at other wavebands, in particular at X-ray, optical/UV, and GeV/TeV energies. We discuss the spectra as a function of duration for three basic types of models, and for cosmological, halo, and galactic disk distances. We also evaluate the gamma-ray fluences and the spectral characteristics for a range of external densities. Impulsive burst models at cosmological distances can satisfy the conventional X-ray paucity constraint S(sub x)/S(sub gamma)less than a few percent over a wide range of durations, but galactic models can do so only for bursts shorter than a few seconds, unless additional assumptions are made. The emissivity is generally larger for bursts in a denser external environment, with the efficiency increasing up to the point where all the energy input is radiated away.

  5. Observations Of Particle Acceleration In The Blast Waves Of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Curran, Peter A.; van der Horst, A. J.; Evans, P. A.

    2010-03-01

    The electron energy distribution index, p, is a fundamental parameter of the process by which electrons are accelerated to relativistic speeds and by which they radiate, via synchrotron emission. This acceleration process is applicable to a myriad of astronomical sources, from jet sources such as AGN, X-ray binaries and gamma-ray bursts, to particle acceleration in the solar wind and supernovae, and the acceleration of cosmic rays. The accurate measurement of the distribution of p is of fundamental importance to differentiate between the possible theories of electron acceleration at any relativistic shock front. There is division as to whether the electron energy distribution index has a universal value or whether it has a distribution, and if so, what that distribution is. In this presentation we examine one such source of synchrotron emission: the blast waves of gamma-ray bursts. Using our unique Monte Carlo method, we examine the constraints placed on the distribution of p by the observed spectral indices of gamma-ray bursts and parametrize the distribution. We find that the observed distribution of spectral indices is inconsistent with a discrete value of p, but consistent with a Gaussian distribution centred at p 2.4 and having a width of 0.6. This finding rules out the theoretical work that argues for a single, universal value of p, but also demonstrates that the width of the distribution is not as wide as has been suggested by some authors.

  6. Moving shocks through metallic grids: their interaction and potential for blast wave mitigation

    NASA Astrophysics Data System (ADS)

    Andreopoulos, Y.; Xanthos, S.; Subramaniam, K.

    2007-07-01

    Numerical simulations and laboratory measurements have been used to illuminate the interaction of a moving shock wave impacting on metallic grids at various shock strengths and grid solidities. The experimental work was carried out in a large scale shock tube facility while computational work simulated the flow field with a time-dependent inviscid and a time-dependent viscous model. The pressure drop measured across the grids is a result of two phenomena which are associated with the impact of the shock on the metallic grids. First are the reflection and refraction of the incoming shock on the grid itself. This appears to be the main inviscid mechanism associated with the reduction of the strength of the transmitted shock. Second, viscous phenomena are present during the reflection and refraction of the wave as well as during the passage of the induced flow of the air through the grid. The experimental data of pressure drop across the grid obtained in the present investigation are compared with those obtained from computations. The numerical results slightly overpredict the experimental data of relative pressure drop which increases substantially with grid solidity at fixed flow Mach numbers. The processes of shock reflection and refraction are continuous and they can be extended in duration by using thicker grids that will result in lower compression rates of the structural loading and increase the viscous losses associated with these phenomena which will further attenuate the impacting shock. Preliminary theoretical analysis suggests that the use of a graded porosity/solidity material will result in higher pressure drop than a constant porosity/solidity material and thus provide effective blast mitigation.

  7. Quantum and classical dynamics in adiabatic computation

    NASA Astrophysics Data System (ADS)

    Crowley, P. J. D.; Äńurić, T.; Vinci, W.; Warburton, P. A.; Green, A. G.

    2014-10-01

    Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing—though inconclusive—results.

  8. Blast Wave Exposure to the Extremities Causes Endothelial Activation and Damage.

    PubMed

    Spear, Abigail M; Davies, Emma M; Taylor, Christopher; Whiting, Rachel; Macildowie, Sara; Kirkman, Emrys; Midwinter, Mark; Watts, Sarah A

    2015-11-01

    Extremity injury is a significant burden to those injured in explosive incidents and local ischaemia can result in poor functionality in salvaged limbs. This study examined whether blast injury to a limb resulted in a change in endothelial phenotype leading to changes to the surrounding tissue.The hind limbs of terminally anaesthetized rabbits were subjected to one of four blast exposures (high, medium, low, or no blast). Blood samples were analyzed for circulating endothelial cells pre-injury and at 1, 6, and 11 h postinjury as well as analysis for endothelial activation pre-injury and at 1, 6, and 12  h postinjury. Post-mortem tissue (12  h post-injury) was analysed for both protein and mRNA expression and also for histopathology. The high blast group had significantly elevated levels of circulating endothelial cells 6  h postinjury. This group also had significantly elevated tissue mRNA expression of IL-6, E-selection, TNF-α, HIF-1, thrombomodulin, and PDGF. There was a significant correlation between blast dose and the degree of tissue pathology (hemorrhage, neutrophil infiltrate, and oedema) with the worst scores in the high blast group. This study has demonstrated that blast injury can activate the endothelium and in some cases cause damage that in turn leads to pathological changes in the surrounding tissue. For the casualty injured by an explosion the damaging effects of hemorrhage and shock could be exacerbated by blast injury and vice versa so that even low levels of blast become damaging, all of which could affect tissue functionality and long-term outcomes.

  9. Blast Wave Exposure to the Extremities Causes Endothelial Activation and Damage

    PubMed Central

    Spear, Abigail M.; Davies, Emma M.; Taylor, Christopher; Whiting, Rachel; Macildowie, Sara; Kirkman, Emrys; Midwinter, Mark; Watts, Sarah A.

    2015-01-01

    ABSTRACT Extremity injury is a significant burden to those injured in explosive incidents and local ischaemia can result in poor functionality in salvaged limbs. This study examined whether blast injury to a limb resulted in a change in endothelial phenotype leading to changes to the surrounding tissue. The hind limbs of terminally anaesthetized rabbits were subjected to one of four blast exposures (high, medium, low, or no blast). Blood samples were analyzed for circulating endothelial cells pre-injury and at 1, 6, and 11 h postinjury as well as analysis for endothelial activation pre-injury and at 1, 6, and 12 h postinjury. Post-mortem tissue (12 h post-injury) was analysed for both protein and mRNA expression and also for histopathology. The high blast group had significantly elevated levels of circulating endothelial cells 6 h postinjury. This group also had significantly elevated tissue mRNA expression of IL-6, E-selectin, TNF-α, HIF-1, thrombomodulin, and PDGF. There was a significant correlation between blast dose and the degree of tissue pathology (hemorrhage, neutrophil infiltrate, and oedema) with the worst scores in the high blast group. This study has demonstrated that blast injury can activate the endothelium and in some cases cause damage that in turn leads to pathological changes in the surrounding tissue. For the casualty injured by an explosion the damaging effects of hemorrhage and shock could be exacerbated by blast injury and vice versa so that even low levels of blast become damaging, all of which could affect tissue functionality and long-term outcomes. PMID:26418548

  10. The Effect of Initial Conditions on the Nonlinear Evolution of Perturbed Interfaces Driven by Strong Blast Waves

    SciTech Connect

    Miles, Aaron R.

    2004-01-01

    In core-collapse supernovae, strong blast waves drive interfaces susceptible to Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM), and Kelvin-Helmholtz (KH) instabilities. In addition, perturbation growth can result from material expansion in large-scale velocity gradients behind the shock front. Laser-driven experiments are designed to produce a strongly shocked interface whose evolution is a scaled version of the unstable hydrogen-helium interface in core-collapse supernovae such as SN 1987A. The ultimate goal of this research is to develop an understanding of the effect of hydrodynamic instabilities and the resulting transition to turbulence on supernovae observables that remain as yet unexplained. In this dissertation, we present a computational study of unstable systems driven by high Mach number shock and blast waves. Using multi-physics radiation hydrodynamics codes and theoretical models, we consider the late nonlinear instability evolution of single mode, few mode, and multimode interfaces. We rely primarily on 2D calculations but present recent 3D results as well. For planar multimode systems, we show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions (IC's) by allowing for memory of the initial conditions to be retained in the mix-width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. Aspects of the IC's are shown to have a strong effect on the time to transition to the quasi-self-similar regime. With higher-dimensional blast waves, divergence restores the properties necessary for establishment of the self-similar state, but achieving it requires very high initial characteristic mode number and high Mach number for the incident blast wave. We point to recent stellar calculations that predict IC's we find incompatible with self-similarity, and emphasize the

  11. A ceramic damage model for analyses of multi-layered ceramic-core sandwich panels under blast wave pressure loading

    NASA Astrophysics Data System (ADS)

    Lee, Keejoo

    2005-11-01

    A damage model for ceramic materials is developed and incorporated into the geometrically nonlinear solid shell element formulation for dynamic analyses of multi-layered ceramic armor panels under blast wave pressure loading. The damage model takes into account material behaviors observed from multi-axial dynamic tests on Aluminum Nitride (AlN) ceramic. The ceramic fails in a brittle or gradual fashion, depending upon the hydrostatic pressure and applied strain-rate. In the model, the gradual failure is represented by two states: the initial and final failure states. These states are described by two separate failure surfaces that are pressure-dependent and strain-rate-dependent. A scalar damage parameter is defined via using the two failure surfaces, based on the assumption that the local stress state determines material damage and its level. In addition, the damage model accounts for the effect of existing material damage on the new damage. The multi-layered armor panel of interest is comprised of an AlN-core sandwich with unidirectional composite skins and a woven composite back-plate. To accommodate the material damage effect of composite layers, a composite failure model in the open literature is adopted and modified into two separate failure models to address different failure mechanisms of the unidirectional and woven composites. In addition, the effect of strain-rates on the material strengths is incorporated into the composite failure models. For finite element modeling, multiple eighteen-node elements are used in the thickness direction to properly describe mechanics of the multi-layered panel. Dynamic analyses of a multi-layered armor panel are conducted under blast wave pressure loadings. The resulting dynamic responses of the panel demonstrate that dynamic analyses that do not take into account material damage and failure significantly under-predict the peak displacement. The under-prediction becomes more pronounced as the blast load level increases

  12. Microsecond evolution of laser driven blast waves, the influence of shock asymmetries and the resulting development of magnetic fields

    NASA Astrophysics Data System (ADS)

    Tubman, Eleanor; Crowston, R.; Lam, G.; Dimoline, G.; Alraddadi, R.; Doyle, H.; Meinecke, J.; Cross, J.; Bolis, R.; Lamb, D.; Tzeferacos, P.; Doria, D.; Reville, B.; Ahmed, H.; Borghesi, M.; Gregori, G.; Woolsey, N.

    2015-11-01

    The ability to recreate scaled conditions of a supernova remnant within a laboratory environment is of great interest for informing the understanding of the evolution of galactic magnetic fields. The experiments rely on a near point explosion driven by one sided laser illumination producing a plasma, surrounded by a background gas. The subsequent shock and blast waves emerge following an initial ballistic phase into a self-similar expansion. Studies have been undertaken into the evolution of shock asymmetries which lead to magnetic field generation via the Biermann battery mechanism. Here we use the Vulcan laser facility, with targets such as carbon rods and plastic spheres placed in ambient gases of argon, helium or hydrogen, to produce the blast waves. These conditions allow us to study the asymmetries of the shocks using multi-frame imaging cameras, interferometry, and spectroscopy, while measuring the resulting magnetic fields with B-dot probes. The velocity of the shock and the temporal resolution of the asymmetries can be acquired on a single shot by the multi-framing cameras, and comparison with the measured B-dot fields allow for detailed inferences to be made.

  13. KANTBP 2.0: New version of a program for computing energy levels, reaction matrix and radial wave functions in the coupled-channel hyperspherical adiabatic approach

    NASA Astrophysics Data System (ADS)

    Chuluunbaatar, O.; Gusev, A. A.; Vinitsky, S. I.; Abrashkevich, A. G.

    2008-11-01

    A FORTRAN 77 program for calculating energy values, reaction matrix and corresponding radial wave functions in a coupled-channel approximation of the hyperspherical adiabatic approach is presented. In this approach, a multi-dimensional Schrödinger equation is reduced to a system of the coupled second-order ordinary differential equations on a finite interval with homogeneous boundary conditions: (i) the Dirichlet, Neumann and third type at the left and right boundary points for continuous spectrum problem, (ii) the Dirichlet and Neumann type conditions at left boundary point and Dirichlet, Neumann and third type at the right boundary point for the discrete spectrum problem. The resulting system of radial equations containing the potential matrix elements and first-derivative coupling terms is solved using high-order accuracy approximations of the finite element method. As a test desk, the program is applied to the calculation of the reaction matrix and radial wave functions for 3D-model of a hydrogen-like atom in a homogeneous magnetic field. This version extends the previous version 1.0 of the KANTBP program [O. Chuluunbaatar, A.A. Gusev, A.G. Abrashkevich, A. Amaya-Tapia, M.S. Kaschiev, S.Y. Larsen, S.I. Vinitsky, Comput. Phys. Commun. 177 (2007) 649-675]. Program summaryProgram title: KANTBP Catalogue identifier: ADZH_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZH_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 20 403 No. of bytes in distributed program, including test data, etc.: 147 563 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: This depends on the

  14. Macro-mechanical modeling of blast-wave mitigation in foams. Part III: verification of the models

    NASA Astrophysics Data System (ADS)

    Britan, A.; Shapiro, H.; Liverts, M.; Ben-Dor, G.

    2014-05-01

    Three different approaches to macro-mechanical modeling of blast-wave mitigation in foam namely: the single-phase effective gas flow model, the two-phase mixture model and the single bubble/shock wave interaction model are critically reviewed. The nature and extent of the approximations inherent in the formulation of the first two models were examined in Part I of this study. In this part, the applicability of the aforementioned approaches is verified based on a comparison of experimental pressure records obtained in shock tube tests with the results of numerical predictions that used the models under consideration. Deficiencies and inconsistencies that are found during this comparison are clarified and possible improvements are suggested. It is emphasized that both the single-phase and the two-phase approaches predict well the refraction of the incident shock at the air/foam interface while they do not uniquely determine the relaxation process and the shape of the transmitted shock wave front. Various flexibilities that are exploited to better describe the inter-phase interactions do not improve the results significantly. The single bubble model is examined with particular attention paid to the manner in which it predicts the shape of the shock wave front. Connections between the flow viscosity and the transient dynamics of the bubble compression that occur at scales of the shock wave front thickness are explored.

  15. Accidental head explosion: an unusual blast wave injury as a result of self-made fireworks.

    PubMed

    Kunz, S N; Zinka, B; Peschel, O; Fieseler, S

    2011-07-15

    A 33-year old hobby pyrotechnician sustained a lethal craniofacial trauma secondary to a salute fireworks blast. He was examining a misfire of a self-constructed salute gun, when it detonated, causing an explosively rupture of his forehead, which led to his immediate death. An autopsy was performed to achieve knowledge of the injury and to be able to reconstruct the events that lead to it. The pressure effect of the explosion caused a shredded rupture of the forehead with a regional spread of brain tissue and small polygonal skull fragments up to 30m from the detonation site. Furthermore multiple cinderlike fragments of black powder were embedded in the skin of the face and the anterior aspect of the neck (s.c. blast tattoo). The complete destruction of the forehead in combination with the multiple blast tattooing suggested that the explosion detonated while he was leaning over the device.

  16. Biomechanical modeling for the response of human thorax to blast waves

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Tao, Gang

    2015-08-01

    A simplified finite element model of a human thorax had been developed for probing into the mechanical response in simple and complex blast environments. The human thorax model was first created by CT images with blast loading applied via a coupled arbitrary Lagrangian-Eulerian method, allowing for a variety of loads to be considered. The goal is to analyze the maximum stress distributions of lung tissue and peak inward thorax wall velocity and to know the possible regions and levels of lung injury. In parallel, a mathematical model has been modified from the Lobdell model to investigate the detailed percentage of lung injury at each level. The blast loadings around the human thorax were obtained from the finite element model, and were then applied in the mathematical model as the boundary conditions to predict the normalized work of the human thorax lung. The present results are found in agreement with the modified Bowen curves and the results predicted by Axelsson's model.

  17. Skull flexure from blast waves: a mechanism for brain injury with implications for helmet design

    SciTech Connect

    Moss, W C; King, M J; Blackman, E G

    2009-04-14

    Traumatic brain injury [TBI] has become a signature injury of current military conflicts. The debilitating effects of TBI are long-lasting and costly. Although the mechanisms by which impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. Various possibilities have been investigated, but blast-induced deformation of the skull has been neglected. From numerical hydrodynamic simulations, we have discovered that nonlethal blasts can induce sufficient flexure of the skull to generate potentially damaging loads in the brain, even if no impact occurs. The possibility that this mechanism may contribute to TBI has implications for the diagnosis of soldiers and the design of protective equipment such as helmets.

  18. Accidental head explosion: an unusual blast wave injury as a result of self-made fireworks.

    PubMed

    Kunz, S N; Zinka, B; Peschel, O; Fieseler, S

    2011-07-15

    A 33-year old hobby pyrotechnician sustained a lethal craniofacial trauma secondary to a salute fireworks blast. He was examining a misfire of a self-constructed salute gun, when it detonated, causing an explosively rupture of his forehead, which led to his immediate death. An autopsy was performed to achieve knowledge of the injury and to be able to reconstruct the events that lead to it. The pressure effect of the explosion caused a shredded rupture of the forehead with a regional spread of brain tissue and small polygonal skull fragments up to 30m from the detonation site. Furthermore multiple cinderlike fragments of black powder were embedded in the skin of the face and the anterior aspect of the neck (s.c. blast tattoo). The complete destruction of the forehead in combination with the multiple blast tattooing suggested that the explosion detonated while he was leaning over the device. PMID:21570222

  19. Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

    NASA Astrophysics Data System (ADS)

    Moss, William C.; King, Michael J.; Blackman, Eric G.

    2009-09-01

    Traumatic brain injury (TBI) has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that nonlethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

  20. Skull flexure from blast waves: a mechanism for brain injury with implications for helmet design.

    PubMed

    Moss, William C; King, Michael J; Blackman, Eric G

    2009-09-01

    Traumatic brain injury (TBI) has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that nonlethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design. PMID:19792349

  1. Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

    SciTech Connect

    Moss, W C; King, M J; Blackman, E G

    2009-04-30

    Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

  2. Isothermal and Adiabatic Measurements.

    ERIC Educational Resources Information Center

    McNairy, William W.

    1996-01-01

    Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)

  3. Versatile gas gun target assembly for studying blast wave mitigation in materials

    NASA Astrophysics Data System (ADS)

    Bartyczak, S.; Mock, W., Jr.

    2012-03-01

    Traumatic brain injury (TBI) has become a serious problem for military personnel returning from recent conflicts. This has increased interest in investigating blast mitigating materials for use in helmets. In this paper we describe a new versatile target assembly that is used with an existing gas gun for studying these materials.

  4. The role of stress waves in thoracic visceral injury from blast loading: modification of stress transmission by foams and high-density materials.

    PubMed

    Cooper, G J; Townend, D J; Cater, S R; Pearce, B P

    1991-01-01

    Materials have been applied to the thoracic wall of anaesthetised experimental animals exposed to blast overpressure to investigate the coupling of direct stress waves into the thorax and the relative contribution of compressive stress waves and gross thoracic compression to lung injury. The ultimate purpose of the work is to develop effective personal protection from the primary effects of blast overpressure--efficient protection can only be achieved if the injury mechanism is identified and characterized. Foam materials acted as acoustic couplers and resulted in a significant augmentation of the visceral injury; decoupling and elimination of injury were achieved by application of a high acoustic impedance layer on top of the foam. In vitro experiments studying stress wave transmission from air through various layers into an anechoic water chamber showed a significant increase in power transmitted by the foams, principally at high frequencies. Material such as copper or resin bonded Kevlar incorporated as a facing upon the foam achieved substantial decoupling at high frequencies--low frequency transmission was largely unaffected. An acoustic transmission model replicated the coupling of the blast waves into the anechoic water chamber. The studies suggest that direct transmission of stress waves plays a dominant role in lung parenchymal injury from blast loading and that gross thoracic compression is not the primary injury mechanism. Acoustic decoupling principles may therefore be employed to reduce the direct stress coupled into the body and thus reduce the severity of lung injury--the most simple decoupler is a high acoustic impedance material as a facing upon a foam, but decoupling layers may be optimized using acoustic transmission models. Conventional impacts producing high body wall velocities will also lead to stress wave generation and transmission--stress wave effects may dominate the visceral response to the impact with direct compression and shear

  5. KANTBP: A program for computing energy levels, reaction matrix and radial wave functions in the coupled-channel hyperspherical adiabatic approach

    NASA Astrophysics Data System (ADS)

    Chuluunbaatar, O.; Gusev, A. A.; Abrashkevich, A. G.; Amaya-Tapia, A.; Kaschiev, M. S.; Larsen, S. Y.; Vinitsky, S. I.

    2007-10-01

    A FORTRAN 77 program is presented which calculates energy values, reaction matrix and corresponding radial wave functions in a coupled-channel approximation of the hyperspherical adiabatic approach. In this approach, a multi-dimensional Schrödinger equation is reduced to a system of the coupled second-order ordinary differential equations on the finite interval with homogeneous boundary conditions of the third type. The resulting system of radial equations which contains the potential matrix elements and first-derivative coupling terms is solved using high-order accuracy approximations of the finite-element method. As a test desk, the program is applied to the calculation of the energy values and reaction matrix for an exactly solvable 2D-model of three identical particles on a line with pair zero-range potentials. Program summaryProgram title: KANTBP Catalogue identifier: ADZH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 4224 No. of bytes in distributed program, including test data, etc.: 31 232 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: depends on (a) the number of differential equations; (b) the number and order of finite-elements; (c) the number of hyperradial points; and (d) the number of eigensolutions required. Test run requires 30 MB Classification: 2.1, 2.4 External routines: GAULEG and GAUSSJ [W.H. Press, B.F. Flanery, S.A. Teukolsky, W.T. Vetterley, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, Cambridge, 1986] Nature of problem: In the hyperspherical adiabatic

  6. Wireless adiabatic power transfer

    SciTech Connect

    Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.

    2011-03-15

    Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

  7. Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Dwek, Eliahu; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, John; DeBuizer James M.; Gehrz, Robert D.; Kirshner, Robert P.; McCray, Richard; Park, Sangwok; Polomski, Elisha; Woodward, Charles

    2007-01-01

    Multiwavelength observations of supernova remnant (SNR) 1987A show that its morphology and luminosity are rapidly changing at X-ray, optical, infrared, and radio wavelengths as the blast wave from the explosion expands into the circumstellar equatorial ring, produced by mass loss from the progenitor star. The observed infrared (IR) radiation arises from the interaction of dust grains that formed in mass outflow with the soft X-ray emitting plasma component of the shocked gas. Spitzer IRS spectra at 5 - 30 microns taken on day 6190 since the explosion show that the emission arises from approx. 1.1 x 10(exp -6) solar mass of silicate grains radiating at a temperature of approx. 180+/-(15-20) K. Subsequent observations on day 7137 show that the IR flux had increased by a factor of 2 while maintaining an almost identical spectral shape. The observed IR-to-X-ray flux ratio (IRX) is consistent with that of a dusty plasma with standard LMC dust abundances. This flux ratio has decreased by a factor of approx. 2 between days 6190 and 7137, providing the first direct observation of the ongoing destruction of dust in an expanding SN blast wave on dynamic time scales. Detailed models consistent with the observed dust temperature, the ionization fluence of the soft X-ray emission component, and the evolution of IRX suggest that the radiating si1icate grains are immersed in a 3.5 x 10(exp 6) K plasma with a density of (0.3 - 1) x 10(exp 4)/cu cm, and have a size distribution that is confined to a narrow range of radii between 0.02 and 0.2 microns. Smaller grains may have been evaporated by the initial UV flash from the supernova.

  8. Existence and stability of alternative ion-acoustic solitary wave solution of the combined MKdV-KdV-ZK equation in a magnetized nonthermal plasma consisting of warm adiabatic ions

    SciTech Connect

    Das, Jayasree; Bandyopadhyay, Anup; Das, K. P.

    2007-09-15

    The purpose of this paper is to present the recent work of Das et al. [J. Plasma Phys. 72, 587 (2006)] on the existence and stability of the alternative solitary wave solution of fixed width of the combined MKdV-KdV-ZK (Modified Korteweg-de Vries-Korteweg-de Vries-Zakharov-Kuznetsov) equation for the ion-acoustic wave in a magnetized nonthermal plasma consisting of warm adiabatic ions in a more generalized form. Here we derive the alternative solitary wave solution of variable width instead of fixed width of the combined MKdV-KdV-ZK equation along with the condition for its existence and find that this solution assumes the sech profile of the MKdV-ZK (Modified Korteweg-de Vries-Zakharov-Kuznetsov) equation, when the coefficient of the nonlinear term of the KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equation tends to zero. The three-dimensional stability analysis of the alternative solitary wave solution of variable width of the combined MKdV-KdV-ZK equation shows that the instability condition and the first order growth rate of instability are exactly the same as those of the solitary wave solution (the sech profile) of the MKdV-ZK equation, when the coefficient of the nonlinear term of the KdV-ZK equation tends to zero.

  9. Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics

    NASA Astrophysics Data System (ADS)

    Albert, Julian; Kaiser, Dustin; Engel, Volker

    2016-05-01

    Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.

  10. Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics.

    PubMed

    Albert, Julian; Kaiser, Dustin; Engel, Volker

    2016-05-01

    Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.

  11. Measurements of blast waves from bursting frangible spheres pressurized with flash-evaporation vapor or liquid

    NASA Technical Reports Server (NTRS)

    Esparaza, E. D.; Baker, W. E.

    1977-01-01

    Incident overpressure data from frangible spheres pressurized with a flash-evaporating fluid in liquid and vapor form were obtained in laboratory experiments. Glass spheres under higher than ambient internal pressure of Freon-12 were purposely burst to obtain time histories of overpressure. Nondimensional peak pressures, arrival and duration times, and impulses are presented, and whenever possible plotted and compared with compiled data for Pentolite high-explosive. The data are generally quite repeatable and show differences from blast data produced by condensed high-explosives.

  12. Parallelizable adiabatic gate teleportation

    NASA Astrophysics Data System (ADS)

    Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio

    2015-12-01

    To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic

  13. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of rho and Structure of the Circumburst Medium

    NASA Technical Reports Server (NTRS)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.

    2008-01-01

    We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 < k < 1, consistent with a homogeneous circumburst medium.

  14. Role of helmet in the mechanics of shock wave propagation under blast loading conditions.

    PubMed

    Ganpule, S; Gu, L; Alai, A; Chandra, N

    2012-01-01

    The effectiveness of helmets in extenuating the primary shock waves generated by the explosions of improvised explosive devices is not clearly understood. In this work, the role of helmet on the overpressurisation and impulse experienced by the head were examined. The shock wave-head interactions were studied under three different cases: (i) unprotected head, (ii) head with helmet but with varying head-helmet gaps and (iii) head covered with helmet and tightly fitting foam pads. The intensification effect was discussed by examining the shock wave flow pattern and verified with experiments. A helmet with a better protection against shock wave is suggested. PMID:21806412

  15. Accurate adiabatic correction in the hydrogen molecule

    NASA Astrophysics Data System (ADS)

    Pachucki, Krzysztof; Komasa, Jacek

    2014-12-01

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10-12 at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10-7 cm-1, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

  16. Accurate adiabatic correction in the hydrogen molecule

    SciTech Connect

    Pachucki, Krzysztof; Komasa, Jacek

    2014-12-14

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

  17. Accurate adiabatic correction in the hydrogen molecule.

    PubMed

    Pachucki, Krzysztof; Komasa, Jacek

    2014-12-14

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10(-12) at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10(-7) cm(-1), which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels. PMID:25494728

  18. Adiabatic capture and debunching

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2012-03-01

    In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.

  19. Adiabatic gate teleportation.

    PubMed

    Bacon, Dave; Flammia, Steven T

    2009-09-18

    The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.

  20. Adiabatically implementing quantum gates

    SciTech Connect

    Sun, Jie; Lu, Songfeng Liu, Fang

    2014-06-14

    We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.

  1. Entanglement and adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Ahrensmeier, D.

    2006-06-01

    Adiabatic quantum computation provides an alternative approach to quantum computation using a time-dependent Hamiltonian. The time evolution of entanglement during the adiabatic quantum search algorithm is studied, and its relevance as a resource is discussed.

  2. Magnetic field generation and diffusion by a laser-produced blast wave propagating in non-homogenous plasma

    NASA Astrophysics Data System (ADS)

    Marocchino, A.; Atzeni, S.; Schiavi, A.

    2015-04-01

    In this paper we discuss the magnetic field self generation, via the so-called Biermann battery effect, and its diffusion for a blast wave (BW) expanding in a perturbed background medium. A series of simulations verify the bi-linear behavior of the Biermann battery source term both in amplitude and in wavenumber. Such a behavior is valid in the limit of no diffusivity. When diffusivity is also considered, we observe an inverse proportionality with the wavenumber: for large wavenumber perturbation magnetic diffusivity plays a key role. Writing the induction equation in a dimensionless form we discuss how, in terms of magnetic properties, the BW can be subdivided into three main regions: the remnant where the frozen-in-flow approximation holds, the thin shell where the magnetic field is in fact generated but at the same time begins to diffuse, and the shock front where the magnetic field diffuses away. A possible experimental scenario that could induce magnetic fields of about 100 gauss is finally investigated. Simulations have been performed with the code DUED.

  3. Observation and modeling of mixing-layer development in high-energy-density, blast-wave-driven shear flow

    SciTech Connect

    Di Stefano, C. A. Kuranz, C. C.; Klein, S. R.; Drake, R. P.; Malamud, G.; Henry de Frahan, M. T.; Johnsen, E.; Shimony, A.; Shvarts, D.; Smalyuk, V. A.; Martinez, D.

    2014-05-15

    In this work, we examine the hydrodynamics of high-energy-density (HED) shear flows. Experiments, consisting of two materials of differing density, use the OMEGA-60 laser to drive a blast wave at a pressure of ∼50 Mbar into one of the media, creating a shear flow in the resulting shocked system. The interface between the two materials is Kelvin-Helmholtz unstable, and a mixing layer of growing width develops due to the shear. To theoretically analyze the instability's behavior, we rely on two sources of information. First, the interface spectrum is well-characterized, which allows us to identify how the shock front and the subsequent shear in the post-shock flow interact with the interface. These observations provide direct evidence that vortex merger dominates the evolution of the interface structure. Second, simulations calibrated to the experiment allow us to estimate the time-dependent evolution of the deposition of vorticity at the interface. The overall result is that we are able to choose a hydrodynamic model for the system, and consequently examine how well the flow in this HED system corresponds to a classical hydrodynamic description.

  4. Diffusion of cosmic rays in a multiphase interstellar medium swept-up by a supernova remnant blast wave

    NASA Astrophysics Data System (ADS)

    Roh, Soonyoung; Inutsuka, Shu-ichiro; Inoue, Tsuyoshi

    2016-01-01

    Supernova remnants (SNRs) are one of the most energetic astrophysical events and are thought to be the dominant source of Galactic cosmic rays (CRs). A recent report on observations from the Fermi satellite has shown a signature of pion decay in the gamma-ray spectra of SNRs. This provides strong evidence that high-energy protons are accelerated in SNRs. The actual gamma-ray emission from pion decay should depend on the diffusion of CRs in the interstellar medium. In order to quantitatively analyse the diffusion of high-energy CRs from acceleration sites, we have performed test particle numerical simulations of CR protons using a three-dimensional magnetohydrodynamics (MHD) simulation of an interstellar medium swept-up by a blast wave. We analyse the diffusion of CRs at a length scale of order a few pc in our simulated SNR, and find the diffusion of CRs is precisely described by a Bohm diffusion, which is required for efficient acceleration at least for particles with energies above 30 TeV for a realistic interstellar medium. Although we find the possibility of a superdiffusive process (travel distance ∝ t0.75) in our simulations, its effect on CR diffusion at the length scale of the turbulence in the SNR is limited.

  5. Transition to Turbulence and Effect of Initial Conditions on 3D Compressible Mixing in Planar Blast-wave-driven Systems

    SciTech Connect

    Miles, A R; Edwards, M J; Greenough, J A

    2004-11-08

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams, 9(2), 209 (1991)] are presented. Using the multi-physics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J.A. Greenough, J. Comp. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pre-transition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernova are discussed.

  6. Blood brain barrier dysfunction and delayed neurological deficits in mild traumatic brain injury induced by blast shock waves

    PubMed Central

    Shetty, Ashok K.; Mishra, Vikas; Kodali, Maheedhar; Hattiangady, Bharathi

    2014-01-01

    Mild traumatic brain injury (mTBI) resulting from exposure to blast shock waves (BSWs) is one of the most predominant causes of illnesses among veterans who served in the recent Iraq and Afghanistan wars. Such mTBI can also happen to civilians if exposed to shock waves of bomb attacks by terrorists. While cognitive problems, memory dysfunction, depression, anxiety and diffuse white matter injury have been observed at both early and/or delayed time-points, an initial brain pathology resulting from exposure to BSWs appears to be the dysfunction or disruption of the blood-brain barrier (BBB). Studies in animal models suggest that exposure to relatively milder BSWs (123 kPa) initially induces free radical generating enzymes in and around brain capillaries, which enhances oxidative stress resulting in loss of tight junction (TJ) proteins, edema formation, and leakiness of BBB with disruption or loss of its components pericytes and astrocyte end-feet. On the other hand, exposure to more intense BSWs (145–323 kPa) causes acute disruption of the BBB with vascular lesions in the brain. Both of these scenarios lead to apoptosis of endothelial and neural cells and neuroinflammation in and around capillaries, which may progress into chronic traumatic encephalopathy (CTE) and/or a variety of neurological impairments, depending on brain regions that are afflicted with such lesions. This review discusses studies that examined alterations in the brain milieu causing dysfunction or disruption of the BBB and neuroinflammation following exposure to different intensities of BSWs. Furthermore, potential of early intervention strategies capable of easing oxidative stress, repairing the BBB or blocking inflammation for minimizing delayed neurological deficits resulting from exposure to BSWs is conferred. PMID:25165433

  7. Blood brain barrier dysfunction and delayed neurological deficits in mild traumatic brain injury induced by blast shock waves.

    PubMed

    Shetty, Ashok K; Mishra, Vikas; Kodali, Maheedhar; Hattiangady, Bharathi

    2014-01-01

    Mild traumatic brain injury (mTBI) resulting from exposure to blast shock waves (BSWs) is one of the most predominant causes of illnesses among veterans who served in the recent Iraq and Afghanistan wars. Such mTBI can also happen to civilians if exposed to shock waves of bomb attacks by terrorists. While cognitive problems, memory dysfunction, depression, anxiety and diffuse white matter injury have been observed at both early and/or delayed time-points, an initial brain pathology resulting from exposure to BSWs appears to be the dysfunction or disruption of the blood-brain barrier (BBB). Studies in animal models suggest that exposure to relatively milder BSWs (123 kPa) initially induces free radical generating enzymes in and around brain capillaries, which enhances oxidative stress resulting in loss of tight junction (TJ) proteins, edema formation, and leakiness of BBB with disruption or loss of its components pericytes and astrocyte end-feet. On the other hand, exposure to more intense BSWs (145-323 kPa) causes acute disruption of the BBB with vascular lesions in the brain. Both of these scenarios lead to apoptosis of endothelial and neural cells and neuroinflammation in and around capillaries, which may progress into chronic traumatic encephalopathy (CTE) and/or a variety of neurological impairments, depending on brain regions that are afflicted with such lesions. This review discusses studies that examined alterations in the brain milieu causing dysfunction or disruption of the BBB and neuroinflammation following exposure to different intensities of BSWs. Furthermore, potential of early intervention strategies capable of easing oxidative stress, repairing the BBB or blocking inflammation for minimizing delayed neurological deficits resulting from exposure to BSWs is conferred. PMID:25165433

  8. Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.

    PubMed

    Wang, Junjie; Wang, Meng; Xu, Jian; Peng, Li; Yang, Minghong; Xia, Minghe; Jiang, Desheng

    2014-10-01

    This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55 MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767 μs. Finally, three aspects that need further study for practical use are pointed out.

  9. Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.

    PubMed

    Wang, Junjie; Wang, Meng; Xu, Jian; Peng, Li; Yang, Minghong; Xia, Minghe; Jiang, Desheng

    2014-10-01

    This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55 MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767 μs. Finally, three aspects that need further study for practical use are pointed out. PMID:25322237

  10. Adiabatic topological quantum computing

    NASA Astrophysics Data System (ADS)

    Cesare, Chris; Landahl, Andrew J.; Bacon, Dave; Flammia, Steven T.; Neels, Alice

    2015-07-01

    Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here, we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.

  11. Adiabatic invariant value variation under shortwave band subcritical conditions

    NASA Astrophysics Data System (ADS)

    Svistunov, K. V.; Tinin, M. V.

    1985-04-01

    The possibility of significant variations of the adiabatic invariant is examined for the propagation of radio waves in an irregular Earth-ionosphere waveguide with a parabolic dependence of permittivity on height. Numerical and analytical results indicate that nonexponential deviations of the adiabatic invariant can occur not only when the characteristic size of horizontal irregularity decreases (e.g., during resonant beam excitation) but also in quasi-critical conditions and for smoothly irregular waveguides.

  12. Reflection and Diffraction Phenomena of Blast Wave Propagation in Nuclear Fuel Cycle Facility

    NASA Astrophysics Data System (ADS)

    Miura, Akihiko; Matsuo, Akiko; Mizukaki, Toshiharu; Shiraishi, Takuya; Utsunomiya, Go; Takayama, Kazuyoshi; Nojiri, Ichiro

    This paper presents the results of an optical experiment which is carried out to measure the pressure and to observe the wave propagations when an explosion occurs in a model of a nuclear facility for preventing and mitigating the serious damage of nuclear facility. Numerical simulation is also performed to compare the phenomena in a model of nuclear facility. Nuclear facility is simulated as the several closed rooms in these experiments and simulations, because the nuclear facility is composed of many closed rooms. As a result, typical tendencies of pressure history are obtained, and it is confirmed that the explosion which occurs in a closed space is reflected in the complexity at the walls and interfered mutually with progressing waves. Finally, experimental results are compared with a numerical simulation. It is confirmed that the results of a numerical simulation show a good agreement with experimental results.

  13. Laboratory observation of secondary shock formation ahead of a strongly radiative blast wave

    SciTech Connect

    Hansen, J F; Edwards, M J; Froula, D H; Edens, A D; Gregori, G; Ditmire, T R

    2006-04-20

    We have previously reported the experimental discovery of a second shock forming ahead of a radiative shock propagating in Xe. The initial shock is spherical, radiative, with a high Mach number, and it sends a supersonic radiative heat far ahead of itself. The heat wave rapidly slows to a transonic regime and when its Mach number drops to two with respect to the downstream plasma, the heat wave drives a second shock ahead of itself to satisfy mass and momentum conservation in the heat wave reference frame. We now show experimental data from a range of mixtures of Xe and N{sub 2}, gradually changing the properties of the initial shock and the environment into which the shock moves and radiates (the radiative conductivity and the heat capacity). We have successfully observed second shock formation over the entire range from 100% Xe mass fraction to 100% N{sub 2}. The formation radius of the second shock as a function of Xe mass fraction is consistent with an analytical estimate.

  14. Translational Research for Blast-Induced Traumatic Brain Injury: Injury Mechanism to Development of Medical Instruments

    NASA Astrophysics Data System (ADS)

    Nakagawa, A.; Ohtani, K.; Arafune, T.; Washio, T.; Iwasaki, M.; Endo, T.; Ogawa, Y.; Kumabe, T.; Takayama, K.; Tominaga, T.

    1. Investigation of shock wave-induced phenomenon: blast-induced traumatic brain injury Blast wave (BW) is generated by explosion and is comprised of lead shock wave (SE) followed by subsequent supersonic flow.

  15. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  16. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

    PubMed Central

    Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  17. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

  18. Interaction of a strong blast wave with a free surface. [at ocean surface

    NASA Technical Reports Server (NTRS)

    Falade, A.; Holt, M.

    1978-01-01

    When a point source explosion is initiated at the ocean surface, the shock propagated into the water is reflected at the surface as a centered expansion wave. The solution in the neighborhood of the interaction point is obtained by writing the equations of motion in the appropriate similarity variables and then changing the independent variables to polar coordinates based at the interaction point. From the zero-order solution of the resulting equations the slopes of boundaries at the interaction point are obtained. A first-order perturbation of this solution provides more accurate representation of the flow variables and the curvature of the shock surface near the interaction point.

  19. Initial decay of flow properties of planar, cylindrical and spherical blast waves

    NASA Astrophysics Data System (ADS)

    Sadek, H. S. I.; Gottlieb, J. J.

    1983-10-01

    Analytical expressions are presented for the initial decay of all major flow properties just behind planar, cylindrical, and spherical shock wave fronts whose trajectories are known as a function of either distance versus time or shock overpressure versus distance. These expressions give the time and/or distance derivatives of the flow properties not only along constant time and distance lines but also along positive and negative characteristic lines and a fluid-particle path. Conventional continuity, momentum and energy equations for the nonstationary motion of an inviscid, non-heat conducting, compressible gas are used in their derivation, along with the equation of state of a perfect gas. All analytical expressions are validated by comparing the results to those obtained indirectly from known self-similar solutions for planar, cylindrical and spherical shock-wave flows generated both by a sudden energy release and by a moving piston. Futhermore, time derivatives of pressure and flow velocity are compared to experimental data from trinitrotoluene (TNT), pentolite, ammonium nitrate-fuel oil (ANFO) and propane-oxygen explosions, and good agreement is obtained.

  20. Adiabatic Halo Formation

    SciTech Connect

    Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.

    2005-06-08

    In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.

  1. The laboratory simulation of unmagnetized supernova remnants Absence of a blast wave

    NASA Technical Reports Server (NTRS)

    Borovsky, J. E.; Pongratz, M. B.; Roussel-Dupre, R. A.; Tan, T.-H.

    1984-01-01

    Supernova remnants are experimentally simulated by irradiating spherical targets with eight-beam carbon dioxide laser in a chamber containing finite amounts of neutral gas, the gas being ionized by radiation from the hot target. The expansion velocities of the target plasmas are approximately the same as the expansion velocities of supernova ejecta and the experiment is successfully scaled to the case of a supernova remnant in an unmagnetized, low-density, interstellar medium. No sweep-up of the ambient plasma is detected, indicating that no hydrodynamic shock wave is formed to couple the target ejecta to the ambient gas. The experiment implies that if supernova ejecta couple to the interstellar medium, magnetic-field effects may be crucial to the physical description.

  2. [Blast injuries of the ear].

    PubMed

    Haralampiev, K; Ristić, B

    1991-01-01

    Blast injury of the ear is the actual military medical problem. The ear, due to its anatomo-physiologic characteristics, is more sensitive to effects of blast waves than other organs and systems. The anatomic and functional ear damages, their symptoms, etiology and clinical course are described. The diagnosis and treatment have been pointed out. PMID:1807053

  3. Adiabatic cooling of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Sandbaek, Ornulf; Leer, Egil

    1992-01-01

    In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.

  4. Spatial adiabatic passage: a review of recent progress

    NASA Astrophysics Data System (ADS)

    Menchon-Enrich, R.; Benseny, A.; Ahufinger, V.; Greentree, A. D.; Busch, Th; Mompart, J.

    2016-07-01

    Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound.

  5. Spatial adiabatic passage: a review of recent progress.

    PubMed

    Menchon-Enrich, R; Benseny, A; Ahufinger, V; Greentree, A D; Busch, Th; Mompart, J

    2016-07-01

    Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound. PMID:27245462

  6. Geometry of the Adiabatic Theorem

    ERIC Educational Resources Information Center

    Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas

    2012-01-01

    We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…

  7. Rayleigh-Taylor instabilities in Type Ia supernova remnants undergoing cosmic ray particle acceleration - low adiabatic index solutions

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Yueh

    2011-07-01

    This study investigates the evolution of Rayleigh-Taylor (R-T) instabilities in Type Ia supernova remnants that are associated with a low adiabatic index γ, where γ < 5/3, which reflects the expected change in the supernova shock structure as a result of cosmic ray particle acceleration. Extreme cases, such as the case with the maximum compression ratio that corresponds to γ= 1.1, are examined. As γ decreases, the shock compression ratio rises, and an increasingly narrow intershock region with a more pronounced initial mixture of R-T unstable gas is produced. Consequently, the remnant outline may be perturbed by small-amplitude, small-wavelength bumps. However, as the instability decays over time, the extent of convective mixing in terms of the ratio of the radius of the R-T fingers to the blast wave does not strongly depend on the value of γ for γ≥ 1.2. As a result of the age of the remnant, the unstable gas cannot extend sufficiently far to form metal-enriched filaments of ejecta material close to the periphery of Tycho's supernova remnant. The consistency of the dynamic properties of Tycho's remnant with the adiabatic model γ= 5/3 reveals that the injection of cosmic rays is too weak to alter the shock structure. Even with very efficient acceleration of cosmic rays at the shock, significantly enhanced mixing is not expected in Type Ia supernova remnants.

  8. June 7 Ballistic Blast Results in Solar Tsunami

    NASA Video Gallery

    In addition to the magnificent blast, SDO detected a shadowy shock wave issuing from the blast site on the June 7, 2011 event. The 'solar tsunami' propagated more than halfway across the sun, visib...

  9. Phase avalanches in near-adiabatic evolutions

    SciTech Connect

    Vertesi, T.; Englman, R.

    2006-02-15

    In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.

  10. Energies of GRB blast waves and prompt efficiencies as implied by modelling of X-ray and GeV afterglows

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Duran, Rodolfo Barniol; Piran, Tsvi

    2015-11-01

    We consider a sample of 10 gamma-ray bursts with long-lasting ( ≳ 102 s) emission detected by Fermi/Large Area Telescope and for which X-ray data around 1 d are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average ˜50 times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around 1 d, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: (i) either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow-cooling regime or (ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields (10-6 ≲ ɛB ≲ 10-3) and relatively large isotropic kinetic blast wave energies 10^{53} erg<{E}_{0,kin}<10^{55} erg corresponding to large lower limits on the collimated energies, in the range 10^{52} erg<{E}_{θ ,kin}<5× 10^{52} erg for an ISM (interstellar medium) environment with n ˜ 1 cm-3 and 10^{52} erg<{E}_{θ ,kin}<10^{53} erg for a wind environment with A* ˜ 1. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.

  11. Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, I. John; De Buizer, James M.; Gehrz, Robert D.; Park, Sangwook; Polomski, Elisha F.; Slavin, Jonathan D.; Woodward, Charles E.

    2010-01-01

    We have used the Spitzer satellite to monitor the laid-IR evolution of SN 1987A over a 5 year period spanning the epochs between days 6000 and 8000 since the explosion. The supernova (SN) has evolved into a supernova remnant (SNR) and its radiative output, is dominated by the interaction of the SN blast wave with the pre-existing equatorial ring (ER). The mid-IR spectrum is dominated by emission from approximately 180 K silicate dust, collisionally-heated by the hot X-ray emitting gas with a temperature and density of 5 x 10(exp 6) K and approximately 3 x 10(exp 4) per cubic centimeter, respectively. The mass of the radiating dust is approximately 1.2 x 10(exp -6) solar mass on day 7554, and scales linearly with IR flux. Comparison of the IR data with the soft X-ray flux derived from Chandra observations shows that the IR-to-X-ray flux ratio, IRX, is roughly constant with a value of 2.5. Gas-grain collisions therefore dominate the cooling of the shocked gas. The constancy of IRX is most consistent with the scenario that very little grain processing or gas cooling have occurred throughout this epoch. The shape of the dust spectrum remained unchanged during the observations while the total flux increased by a factor of approximately 5 with a time dependence of t(sup '0.87 plus or minus 0.20), t' being the time since the first encounter between the blast wave and the ER. These observations are consistent with the transitioning of the blast wave from free expansion to a Sedov phase as it propagates into the main body of the ER, as also suggested by X-ray observations. The constant spectral shape of they IR, emission provides strong constraints on the density and temperature of the shocked gas in which the interaction takes place. The IR spectra also suggest the presence of a secondary population of very small, hot (T greater than or equal to 350 K), featureless dust. If these grains spatially coexists with the silicates, then they must have shorter lifetimes. The data

  12. Minimisation of the explosion shock wave load onto the occupants inside the vehicle during trinitrotoluene charge blast.

    PubMed

    Krzystała, Edyta; Mężyk, Arkadiusz; Kciuk, Sławomir

    2016-01-01

    The aim of this study was to elaborate identification method of crew overload as a result of trinitrotoluene charge explosion under the military wheeled vehicle. During the study, an experimental military ground research was carried out. The aim of this research was to verify the mine blast resistance of the prototype wheeled vehicle according to STANG 4569 as well as the anti-explosive seat. Within the work, the original methodology was elaborated along with a prototype research statement. This article presents some results of the experimental research, thanks to which there is a possibility to estimate the crew's lives being endangered in an explosion through the measurement of acceleration as well as the pressure on the chest, head and internal organs. On the basis of our acceleration results, both effectiveness and infallibility of crew protective elements along with a blast mitigation seat were verified. PMID:25307173

  13. Minimisation of the explosion shock wave load onto the occupants inside the vehicle during trinitrotoluene charge blast.

    PubMed

    Krzystała, Edyta; Mężyk, Arkadiusz; Kciuk, Sławomir

    2016-01-01

    The aim of this study was to elaborate identification method of crew overload as a result of trinitrotoluene charge explosion under the military wheeled vehicle. During the study, an experimental military ground research was carried out. The aim of this research was to verify the mine blast resistance of the prototype wheeled vehicle according to STANG 4569 as well as the anti-explosive seat. Within the work, the original methodology was elaborated along with a prototype research statement. This article presents some results of the experimental research, thanks to which there is a possibility to estimate the crew's lives being endangered in an explosion through the measurement of acceleration as well as the pressure on the chest, head and internal organs. On the basis of our acceleration results, both effectiveness and infallibility of crew protective elements along with a blast mitigation seat were verified.

  14. Characteristics of pressure waves

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Air blast characteristics generated by most types of explosions are discussed. Data cover both negative and positive blast load phases and net transverse pressure as a function of time. The effects of partial or total confinement, atmospheric propagation, absorption of energy by ground shock or cratering, and transmission over irregular terrain on blast wave properties were also considered.

  15. Blast Injuries

    MedlinePlus

    ... Service Members & Veterans Family & Caregivers Medical Providers Blast Injuries U.S. Army photo by Sgt. Gustavo Olgiati How ... tertiary injury Does a blast cause different brain injuries than blunt trauma? There currently is no evidence ...

  16. Lattice Boltzmann method for adiabatic acoustics.

    PubMed

    Li, Yanbing; Shan, Xiaowen

    2011-06-13

    The lattice Boltzmann method (LBM) has been proved to be a useful tool in many areas of computational fluid dynamics, including computational aero-acoustics (CAA). However, for historical reasons, its applications in CAA have been largely restricted to simulations of isothermal (Newtonian) sound waves. As the recent kinetic theory-based reformulation establishes a theoretical framework in which LBM can be extended to recover the full Navier-Stokes-Fourier (NS) equations and beyond, in this paper, we show that, at least at the low-frequency limit (sound frequency much less than molecular collision frequency), adiabatic sound waves can be accurately simulated by the LBM provided that the lattice and the distribution function ensure adequate recovery of the full NS equations.

  17. Instability of a planar expansion wave.

    PubMed

    Velikovich, A L; Zalesak, S T; Metzler, N; Wouchuk, J G

    2005-10-01

    An expansion wave is produced when an incident shock wave interacts with a surface separating a fluid from a vacuum. Such an interaction starts the feedout process that transfers perturbations from the rippled inner (rear) to the outer (front) surface of a target in inertial confinement fusion. Being essentially a standing sonic wave superimposed on a centered expansion wave, a rippled expansion wave in an ideal gas, like a rippled shock wave, typically produces decaying oscillations of all fluid variables. Its behavior, however, is different at large and small values of the adiabatic exponent gamma. At gamma > 3, the mass modulation amplitude delta(m) in a rippled expansion wave exhibits a power-law growth with time alpha(t)beta, where beta = (gamma - 3)/(gamma - 1). This is the only example of a hydrodynamic instability whose law of growth, dependent on the equation of state, is expressed in a closed analytical form. The growth is shown to be driven by a physical mechanism similar to that of a classical Richtmyer-Meshkov instability. In the opposite extreme gamma - 1 < 1, delta(m) exhibits oscillatory growth, approximately linear with time, until it reaches its peak value approximately (gamma - 1)(-1/2), and then starts to decrease. The mechanism driving the growth is the same as that of Vishniac's instability of a blast wave in a gas with low . Exact analytical expressions for the growth rates are derived for both cases and favorably compared to hydrodynamic simulation results.

  18. Instability of a planar expansion wave

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.; Zalesak, S. T.; Metzler, N.; Wouchuk, J. G.

    2005-10-01

    An expansion wave is produced when an incident shock wave interacts with a surface separating a fluid from a vacuum. Such an interaction starts the feedout process that transfers perturbations from the rippled inner (rear) to the outer (front) surface of a target in inertial confinement fusion. Being essentially a standing sonic wave superimposed on a centered expansion wave, a rippled expansion wave in an ideal gas, like a rippled shock wave, typically produces decaying oscillations of all fluid variables. Its behavior, however, is different at large and small values of the adiabatic exponent γ . At γ>3 , the mass modulation amplitude δm in a rippled expansion wave exhibits a power-law growth with time ∝ tβ , where β= (γ-3) / (γ-1) . This is the only example of a hydrodynamic instability whose law of growth, dependent on the equation of state, is expressed in a closed analytical form. The growth is shown to be driven by a physical mechanism similar to that of a classical Richtmyer-Meshkov instability. In the opposite extreme γ-1≪1 , δm exhibits oscillatory growth, approximately linear with time, until it reaches its peak value ˜ (γ-1)-1/2 , and then starts to decrease. The mechanism driving the growth is the same as that of Vishniac’s instability of a blast wave in a gas with low γ . Exact analytical expressions for the growth rates are derived for both cases and favorably compared to hydrodynamic simulation results.

  19. Instability of a planar expansion wave.

    PubMed

    Velikovich, A L; Zalesak, S T; Metzler, N; Wouchuk, J G

    2005-10-01

    An expansion wave is produced when an incident shock wave interacts with a surface separating a fluid from a vacuum. Such an interaction starts the feedout process that transfers perturbations from the rippled inner (rear) to the outer (front) surface of a target in inertial confinement fusion. Being essentially a standing sonic wave superimposed on a centered expansion wave, a rippled expansion wave in an ideal gas, like a rippled shock wave, typically produces decaying oscillations of all fluid variables. Its behavior, however, is different at large and small values of the adiabatic exponent gamma. At gamma > 3, the mass modulation amplitude delta(m) in a rippled expansion wave exhibits a power-law growth with time alpha(t)beta, where beta = (gamma - 3)/(gamma - 1). This is the only example of a hydrodynamic instability whose law of growth, dependent on the equation of state, is expressed in a closed analytical form. The growth is shown to be driven by a physical mechanism similar to that of a classical Richtmyer-Meshkov instability. In the opposite extreme gamma - 1 < 1, delta(m) exhibits oscillatory growth, approximately linear with time, until it reaches its peak value approximately (gamma - 1)(-1/2), and then starts to decrease. The mechanism driving the growth is the same as that of Vishniac's instability of a blast wave in a gas with low . Exact analytical expressions for the growth rates are derived for both cases and favorably compared to hydrodynamic simulation results. PMID:16383532

  20. Classical nuclear motion coupled to electronic non-adiabatic transitions

    SciTech Connect

    Agostini, Federica; Abedi, Ali; Gross, E. K. U.

    2014-12-07

    Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.

  1. Adiabatic effects in the dynamics of Langmuir solitons

    SciTech Connect

    Astrelin, V.T.; Breizman, B.N.; Sedlacek, Z.; Jungwirth, K.

    1988-06-01

    The adiabatic slowness with which the plasma density profile is reconstructed from localized in large-amplitude Langmuir solitons is characteristic of such solitons. Several examples making use of this feature in the description of the soliton dynamics are given. Specifically, long-lived states in the form of composite solitons ar found. Additional limitations are found on the interaction of solitons with each other and with sound waves. The effect of the adiabatic nature on the formation of solitons from free plasmons is discussed.

  2. Adiabatic computation: A toy model

    NASA Astrophysics Data System (ADS)

    Ribeiro, Pedro; Mosseri, Rémy

    2006-10-01

    We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the α parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-α plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.

  3. Adiabatic computation: A toy model

    SciTech Connect

    Ribeiro, Pedro; Mosseri, Remy

    2006-10-15

    We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the {alpha} parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-{alpha} plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.

  4. Adiabatic evolution of plasma equilibrium

    PubMed Central

    Grad, H.; Hu, P. N.; Stevens, D. C.

    1975-01-01

    A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729

  5. Elementary examples of adiabatic invariance

    NASA Astrophysics Data System (ADS)

    Crawford, Frank S.

    1990-04-01

    Simple classical one-dimensional systems subject to adiabatic (gradual) perturbations are examined. The first examples are well known: the adiabatic invariance of the product Eτ of energy E and period τ for the simple pendulum and for the simple harmonic oscillator. Next, the adiabatic invariants of the vertical bouncer are found—a ball bouncing elastically from the floor of a rising elevator having slowly varying velocity and acceleration. These examples lead to consideration of adiabatic invariance for one-dimensional systems with potentials of the form V=axn, with a=a(t) slowly varying in time. Then, the horizontal bouncer is considered—a mass sliding on a smooth floor, bouncing back and forth between two impenetrable walls, one of which is slowly moving. This example is generalized to a particle in a bound state of a general potential with one slowly moving ``turning point.'' Finally, circular motion of a charged particle in a magnetic field slowly varying in time under three different configurations is considered: (a) a free particle in a uniform field; (b) a free particle in a nonuniform ``betatron'' field; and (c) a particle constrained to a circular orbit in a uniform field.

  6. Pressure Oscillations in Adiabatic Compression

    ERIC Educational Resources Information Center

    Stout, Roland

    2011-01-01

    After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…

  7. Transitionless driving on adiabatic search algorithm

    SciTech Connect

    Oh, Sangchul; Kais, Sabre

    2014-12-14

    We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.

  8. Studies in Chaotic adiabatic dynamics

    SciTech Connect

    Jarzynski, C.

    1994-01-01

    Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the {open_quotes}goodness{close_quotes} of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees).

  9. [The characteristics of blast traumatic brain injury].

    PubMed

    Matsumoto, Yoshihisa; Hatano, Ben; Matsushita, Yoshitaro; Nawashiro, Hiroshi; Shima, Katsuji

    2010-08-01

    With the increase in terrorist activity in recent times, the number of blast injuries has also increased in civilian and military settings. In a recent war, the number of patients who suffered blast traumatic brain injury (bTBI) increased, so treatment of bTBI is currently a very important issue. Blast injury is complicated and can be divided into 4 categories: primary, secondary, tertiary, and quaternary. Primary blast injury results from exposure to blast waves; secondary blast injury is trauma caused by fragments of explosive devices; tertiary blast injury is the result of collision with objects; and quaternary blast injury is the result of exposure to toxic and other substances. Blast waves mainly injure air-containing organs such as the lung, bowel, and ear. The brain may also be affected by blast waves. From the clinical perspective, hyperemia and severe cerebral edema occur frequently in patients who sustain significant bTBI. Penetrating or closed head injury caused by the explosion may be associated with vasospasm and pseudoaneurysm formation. Mild traumatic brain injury during war can be associated with posttraumatic stress disorder. To elucidate the mechanism of bTBI, many research works using animal models and computer analysis are underway. Such studies have so far shown that blast waves can cause damage to the brain tissue and cognitive deficits; however, detailed investigations on this topic are still required. Treatment of bTBI patients may require clinical knowledge and skills related to intensive care, neurology, and neurosurgery. Moreover, further research is required in this field. PMID:20697143

  10. Adiabatic far-field sub-diffraction imaging

    PubMed Central

    Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang

    2015-01-01

    The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale. PMID:26258769

  11. Use of a fast near-infrared spectrometer for absorption and emission measurements within the expanding blast wave of a high explosive

    NASA Astrophysics Data System (ADS)

    Koch, Jon D.; Carney, Joel; Lightstone, James; Piecuch, Scott

    2012-03-01

    We demonstrate the use of a fast InGaAs array and spectrometer to measure properties related to near-infrared absorption and emission (750 nm -1500 nm) following a high explosive detonation. Using a broadband light source and a rigid absorption gauge, gas temperatures are measured at a rate of 20 kHz for a period of several milliseconds behind the blast wave from a PETN, PBXN-5, and PBXN-113 detonations. The temperature and concentration of water vapor is determined by fitting experimental transmission spectra to a simulated database. Strong emission signatures obtained during the PETN breakout event (integrated over approximately the first 20 microseconds) indicate the presence of high energy nitrogen and oxygen atoms. Measurements from water absorption at a distance of 23 cm from the PETN charge indicate temperatures decaying from 1600 K to 600 K during the first few milliseconds, and measurements of non-ideal explosives with optically thick postdetonation environments are also demonstrated. These measurements are intended to aid the development of detonation and explosive simulations.

  12. Transition to turbulence and effect of initial conditions on three-dimensional compressible mixing in planar blast-wave-driven systems

    SciTech Connect

    Miles, A.R.; Blue, B.; Edwards, M.J.; Greenough, J.A.; Hansen, J.F.; Robey, H.F.; Drake, R.P.; Kuranz, C.; Leibrandt, D.R.

    2005-05-15

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional (3D) numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pretransition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernovae are discussed.

  13. Effect of Initial Conditions on 2D Rayleigh-Taylor Instability and Transition to Turbulence in Planar Blast-wave-driven Systems

    SciTech Connect

    Miles, A R; Edwards, M J; Greenough, J A

    2004-03-26

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, we present the first results from a computational study of such a system under drive conditions to be attainable on the National Ignition Facility. Using the multiphysics, AMR, higher order Godunov Eulerian hydrocode, Raptor, we consider the late nonlinear instability evolution for multiple amplitude and phase realizations of a variety of multimode spectral types. We show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions by allowing for memory of the initial conditions to be retained in the mix width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. Certain aspects of the initial conditions, including the rms amplitude, are shown to have a strong effect on the time to transition to the quasi-self-similar regime.

  14. Transition to turbulence and effect of initial conditions on three-dimensional compressible mixing in planar blast-wave-driven systemsa)

    NASA Astrophysics Data System (ADS)

    Miles, A. R.; Blue, B.; Edwards, M. J.; Greenough, J. A.; Hansen, J. F.; Robey, H. F.; Drake, R. P.; Kuranz, C.; Leibrandt, D. R.

    2005-05-01

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional (3D) numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pretransition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernovae are discussed.

  15. Effect of initial conditions on two-dimensional Rayleigh-Taylor instability and transition to turbulence in planar blast-wave-driven systems

    NASA Astrophysics Data System (ADS)

    Miles, A. R.; Edwards, M. J.; Greenough, J. A.

    2004-11-01

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, the results from a computational study of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution for multiple amplitude and phase realizations of a variety of multimode spectral types is considered. Compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions by allowing for memory of the initial conditions to be retained in the mix-width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. Certain aspects of the initial conditions, including the rms amplitude, are shown to have a strong effect on the time to transition to the quasi-self-similar regime.

  16. Responsibility of a Filament Eruption for the Initiation of a Flare, CME, and Blast Wave, and its Possible Transformation into a Bow Shock

    NASA Astrophysics Data System (ADS)

    Grechnev, V. V.; Uralov, A. M.; Kuzmenko, I. V.; Kochanov, A. A.; Chertok, I. M.; Kalashnikov, S. S.

    2015-01-01

    Multi-instrument observations of two filament eruptions on 24 February and 11 May 2011 suggest the following updated scenario for eruptive flare, coronal mass ejection (CME), and shock wave evolution. An initial destabilization of a filament results in stretching out of the magnetic threads belonging to its body that are rooted in the photosphere along the inversion line. Their reconnection leads to i) heating of parts of the filament or its environment, ii) an initial development of the flare cusp, arcade, and ribbons, iii) an increasing similarity of the filament to a curved flux rope, and iv) to its acceleration. Then the pre-eruption arcade enveloping the filament becomes involved in reconnection according to the standard model and continues to form the flare arcade and ribbons. The poloidal magnetic flux in the curved rope developing from the filament progressively increases and forces its toroidal expansion. This flux rope impulsively expands and produces a magnetohydrodynamical disturbance, which rapidly steepens into a shock. The shock passes through the arcade that expands above the filament and then freely propagates for some time ahead of the CME like a decelerating blast wave. If the CME is slow, then the shock eventually decays. Otherwise, the frontal part of the shock changes into the bow-shock regime. This was observed for the first time in the 24 February 2011 event. When reconnection ceases, the flux rope relaxes and constitutes the CME core-cavity system. The expanding arcade develops into the CME frontal structure. We also found that reconnection in the current sheet of a remote streamer forced by the shock passage results in a running flare-like process within the streamer responsible for a type II burst. The development of dimming and various associated phenomena are discussed.

  17. Shock wave synthesis of γ-Si3[O,N]4 in the new Freiberg blasting facility under different conditions

    NASA Astrophysics Data System (ADS)

    Renno, A. D.; Schlothauer, T.; Schwarz, M. R.; Heide, G.; Kroke, E.

    2011-12-01

    The new subterranean blasting facility at the TU Bergakademie Freiberg allows experiments at elevated capacities of 20 kg C4-equivalent. The new installation permits the investigation of phase transitions of γ Si3N4 under dynamic loading. We studied the influence of plate thickness (shock duration) and different precursor-pressure powder (Cu, NaCl) mixtures at charge masses between 2000 and 20.000 g C4. Systematic studies showed that the Mach-reflection (so called "upstreaming jetting phenomena") is of vital importance for the synthesis success, due to the fact that the T-p ratio will increase dramatically [Milyavskii et al., 2006]. We synthesized pure γ-Si3[O,N]4 from H-bearing precursors at pressures > 25 GPa [Schlothauer et al., 2011]. The phase transition Si2N2NH into γ-Si3[O,N]4 is completely reconstructive and requires a high temperature-pressure-ratio of 176 K/GPa at pressures up to 35 GPa. Despite the high energy density during the shock wave synthesis process it will be inevitable to prepare the samples under an inert nitrogen atmosphere. References Milyavskii, V. V., V. E. Fortov, A. A. Frolova, K. V. Khishchenko, A. A. Charakhch'yan, and L. V. Shurshalov (2006), Calculation of shock compression of porous media in conical solid-state targets with an outlet hole, Computational Mathematics and Mathematical Physics, 46(5), 873 890. Schlothauer, T., M. R. Schwarz, M. Ovidiu, E. Brendler, R. Moeckel, E. Kroke, and G. Heide (2011), Shock wave synthesis of oxygen-bearing spinel-type silicon nitride (g-Si3(O,N)4 in the pressurerange from 30 to 72 GPa with high purity, in Minerals as Advanced Materials II, edited by S. V. Krivovichev, pp. 389 401, Springer. Berlin Heidelberg.

  18. Coherent tunneling by adiabatic process in a four-waveguide optical coupler

    NASA Astrophysics Data System (ADS)

    Shi, Jian; Ma, Rui-Qiong; Duan, Zuo-Liang; Liang, Meng; Zhang, Wen-wen; Dong, Jun

    2016-07-01

    We numerically simulate Schrödinger-like paraxial wave equation of a four-waveguide system. The coherent tunneling by adiabatic passage in a four-waveguide optical coupler is analyzed by borrowing the dressed state theory of coherent atom system. We discuss the optical coupling mechanism and coupling efficiency of light energy in both intuitive and counterintuitive tunneling schemes and analyze the threshold condition from adiabatic to non-adiabatic regimes in intuitive scheme. The results show that this coupler can be used as power splitter under certain conditions.

  19. Exit of a blast wave from a conical nozzle. [flow field calculations by Eulerian computer code DORF

    NASA Technical Reports Server (NTRS)

    Kim, K.; Johnson, W. E.

    1976-01-01

    The Eulerian computer code DORF was used in the analysis of a two-dimensional, unsteady flow field resulting from semi-confined explosions for propulsive applications. Initially, the ambient gas inside the conical shaped nozzle is set into motion due to the expansion of the explosion product gas, forming a shock wave. When this shock front exits the nozzle, it takes almost a spherical form while a complex interaction between the nozzle and compression and rarefaction waves takes place behind the shock. The results show an excellent agreement with experimental data.

  20. Invalidity of the quantitative adiabatic condition and general conditions for adiabatic approximations

    NASA Astrophysics Data System (ADS)

    Li, Dafa

    2016-05-01

    The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.

  1. Management of primary blast injury.

    PubMed

    Argyros, G J

    1997-07-25

    Blast waves are produced following the detonation of munitions, the firing of large caliber guns, or from any type of explosion. These blast waves can be powerful enough to injure the individuals exposed to them. This type of injury is called primary blast injury (PBI) and the organs most vulnerable to PBI are the gas-filled organs, namely the ear, the lungs and the gastrointestinal tract. The approach to the casualty with PBI is the same as it would be for any trauma victim, i.e. the initiation of life support measures. Attention should be directed to the common life-threatening manifestation of thoracic and abdominal PBI. Pulmonary manifestations would include hemorrhage, barotrauma and arterial air embolism, while abdominal manifestations would include hemorrhage and hollow organ rupture. Therapy is directed at the specific manifestations as well as avoiding additional iatrogenic injury. PMID:9217319

  2. Macro-mechanical modeling of blast-wave mitigation in foams. Part II: reliability of pressure measurements

    NASA Astrophysics Data System (ADS)

    Britan, A.; Liverts, M.; Shapiro, H.; Ben-Dor, G.

    2013-02-01

    A phenomenological study of the process occurring when a plane shock wave reflected off an aqueous foam column filling the test section of a vertical shock tube has been undertaken. The experiments were conducted with initial shock wave Mach numbers in the range 1.25le {M}_s le 1.7 and foam column heights in the range 100-450 mm. Miniature piezotrone circuit electronic pressure transducers were used to record the pressure histories upstream and alongside the foam column. The aim of these experiments was to find a simple way to eliminate a spatial averaging as an artifact of the pressure history recorded by the side-on transducer. For this purpose, we discuss first the common behaviors of the pressure traces in extended time scales. These observations evidently quantify the low frequency variations of the pressure field within the different flow domains of the shock tube. Thereafter, we focus on the fronts of the pressure signals, which, in turn, characterize the high-frequency response of the foam column to the shock wave impact. Since the front shape and the amplitude of the pressure signal most likely play a significant role in the foam destruction, phase changes and/or other physical factors, such as high capacity, viscosity, etc., the common practice of the data processing is revised and discussed in detail. Generally, side-on pressure measurements must be used with great caution when performed in wet aqueous foams, because the low sound speed is especially prone to this effect. Since the spatial averaged recorded pressure signals do not reproduce well the real behaviors of the pressure rise, the recorded shape of the shock wave front in the foam appears much thicker. It is also found that when a thin liquid film wet the sensing membrane, the transducer sensitivity was changed. As a result, the pressure recorded in the foam could exceed the real amplitude of the post-shock wave flow. A simple procedure, which allows correcting this imperfection, is discussed in

  3. Membrane characteristics for biological blast overpressure testing using blast simulators.

    PubMed

    Alphonse, Vanessa D; Siva Sai Sujith Sajja, Venkata; Kemper, Andrew R; Rizel, Dave V; Duma, Stefan M; VandeVord, Pamela J

    2014-01-01

    Blast simulators often use passive-rupture membranes to generate shock waves similar to free-field blasts. The purpose of this study was to compare rupture patterns and pressure traces of three distinct membrane materials for biological and biomechanical blast studies. An Advanced Blast Simulator (ABS) located at the Center for Injury Biomechanics at Virginia Tech was used to test membrane characteristics. Acetate, Mylar, and aluminum sheets with different thicknesses were used to obtain pressures between 70–210 kPa. Static pressure was measured inside the tube at the test section using piezoelectric pressure sensors. Peak overpressure, positive duration, and positive impulse were calculated for each test. Rupture patterns and characteristic pressure traces were unique to each membrane type and thickness. Shock wave speed ranged between 1.2-1.8 Mach for static overpressures of 70–210 kPa. Acetate membranes fragmented sending pieces down the tube, but produced ideal (Friedlander) pressure traces. Mylar membranes bulged without fragmenting, but produced less-than-ideal pressure traces. Aluminum membranes did not fragment and produced ideal pressure traces. However, the cost of manufacturing and characterizing aluminum membranes should be considered during membrane selection. This study illustrates the advantages and disadvantages of using Mylar, acetate, and aluminum for passive rupture membranes for blast simulators. PMID:25405432

  4. Adiabatic Wankel type rotary engine

    NASA Technical Reports Server (NTRS)

    Kamo, R.; Badgley, P.; Doup, D.

    1988-01-01

    This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.

  5. Adiabatic processes in monatomic gases

    NASA Astrophysics Data System (ADS)

    Carrera-Patiño, Martin E.

    1988-08-01

    A kinetic model is used to predict the temperature evolution of a monatomic ideal gas undergoing an adiabatic expansion or compression at a constant finite rate, and it is then generalized to treat real gases. The effects of interatomic forces are considered, using as examples the gas with the square-well potential and the van der Waals gas. The model is integrated into a Carnot cycle operating at a finite rate to compare the efficiency's rate-dependent behavior with the reversible result. Limitations of the model, rate penalties, and their importance are discussed.

  6. Adiabatic preparation of Floquet condensates

    NASA Astrophysics Data System (ADS)

    Heinisch, Christoph; Holthaus, Martin

    2016-10-01

    We argue that a Bose-Einstein condensate can be transformed into a Floquet condensate, that is, into a periodically time-dependent many-particle state possessing the coherence properties of a mesoscopically occupied single-particle Floquet state. Our reasoning is based on the observation that the denseness of the many-body system's quasienergy spectrum does not necessarily obstruct effectively adiabatic transport. Employing the idealized model of a driven bosonic Josephson junction, we demonstrate that only a small amount of Floquet entropy is generated when a driving force with judiciously chosen frequency and maximum amplitude is turned on smoothly.

  7. Differential geometric treewidth estimation in adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Wang, Chi; Jonckheere, Edmond; Brun, Todd

    2016-07-01

    The D-Wave adiabatic quantum computing platform is designed to solve a particular class of problems—the Quadratic Unconstrained Binary Optimization (QUBO) problems. Due to the particular "Chimera" physical architecture of the D-Wave chip, the logical problem graph at hand needs an extra process called minor embedding in order to be solvable on the D-Wave architecture. The latter problem is itself NP-hard. In this paper, we propose a novel polynomial-time approximation to the closely related treewidth based on the differential geometric concept of Ollivier-Ricci curvature. The latter runs in polynomial time and thus could significantly reduce the overall complexity of determining whether a QUBO problem is minor embeddable, and thus solvable on the D-Wave architecture.

  8. Differential geometric treewidth estimation in adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Wang, Chi; Jonckheere, Edmond; Brun, Todd

    2016-10-01

    The D-Wave adiabatic quantum computing platform is designed to solve a particular class of problems—the Quadratic Unconstrained Binary Optimization (QUBO) problems. Due to the particular "Chimera" physical architecture of the D-Wave chip, the logical problem graph at hand needs an extra process called minor embedding in order to be solvable on the D-Wave architecture. The latter problem is itself NP-hard. In this paper, we propose a novel polynomial-time approximation to the closely related treewidth based on the differential geometric concept of Ollivier-Ricci curvature. The latter runs in polynomial time and thus could significantly reduce the overall complexity of determining whether a QUBO problem is minor embeddable, and thus solvable on the D-Wave architecture.

  9. Modelling of blast loading on aboveground structures - I. General phenomenology and external blast

    NASA Astrophysics Data System (ADS)

    Beshara, F. B. A.

    1994-06-01

    The paper is concerned with the prediction of dynamic effects of unconfined explosions needed for the structural analysis of blast-loaded aboveground structures. The basic features of the explosion and blast wave phenomena are presented along with a discussion of TNT equivalency and blast scaling laws. The characteristics of incident overpressure loading due to atomic weapons, conventional high explosives and unconfined vapour cloud explosions are addressed and followed by a description of the other blast loading components associated with air flow and reflection process. In the final part, the modelling of external blast loads on the different faces of aboveground rigid structures is considered. A unified approach is followed in the presentation of the governing equations of modelling of blast loads for mathematical and practical applications.

  10. On the question of adiabatic invariants

    NASA Astrophysics Data System (ADS)

    Mitropol'Skii, Iu. A.

    Some aspects of the construction of adiabadic invariants for dynamic systems with a single degree of freedom are discussed. Adiabatic invariants are derived using classical principles and the method proposed by Djukic (1981). The discussion covers an adiabatic invariant for a dynamic system with slowly varying parameters; derivation of an expression for an adiabatic invariant by the Djukic method for a second-order equation with a variable mass; and derivation of an expression for the adiabatic invariant for a nearly integrable differential equation.

  11. Conversion of piston-driven shocks from powerful solar flares to blast waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Pinter, S.; Dryer, M.

    1990-01-01

    Published observational data on 39 combined type-II/type-IV solar radio bursts from the period 1972-1982 are analyzed, with a focus on the potential use of the type-IV burst duration to predict the time of arrival at earth of piston-driven shock waves (extending and modifying the prediction method proposed by Smart and Shea, 1985). The data and analysis results are presented in tables and graphs and characterized in detail. It is found that a typical shock of this type leaves the solar flare at velocity 1560 km/sec and continues for a distance of 0.12 AU, decelerates as it is convected by the solar wind, and has a travel time of about 48.5 h. The mean deviation between predicted and measured arrival times is 1.40 h, with standard deviation 1.25 h.

  12. Silencing by blasting: combination of laser pulse induced stress waves and magnetophoresis for siRNA delivery

    NASA Astrophysics Data System (ADS)

    Babincová, M.; Babincová, N.; Durdík, S.; Bergemann, C.; Sourivong, P.

    2016-06-01

    A new method is developed for efficient delivery of short interference RNA into cells using combination of magnetophoresis for pre-concentration of siRNA-magnetic nanoparticle complex on the surface of cells with subsequent nanosecond laser pulse generating stress waves in transfection chamber, which is able to permeabilize cell membrane for the facilitated delivery of siRNA into the cell interior. As has been shown using siRNA inducing cell apoptosis, combination of these two physical factors increased the efficiency of three different human carcinoma cells transfection to 93%, 89%, and 84%, for HeLa (cervical carcinoma), MCF-7 (breast carcinoma), and UCI-107 (ovarian carcinoma) cells, respectively. This new physical method of siRNA delivery may have therefore far reaching applications in biotechnology and functional genomics.

  13. Protecting and accelerating adiabatic passage with time-delayed pulse sequences.

    PubMed

    Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R

    2016-05-21

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness. PMID:27125342

  14. Protecting and accelerating adiabatic passage with time-delayed pulse sequences.

    PubMed

    Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R

    2016-05-21

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness.

  15. Note: A table-top blast driven shock tube.

    PubMed

    Courtney, Michael W; Courtney, Amy C

    2010-12-01

    The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

  16. Note: A table-top blast driven shock tube

    NASA Astrophysics Data System (ADS)

    Courtney, Michael W.; Courtney, Amy C.

    2010-12-01

    The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

  17. Note: A table-top blast driven shock tube.

    PubMed

    Courtney, Michael W; Courtney, Amy C

    2010-12-01

    The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test. PMID:21198058

  18. Computational modeling of human head under blast in confined and open spaces: primary blast injury.

    PubMed

    Rezaei, A; Salimi Jazi, M; Karami, G

    2014-01-01

    In this paper, a computational modeling for biomechanical analysis of primary blast injuries is presented. The responses of the brain in terms of mechanical parameters under different blast spaces including open, semi-confined, and confined environments are studied. In the study, the effect of direct and indirect blast waves from the neighboring walls in the confined environments will be taken into consideration. A 50th percentile finite element head model is exposed to blast waves of different intensities. In the open space, the head experiences a sudden intracranial pressure (ICP) change, which vanishes in a matter of a few milliseconds. The situation is similar in semi-confined space, but in the confined space, the reflections from the walls will create a number of subsequent peaks in ICP with a longer duration. The analysis procedure is based on a simultaneous interaction simulation of the deformable head and its components with the blast wave propagations. It is concluded that compared with the open and semi-confined space settings, the walls in the confined space scenario enhance the risk of primary blast injuries considerably because of indirect blast waves transferring a larger amount of damaging energy to the head. PMID:23996897

  19. Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.

    PubMed

    Goldstein, Lee E; Fisher, Andrew M; Tagge, Chad A; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A; Upreti, Chirag; Kracht, Jonathan M; Ericsson, Maria; Wojnarowicz, Mark W; Goletiani, Cezar J; Maglakelidze, Giorgi M; Casey, Noel; Moncaster, Juliet A; Minaeva, Olga; Moir, Robert D; Nowinski, Christopher J; Stern, Robert A; Cantu, Robert C; Geiling, James; Blusztajn, Jan K; Wolozin, Benjamin L; Ikezu, Tsuneya; Stein, Thor D; Budson, Andrew E; Kowall, Neil W; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F; Moss, William C; Cleveland, Robin O; Tanzi, Rudolph E; Stanton, Patric K; McKee, Ann C

    2012-05-16

    Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein-linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory.

  20. Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.

    PubMed

    Goldstein, Lee E; Fisher, Andrew M; Tagge, Chad A; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A; Upreti, Chirag; Kracht, Jonathan M; Ericsson, Maria; Wojnarowicz, Mark W; Goletiani, Cezar J; Maglakelidze, Giorgi M; Casey, Noel; Moncaster, Juliet A; Minaeva, Olga; Moir, Robert D; Nowinski, Christopher J; Stern, Robert A; Cantu, Robert C; Geiling, James; Blusztajn, Jan K; Wolozin, Benjamin L; Ikezu, Tsuneya; Stein, Thor D; Budson, Andrew E; Kowall, Neil W; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F; Moss, William C; Cleveland, Robin O; Tanzi, Rudolph E; Stanton, Patric K; McKee, Ann C

    2012-05-16

    Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein-linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory. PMID:22593173

  1. Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model

    PubMed Central

    Goldstein, Lee E.; Fisher, Andrew M.; Tagge, Chad A.; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A.; Upreti, Chirag; Kracht, Jonathan M.; Ericsson, Maria; Wojnarowicz, Mark W.; Goletiani, Cezar J.; Maglakelidze, Giorgi M.; Casey, Noel; Moncaster, Juliet A.; Minaeva, Olga; Moir, Robert D.; Nowinski, Christopher J.; Stern, Robert A.; Cantu, Robert C.; Geiling, James; Blusztajn, Jan K.; Wolozin, Benjamin L.; Ikezu, Tsuneya; Stein, Thor D.; Budson, Andrew E.; Kowall, Neil W.; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F.; Moss, William C.; Cleveland, Robin O.; Tanzi, Rudolph E.; Stanton, Patric K.; McKee, Ann C.

    2013-01-01

    Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory. PMID:22593173

  2. Nineteen-Foot Diameter Explosively Driven Blast Simulator

    SciTech Connect

    VIGIL,MANUEL G.

    2001-07-01

    This report describes the 19-foot diameter blast tunnel at Sandia National Laboratories. The blast tunnel configuration consists of a 6 foot diameter by 200 foot long shock tube, a 6 foot diameter to 19 foot diameter conical expansion section that is 40 feet long, and a 19 foot diameter test section that is 65 feet long. Therefore, the total blast tunnel length is 305 feet. The development of this 19-foot diameter blast tunnel is presented. The small scale research test results using 4 inch by 8 inch diameter and 2 foot by 6 foot diameter shock tube facilities are included. Analytically predicted parameters are compared to experimentally measured blast tunnel parameters in this report. The blast tunnel parameters include distance, time, static, overpressure, stagnation pressure, dynamic pressure, reflected pressure, shock Mach number, flow Mach number, shock velocity, flow velocity, impulse, flow duration, etc. Shadowgraphs of the shock wave are included for the three different size blast tunnels.

  3. On a Nonlinear Model in Adiabatic Evolutions

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Lu, Song-Feng

    2016-08-01

    In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using. Supported by the National Natural Science Foundation of China under Grant Nos. 61402188 and 61173050. The first author also gratefully acknowledges the support from the China Postdoctoral Science Foundation under Grant No. 2014M552041

  4. Instability of a planar expansion wave

    SciTech Connect

    Velikovich, A.L.; Zalesak, S.T.; Metzler, N.; Wouchuk, J.G.

    2005-10-01

    An expansion wave is produced when an incident shock wave interacts with a surface separating a fluid from a vacuum. Such an interaction starts the feedout process that transfers perturbations from the rippled inner (rear) to the outer (front) surface of a target in inertial confinement fusion. Being essentially a standing sonic wave superimposed on a centered expansion wave, a rippled expansion wave in an ideal gas, like a rippled shock wave, typically produces decaying oscillations of all fluid variables. Its behavior, however, is different at large and small values of the adiabatic exponent {gamma}. At {gamma}>3, the mass modulation amplitude {delta}m in a rippled expansion wave exhibits a power-law growth with time {proportional_to}t{sup {beta}}, where {beta}=({gamma}-3)/({gamma}-1). This is the only example of a hydrodynamic instability whose law of growth, dependent on the equation of state, is expressed in a closed analytical form. The growth is shown to be driven by a physical mechanism similar to that of a classical Richtmyer-Meshkov instability. In the opposite extreme {gamma}-1<<1, {delta}m exhibits oscillatory growth, approximately linear with time, until it reaches its peak value {approx}({gamma}-1){sup -1/2}, and then starts to decrease. The mechanism driving the growth is the same as that of Vishniac's instability of a blast wave in a gas with low {gamma}. Exact analytical expressions for the growth rates are derived for both cases and favorably compared to hydrodynamic simulation results.

  5. Experimental study of blast mitigating devices based on combined construction

    NASA Astrophysics Data System (ADS)

    Takayama, K.; Silnikov, M. V.; Chernyshov, M. V.

    2016-09-01

    A robust blast inhibiting bin is the most often used device for damage blast effects suppression. In particular, a top open cylindrical bin significantly reduces a fragmentation effect resulted from a detonation of an explosive device placed inside the bin. However, reduction of blast wave overpressure and impulse by such cylindrical bins is not sufficient [1]. A reasonable alternative to endless increase of height and thickness of robust blast inhibiting bins is a development of destructible inhibitors having no solid elements in their structure and, therefore, excluding secondary fragmentation. So, the family of "Fountain" inhibitors [2,3] localizes and suppresses damaging blast effects due to multiphase working system. The present study is analyzing data obtained in testing of prototypes of new combined inhibitors. Their structure combines robust elements (bottoms, side surfaces) with elements responsible for blast loads reduction due to multi-phase working system (top and low transverse embeddings) and fairings impeding wave propagation in undesirable directions.

  6. Transport of ultracold atoms between concentric traps via spatial adiabatic passage

    NASA Astrophysics Data System (ADS)

    Polo, J.; Benseny, A.; Busch, Th; Ahufinger, V.; Mompart, J.

    2016-01-01

    Spatial adiabatic passage processes for ultracold atoms trapped in tunnel-coupled cylindrically symmetric concentric potentials are investigated. Specifically, we discuss the matter-wave analog of the rapid adiabatic passage (RAP) technique for a high fidelity and robust loading of a single atom into a harmonic ring potential from a harmonic trap, and for its transport between two concentric rings. We also consider a system of three concentric rings and investigate the transport of a single atom between the innermost and the outermost rings making use of the matter-wave analog of the stimulated Raman adiabatic passage (STIRAP) technique. We describe the RAP-like and STIRAP-like dynamics by means of a two- and a three-state model, respectively, obtaining good agreement with the numerical simulations of the corresponding two-dimensional Schrödinger equation.

  7. Gravitational radiation reaction and inspiral waveforms in the adiabatic limit.

    PubMed

    Hughes, Scott A; Drasco, Steve; Flanagan, Eanna E; Franklin, Joel

    2005-06-10

    We describe progress evolving an important limit of binaries in general relativity: stellar mass compact objects spiraling into much larger black holes. Such systems are of great observational interest. We have developed tools to compute for the first time the radiation from generic orbits. Using global conservation laws, we find the orbital evolution and waveforms for special cases. For generic orbits, inspirals and waveforms can be found by augmenting our approach with an adiabatic self-force rule due to Mino. Such waveforms should be accurate enough for gravitational-wave searches. PMID:16090377

  8. A geometric criterion for adiabatic chaos

    SciTech Connect

    Kaper, T.J. ); Kovacic, G. )

    1994-03-01

    Chaos in adiabatic Hamiltonian systems is a recent discovery and a pervasive phenomenon in physics. In this work, a geometric criterion is discussed based on the theory of action from classical mechanics to detect the existence of Smale horseshoe chaos in adiabatic systems. It is used to show that generic adiabatic planar Hamiltonian systems exhibit stochastic dynamics in large regions of phase space. To illustrate the method, results are obtained for three problems concerning relativistic particle dynamics, fluid mechanics, and passage through resonance, results which either could not be obtained with existing methods, or which were difficult and analytically impractical to obtain with them.

  9. Heating and cooling in adiabatic mixing process

    SciTech Connect

    Zhou Jing; Zou Xubo; Guo Guangcan; Cai Zi

    2010-12-15

    We study the effect of interaction on the temperature change in the process of adiabatic mixing of two components of Fermi gases using the real-space Bogoliubov-de Gennes method. We find that in the process of adiabatic mixing, the competition between the adiabatic expansion and the attractive interaction makes it possible to cool or heat the system depending on the strength of the interaction and the initial temperature of the system. The changes of the temperature in a bulk system and in a trapped system are investigated.

  10. Blast Loading Experiments of Surrogate Models for Tbi Scenarios

    NASA Astrophysics Data System (ADS)

    Alley, M. D.; Son, S. F.

    2009-12-01

    This study aims to characterize the interaction of explosive blast waves through simulated anatomical models. We have developed physical models and a systematic approach for testing traumatic brain injury (TBI) mechanisms and occurrences. A simplified series of models consisting of spherical PMMA shells housing synthetic gelatins as brain simulants have been utilized. A series of experiments was conducted to compare the sensitivity of the system response to mechanical properties of the simulants under high strain-rate explosive blasts. Small explosive charges were directed at the models to produce a realistic blast wave in a scaled laboratory test cell setting. Blast profiles were measured and analyzed to compare system response severity. High-speed shadowgraph imaging captured blast wave interaction with the head model while particle tracking captured internal response for displacement and strain correlation. The results suggest amplification of shock waves inside the head near material interfaces due to impedance mismatches. In addition, significant relative displacement was observed between the interacting materials suggesting large strain values of nearly 5%. Further quantitative results were obtained through shadowgraph imaging of the blasts confirming a separation of time scales between blast interaction and bulk movement. These results lead to the conclusion that primary blast effects could cause TBI occurrences.

  11. Experimental modeling of explosive blast-related traumatic brain injuries.

    PubMed

    Alley, Matthew D; Schimizze, Benjamin R; Son, Steven F

    2011-01-01

    This study aims to characterize the interaction of explosive blast waves through simulated anatomical systems. We have developed physical models and a systematic approach for testing traumatic brain injury (TBI) mechanisms and occurrences. A simplified series of models consisting of spherical poly(methyl methacrylate) (PMMA) shells housing synthetic gelatins as brain simulants have been utilized. A series of experiments was conducted to compare the sensitivity of the system response to mechanical properties of the simulants under high strain-rate explosive blasts. Small explosive charges were directed at the models to produce a realistic blast wave in a scaled laboratory setting. Blast profiles were measured and analyzed to compare system response severity. High-speed shadowgraph imaging captured blast wave interaction with the head model while particle tracking captured internal response for displacement and strain correlation. The results suggest amplification of shock waves inside the head near material interfaces due to impedance mismatches. In addition, significant relative displacement was observed between the interacting materials suggesting large strain values of nearly 5%. Further quantitative results were obtained through shadowgraph imaging of the blasts confirming a separation of time scales between blast interaction and bulk movement. These results lead to a conclusion that primary blast effects may potentially contribute significantly to the occurrence of military associated TBI. PMID:20580931

  12. Adiabatic principles in atom-diatom collisional energy transfer

    SciTech Connect

    Hovingh, W.J.

    1993-01-01

    This work describes the application of numerical methods to the solution of the time dependent Schroedinger equation for non-reactive atom-diatom collisions in which only one of the degrees of freedom has been removed. The basic method involves expanding the wave function in a basis set in two of the diatomic coordinates in a body-fixed frame (with respect to the triatomic complex) and defining the coefficients in that expansion as functions on a grid in the collision coordinate. The wave function is then propagated in time using a split operator method. The bulk of this work is devoted to the application of this formalism to the study of internal rotational predissociation in NeHF, in which quasibound states of the triatom predissociate through the transfer of energy from rotation of the diatom into translational energy in the atom-diatom separation coordinate. The author analyzes the computed time dependent wave functions to calculate the lifetimes for several quasibound states; these are in agreement with time independent quantum calculations using the same potential. Moreover, the time dependent behavior of the wave functions themselves sheds light on the dynamics of the predissociation processes. Finally, the partial cross sections of the products in those processes is determined with multiple exit channels. These show strong selectivity in the orbital angular momentum of the outgoing fragments, which the author explains with an adiabatic channel interpretation of the wave function's dynamics. The author also suggests that the same formalism might profitably be used to investigate the quantum dynamics of [open quotes]quasiresonant vibration-rotation transfer[close quotes], in which remarkably strong propensity rules in certain inelastic atom-diatom collision arise from classical adiabatic invariance theory.

  13. The influence of personal blast protection on the distribution and severity of primary blast gut injury.

    PubMed

    Cripps, N P; Cooper, G J

    1996-03-01

    Primary blast injuries have been recognized since World War I when the most significant reported injury was to the lung. The prevalence of injury to tissues containing air was underlined by the frequency of gut blast injury in underwater explosions mostly reported during World War II. Gut injury is the most likely cause of mortality after the more immediate effects of pulmonary primary blast injury. Effective protection has been achieved for lungs exposed to short duration external blast waves by the placement of stress wave decouplers on to the thoracoabdominal wall in a pig model, thus modifying the energy coupled into the body. A combination of two densities of glass-reinforced plastic plate and Plastazote foam (GRP/PZ) effectively eliminated pulmonary injury in 17 protected animals, compared with the production of severe blast lung in nine unprotected animals (p < 0.001). Partial pulmonary protection was achieved using a plasticized lead and plastazote foam decoupling combination (PbPVC/PZ) in a further group of 10 animals. Peak incident overpressures were not significantly different in any group. Small bowel contusions were highly significantly reduced in the GRP/PZ groups when compared with unprotected animals and with PbPVC protected animals (both p < 0.001); no significant reduction was observed in the summed colonic contusion size in any protected group. Intestinal perforations were also highly significantly reduced in both GRP/PZ groups (p < 0.001). Primary pulmonary blast injury and probably small bowel injury are caused by the propagation of coupled stress waves within the body. Elimination of these injuries implies prevention of stress wave propagation. Because colonic injury was not prevented by the same protection, a different mechanism for the injury is suggested: transmission and propagation of shear waves. These findings have important implications for blast protection and the clinical management of primary blast casualties. PMID:8606411

  14. Blast traumatic brain injury in the rat using a blast overpressure model.

    PubMed

    Yarnell, Angela M; Shaughness, Michael C; Barry, Erin S; Ahlers, Stephen T; McCarron, Richard M; Grunberg, Neil E

    2013-01-01

    Traumatic brain injury (TBI) is a serious health concern for civilians and military populations, and blast-induced TBI (bTBI) has become an increasing problem for military personnel over the past 10 years. To understand the biological and psychological effects of blast-induced injuries and to examine potential interventions that may help to prevent, attenuate, and treat effects of bTBI, it is valuable to conduct controlled animal experiments. This unit discusses available paradigms to model traumatic brain injury in animals, with an emphasis on the relevance of these various models to study blast-induced traumatic brain injury (bTBI). This paper describes the detailed methods of a blast overpressure (BOP) paradigm that has been used to conduct experiments with rats to model blast exposure. This particular paradigm models the pressure wave created by explosions, including improvised explosive devices (IEDs).

  15. Simulation of periodically focused, adiabatic thermal beams

    SciTech Connect

    Chen, C.; Akylas, T. R.; Barton, T. J.; Field, D. M.; Lang, K. M.; Mok, R. V.

    2012-12-21

    Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.

  16. Adiabatic Motion of Fault Tolerant Qubits

    NASA Astrophysics Data System (ADS)

    Drummond, David Edward

    This work proposes and analyzes the adiabatic motion of fault tolerant qubits in two systems as candidates for the building blocks of a quantum computer. The first proposal examines a pair of electron spins in double quantum dots, finding that the leading source of decoherence, hyperfine dephasing, can be suppressed by adiabatic rotation of the dots in real space. The additional spin-orbit effects introduced by this motion are analyzed, simulated, and found to result in an infidelity below the error-correction threshold. The second proposal examines topological qubits formed by Majorana zero modes theorized to exist at the ends of semiconductor nanowires coupled to conventional superconductors. A model is developed to design adiabatic movements of the Majorana bound states to produce entangled qubits. Analysis and simulations indicate that these adiabatic operations can also be used to demonstrate entanglement experimentally by testing Bell's theorem.

  17. General conditions for quantum adiabatic evolution

    SciTech Connect

    Comparat, Daniel

    2009-07-15

    Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)

  18. Adiabatic Quantum Search in Open Systems

    NASA Astrophysics Data System (ADS)

    Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.

    2016-10-01

    Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.

  19. Experimental demonstration of composite adiabatic passage

    NASA Astrophysics Data System (ADS)

    Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.

    2013-12-01

    We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.

  20. Adiabatic limits on Riemannian Heisenberg manifolds

    SciTech Connect

    Yakovlev, A A

    2008-02-28

    An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.

  1. Adiabatic invariance of oscillons/I -balls

    NASA Astrophysics Data System (ADS)

    Kawasaki, Masahiro; Takahashi, Fuminobu; Takeda, Naoyuki

    2015-11-01

    Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I -balls. We prove the adiabatic invariance of the oscillons/I -balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such a potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/I -balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/I -balls are only quasistable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the I -balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/I -balls is due to the adiabatic invariance.

  2. Analytical Nonlinear Adiabatic Theory of the Autophase Microwave Tube

    NASA Astrophysics Data System (ADS)

    Belyavskiy, Eugene; Khotiaintsev, Sergei

    We present an analytical nonlinear adiabatic theory of the microwave electron device that we call the Autophase Microwave Tube (AMT). In contrast to the well-known Traveling Wave Tube (TWT), the AMT exploits a highly efficient non-synchronous beam-wave interaction for the amplification (or generation) of the HF electromagnetic waves, and, differently from klystron and such hybrid devices as twystron, it employs a continuous beam-wave interaction. Because of these distinctive features, the AMT presents a special class of microwave electron devices, which feature very high electronic efficiency (which tends to 100%) and large bandwidth. Here, we develop the theory that allows one to find the profiles of static longitudinal electric or magnetic field (or both) over the device length, which yield negligible de-bunching together with highly efficient amplification (generation) of the HF electromagnetic wave. The analysis of electron motion in the bunch is performed by means of Lyapunov stability theory. The numerical example illustrates the possibility of achieving the electronic efficiency of AMT as high as 92%. We compare different autophase regimes in the AMT and show that the profiling of the longitudinal static magnetic focusing field in the helix AMT with the non-azimuthally symmetric wave has many advantages with respect to other regimes.

  3. Adiabatic Demagnetization Cooler For Far Infrared Detector

    NASA Astrophysics Data System (ADS)

    Sato, Akio; Yazawa, Takashi; Yamamoto, Junya

    1988-11-01

    An small adiabatic demagnetization cooler for an astronomical far infrared detector has been built. Single crystals of manganese ammonium sulphate and chromium potassium alum, were prepared as magnetic substances. The superconducting magnet was indirectly cooled and operated by small current up to 13.3 A, the maximum field being 3.5 T. As a preliminary step, adiabatic demagnetization to zero field was implemented. The lowest temperature obtained was 0.5 K, for 5.0 K initial temperature.

  4. Modelling human eye under blast loading.

    PubMed

    Esposito, L; Clemente, C; Bonora, N; Rossi, T

    2015-01-01

    Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues.

  5. Modelling human eye under blast loading.

    PubMed

    Esposito, L; Clemente, C; Bonora, N; Rossi, T

    2015-01-01

    Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues. PMID:23521031

  6. Symmetry of the Adiabatic Condition in the Piston Problem

    ERIC Educational Resources Information Center

    Anacleto, Joaquim; Ferreira, J. M.

    2011-01-01

    This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…

  7. Hierarchical theory of quantum adiabatic evolution

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Gong, Jiangbin; Wu, Biao

    2014-12-01

    Quantum adiabatic evolution is a dynamical evolution of a quantum system under slow external driving. According to the quantum adiabatic theorem, no transitions occur between nondegenerate instantaneous energy eigenstates in such a dynamical evolution. However, this is true only when the driving rate is infinitesimally small. For a small nonzero driving rate, there are generally small transition probabilities between the energy eigenstates. We develop a classical mechanics framework to address the small deviations from the quantum adiabatic theorem order by order. A hierarchy of Hamiltonians is constructed iteratively with the zeroth-order Hamiltonian being determined by the original system Hamiltonian. The kth-order deviations are governed by a kth-order Hamiltonian, which depends on the time derivatives of the adiabatic parameters up to the kth-order. Two simple examples, the Landau-Zener model and a spin-1/2 particle in a rotating magnetic field, are used to illustrate our hierarchical theory. Our analysis also exposes a deep, previously unknown connection between classical adiabatic theory and quantum adiabatic theory.

  8. Laboratory Measurements of Adiabatic and Isothermal Processes

    NASA Astrophysics Data System (ADS)

    McNairy, W. W.

    1997-04-01

    Adiabatic and isothermal measurements on various of gases are made possible by using the Adiabatic Gas Law apparatus made by PASCO Scientific(Much of this work was published by the author in "The Physics Teacher", vol. 34, March 1996, p. 178-80.). By using a computer interface, undergraduates are able to data for monatomic, diatomic and polyatomic gases for both compression and expansion processes. Designed principally to obtain adiabatic data, the apparatus may be easily modified for use in isothermal processes. The various sets of data are imported into a spreadsheet program where fits may be made to the ideal gas law and the adiabatic gas law. Excellent results are obtained for the natural logarithm of pressure versus the natural logarithm of volume for both the isothermal data (expected slope equal to -1 in all cases) and the adiabatic data (slope equal to -1 times the ratio of specific heats for the particular gas). An overview of the lab procedure used at VMI will be presented along with data obtained for several adiabatic and isothermal processes.

  9. Multiphoton Raman Atom Optics with Frequency-Swept Adiabatic Passage

    NASA Astrophysics Data System (ADS)

    Kotru, Krish; Butts, David; Kinast, Joseph; Stoner, Richard

    2016-05-01

    Light-pulse atom interferometry is a promising candidate for future inertial navigators, gravitational wave detectors, and measurements of fundamental physical constants. The sensitivity of this technique, however, is often limited by the small momentum separations created between interfering atom wave packets (typically ~ 2 ℏk) . We address this issue using light-pulse atom optics derived from stimulated Raman transitions and frequency-swept adiabatic rapid passage (ARP). In experiments, these Raman ARP atom optics have generated up to 30 ℏk photon recoil momenta in an acceleration-sensitive atom interferometer, thereby enhancing the phase shift per unit acceleration by a factor of 15. Since this approach forgoes evaporative cooling and velocity selection, it could enable large-area atom interferometry at higher data rates, while also lowering the atom shot-noise-limited measurement uncertainty.

  10. Cosmological shells and blast waves

    NASA Technical Reports Server (NTRS)

    Ostriker, Jeremiah P.

    1986-01-01

    It is argued that cosmic explosions could have produced significant amounts of large-scale structure in the cosmic microwave background (CMB). Observations appear to indicate the presence of bubblelike structures with radii suggesting that positive energy perturbations were more prevalent than negative energy perturbations, since the latter would produce a prevalence of clusterlke irregularities. Energy input from processes occurring during galaxy formation and releasing about 10 to the 61st-62nd ergs per event would not overly disturb the CMB. The merging of bubbles typically resulting in bubbles with radii of roughly (10-20)/h x Mpc also would not affect the CMB. If much larger bubbles of radii 50-100 Mpc exist, a different energy input is likely to be the cause.

  11. Blast wave from buried charges

    SciTech Connect

    Reichenbach, H.; Behrens, K.; Kuhl, A.L.

    1993-08-01

    While much airblast data are available for height-of-burst (HOB) effects, systematic airblast data for depth-of-burst (DOB) effects are more limited. It is logical to ask whether the spherical 0.5-g Nitropenta charges that, proved to be successful for HOB tests at EMI are also suitable for experiments with buried charges in the laboratory scale; preliminary studies indicated in the alternative. Of special interest is the airblast environment generated by detonations just above or below the around surface. This paper presents a brief summary of the test results.

  12. The pathobiology of blast injuries and blast-induced neurotrauma as identified using a new experimental model of injury in mice.

    PubMed

    Cernak, Ibolja; Merkle, Andrew C; Koliatsos, Vassilis E; Bilik, Justin M; Luong, Quang T; Mahota, Theresa M; Xu, Leyan; Slack, Nicole; Windle, David; Ahmed, Farid A

    2011-02-01

    Current experimental models of blast injuries used to study blast-induced neurotrauma (BINT) vary widely, which makes the comparison of the experimental results extremely challenging. Most of the blast injury models replicate the ideal Friedländer type of blast wave, without the capability to generate blast signatures with multiple shock fronts and refraction waves as seen in real-life conditions; this significantly reduces their clinical and military relevance. Here, we describe the pathophysiological consequences of graded blast injuries and BINT generated by a newly developed, highly controlled, and reproducible model using a modular, multi-chamber shock tube capable of tailoring pressure wave signatures and reproducing complex shock wave signatures seen in theater. While functional deficits due to blast exposure represent the principal health problem for today's warfighters, the majority of available blast models induces tissue destruction rather than mimic functional deficits. Thus, the main goal of our model is to reliably reproduce long-term neurological impairments caused by blast. Physiological parameters, functional (motor, cognitive, and behavioral) outcomes, and underlying molecular mechanisms involved in inflammation measured in the brain over the 30 day post-blast period showed this model is capable of reproducing major neurological changes of clinical BINT. PMID:21074615

  13. Pfaffian statistics through adiabatic transport in the 1D coherent state representation.

    PubMed

    Seidel, Alexander

    2008-11-01

    Recent work has shown that the low energy sector of certain quantum Hall states is adiabatically connected to simple charge-density-wave patterns that appear, e.g., when the system is deformed into a thin torus. Here it is shown that the patterns emerging in this limit already determine the non-Abelian statistics of the nu=1 Moore-Read state. Aside from the knowledge of these patterns, the method only relies on the principle of adiabatic continuity, the effectively noncommutative geometry in a strong magnetic field, and topological as well as locality arguments.

  14. Waveform analysis in mitigation of blast-induced vibrations

    NASA Astrophysics Data System (ADS)

    Aldas, G. G. U.; Ecevitoglu, B.

    2008-10-01

    To mitigate the blast-induced ground vibrations, we proposed a new methodology quite different from conventional methods which do not take into account the mechanics of seismic waves. Contrary to conventional methods, the proposed methodology does not consider any blast-parameters such as explosive types and amounts, blast-geometry, blast-hole design, hole-depth/diameter, etc., except time-delays. The methodology aims to employ the most suitable time-delays among blast-hole groupings to minimize destructive interference of the surface waves at the location of blast-induced vibrations. The crucial point of the proposed methodology is the use of a pilot-blast signal which takes account of the seismic properties of all complex geology between the blast and the target locations. Therefore, it does not require any geological model or assumption. The methodology has been implemented at a Turkish Coal Company's Lignite Mine. Blasting induced ground vibrations at this mine could be minimized to a ratio of 1/8.

  15. 30 CFR 56.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... notify the appropriate MSHA district office. (e) In electric blasting prior to connecting to the power... (shock wave), flying material, and gases. (f) Before firing a blast— (1) Ample warning shall be given...

  16. 30 CFR 56.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... notify the appropriate MSHA district office. (e) In electric blasting prior to connecting to the power... (shock wave), flying material, and gases. (f) Before firing a blast— (1) Ample warning shall be given...

  17. 30 CFR 57.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... connecting to the power source, and in nonelectric blasting prior to attaching an initiating device, all... them from concussion (shock wave), flying material, and gases. (f) Before firing a blast— (1)...

  18. 30 CFR 57.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... connecting to the power source, and in nonelectric blasting prior to attaching an initiating device, all... them from concussion (shock wave), flying material, and gases. (f) Before firing a blast— (1)...

  19. 30 CFR 56.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... notify the appropriate MSHA district office. (e) In electric blasting prior to connecting to the power... (shock wave), flying material, and gases. (f) Before firing a blast— (1) Ample warning shall be given...

  20. 30 CFR 57.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... connecting to the power source, and in nonelectric blasting prior to attaching an initiating device, all... them from concussion (shock wave), flying material, and gases. (f) Before firing a blast— (1)...

  1. 30 CFR 56.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... notify the appropriate MSHA district office. (e) In electric blasting prior to connecting to the power... (shock wave), flying material, and gases. (f) Before firing a blast— (1) Ample warning shall be given...

  2. 30 CFR 57.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... connecting to the power source, and in nonelectric blasting prior to attaching an initiating device, all... them from concussion (shock wave), flying material, and gases. (f) Before firing a blast— (1)...

  3. 30 CFR 57.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... connecting to the power source, and in nonelectric blasting prior to attaching an initiating device, all... them from concussion (shock wave), flying material, and gases. (f) Before firing a blast— (1)...

  4. 30 CFR 56.6306 - Loading, blasting, and security.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... notify the appropriate MSHA district office. (e) In electric blasting prior to connecting to the power... (shock wave), flying material, and gases. (f) Before firing a blast— (1) Ample warning shall be given...

  5. A Multi-Mode Shock Tube for Investigation of Blast-Induced Traumatic Brain Injury

    PubMed Central

    Reneer, Dexter V.; Hisel, Richard D.; Hoffman, Joshua M.; Kryscio, Richard J.; Lusk, Braden T.

    2011-01-01

    Abstract Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave

  6. A multi-mode shock tube for investigation of blast-induced traumatic brain injury.

    PubMed

    Reneer, Dexter V; Hisel, Richard D; Hoffman, Joshua M; Kryscio, Richard J; Lusk, Braden T; Geddes, James W

    2011-01-01

    Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components

  7. Experimental Studies of Mitigation Materials for Blast Induced Tbi

    NASA Astrophysics Data System (ADS)

    Alley, M. D.; Son, S. F.; Christou, G.; Goel, R.; Young, L.

    2009-12-01

    The objective of this experimental study is to compare the effects of various materials obstructing the flow of a blast wave and the ability of the material to reduce the damage caused by the blast. Several methods of energy transfer in blast wave flows are expected including: material interfaces with impedance mismatches, density changes in a given material, internal shearing, and particle fracture. Our hypothesis is that the greatest energy transfer within the obstructing material will yield the greatest mitigation effects to the blast. Sample configurations of foam were varied to introduce material interfaces and filler materials with varying densities and impedances (liquids and powders). The samples were dynamically loaded using a small scale blast produced by an explosive driven shock tube housing gram-scale explosive charges. The transmitted blast profiles were analyzed for variations in impulse characteristics and frequency components as compared to standard free field profiles. The results showed a rounding effect of the transmitted blast profile for all samples with the effects of the high density fillers surpassing all others tested. These results lead to a conclusion that low porosity, high density materials offer superior attenuation by reducing air blast features and spatially distributing the transmitted wave.

  8. Automated Blast Cleaner

    NASA Technical Reports Server (NTRS)

    Pickett, Isaiah R.; Yulfo, Alyce R.

    1992-01-01

    Automatic grit-blasting machine removes melted-layer residue from electrical-discharge-machined surfaces of turbine blades. Automatic control system of machine provides steady flow of grit and maintains blast nozzles at proper distance and in correct orientation perpendicular to surface being blasted, regardless of contour. Eliminates localized excessive blasting and consequent excessive removal of underlying material, blasting of adjacent surfaces, and missed areas.

  9. Assessment of total efficiency in adiabatic engines

    NASA Astrophysics Data System (ADS)

    Mitianiec, W.

    2016-09-01

    The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.

  10. Graph isomorphism and adiabatic quantum computing

    NASA Astrophysics Data System (ADS)

    Gaitan, Frank; Clark, Lane

    2014-02-01

    In the graph isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G →G'. If yes, then G and G' are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap Δ (N) separating the ground and first-excited states in the limit of large problem size N ≫1. Calculating Δ (N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.

  11. Adiabatic Heat of Hydration Calorimetric Measurements for Reference Saltstone Waste

    SciTech Connect

    Bollinger, James

    2006-01-12

    The production of nuclear materials for weapons, medical, and space applications from the mid-1950's through the late-1980's at the Savannah River Site (SRS) generated approximately 35 million gallons of liquid high-level radioactive waste, which is currently being processed into vitrified glass for long-term storage. Upstream of the vitrification process, the waste is separated into three components: high activity insoluble sludge, high activity insoluble salt, and very low activity soluble salts. The soluble salt represents 90% of the 35 million gallons of overall waste and is processed at the SRS Saltstone Facility, where it mixed with cement, blast furnace slag, and flyash, creating a grout-like mixture. The resulting grout is pumped into aboveground storage vaults, where it hydrates into concrete monoliths, called saltstone, thus immobilizing the low-level radioactive salt waste. As the saltstone hydrates, it generates heat that slowly diffuses out of the poured material. To ensure acceptable grout properties for disposal and immobilization of the salt waste, the grout temperature must not exceed 95 C during hydration. Adiabatic calorimetric measurements of the heat generated for a representative sample of saltstone were made to determine the time-dependent heat source term. These measurements subsequently were utilized as input to a numerical conjugate heat transfer model to determine the expected peak temperatures for the saltstone vaults.

  12. Shortcuts to adiabaticity in quantum many-body systems: a quantum dynamical microscope

    NASA Astrophysics Data System (ADS)

    Del Campo, Adolfo

    2014-03-01

    The evolution of a quantum system induced by a shortcut to adiabaticity mimics the adiabatic dynamics without the requirement of slow driving. Engineering it involves diagonalizing the instantaneous Hamiltonian of the system and results in the need of auxiliary non-local interactions for matter-waves. Here experimentally realizable driving protocols are found for a large class of single-particle, many-body, and non-linear systems without demanding the spectral properties as an input. The method is applied to the expansion of a trapped ultracold gas which spatially scales up the size of the cloud while conserving the quantum correlations of the initial many-body state. This shortcut to adiabatic expansions acts as a quantum dynamical microscope.

  13. Separation of enantiomers by ultraviolet laser pulses in H2POSH: π pulses versus adiabatic transitions

    NASA Astrophysics Data System (ADS)

    González, Leticia; Kröner, Dominik; Solá, Ignacio R.

    2001-08-01

    Different strategies to separate enantiomers from a racemate using analytical laser pulses in the ultraviolet frequency domain are proposed for the prototype model system H2POSH. Wave-packet propagations on ab initio ground- and electronic-excited state potentials show that it is possible to produce 100% of enantiomeric excess in a sub-picosecond time scale using a sequence of π and half-π pulses. Alternatively, the previous transitions can be substituted by adiabatic counterparts, using chirped laser pulses and a half-STIRAP (stimulated Raman adiabatic passage) method which only transfers half of the population between appropriate levels. Such an overall adiabatic mechanism gains stability concerning the pulse areas and frequencies at the expense of introducing new control variables, like the chirp and time delay.

  14. Fermion-dimer scattering using an impurity lattice Monte Carlo approach and the adiabatic projection method

    NASA Astrophysics Data System (ADS)

    Elhatisari, Serdar; Lee, Dean

    2014-12-01

    We present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use Lüscher's finite-volume relations to determine the s -wave, p -wave, and d -wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.

  15. Mixing Effect in Internal Blast

    NASA Astrophysics Data System (ADS)

    Granholm, R. H.; Sandusky, H. W.

    2009-12-01

    Detonation product gases are usually assumed to be completely mixed with an existing atmosphere by the time a peak quasi-static pressure (Pqs) is reached within an enclosed internal blast environment. With incomplete mixing, however, comes a loss in pressure from unburned fuel as well as a previously unrecognized source of error: heat capacity of the gas increases substantially with temperature, providing an energy sink in regions of unmixed hot gas. Our objective was to look at the extent of mixing by measuring gas temperature at several locations within a blast chamber at the time of peak Pqs. We recorded ranges of up to 400° C depending on charge location within the chamber, which is presumed to affect turbulence and mixing. Losses in peak Pqs of up to 13% may be attributed to this mixing effect for 1-kg Pentolite charges in a 62-m3 chamber in the simple geometries tested. A reasonably accurate Pqs may be extracted from blast wave reverberations in a chamber, allowing a closer look at effects such as gas mixing and consistency among multiple gages. These results point to an explanation for missing energy and a better understanding of heat flow in internal blast.

  16. Low-Level Primary Blast Causes Acute Ocular Trauma in Rabbits.

    PubMed

    Jones, Kirstin; Choi, Jae-Hyek; Sponsel, William E; Gray, Walt; Groth, Sylvia L; Glickman, Randolph D; Lund, Brian J; Reilly, Matthew A

    2016-07-01

    The objective of this study was to determine whether clinically significant ocular trauma can be induced by a survivable isolated primary blast using a live animal model. Both eyes of 18 Dutch Belted rabbits were exposed to various survivable low-level blast overpressures in a large-scale shock tube simulating a primary blast similar to an improvised explosive device. Eyes of the blast-exposed rabbits (as well as five control rabbits) were thoroughly examined before and after blast to detect changes. Clinically significant changes in corneal thickness arose immediately after blast and were sustained through 48 h, suggesting possible disruption of endothelial function. Retinal thickness (RT) increased with increasing specific impulse immediately after exposure. Intraocular pressure (IOP) was inversely correlated with the specific impulse of the blast wave. These findings clearly indicate that survivable primary blast causes ocular injuries with likely visual functional sequelae of clinical and military relevance.

  17. Energy efficiency of adiabatic superconductor logic

    NASA Astrophysics Data System (ADS)

    Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki

    2015-01-01

    Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2.

  18. Adiabatic approximation for the density matrix

    NASA Astrophysics Data System (ADS)

    Band, Yehuda B.

    1992-05-01

    An adiabatic approximation for the Liouville density-matrix equation which includes decay terms is developed. The adiabatic approximation employs the eigenvectors of the non-normal Liouville operator. The approximation is valid when there exists a complete set of eigenvectors of the non-normal Liouville operator (i.e., the eigenvectors span the density-matrix space), the time rate of change of the Liouville operator is small, and an auxiliary matrix is nonsingular. Numerical examples are presented involving efficient population transfer in a molecule by stimulated Raman scattering, with the intermediate level of the molecule decaying on a time scale that is fast compared with the pulse durations of the pump and Stokes fields. The adiabatic density-matrix approximation can be simply used to determine the density matrix for atomic or molecular systems interacting with cw electromagnetic fields when spontaneous emission or other decay mechanisms prevail.

  19. Adiabaticity and viscosity in deep mantle convection

    NASA Technical Reports Server (NTRS)

    Quareni, F.; Yuen, D. A.; Saari, M. R.

    1986-01-01

    A study has been conducted of steady convection with adiabatic and viscous heating for variable viscosity in the Boussinesq limit using the mean-field theory. A strong nonlinear coupling is found between the thermodynamic constants governing adiabatic heating and the rheological parameters. The range of rheological values for which adiabaticity would occur throughout the mantle has been established. Too large an activation volume, greater than 6 cu cm/mol for the cases examined, would produce unreasonably high temperature at the bottom of the mantle (greater than 6000 K) and superadiabatic gradients, especially in the lower mantle. Radiogenic heating plays a profound role in controlling dynamically mantle temperatures. Present values for the averaged mantle heat production would yield objectionably high temperatures in the lower mantle.

  20. Nonadiabatic exchange dynamics during adiabatic frequency sweeps

    NASA Astrophysics Data System (ADS)

    Barbara, Thomas M.

    2016-04-01

    A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.

  1. Comparison of Some Blast Vibration Predictors for Blasting in Underground Drifts and Some Observations

    NASA Astrophysics Data System (ADS)

    Bhagwat, Vaibhab Pramod; Dey, Kaushik

    2016-04-01

    Drilling and blasting are the most economical excavation techniques in underground drifts driven through hard rock formation. Burn cut is the most popular drill pattern, used in this case, to achieve longer advance per blast round. The ground vibration generated due to the propagation of blast waves on the detonation of explosive during blasting is the principal cause for structural and rock damage. Thus, ground vibration is a point of concern for the blasting engineers. The ground vibration from a blast is measured using a seismograph placed at the blast monitoring station. The measured vibrations, in terms of peak particle velocity, are related to the maximum charge detonated at one instant and the distance of seismograph from the blast point. The ground vibrations from a number of blast rounds of varying charge/delay and distances are monitored. A number of scaling factors of these dependencies (viz. Distance and maximum charge/delay) have been proposed by different researchers, namely, square root, cube root, CMRI, Langefors and Kihlstrom, Ghosh-Daemon, Indian standard etc. Scaling factors of desired type are computed for all the measured blast rounds. Regression analysis is carried out between the scaling factors and peak particle velocities to establish the coefficients of the vibration predictor equation. Then, the developed predictor equation is used for designing the blast henceforth. Director General of Mine Safety, India, specified that ground vibrations from eight to ten blast rounds of varying charge/delay and distances should be monitored to develop a predictor equation; however, there is no guideline about the type of scaling factor to be used. Further to this, from the statistical point of view, a regression analysis on a small sample population cannot be accepted without the testing of hypothesis. To show the importance of the above, in this paper, seven scaling factors are considered for blast data set of a hard-rock underground drift using burn

  2. On adiabatic invariant in generalized Galileon theories

    SciTech Connect

    Ema, Yohei; Jinno, Ryusuke; Nakayama, Kazunori; Mukaida, Kyohei E-mail: jinno@hep-th.phys.s.u-tokyo.ac.jp E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp

    2015-10-01

    We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is useful in estimating the expansion law of the universe and also the particle production rate due to the oscillation of the Hubble parameter.

  3. Spontaneous emission in stimulated Raman adiabatic passage

    SciTech Connect

    Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.

    2005-11-15

    This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.

  4. Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials

    NASA Astrophysics Data System (ADS)

    Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.

    2015-12-01

    Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.

  5. Complexity of the Quantum Adiabatic Algorithm

    NASA Technical Reports Server (NTRS)

    Hen, Itay

    2013-01-01

    The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.

  6. Turbulent Density Variations in Non-Adiabatic Interstellar Fluids

    NASA Astrophysics Data System (ADS)

    Higdon, J. C.; Conley, Alex

    1998-05-01

    Analyses of radio scintillation measurements have demonstrated (e.g., Rickett, ARAA, 28, 561, 1990) the existence of ubiquitous turbulent density fluctuations in the interstellar medium. Higdon (ApJ, 309, 342, 1986) and Goldreich and Sridhar (ApJ, 438, 763 1995) have modeled successfully these density variations as entropy structures distorted by convection in anisotropic magnetohydrodynamic turbulent flows. However, the interstellar medium is a heterogeneous non-adiabatic fluid whose thermal properties result ( Field, ApJ, 142, 531 1965) from a balance of heating and cooling rates. The effect of the non-adiabatic nature of interstellar fluids on the properties of turbulent cascades to small scales has not been considered previously. We find that in thermally stable fluids that the required balance of heating and cooling decreases the amplitudes of entropy structures independently of their spatial scale. Consequently, we show that if the time scale for turbulent flows to cascade to small scales is significantly greater than the cooling time of an interstellar fluid, the generation of turbulent denisty density variations at large wave numbers is greatly suppressed. Such results constrain possible values for the turbulent outer scale in models of interstellar turbulent flows.

  7. Breakdown of adiabatic electron behavior in expanding magnetic fields

    NASA Astrophysics Data System (ADS)

    Lichko, Emily; Egedal, Jan; Daughton, William

    2015-11-01

    During magnetic reconnection the incoming magnetic flux tubes expand in the inflow region. If this expansion is sufficiently slow the results are well described by a previously developed adiabatic model. Using kinetic simulations in a simple geometry and applying rapid magnetic perturbations, this study investigates the point at which the adiabatic assumption fails. To this end a 2D VPIC simulation was constructed, where the magnetic field in a uniform plasma is perturbed by externally driven currents. By varying the onset speed of the magnetic perturbation and the electron thermal speed, we found a sharp threshold at which this model breaks down. We believe that this point is determined by the time of the magnetic pumping compared to the electron transit time through the region, i.e. ω ~ Ḃ / B ~vthe / L . This threshold was also characterized by the launching of Whistler waves and with time domain structures, such as electron holes and double layers, which agree with those seen during magnetic reconnection and may relate to similar structures in the Van Allen Belts. NSF GEM award 1405166 and NASA grant NNX14AC68G.

  8. Determination of explosive blast loading equivalencies with an explosively driven shock tube

    SciTech Connect

    Jackson, Scott I; Hill, Larry G; Morris, John S

    2009-01-01

    Recently there has been significant interest in evaluating the potential of many different non-ideal energetic materials to cause blast damage. We present a method intended to quantitatively compare the blast loading generated by different energetic materials through use of an explosively driven shock tube. The test explosive is placed at the closed breech end of the tube and initiated with a booster charge. The resulting shock waves are then contained and focused by the tube walls to form a quasi-one-dimensional blast wave. Pressure transducers along the tube wall measure the blast overpressure versus distance from the source and allow the use of the one-dimensional blast scaling relationship to determine the energy deposited into the blast wave per unit mass of test explosive. These values are then compared for different explosives of interest and to other methods of equivalency determination.

  9. Determination of Explosive Blast Loading Equivalencies with AN Explosively Driven Shock Tube

    NASA Astrophysics Data System (ADS)

    Jackson, Scott I.; Morris, John S.; Hill, Larry G.

    2009-12-01

    Recently there has been significant interest in evaluating the potential of many different non-ideal energetic materials to cause blast damage. We present a method intended to quantitatively compare the blast loading generated by different energetic materials through use of an explosively driven shock tube. The test explosive is placed at the closed breech end of the tube and initiated with a booster charge. The resulting shock waves are then contained and focused by the tube walls to form a quasi-one-dimensional blast wave. Pressure transducers along the tube wall measure the blast overpressure versus distance from the source and allow the use of the one-dimensional blast scaling relationship to determine the energy deposited into the blast wave per unit mass of test explosive. These values were measured for C4, ANFO, and two perchlorate explosives. Explosive equivalencies from these values were found to agree with prior theory and experiment.

  10. The effect of a blast on the mandible and teeth: transverse fractures and their management.

    PubMed

    Shuker, Sabri T

    2008-10-01

    Transverse mandibular fractures caused by blast waves have given us a better understanding of the physical and pathophysiological effects on this anatomical region. The external contour of the mandible, being rounded in parts (en face) and flat in others (lateral) will experience different effects of the blast. Impact of a spherical blast wave will inflict transverse lines of fractures on the mandibular body, and may be associated with transverse shearing of teeth at the cementoenamel junction. Fractures of the mandible caused by blast are different from those in the same region caused by any type of civilian trauma; these are the vertical to the longitudinal axis unlike comminuted fractures caused by shrapnel or bullet injuries. Fractures of the mandibular body by blasts are single or multiple parallel fractures in the lower border, between the apices of the roots and the mandibular lower border. Fractures are broken off by acceleration or deceleration of the blast wave. PMID:18440677

  11. Effectiveness of eye armor during blast loading.

    PubMed

    Bailoor, Shantanu; Bhardwaj, Rajneesh; Nguyen, Thao D

    2015-11-01

    Ocular trauma is one of the most common types of combat injuries resulting from the interaction of military personnel with improvised explosive devices. Ocular blast injury mechanisms are complex, and trauma may occur through various injury mechanisms. However, primary blast injuries (PBI) are an important cause of ocular trauma that may go unnoticed and result in significant damage to internal ocular tissues and visual impairment. Further, the effectiveness of commonly employed eye armor, designed for ballistic and laser protection, in lessening the severity of adverse blast overpressures (BOP) is unknown. In this paper, we employed a three-dimensional (3D) fluid-structure interaction computational model for assessing effectiveness of the eye armor during blast loading on human eyes and validated results against free field blast measurements by Bentz and Grimm (2013). Numerical simulations show that the blast waves focused on the ocular region because of reflections from surrounding facial features and resulted in considerable increase in BOP. We evaluated the effectiveness of spectacles and goggles in mitigating the pressure loading using the computational model. Our results corroborate experimental measurements showing that the goggles were more effective than spectacles in mitigating BOP loading on the eye. Numerical results confirmed that the goggles significantly reduced blast wave penetration in the space between the armor and the eyes and provided larger clearance space for blast wave expansion after penetration than the spectacles. The spectacles as well as the goggles were more effective in reducing reflected BOP at higher charge mass because of the larger decrease in dynamic pressures after the impact. The goggles provided greater benefit of reducing the peak pressure than the spectacles for lower charge mass. However, the goggles resulted in moderate, sustained elevated pressure loading on the eye, that became 50-100% larger than the pressure loading

  12. Effectiveness of eye armor during blast loading.

    PubMed

    Bailoor, Shantanu; Bhardwaj, Rajneesh; Nguyen, Thao D

    2015-11-01

    Ocular trauma is one of the most common types of combat injuries resulting from the interaction of military personnel with improvised explosive devices. Ocular blast injury mechanisms are complex, and trauma may occur through various injury mechanisms. However, primary blast injuries (PBI) are an important cause of ocular trauma that may go unnoticed and result in significant damage to internal ocular tissues and visual impairment. Further, the effectiveness of commonly employed eye armor, designed for ballistic and laser protection, in lessening the severity of adverse blast overpressures (BOP) is unknown. In this paper, we employed a three-dimensional (3D) fluid-structure interaction computational model for assessing effectiveness of the eye armor during blast loading on human eyes and validated results against free field blast measurements by Bentz and Grimm (2013). Numerical simulations show that the blast waves focused on the ocular region because of reflections from surrounding facial features and resulted in considerable increase in BOP. We evaluated the effectiveness of spectacles and goggles in mitigating the pressure loading using the computational model. Our results corroborate experimental measurements showing that the goggles were more effective than spectacles in mitigating BOP loading on the eye. Numerical results confirmed that the goggles significantly reduced blast wave penetration in the space between the armor and the eyes and provided larger clearance space for blast wave expansion after penetration than the spectacles. The spectacles as well as the goggles were more effective in reducing reflected BOP at higher charge mass because of the larger decrease in dynamic pressures after the impact. The goggles provided greater benefit of reducing the peak pressure than the spectacles for lower charge mass. However, the goggles resulted in moderate, sustained elevated pressure loading on the eye, that became 50-100% larger than the pressure loading

  13. Neuropathology of explosive blast traumatic brain injury.

    PubMed

    Magnuson, John; Leonessa, Fabio; Ling, Geoffrey S F

    2012-10-01

    During the conflicts of the Global War on Terror, which are Operation Enduring Freedom (OEF) in Afghanistan and Operation Iraqi Freedom (OIF), there have been over a quarter of a million diagnosed cases of traumatic brain injury (TBI). The vast majority are due to explosive blast. Although explosive blast TBI (bTBI) shares many clinical features with closed head TBI (cTBI) and penetrating TBI (pTBI), it has unique features, such as early cerebral edema and prolonged cerebral vasospasm. Evolving work suggests that diffuse axonal injury (DAI) seen following explosive blast exposure is different than DAI from focal impact injury. These unique features support the notion that bTBI is a separate and distinct form of TBI. This review summarizes the current state of knowledge pertaining to bTBI. Areas of discussion are: the physics of explosive blast generation, blast wave interaction with the bony calvarium and brain tissue, gross tissue pathophysiology, regional brain injury, and cellular and molecular mechanisms of explosive blast neurotrauma.

  14. Computer modeling of thoracic response to blast.

    PubMed

    Stuhmiller, J H; Chuong, C J; Phillips, Y Y; Dodd, K T

    1988-01-01

    Primary blast injury affects the gas-containing structures of the body. Damage to the lungs with resultant respiratory insufficiency and arterial embolization of air from alveolar pulmonary venous fistulae is the predominant cause of morbidity and mortality following high-level blast exposure. In an effort to generate a widely applicable damage-risk criterion for thoracic injury from blast we are developing a complex computer finite element model (FEM) of the thorax. Taking an engineering approach, a horizontal cross-section of the thorax is divided into small discrete units (finite elements) of homogeneous structure. The necessary physical properties (density, bulk modulus, etc.) are then determined for each element. Specifying the material constants and geometry of the elements, the computer can load the surface of the structure with some force-time function (blast pressure-time history) and calculate the resultant physical events such as displacement, compression, stress, strain, etc. Computer predictions of pressure wave phenomena in the lung parenchyma are compared with trans-bronchially measured pressures in blast-exposed animals. The model should prove useful in assessing the risk of blast injury in diverse overpressure environments and may give insight into pathophysiologic mechanisms and strategies for protection.

  15. Towards fault tolerant adiabatic quantum computation.

    PubMed

    Lidar, Daniel A

    2008-04-25

    I show how to protect adiabatic quantum computation (AQC) against decoherence and certain control errors, using a hybrid methodology involving dynamical decoupling, subsystem and stabilizer codes, and energy gaps. Corresponding error bounds are derived. As an example, I show how to perform decoherence-protected AQC against local noise using at most two-body interactions.

  16. Dynamical aspects of an adiabatic piston.

    PubMed

    Munakata, T; Ogawa, H

    2001-09-01

    Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.

  17. Adiabatic reversible compression: a molecular view

    NASA Astrophysics Data System (ADS)

    Miranda, E. N.

    2002-07-01

    The adiabatic compression (or expansion) of an ideal gas has been analysed. Using the kinetic theory of gases the usual relation between temperature and volume is obtained, while textbooks follow a thermodynamic approach. In this way we show, once again, the agreement between a macroscopic view (thermodynamics) and a microscopic one (kinetic theory).

  18. Dynamical aspects of an adiabatic piston

    NASA Astrophysics Data System (ADS)

    Munakata, Toyonori; Ogawa, Hideki

    2001-09-01

    Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.

  19. Adiabatic Compression in a Fire Syringe.

    ERIC Educational Resources Information Center

    Hayn, Carl H.; Baird, Scott C.

    1985-01-01

    Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)

  20. Time dependence of adiabatic particle number

    NASA Astrophysics Data System (ADS)

    Dabrowski, Robert; Dunne, Gerald V.

    2016-09-01

    We consider quantum field theoretic systems subject to a time-dependent perturbation, and discuss the question of defining a time-dependent particle number not just at asymptotic early and late times, but also during the perturbation. Naïvely, this is not a well-defined notion for such a nonequilibrium process, as the particle number at intermediate times depends on a basis choice of reference states with respect to which particles and antiparticles are defined, even though the final late-time particle number is independent of this basis choice. The basis choice is associated with a particular truncation of the adiabatic expansion. The adiabatic expansion is divergent, and we show that if this divergent expansion is truncated at its optimal order, a universal time dependence is obtained, confirming a general result of Dingle and Berry. This optimally truncated particle number provides a clear picture of quantum interference effects for perturbations with nontrivial temporal substructure. We illustrate these results using several equivalent definitions of adiabatic particle number: the Bogoliubov, Riccati, spectral function and Schrödinger picture approaches. In each approach, the particle number may be expressed in terms of the tiny deviations between the exact and adiabatic solutions of the Ermakov-Milne equation for the associated time-dependent oscillators.

  1. Apparatus to Measure Adiabatic and Isothermal Processes.

    ERIC Educational Resources Information Center

    Lamb, D. W.; White, G. M.

    1996-01-01

    Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…

  2. Adiabatic Mass Parameters for Spontaneous Fission

    SciTech Connect

    Baran, A.; Sheikh, J. A.; Nazarewicz, Witold

    2009-01-01

    The collective mass tensor derived from the adiabatic time-dependent Hartree-Fock-Bogoliubov theory, perturbative cranking approximation, and the Gaussian overlap approximation to the generator-coordinate method is discussed. Illustrative calculations are carried out for ^{252}Fm using the nuclear density functional theory with Skyrme interaction SkM* and seniority pairing.

  3. Robust entanglement via optomechanical dark mode: adiabatic scheme

    NASA Astrophysics Data System (ADS)

    Tian, Lin; Wang, Ying-Dan; Huang, Sumei; Clerk, Aashish

    2013-03-01

    Entanglement is a powerful resource for studying quantum effects in macroscopic objects and for quantum information processing. Here, we show that robust entanglement between cavity modes with distinct frequencies can be generated via a mechanical dark mode in an optomechanical quantum interface. Due to quantum interference, the effect of the mechanical noise is cancelled in a way that is similar to the electromagnetically induced transparency. We derive the entanglement in the strong coupling regime by solving the quantum Langevin equation using a perturbation theory approach. The entanglement in the adiabatic scheme is then compared with the entanglement in the stationary state scheme. Given the robust entanglement schemes and our previous schemes on quantum wave length conversion, the optomechanical interface hence forms an effective building block for a quantum network. This work is supported by DARPA-ORCHID program, NSF-DMR-0956064, NSF-CCF-0916303, and NSF-COINS.

  4. An automatic MEG low-frequency source imaging approach for detecting injuries in mild and moderate TBI patients with blast and non-blast causes.

    PubMed

    Huang, Ming-Xiong; Nichols, Sharon; Robb, Ashley; Angeles, Annemarie; Drake, Angela; Holland, Martin; Asmussen, Sarah; D'Andrea, John; Chun, Won; Levy, Michael; Cui, Li; Song, Tao; Baker, Dewleen G; Hammer, Paul; McLay, Robert; Theilmann, Rebecca J; Coimbra, Raul; Diwakar, Mithun; Boyd, Cynthia; Neff, John; Liu, Thomas T; Webb-Murphy, Jennifer; Farinpour, Roxanna; Cheung, Catherine; Harrington, Deborah L; Heister, David; Lee, Roland R

    2012-07-16

    Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild (and some moderate) TBI can be difficult to diagnose because the injuries are often not detectable on conventional MRI or CT. Injured brain tissues in TBI patients generate abnormal low-frequency magnetic activity (ALFMA, peaked at 1-4 Hz) that can be measured and localized by magnetoencephalography (MEG). We developed a new automated MEG low-frequency source imaging method and applied this method in 45 mild TBI (23 from combat-related blasts, and 22 from non-blast causes) and 10 moderate TBI patients (non-blast causes). Seventeen of the patients with mild TBI from blasts had tertiary injuries resulting from the blast. The results show our method detected abnormalities at the rates of 87% for the mild TBI group (blast-induced plus non-blast causes) and 100% for the moderate group. Among the mild TBI patients, the rates of abnormalities were 96% and 77% for the blast and non-blast TBI groups, respectively. The spatial characteristics of abnormal slow-wave generation measured by Z scores in the mild blast TBI group significantly correlated with those in non-blast mild TBI group. Among 96 cortical regions, the likelihood of abnormal slow-wave generation was less in the mild TBI patients with blast than in the mild non-blast TBI patients, suggesting possible protective effects due to the military helmet and armor. Finally, the number of cortical regions that generated abnormal slow-waves correlated significantly with the total post-concussive symptom scores in TBI patients. This study provides a foundation for using MEG low-frequency source imaging to support the clinical diagnosis of TBI. PMID:22542638

  5. Distinguishing Realistic Military Blasts from Firecrackers in Mitigation Studies of Blast Induced Traumatic Brain Injury

    SciTech Connect

    Moss, W C; King, M J; Blackman, E G

    2011-01-21

    In their Contributed Article, Nyein et al. (1,2) present numerical simulations of blast waves interacting with a helmeted head and conclude that a face shield may significantly mitigate blast induced traumatic brain injury (TBI). A face shield may indeed be important for future military helmets, but the authors derive their conclusions from a much smaller explosion than typically experienced on the battlefield. The blast from the 3.16 gm TNT charge of (1) has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 10 atm, 0.25 ms, and 3.9 psi-ms at the front of the head (14 cm from charge), and 1.4 atm, 0.32 ms, and 1.7 psi-ms at the back of a typical 20 cm head (34 cm from charge). The peak pressure of the wave decreases by a factor of 7 as it traverses the head. The blast conditions are at the threshold for injury at the front of the head, but well below threshold at the back of the head (4). The blast traverses the head in 0.3 ms, roughly equal to the positive phase duration of the blast. Therefore, when the blast reaches the back of the head, near ambient conditions exist at the front. Because the headform is so close to the charge, it experiences a wave with significant curvature. By contrast, a realistic blast from a 2.2 kg TNT charge ({approx} an uncased 105 mm artillery round) is fatal at an overpressure of 10 atm (4). For an injury level (4) similar to (1), a 2.2 kg charge has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 2.1 atm, 2.3 ms, and 18 psi-ms at the front of the head (250 cm from charge), and 1.8 atm, 2.5 ms, and 16.8 psi-ms at the back of the head (270 cm from charge). The peak pressure decreases by only a factor of 1.2 as it traverses the head. Because the 0.36 ms traversal time is much smaller than the positive phase duration, pressures on the head become relatively uniform when the blast reaches the back of the head. The larger standoff implies

  6. Adiabatic burst evaporation from bicontinuous nanoporous membranes

    PubMed Central

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk

    2015-01-01

    Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

  7. Shock wave interaction with interfaces between materials having different acoustic impedances

    NASA Astrophysics Data System (ADS)

    Hosseini, H.; Moosavi-Nejad, S.; Akiyama, H.; Menezes, V.

    2014-03-01

    We experimentally examined interaction of blast waves with water-air/air-water interfaces through high-speed-real-time visualization and measurement of pressure across the waves. The underwater shock wave, which was expected to reflect totally at the water-air interface, was observed transmitting a shock front to air. Transmission of a blast wave from air to water was also visualized and evaluated. Underwater shock waves are used in several medical/biological procedures, where such unforeseen transmissions can result in detriments. The details provide a guideline to evaluate blast wave transmissions, which can induce tissue and brain injuries. The results explain mechanisms behind blast-induced traumatic brain injury.

  8. Rock blasting environmental impacts

    SciTech Connect

    Agreda, C.

    1995-12-31

    The rock blasting environmental impacts such as: flyrock, ground vibrations, air-blast, and/or noise, dust and fumes are identified and mentioned. Some comments on the correction factors that might be taken into consideration to calculate the initial velocity and the maximum projection of the rock fragments are mentioned as well. The blast fumes causes, its alleviation and protective measures are identified, described and discussed. To mitigate, minimize and/or avoid blast fumes, the AN/FO, Al/AN/FO and S/AN/FO dry blasting agents optimum equations are developed, discussed and recommended.

  9. Modern BLAST Programs

    NASA Astrophysics Data System (ADS)

    Ma, Jian; Zhang, Louxin

    The Basic Local Alignment Search Tool (BLAST) is arguably the most widely used program in bioinformatics. By sacrificing sensitivity for speed, it makes sequence comparison practical on huge sequence databases currently available. The original version of BLAST was developed in 1990. Since then it has spawned a variant of specialized programs. This chapter surveys the development of BLAST and BLAST-like programs for homology search, discusses alignment statistics that are used in assessment of reported matches in BLAST, and provides the reader with guidance to select appropriate programs and set proper parameters to match research requirements.

  10. Non-adiabatic perturbations in multi-component perfect fluids

    SciTech Connect

    Koshelev, N.A.

    2011-04-01

    The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.

  11. Frequency offset dependence of adiabatic rotating frame relaxation rate constants: relevance to MRS investigations of metabolite dynamics in vivo

    PubMed Central

    Mangia, Silvia; Liimatainen, Timo; Garwood, Michael; Tkac, Ivan; Henry, Pierre-Gilles; Deelchand, Dinesh; Michaeli, Shalom

    2011-01-01

    In this work, we investigated the frequency-offset dependence of the rotating frame longitudinal (R1ρ) and transverse (R2ρ) relaxation rate constants when using hyperbolic-secant adiabatic full passage pulses or continuous-wave spin-lock irradiation. Phantom and in vivo measurements were performed to validate theoretical predictions of the dominant relaxation mechanisms existing during adiabatic full passage pulses when using different settings of the frequency offset relative to the carrier. In addition, adiabatic R1ρ and R2ρ values of total creatine and N-acetylaspartate were measured in vivo from the human brain at 4 T. When the continuous-wave pulse power was limited to safe specific absorption rates for humans, simulations revealed a strong dependence of R1ρ and R2ρ values on the frequency offset for both dipolar interactions and anisochronous exchange mechanisms. By contrast, theoretical and experimental results showed adiabatic R1ρ and R2ρ values to be practically invariant within the large subregion of the bandwidth of the hyperbolic-secant pulse where complete inversion was achieved. However, adiabatic R1ρ and R2ρ values of the methyl protons of total creatine (at 3.03 ppm) were almost doubled when compared with those of the methyl protons of N-acetylaspartate (at 2.01 ppm) in spite of the fact that these resonances were in the flat region of the inversion band of the adiabatic full passage pulses. We conclude that differences in adiabatic R1ρ and R2ρ values of human brain metabolites are not a result of their chemical shifts, but instead reflect differences in dynamics. PMID:21264976

  12. Blast related neurotrauma: a review of cellular injury.

    PubMed

    Leung, Lai Yee; VandeVord, Pamela J; Dal Cengio, Alessandra Leonardi; Bir, Cynthia; Yang, King H; King, Albert I

    2008-09-01

    Historically, blast overpressure is known to affect primarily gas-containing organs such as the lung and ear. More recent interests focus on its ability to cause damage to solid organs such as the brain, resulting in neurological disorders. Returning veterans exposed to blast but without external injuries are being diagnosed with mild traumatic brain injury (Warden 2006) and with cortical dysfunction (Cernak et al 1999). Decades of studies have been conducted to elucidate the effects of primary blast wave on the central nervous system. These studies were mostly concerned with systemic effects (Saljo et al 2000-2003; Kaur et al 1995-1997, 1999; Cernak et al 1996, 2001). The molecular mechanism of blast-induced neurotrauma is still poorly understood. This paper reviews studies related to primary blast injury to the nervous system, particularly at the cellular level. It starts with a general discussion of primary blast injury and blast wave physics, followed by a review of the literature related to 1) the blast wave/body interaction, 2) injuries to the peripheral nervous system, 3) injuries to the central nervous system, and 4) injury criteria. Finally, some of our preliminary data on cellular injury from in vitro and in vivo studies are presented. Specifically, we report on the effects of overpressure on astrocytes. In the discussion, possible mechanisms of blast-related brain injury are discussed, as well as the concerns and limitations of the published studies. A clearer understanding of the injury mechanisms at both the molecular and macroscopic (organ) level will lead to the development of new treatment, diagnosis and preventive measures. PMID:18751525

  13. Adiabatic quantum simulation of quantum chemistry.

    PubMed

    Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán

    2014-10-13

    We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.

  14. Quantum adiabatic evolution with energy degeneracy levels

    NASA Astrophysics Data System (ADS)

    Zhang, Qi

    2016-01-01

    A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.

  15. Adiabatic quantum optimization for associative memory recall

    SciTech Connect

    Seddiqi, Hadayat; Humble, Travis S.

    2014-12-22

    Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.

  16. Adiabatic quantum optimization for associative memory recall

    DOE PAGES

    Seddiqi, Hadayat; Humble, Travis S.

    2014-12-22

    Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less

  17. Trapped Ion Quantum Computation by Adiabatic Passage

    SciTech Connect

    Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.

    2008-11-07

    We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.

  18. Ramsey numbers and adiabatic quantum computing.

    PubMed

    Gaitan, Frank; Clark, Lane

    2012-01-01

    The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.

  19. Adiabatic Heating of Contracting Turbulent Fluids

    NASA Astrophysics Data System (ADS)

    Robertson, Brant; Goldreich, Peter

    2012-05-01

    Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases "adiabatically heat," experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.

  20. ADIABATIC HEATING OF CONTRACTING TURBULENT FLUIDS

    SciTech Connect

    Robertson, Brant; Goldreich, Peter

    2012-05-10

    Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases 'adiabatically heat', experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.

  1. Adiabatic Quantum Simulation of Quantum Chemistry

    NASA Astrophysics Data System (ADS)

    Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán

    2014-10-01

    We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.

  2. Shortcuts to adiabaticity from linear response theory

    SciTech Connect

    Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian

    2015-10-23

    A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.

  3. Shortcuts to adiabaticity from linear response theory

    DOE PAGES

    Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian

    2015-10-23

    A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less

  4. Siphon flows in isolated magnetic flux tubes. II - Adiabatic flows

    NASA Technical Reports Server (NTRS)

    Montesinos, Benjamin; Thomas, John H.

    1989-01-01

    This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point.

  5. Siphon flows in isolated magnetic flux tubes. II. Adiabatic flows

    SciTech Connect

    Montesinos, B.; Thomas, J.H.

    1989-02-01

    This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point. 15 references.

  6. Computer Code For Turbocompounded Adiabatic Diesel Engine

    NASA Technical Reports Server (NTRS)

    Assanis, D. N.; Heywood, J. B.

    1988-01-01

    Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.

  7. Adiabatic charging of nickel-hydrogen batteries

    NASA Astrophysics Data System (ADS)

    Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna

    1995-02-01

    Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.

  8. Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling

    NASA Technical Reports Server (NTRS)

    Chu, Paul C. W.

    2004-01-01

    The research at Houston was focused on optimizing the design of superconducting magnets for advanced adiabatic demagnetization refrigerators (ADRs), assessing the feasibility of using high temperature superconducting (HTS) magnets in ADRs in the future, and developing techniques to deposit HTS thin and thick films on high strength, low thermal conductivity substrates for HTS magnet leads. Several approaches have been tested for the suggested superconducting magnets.

  9. Random matrix model of adiabatic quantum computing

    SciTech Connect

    Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.

    2005-05-15

    We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.

  10. Non-adiabatic dark fluid cosmology

    SciTech Connect

    Hipólito-Ricaldi, W.S.; Velten, H.E.S.; Zimdahl, W. E-mail: velten@cce.ufes.br

    2009-06-01

    We model the dark sector of the cosmic substratum by a viscous fluid with an equation of state p = −ζΘ, where Θ is the fluid-expansion scalar and ζ is the coefficient of bulk viscosity for which we assume a dependence ζ∝ρ{sup ν} on the energy density ρ. The homogeneous and isotropic background dynamics coincides with that of a generalized Chaplygin gas with equation of state p = −A/ρ{sup α}. The perturbation dynamics of the viscous model, however, is intrinsically non-adiabatic and qualitatively different from the Chaplygin-gas case. In particular, it avoids short-scale instabilities and/or oscillations which apparently have ruled out unified models of the Chaplygin-gas type. We calculate the matter power spectrum and demonstrate that the non-adiabatic model is compatible with the data from the 2dFGRS and the SDSS surveys. A χ{sup 2}-analysis shows, that for certain parameter combinations the viscous-dark-fluid (VDF) model is well competitive with the ΛCDM model. These results indicate that non-adiabatic unified models can be seen as potential contenders for a General-Relativity-based description of the cosmic substratum.

  11. Toxicology of blast overpressure.

    PubMed

    Elsayed, N M

    1997-07-25

    Blast overpressure (BOP) or high energy impulse noise, is the sharp instantaneous rise in ambient atmospheric pressure resulting from explosive detonation or firing of weapons. Blasts that were once confined to military and to a lesser extent, occupational settings, are becoming more universal as the civilian population is now increasingly at risk of exposure to BOP from terrorist bombings that are occurring worldwide with greater frequency. Exposure to incident BOP waves can cause auditory and non-auditory damage. The primary targets for BOP damage are the hollow organs, ear, lung and gastrointestinal tract. In addition, solid organs such as heart, spleen and brain can also be injured upon exposure. However, the lung is more sensitive to damage and its injury can lead to death. The pathophysiological responses, and mortality have been extensively studied, but little attention, was given to the biochemical manifestations, and molecular mechanism(s) of injury. The injury from BOP has been, generally, attributed to its external physical impact on the body causing internal mechanical damage. However, a new hypothesis has been proposed based on experiments conducted in the Department of Respiratory Research, Walter Reed Army Institute of Research, and later in the Department of Occupational Health, University of Pittsburgh. This hypothesis suggests that subtle biochemical changes namely, free radical-mediated oxidative stress occur and contribute to BOP-induced injury. Understanding the etiology of these changes may shed new light on the molecular mechanism(s) of injury, and can potentially offer new strategies for treatment. In this symposium. BOP research involving auditory, non-auditory, physiological, pathological, behavioral, and biochemical manifestations as well as predictive modeling and current treatment modalities of BOP-induced injury are discussed.

  12. Toxicology of blast overpressure.

    PubMed

    Elsayed, N M

    1997-07-25

    Blast overpressure (BOP) or high energy impulse noise, is the sharp instantaneous rise in ambient atmospheric pressure resulting from explosive detonation or firing of weapons. Blasts that were once confined to military and to a lesser extent, occupational settings, are becoming more universal as the civilian population is now increasingly at risk of exposure to BOP from terrorist bombings that are occurring worldwide with greater frequency. Exposure to incident BOP waves can cause auditory and non-auditory damage. The primary targets for BOP damage are the hollow organs, ear, lung and gastrointestinal tract. In addition, solid organs such as heart, spleen and brain can also be injured upon exposure. However, the lung is more sensitive to damage and its injury can lead to death. The pathophysiological responses, and mortality have been extensively studied, but little attention, was given to the biochemical manifestations, and molecular mechanism(s) of injury. The injury from BOP has been, generally, attributed to its external physical impact on the body causing internal mechanical damage. However, a new hypothesis has been proposed based on experiments conducted in the Department of Respiratory Research, Walter Reed Army Institute of Research, and later in the Department of Occupational Health, University of Pittsburgh. This hypothesis suggests that subtle biochemical changes namely, free radical-mediated oxidative stress occur and contribute to BOP-induced injury. Understanding the etiology of these changes may shed new light on the molecular mechanism(s) of injury, and can potentially offer new strategies for treatment. In this symposium. BOP research involving auditory, non-auditory, physiological, pathological, behavioral, and biochemical manifestations as well as predictive modeling and current treatment modalities of BOP-induced injury are discussed. PMID:9217311

  13. Primary blast injury causes cognitive impairments and hippocampal circuit alterations.

    PubMed

    Beamer, Matthew; Tummala, Shanti R; Gullotti, David; Kopil, Catherine; Gorka, Samuel; Ted Abel; Bass, Cameron R Dale; Morrison, Barclay; Cohen, Akiva S; Meaney, David F

    2016-09-01

    Blast-induced traumatic brain injury (bTBI) and its long term consequences are a major health concern among veterans. Despite recent work enhancing our knowledge about bTBI, very little is known about the contribution of the blast wave alone to the observed sequelae. Herein, we isolated its contribution in a mouse model by constraining the animals' heads during exposure to a shockwave (primary blast). Our results show that exposure to primary blast alone results in changes in hippocampus-dependent behaviors that correspond with electrophysiological changes in area CA1 and are accompanied by reactive gliosis. Specifically, five days after exposure, behavior in an open field and performance in a spatial object recognition (SOR) task were significantly different from sham. Network electrophysiology, also performed five days after injury, demonstrated a significant decrease in excitability and increase in inhibitory tone. Immunohistochemistry for GFAP and Iba1 performed ten days after injury showed a significant increase in staining. Interestingly, a threefold increase in the impulse of the primary blast wave did not exacerbate these measures. However, we observed a significant reduction in the contribution of the NMDA receptors to the field EPSP at the highest blast exposure level. Our results emphasize the need to account for the effects of primary blast loading when studying the sequelae of bTBI.

  14. Experimental Studies of Mitigation Materials for Blast Induced TBI

    NASA Astrophysics Data System (ADS)

    Alley, Matthew; Son, Steven

    2009-06-01

    The objective of this experimental study is to compare the effects of various materials obstructing the flow of a blast wave and the ability of the given material to reduce the damage caused by the blast. Several methods of energy transfer in blast wave flows are known or expected including: material interfaces with impedance mismatches, density changes in a given material, internal shearing, and particle fracture. The theory applied to this research is that the greatest energy transfer within the obstructing material will yield the greatest mitigation effects to the blast. Sample configurations of foam were varied to introduce material interfaces and filler materials with varying densities and impedances (liquids and powders). The samples were loaded according to a small scale blast produced by an explosive driven shock tube housing gram-range charges. The transmitted blast profiles were analyzed for variations in impulse characteristics and frequency components as compared to standard free field profiles. The results showed a rounding effect of the transmitted blast profile for all samples with the effects of the low density fillers surpassing all others tested.

  15. Primary blast injury causes cognitive impairments and hippocampal circuit alterations

    PubMed Central

    Beamer, Matthew; Tummala, Shanti R.; Gullotti, David; Kopil, Kathryn; Gorka, Samuel; Abel, Ted; “Dale” Bass, Cameron R.; Morrison, Barclay; Cohen, Akiva S.; Meaney, David F.

    2016-01-01

    Blast-induced traumatic brain injury (bTBI) and its long term consequences are a major health concern among veterans. Despite recent work enhancing our knowledge about bTBI, very little is known about the contribution of the blast wave alone to the observed sequelae. Herein, we isolated its contribution in a mouse model by constraining the animals' heads during exposure to a shockwave (primary blast). Our results show that exposure to primary blast alone results in changes in hippocampus-dependent behaviors that correspond with electro-physiological changes in area CA1 and are accompanied by reactive gliosis. Specifically, five days after exposure, behavior in an open field and performance in a spatial object recognition (SOR) task were significantly different from sham. Network electrophysiology, also performed five days after injury, demonstrated a significant decrease in excitability and increase in inhibitory tone. Immunohistochemistry for GFAP and Iba1 performed ten days after injury showed a significant increase in staining. Interestingly, a threefold increase in the impulse of the primary blast wave did not exacerbate these measures. However, we observed a significant reduction in the contribution of the NMDA receptors to the field EPSP at the highest blast exposure level. Our results emphasize the need to account for the effects of primary blast loading when studying the sequelae of bTBI. PMID:27246999

  16. On the efficiency of semi-closed blast inhibitors

    NASA Astrophysics Data System (ADS)

    Gelfand, B. E.; Silnikov, M. V.; Chernyshov, M. V.

    2010-08-01

    Numerical efficiency analysis of those blast inhibitors (BI) consisting of a vertical cylinder open at the top is presented and compared with the existing data from other authors. It was proven computationally that such low-height “semi-closed” BI do not provide blast wave suppression according to the minimum practical requirements (overpressure and pressure impulse reduction at several times) and, if one wishes to compare, other existing criteria (Bowen injury diagrams and similar guidelines adopted in different countries).

  17. Development of a Liquid Blast Tube Facility for Material Testing

    NASA Astrophysics Data System (ADS)

    Samuelraj, I. Obed; Jagadeesh, G.

    The feasibility of mitigating blast/shock loads using materials such as composites and foams is well known. In order to study their attenuation characteristics and to optimize the mitigation of such loads, use of shock tube to generate an exponentially decaying pressure profile (called blast tube here) is a popular technique. Shock waves in liquids (e.g., water), particularly, are capable of meeting this requirement as they are stronger and also uniform [1].

  18. Blast assessment and optimization for high quarry face-blasting

    SciTech Connect

    Sames, F.; O`Meara, R.

    1996-12-01

    Where applicable, high production benches can improve efficiency in quarrying. Quality control, geological, cost or other considerations might result in the development of quarry benches higher than 30 m and sometimes up to 60 m. Production blasts on high quarry faces require a confident blast design with respect to safety, cost efficiency and minimized environmental effects. Careful pre-blast assessment of the design parameters, blast monitoring of the product performance and the environmental effects and post-blast assessment of the overall blast performance are essential for the successful implementation of the blast design. The blast geometry for high quarry faces and a blast design that often includes multiple explosive charges in a blasthole, make a reliable assessment of the blast parameters difficult. Assessment techniques, their applications and limitations are described and discussed. This will include such methods as blast surveying using laser profiling and borehole deviation measurements, blast monitoring using continuous velocity of detonation measurement systems, high speed photography and seismographs for blast performance and environmental effects. Observations of low frequency airblast and high standard deviations in ground vibration measurements are described and discussed against a background of timing assessment and frequency spectra analysis. Approaches where an optimized design was implemented based on the blast parameter assessment and modeling are presented. An improvement in blast efficiency lies in the combination of blast assessment and blast modeling, whilst adequate documentation supports the process of designing and implementing successful blasts.

  19. An animal-to-human scaling law for blast-induced traumatic brain injury risk assessment

    PubMed Central

    Jean, Aurélie; Nyein, Michelle K.; Zheng, James Q.; Moore, David F.; Joannopoulos, John D.; Radovitzky, Raúl

    2014-01-01

    Despite recent efforts to understand blast effects on the human brain, there are still no widely accepted injury criteria for humans. Recent animal studies have resulted in important advances in the understanding of brain injury due to intense dynamic loads. However, the applicability of animal brain injury results to humans remains uncertain. Here, we use advanced computational models to derive a scaling law relating blast wave intensity to the mechanical response of brain tissue across species. Detailed simulations of blast effects on the brain are conducted for different mammals using image-based biofidelic models. The intensity of the stress waves computed for different external blast conditions is compared across species. It is found that mass scaling, which successfully estimates blast tolerance of the thorax, fails to capture the brain mechanical response to blast across mammals. Instead, we show that an appropriate scaling variable must account for the mass of protective tissues relative to the brain, as well as their acoustic impedance. Peak stresses transmitted to the brain tissue by the blast are then shown to be a power function of the scaling parameter for a range of blast conditions relevant to TBI. In particular, it is found that human brain vulnerability to blast is higher than for any other mammalian species, which is in distinct contrast to previously proposed scaling laws based on body or brain mass. An application of the scaling law to recent experiments on rabbits furnishes the first physics-based injury estimate for blast-induced TBI in humans. PMID:25267617

  20. An animal-to-human scaling law for blast-induced traumatic brain injury risk assessment.

    PubMed

    Jean, Aurélie; Nyein, Michelle K; Zheng, James Q; Moore, David F; Joannopoulos, John D; Radovitzky, Raúl

    2014-10-28

    Despite recent efforts to understand blast effects on the human brain, there are still no widely accepted injury criteria for humans. Recent animal studies have resulted in important advances in the understanding of brain injury due to intense dynamic loads. However, the applicability of animal brain injury results to humans remains uncertain. Here, we use advanced computational models to derive a scaling law relating blast wave intensity to the mechanical response of brain tissue across species. Detailed simulations of blast effects on the brain are conducted for different mammals using image-based biofidelic models. The intensity of the stress waves computed for different external blast conditions is compared across species. It is found that mass scaling, which successfully estimates blast tolerance of the thorax, fails to capture the brain mechanical response to blast across mammals. Instead, we show that an appropriate scaling variable must account for the mass of protective tissues relative to the brain, as well as their acoustic impedance. Peak stresses transmitted to the brain tissue by the blast are then shown to be a power function of the scaling parameter for a range of blast conditions relevant to TBI. In particular, it is found that human brain vulnerability to blast is higher than for any other mammalian species, which is in distinct contrast to previously proposed scaling laws based on body or brain mass. An application of the scaling law to recent experiments on rabbits furnishes the first physics-based injury estimate for blast-induced TBI in humans. PMID:25267617

  1. Non-adiabatic effects on the optical response of driven systems

    NASA Astrophysics Data System (ADS)

    Fregoso, Benjamin M.; Kolodrubetz, Michael; Moore, Joel

    Periodically driven systems have received renewed interest due to their capacity to engineer non-trivial effective Hamiltonians. A characteristic of such systems is how they respond to weak periodicity-breaking drive, as for example when a laser is pulsed instead of continuous wave. We develop semi-classical equations of motion of a wave packet in the presence of electric and magnetic fields which are turned on non-adiabatically. We then show the emergence of significant corrections to electronic collective excitations and optical responses of topological insulator surface states, Weyl metals and semiconductor mono-chalcogenides.

  2. Decoherence and adiabatic transport in semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Switkes, Michael

    2000-10-01

    I present research on ballistic electron transport in lateral GaAs/AlGaAs quantum dots connected to the environment with leads supporting one or more fully transmitting quantum modes. The first part of this dissertation examines electron the phenomena which mediate the transition from quantum mechanical to classical behavior in these quantum dots. Measurements of electron phase coherence time based on the magnitude of weak localization correction are presented as a function both of temperature and of applied bias. The coherence time is found to depend on temperature approximately as a sum of two power laws, tauφ ≈ AT-1 + BT-2, in agreement with the prediction for diffusive two dimensional systems but not with predictions for closed quantum dots or ballistic 2D systems. The effects of a large applied bias can be described with an elevated effective electron temperature calculated from the balance of Joule heating and cooling by Wiedemann-Franz out diffusion of hot electrons. The limits this imposes for quantum dot based technologies are examined through the detailed analysis of a quantum dot magnetometer. The second part of the work presented here focuses on a novel form of electron transport, adiabatic quantum electron pumping, in which a current is driven by cyclic changes in the wave function of a mesoscopic system rather than by an externally imposed bias. After a brief review of other mechanisms which produce a dc current from an ac excitation, measurements of adiabatic pumping are presented. The pumped current (or voltage) is sinusoidal in the phase difference between the two ac voltages deforming the dot potential and fluctuates in both magnitude and direction with small changes in external parameters such as magnetic field. Dependencies of pumping on the strength of the deformations, temperature, and breaking of time-reversal symmetry are also investigated.

  3. A computational study on brain tissue under blast: primary and tertiary blast injuries.

    PubMed

    Rezaei, A; Salimi Jazi, M; Karami, G; Ziejewski, M

    2014-08-01

    In this paper, a biomechanical study of a human head model exposed to blast shock waves followed by a blunt impact with the surface of the enclosing walls of a confined space is carried out. Under blast, the head may experience primary blast injury (PBI) due to exposure to the shockwaves and tertiary blast injury (TeBI) due to a possible blunt impact. We examine the brain response data in a deformable finite element head model in terms of the inflicted stress/pressure, velocity, and acceleration on the brain for several blast scenarios with different intensities. The data will be compared for open space and confined spaces. Following the initial impact of the shock front in the confined space, one can see the fluctuations in biomechanical data due to wave reflections. Although the severity of the PBI and TeBI is dependent on the situation, for the cases studied here, PBI is considerably more pronounced than TeBI in confined spaces. PMID:24515869

  4. Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment

    NASA Astrophysics Data System (ADS)

    Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod

    2016-11-01

    We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.

  5. Characterization of viscoelastic materials for low-magnitude blast mitigation

    NASA Astrophysics Data System (ADS)

    Bartyczak, S.; Mock, W.

    2014-05-01

    Recent research indicates that exposure to low amplitude blast waves, such as IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of the present work is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. The 40-mm-bore gas gun was used as a shock tube to generate blast waves (ranging from 0.5 to 2 bar) in the test fixture mounted on the gun muzzle. A fast opening valve was used to release helium gas from the breech which formed into a blast wave and impacted instrumented targets in the test fixture. Blast attenuation of selected materials was determined through the measurement of stress data in front of and behind the target. Materials evaluated in this research include polyurethane foam from currently fielded US Army and Marine Corps helmets, polyurea 1000, and three hardnesses of Sorbothane (48, 58, and 70 durometer, Shore 00). Polyurea 1000 and 6061-T6 aluminum were used to calibrate the stress gauges.

  6. Characterization of Viscoelastic Materials for Low-Magnitude Blast Mitigation

    NASA Astrophysics Data System (ADS)

    Bartyczak, Susan; Mock, Willis

    2013-06-01

    Recent preliminary research indicates that exposure to low amplitude blast waves, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of this research is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. A 40-mm-bore gas gun is used as a shock tube to generate blast waves (ranging from 5 to 30 psi) in a test fixture mounted at the gun muzzle. A fast opening valve is used to release helium gas from a breech which forms into a blast wave and impacts instrumented targets in the test fixture. Blast attenuation of selected materials is determined through the measurement of pressure and accelerometer data in front of and behind the target. Materials evaluated in this research include 6061-T6 aluminum, polyurea 1000, Styrofoam, and Sorbothane (durometer 50, shore 00). The experimental technique, calibration and checkout procedures, and results will be presented.

  7. Investigation of blast-induced traumatic brain injury

    PubMed Central

    Ludwigsen, John S.; Ford, Corey C.

    2014-01-01

    Objective Many troops deployed in Iraq and Afghanistan have sustained blast-related, closed-head injuries from being within non-lethal distance of detonated explosive devices. Little is known, however, about the mechanisms associated with blast exposure that give rise to traumatic brain injury (TBI). This study attempts to identify the precise conditions of focused stress wave energy within the brain, resulting from blast exposure, which will correlate with a threshold for persistent brain injury. Methods This study developed and validated a set of modelling tools to simulate blast loading to the human head. Using these tools, the blast-induced, early-time intracranial wave motions that lead to focal brain damage were simulated. Results The simulations predict the deposition of three distinct wave energy components, two of which can be related to injury-inducing mechanisms, namely cavitation and shear. Furthermore, the results suggest that the spatial distributions of these damaging energy components are independent of blast direction. Conclusions The predictions reported herein will simplify efforts to correlate simulation predictions with clinical measures of TBI and aid in the development of protective headwear. PMID:24766453

  8. Finite difference computation of blast diffraction

    NASA Astrophysics Data System (ADS)

    Hillier, R.; Graham, J. M. R.

    1985-07-01

    This paper discusses the use of numerical finite difference methods for predicting flow fields in which a shock or blast wave is diffracted at a sharp edge. Three different types of method are studied: Donor Cell differencing with and without Flux Corrected Transport, a Finite Volume method with an explicit artificial viscosity and Runge-Kutta time stepping, and a second order upwind method based on the solution of a Riemann wave problem at cell interfaces. In the case of weak shock waves a comparison is made with the flow field predicted by acoustic theory including flow separation. Results for stronger shocks are also presented.

  9. Study of TATP: blast characteristics and TNT equivalency of small charges

    NASA Astrophysics Data System (ADS)

    Pachman, J.; Matyáš, R.; Künzel, M.

    2014-07-01

    Blast wave parameters including incident overpressure, impulse and duration of the positive phase of the incident blast wave and its time of arrival were experimentally determined for 50 g charges of low bulk density () dry TATP (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane). The results were compared with published TNT data, and TNT equivalencies were determined, resulting in the values of 70 % based on overpressure and 55 % based on impulse of the positive phase of the blast wave. Brisance by the Hess method (lead cylinder compression) was found to be about one-third of that for TNT (at density . Detonation velocities averaged around

  10. Blast-Induced tinnitus and spontaneous firing changes in the rat dorsal cochlear nucleus.

    PubMed

    Luo, Hao; Pace, Edward; Zhang, Xueguo; Zhang, Jinsheng

    2014-11-01

    Exposure to high-pressure blast shock waves is known to cause tinnitus. Although the underlying mechanisms may involve damage to structures in the ear and/or direct brain impact, which triggers a cascade of neuroplastic changes in both auditory and nonauditory centers, it remains unclear how the induced neuroplasticity manifests neurophysiologically. This study investigates the influence of blast exposure on spontaneous firing rates (SFRs) in the dorsal cochlear nucleus (DCN) and its time course in rats with blast-induced tinnitus. Each rat was exposed to a single blast at 22 psi. Behavioral evidence of tinnitus was measured by using a gap-detection acoustic startle-reflex paradigm. SFRs were measured 1 day, 1 month, and 3 months after blast exposure. The results showed that nine rats with blast-induced tinnitus and hearing loss developed hyperactivity immediately and that the induced hyperactivity persisted in six rats with tinnitus at 1 month after blast exposure. At 3 months after blast exposure, however, the induced hyperactivity of four rats with tinnitus transitioned to hypoactivity. In addition, the 20-30-kHz, and >30-kHz regions in the DCN of rats with and without blast-induced tinnitus were more affected than other frequency regions at different recovery time points after blast exposure. These results demonstrate that the neural mechanisms underlying blast-induced tinnitus are substantially different from those underlying noise-induced tinnitus. PMID:24938852

  11. Dry ice blasting

    NASA Astrophysics Data System (ADS)

    Lonergan, Jeffrey M.

    1992-04-01

    As legal and societal pressures against the use of hazardous waste generating materials has increased, so has the motivation to find safe, effective, and permanent replacements. Dry ice blasting is a technology which uses CO2 pellets as a blasting medium. The use of CO2 for cleaning and stripping operations offers potential for significant environmental, safety, and productivity improvements over grit blasting, plastic media blasting, and chemical solvent cleaning. Because CO2 pellets break up and sublime upon impact, there is no expended media to dispose of. Unlike grit or plastic media blasting which produce large quantities of expended media, the only waste produced by CO2 blasting is the material removed. The quantity of hazardous waste produced, and thus the cost of hazardous waste disposal is significantly reduced.

  12. Blast injury of the auditory system: a review of the mechanisms and pathology.

    PubMed

    Garth, R J

    1994-11-01

    Blast injury of the auditory system is uncommon and our knowledge incomplete. This article reviews the literature to date giving an account of the interactions of blast waves with the ear, the mechanisms of injury, the pathology, the clinical features, and an outline of management principles. PMID:7829942

  13. Bond selective chemistry beyond the adiabatic approximation

    SciTech Connect

    Butler, L.J.

    1993-12-01

    One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.

  14. Blast furnace stove control

    SciTech Connect

    Muske, K.R.; Hansen, G.A.; Howse, J.W.; Cagliostro, D.J.; Chaubal, P.C.

    1998-12-31

    This paper outlines the process model and model-based control techniques implemented on the hot blast stoves for the No. 7 Blast Furnace at the Inland Steel facility in East Chicago, Indiana. A detailed heat transfer model of the stoves is developed. It is then used as part of a predictive control scheme to determine the minimum amount of fuel necessary to achieve the blast air requirements. The controller also considers maximum and minimum temperature constraints within the stove.

  15. Shortcut to adiabaticity in spinor condensates

    NASA Astrophysics Data System (ADS)

    Sala, Arnau; Núñez, David López; Martorell, Joan; De Sarlo, Luigi; Zibold, Tilman; Gerbier, Fabrice; Polls, Artur; Juliá-Díaz, Bruno

    2016-10-01

    We devise a method to shortcut the adiabatic evolution of a spin-1 Bose gas with an external magnetic field as the control parameter. An initial many-body state with almost all bosons populating the Zeeman sublevel m =0 is evolved to a final state very close to a macroscopic spin-singlet condensate, a fragmented state with three macroscopically occupied Zeeman states. The shortcut protocol, obtained by an approximate mapping to a harmonic oscillator Hamiltonian, is compared to linear and exponential variations of the control parameter. We find a dramatic speedup of the dynamics when using the shortcut protocol.

  16. On adiabatic perturbations in the ekpyrotic scenario

    SciTech Connect

    Linde, A.; Mukhanov, V.; Vikman, A. E-mail: Viatcheslav.Mukhanov@physik.uni-muenchen.de

    2010-02-01

    In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.

  17. Generalized Ramsey numbers through adiabatic quantum optimization

    NASA Astrophysics Data System (ADS)

    Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank

    2016-09-01

    Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.

  18. Cavity-state preparation using adiabatic transfer

    NASA Astrophysics Data System (ADS)

    Larson, Jonas; Andersson, Erika

    2005-05-01

    We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another and also to prepare nontrivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an Einstein-Podolsky-Rosen state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrödinger cat states. The theoretical considerations are supported by numerical simulations.

  19. Local entanglement generation in the adiabatic regime

    SciTech Connect

    Cliche, M.; Veitia, Andrzej

    2010-09-15

    We study entanglement generation in a pair of qubits interacting with an initially correlated system. Using time-independent perturbation theory and the adiabatic theorem, we show conditions under which the qubits become entangled as the joint system evolves into the ground state of the interacting theory. We then apply these results to the case of qubits interacting with a scalar quantum field. We study three different variations of this setup; a quantum field subject to Dirichlet boundary conditions, a quantum field interacting with a classical potential, and a quantum field that starts in a thermal state.

  20. An adiabatic demagnetization refrigerator for infrared bolometers

    NASA Technical Reports Server (NTRS)

    Britt, R. D.; Richards, P. L.

    1981-01-01

    Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.