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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. 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.

  8. 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.

  9. Adiabatic effects of electrons and ions on electro-acoustic solitary waves in an adiabatic dusty plasma

    NASA Astrophysics Data System (ADS)

    Tanjia, Fatema; Mamun, A. A.

    2009-02-01

    A dusty plasma consisting of negatively charged cold dust, adiabatic hot ions, and inertia-less adiabatic hot electrons has been considered. The adiabatic effects of electrons and ions on the basic properties of electro-acoustic solitary waves associated with different types of electro-acoustic (viz. ion-acoustic (IA), dust ion-acoustic (DIA), and dust acoustic (DA)) waves are thoroughly investigated by the reductive perturbation method. It is found that the basic properties of the IA, DIA, and DA waves are significantly modified by the adiabatic effects of ions and inertia-less electrons. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  10. 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.

  11. 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.

  12. Baryon Loaded Relativistic Blast Waves in Supernovae

    NASA Astrophysics Data System (ADS)

    Chakraborti, Sayan; Ray, Alak

    2011-03-01

    We provide a new analytic blast wave solution which generalizes the Blandford-McKee solution to arbitrary ejecta masses and Lorentz factors. Until recently relativistic supernovae have been discovered only through their association with long-duration gamma-ray bursts (GRBs). The blast waves of such explosions are well described by the Blandford-McKee (in the ultra-relativistic regime) and Sedov-Taylor (in the non-relativistic regime) solutions during their afterglows, as the ejecta mass is negligible in comparison to the swept-up mass. The recent discovery of the relativistic supernova SN 2009bb, without a detected GRB, opens up the possibility of highly baryon loaded, mildly relativistic outflows which remains in nearly free-expansion phase during the radio afterglow. In this work, we consider a massive, relativistic shell, launched by a Central Engine Driven EXplosion (CEDEX), decelerating adiabatically due to its collision with the pre-explosion circumstellar wind profile of the progenitor. We compute the synchrotron emission from relativistic electrons in the shock amplified magnetic field. This models the radio emission from the circumstellar interaction of a CEDEX. We show that this model explains the observed radio evolution of the prototypical SN 2009bb and demonstrate that SN 2009bb had a highly baryon loaded, mildly relativistic outflow. We discuss the effect of baryon loading on the dynamics and observational manifestations of a CEDEX. In particular, our predicted angular size of SN 2009bb is consistent with very long baseline interferometric (VLBI) upper limits on day 85, but is presently resolvable on VLBI angular scales, since the relativistic ejecta is still in the nearly free-expansion phase.

  13. Adiabatic modulation of cnoidal wave by Kuznetsov - Ma soliton

    NASA Astrophysics Data System (ADS)

    Makarov, V. A.; Petnikova, V. M.; Shuvalov, V. V.

    2016-08-01

    The problem of nonlinear interaction of a cnoidal wave (a “fast” component of vector light field) with localized in time and periodic in space control signal in the form of Kuznetsov-Ma soliton (a "slow" component of the same field) is analytically solved in the adiabatic approximation. The conditions which must be fulfilled for stable propagation of the obtained solution with amplitude and frequency modulation are determined.

  14. Blast Wave Experiments at Z

    DTIC Science & Technology

    2007-06-01

    radiation flows upward, it passes though a 1.7-mm high, tapered, 25-μm thick gold wall cone that is filled 20 ± 3 mg/cm3 silica aerogel (SiO2). Above...this cone is a 20 ± 3 mg/cm3 silica aerogel filled, 1-mm high, 2.4-mm inner diameter, 25-μm thick gold wall cylinder. On the cylinder rests a 4-mm...diameter gold platform that supports a higher density (40-60 mg/cm3) silica aerogel . This aerogel is the region where the blast wave forms after

  15. 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

  16. Shortcut to adiabatic control of soliton matter waves by tunable interaction

    PubMed Central

    Li, Jing; Sun, Kun; Chen, Xi

    2016-01-01

    We propose a method for shortcut to adiabatic control of soliton matter waves in harmonic traps. The tunable interaction controlled by Feshbach resonance is inversely designed to achieve fast and high-fidelity compression of soliton matter waves as compared to the conventional adiabatic compression. These results pave the way to control the nonlinear dynamics for matter waves and optical solitons by using shortcuts to adiabaticity. PMID:28009007

  17. 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.

  18. 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.

  19. 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.

  20. Blast waves from cylindrical charges

    NASA Astrophysics Data System (ADS)

    Knock, C.; Davies, N.

    2013-07-01

    Comparisons of explosives are often carried out using TNT equivalency which is based on data for spherical charges, despite the fact that many explosive charges are not spherical in shape, but cylindrical. Previous work has shown that it is possible to predict the over pressure and impulse from the curved surface of cylindrical charges using simple empirical formulae for the case when the length-to-diameter ( L/ D) ratio is greater or equal to 2/1. In this paper, by examining data for all length-to-diameter ratios, it is shown that it is possible to predict the peak over pressure, P, for any length-to-diameter ratio from the curved side of a bare cylindrical charge of explosive using the equation P=K_PM(L/D)^{1/3}/R^3, where M is the mass of explosive, R the distance from the charge and K_P is an explosive-dependent constant. Further out where the cylindrical blast wave `heals' into a spherical one, the more complex equation P=C_1(Z^' ' })^{-3}+C_2(Z^' ' })^{-2}+C_3(Z^' ' })^{-1} gives a better fit to experimental data, where Z^' ' } = M^{1/3}(L/D)^{1/9}/D and C_1, C_2 and C_3 are explosive-dependent constants. The impulse is found to be independent of the L/ D ratio.

  1. 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.

  2. Dusty Blast Wave in Cassiopeia A

    NASA Astrophysics Data System (ADS)

    Borkowski, Kazimierz J.; Williams, B. J.; Reynolds, S. P.

    2006-09-01

    The Spitzer Space Telescope has revealed infrared emission from dust in the blast wave of the youngest Galactic supernova remnant Cas A. This fast 6000 km/s blast wave is sweeping up circumstellar material expelled by the Cas A supernova progenitor prior to its explosion, presumably in a slow and dense wind in its final red supergiant (RSG) evolutionary stage. Dust in the blast wave was detected through imaging at 24 and 70 microns with the Multiband Imaging Photometer for Spitzer (MIPS). We use a collisionally-heated dust model to interpret these MIPS observations. In this model, silicate grains are heated and destroyed in collisions with fast thermal electrons and ions in the blast wave. We consider a wide range in grain radii in the preshock gas, from 0.001 to 0.25 microns, with grains distributed as a power law in radius with an index of -3.5. We measured MIPS fluxes and their ratios in several regions in the north and south, and derived dust masses and plasma densities by comparing them with the dust models. The dust masses are 0.0001 solar masses in the south and several times higher in the north, while estimated electron densities range from 3 per cc in the south up to 20 per cc in the north. In order to estimate dust/gas mass ratios, we also examined Chandra X-ray spectra of the blast wave. We modeled them successfully with a combination of a thermal plane shock and a nonthermal synchrotron "srcut" model. The estimated gas masses are about 1000 times larger than dust masses. Our inferred dust content implies large depletions of several refractory elements onto dust grains in the stellar outflow of the Cas A RSG progenitor. We discuss how such depletions affect X-ray spectra produced within the dusty blast wave of Cas A.

  3. 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.

  4. 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.

  5. 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.

  6. Gamma-ray burst afterglows from transrelativistic blast wave simulations

    NASA Astrophysics Data System (ADS)

    van Eerten, H. J.; Leventis, K.; Meliani, Z.; Wijers, R. A. M. J.; Keppens, R.

    2010-03-01

    We present a study of the intermediate regime between ultrarelativistic and non-relativistic flow for gamma-ray burst afterglows. The hydrodynamics of spherically symmetric blast waves is numerically calculated using the AMRVAC adaptive mesh refinement code. Spectra and light curves are calculated using a separate radiation code that, for the first time, links a parametrization of the microphysics of shock acceleration, synchrotron self-absorption and electron cooling to a high-performance hydrodynamic simulation. For the dynamics, we find that the transition to the non-relativistic regime generally occurs later than expected, the Sedov-Taylor solution overpredicts the late-time blast wave radius and the analytical formula for the blast wave velocity from Huang, Dai & Lu overpredicts the late-time velocity by a factor of 4/3. Also, we find that the lab frame density directly behind the shock front divided by the fluid Lorentz factor squared remains very close to four times the unshocked density, while the effective adiabatic index of the shock changes from relativistic to non-relativistic. For the radiation, we find that the flux may differ up to an order of magnitude depending on the equation of state that is used for the fluid and that the counterjet leads to a clear rebrightening at late times for hard-edged jets. Simulating GRB 030329 using predictions for its physical parameters from the literature leads to spectra and light curves that may differ significantly from the actual data, emphasizing the need for very accurate modelling. Predicted light curves at low radio frequencies for a hard-edged jet model of GRB 030329 with opening angle 22° show typically two distinct peaks, due to the combined effect of jet break, non-relativistic break and counterjet. Spatially resolved afterglow images show a ring-like structure.

  7. ENTROPY-VORTEX WAVES IN NON-ADIABATIC FLOWS

    SciTech Connect

    Ibáñez S, Miguel H.

    2016-02-20

    The Ertel theorem on the vorticity along the flow of adiabatic fluids is generalized for non-adiabatic flows. Several limiting cases are analyzed and the results are applied to flows behind different hydrodynamics fronts, particularly to thermal fronts (heat and cooling fronts). An important conclusion of the present analysis is that vorticity is inherent in the condensation’s (or hot spots) formation by thermal instabilities in plasma flows. Implications for several astrophysical plasmas are outlined.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Resonant modal interactions and adiabatic invariance for a nonlinear wave equation in a variable domain

    NASA Astrophysics Data System (ADS)

    Kevorkian, J.; Li, H. K.

    1984-08-01

    The technique of isolating and order reducing transformations for computing adiabatic invariants in finite-degree-of-freedom Hamiltonian sytems is extended to the case of the non-Hamiltonian modal representation of a wave equation with weak nonlinearities in a slowly varying domain. The mechanism of resonant interactions for two or more normal modes whereby the associated actions change rapidly in a short period is exhibited. In the Hamiltonian problem there are a number of global adiabatic invariants associated with each resonance. Conditions for which similar adiabatic invariants can be found for the non-Hamiltonian case are derived. The results are then verified by extensive numerical computations.

  13. Arbitrary amplitude electro-acoustic solitary waves in an adiabatic dusty plasma

    NASA Astrophysics Data System (ADS)

    Tanjia, Fatema; Mamun, A. A.

    2008-12-01

    The properties of different types of electro-acoustic (namely ion-acoustic (IA), dust ion-acoustic (DIA), and dust-acoustic (DA)) solitary waves (SWs) in an adiabatic dusty plasma (containing negatively charged cold dust, adiabatic hot ions and inertia-less adiabatic hot electrons) are investigated by the pseudo-potential approach. The combined effects of the adiabatic electrons and ions, and negatively charged dust on the basic properties (critical Mach number, amplitude and width) of the arbitrary amplitude electro-acoustic SWs are systematically and explicitly examined. It is found that the combined effects of the adiabatic electrons and ions, and negatively charged dust significantly modify the basic properties (critical Mach number, amplitude and width) of the SWs. It is also found that due to the effect of the adiabaticity of electrons, the negative DIA SWs (which are found to exist in a dusty plasma containing isothermal electrons, cold ions and negatively charged static dust) disappear, i.e. due to the effect of adiabatic electrons, one cannot have negative DIA SWs for any possible set of dusty plasma parameters.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Afterglow emission in gamma-ray bursts - I. Pair-enriched ambient medium and radiative blast waves

    NASA Astrophysics Data System (ADS)

    Nava, L.; Sironi, L.; Ghisellini, G.; Celotti, A.; Ghirlanda, G.

    2013-08-01

    Forward shocks caused by the interaction between a relativistic blast wave and the circumburst medium are thought to be responsible for the afterglow emission in gamma-ray bursts (GRBs). We consider the hydrodynamics of a spherical relativistic blast wave expanding into the surrounding medium and we generalize the standard theory in order to account for several effects that are generally ignored. In particular, we consider the role of adiabatic and radiative losses in the hydrodynamical evolution of the shock, under the assumption that the cooling losses are fast. Our model can describe adiabatic, fully radiative and semiradiative blast waves, and can describe the effects of a time-varying radiative efficiency. The equations we present are valid for arbitrary density profiles, and also for a circumburst medium enriched with electron-positron pairs. The presence of pairs enhances the fraction of shock energy gained by the leptons, thus increasing the importance of radiative losses. Our model allows us to study whether the high-energy (>0.1 GeV) emission in GRBs may originate from afterglow radiation. In particular, it is suitable to test whether the fast decay of the high-energy light curve observed in several Fermi Large Area Telescope GRBs can be ascribed to an initial radiative phase, followed by the standard adiabatic evolution.

  19. 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.

  20. 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.

  1. Dust-acoustic solitary waves in a four-component adiabatic magnetized dusty plasma

    SciTech Connect

    Akhter, T. Mannan, A.; Mamun, A. A.

    2013-07-15

    Theoretical investigation has been made on obliquely propagating dust-acoustic (DA) solitary waves (SWs) in a magnetized dusty plasma which consists of non-inertial adiabatic electron and ion fluids, and inertial negatively as well as positively charged adiabatic dust fluids. The reductive perturbation method has been employed to derive the Korteweg-de Vries equation which admits a solitary wave solution for small but finite amplitude limit. It has been shown that the basic features (speed, height, thickness, etc.) of such DA solitary structures are significantly modified by adiabaticity of plasma fluids, opposite polarity dust components, and the obliqueness of external magnetic field. The SWs have been changed from compressive to rarefactive depending on the value of {mu} (a parameter determining the number of positive dust present in this plasma model). The present investigation can be of relevance to the electrostatic solitary structures observed in various dusty plasma environments (viz. cometary tails, upper mesosphere, Jupiter's magnetosphere, etc.)

  2. Evolution of blast wave profiles in simulated air blasts: experiment and computational modeling

    NASA Astrophysics Data System (ADS)

    Chandra, N.; Ganpule, S.; Kleinschmit, N. N.; Feng, R.; Holmberg, A. D.; Sundaramurthy, A.; Selvan, V.; Alai, A.

    2012-09-01

    Shock tubes have been extensively used in the study of blast traumatic brain injury due to increased incidence of blast-induced neurotrauma in Iraq and Afghanistan conflicts. One of the important aspects in these studies is how to best replicate the field conditions in the laboratory which relies on reproducing blast wave profiles. Evolution of the blast wave profiles along the length of the compression-driven air shock tube is studied using experiments and numerical simulations with emphasis on the shape and magnitude of pressure time profiles. In order to measure dynamic pressures of the blast, a series of sensors are mounted on a cylindrical specimen normal to the flow direction. Our results indicate that the blast wave loading is significantly different for locations inside and outside of the shock tube. Pressure profiles inside the shock tube follow the Friedlander waveform fairly well. Upon approaching exit of the shock tube, an expansion wave released from the shock tube edges significantly degrades the pressure profiles. For tests outside the shock tube, peak pressure and total impulse reduce drastically as we move away from the exit and majority of loading is in the form of subsonic jet wind. In addition, the planarity of the blast wave degrades as blast wave evolves three dimensionally. Numerical results visually and quantitatively confirm the presence of vortices, jet wind and three-dimensional expansion of the planar blast wave near the exit. Pressure profiles at 90° orientation show flow separation. When cylinder is placed inside, this flow separation is not sustained, but when placed outside the shock tube this flow separation is sustained which causes tensile loading on the sides of the cylinder. Friedlander waves formed due to field explosives in the intermediate-to far-field ranges are replicated in a narrow test region located deep inside the shock tube.

  3. Piecewise Adiabatic Population Transfer in a Molecule via a Wave Packet

    SciTech Connect

    Shapiro, Evgeny A.; Peer, Avi; Ye Jun; Shapiro, Moshe

    2008-07-11

    We propose a class of schemes for robust population transfer between quantum states that utilize trains of coherent pulses, thus forming a generalized adiabatic passage via a wave packet. We study piecewise stimulated Raman adiabatic passage with pulse-to-pulse amplitude variation, and piecewise chirped Raman passage with pulse-to-pulse phase variation, implemented with an optical frequency comb. In the context of production of ultracold ground-state molecules, we show that with almost no knowledge of the excited potential, robust high-efficiency transfer is possible.

  4. 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

  5. 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.

  6. 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.

  7. Dust ion-acoustic shock waves in an adiabatic dusty plasma

    SciTech Connect

    Rahman, Armina; Sayed, Fatema; Mamun, A. A.

    2007-03-15

    The properties of dust ion-acoustic shock waves in an unmagnetized dusty plasma, whose constituents are adiabatic ion fluid, Boltzmann electrons, and static dust, are investigated by employing the reductive perturbation method. The Burgers equation is derived and its stationary analytical solution is numerically analyzed. It has been found that both the amplitude and the width decrease with the increase of the ion-fluid temperature. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

  8. 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.

  9. Nonlinear heavy-ion-acoustic waves in an adiabatic collisionless bi-ion plasma

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    The basic properties of heavy-ion-acoustic (HIA) waves have been investigated in a collisionless plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The Kortewg-de Vries and Burgers equations are derived in nonplanar (cylindrical and spherical) geometry by employing the standard reductive perturbation method for studying the basic features (viz. amplitude, phase speed, etc.) of HIA solitary and shock waves, which are associated with either positive or negative potential. It is found that the effects of nonplanar geometry, adiabaticity of positively charged inertial heavy ions, the presence of nonthermal (Cairns distributed) electrons, and number densities of the plasma components significantly modify the basic features of nonplanar HIA waves. It has been observed that the properties of solitary and shock waves associated with HIA waves in a nonplanar geometry differ from those in a planar geometry. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments.

  10. 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.

  11. 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.

  12. 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.

  13. Adiabatic effects on nonlinear dust-acoustic solitary and shock waves in a strongly coupled dusty plasma

    SciTech Connect

    Rahman, M. S.; Mamun, A. A.

    2011-12-15

    A theoretical investigation has been performed on a strongly coupled dusty plasma containing strongly correlated negatively charged dust grains and weakly correlated adiabatic electrons and ions. The adiabatic effects on the dust-acoustic (DA) solitary and shock waves propagating in such a strongly coupled dusty plasma are taken into account. The DA solitary and shock waves are found to exist with negative potential only. It has been shown that the strong correlation among the charged dust grains is a source of dissipation and is responsible for the formation of the DA shock waves. It has also been found that the effects of adiabaticity significantly modify the basic features (e.g., amplitude, width, speed, etc.) of the DA solitary and shock waves. It has been suggested that a laboratory experiment be performed to test the theory presented in this work.

  14. 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.

  15. On the stability of obliquely propagating dust ion-acoustic solitary waves in hot adiabatic magnetized dusty plasmas

    NASA Astrophysics Data System (ADS)

    Shalaby, M.; EL-Labany, S. K.; EL-Shamy, E. F.; El-Taibany, W. F.; Khaled, M. A.

    2009-12-01

    Obliquely propagating dust ion acoustic solitary waves (DIASWs) are investigated in hot adiabatic magnetized dusty plasmas consisting of hot adiabatic inertial ions, hot adiabatic inertialess electrons, and negatively/positively charged static dust grains. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The effects of the concentration of negatively/positively charged dust particles and ion-neutral collision on the basic characteristics of DIASWs are studied. The three-dimensional stability of these waves is examined by the use of small-k (long wavelength plane wave) perturbation expansion technique. It is shown that the instability criterion and their growth rate depend on external magnetic field, obliqueness, the concentration of charged dust grains, ion-neutral, and ion-dust collisions.

  16. Numerical modeling and characterization of blast waves for application in blast-induced mild traumatic brain injury research

    NASA Astrophysics Data System (ADS)

    Phillips, Michael G.

    Human exposure to blast waves, including blast-induced traumatic brain injury, is a developing field in medical research. Experiments with explosives have many disadvantages including safety, cost, and required area for trials. Shock tubes provide an alternative method to produce free field blast wave profiles. A compressed nitrogen shock tube experiment instrumented with static and reflective pressure taps is modeled using a numerical simulation. The geometry of the numerical model is simplified and blast wave characteristics are derived based upon static and pressure profiles. The pressure profiles are analyzed along the shock tube centerline and radially away from the tube axis. The blast wave parameters found from the pressure profiles provide guidelines for spatial location of a specimen. The location could be based on multiple parameters and provides a distribution of anticipated pressure profiles experience by the specimen.

  17. High-speed photography of microscale blast wave phenomena

    NASA Astrophysics Data System (ADS)

    Dewey, John M.; Kleine, Harald

    2005-03-01

    High-speed photography has been a primary tool for the study of blast wave phenomena, dating from the work of Toepler, even before the invention of the camera! High-speed photography was used extensively for the study of blast waves produced by nuclear explosions for which, because of the large scale, cameras running at a few hundred frames per second were adequate to obtain sharp images of the supersonic shock fronts. For the study of the blast waves produced by smaller explosive sources, ever-increasing framing rates were required. As a rough guide, for every three orders of magnitude decrease in charge size a ten-fold increase of framing rate was needed. This severely limited the use of photography for the study of blast waves from laboratory-scale charges. There are many techniques for taking single photographs of explosive phenomena, but the strongly time-dependent development of a blast wave, requires the ability to record a high-speed sequence of photographs of a single event. At ICHSPP25, Kondo et al of Shimadzu Corporation demonstrated a 1 M fps video camera that provides a sequence of up to 100 high-resolution frames. This was subsequently used at the Shock Wave Research Center of Tohoku University to record the blast waves generated by an extensive series of silver azide charges ranging in size from 10 to 0.5mg. The resulting images were measured to provide radius-time histories of the primary and secondary shocks. These were analyzed with techniques similar to those used for the study of explosions from charges with masses ranging from 500 kg to 5 kt. The analyses showed the cube-root scaling laws to be valid for the very small charges, and provided a detailed record of the peak hydrostatic pressure as a function of radius for a unit charge of silver azide, over a wide range of scaled distances. The pressure-radius variation was compared to that from a unit charge of TNT and this permitted a detailed determination of the TNT equivalence of silver azide

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Characteristics of nonlinear dust acoustic waves in a Lorentzian dusty plasma with effect of adiabatic and nonadiabatic grain charge fluctuation

    NASA Astrophysics Data System (ADS)

    Denra, Raicharan; Paul, Samit; Sarkar, Susmita

    2016-12-01

    In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.

  3. 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.

  4. Growth of interfacial perturbations driven by blast waves

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, Marc; Johnsen, Eric; Shvarts, Dov; Drake, R. Paul

    2016-10-01

    Hydrodynamic instabilities play important roles in a variety of high-energy-density physics flows, including problems in astrophysics and inertial confinement fusion. While classical Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) unstable interfacial flows are relatively well understood, less is known about interactions of blast waves with interfaces. Using a new 2D high-order Discontinuous Galerkin multifluid hydro code, we simulate the interaction of a blast, modeled as a shock followed by a finite-length rarefaction, with a single-mode, perturbed interface separating heavy and light fluids. This model allows us to control, independently, the shock strength, rarefaction strength and length. Starting the blast in the heavy material gives rise to an RT-unstable configuration (driven by the rarefaction). Our findings indicate that the time-evolution of the perturbation growth can be described as a succession of three phases corresponding to different mechanisms (linear RM, combined decompression and RT with time-varying Atwood number and acceleration, and circulation-driven), which we will explain in detail and relate to the blast properties. Supported in part by LLNL under subcontract B614207 to DE-AC52-07NA27344.

  5. 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.

  6. Numerical simulations of blast wave characteristics with a two-dimensional axisymmetric room model

    NASA Astrophysics Data System (ADS)

    Sugiyama, Y.; Homae, T.; Wakabayashi, K.; Matsumura, T.; Nakayama, Y.

    2017-01-01

    This paper numerically visualizes explosion phenomena in order to discuss blast wave characteristics with a two-dimensional axisymmetric room model. After the shock wave exits via an opening, the blast wave propagates into open space. In the present study, a parametric study was conducted to determine the blast wave characteristics from the room exit by changing the room shape and the mass of the high explosive. Our results show that the blast wave characteristics can be correctly estimated using a scaling factor proposed in the present paper that includes the above parameters. We conducted normalization of the peak overpressure curve using the shock overpressure at the exit and the length scale of the room volume. In the case where the scaling factor has the same value, the normalized peak overpressure curve does not depend on the calculation conditions, and the scaling factor describes the blast wave characteristics emerging from the current room model.

  7. Blast wave attenuation by lightly destructable granular materials

    NASA Astrophysics Data System (ADS)

    Golub, V. V.; Lu, F. K.; Medin, S. A.; Mirova, O. A.; Parshikov, A. N.; Petukhov, V. A.; Volodin, V. V.

    Terrorist bombings are a dismal reality nowadays. One of the most effective ways for protection against blast overpressure is the use of lightly compacted materials such as sand [1] and aqueous foam [2] as a protective envelope or barrier. According to [1], shock wave attenuation in a mine tunnel (one-dimensional case) behind a destroyed object is given by q_e ≈ q {1}/{1 + 4(S/q)^{1/6} bρ _{mat} /L^{1/3} }where qe — effective charge, S — exposed area of the obstacle, q — TNT equivalent (grams), L — distance between charge and obstacle, b — obstacle thickness and ρ mat — material density. This empirical equation is applicable only in a one-dimensional case but not for a less confined environment. Another way of protecting a structure against blast is to coat the surface with a sacrificial layer. In [3] full-scale experiments were carried out to investigate the behaviour of a covering of aluminum foam under the effect of a blast wave.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. The distinctive feature of long time adiabatic modulation in the context of cnoidal wave and Akhmediev breaser interaction

    NASA Astrophysics Data System (ADS)

    Makarov, V. A.; Petnikova, V. M.

    2017-02-01

    For a nonintegrable system of two coupled nonlinear Schrödinger equations the adiabatic approximation is extended for long time interaction. The method enables analytical description of the modulation of a cnoidal wave by Akhmediev breather in an isotropic nonlinear gyrotropic medium with Kerr nonlinearity and second-order group-velocity dispersion. The conditions which must be fulfilled for stable propagation of the obtained solution with amplitude and frequency modulation are determined.

  15. Numerical Investigation of Aluminum Burning Behind Blast Waves

    DTIC Science & Technology

    2010-10-01

    Hendrson[8]. 3/1)/6( ps Nd πφ= (4) )/(6 2dNuh gs λφ= (5) where Nu is a Nusselt number calculated from equations derived by Carlson and Hoglund[9...failing to comply with a collection of information if it does not display a currently valid OMB control number . 1. REPORT DATE OCT 2010 2. REPORT TYPE...N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Numerical Investigation Ofaluminum Burning Behind Blast Waves 5a. CONTRACT NUMBER 5b. GRANT

  16. 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.

  17. 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.

  18. Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves with a Long-lived Reverse Shock

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing; Hascoët, Romain; Daigne, Frédéric; Mochkovitch, Robert; Park, Il H.

    2012-12-01

    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.

  19. 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.

  20. Generation of planar blast waves using carbon nanotubes-poly-dimethylsiloxane optoacoustic transducer

    NASA Astrophysics Data System (ADS)

    Moon, C.; Fan, X.; Ha, K.; Kim, D.

    2017-01-01

    We have generated planar blast waves over the large area using carbon nanotubes(CNT)-poly-dimethylsiloxane(PDMS) optoacoustic transducer. Pulse laser is absorbed by CNT and converted to heat, and the heat is transferred to PDMS inducing its thermal expansion and blast wave generation. To theoretically describe the planar blast wave generation, we build one-dimensional simulation model and find analytical solutions for temperature and pressure distributions. The analytical solution validated by the experimental data sheds light on how to improve the performance of the new transducer. Resonance of acoustic waves inside the transducer is also discussed. The new optoacoustic transducer optimized based on the fundamental understandings will be useful in generating high quality blast waves for research and industrial applications.

  1. 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.

  2. 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.

  3. The Sedov Blast Wave as a Radial Piston Verification Test

    DOE PAGES

    Pederson, Clark; Brown, Bart; Morgan, Nathaniel

    2016-06-22

    The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented onmore » two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.« less

  4. The Sedov Blast Wave as a Radial Piston Verification Test

    SciTech Connect

    Pederson, Clark; Brown, Bart; Morgan, Nathaniel

    2016-06-22

    The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented on two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.

  5. Quantifying Momentum Transfer Due to Blast Waves from Oxy-Acetylene Driven Shock Tubes

    DTIC Science & Technology

    2012-05-30

    Transfer Due to Blast Waves from Oxy - Acetylene Driven Shock Tubes 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...and the response of materiel to blast loading. Recently, laboratory-scale shock tubes driven by oxy - acetylene were described. It was estimated that...later. In each case, most of the momentum transfer was due to the shock wave itself. The results support previous estimates that the oxy - acetylene

  6. A Nonsimilar Solution for Blast Waves Driven by an Asymptotic Piston Expansion.

    DTIC Science & Technology

    1983-06-01

    piston (contact surface) expands . Such a technique is presented here; it is nonsimilar and assumes an asymptotic energy input to the blast wave. The...is extended here to describe the more realistic case of blast waves driven by an asymptotic piston -like motion of an expanding inner gas. For the same...ASYMPTOTIC PISTON EXPA .(U) ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND ABERDEEN PROVI. M L BUNDY. JUN 83 UNCLaSSIFED AR -TR-82497 SBI-AD-F388 272

  7. 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.

  8. Coupled wave-packets for non-adiabatic molecular dynamics: a generalization of Gaussian wave-packet dynamics to multiple potential energy surfaces

    SciTech Connect

    White, Alexander James; Tretiak, Sergei; Mozyrsky, Dima V.

    2016-04-25

    Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc surface hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Heller's thawed Gaussian wave-packet dynamics that includes coupling between potential energy surfaces. By studying several standard test problems we demonstrate that the accuracy of the method can be systematically improved while maintaining high efficiency. The method is suitable for investigating the role of quantum coherence in the non-adiabatic dynamics of many-atom molecules.

  9. Coupled wave-packets for non-adiabatic molecular dynamics: a generalization of Gaussian wave-packet dynamics to multiple potential energy surfaces

    DOE PAGES

    White, Alexander James; Tretiak, Sergei; Mozyrsky, Dima V.

    2016-04-25

    Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc surface hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Heller's thawed Gaussian wave-packet dynamics that includes coupling between potential energy surfaces. By studying several standard test problems we demonstrate that the accuracy of the method can be systematically improved while maintaining high efficiency. The method is suitablemore » for investigating the role of quantum coherence in the non-adiabatic dynamics of many-atom molecules.« less

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Feasibility Study of Shock Wave Modification in the BRL 2.44 m Blast Simulator

    DTIC Science & Technology

    1984-03-01

    piezoelectric transducers were used in the shock tube test nonitor the blast wave shape and interaction with the rarefaction section 3 to monil wave...UT 84022 87 DISTRIBUTION LIST No. of Copies Organization Commander US Army Foreign Science and Technology Center ATTN: RSCH & Data Branch

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

    SciTech Connect

    Artemyev, A. V.; Zelenyi, L. M.; Vainchtein, D. L.

    2010-12-15

    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.

  17. Relationship between Orientation to a Blast and Pressure Wave Propagation Inside the Rat Brian

    DTIC Science & Technology

    2011-01-01

    generated during an explosion may result in brain damage anll related neuro- logical impairments. Several mechanisms by which the primary blast wave can...CSF). to the central nervous system. To address a basic question related to the mechanisms of blast brain injury. pressure was measured inside the...can damage the bra in have been pro- posed, includi ng: ( 1) mechanical displacement of brain resulting in contusions and hemorrhages and direct

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Dynamics and stability of relativistic gamma-ray-bursts blast waves

    NASA Astrophysics Data System (ADS)

    Meliani, Z.; Keppens, R.

    2010-09-01

    Aims: In gamma-ray-bursts (GRBs), ultra-relativistic blast waves are ejected into the circumburst medium. We analyse in unprecedented detail the deceleration of a self-similar Blandford-McKee blast wave from a Lorentz factor 25 to the nonrelativistic Sedov phase. Our goal is to determine the stability properties of its frontal shock. Methods: We carried out a grid-adaptive relativistic 2D hydro-simulation at extreme resolving power, following the GRB jet during the entire afterglow phase. We investigate the effect of the finite initial jet opening angle on the deceleration of the blast wave, and identify the growth of various instabilities throughout the coasting shock front. Results: We find that during the relativistic phase, the blast wave is subject to pressure-ram pressure instabilities that ripple and fragment the frontal shock. These instabilities manifest themselves in the ultra-relativistic phase alone, remain in full agreement with causality arguments, and decay slowly to finally disappear in the near-Newtonian phase as the shell Lorentz factor drops below 3. From then on, the compression rate decreases to levels predicted to be stable by a linear analysis of the Sedov phase. Our simulations confirm previous findings that the shell also spreads laterally because a rarefaction wave slowly propagates to the jet axis, inducing a clear shell deformation from its initial spherical shape. The blast front becomes meridionally stratified, with decreasing speed from axis to jet edge. In the wings of the jetted flow, Kelvin-Helmholtz instabilities occur, which are of negligible importance from the energetic viewpoint. Conclusions: Relativistic blast waves are subject to hydrodynamical instabilities that can significantly affect their deceleration properties. Future work will quantify their effect on the afterglow light curves.

  7. 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.

  8. 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.

  9. A viscous blast-wave model for heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Jaiswal, Amaresh; Koch, Volker

    2017-01-01

    We present a generalization of the blast-wave model by incorporating viscous effects in the fluid velocity profile as well as in the Cooper-Frye freeze-out. We apply this model to study the identified particles spectra and anisotropic flow at the Large Hadron Collider (LHC). We show that this improved viscous blast-wave model leads to good description of the transverse momentum distribution of particle multiplicities and elliptic as well as triangular flow. Within this model, we estimate the shear viscosity to entropy density ratio η/s ≃ 0.24 at the LHC.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  11. 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.

  12. Modeling Blast Wave Propagation in a Generic Facility

    DTIC Science & Technology

    2010-10-01

    depends on the extent of failure of the interior walls surrounding the blast. As the walls fail, the propagating airblast convects the wall debris to...resulting from an internal detonation is a coupled fluid and structural dynamics problem that depends on the extent of failure of the interior walls...FEFLO and CHEETAH , and the structural response to the blast loading using the coupled CFD and CSD methodology, where the structural domain is embedded

  13. A New Method for Very Fast Simulation of Blast Wave Propagation in Complex Built Environments

    DTIC Science & Technology

    2010-01-01

    as AUTODYN (ANSYS, 2008)). Unfortunately, three dimensional CFD models of blast wave propagation, even when limited to a single barrier and...The work reported in this paper was completed with the support of USAF, contract FA4819- 07-D-0001. References ANSYS. (2008). “ AUTODYN 2D and 3D

  14. Adaptation of Flux-Corrected Transport Algorithms for Modelling Blast Waves.

    DTIC Science & Technology

    1982-10-12

    solving nonsay compresible flow problems. in models which treat all the physical Seffects required for blast wave simulation, truncation errrs inherent...maintained and the calculation remains one- dimensional. A nonuniform radial grid was used with extremely fine zoning near the shock front. The grid was

  15. 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.

  16. 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).

  17. Numerical investigation of the effects of shock tube geometry on the propagation of an ideal blast wave profile

    NASA Astrophysics Data System (ADS)

    Li, X. D.; Hu, Z. M.; Jiang, Z. L.

    2017-03-01

    Bio-shock tubes (BSTs) can approximately simulate the typical blast waves produced by nuclear or chemical charge explosions for use in biological damage studies. The profile of an ideal blast wave in air is characterized by the overpressure, the negative pressure, and the positive pressure duration, which are determined by the geometric configurations of BSTs. Numerical experiments are carried out using the Eulerian equations by the dispersion-controlled dissipative scheme to investigate the effect of different structural components on ideal blast waveforms. The results show that cylindrical and conical frustum driver sections with an appropriate length can produce typical blast wave profiles, but a flattened peak pressure may appear when using a tube of a longer length. Neither a double-expansion tube nor a shrinkage tube set in BSTs is practical for the production of an ideal blast waveform. In addition, negative pressure recovery will occur, exceeding the ambient pressure with an increase in pressure in the vacuum section.

  18. 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

  19. A Three-Dimensional Numerical Investigation into the Interaction of Blast Waves with Bomb Shelters

    NASA Astrophysics Data System (ADS)

    Tai, Chang-Hsien; Teng, Jyh-Tong; Lo, Shi-Wei; Liu, Chia-Wei

    This study investigates the behavior of blast wave by employing the finite volume method to solve the associated three-dimensional, time-dependent, inviscous flow Euler equations. The numerical results are shown to be in good agreement with the experimental results obtained from shock tube flow studies. The results also identify the complex phenomena of flow structures, pressure distributions, and different types of reflected waves for closed-ended and open-ended bomb shelters.

  20. 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.

  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. 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.

  3. 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.

  4. Rapid Simulation of Blast Wave Propagation in Built Environments Using Coarse-Grain Based Intelligent Modeling Methods

    DTIC Science & Technology

    2011-04-01

    experiments was performed using an artificial neural network to try to capture the nonlinearities. The radial Gaussian artificial neural network system...Modeling Blast-Wave Propagation using Artificial Neural Network Methods‖, in International Journal of Advanced Engineering Informatics, Elsevier

  5. Blast Wave Formation by Laser-Sustained Nonequilibrium Plasma in the Laser-Driven In-Tube Accelerator Operation

    SciTech Connect

    Ogino, Yousuke; Ohnishi, Naofumi; Sawada, Keisuke; Sasoh, Akihiro

    2006-05-02

    Understanding the dynamics of laser-produced plasma is essentially important for increasing available thrust force in a gas-driven laser propulsion system such as laser-driven in-tube accelerator. A computer code is developed to explore the formation of expanding nonequilibrium plasma produced by laser irradiation. Various properties of the blast wave driven by the nonequilibrium plasma are examined. It is found that the blast wave propagation is substantially affected by radiative cooling effect for lower density case.

  6. 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}.

  7. 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.

  8. Soil Liquefaction Resulting from Blast-Induced Spherical Stress Waves

    DTIC Science & Technology

    1990-01-01

    on vibration sensitive. two phase materials like loose saturated sands, there can be elastic strain in the water phase but plastic strain in the sand...similar behaviour. Liquefaction can be induced by a variety of loading menhanisms including monotonic stress changes, earthquakes, and blast vibrations ...A sandstone bedrock is estimated to lie between 8 and 9 m below the ground surface with a series of folded shale layers over the sandstone. The top

  9. Blast wave dynamics: The influence of the shape of the explosive.

    PubMed

    Artero-Guerrero, J; Pernas-Sánchez, J; Teixeira-Dias, F

    2017-06-05

    A numerical model is developed to analyse the influence of the shape of a high-explosive on the dynamics of the generated pressure wave. A Multi-Material Arbitrary Lagrangian Eulerian (MM-ALE) technique is used as the CONWEP approach is not adequate to model such situations. Validation and verification of the proposed numerical model is achieved based on experimental data obtained from the bibliography. The numerical model provides relevant information that cannot be obtained from the experimental results. The influence of the mass and shape of the high-explosive is studied and correlated to the dynamics of the generated blast wave through the analysis of peak pressures, time of arrival and impulse. Tests are done with constant mass hemispherical, cylindrical and flat-shaped Formex F4HV samples. A detailed analysis of the generated blast wave is done, along with a thorough comparison between incident and reflected waves. It is concluded that the dynamic effects of the reflected pressure pulses should always be considered in structural design, most relevantly when analysing closed structures where the number of reflections can be significant. The model is proved reliable, concluding that the frontal area of the high-explosive is a determinant driving parameter for the impulse generated by the blast.

  10. 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.

  11. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Elastomeric Polymer-by-Design for Blast-Induced Shock-Wave Management

    DTIC Science & Technology

    2015-06-01

    ORGANIZATION . REPORT DATE (DD-MM-YYYY) 01-06-2015 2. REPORT TYPE Final Technical Performance Report 3. DATES COVERED (From - To) September 1...2009 - November 30, 2014 4. TITLE AND SUBTITLE Elastomerie Polymer -by-Design for Blast-Induced Shock-Wave Management [ONR BRC Program] 5a. CONTRACT...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Regents of UC San Diego Department of Mechanieal and Aerospace

  19. Water Temperature and Concentration Measurements Within the Expanding Blast Wave of a High Explosive

    DTIC Science & Technology

    2011-03-15

    housing was made of 1018 steel , and the gauge roof was extended to shield the opto- mechanical components from the primary blast wave. The input fiber...regions of each image indicate the steel frame and support crossbars of the gauge. This set of images provides a sense of the speed with which the shock was...University Press) [3] Peuker J M, Lynch P, Krier H and Glumac N 2009 Optical depth measurements of fireballs from aluminized high explosives Opt

  20. The Effects of Reverberant Impulse Noise (BLAST WAVES) on Hearing: Parametric Studies

    DTIC Science & Technology

    1993-06-16

    high levels of reverberant impulse noise using an animal ( chinchilla ) model. The blast waves were generated by a three inch diameter shock tube...found in previous contractor reports (Hamernik et al., ADA 203-854, ADA 206-180 and ADA 221-731). (a) Subjeeta : The chinchilla was used...as the experimental animal. Over the years, the chinchilla has been used in a wide variety of auditory experiments and consequently, much

  1. 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.

  2. 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.

  3. 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

  4. On the interaction between blast wave and reticulated foams

    NASA Astrophysics Data System (ADS)

    Wilgeroth, James; Proud, William; Ngoc Nguyen, Thuy-Tien; Institute of Shock Physics Team; CentreBlast Injury Studies Team

    2013-06-01

    Injuries to the tympanic membrane (ear drum) and inner ear are particularly common in individuals subjected to blast overpressure, such as military personnel engaged in conflict. Consequently, there is a demand for improved auditory protection systems, which are capable of both preventing this type of injury while providing maximum situational awareness to the user. In this study, a number of reticulated (open cell) foams have been subjected to dynamic compression using shock tube apparatus. Specific effects of porosity; relative density, which is determined by the ratio of cellular material to solid material from which the foam is made; sample thickness; incident pressure; and shock pulses of varying timescale upon the evolution of peak overpressure behind foam samples have been investigated. In addition, the use of Schlieren imaging techniques has allowed for detailed examination of gaseous flow at the rear surface of shocked foam samples.

  5. 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.

  6. Computational Modeling of Causal Mechanisms of Blast Wave Induced Traumatic Brain Injury - A Potential Tool for Injury Prevention

    DTIC Science & Technology

    2009-10-01

    Bowen et al. 1968).The stand-off distance and the net weight of the explosive ( TNT equivalence ) needed to match four levels of overpressure and...wave profiles based on Bowen’s iso-damage curve (Figure 1). Table 1: Calculated stand-off distance and TNT equivalent to match the blast effect...spherical TNT . Table 1 lists the calculated weight of the spherical TNT explosive and the corresponding stand-off distance required to produce four blast

  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. 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.

  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. KANTBP 3.0: New version of a program for computing energy levels, reflection and transmission matrices, and corresponding wave functions in the coupled-channel adiabatic approach

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    A FORTRAN program for calculating energy values, reflection and transmission matrices, and corresponding wave functions in a coupled-channel approximation of the adiabatic approach is presented. In this approach, a multidimensional Schrödinger equation is reduced to a system of the coupled second-order ordinary differential equations on a finite interval with the homogeneous boundary conditions of the third type at the left- and right-boundary points for continuous spectrum problem. The resulting system of these 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 reflection and transmission matrices and corresponding wave functions for the two-dimensional problem with different barrier potentials.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Modeling Nonlinear Acoustical Blast Waves Outdoors: A Research Summary

    DTIC Science & Technology

    1991-09-01

    Porous Surfaces. 5 David Gottlieb and Eli Turkel, "Dissipative Two-Four Methods for Time Dependent Problems," Mathematical Comnputation, No. 30 (1976...or structure factor, which Attenborough relates to the tortuosity. The local reaction assumption is inhereptly built into this model of the porous...k Waves in the Atmosphere," Journal of the Acoustical Socidy of America, No. 74 (1983). pp 1514-1517. David T. Blackstone., "Nonlinear Acoustics

  17. Regional Surface Waves from Mesabi Range Mine Blasts (Northern Minnesota)

    DTIC Science & Technology

    1991-10-29

    igneous body, so it is realistic to assume there are Keweenawan igneous rocks within the eastern Animikie basin, which surface waves generated at Erie and...velocity inversion which, as the wedge thickens, will advance high frequencies relative to low frequencies. The data fit this interpretation, except...1569, U.S. Nuclear Regulatory Commission, 85 p. Morey, G.B., 1972, Petrology of Keweenawan sandstones in the subsurface of southeastern Minnesota, in

  18. Shock Tube Simulation of Low Mach Number Blast Waves

    NASA Astrophysics Data System (ADS)

    Morgan, R. G.; Gildfind, D. E.

    The underground mining environment has always been high risk due to the presence of solid and gaseous flammables, and the potential for the creation of detonablemixtures. Following explosions in confined spaces, shock waves are generated and may propagate through the tunnel system, causing injuries and possibly initiating further combusting or detonating events. The ability to generate the conditions which exist post shock is a useful experimental tool for the study of such processes, and for the evaluation of techniques to control and limit propagation.

  19. Blast Overpressure Studies with Animals and Man: Biological Response to Complex Blast Waves

    DTIC Science & Technology

    1993-10-31

    enclosure produce lung injury in rabbits at one -fifth the peak overpressure required for a simple wave. 2 It was suggested that the frequency content of the...Whereas i the lung hemorrhage was confined to the right lung exclusively in the sheep exposed right-side- on to the explosion outdoors in the 3 4I U...to 4.88 x 3.05 x 2.44 m (36.3 m^3), and for D it was 3.05 x 1.52 x 2.44 m (11.3 m^3). A turbine ventilator was mounted on one of I the roof sections

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Computational Study of Thrust Generation from Laser-Driven Blast Wave

    SciTech Connect

    Ohnishi, Naofumi; Ogino, Yousuke

    2008-04-28

    We have performed axisymmetric simulations in order to investigate the thrust generation resulting from the interference between the projectile and the blast wave produced by a pulsed laser. The results obtained by our numerical code well agree for the pressure history and the momentum coupling coefficient with the experimental data. In such analysis, it is found that the approximate impulse estimated only by the pressure history at the projectile base is difficult to predict the actual one. Since the shock wave rapidly attenuates in low fill pressure, and the interaction with the projectile almost finishes in the shroud, a high momentum coupling coefficient can be achieved unlike the case of high fill pressure in which the projectile experiences the subsequent negative thrust.

  5. Structural Changes in Lipid Vesicles Generated by the Shock Blast Waves: Coarse-Grained Molecular Dynamics Simulation

    DTIC Science & Technology

    2013-11-01

    TERMS TBI, liposome , cellular membrane, simulation, computation 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF...Friedlander waveform (3). ..................................1 Figure 2. The snapshot of the lipid vesicle ( liposome ): (a) the liposome is composed...shock blast wave at the various distances from its launch. The liposome location corresponds to the magenta curve. The second peak in blue and magenta

  6. 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.

  7. 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.

  8. Blast waves from detonated military explosive reduce GluR1 and synaptophysin levels in hippocampal slice cultures.

    PubMed

    Smith, Marquitta; Piehler, Thuvan; Benjamin, Richard; Farizatto, Karen L; Pait, Morgan C; Almeida, Michael F; Ghukasyan, Vladimir V; Bahr, Ben A

    2016-12-01

    Explosives create shockwaves that cause blast-induced neurotrauma, one of the most common types of traumatic brain injury (TBI) linked to military service. Blast-induced TBIs are often associated with reduced cognitive and behavioral functions due to a variety of factors. To study the direct effects of military explosive blasts on brain tissue, we removed systemic factors by utilizing rat hippocampal slice cultures. The long-term slice cultures were briefly sealed air-tight in serum-free medium, lowered into a 37°C water-filled tank, and small 1.7-gram assemblies of cyclotrimethylene trinitramine (RDX) were detonated 15cm outside the tank, creating a distinct shockwave recorded at the culture plate position. Compared to control mock-treated groups of slices that received equal submerge time, 1-3 blast impacts caused a dose-dependent reduction in the AMPA receptor subunit GluR1. While only a small reduction was found in hippocampal slices exposed to a single RDX blast and harvested 1-2days later, slices that received two consecutive RDX blasts 4min apart exhibited a 26-40% reduction in GluR1, and the receptor subunit was further reduced by 64-72% after three consecutive blasts. Such loss correlated with increased levels of HDAC2, a histone deacetylase implicated in stress-induced reduction of glutamatergic transmission. No evidence of synaptic marker recovery was found at 72h post-blast. The presynaptic marker synaptophysin was found to have similar susceptibility as GluR1 to the multiple explosive detonations. In contrast to the synaptic protein reductions, actin levels were unchanged, spectrin breakdown was not detected, and Fluoro-Jade B staining found no indication of degenerating neurons in slices exposed to three RDX blasts, suggesting that small, sub-lethal explosives are capable of producing selective alterations to synaptic integrity. Together, these results indicate that blast waves from military explosive cause signs of synaptic compromise without

  9. 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

  10. 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.

  11. 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.

  12. Seismic-wave generation and propagation from coal-mine blasts at the Wright Mine, Warrick County, Indiana. Final report

    SciTech Connect

    Braile, L.W.; Sexton, J.L.; Martindale, K.W.; Chiang, C.S.

    1982-03-01

    The objectives of study of seismic wave generation and propagation surrounding the Wright Mine blasts were: document the level of ground vibration surrounding the Wright Mine including frequency content, duration, peak acceleration, velocity and displacement; relate ground-motion measurements to shot size, local geologic conditions (particularly individual site responses), and possible variations in ground-vibration measurements for different directions from the blasts; relate the levels of ground-vibration observations to standards of perception and damage based on United States Bureau of Mines studies. It should be noted that no observations of possible damage nor perception were made and no seismograph recordings or other observations were made within structures surrounding the Wright Mine. The authors objective was strictly to document the ground vibration characteristics caused by Wright Mine blasts.

  13. 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.

  14. 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.

  15. Blast wave mitigation by dry aqueous foam: numerical modelling and experimental investigation

    NASA Astrophysics Data System (ADS)

    Counilh, Denis; Ballanger, Felix; Rambert, Nicolas; Haas, Jean-Francois; Chinnayya, Aschwin; Lefrancois, Alexandre

    2016-11-01

    Dry aqueous foams (two-phase media with water liquid fraction lower than 5%) are known to mitigate blast wave effects induced by an explosion. The CEA has calibrated his numerical multiphase code MOUSSACA from shock tube and high-explosive experiments. The shock tube experiments have highlighted the foam fragmentation into droplets and the momentum transfer between the liquid and gas phases of the foam. More recently, experiments with hemispheric explosive charges from 3 g to 120 g have provided more findings about the pressure and impulse mitigation properties of foams. We have also taken into account the heat and mass transfer, as well as the droplets secondary breakup, characterized by the Weber number, ratio of inertia over surface tension. Good agreement is found between the calculation and the experiments. co-supervisor of the Felix Ballanger 's doctoral thesis.

  16. 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.

  17. Coupled 3D time-dependent wave-packet approach in hyperspherical coordinates: application to the adiabatic singlet-state(1(1)A') D(+) + H2 reaction.

    PubMed

    Sahoo, Tapas; Ghosh, Sandip; Adhikari, Satrajit; Sharma, Rahul; Varandas, António J C

    2014-07-03

    We explore a coupled three-dimensional (3D) time-dependent wave packet formalism in hyperspherical coordinates for a 4D reactive scattering problem on the lowest adiabatic singlet surface (1(1)A') of the D(+) + H2 reaction. The coupling among the wavepackets arises through quantization of the rotation matrix, which represents the orientation of the three particles in space. The required transformation from Jacobi to hyperspherical coordinates and vice versa during initialization and projection of the wave packet on the asymptotic state(s), and the coupled equations of motion, are briefly discussed. With the long-range potential known to contribute significantly on the D(+) + H2 system, we demonstrate the workability of our approach, where the convergence profiles of the reaction probability for the reactive noncharge transfer (RNCT) process [D(+) + H2(v=0, j=0,1) → HD(v',j') + H(+)] are shown for three different collisional energies (1.7, 2.1, and 2.5 eV) with respect to the helicity (K) and total angular momentum (J) quantum numbers. The calculated reactive cross-section is presented as a function of the collision energy for two different initial states of the diatom (v = 0, j = 0, 1).

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

    PubMed Central

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

    2015-01-01

    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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Direct simulations of outdoor blast wave propagation from source to receiver

    NASA Astrophysics Data System (ADS)

    Nguyen-Dinh, M.; Lardjane, N.; Duchenne, C.; Gainville, O.

    2017-02-01

    Outdoor blast waves generated by impulsive sources are deeply affected by numerous physical conditions such as source shape or height of burst in the near field, as well as topography, ground nature, or atmospheric conditions at larger distances. Application of classical linear acoustic methods may result in poor estimates of peak overpressures at intermediate ranges in the presence of these conditions. Here, we show, for the first time, that converged direct fully nonlinear simulations can be produced at a reasonable CPU cost in two-dimensional axisymmetric geometry from source location to more than 500 m/kg^{1/3} . The numerical procedure is based on a high-order finite-volume method with adaptive mesh refinement for solving the nonlinear Euler equations with a detonation model. It is applied to a real outdoor pyrotechnic site. A digital terrain model is built, micro-meteorological conditions are included through an effective sound speed, and a ground roughness model is proposed in order to account for the effects of vegetation and unresolved scales. Two-dimensional axisymmetric simulations are performed for several azimuths, and a comparison is made with experimental pressure signals recorded at scaled distances from 36 to 504 m/kg^{1/3} . The relative importance of the main physical effects is discussed.

  8. 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.

  9. a Finite Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces

    NASA Astrophysics Data System (ADS)

    Sparrow, Victor Ward

    1990-01-01

    This study has concerned the propagation of finite amplitude, i.e. weakly non-linear, acoustical blast waves from explosions over hard and porous media models of outdoor ground surfaces. The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous ground surface, which in the frequency domain exhibits a finite impedance, the linear phenomenological porous model of Morse and Ingard was used. The phenomenological equations are solved in the time domain for coupling with the time domain propagation solution in the air. The numerical solution is found through the method of finite differences. The second-order in time and fourth -order in space MacCormack method was used in the air, and the second-order in time and space MacCormack method was used in the porous medium modeling the ground. Two kinds of numerical absorbing boundary conditions were developed for the air propagation equations to truncate the physical domain for solution on a computer. Radiation conditions first were used on those sides of the domain where there were outgoing waves. Characteristic boundary conditions secondly are employed near the acoustic source. The numerical model agreed well with the Pestorius algorithm for the propagation of electric spark pulses in the free field, and with a result of Pfriem for normal plane reflection off a hard surface. In addition, curves of pressure amplification versus incident angle for waves obliquely incident on the hard and porous surfaces were produced which are similar to those in the literature. The model predicted that near grazing finite amplitude acoustic blast waves decay with distance over hard surfaces as r to the power -1.2. This result is consistent with the work of Reed. For propagation over the porous ground surface, the model predicted that this surface decreased the decay rate with distance for the larger blasts compared to the rate expected in the linear acoustics limit.

  10. Optimizing Adiabaticity in NMR

    NASA Astrophysics Data System (ADS)

    Vandermause, Jonathan; Ramanathan, Chandrasekhar

    We demonstrate the utility of Berry's superadiabatic formalism for numerically finding control sequences that implement quasi-adiabatic unitary transformations. Using an iterative interaction picture, we design a shortcut to adiabaticity that reduces the time required to perform an adiabatic inversion pulse in liquid state NMR. We also show that it is possible to extend our scheme to two or more qubits to find adiabatic quantum transformations that are allowed by the control algebra, and demonstrate a two-qubit entangling operation in liquid state NMR. We examine the pulse lengths at which the fidelity of these adiabatic transitions break down and compare with the quantum speed limit.

  11. Adiabatic heating in impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Maetzler, C.; Bai, T.; Crannell, C. J.; Frost, K. J.

    1977-01-01

    The dynamic X-ray spectra of two simple, impulsive solar flares are examined together with H alpha, microwave and meter wave radio observations. X-ray spectra of both events were characteristic of thermal bremsstrahlung from single temperature plasmas. The symmetry between rise and fall was found to hold for the temperature and emission measure. The relationship between temperature and emission measure was that of an adiabatic compression followed by adiabatic expansion; the adiabatic index of 5/3 indicated that the electron distribution remained isotropic. Observations in H alpha provided further evidence for compressive energy transfer.

  12. The effect of initial conditions on the nonlinear evolution of perturbed interfaces driven by strong blast waves

    NASA Astrophysics Data System (ADS)

    Miles, Aaron R.

    2004-08-01

    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

  13. 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

  14. Near-field investigation of the explosive dispersal of radioactive material based on a reconstructed spherical blast-wave flow.

    PubMed

    Hummel, David; Ivan, Lucian

    2017-03-15

    A "dirty bomb" is a type of radiological dispersal device (RDD) that has been the subject of significant safety and security concerns given the disruption that would result from a postulated terrorist attack. Assessing the risks of radioactive dose in a hypothetical scenario requires models that can accurately predict dispersion in a realistic environment. Modelling a RDD is complicated by the fact that the most important phenomena occur over vastly disparate spatial and temporal length scales. Particulate dispersion in the air is generally considered on scales of hundreds to thousands of meters, and over periods of minutes and hours. Dispersion models are extremely sensitive, however, to the particle size and source characterization, which are determined in distances measured in micrometers to meters, over milliseconds or less. This study examines the extent to which the explosive blast determines the transport of contaminant particles relative to the atmospheric wind over distances relevant to "near-field" dispersion problems (i.e., hundreds of meters), which are relevant to urban environments. Our results indicate that whether or not the effect of the blast should be included in a near-field dispersion model is largely dependent on the size of the contaminant particle. Relatively large particles (i.e., >40 μm in diameter), which are most likely to be produced by a RDD, penetrate the leading shock front, thereby avoiding the reverse blast wind. Consequently, they travel much farther than suspended aerosols (<10 μm) before approaching the ambient wind velocity. This suggests that, for these "near-field" dispersion problems in urban environments, the transport of contaminants from the blast wave may be integral to accurately predicting their dispersion.

  15. 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.

  16. 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

  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.

  19. 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.

  20. Theory of Adiabatic Fountain Resonance

    NASA Astrophysics Data System (ADS)

    Williams, Gary A.

    2017-01-01

    The theory of "Adiabatic Fountain Resonance" with superfluid ^4{He} is clarified. In this geometry a film region between two silicon wafers bonded at their outer edge opens up to a central region with a free surface. We find that the resonance in this system is not a Helmholtz resonance as claimed by Gasparini et al., but in fact is a fourth sound resonance. We postulate that it occurs at relatively low frequency because the thin silicon wafers flex appreciably from the pressure oscillations of the sound wave.

  1. 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

  2. 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.

  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 Periodic Oscillation of an Adiabatic Piston in Two or Three Dimensions

    NASA Astrophysics Data System (ADS)

    Shi, Yanchao; Hao, Hong; Li, Zhong-Xian

    2007-08-01

    Accurate estimation of blast loads on structures is essential for reliable predictions of structural response and damage. Current practice in blast effect analysis and design estimates blast loads primarily based on empirical formulae obtained from field blast tests. Due to the limited availability of test data, those empirical formulae are usually applicable to the case that the reflection surface of the structure is big enough so that no wave diffraction around the structure exists. They will overestimate the blast loads on structure columns without infill walls around them, which are very common in the modern buildings, especially for the ground floor columns. For a standalone column, the initial reflected pressure may be quickly relieved at the edge of the column, and the column will be engulfed with the blast wave due to diffraction. Therefore, the interaction between the blast wave and structure is important for such columns. The blast loads on such columns will be different from those obtained in field blasting tests on walls. There is no method in the open literature to estimate blast loads on standalone columns. In the present study, interactions between blast waves and structure columns are simulated using AUTODYN 3D. The influence of the scaled distance of the blast, column stiffness, ratio of the supported mass to the column mass, and column dimension and geometry, on the blast wave column interaction is investigated. Based on the numerical simulation results, some formulae are proposed to estimate the blast pressure, impulse, and the reflected pressure time history on standalone structure columns.

  5. Controlled Low-Pressure Blast-Wave Exposure Causes Distinct Behavioral and Morphological Responses Modelling Mild Traumatic Brain Injury, Post-Traumatic Stress Disorder, and Comorbid Mild Traumatic Brain Injury-Post-Traumatic Stress Disorder.

    PubMed

    Zuckerman, Amitai; Ram, Omri; Ifergane, Gal; Matar, Michael A; Sagi, Ram; Ostfeld, Ishay; Hoffman, Jay R; Kaplan, Zeev; Sadot, Oren; Cohen, Hagit

    2017-01-01

    The intense focus in the clinical literature on the mental and neurocognitive sequelae of explosive blast-wave exposure, especially when comorbid with post-traumatic stress-related disorders (PTSD) is justified, and warrants the design of translationally valid animal studies to provide valid complementary basic data. We employed a controlled experimental blast-wave paradigm in which unanesthetized animals were exposed to visual, auditory, olfactory, and tactile effects of an explosive blast-wave produced by exploding a thin copper wire. By combining cognitive-behavioral paradigms and ex vivo brain MRI to assess mild traumatic brain injury (mTBI) phenotype with a validated behavioral model for PTSD, complemented by morphological assessments, this study sought to examine our ability to evaluate the biobehavioral effects of low-intensity blast overpressure on rats, in a translationally valid manner. There were no significant differences between blast- and sham-exposed rats on motor coordination and strength, or sensory function. Whereas most male rats exposed to the blast-wave displayed normal behavioral and cognitive responses, 23.6% of the rats displayed a significant retardation of spatial learning acquisition, fulfilling criteria for mTBI-like responses. In addition, 5.4% of the blast-exposed animals displayed an extreme response in the behavioral tasks used to define PTSD-like criteria, whereas 10.9% of the rats developed both long-lasting and progressively worsening behavioral and cognitive "symptoms," suggesting comorbid PTSD-mTBI-like behavioral and cognitive response patterns. Neither group displayed changes on MRI. Exposure to experimental blast-wave elicited distinct behavioral and morphological responses modelling mTBI-like, PTSD-like, and comorbid mTBI-PTSD-like responses. This experimental animal model can be a useful tool for elucidating neurobiological mechanisms underlying the effects of blast-wave-induced mTBI and PTSD and comorbid mTBI-PTSD.

  6. 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.

  7. Circulation in blast driven instabilities

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, Marc; Johnsen, Eric

    2016-11-01

    Mixing in many natural phenomena (e.g. supernova collapse) and engineering applications (e.g. inertial confinement fusion) is often initiated through hydrodynamic instabilities. Explosions in these systems give rise to blast waves which can interact with perturbations at interfaces between different fluids. Blast waves are formed by a shock followed by a rarefaction. This wave profile leads to complex time histories of interface acceleration. In addition to the instabilities induced by the acceleration field, the rarefaction from the blast wave decompresses the material at the interface, further increasing the perturbation growth. After the passage of the wave, circulation circulation generated by the blast wave through baroclinic vorticity continues to act upon the interface. In this talk, we provide scaling laws for the circulation and amplitude growth induced by the blast wave. Numerical simulations of the multifluid Euler equations solved using a high-order accurate Discontinuous Galerkin method are used to validate the theoretical results.

  8. 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

  9. Quantum adiabatic machine learning

    NASA Astrophysics Data System (ADS)

    Pudenz, Kristen L.; Lidar, Daniel A.

    2013-05-01

    We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. This approach consists of two quantum phases, with some amount of classical preprocessing to set up the quantum problems. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. All quantum processing is strictly limited to two-qubit interactions so as to ensure physical feasibility. We apply and illustrate this approach in detail to the problem of software verification and validation, with a specific example of the learning phase applied to a problem of interest in flight control systems. Beyond this example, the algorithm can be used to attack a broad class of anomaly detection problems.

  10. 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.

  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. 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.

  13. Ultrafast adiabatic second harmonic generation

    NASA Astrophysics Data System (ADS)

    Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim

    2017-03-01

    We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.

  14. Ultrafast adiabatic second harmonic generation.

    PubMed

    Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim

    2017-03-01

    We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.

  15. 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.

  16. 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.

  17. Acceleration of adiabatic quantum dynamics in electromagnetic fields

    SciTech Connect

    Masuda, Shumpei; Nakamura, Katsuhiro

    2011-10-15

    We show a method to accelerate quantum adiabatic dynamics of wave functions under electromagnetic field (EMF) by developing the preceding theory [Masuda and Nakamura, Proc. R. Soc. London Ser. A 466, 1135 (2010)]. Treating the orbital dynamics of a charged particle in EMF, we derive the driving field which accelerates quantum adiabatic dynamics in order to obtain the final adiabatic states in any desired short time. The scheme is consolidated by describing a way to overcome possible singularities in both the additional phase and driving potential due to nodes proper to wave functions under EMF. As explicit examples, we exhibit the fast forward of adiabatic squeezing and transport of excited Landau states with nonzero angular momentum, obtaining the result consistent with the transitionless quantum driving applied to the orbital dynamics in EMF.

  18. 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.

  19. Semiconductor adiabatic qubits

    DOEpatents

    Carroll, Malcolm S.; Witzel, Wayne; Jacobson, Noah Tobias; Ganti, Anand; Landahl, Andrew J.; Lilly, Michael; Nguyen, Khoi Thi; Bishop, Nathaniel; Carr, Stephen M.; Bussmann, Ezra; Nielsen, Erik; Levy, James Ewers; Blume-Kohout, Robin J.; Rahman, Rajib

    2016-12-27

    A quantum computing device that includes a plurality of semiconductor adiabatic qubits is described herein. The qubits are programmed with local biases and coupling terms between qubits that represent a problem of interest. The qubits are initialized by way of a tuneable parameter, a local tunnel coupling within each qubit, such that the qubits remain in a ground energy state, and that initial state is represented by the qubits being in a superposition of |0> and |1> states. The parameter is altered over time adiabatically or such that relaxation mechanisms maintain a large fraction of ground state occupation through decreasing the tunnel coupling barrier within each qubit with the appropriate schedule. The final state when tunnel coupling is effectively zero represents the solution state to the problem represented in the |0> and |1> basis, which can be accurately read at each qubit location.

  20. 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

  1. Blast Injury

    PubMed Central

    de Candole, C. A.

    1967-01-01

    The shock wave generated by an explosion (“blast wave”) may cause injury in any or all of the following: (1) direct impact on the tissues of variations in environmental pressure; (2) flying glass and other debris set in motion by it; (3) propulsion of the body. Injuries in the first category affect gas-containing organs (ears, lungs and intestines), and acute death is attributed to air forced into the coronary vessels via damaged pulmonary alveoli. It is estimated that overpressure sufficient to cause lung injury may occur up to five miles from a 20-megaton nuclear explosion. The greatest single hazard from blast is, however, flying glass, and serious wounding from this cause is possible up to 12 miles from an explosion of this magnitude. PMID:6015742

  2. The synchrotron self-Compton spectrum of relativistic blast waves at large Y

    NASA Astrophysics Data System (ADS)

    Lemoine, Martin

    2015-11-01

    Recent analyses of multiwavelength light curves of gamma-ray bursts afterglows point to values of the magnetic turbulence well below the canonical ˜1 per cent of equipartition, in agreement with theoretical expectations of a microturbulence generated in the shock precursor, which then decays downstream of the shock front through collisionless damping. As a direct consequence, the Compton parameter Y can take large values in the blast. In the presence of decaying microturbulence and/or as a result of the Klein-Nishina suppression of inverse Compton cooling, the Y parameter carries a non-trivial dependence on the electron Lorentz factor, which modifies the spectral shape of the synchrotron and inverse Compton components. This paper provides detailed calculations of this synchrotron self-Compton spectrum in this large Y regime, accounting for the possibility of decaying microturbulence. It calculates the expected temporal and spectral indices α and β customarily defined by F_ν ∝ t_obs^{-α }ν ^{-β } in various spectral domains. This paper also makes predictions for the very high energy photon flux; in particular, it shows that the large Y regime would imply a detection rate of gamma-ray bursts at >10 GeV several times larger than currently anticipated.

  3. 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.

  4. On Adiabatic Pair Creation

    NASA Astrophysics Data System (ADS)

    Pickl, Peter; Dürr, Detlef

    2008-08-01

    We give here a rigorous proof of the well known prediction of pair creation as it arises from the Dirac equation with an external time dependent potential. Pair creation happens with probability one if the potential changes adiabatically in time and becomes overcritical, which means that an eigenvalue curve (as a function of time) bridges the gap between the negative and positive spectral continuum. The potential can be thought of as being zero at large negative and large positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Süßmann [1] in 1963 and Gershtein and Zeldovich [8] in 1970.

  5. 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.

  6. 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

  7. Adiabatic state preparation study of methylene

    SciTech Connect

    Veis, Libor Pittner, Jiří

    2014-06-07

    Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.

  8. 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.

  9. 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.

  10. 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.

  11. State-resolved time-dependent wave packet and quasiclassical trajectory studies of the adiabatic reaction S(3P) + HD on the (1(3)A″) state.

    PubMed

    Cheng, Dahai; Yuan, Jiuchuang; Chen, Maodu

    2014-01-09

    Time-dependent wave packet (TDWP) and quasiclassical trajectory (QCT) calculations have been carried out for the reaction S(3P) + HD(X1Σg+) at the lowest 13A″ state with both rotational and vibrational excitations of reactant HD. The calculated integral cross sections from QCT agree fairly well with the TDWP calculations. The reaction probability results from TDWP show that the reaction displays a strong tendency to the SD channel. When the reactant HD is vibrationally excited, both channels are promoted apparently. The vibration of the HD bond tends to reduce the difference of reactivity between the two channels. The detailed state-to-state differential cross sections (DCSs) are calculated. These distributions show some significant characters of the barrier-type reactions. At the same time, the scattering width of product SD has a certain relationship with its rotation excitation. For the vector properties, P(θr), P(r), and P(θr,r) distributions are calculated by QCT, and the increased collision energy weakens the rotational polarization of the SD molecule.

  12. Origin of asymmetries in X-ray emission lines from the blast wave of the 2014 outburst of nova V745 Sco

    NASA Astrophysics Data System (ADS)

    Orlando, Salvatore; Drake, Jeremy J.; Miceli, Marco

    2017-02-01

    The symbiotic nova V745 Sco was observed in outburst on 2014 February 6. Its observations by the Chandra X-ray Observatory at days 16 and 17 have revealed a spectrum characterized by asymmetric and blueshifted emission lines. Here we investigate the origin of these asymmetries through 3D hydrodynamic simulations describing the outburst during the first 20 d of evolution. The model takes into account thermal conduction and radiative cooling, and assumes that a blast wave propagates through an equatorial density enhancement (EDE). From these simulations, we synthesize the X-ray emission and derive the spectra as they would be observed with Chandra. We find that both the blast wave and the ejecta distribution are efficiently collimated in polar directions due to the presence of the EDE. The majority of the X-ray emission originates from the interaction of the blast with the EDE and is concentrated on the equatorial plane as a ring-like structure. Our `best-fitting' model requires a mass of ejecta in the outburst Mej ≈ 3 × 10-7 M⊙ and an explosion energy Eb ≈ 3 × 1043 erg, and reproduces the distribution of emission measure versus temperature and the evolution of shock velocity and temperature inferred from the observations. The model predicts asymmetric and blueshifted line profiles similar to those observed and explains their origin as due to substantial X-ray absorption of redshifted emission by ejecta material. The comparison of predicted and observed Ne and O spectral line ratios reveals no signs of strong Ne enhancement and suggests that the progenitor is a CO white dwarf.

  13. 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.…

  14. 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.

  15. 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.

  16. 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...

  17. Exit from inflation with a first-order phase transition and a gravitational wave blast

    NASA Astrophysics Data System (ADS)

    Ashoorioon, Amjad

    2015-07-01

    In double-field inflation, which exploits two scalar fields, one of the fields rolls slowly during inflation whereas the other field is trapped in a meta-stable vacuum. The nucleation rate from the false vacuum to the true one becomes substantial enough that triggers a first order phase transition and ends inflation. We revisit the question of first order phase transition in an "extended" model of hybrid inflation, realizing the double-field inflationary scenario, and correctly identify the parameter space that leads to a first order phase transition at the end of inflation. We compute the gravitational wave profile which is generated during this first order phase transition. Assuming instant reheating, the peak frequency falls in the 1 GHz to 10 GHz frequency band and the amplitude varies in the range 10-11 ≲ΩGWh2 ≲10-8, depending on the value of the cosmological constant in the false vacuum. For a narrow band of vacuum energies, the first order phase transition can happen after the end of inflation via the violation of slow-roll, with a peak frequency that varies from 1 THz to 100 THz. For smaller values of cosmological constant, even though inflation can end via slow-roll violation, the universe gets trapped in a false vacuum whose energy drives a second phase of eternal inflation. This range of vacuum energies do not lead to viable inflationary models, unless the value of the cosmological constant is compatible with the observed value, M ∼10-3 eV.

  18. 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.

  19. 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

  20. 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.

  1. The Floquet Adiabatic Theorem revisited

    NASA Astrophysics Data System (ADS)

    Weinberg, Phillip; Bukov, Marin; D'Alessio, Luca; Kolodrubetz, Michael; Davidson, Shainen; Polkovnikov, Anatoli

    2015-03-01

    The existance of the adiabatic theorem for Floquet systems has been the subject of an active debate with different articles reaching opposite conclusions over the years. In this talk we clarify the situation by deriving a systematic expansion in the time-derivatives of a slow parameter for the occupation probabilities of the Floque states. Our analysis shows that the in a certain limit the transition between Floquet eigenstates are suppressed and it is possible to define an adiabatic theorem for Floquet systems. Crucially we observe however that the conditions for adiabaticity in ordinary and Floquet systems are different and that this difference can become important when the amplitude of the periodic driving is large. We illustrate our results with specific examples of a periodically driven harmonic oscillator and cold atoms in optical lattices which are relevant in current experiments.

  2. Adiabatic losses in Stirling refrigerators

    SciTech Connect

    Bauwens, L.

    1996-06-01

    The Stirling cycle has been used very effectively in cryocoolers; but efficiencies relative to the Carnot limit are typically observed to peak for absolute temperature ratios of about two, which makes it less suitable for low-life refrigeration. The adiabatic loss appears to be responsible for poor performance at small temperature differences. In this paper, adiabatic losses are evaluated, for a temperature ratio of 2/3, taking into account the effect of phase angle between pistons, of volume ratio, of the distribution of the dead volume necessary to reduce the volume ratio, and of the distribution of displacement between expansion and compression spaces. The study is carried out numerically, using an adiabatic Stirling engine model in which cylinder flow is assumed to be stratified. Results show that the best location for the cylinder dead volume is on the compression side. Otherwise, all strategies used to trade off refrigeration for coefficient of performance are found to be roughly equivalent.

  3. 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

  4. The formation of multiple adiabatic shear bands

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Wright, T. W.; Ramesh, K. T.

    2006-07-01

    In a previous paper, Zhou et al. [2006. A numerical methodology for investigating adiabatic shear band formation. J. Mech. Phys. Solids, 54, 904-926] developed a numerical method for analyzing one-dimensional deformation of thermoviscoplastic materials. The method uses a second order algorithm for integration along characteristic lines, and computes the plastic flow after complete localization with high resolution and efficiency. We apply this numerical scheme to analyze localization in a thermoviscoplastic material where multiple shear bands are allowed to form at random locations in a large specimen. As a shear band develops, it unloads neighboring regions and interacts with other bands. Beginning with a random distribution of imperfections, which might be imagined as arising qualitatively from the microstructure, we obtain the average spacing of shear bands through calculations and compare our results with previously existing theoretical estimates. It is found that the spacing between nucleating shear bands follows the perturbation theory due to Wright and Ockendon [1996. A scaling law for the effect of inertia on the formation of adiabatic shear bands. Int. J. Plasticity 12, 927-934], whereas the spacing between mature shear bands is closer to that predicted by the momentum diffusion theory of Grady and Kipp [1987. The growth of unstable thermoplastic shear with application to steady-wave shock compression in solids. J. Mech. Phys. Solids 35, 95-119]. Scaling laws for the dependence of band spacing on material parameters differ in many respects from either theory.

  5. 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…

  6. 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.

  7. Transitionless driving on adiabatic search algorithm

    NASA Astrophysics Data System (ADS)

    Oh, Sangchul; Kais, Sabre

    2014-12-01

    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. Transitionless driving on adiabatic search algorithm.

    PubMed

    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.

  9. Digital waveguide adiabatic passage part 1: theory

    NASA Astrophysics Data System (ADS)

    Vaitkus, Jesse A.; Steel, M. J.; Greentree, Andrew D.

    2017-03-01

    Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.

  10. Adiabatic far-field sub-diffraction imaging.

    PubMed

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

    2015-08-10

    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.

  11. 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

  12. Breaking of dynamical adiabaticity in direct laser acceleration of electrons

    NASA Astrophysics Data System (ADS)

    Robinson, A. P. L.; Arefiev, A. V.

    2017-02-01

    The interaction of an electron oscillating in an ion channel and irradiated by a plane electromagnetic wave is considered. It is shown that the interaction qualitatively changes with the increase of electron energy, as the oscillations across the channel become relativistic. The "square-wave-like" profile of the transverse velocity in the relativistic case enables breaking of the adiabaticity that precludes electron energy retention in the non-relativistic case. For an electron with a relativistic factor γ0, the adiabaticity breaks if ωL/ωp0≪√{γ0 } . Under these conditions, the kinetic energy acquired by the electron is retained once the interaction with the laser field ceases. This mechanism notably enables electron heating in regimes that do not require a resonant interaction between the initially oscillating electron and the laser electric field.

  13. Attenuation of strong external blast by foam barriers

    NASA Astrophysics Data System (ADS)

    Sembian, S.; Liverts, M.; Apazidis, N.

    2016-09-01

    The mitigation of externally generated strong blast waves by an aqueous foam barrier of varying configurations within fixed distance between the explosion origin and the object to be protected is investigated and quantified both experimentally and numerically. The blast waves of shock Mach number 4.8 at 190 mm from the explosion plane are generated using exploding wire technique. The initially cylindrical blast waves are transformed into a plane blast wave in a specially constructed test unit in which the experiments are performed. The shock waves emanating from the foam barrier are captured using shadowgraph technique. A simple numerical model treating the foam by a pseudo-gas approach is used in interpreting and re-constructing the experimental results. The additional contribution of the impedance mismatch factor is analysed with the aid of numerical simulation and exploited for achieving greater blast wave pressure reduction.

  14. Molecular Signatures and Diagnostic Biomarkers of Cumulative Blast-Graded Mild TBI

    DTIC Science & Technology

    2014-12-01

    measured by calibrated activated thrombography ( CAT ), linked to microcirculation disorders following blast exposures. In addition, we developed...Table 2. Indices of Thrombin Activity after Exposure to a Primary/Composite Blast Wave Load. Pr im ar y B la st CAT parameter...4.5 + 0.15* 4.0 + 0.13* C om po si te B la st CAT parameter Baseline 6 hr post-blast 1 day post-blast 7 days post-blast TG max

  15. Neurological Effects of Blast Injury

    PubMed Central

    Hicks, Ramona R.; Fertig, Stephanie J.; Desrocher, Rebecca E.; Koroshetz, Walter J.; Pancrazio, Joseph J.

    2010-01-01

    Over the last few years, thousands of soldiers and an even greater number of civilians have suffered traumatic injuries due to blast exposure, largely attributed to improvised explosive devices in terrorist and insurgent activities. The use of body armor is allowing soldiers to survive blasts that would otherwise be fatal due to systemic damage. Emerging evidence suggests that exposure to a blast can produce neurological consequences in the brain, but much remains unknown. To elucidate the current scientific basis for understanding blast-induced traumatic brain injury (bTBI), the NIH convened a workshop in April, 2008. A multidisciplinary group of neuroscientists, engineers, and clinicians were invited to share insights on bTBI, specifically pertaining to: physics of blast explosions, acute clinical observations and treatments, preclinical and computational models, and lessons from the international community on civilian exposures. This report provides an overview of the state of scientific knowledge of bTBI, drawing from the published literature, as well as presentations, discussions, and recommendations from the workshop. One of the major recommendations from the workshop was the need to characterize the effects of blast exposure on clinical neuropathology. Clearer understanding of the human neuropathology would enable validation of preclinical and computational models, which are attempting to simulate blast wave interactions with the central nervous system. Furthermore, the civilian experience with bTBI suggests that polytrauma models incorporating both brain and lung injuries may be more relevant to the study of civilian countermeasures than considering models with a neurological focus alone. PMID:20453776

  16. Traumatic brain injury caused by laser-induced shock wave in rats: a novel laboratory model for studying blast-induced traumatic brain injury

    NASA Astrophysics Data System (ADS)

    Hatano, Ben; Matsumoto, Yoshihisa; Otani, Naoki; Saitoh, Daizoh; Tokuno, Shinichi; Satoh, Yasushi; Nawashiro, Hiroshi; Matsushita, Yoshitaro; Sato, Shunichi

    2011-03-01

    The detailed mechanism of blast-induced traumatic brain injury (bTBI) has not been revealed yet. Thus, reliable laboratory animal models for bTBI are needed to investigate the possible diagnosis and treatment for bTBI. In this study, we used laser-induced shock wave (LISW) to induce TBI in rats and investigated the histopathological similarities to actual bTBI. After craniotomy, the rat brain was exposed to a single shot of LISW with a diameter of 3 mm at various laser fluences. At 24 h after LISW exposure, perfusion fixation was performed and the extracted brain was sectioned; the sections were stained with hematoxylin-eosin. Evans blue (EB) staining was also used to evaluate disruption of the blood brain barrier. At certain laser fluence levels, neural cell injury and hemorrhagic lesions were observed in the cortex and subcortical region. However, injury was limited in the tissue region that interacted with the LISW. The severity of injury increased with increasing laser fluence and hence peak pressure of the LISW. Fluorescence originating from EB was diffusively observed in the injuries at high fluence levels. Due to the grade and spatial controllability of injuries and the histological observations similar to those in actual bTBI, brain injuries caused by LISWs would be useful models to study bTBI.

  17. 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.

  18. 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.

  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. 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.

  1. Electronic non-adiabatic states: towards a density functional theory beyond the Born–Oppenheimer approximation

    PubMed Central

    Gidopoulos, Nikitas I.; Gross, E. K. U.

    2014-01-01

    A novel treatment of non-adiabatic couplings is proposed. The derivation is based on a theorem by Hunter stating that the wave function of the complete system of electrons and nuclei can be written, without approximation, as a Born–Oppenheimer (BO)-type product of a nuclear wave function, X(R), and an electronic one, ΦR(r), which depends parametrically on the nuclear configuration R. From the variational principle, we deduce formally exact equations for ΦR(r) and X(R). The algebraic structure of the exact nuclear equation coincides with the corresponding one in the adiabatic approximation. The electronic equation, however, contains terms not appearing in the adiabatic case, which couple the electronic and the nuclear wave functions and account for the electron–nuclear correlation beyond the BO level. It is proposed that these terms can be incorporated using an optimized local effective potential. PMID:24516183

  2. Comprehensive 3D Model of Shock Wave-Brain Interactions in Blast-Induced Traumatic Brain Injuries

    DTIC Science & Technology

    2009-10-01

    waves can cause brain damage by other mechanisms including excess pressure (leading to contusions), excess strain (leading to subdural ... hematomas and/or diffuse axonal injuries), and, in particular, cavitation effects (leading to subcellular damage). This project aims at the development of a

  3. 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.

  4. Non-adiabatic dynamics of molecules in optical cavities

    NASA Astrophysics Data System (ADS)

    Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul

    2016-02-01

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  5. Non-adiabatic dynamics of molecules in optical cavities

    SciTech Connect

    Kowalewski, Markus Bennett, Kochise; Mukamel, Shaul

    2016-02-07

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  6. 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.

  7. Cerebrospinal Fluid Chemokine (C-C Motif) Ligand 2 Is an Early-Response Biomarker for Blast-Overpressure-Wave-Induced Neurotrauma in Rats.

    PubMed

    Wang, Ying; Wei, Yanling; Oguntayo, Samuel; Wilder, Donna; Tong, Lawrence; Su, Yan; Gist, Irene; Arun, Peethambaran; Long, Joseph B

    2017-02-15

    Chemokines and their receptors are of great interest within the milieu of immune responses elicited in the central nervous system in response to trauma. Chemokine (C-C motif)) ligand 2 (CCL2), which is also known as monocyte chemotactic protein-1, has been implicated in the pathogenesis of traumatic brain injury (TBI), brain ischemia, Alzheimer's disease, and other neurodegenerative diseases. In this study, we investigated the time course of CCL2 accumulation in cerebrospinal fluid (CSF) after exposures to single and repeated blast overpressures of varied intensities along with the neuropathological changes and motor deficits resulting from these blast conditions. Significantly increased concentrations of CCL2 in CSF were evident by 1 h of blast exposure and persisted over 24 h with peak levels measured at 6 h post-injury. The increased levels of CCL2 in CSF corresponded with both the number and intensities of blast overpressure and were also commensurate with the extent of neuromotor impairment and neuropathological abnormalities resulting from these exposures. CCL2 levels in CSF and plasma were tightly correlated with levels of CCL2 messenger RNA in cerebellum, the brain region most consistently neuropathologically disrupted by blast. In view of the roles of CCL2 that have been implicated in multiple neurodegenerative disorders, it is likely that the sustained high levels of CCL2 and the increased expression of its main receptor, CCR2, in the brain after blast may similarly contribute to neurodegenerative processes after blast exposure. In addition, the markedly elevated concentration of CCL2 in CSF might be a candidate early-response biomarker for diagnosis and prognosis of blast-induced TBI.

  8. 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.

  9. The best of both Reps—Diabatized Gaussians on adiabatic surfaces

    NASA Astrophysics Data System (ADS)

    Meek, Garrett A.; Levine, Benjamin G.

    2016-11-01

    When simulating nonadiabatic molecular dynamics, choosing an electronic representation requires consideration of well-known trade-offs. The uniqueness and spatially local couplings of the adiabatic representation come at the expense of an electronic wave function that changes discontinuously with nuclear motion and associated singularities in the nonadiabatic coupling matrix elements. The quasi-diabatic representation offers a smoothly varying wave function and finite couplings, but identification of a globally well-behaved quasi-diabatic representation is a system-specific challenge. In this work, we introduce the diabatized Gaussians on adiabatic surfaces (DGAS) approximation, a variant of the ab initio multiple spawning (AIMS) method that preserves the advantages of both electronic representations while avoiding their respective pitfalls. The DGAS wave function is expanded in a basis of vibronic functions that are continuous in both electronic and nuclear coordinates, but potentially discontinuous in time. Because the time-dependent Schrödinger equation contains only first-order derivatives with respect to time, singularities in the second-derivative nonadiabatic coupling terms (i.e., diagonal Born-Oppenheimer correction; DBOC) at conical intersections are rigorously absent, though singular time-derivative couplings remain. Interpolation of the electronic wave function allows the accurate prediction of population transfer probabilities even in the presence of the remaining singularities. We compare DGAS calculations of the dynamics of photoexcited ethene to AIMS calculations performed in the adiabatic representation, including the DBOC. The 28 fs excited state lifetime observed in DGAS simulations is considerably shorter than the 50 fs lifetime observed in the adiabatic simulations. The slower decay in the adiabatic representation is attributable to the large, repulsive DBOC in the neighborhood of conical intersections. These repulsive DBOC terms are artifacts

  10. An interacting adiabatic quantum motor

    NASA Astrophysics Data System (ADS)

    Viola Kusminskiy, Silvia; Bruch, Anton; von Oppen, Felix

    We consider the effect of electron-electron interactions on the performance of an adiabatic quantum motor based on a Thouless pump operating in reverse. We model such a device by electrons in a 1d wire coupled to a slowly moving periodic potential associated with the classical mechanical degree of freedom of the motor. This periodic degree of freedom is set into motion by a bias voltage applied to the 1d electron channel. We investigate the Thouless motor with interacting leads modeled as Luttinger liquids. We show that interactions enhance the energy gap opened by the periodic potential and thus the robustness of the Thouless motor against variations in the chemical potential. We show that the motor degree of freedom can be described as a mobile impurity in a Luttinger liquid obeying Langevin dynamics with renormalized coefficients due to interactions, for which we give explicit expressions.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Effect of laser supported detonation wave confinement on termination conditions

    NASA Astrophysics Data System (ADS)

    Ushio, Masato; Komurasaki, Kimiya; Kawamura, Koichi; Arakawa, Yoshihiro

    2008-06-01

    A laser supported detonation (LSD) wave was driven using line-focusing laser optics, in which an induced blast wave expanded laterally from the LSD region to surrounding air in two-dimensional space. The LSD wave was confined in quasi-1D space using a wedge nozzle to restrict the lateral expansion of a blast wave. The LSD termination threshold and the blast wave energy were deduced from shadowgraphs showing the blast wave expansion. The respective threshold laser intensities for cases with and without confinement were estimated as 17 and 34 GW/m2, indicating that the lateral expansion strongly influenced on the LSD termination condition.

  18. 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.

  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 Quantum Search in Open Systems.

    PubMed

    Wild, Dominik S; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y; Lukin, Mikhail D

    2016-10-07

    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.

  1. 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.

  2. 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)

  3. 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.

  4. 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.

  5. Brain injuries from blast.

    PubMed

    Bass, Cameron R; Panzer, Matthew B; Rafaels, Karen A; Wood, Garrett; Shridharani, Jay; Capehart, Bruce

    2012-01-01

    Traumatic brain injury (TBI) from blast produces a number of conundrums. This review focuses on five fundamental questions including: (1) What are the physical correlates for blast TBI in humans? (2) Why is there limited evidence of traditional pulmonary injury from blast in current military field epidemiology? (3) What are the primary blast brain injury mechanisms in humans? (4) If TBI can present with clinical symptoms similar to those of Post-Traumatic Stress Disorder (PTSD), how do we clinically differentiate blast TBI from PTSD and other psychiatric conditions? (5) How do we scale experimental animal models to human response? The preponderance of the evidence from a combination of clinical practice and experimental models suggests that blast TBI from direct blast exposure occurs on the modern battlefield. Progress has been made in establishing injury risk functions in terms of blast overpressure time histories, and there is strong experimental evidence in animal models that mild brain injuries occur at blast intensities that are similar to the pulmonary injury threshold. Enhanced thoracic protection from ballistic protective body armor likely plays a role in the occurrence of blast TBI by preventing lung injuries at blast intensities that could cause TBI. Principal areas of uncertainty include the need for a more comprehensive injury assessment for mild blast injuries in humans, an improved understanding of blast TBI pathophysiology of blast TBI in animal models and humans, the relationship between clinical manifestations of PTSD and mild TBI from blunt or blast trauma including possible synergistic effects, and scaling between animals models and human exposure to blasts in wartime and terrorist attacks. Experimental methodologies, including location of the animal model relative to the shock or blast source, should be carefully designed to provide a realistic blast experiment with conditions comparable to blasts on humans. If traditional blast scaling is

  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. 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.

  8. Hydration and temperature development of concrete made with blast-furnace slag cement

    SciTech Connect

    Schutter, G. de

    1999-01-01

    In Europe, massive concrete elements often are made with blast-furnace slag cements. To better deal with the problem of early-age thermal cracking in these cases, a new hydration model for blast-furnace slag cements is developed, which is based on isothermal and adiabatic hydration tests. In the hydration model, the heat production rate is calculated as a function of the degree of hydration and the temperature. The accuracy of temperature simulations using this new hydration model is evaluated by tests on hardening massive concrete cylinders made with blast-furnace slag cement.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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)...

  14. 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...

  15. 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)...

  16. 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...

  17. 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)...

  18. 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...

  19. 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...

  20. 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)...

  1. Variation of Wave Action: Modulations of the Phase Shift for Strongly Nonlinear Dispersive Waves with Weak Dissipation. A New Adiabatic Invariant Involving the Modulated Phase Shift for Strongly Nonlinear, Slowly Varying, and Weakly Damped Oscillators. The Modulated Phase Shift for Weakly Dissipated Nonlinear Oscillatory Waves of the Korteweg-de Vries Type,

    DTIC Science & Technology

    1987-09-25

    for the Korteweg - deVries equation . In order to understand the effects of a slowly varying medium, Luke [1] in 1966 utilized themethod of multiple... Korteweg - deVries type equations [7]. For clarity, we note that after using (4.9) and VkJ : 0 [see (7.6)] the equation for the modulated phase shift O(X,T...dispersive oscillatory waves are analyzed for Korteweg - deVries type partial differential equations with slowly varying coefficients and arbitrary

  2. Adiabatic Phase Mixing and Fast Electron Heating in Thin current Sheet

    NASA Astrophysics Data System (ADS)

    Che, H.; Drake, J. F.; Swisdak, M. M.; Goldstein, M. L.

    2012-12-01

    Using particle-in-cell simulations and kinetic theory, it's found that strong Buneman instability develop non-linearly in thin current layer form in plasma with Ω e/ω pe< 1. The Buneman instability produces strong electric field and fast phase mixing which leads to the increase of electron temperature by more than a factor of 10 in a few tens of electron gyro-periods. The resonance of wave-particles feeds waves with particle's kinetic energy and causes the growth of waves and strong trapping of electrons at a large velocity range. We discovered it is the adiabatic movement of trapped electrons produce fast phase mixing when the particle's bounce rate is much larger than the growth and decay rate of waves. The adiabatic movement effectively exchange energy between particles and waves and redistribute the energy from high velocity electrons to low energy electrons with the assistance of the non-adiabatic crossing of separatrix of electron holes. The implications of the results for reconnection are being explored.

  3. 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.

  4. 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.

  5. 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.

  6. Understanding the Effects of Blast Wave on the Intracranial Pressure and Traumatic Brain Injury in Rodents and Humans Using Experimental Shock Tube and Numerical Simulations

    DTIC Science & Technology

    2014-07-01

    tube system, (b) realistic explosive surrogate (RED) head with hybrid III neck inside 28 in. shock tube, (c) head with hybrid III neck outside 9 in...Chapter 4 describes the experiments of the blast response of a surrogate head. the pressure-acceleration response of a head- neck human surrogate RED...the neck . The loading had an initial acceleration phase followed by deceleration. During both acceleration and deceleration phases, high shear

  7. Adiabatic optimization versus diffusion Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Jarret, Michael; Jordan, Stephen P.; Lackey, Brad

    2016-10-01

    Most experimental and theoretical studies of adiabatic optimization use stoquastic Hamiltonians, whose ground states are expressible using only real nonnegative amplitudes. This raises a question as to whether classical Monte Carlo methods can simulate stoquastic adiabatic algorithms with polynomial overhead. Here we analyze diffusion Monte Carlo algorithms. We argue that, based on differences between L1 and L2 normalized states, these algorithms suffer from certain obstructions preventing them from efficiently simulating stoquastic adiabatic evolution in generality. In practice however, we obtain good performance by introducing a method that we call Substochastic Monte Carlo. In fact, our simulations are good classical optimization algorithms in their own right, competitive with the best previously known heuristic solvers for MAX-k -SAT at k =2 ,3 ,4 .

  8. Nonadiabatic exchange dynamics during adiabatic frequency sweeps.

    PubMed

    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.

  9. 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.

  10. 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.

  11. On black hole spectroscopy via adiabatic invariance

    NASA Astrophysics Data System (ADS)

    Jiang, Qing-Quan; Han, Yan

    2012-12-01

    In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form Iadia = ∮pi dqi. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by ΔA = 8 π lp2 in the Schwarzschild and Painlevé coordinates.

  12. 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.

  13. 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.

  14. 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.

  15. Adiabatic cluster-state quantum computing

    SciTech Connect

    Bacon, Dave; Flammia, Steven T.

    2010-09-15

    Models of quantum computation (QC) are important because they change the physical requirements for achieving universal QC. For example, one-way QC requires the preparation of an entangled ''cluster'' state, followed by adaptive measurement on this state, a set of requirements which is different from the standard quantum-circuit model. Here we introduce a model based on one-way QC but without measurements (except for the final readout), instead using adiabatic deformation of a Hamiltonian whose initial ground state is the cluster state. Our results could help increase the feasibility of adiabatic schemes by using tools from one-way QC.

  16. Markovian quantum master equation beyond adiabatic regime.

    PubMed

    Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo

    2017-01-01

    By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.

  17. Markovian quantum master equation beyond adiabatic regime

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo

    2017-01-01

    By introducing a temporal change time scale τA(t ) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τA(t ) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.

  18. 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.

  19. Highly parallel implementation of non-adiabatic Ehrenfest molecular dynamics

    NASA Astrophysics Data System (ADS)

    Kanai, Yosuke; Schleife, Andre; Draeger, Erik; Anisimov, Victor; Correa, Alfredo

    2014-03-01

    While the adiabatic Born-Oppenheimer approximation tremendously lowers computational effort, many questions in modern physics, chemistry, and materials science require an explicit description of coupled non-adiabatic electron-ion dynamics. Electronic stopping, i.e. the energy transfer of a fast projectile atom to the electronic system of the target material, is a notorious example. We recently implemented real-time time-dependent density functional theory based on the plane-wave pseudopotential formalism in the Qbox/qb@ll codes. We demonstrate that explicit integration using a fourth-order Runge-Kutta scheme is very suitable for modern highly parallelized supercomputers. Applying the new implementation to systems with hundreds of atoms and thousands of electrons, we achieved excellent performance and scalability on a large number of nodes both on the BlueGene based ``Sequoia'' system at LLNL as well as the Cray architecture of ``Blue Waters'' at NCSA. As an example, we discuss our work on computing the electronic stopping power of aluminum and gold for hydrogen projectiles, showing an excellent agreement with experiment. These first-principles calculations allow us to gain important insight into the the fundamental physics of electronic stopping.

  20. Blast Technologies

    DTIC Science & Technology

    2011-06-27

    Development Generic Hull Testing Airbag and Sensor Technology Development Blast Data Recorder Specifications and Fielding Numerical Model Improvement...seat designs, airbag and restraint systems, and energy absorbing flooring solutions  Vehicle event data recorders for collecting highly accurate...treatments.  Airbag or comparable technologies such as bolsters.  Sensors that can detect and deploy/trigger interior treatments within the timeframe of a

  1. 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.

  2. The Effect of Underwater Blast on Aggregating Brain Cell Cultures.

    PubMed

    Sawyer, Thomas W; Lee, Julian J; Villanueva, Mercy; Wang, Yushan; Nelson, Peggy; Song, Yanfeng; Fan, Chengyang; Barnes, Julia; McLaws, Lori

    2017-01-15

    Although the deleterious effects of primary blast on gas-filled organs are well accepted, the effect of blast-induced shock waves on the brain is less clear because of factors that complicate the interpretation of clinical and experimental data. Brain cell aggregate cultures are comprised of multiple differentiated brain cell types and were used to examine the effects of underwater blast. Suspensions of these cultures encased in dialysis tubing were exposed to explosive-generated underwater blasts of low (∼300 kPa), medium (∼2,700 kPa), or high (∼14,000 kPa) intensities and harvested at 1-28 days post-exposure. No changes in gross morphology were noted immediately or weeks after blast wave exposure, and no increases in either apoptotic (caspase-3) or necrotic (lactate dehydrogenase) cell death were observed. Changes in neuronal (neurofilament H, acetylcholinesterase, and choline acetyltransferase) and glial (glial fibrillary acidic protein, glutamine synthetase) endpoints did not occur. However, significant time- and pressure-related increases in Akt (protein kinase B) phosphorylation were noted, as well as declines in vascular endothelial growth factor levels, implicating pathways involved in cellular survival mechanisms. The free-floating nature of the aggregates during blast wave exposure, coupled with their highly hydrolyzed dialysis tubing containment, results in minimized boundary effects, thus enabling accurate assessment of brain cell response to a simplified shock-induced stress wave. This work shows that, at its simplest, blast-induced shock waves produce subtle changes in brain tissue. This study has mechanistic implications for the study of primary blast-induced traumatic brain injury and supports the thesis that underwater blast may cause subtle changes in the brains of submerged individuals.

  3. 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

  4. 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)

  5. 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…

  6. 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.

  7. 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

  8. Adiabatic and Non-adiabatic quenches in a Spin-1 Bose Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Boguslawski, Matthew; Hebbe Madhusudhana, Bharath; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael

    2016-05-01

    A quantum phase transition (QPT) is observed in a wide range of phenomena. We have studied the dynamics of a spin-1 ferromagnetic Bose-Einstein condensate for both adiabatic and non-adiabatic quenches through a QPT. At the quantum critical point (QCP), finite size effects lead to a non-zero gap, which makes an adiabatic quench possible through the QPT. We experimentally demonstrate such a quench, which is forbidden at the mean field level. For faster quenches through the QCP, the vanishing energy gap causes the reaction timescale of the system to diverge, preventing the system from adiabatically following the ground state. We measure the temporal evolution of the spin populations for different quench speeds and determine the exponents characterizing the scaling of the onset of excitations, which are in good agreement with the predictions of Kibble-Zurek mechanism.

  9. 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.

  10. Fixed-point adiabatic quantum search

    NASA Astrophysics Data System (ADS)

    Dalzell, Alexander M.; Yoder, Theodore J.; Chuang, Isaac L.

    2017-01-01

    Fixed-point quantum search algorithms succeed at finding one of M target items among N total items even when the run time of the algorithm is longer than necessary. While the famous Grover's algorithm can search quadratically faster than a classical computer, it lacks the fixed-point property—the fraction of target items must be known precisely to know when to terminate the algorithm. Recently, Yoder, Low, and Chuang [Phys. Rev. Lett. 113, 210501 (2014), 10.1103/PhysRevLett.113.210501] gave an optimal gate-model search algorithm with the fixed-point property. Previously, it had been discovered by Roland and Cerf [Phys. Rev. A 65, 042308 (2002), 10.1103/PhysRevA.65.042308] that an adiabatic quantum algorithm, operating by continuously varying a Hamiltonian, can reproduce the quadratic speedup of gate-model Grover search. We ask, can an adiabatic algorithm also reproduce the fixed-point property? We show that the answer depends on what interpolation schedule is used, so as in the gate model, there are both fixed-point and non-fixed-point versions of adiabatic search, only some of which attain the quadratic quantum speedup. Guided by geometric intuition on the Bloch sphere, we rigorously justify our claims with an explicit upper bound on the error in the adiabatic approximation. We also show that the fixed-point adiabatic search algorithm can be simulated in the gate model with neither loss of the quadratic Grover speedup nor of the fixed-point property. Finally, we discuss natural uses of fixed-point algorithms such as preparation of a relatively prime state and oblivious amplitude amplification.

  11. Adiabatic burst evaporation from bicontinuous nanoporous membranes.

    PubMed

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk; Steinhart, Martin; Xue, Longjian

    2015-05-28

    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 10(7) μm(3) 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.

  12. Adiabatic circuits: converter for static CMOS signals

    NASA Astrophysics Data System (ADS)

    Fischer, J.; Amirante, E.; Bargagli-Stoffi, A.; Schmitt-Landsiedel, D.

    2003-05-01

    Ultra low power applications can take great advantages from adiabatic circuitry. In this technique a multiphase system is used which consists ideally of trapezoidal voltage signals. The input signals to be processed will often come from a function block realized in static CMOS. The static rectangular signals must be converted for the oscillating multiphase system of the adiabatic circuitry. This work shows how to convert the input signals to the proposed pulse form which is synchronized to the appropriate supply voltage. By means of adder structures designed for a 0.13µm technology in a 4-phase system there will be demonstrated, which additional circuits are necessary for the conversion. It must be taken into account whether the data arrive in parallel or serial form. Parallel data are all in one phase and therefore it is advantageous to use an adder structure with a proper input stage, e.g. a Carry Lookahead Adder (CLA). With a serial input stage it is possible to read and to process four signals during one cycle due to the adiabatic 4-phase system. Therefore input signals with a frequency four times higher than the adiabatic clock frequency can be used. This reduces the disadvantage of the slow clock period typical for adiabatic circuits. By means of an 8 bit Ripple Carry Adder (8 bit RCA) the serial reading will be introduced. If the word width is larger than 4 bits the word can be divided in 4 bit words which are processed in parallel. This is the most efficient way to minimize the number of input lines and pads. At the same time a high throughput is achieved.

  13. secureBLAST.

    PubMed

    Wiezer, Arnim; Merkl, Rainer

    2003-01-01

    secureBLAST supplements NCBI wwwblast with features necessary to control in an easy manageable way usage of BLAST data sets and their update. The concept we implemented allows to offer on a single BLAST server several data sets with individually configurable access rights. Security is provided by user authentication and encryption of the http traffic via SSL. By using secureBLAST, the administration of users and databases can be done via a web interface. Therefore, secureBLAST is valuable for institutions that have to restrict access to their datasets or just want to administer BLAST servers via a web interface.

  14. Modelling and Testing of Blast Effect On the Structures

    NASA Astrophysics Data System (ADS)

    Figuli, Lucia; Jangl, Štefan; Papán, Daniel

    2016-10-01

    As a blasting agent in the blasting and mining engineering, has been using one of so called new generation of explosives which offer greater flexibility in their range and application, and such explosive is ANFO. It is type of explosive consists of an oxidiser and a fuel (ammonium nitrate and fuel oil). One of such ANFO explosives which are industrially made in Slovakia is POLONIT. The explosive is a mixture of ammonium nitrate, methyl esters of higher fatty acids, vegetable oil and red dye. The paper deals with the analysis of structure subjected to the blast load created by the explosion of POLONIT charge. First part of paper is describing behaviour and characteristic of blast wave generated from the blast (detonation characteristics, physical characteristics, time-history diagram etc.) and the second part presents the behaviour of such loaded structures, because of the analysis of such dynamical loaded structure is required knowing the parameters of blast wave, its effect on structure and the tools for the solution of dynamic analysis. The real field tests of three different weight of charges and two different structures were done. The explosive POLONIT was used together with 25 g of ignition explosive PLNp10. Analytical and numerical model of blast loaded structure is compared with the results obtained from the field tests (is compared with the corresponding experimental accelerations). For the modelling structures were approximated as a one-degree system of freedom (SDOF), where the blast wave was estimated with linear decay and exponential decay using positive and negative phase of blast wave. Numerical solution of the steel beam dynamic response was performed via FEM (Finite Element Method) using standard software Visual FEA.

  15. 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

  16. Quantum-Classical Correspondence of Shortcuts to Adiabaticity

    NASA Astrophysics Data System (ADS)

    Okuyama, Manaka; Takahashi, Kazutaka

    2017-04-01

    We formulate the theory of shortcuts to adiabaticity in classical mechanics. For a reference Hamiltonian, the counterdiabatic term is constructed from the dispersionless Korteweg-de Vries (KdV) hierarchy. Then the adiabatic theorem holds exactly for an arbitrary choice of time-dependent parameters. We use the Hamilton-Jacobi theory to define the generalized action. The action is independent of the history of the parameters and is directly related to the adiabatic invariant. The dispersionless KdV hierarchy is obtained from the classical limit of the KdV hierarchy for the quantum shortcuts to adiabaticity. This correspondence suggests some relation between the quantum and classical adiabatic theorems.

  17. 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.

  18. Ramsey numbers and adiabatic quantum computing.

    PubMed

    Gaitan, Frank; Clark, Lane

    2012-01-06

    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. Comment on ``Adiabatic theory for the bipolaron''

    NASA Astrophysics Data System (ADS)

    Smondyrev, M. A.; Devreese, J. T.

    1996-05-01

    Comments are given on the application of the Bogoliubov-Tyablikov approach to the bipolaron problem in a recent paper by Lakhno [Phys. Rev. B 51, 3512 (1995)]. This author believes that his model (1) is the translation-invariant adiabatic theory of bipolarons and (2) gives asymptotically exact solutions in the adiabatic limit while the other approaches are considered as either phenomenological or variational in nature. Numerical results by Lakhno are in contradiction with all other papers published on the subject because his model leads to much lower energies. Thus, the author concludes that bipolarons ``are more stable than was considered before.'' We prove that both the analytical and the numerical results presented by Lakhno are wrong.

  20. 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.

  1. 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

  2. Fast forward to the classical adiabatic invariant

    NASA Astrophysics Data System (ADS)

    Jarzynski, Christopher; Deffner, Sebastian; Patra, Ayoti; Subaşı, Yiǧit

    2017-03-01

    We show how the classical action, an adiabatic invariant, can be preserved under nonadiabatic conditions. Specifically, for a time-dependent Hamiltonian H =p2/2 m +U (q ,t ) in one degree of freedom, and for an arbitrary choice of action I0, we construct a so-called fast-forward potential energy function VFF(q ,t ) that, when added to H , guides all trajectories with initial action I0 to end with the same value of action. We use this result to construct a local dynamical invariant J (q ,p ,t ) whose value remains constant along these trajectories. We illustrate our results with numerical simulations. Finally, we sketch how our classical results may be used to design approximate quantum shortcuts to adiabaticity.

  3. Adiabatic invariance with first integrals of motion.

    PubMed

    Adib, Artur B

    2002-10-01

    The construction of a microthermodynamic formalism for isolated systems based on the concept of adiabatic invariance is an old but seldom appreciated effort in the literature, dating back at least to P. Hertz [Ann. Phys. (Leipzig) 33, 225 (1910)]. An apparently independent extension of such formalism for systems bearing additional first integrals of motion was recently proposed by Hans H. Rugh [Phys. Rev. E 64, 055101 (2001)], establishing the concept of adiabatic invariance even in such singular cases. After some remarks in connection with the formalism pioneered by Hertz, it will be suggested that such an extension can incidentally explain the success of a dynamical method for computing the entropy of classical interacting fluids, at least in some potential applications where the presence of additional first integrals cannot be ignored.

  4. 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.

  5. 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.

  6. Multiphoton adiabatic passage for atom optics applications

    SciTech Connect

    Demeter, Gabor; Djotyan, Gagik P.

    2009-04-15

    We study the force exerted on two-level atoms by short, counterpropagating laser pulses. When the counterpropagating pulses overlap each other partially, multiphoton adiabatic processes are possible in several configurations, which amplify the force exerted on the atoms. We investigate the practical usefulness of such multiphoton adiabatic transitions for the manipulation of the atoms' mechanical state. In particular, we compare the efficiency of a pair of constant frequency, oppositely detuned laser pulses and that of a pair of frequency-chirped pulses. We also consider the case of prolonged exposure to a sequence of laser pulses for a duration that is comparable to or much larger than the spontaneous lifetime of the atoms. We use numerical methods to calculate the reduction of the force and the heating of the atomic ensemble when spontaneous emission cannot be neglected during the interaction. In addition, we derive simple approximate formulas for the force and the heating, and compare them to the numerical results.

  7. 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

  8. 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.

  9. Adiabatic Quantum Simulation of Quantum Chemistry

    PubMed Central

    Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán

    2014-01-01

    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. PMID:25308187

  10. Evaluation of Novel Polyunsaturated Fatty Acid Derived Lipid Mediators of Inflammation to Ameliorate the Deleterious Effects of Blast Overpressure on Eye and Brain Visual Processing Centers in Rats

    DTIC Science & Technology

    2013-10-01

    simulated blast overpressure waves the cellular, neuronal signaling, behavioral pathology of injuries to the eyes - specifically retina - and brain ...adult rat model of blast wave exposure, we rigorously characterized the cellular and functional damage to the eyes (retinas) and brain visual...strong relationship between the retina and brain optic tract cell damage (r = 0.8). Overall, our findings demonstrate that blast wave exposure leads

  11. Evaluation of Novel Polyunsaturated Fatty Acid Derived Lipid Mediators of Inflammation to Ameliorate the Deleterious Effects of Blast Overpressure on Eye and Brain Visual Processing Centers in Rats

    DTIC Science & Technology

    2014-10-01

    to high fidelity simulated blast over pressure waves (Friedlander waveform), as produced by a compressed air driven shock tube. Eye and brain ... brain , suggesting they have a rather limited potential as visual system therapeutics. 15. SUBJECT TERMS: Brain , eye, retina, blast wave , neuronal...face. It is also possible that the brain visual processing centers are being directly affected, since it is well established that blast wave exposure

  12. 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.

  13. Adiabatic charging of nickel-hydrogen batteries

    NASA Technical Reports Server (NTRS)

    Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna

    1995-01-01

    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.

  14. Aspects of adiabatic population transfer and control

    NASA Astrophysics Data System (ADS)

    Demirplak, Mustafa

    This thesis explores two different questions. The first question we answer is how to restore a given population transfer scenario given that it works efficiently in the adiabatic limit but fails because of lack of intensity and/or short duration. We derive a very simple algorithm to do this and apply it to both toy and realistic models. Two results emerge from this study. While the mathematical existence of the programme is certain it might not always be physically desirable. The restoration of adiabaticity is phase sensitive. The second question that is answered in this thesis is not how to invent new control paradigms, but rather what would happen to them in the presence of stochastic perturbers. We first use a phenomenological model to study the effect of stochastic dephasing on population transfer by stimulated Raman adiabatic passage. The results of this Monte Carlo calculation are qualitatively explained with a perturbation theoretical result in the dressed state basis. The reliability of our phenomenological model is questioned through a more rigorous hybrid quantal-classical simulation of controlled population transfer in HCl in Ar.

  15. Adiabatic graph-state quantum computation

    NASA Astrophysics Data System (ADS)

    Antonio, B.; Markham, D.; Anders, J.

    2014-11-01

    Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of \\dot{H} as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated.

  16. 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.

  17. An experimental investigation of blast driven turbulence

    NASA Astrophysics Data System (ADS)

    Musci, Benjamin; Ranjan, Devesh

    2016-11-01

    In the Georgia Tech Shock and Advanced Mixing Lab, a facility is being built to study blast driven turbulence. Motivated by the discrepancies observed between actual and modeled supernovae, this facility aims to resolve the important spatial scales in the extensive mixing of the outer layers. These outer layers will be modeled by subjecting two-three gases of varying density to a blast wave generated by Exploding Bridge Wires. The blast wave's interaction with perturbations at the gaseous, membrane-less, interfaces will induce the Richtmeyer-Meshkov or Rayleigh Taylor Instability, depending on the acceleration history and perturbation amplitude. Through the use of simultaneous Particle Image Velocimetry, and Planar Laser Induced Fluorescence, this project aims to determine the effect of interface initial conditions on turbulence. A 2D Diverging Wedge and 3D Diverging Conical Tube are being built to enable repeatable blast-wave production, continuous optical viewing of the flow, reproducible multi-layer interface creation, and the collection of simultaneous density-velocity measurements to directly measure turbulent quantities. The preliminary analysis informing the design of this facility, the construction progress, and updates on newly realized design constraints are presented.

  18. Blast and the Consequences on Traumatic Brain Injury-Multiscale Mechanical Modeling of Brain

    DTIC Science & Technology

    2011-02-17

    exposed to the Nahum head test scenarios. 4. Simulations under Blast Shock Waves Publication #s: [9], [10], [11], [41], [43] At many blast...the head model for three explosive scenarios[43]. Figure 8. Relative displacement-time histories for two clusters of a particular test with...Blasts, Brain Injury Professional, 2007;4(1), 10-15. [2] Naik , N. Abolfathi, G. Karami and M. Ziejewski, Micromechanical Viscoelastic

  19. 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.

  20. On the Validity of the Adiabatic Approximation in Compact Binary Inspirals

    NASA Astrophysics Data System (ADS)

    Maselli, Andrea; Gualtieri, Leonardo; Ferrari, Valeria; Pannarale, Francesco

    2015-01-01

    We use the post-Newtonian-Affine model to assess the validity of the adiabatic approximation in modeling tidal effects in the phase evolution of compact binary systems. We compute the dynamical evolution of the tidal tensor, which we estimate at the 2PN order, and of the quadrupole tensor, finding that their ratio, i.e. the tidal deformability, increases in the last phases of the inspiral. We derive the gravitational wave phase corrections due to this phenomenon and quantify how they affect gravitational wave detectability.

  1. A harmonic adiabatic approximation to calculate highly excited vibrational levels of ``floppy molecules''

    NASA Astrophysics Data System (ADS)

    Lauvergnat, David; Nauts, André; Justum, Yves; Chapuisat, Xavier

    2001-04-01

    The harmonic adiabatic approximation (HADA), an efficient and accurate quantum method to calculate highly excited vibrational levels of molecular systems, is presented. It is well-suited to applications to "floppy molecules" with a rather large number of atoms (N>3). A clever choice of internal coordinates naturally suggests their separation into active, slow, or large amplitude coordinates q', and inactive, fast, or small amplitude coordinates q″, which leads to an adiabatic (or Born-Oppenheimer-type) approximation (ADA), i.e., the total wave function is expressed as a product of active and inactive total wave functions. However, within the framework of the ADA, potential energy data concerning the inactive coordinates q″ are required. To reduce this need, a minimum energy domain (MED) is defined by minimizing the potential energy surface (PES) for each value of the active variables q', and a quadratic or harmonic expansion of the PES, based on the MED, is used (MED harmonic potential). In other words, the overall picture is that of a harmonic valley about the MED. In the case of only one active variable, we have a minimum energy path (MEP) and a MEP harmonic potential. The combination of the MED harmonic potential and the adiabatic approximation (harmonic adiabatic approximation: HADA) greatly reduces the size of the numerical computations, so that rather large molecules can be studied. In the present article however, the HADA is applied to our benchmark molecule HCN/CNH, to test the validity of the method. Thus, the HADA vibrational energy levels are compared and are in excellent agreement with the ADA calculations (adiabatic approximation with the full PES) of Light and Bačić [J. Chem. Phys. 87, 4008 (1987)]. Furthermore, the exact harmonic results (exact calculations without the adiabatic approximation but with the MEP harmonic potential) are compared to the exact calculations (without any sort of approximation). In addition, we compare the densities of

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Pathological Fingerprints, Systems Biology and Biomarkers of Blast Brain Injury

    DTIC Science & Technology

    2010-06-01

    stressors,including sheqar stress and blast wave. sICAM was measured in CSF and serum using SW ELISA and significantly accumulated in CSF and serum 24...metalloproteinases after different forms of blast. MMPs were measured using Quantibody arrays (Ray Biotech) and expressed as % of sham values (set as 100 %). Data...Neuron-Glia cell damage pathways. We measured CSF and serum levels of GFAP and UCHL-1, biomarkers of glia and neuron activation, respectively, after

  7. Head Kinematics Resulting from Simulated Blast Loading Scenarios

    DTIC Science & Technology

    2012-09-17

    pressure wave and the body which commonly damages air-filled organs such as the lungs , gastrointestinal tract, and ears. Secondary blast injury...subsequent impact with surrounding obstacles or the ground. Quaternary injury is the result of other factors including burns or inhalation of dust and gas... Woods , W., Feldman, S., Cummings, T., et al. (2011). Survival Risk Assessment for Primary Blast Exposures to the Head. Journal of neurotrauma, 2328

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. A new model for mild blast injury utilizing Drosophila melanogaster - biomed 2013.

    PubMed

    Hockey, K S; Hubbard, W B; Sajja, V S; Sholar, C A; Thorpe, C; Vandevord, P J; Rzigalinski, B A

    2013-01-01

    Current models for blast injury involve the use of mammalian species, which are costly and require extensive monitoring and housing, making it difficult to generate large numbers of injuries. The fruit fly, Drosophila melanogaster, has been utilized for many models of human disease including neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases. In this study, a model of blast injury was designed based on Drosophila, to provide a mechanism to investigate blast injury in large numbers and assess biochemical mechanisms of brain injury. Such studies may be used to identify specific pathways involved in blast-associated neurodegeneration, allowing more effective use of mammalian models. A custom-built blast wave simulator (ORA Inc.), comprised of a driver, test section, and wave eliminator, was used to create a blast wave. An acetate membrane was placed between the driver and the rectangular test section before compressed helium caused the membrane to rupture creating the blast wave. Membrane thickness correlates with the blast wave magnitude, which averaged 120 kPa for this experiment. Pressure sensors were inserted into the side of the tube in order to quantify the level of overpressure that the flies were exposed to. Five day old flies were held in a rectangular enclosed mesh fixture (10 flies per enclosure) which was placed in the center of the test section for blast delivery. Sham controls were exposed to same conditions with exception of blast. Lifespan and negative geotaxis, a measurement of motor function, was measured in flies after blast injury. Mild blast resulted in death of 28% of the flies. In surviving flies, motor function was initially reduced, but flies regained normal function by 8 days after injury. Although surviving flies regained normal motor function, flies subjected to mild blast died earlier than uninjured controls, with a 15.4% reduction in maximum lifespan and a 17% reduction in average lifespan, mimicking the scenario

  13. Non adiabatic electron behavior through a supercritical perpendicular collisionless shock: Impact of the shock front turbulence

    NASA Astrophysics Data System (ADS)

    Savoini, P.; Lembege, B.

    2010-11-01

    Adiabatic and nonadiabatic electrons transmitted through a supercritical perpendicular shock wave are analyzed with the help of test particle simulations based on field components issued from 2 - D full-particle simulation. A previous analysis (Savoini et al., 2005) based on 1 - D shock profile, including mainly a ramp (no apparent foot) and defined at a fixed time, has identified three distinct electron populations: adiabatic, overadiabatic, and underadiabatic, respectively, identified by μds/μus ≈ 1, >1 and <1, where μus and μds are the magnetic momenta in the upstream and downstream regions. Presently, this study is extended by investigating the impact of the time evolution of 2 - D shock front dynamics on these three populations. Analysis of individual time particle trajectories is performed and completed by statistics based on the use of different upstream velocity distributions (spherical shell of radius vshell and a Maxwellian with thermal velocity vthe). In all statistics, the three electron populations are clearly recovered. Two types of shock front nonstationarity are analyzed. First, the impact of the nonstationarity along the shock normal (due to the front self-reformation only) strongly depends on the values of vshell or vthe. For low values, the percentages of adiabatic and overadiabatic electrons are almost comparable but become anticorrelated under the filtering impact of the self-reformation; the percentage of the underadiabatic population remains almost unchanged. In contrast, for large values, this impact becomes negligible and the adiabatic population alone becomes dominant. Second, when 2 - D nonstationarity effects along the shock front (moving rippling) are fully included, all three populations are strongly diffused, leading to a larger heating; the overadiabatic population becomes largely dominant (and even larger than the adiabatic one) and mainly contributes to the energy spectrum.

  14. Constrained adiabatic trajectory method: a global integrator for explicitly time-dependent Hamiltonians.

    PubMed

    Leclerc, A; Jolicard, G; Viennot, D; Killingbeck, J P

    2012-01-07

    The constrained adiabatic trajectory method (CATM) is reexamined as an integrator for the Schrödinger equation. An initial discussion places the CATM in the context of the different integrators used in the literature for time-independent or explicitly time-dependent Hamiltonians. The emphasis is put on adiabatic processes and within this adiabatic framework the interdependence between the CATM, the wave operator, the Floquet, and the (t, t') theories is presented in detail. Two points are then more particularly analyzed and illustrated by a numerical calculation describing the H(2)(+) ion submitted to a laser pulse. The first point is the ability of the CATM to dilate the Hamiltonian spectrum and thus to make the perturbative treatment of the equations defining the wave function possible, possibly by using a Krylov subspace approach as a complement. The second point is the ability of the CATM to handle extremely complex time-dependencies, such as those which appear when interaction representations are used to integrate the system.

  15. 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.

  16. 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.

  17. Quantized adiabatic transport in momentum space.

    PubMed

    Ho, Derek Y H; Gong, Jiangbin

    2012-07-06

    Though topological aspects of energy bands are known to play a key role in quantum transport in solid-state systems, the implications of Floquet band topology for transport in momentum space (i.e., acceleration) have not been explored so far. Using a ratchet accelerator model inspired by existing cold-atom experiments, here we characterize a class of extended Floquet bands of one-dimensional driven quantum systems by Chern numbers, reveal topological phase transitions therein, and theoretically predict the quantization of adiabatic transport in momentum space. Numerical results confirm our theory and indicate the feasibility of experimental studies.

  18. Adiabatic demagnetization refrigerator for space use

    NASA Technical Reports Server (NTRS)

    Serlemitsos, A. T.; Warner, B. A.; Castles, S.; Breon, S. R.; San Sebastian, M.; Hait, T.

    1990-01-01

    An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determine the best design parameters for the gas gap heat switch, the new heat switch has a modular design and is easy to disassemble.

  19. Shortcuts to adiabaticity for quantum annealing

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazutaka

    2017-01-01

    We study the Ising Hamiltonian with a transverse field term to simulate the quantum annealing. Using shortcuts to adiabaticity, we design the time dependence of the Hamiltonian. The dynamical invariant is obtained by the mean-field ansatz, and the Hamiltonian is designed by the inverse engineering. We show that the time dependence of physical quantities such as the magnetization is independent of the speed of the Hamiltonian variation in the infinite-range model. We also show that rotating transverse magnetic fields are useful to achieve the ideal time evolution.

  20. Decoherence in a scalable adiabatic quantum computer

    SciTech Connect

    Ashhab, S.; Johansson, J. R.; Nori, Franco

    2006-11-15

    We consider the effects of decoherence on Landau-Zener crossings encountered in a large-scale adiabatic-quantum-computing setup. We analyze the dependence of the success probability--i.e., the probability for the system to end up in its new ground state--on the noise amplitude and correlation time. We determine the optimal sweep rate that is required to maximize the success probability. We then discuss the scaling of decoherence effects with increasing system size. We find that those effects can be important for large systems, even if they are small for each of the small building blocks.

  1. 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.

  2. 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.

  3. Combined Effects of Primary and Tertiary Blast on Rat Brain: Characterization of a Model of Blast-induced Mild Traumatic Brain Injury

    DTIC Science & Technology

    2014-03-01

    combat are exposed to a brain insult resulting from a combination of both a shock wave and biomechanical perturbation related to rapid acceleration...blast waves affect the brain along with diagnosing mbTBI are still a matter of considerable debate. The abovementioned caveats underline the...AD Award Number: W81XWH-11-2-0127 TITLE: Combined Effects of Primary and Tertiary Blast on Rat Brain : Characterization of a Model of

  4. Generating shortcuts to adiabaticity in quantum and classical dynamics

    NASA Astrophysics Data System (ADS)

    Jarzynski, Christopher

    2013-10-01

    Transitionless quantum driving achieves adiabatic evolution in a hurry, using a counterdiabatic Hamiltonian to stifle nonadiabatic transitions. Here this shortcut to adiabaticity is cast in terms of a generator of adiabatic transport. This yields a classical analog of transitionless driving, and provides a strategy for constructing quantal counterdiabatic Hamiltonians. As an application of this framework, exact classical and quantal counterdiabatic terms are obtained for a particle in a box and for even-power-law potentials in one degree of freedom.

  5. Injury risk prediction from computational simulations of ocular blast loading.

    PubMed

    Weaver, Ashley A; Stitzel, Sarah M; Stitzel, Joel D

    2017-04-01

    A predictive Lagrangian-Eulerian finite element eye model was used to analyze 2.27 and 0.45 kg trinitrotoluene equivalent blasts detonated from 24 different locations. Free air and ground level blasts were simulated directly in front of the eye and at lateral offset locations with box, average, less protective, and more protective orbital anthropometries, resulting in 96 simulations. Injury risk curves were developed for hyphema, lens dislocation, retinal damage, and globe rupture from experimental and computational data to compute risk from corneoscleral stress and intra-ocular pressure computational outputs. Corneoscleral stress, intra-ocular pressure, and injury risks increased when the blast size was larger and located nearer to the eye. Risks ranged from 20-100 % for hyphema, 1-100 % for lens dislocation, 2-100 % for retinal damage, and 0-98 % for globe rupture depending on the blast condition. Orbital geometry affected the stresses, pressures, and associated ocular injury risks of the blast conditions simulated. Orbital geometries that more fully surrounded the eye such as the more protective orbit tended to produce higher corneoscleral stresses and compression of the eye against the surrounding rigid orbit contributing to high stresses as the blast wave propagated. However, the more protective orbit tended to produce lower intra-ocular pressures in comparison with the other three orbital geometries which may indicate that the more protective orbit inhibits propagation of the blast wave and reduces ocular loading. Results of this parametric computational study of ocular blast loading are valuable to the design of eye protection equipment and the mitigation of blast-related eye injuries.

  6. Numerical simulations of solar spicules: Adiabatic and non-adiabatic studies

    NASA Astrophysics Data System (ADS)

    Kuźma, B.; Murawski, K.; Zaqarashvili, T. V.; Konkol, P.; Mignone, A.

    2017-01-01

    Aims: We aim to study the formation and evolution of solar spicules using numerical simulations of a vertical velocity pulse that is launched from the upper chromosphere. Methods: With the use of the PLUTO code, we numerically solved adiabatic and non-adiabatic magnetohydrodynamic (MHD) equations in 2D cylindrical geometry. We followed the evolution of spicules triggered by pulses that are launched in a vertical velocity component from the upper chromosphere. Then we compared the results obtained with and without non-adiabatic terms in the MHD equations. Results: Our numerical results reveal that the velocity pulse is steepened into a shock that propagates upward into the corona. The chromospheric cold and dense plasma follows the shock and rises into the corona with the mean speed of 20-25 km s-1. The nonlinear wake behind the pulse in the stratified atmosphere leads to quasi-periodic rebound shocks, which lead to quasi-periodic rising of chromospheric plasma into the corona with a period close to the acoustic cut-off period of the chromosphere. We found that the effect of non-adiabatic terms on spicule evolution is minor; the general properties of spicules such as their heights and rising-time remain slightly affected by these terms. Conclusions: In the framework of the axisymmetric model we devised, we show that the solar spicules can be triggered by the vertical velocity pulses, and thermal conduction and radiative cooling terms do not exert any significant influence on the dynamics of these spicules.

  7. Physical Processes of the Interaction Between Laser-Generated Plasma and Blast Wave Appearing in Laser-Driven In-Tube Accelerator Configuration

    SciTech Connect

    Sasoh, Akihiro; Mori, Koichi; Ohtani, Toshiro; Ohnishi, Naofumi; Ogino, Yosuke; Sawada, Keisuke

    2006-05-02

    Flow visualizations of the interaction between a laser-pulse-generated plasma and a shock wave driven by it have been experimentally conducted. The configuration of the experimental set-up corresponds to the laser-driven, in-tube accelerator. Primary-mode deformation of the plasma is governed by Richtmyer-Meshkov instability which is produced by the vector product between the pressure and density gradients, which in turn correspond to a reflected shock wave and to the plasma, respectively. Higher-mode contact surface deformations are supposedly originated in Rayleigh-Taylor instability in the shrinkage phase of the plasma, and is enhanced due to the passage of the reflected shock wave.

  8. On the Role of Prior Probability in Adiabatic Quantum Algorithms

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Lu, Songfeng; Yang, Liping

    2016-03-01

    In this paper, we study the role of prior probability on the efficiency of quantum local adiabatic search algorithm. The following aspects for prior probability are found here: firstly, only the probabilities of marked states affect the running time of the adiabatic evolution; secondly, the prior probability can be used for improving the efficiency of the adiabatic algorithm; thirdly, like the usual quantum adiabatic evolution, the running time for the case of multiple solution states where the number of marked elements are smaller enough than the size of the set assigned that contains them can be significantly bigger than that of the case where the assigned set only contains all the marked states.

  9. Adiabatic following for a three-state quantum system

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Shore, Bruce W.; Rangelov, Andon; Kyoseva, Elica

    2017-01-01

    Adiabatic time-evolution - found in various forms of adiabatic following and adiabatic passage - is often advantageous for controlled manipulation of quantum systems due to its insensitivity to deviations in the pulse shapes and timings. In this paper we discuss controlled adiabatic evolution of a three-state quantum system, a natural advance to the widespread use of two-state systems in numerous contemporary applications. We discuss, and illustrate, not only possibilities for population transfer but also for creating, with prescribed relative phase, 50:50 superpositions of two Zeeman sublevels in a letter-vee coupling linkage.

  10. Adiabatic approximation via hodograph translation and zero-curvature equations

    NASA Astrophysics Data System (ADS)

    Karasev, M. V.

    2014-04-01

    For quantum as well classical slow-fast systems, we develop a general method which allows one to compute the adiabatic invariant (approximate integral of motion), its symmetries, the adiabatic guiding center coordinates and the effective scalar Hamiltonian in all orders of a small parameter. The scheme does not exploit eigenvectors or diagonalization, but is based on the ideas of isospectral deformation and zero-curvature equations, where the role of "time" is played by the adiabatic (quantization) parameter. The algorithm includes the construction of the zero-curvature adiabatic connection and its splitting generated by averaging up to an arbitrary order in the small parameter.

  11. Quantum Adiabatic Algorithms and Large Spin Tunnelling

    NASA Technical Reports Server (NTRS)

    Boulatov, A.; Smelyanskiy, V. N.

    2003-01-01

    We provide a theoretical study of the quantum adiabatic evolution algorithm with different evolution paths proposed in this paper. The algorithm is applied to a random binary optimization problem (a version of the 3-Satisfiability problem) where the n-bit cost function is symmetric with respect to the permutation of individual bits. The evolution paths are produced, using the generic control Hamiltonians H (r) that preserve the bit symmetry of the underlying optimization problem. In the case where the ground state of H(0) coincides with the totally-symmetric state of an n-qubit system the algorithm dynamics is completely described in terms of the motion of a spin-n/2. We show that different control Hamiltonians can be parameterized by a set of independent parameters that are expansion coefficients of H (r) in a certain universal set of operators. Only one of these operators can be responsible for avoiding the tunnelling in the spin-n/2 system during the quantum adiabatic algorithm. We show that it is possible to select a coefficient for this operator that guarantees a polynomial complexity of the algorithm for all problem instances. We show that a successful evolution path of the algorithm always corresponds to the trajectory of a classical spin-n/2 and provide a complete characterization of such paths.

  12. The genesis of adiabatic shear bands

    PubMed Central

    Landau, P.; Osovski, S.; Venkert, A.; Gärtnerová, V.; Rittel, D.

    2016-01-01

    Adiabatic shear banding (ASB) is a unique dynamic failure mechanism that results in an unpredicted catastrophic failure due to a concentrated shear deformation mode. It is universally considered as a material or structural instability and as such, ASB is hardly controllable or predictable to some extent. ASB is modeled on the premise of stability analyses. The leading paradigm is that a competition between strain (rate) hardening and thermal softening determines the onset of the failure. It was recently shown that microstructural softening transformations, such as dynamic recrystallization, are responsible for adiabatic shear failure. These are dictated by the stored energy of cold work, so that energy considerations can be used to macroscopically model the failure mechanism. The initial mechanisms that lead to final failure are still unknown, as well as the ASB formation mechanism(s). Most of all - is ASB an abrupt instability or rather a gradual transition as would be dictated by microstructural evolutions? This paper reports thorough microstructural characterizations that clearly show the gradual character of the phenomenon, best described as a nucleation and growth failure mechanism, and not as an abrupt instability as previously thought. These observations are coupled to a simple numerical model that illustrates them. PMID:27849023

  13. Accurate Variational Description of Adiabatic Quantum Optimization

    NASA Astrophysics Data System (ADS)

    Carleo, Giuseppe; Bauer, Bela; Troyer, Matthias

    Adiabatic quantum optimization (AQO) is a quantum computing protocol where a system is driven by a time-dependent Hamiltonian. The initial Hamiltonian has an easily prepared ground-state and the final Hamiltonian encodes some desired optimization problem. An adiabatic time evolution then yields a solution to the optimization problem. Several challenges emerge in the theoretical description of this protocol: on one hand, the exact simulation of quantum dynamics is exponentially complex in the size of the optimization problem. On the other hand, approximate approaches such as tensor network states (TNS) are limited to small instances by the amount of entanglement that can be encoded. I will present here an extension of the time-dependent Variational Monte Carlo approach to problems in AQO. This approach is based on a general class of (Jastrow-Feenberg) entangled states, whose parameters are evolved in time according to a stochastic variational principle. We demonstrate this approach for optimization problems of the Ising spin-glass type. A very good accuracy is achieved when compared to exact time-dependent TNS on small instances. We then apply this approach to larger problems, and discuss the efficiency of the quantum annealing scheme in comparison with its classical counterpart.

  14. Nonadiabatic Transitions in Adiabatic Rapid Passage

    NASA Astrophysics Data System (ADS)

    Lu, T.; Miao, X.; Metcalf, H.

    2006-05-01

    Optical forces much larger than the ordinary radiative force can be achieved on a two-level atom by multiple repetitions of adiabatic rapid passage sweeps with counterpropagating light beams. Chirped light pulses drive the atom-laser system up a ladder of dressed state energy sheets on sequential trajectories, thereby decreasing the atomic kinetic energy. Nonadiabatic transitions between the energy sheets must be avoided for this process to be effective. We have calculated the nonadiabatic transition probability for various chirped light pulses numerically. These results were compared to the first Demkov-Kunike model and the well-known Landau-Zener model. In addition, an analytical form of the nonadiabatic transition probability has been found for linearly chirped pulses and an approximate form for generic symmetric finite-time pulses has been found for the entire parameter space using the technique of unitary integration. From this, the asymptotic transition probability in the adiabatic limit was derived. T. Lu, X. Miao, and H. Metcalf, Phys., Rev. A 71 061405(R) (2005). Yu. Demkov and M. Kunike, Vestn. Leningr. Univ. Fis. Khim., 16, 39 (1969); K.-A. Suominen and B. Garraway, Phys. Rev. A45, 374 (1992)

  15. Non-adiabatic Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Canfield, Jesse; Denissen, Nicholas; Reisner, Jon

    2016-11-01

    Onset of Rayleigh-Taylor instability (RTI) in a non-adiabatic environment is investigated with the multi-physics numerical model, FLAG. This work was inspired by laboratory experiments of non-adiabatic RTI, where a glass vessel with a layer of tetrahyrdofuran (THF) below a layer of toluene was placed inside a microwave. THF, a polar solvent, readily absorbs electromagnetic energy from microwaves. Toluene, a non-polar solvent, is nearly transparent to microwave heating. The presence of a heat source in the THF layer produced convection and a time-dependent Atwood number (At). The system, initially in stable hydrostatic equilibrium At < 0 , was set into motion by microwave induced, volumetric heating of the THF. The point when At > 0 , indicates that the system is RTI unstable. The observed dominant mode at the onset of RTI was the horizontal length scale of the vessel. This scale is contrary to classical RTI, where the modes start small and increases in scale with time. It is shown that the dominant RTI mode observed in the experiments was determined by the THF length scale prior to RTI. The dominant length scale transitions from the THF to the toluene via the updrafts and downdrafts in the convective cells. This happens when At passes from negative to positive. This work was funded by the Advanced Simulation and Computing Program.

  16. Moreton Waves

    NASA Technical Reports Server (NTRS)

    Thompson, B. J.

    1999-01-01

    "Moreton waves," named for the observer who popularized them, are a solar phenomenon also known in scientific literature as "Moreton-Ramsey wave," "flare waves," "flare-associated waves," "MHD blast waves," "chromospheric shock fronts" and various other combinations of terms which connote violently propagating impulsive disturbances. It is unclear whether all of the observations to which these terms have been applied pertain to a single physical phenomenon: there has perhaps been some overlap between the observations and the assumed physical properties of the observed occurrence. Moreton waves are ideally observed in the wings of H alpha, and appear as semi-circular fronts propagating at speeds ranging from several hundred to over a thousand km/sec. They form an arc, or "brow shape" which can span up to 180 degrees. Extrapolating the speed and locations of the arc indicates that the phenomenon's origin intersects well with the impulsive phase of the associated H alpha flare (if the flare exhibits an impulsive phase). However, the arc may not form or may not be observable until it is tens of megameters from the flaring region, and subsequently can propagate to distances exceeding 100 megameters. The high speeds and distances of propagation, plus the associated radio and energetic particle observations, provided strong evidence of a coronal, rather than a chromospheric origin. The H alpha manifestation of the wave is assumed to be the "ground track" or "skirt" of a three-dimensional disturbance.

  17. Three-Body Coulomb Functions in the Hyperspherical Adiabatic Expansion Method

    NASA Astrophysics Data System (ADS)

    Garrido, E.; Kievsky, A.; Viviani, M.

    2016-12-01

    In this work we describe a numerical method devised to compute continuum three-body wave functions. The method is implemented using the hyperspherical adiabatic expansion for the three-body wave function imposing a box boundary condition. The continuum energy spectrum results discretized and, for specific quantum number values, all the possible incoming and outgoing channels are simultaneously computed. For a given energy, the hyperradial continuum functions form a matrix whose ij-term refers to specific incoming and outgoing channels. When applied to three-body systems interacting only through the Coulomb potential, this method provides the adiabatic representation of the regular three-body Coulomb wave function. The computation of the irregular Coulomb wave function representation is also discussed. These regular and irregular Coulomb functions can be used to extract the S-matrix for those reactions where, together with some short-range potential, the Coulomb interaction is also present. The method is illustrated in the case of the 3→ 3 process of three alpha particles.

  18. Spectrum of abdominal organ injury in a primary blast type

    PubMed Central

    2009-01-01

    Introduction Abdominal organ injury in a primary blast type is always challenging for diagnosis. Air containing abdominal viscera is most vulnerable to effects of primary blast injury. In any patient exposed to a primary blast wave who presents with an acute abdomen, an abdominal organ injury is to be kept in a clinical suspicion. Aim Study various abdominal organ injuries occurring in a primary type of blast injury. Material and methods: All those who had exploratory laparotomy for abdominal organ injuries after a primary blast injury for a period of 10 years from January 1998 - January 2008 were included in this retrospective study. Results Total 154 patients had laparotomy for abdominal organ injuries with a primary blast type of injury. Small intestine was damaged in 48 patients (31.1%) followed by spleen in 22.7% cases. 54 patients (35.06%) had more than one organ injured. Liver laceration was present in 30 patients (19.48%). Multiple small gut perforations were present in 37 patients (77.08%). Negative laparotomy was found in 5 patients (3.24%) whereas 3 (1.94%) had re-exploration. Mortality was present in 6 patients (3.89%). Conclusions Primary blast injury causes varied abdominal organ injuries. Single or multiple organ damage can be there. Small intestine is commonest viscera injured. Laparotomy gives final diagnosis. PMID:20025766

  19. General view of blast furnace plant, with blast furnace "A" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of blast furnace plant, with blast furnace "A" (built in 1907) to the left; in the foreground is the turbo-blower and blast furnace gas-powered electric generating station (built in 1919), looking northwest - Bethlehem Steel Corporation, South Bethlehem Works, Blast Furnace "A", Along Lehigh River, North of Fourth Street, West of Minsi Trail Bridge, Bethlehem, Northampton County, PA

  20. A Phased Array Approach to Rock Blasting

    SciTech Connect

    Leslie Gertsch; Jason Baird

    2006-07-01

    A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

  1. Blast injury research models

    PubMed Central

    Kirkman, E.; Watts, S.; Cooper, G.

    2011-01-01

    Blast injuries are an increasing problem in both military and civilian practice. Primary blast injury to the lungs (blast lung) is found in a clinically significant proportion of casualties from explosions even in an open environment, and in a high proportion of severely injured casualties following explosions in confined spaces. Blast casualties also commonly suffer secondary and tertiary blast injuries resulting in significant blood loss. The presence of hypoxaemia owing to blast lung complicates the process of fluid resuscitation. Consequently, prolonged hypotensive resuscitation was found to be incompatible with survival after combined blast lung and haemorrhage. This article describes studies addressing new forward resuscitation strategies involving a hybrid blood pressure profile (initially hypotensive followed later by normotensive resuscitation) and the use of supplemental oxygen to increase survival and reduce physiological deterioration during prolonged resuscitation. Surprisingly, hypertonic saline dextran was found to be inferior to normal saline after combined blast injury and haemorrhage. New strategies have therefore been developed to address the needs of blast-injured casualties and are likely to be particularly useful under circumstances of enforced delayed evacuation to surgical care. PMID:21149352

  2. A Modified Adiabatic Quantum Algorithm for Evaluation of Boolean Functions

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Lu, Songfeng; Liu, Fang

    2015-09-01

    In this paper, we propose a modified construction of the quantum adiabatic algorithm for Boolean functions studied by M. Andrecut et al. [13, 14]. Our algorithm has the time complexity O(1) for the evaluation of Boolean functions, without additional computational cost of implementing the driving Hamiltonian, which is required by the adiabatic evolution described in [13, 14].

  3. Adiabat-shaping in indirect drive inertial confinement fusion

    SciTech Connect

    Baker, K. L.; Robey, H. F.; Milovich, J. L.; Jones, O. S.; Smalyuk, V. A.; Casey, D. T.; MacPhee, A. G.; Pak, A.; Celliers, P. M.; Clark, D. S.; Landen, O. L.; Peterson, J. L.; Berzak-Hopkins, L. F.; Weber, C. R.; Haan, S. W.; Döppner, T. D.; Dixit, S.; Hamza, A. V.; Jancaitis, K. S.; Kroll, J. J.; and others

    2015-05-15

    Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.

  4. The Adiabatic Invariance of the Action Variable in Classical Dynamics

    ERIC Educational Resources Information Center

    Wells, Clive G.; Siklos, Stephen T. C.

    2007-01-01

    We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of…

  5. Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.

    ERIC Educational Resources Information Center

    Sobel, Michael I.

    1980-01-01

    Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)

  6. Hybrid S2/Carbon Epoxy Composite Armours Under Blast Loads

    NASA Astrophysics Data System (ADS)

    Dolce, F.; Meo, Michele; Wright, A.; French, M.; Bernabei, M.

    2012-06-01

    Civil and military structures, such as helicopters, aircrafts, naval ships, tanks or buildings are susceptible to blast loads as terroristic attacks increases, therefore there is the need to design blast resistant structures. During an explosion the peak pressure produced by shock wave is much greater than the static collapse pressure. Metallic structures usually undergo large plastic deformations absorbing blast energy before reaching equilibrium. Due to their high specific properties, fibre-reinforced polymers are being considered for energy absorption applications in blast resistant armours. A deep insight into the relationship between explosion loads, composite architecture and deformation/fracture behaviour will offer the possibility to design structures with significantly enhanced energy absorption and blast resistance performance. This study presents the results of a numerical investigation aimed at understanding the performance of a hybrid composite (glass/carbon fibre) plate subjected to blast loads using commercial LS-DYNA software. In particular, the paper deals with numerical 3D simulations of damages caused by air blast waves generated by C4 charges on two fully clamped rectangular plates made of steel and hybrid (S2/Carbon) composite, respectively. A Multi Materials Arbitrary Lagrangian Eulerian (MMALE) formulation was used to simulate the shock phenomenon. For the steel plates, the Johnson-Cook material model was employed. For the composite plates both in-plane and out-of-plane failure criteria were employed. In particular, a contact tiebreak formulation with a mixed mode failure criteria was employed to simulate delamination failure. As for the steel plates the results showed that excellent correlation with the experimental data for the two blast load conditions in terms of dynamic and residual deflection for two different C4 charges. For the composite plates the numerical results showed that, as expected, a wider delamination damage was observed

  7. Military Traumatic Brain Injury and Blast

    DTIC Science & Technology

    2010-01-01

    cations compared to other mechanisms of injury such as acceleration -deceleration impact has become an im- portant question in the care of our service...injury. The above concepts lead to a frame of reference debate in relation to blast induced concussion or mTBI sug- gesting that lethal injury would...results in a 3D complex flow field that is altered by ambient conditions and envi- ronmental boundaries. This may result in multiple wave reflections and

  8. Blast overpressure after tire explosion: a fatal case.

    PubMed

    Pomara, Cristoforo; D'Errico, Stefano; Riezzo, Irene; Perilli, Gabriela; Volpe, Umberto; Fineschi, Vittorio

    2013-12-01

    Fatal blast injuries are generally reported in literature as a consequence of the detonation of explosives in war settings. The pattern of lesion depends on the position of the victim in relation to the explosion, on whether the blast tracks through air or water, and whether it happens in the open air or within an enclosed space and the distance from the explosion. Tire explosion-related injuries are rarely reported in literature. This study presents a fatal case of blast overpressure due to the accidental explosion of a truck tire occurring in a tire repair shop. A multidisciplinary approach to the fatality involving forensic pathologists and engineers revealed that the accidental explosion, which caused a series of primary and tertiary blast wave injuries, was due to tire deterioration.

  9. Quantum Adiabatic Optimization and Combinatorial Landscapes

    NASA Technical Reports Server (NTRS)

    Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.

    2003-01-01

    In this paper we analyze the performance of the Quantum Adiabatic Evolution (QAE) algorithm on a variant of Satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, gamma = M / N. We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (verses only energy) is used, and are able to show the existence of a dynamic threshold gamma = gammad, beyond which QAE should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz.

  10. Number Partitioning via Quantum Adiabatic Computation

    NASA Technical Reports Server (NTRS)

    Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)

    2002-01-01

    We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.

  11. The HAWC and SAFIRE Adiabatic Demagnetization Refrigerators

    NASA Technical Reports Server (NTRS)

    Tuttle, Jim; Shirron, Peter; DiPirro, Michael; Jackson, Michael; Behr, Jason; Kunes, Evan; Hait, Tom; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The High-Resolution Airborne Wide-band Camera (HAWC) and Submillimeter and Far Infrared Experiment (SAFIRE) are far-infrared experiments which will fly on the Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft. HAWC's detectors will operate at 0.2 Kelvin, while those of SAFIRE will be at 0.1 Kelvin. Each instrument will include an adiabatic demagnetization refrigerator (ADR) to cool its detector stage from the liquid helium bath temperature (HAWC's at 4.2 Kelvin and SAFIRE's pumped to about 1.3 Kelvin) to its operating temperature. Except for the magnets used to achieve the cooling and a slight difference in the heat switch design, the two ADRs are nearly identical. We describe the ADR design and present the results of performance testing.

  12. Sliding seal materials for adiabatic engines

    NASA Technical Reports Server (NTRS)

    Lankford, J.

    1985-01-01

    The sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, loading conditions that are representative of the adiabatic engine environment. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Microhardness tests were performed on the candidate materials at elevated temperatures, and in atmospheres relevant to the piston seal application, and optical and electron microscopy were used to elucidate the micromechanisms of wear following wear testing. X-ray spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Electrical effects in the friction and wear processes were explored in order to evaluate the potential usefulness of such effects in modifying the friction and wear rates in service. However, this factor was found to be of negligible significance in controlling friction and wear.

  13. An adiabatic demagnetization refrigerator for SIRTF

    NASA Astrophysics Data System (ADS)

    Timbie, P. T.; Bernstein, G. M.; Richards, P. L.

    1989-02-01

    An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.

  14. Design of a spaceworthy adiabatic demagnetization refrigerator

    NASA Astrophysics Data System (ADS)

    Serlemitsos, A. T.; Kunes, E.; Sansebastian, M.

    A spaceworthy adiabatic demagnetization refrigerator (ADR) under development at NASA-Goddard is presented. A baseline model heat switch was tested extensively with an on/off ratio of about 10,000 and a parasitic heat leak of 10 micro-W. Data obtained from the breadboard models were used to design an ADR with improved structural integrity. The core of the ADR is the salt pill which consists of the paramagnetic salt crystal and the thermal bus. When a magnetic field is applied to the salt it forces the alignment of the magnetic moments, thereby decreasing the entropy of the salt. Preliminary tests results showed a net crystal mass of 680 g instead of the expected 740 g, which indicate that there are gaps in the salt pill. A partial fix was accomplished by sealing helium gas in the salt pill at a pressure of 2 bar, which improved the thermal contact during salt magnetization, at about 2 K.

  15. On stress collapse in adiabatic shear bands

    NASA Astrophysics Data System (ADS)

    Wright, T. W.; Walter, J. W.

    T HE DYNAMICS of adiabatic shear band formation is considered making use of a simplified thermo/visco/plastic flow law. A new numerical solution is used to follow the growth of a perturbation from initiation, through early growth and severe localization, to a slowly varying terminal configuration. Asymptotic analyses predict the early and late stage patterns, but the timing and structure of the abrupt transition to severe localization can only be studied numerically, to date. A characteristic feature of the process is that temperature and plastic strain rate begin to localize immediately, but only slowly, whereas the stress first evolves almost as if there were no perturbation, but then collapses rapidly when severe localization occurs.

  16. Index Theory and Adiabatic Limit in QFT

    NASA Astrophysics Data System (ADS)

    Wawrzycki, Jarosław

    2013-08-01

    The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: (1) local algebraic formulation of Haag, (2) Wightman formulation and (3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between (1) and (3) and utilize the known relationships between (1) and (2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit ( confinement problem in the phenomenological standard model approach). We extend the method of deformation of Dütsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index—an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.

  17. An adiabatic demagnetization refrigerator for SIRTF

    NASA Technical Reports Server (NTRS)

    Timbie, P. T.; Bernstein, G. M.; Richards, P. L.

    1989-01-01

    An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.

  18. Design of a spaceworthy adiabatic demagnetization refrigerator

    NASA Technical Reports Server (NTRS)

    Serlemitsos, A. T.; Kunes, E.; Sansebastian, M.

    1992-01-01

    A spaceworthy adiabatic demagnetization refrigerator (ADR) under development at NASA-Goddard is presented. A baseline model heat switch was tested extensively with an on/off ratio of about 10,000 and a parasitic heat leak of 10 micro-W. Data obtained from the breadboard models were used to design an ADR with improved structural integrity. The core of the ADR is the salt pill which consists of the paramagnetic salt crystal and the thermal bus. When a magnetic field is applied to the salt it forces the alignment of the magnetic moments, thereby decreasing the entropy of the salt. Preliminary tests results showed a net crystal mass of 680 g instead of the expected 740 g, which indicate that there are gaps in the salt pill. A partial fix was accomplished by sealing helium gas in the salt pill at a pressure of 2 bar, which improved the thermal contact during salt magnetization, at about 2 K.

  19. Adiabatic connection at negative coupling strengths

    SciTech Connect

    Seidl, Michael; Gori-Giorgi, Paola

    2010-01-15

    The adiabatic connection of density functional theory (DFT) for electronic systems is generalized here to negative values of the coupling strength alpha (with attractive electrons). In the extreme limit alpha->-infinity a simple physical solution is presented and its implications for DFT (as well as its limitations) are discussed. For two-electron systems (a case in which the present solution can be calculated exactly), we find that an interpolation between the limit alpha->-infinity and the opposite limit of infinitely strong repulsion (alpha->+infinity) yields a rather accurate estimate of the second-order correlation energy E{sub c}{sup GL2}[rho] for several different densities rho, without using virtual orbitals. The same procedure is also applied to the Be isoelectronic series, analyzing the effects of near degeneracy.

  20. Adiabatic theory for anisotropic cold molecule collisions

    SciTech Connect

    Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod

    2015-08-21

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.

  1. An Integrated Development Environment for Adiabatic Quantum Programming

    SciTech Connect

    Humble, Travis S; McCaskey, Alex; Bennink, Ryan S; Billings, Jay Jay; D'Azevedo, Eduardo; Sullivan, Blair D; Klymko, Christine F; Seddiqi, Hadayat

    2014-01-01

    Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware raises the question of how well quantum programs perform. Benchmarking behavior is challenging since the multiple steps to synthesize an adiabatic quantum program are highly tunable. We present an adiabatic quantum programming environment called JADE that provides control over all the steps taken during program development. JADE captures the workflow needed to rigorously benchmark performance while also allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its use for benchmarking adiabatic quantum programs.

  2. An integrated programming and development environment for adiabatic quantum optimization

    NASA Astrophysics Data System (ADS)

    Humble, T. S.; McCaskey, A. J.; Bennink, R. S.; Billings, J. J.; DʼAzevedo, E. F.; Sullivan, B. D.; Klymko, C. F.; Seddiqi, H.

    2014-01-01

    Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization (AQO) programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for AQO called Jade Adiabatic Development Environment (JADE) that provides control over all the steps taken during program synthesis. JADE captures the workflow needed to rigorously specify the AQO algorithm while allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its potential use for benchmarking AQO programs by the quantum computer science community.

  3. Adiabatic theory, Liapunov exponents, and rotation number for quadratic Hamiltonians

    NASA Astrophysics Data System (ADS)

    Delyon, François; Foulon, Patrick

    1987-11-01

    We consider the adiabatic problem for general time-dependent quadratic Hamiltonians and develop a method quite different from WKB. In particular, we apply our results to the Schrödinger equation in a strip. We show that there exists a first regular step (avoiding resonance problems) providing one adiabatic invariant, bounds on the Liapunov exponents, and estimates on the rotation number at any order of the perturbation theory. The further step is shown to be equivalent to a quantum adiabatic problem, which, by the usual adiabatic techniques, provides the other possible adiabatic invariants. In the special case of the Schrödinger equation our method is simpler and more powerful than the WKB techniques.

  4. Adiabatic vs. non-adiabatic determination of specific absorption rate of ferrofluids

    NASA Astrophysics Data System (ADS)

    Natividad, Eva; Castro, Miguel; Mediano, Arturo

    2009-05-01

    The measurement of temperature variations in adiabatic conditions allows the determination of the specific absorption rate of magnetic nanoparticles and ferrofluids from the correct incremental expression, SAR=(1/ m MNP) C(Δ T/Δ t). However, when measurements take place in non-adiabatic conditions, one must approximate this expression by SAR≈ Cβ/ m MNP, where β is the initial slope of the temperature vs. time curve during alternating field application. The errors arising from the use of this approximation were estimated through several experiments with different isolating conditions, temperature sensors and sample-sensor contacts. It is concluded that small to appreciable errors can appear, which are difficult to infer or control.

  5. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    SciTech Connect

    Zamstein, Noa; Tannor, David J.

    2012-12-14

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  6. Energy decomposition analysis in an adiabatic picture.

    PubMed

    Mao, Yuezhi; Horn, Paul R; Head-Gordon, Martin

    2017-02-22

    Energy decomposition analysis (EDA) of electronic structure calculations has facilitated quantitative understanding of diverse intermolecular interactions. Nevertheless, such analyses are usually performed at a single geometry and thus decompose a "single-point" interaction energy. As a result, the influence of the physically meaningful EDA components on the molecular structure and other properties are not directly obtained. To address this gap, the absolutely localized molecular orbital (ALMO)-EDA is reformulated in an adiabatic picture, where the frozen, polarization, and charge transfer energy contributions are defined as energy differences between the stationary points on different potential energy surfaces (PESs), which are accessed by geometry optimizations at the frozen, polarized and fully relaxed levels of density functional theory (DFT). Other molecular properties such as vibrational frequencies can thus be obtained at the stationary points on each PES. We apply the adiabatic ALMO-EDA to different configurations of the water dimer, the water-Cl(-) and water-Mg(2+)/Ca(2+) complexes, metallocenes (Fe(2+), Ni(2+), Cu(2+), Zn(2+)), and the ammonia-borane complex. This method appears to be very useful for unraveling how physical effects such as polarization and charge transfer modulate changes in molecular properties induced by intermolecular interactions. As an example of the insight obtained, we find that a linear hydrogen bond geometry for the water dimer is preferred even without the presence of polarization and charge transfer, while the red shift in the OH stretch frequency is primarily a charge transfer effect; by contrast, a near-linear geometry for the water-chloride hydrogen bond is achieved only when charge transfer is allowed.

  7. Static stability of the Jovian atmospheres estimated from moist adiabatic profiles

    NASA Astrophysics Data System (ADS)

    Sugiyama, Ko-ichiro; Odaka, Masatsugu; Kuramoto, Kiyoshi; Hayashi, Yoshi-Yuki

    2006-02-01

    The dependency of static stability N2 of the Jovian atmospheres on the abundances of condensible elements is considered by calculating the moist adiabatic profiles. An optimal minimization method of the Gibbs free energy is utilized to obtain equilibrium compositions in order to cover a variety of basic elements. It is shown that CH4 is one of the dominant contributors to producing a stable layer in the Uranian atmosphere. On Jupiter, R. K. Achterberg and A. P. Ingersoll (1989) have shown that, at low water abundances, N2 is proportional to the H2O abundance. In the present study, we show that this relationship does not hold when the H2O abundance is larger than approximately 5 × solar. A rough estimation of wave speed indicates that the abundance of 10 × solar is marginal to explain the SL9-induced wave speed as that of an internal gravity wave.

  8. Control of Diabatic versus Adiabatic Field Dissociation in a Heavy Rydberg System

    SciTech Connect

    Shiell, R.C.; Reinhold, E.; Ubachs, W.; Magnus, F.

    2005-11-18

    A novel phenomenon is observed in the dynamics of laser-prepared coherent wave packets, bound by the Coulombic 1/r potential of an ion-pair system. After exciting weakly bound ({approx_equal}3 meV) H{sup +}F{sup -} wave packets in a Stark field, and permitting them to evolve in time, control of field dissociation via adiabatic and diabatic routes is demonstrated by applying delayed pulsed-electric fields, involving a zero-field crossing. Control manifests itself through the production of ions from each pathway at a different instant in time. This phenomenon is applied to map the oscillatory behavior of an angular momentum wave packet in a heavy Rydberg system. The characteristic frequencies of the observed Stark oscillations verify predicted mass-scaling laws for heavy Rydberg systems.

  9. Direct Comparison of the Primary Blast Response of a Physical Head Model with Post-mortem Human Subjects

    DTIC Science & Technology

    2014-02-27

    Finally, external pressure fields from the blast wave generator experiments are compared to full scale free-field tests...rying locatio g very thin w ified to ensur ll scale blast 6 accelerome rotational acc parison of int ible; The natu ead orientatio nstrumentat the...sensor eter. It has th mely small. d to be ve n, FISO d ing the fibe 0 mm radiu not provid mation abou 1: The Blast-I TAL METH truction, mate for

  10. Neuronal and glial changes in the brain resulting from explosive blast in an experimental model.

    PubMed

    Goodrich, James A; Kim, Jung H; Situ, Robert; Taylor, Wesley; Westmoreland, Ted; Du, Fu; Parks, Steven; Ling, Geoffrey; Hwang, Jung Y; Rapuano, Amedeo; Bandak, Faris A; de Lanerolle, Nihal C

    2016-11-24

    Mild traumatic brain injury (mTBI) is the signature injury in warfighters exposed to explosive blasts. The pathology underlying mTBI is poorly understood, as this condition is rarely fatal and thus postmortem brains are difficult to obtain for neuropathological studies. Here we report on studies of an experimental model with a gyrencephalic brain that is exposed to single and multiple explosive blast pressure waves. To determine injuries to the brain resulting from the primary blast, experimental conditions were controlled to eliminate any secondary or tertiary injury from blasts. We found small but significant levels of neuronal loss in the hippocampus, a brain area that is important for cognitive functions. Furthermore, neuronal loss increased with multiple blasts and the degree of neuronal injury worsened with time post-blast. This is consistent with our findings in the blast-exposed human brain based on magnetic resonance spectroscopic imaging. The studies on this experimental model thus confirm what has been presumed to be the case with the warfighter, namely that exposure to multiple blasts causes increased brain injury. Additionally, as in other studies of both explosive blast as well as closed head mTBI, we found astrocyte activation. Activated microglia were also prominent in white matter tracts, particularly in animals exposed to multiple blasts and at long post-blast intervals, even though injured axons (i.e. β-APP positive) were not found in these areas. Microglial activation appears to be a delayed response, though whether they may contribute to inflammation related injury mechanism at even longer post-blast times than we tested here, remains to be explored. Petechial hemorrhages or other gross signs of vascular injury were not observed in our study. These findings confirm the development of neuropathological changes due to blast exposure. The activation of astrocytes and microglia, cell types potentially involved in inflammatory processes, suggest an

  11. Viscoelastic Materials Study for the Mitigation of Blast-Related Brain Injury

    NASA Astrophysics Data System (ADS)

    Bartyczak, Susan; Mock, Willis, Jr.

    2011-06-01

    Recent preliminary research into the causes of blast-related brain injury indicates that exposure to blast pressures, 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 sufficient to protect the warfighter from this danger and the effects are debilitating, costly, and long-lasting. Commercially available viscoelastic materials, designed to dampen vibration caused by shock waves, might be useful as helmet liners to dampen blast waves. The objective of this research is to develop an experimental technique to test these commercially available materials when subject to blast waves and evaluate their blast mitigating behavior. A 40-mm-bore gas gun is being used as a shock tube to generate blast waves (ranging from 1 to 500 psi) in a test fixture at the gun muzzle. A fast opening valve is used to release nitrogen gas from the breech to impact instrumented targets. The targets consist of aluminum/ viscoelastic polymer/ aluminum materials. Blast attenuation is determined through the measurement of pressure and accelerometer data in front of and behind the target. The experimental technique, calibration and checkout procedures, and results will be presented.

  12. Dawn-dusk asymmetry and adiabatic dynamic of the radiation belt electrons during magnetic storm

    NASA Astrophysics Data System (ADS)

    Lazutin, Leonid L.

    2016-09-01

    The changes of the latitudinal profiles of outer belt energetic electrons during magnetic storms are mostly explained by the precipitation into the loss cone caused by VLF and EMIC waves or by the scattering into the magnetopause. In present work, energetic electron dynamics during magnetic storm of August 29-30, 2004 we attributed at most to the adiabatic transformation of the magnetic drift trajectories and Dst effect. This conclusion was based on the analysis of dawn-dusk asymmetry of the electron latitudinal profiles measured by low altitude polar orbiter SERVIS-1 and on the coincidence of pre-storm and after-storm profiles of radiation belt electrons and protons.

  13. The adiabatic phase mixing and heating of electrons in Buneman turbulence

    SciTech Connect

    Che, H.; Goldstein, M. L.; Drake, J. F.; Swisdak, M.

    2013-06-15

    The nonlinear development of the strong Buneman instability and the associated fast electron heating in thin current layers with Ω{sub e}/ω{sub pe}<1 is explored. Phase mixing of the electrons in wave potential troughs and a rapid increase in temperature are observed during the saturation of the instability. We show that the motion of trapped electrons can be described using a Hamiltonian formalism in the adiabatic approximation. The process of separatrix crossing as electrons are trapped and de-trapped is irreversible and guarantees that the resulting electron energy gain is a true heating process.

  14. Lightweight blast shield

    SciTech Connect

    Mixon, Larry C.; Snyder, George W.; Hill, Scott D.; Johnson, Gregory L.; Wlodarski, J. Frank; von Spakovsky, Alexis P.; Emerson, John D.; Cole, James M.; Tipton, John P.

    1991-01-01

    A tandem warhead missile arrangement that has a composite material housing structure with a first warhead mounted at one end and a second warhead mounted near another end of the composite structure with a dome shaped composite material blast shield mounted between the warheads to protect the second warhead from the blast of the first warhead.

  15. Robotic Water Blast Cleaner

    NASA Technical Reports Server (NTRS)

    Sharpe, M. H.; Roberts, M. L.; Hill, W. E.; Jackson, C. H.

    1983-01-01

    Water blasting system under development removes hard, dense, extraneous material from surfaces. High pressure pump forces water at supersonic speed through nozzle manipulated by robot. Impact of water blasts away unwanted material from workpiece rotated on air bearing turntable. Designed for removing thermal-protection material, system is adaptable to such industrial processes as cleaning iron or steel castings.

  16. Constructing diabatic representations using adiabatic and approximate diabatic data – Coping with diabolical singularities

    SciTech Connect

    Zhu, Xiaolei Yarkony, David R.

    2016-01-28

    We have recently introduced a diabatization scheme, which simultaneously fits and diabatizes adiabatic ab initio electronic wave functions, Zhu and Yarkony J. Chem. Phys. 140, 024112 (2014). The algorithm uses derivative couplings in the defining equations for the diabatic Hamiltonian, H{sup d}, and fits all its matrix elements simultaneously to adiabatic state data. This procedure ultimately provides an accurate, quantifiably diabatic, representation of the adiabatic electronic structure data. However, optimizing the large number of nonlinear parameters in the basis functions and adjusting the number and kind of basis functions from which the fit is built, which provide the essential flexibility, has proved challenging. In this work, we introduce a procedure that combines adiabatic state and diabatic state data to efficiently optimize the nonlinear parameters and basis function expansion. Further, we consider using direct properties based diabatizations to initialize the fitting procedure. To address this issue, we introduce a systematic method for eliminating the debilitating (diabolical) singularities in the defining equations of properties based diabatizations. We exploit the observation that if approximate diabatic data are available, the commonly used approach of fitting each matrix element of H{sup d} individually provides a starting point (seed) from which convergence of the full H{sup d} construction algorithm is rapid. The optimization of nonlinear parameters and basis functions and the elimination of debilitating singularities are, respectively, illustrated using the 1,2,3,4{sup 1}A states of phenol and the 1,2{sup 1}A states of NH{sub 3}, states which are coupled by conical intersections.

  17. Blast-induced neurotrauma in whales.

    PubMed

    Knudsen, Siri K; Øen, Egil O

    2003-07-01

    A majority of investigations on primary blast injuries have focused on gas-containing organs, while the likelihood of blast-induced neurotrauma remains underrated. In Norway minke whales (Balaenoptera acutorostrata) are hunted using small fishing boats rigged with harpoon guns, which fire harpoons tipped with a grenade containing a charge of 30-g penthrite. The grenade detonates 60-70 cm inside the animal. The present study was undertaken to characterize the neuropathological changes caused by the penthrite blast and evaluate its role in the loss of consciousness and death in hunted whales. The study included 37 minke whales that were examined shipboard. The brains were later subjected to gross and light microscopy examination. The results showed that intra-body detonation of the grenade in near vicinity of the brain resulted in trauma similar to severe traumatic brain injury associated with a direct blow to the head. Detonation in more distant areas of the body resulted in injuries resembling acceleration-induced diffuse traumatic brain injury. The authors conclude that even if several vital organs were fatally injured in most whales, the neurotrauma induced by the blast-generated pressure waves were the primary cause for the immediate or very rapid loss of consciousness and death.

  18. On the General Class of Models of Adiabatic Evolution

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Lu, Songfeng; Liu, Fang

    2016-10-01

    The general class of models of adiabatic evolution was proposed to speed up the usual adiabatic computation in the case of quantum search problem. It was shown [8] that, by temporarily increasing the ground state energy of a time-dependent Hamiltonian to a suitable quantity, the quantum computation can perform the calculation in time complexity O(1). But it is also known that if the overlap between the initial and final states of the system is zero, then the computation based on the generalized models of adiabatic evolution can break down completely. In this paper, we find another severe limitation for this class of adiabatic evolution-based algorithms, which should be taken into account in applications. That is, it is still possible that this kind of evolution designed to deal with the quantum search problem fails completely if the interpolating paths in the system Hamiltonian are chosen inappropriately, while the usual adiabatic evolutions can do the same job relatively effectively. This implies that it is not always recommendable to use nonlinear paths in adiabatic computation. On the contrary, the usual simple adiabatic evolution may be sufficient for effective use.

  19. Effects of EOS adiabat on hot spot dynamics

    NASA Astrophysics Data System (ADS)

    Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Batha, Steven

    2013-10-01

    Equation of state (EOS) and adiabat of the pusher play significant roles in the dynamics and formation of the hot spot of an ignition capsule. For given imploding energy, they uniquely determine the partition of internal energy, mass, and volume between the pusher and the hot spot. In this work, we apply the new scaling laws recently derived by Cheng et al. to the National Ignition Campaign (NIC) ignition capsules and study the impacts of EOS and adiabat of the pusher on the hot spot dynamics by using the EOS adiabat index as an adjustable model parameter. We compare our analysis with the NIC data, specifically, for shots N120321 and N120205, and with the numerical simulations of these shots. The predictions from our theoretical model are in good agreements with the NIC data when a hot adiabat was used for the pusher, and with code simulations when a cold adiabat was used for the pusher. Our analysis indicates that the actual adiabat of the pusher in NIC experiments may well be higher than the adiabat assumed in the simulations. This analysis provides a physical and systematic explanation to the ongoing disagreements between the NIC experimental results and the multi-dimensional numerical simulations. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under contract number W-7405-ENG-36.

  20. Non-adiabatic perturbations in Ricci dark energy model

    SciTech Connect

    Karwan, Khamphee; Thitapura, Thiti E-mail: nanodsci2523@hotmail.com

    2012-01-01

    We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included.

  1. Effects of Primary Blast Overpressure on Retina and Optic Tract in Rats.

    PubMed

    DeMar, James; Sharrow, Keith; Hill, Miya; Berman, Jonathan; Oliver, Thomas; Long, Joseph

    2016-01-01

    Blast has been the leading cause of injury, particularly traumatic brain injury and visual system injury, in combat operations in Iraq and Afghanistan. We determined the effect of shock tube-generated primary blast on retinal electrophysiology and on retinal and brain optic tract histopathology in a rat model. The amplitude of a- and b-waves on the electroretinogram (ERG) for both right and left eyes were measured prior to a battlefield simulation Friedlander-type blast wave and on 1, 7, and 14 days thereafter. Histopathologic findings of the right and left retina and the right and left optic tracts (2.8 mm postoptic chiasm) were evaluated 14 days after the blast. For two experiments in which the right eye was oriented to the blast, the amplitude of ERG a- and b-waves at 7 days post blast on the right side but not on the left side was diminished compared to that of sham animals (P = 0.005-0.01) Histopathologic injury scores at 14 days post blast for the right retina but not the left retina were higher than for sham animals (P = 0.01), and histopathologic injury scores at 14 days for both optic tracts were markedly higher than for shams (P < 0.0001). Exposure of one eye to a blast wave, comparable to that causing human injury, produced injury to the retina as determined by ERG and histopathology, and to both postchiasmatic optic tracts as determined by histopathology. This model may be useful for analyzing the effect of therapeutic interventions on retinal damage due to primary blast waves.

  2. Effects of Primary Blast Overpressure on Retina and Optic Tract in Rats

    PubMed Central

    DeMar, James; Sharrow, Keith; Hill, Miya; Berman, Jonathan; Oliver, Thomas; Long, Joseph

    2016-01-01

    Blast has been the leading cause of injury, particularly traumatic brain injury and visual system injury, in combat operations in Iraq and Afghanistan. We determined the effect of shock tube-generated primary blast on retinal electrophysiology and on retinal and brain optic tract histopathology in a rat model. The amplitude of a- and b-waves on the electroretinogram (ERG) for both right and left eyes were measured prior to a battlefield simulation Friedlander-type blast wave and on 1, 7, and 14 days thereafter. Histopathologic findings of the right and left retina and the right and left optic tracts (2.8 mm postoptic chiasm) were evaluated 14 days after the blast. For two experiments in which the right eye was oriented to the blast, the amplitude of ERG a- and b-waves at 7 days post blast on the right side but not on the left side was diminished compared to that of sham animals (P = 0.005–0.01) Histopathologic injury scores at 14 days post blast for the right retina but not the left retina were higher than for sham animals (P = 0.01), and histopathologic injury scores at 14 days for both optic tracts were markedly higher than for shams (P < 0.0001). Exposure of one eye to a blast wave, comparable to that causing human injury, produced injury to the retina as determined by ERG and histopathology, and to both postchiasmatic optic tracts as determined by histopathology. This model may be useful for analyzing the effect of therapeutic interventions on retinal damage due to primary blast waves. PMID:27199884

  3. Autoresonant Dynamics of Optical Guided Waves

    SciTech Connect

    Barak, Assaf; Lamhot, Yuval; Segev, Mordechai; Friedland, Lazar

    2009-09-18

    We study, theoretically and experimentally, autoresonant dynamics of optical waves in a spatially chirped nonlinear directional coupler. We show that adiabatic passage through a linear resonance in a weakly coupled light-wave system yields a sharp threshold transition to nonlinear phase locking and amplification to predetermined amplitudes. This constitutes the first observation of autoresonance phenomena in optics.

  4. Dynamics of Charged Particles in an Adiabatic Thermal Beam Equilibrium

    NASA Astrophysics Data System (ADS)

    Chen, Chiping; Wei, Haofei

    2010-11-01

    Charged-particle motion is studied in the self-electric and self-magnetic fields of a well-matched, intense charged-particle beam and an applied periodic solenoidal magnetic focusing field. The beam is assumed to be in a state of adiabatic thermal equilibrium. The phase space is analyzed and compared with that of the well-known Kapchinskij-Vladimirskij (KV)-type beam equilibrium. It is found that the widths of nonlinear resonances in the adiabatic thermal beam equilibrium are narrower than those in the KV-type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.

  5. Implementation of Immersed Boundary Method in WENO Scheme to Simulate Blast-Structure Interaction

    NASA Astrophysics Data System (ADS)

    Xu, Min; Yang, Tao; Wei, Mingjun

    2014-11-01

    High-order WENO schemes have been widely used in numerical simulation of shock/blast waves; and immersed boundary method has been gradually accepted as a simple and powerful approach to deal with moving boundaries in computational fluid dynamics. The combination of these two techniques becomes a natural choice in our study of blast-structure interaction. To benchmark our combined approach, we applied it first on classical shockwave problems with exact solutions or well-tested numerical solutions. Then, the algorithm is applied to simulate the interaction between an incoming blast wave and a spring-linked cylinder. Finally, a more complex case, where multiple plates linked by springs are interacting with blast waves and each other, has been investigated. Supported by ARL (AHPCRC).

  6. An investigation of a reticulated foam - perforated steel sheet combination as a blast mitigation structure

    NASA Astrophysics Data System (ADS)

    Nguyen, Thuy-Tien N.; Proud, William G.

    2017-01-01

    Explosions are one of the main causes of injuries during battles and conflicts, with improvised explosive devices (IEDs) becoming increasingly common. Blast waves produced from such explosions can inflict very complex injuries on human and serious damage to structures. Here, the interaction between blast waves and sandwich structures of reticulated foam and perforated sheets is studied using a shock tube. The level of mitigation for primary blast injuries of these structures are discussed in terms of pulse shape, pressure magnitude and impulse. Schlieren photography and other high-speed imaging were used to capture the form of the blast wave. The results show up to 95% mitigation in both pressure and impulse with the structures studied. The behaviors of these mitigating sandwich panels under two loadings, Mach 2.0 and Mach 2.6, are also discussed.

  7. Adiabatic channel capture theory applied to cold atom-molecule reactions: Li + CaH \\to LiH + Ca at 1K

    NASA Astrophysics Data System (ADS)

    Tscherbul, Timur V.; Buchachenko, Alexei A.

    2015-03-01

    We use quantum and classical adiabatic capture theories to study the chemical reaction Li + CaH \\to LiH + Ca. Using a recently developed ab initio potential energy surface, which provides an accurate representation of long-range interactions in the entrance reaction channel, we calculate the adiabatic channel potentials by diagonalizing the Li-CaH Hamiltonian as a function of the atom-molecule separation. The resulting adiabatic channel potentials are used to calculate both the classical and quantum capture probabilities as a function of collision energy, as well as the temperature dependencies of the partial and total reaction rates. The calculated reaction rate agrees well with the measured value at 1 K (V Singh et al 2012 Phys. Rev. Lett. 108 203201), suggesting that the title reaction proceeds without an activation barrier. The calculated classical adiabatic capture rate agrees well with the quantum result in the multiple-partial-wave regime of relevance to the experiment. Significant differences are found only in the ultracold limit (T\\lt 1 mK), demonstrating that adiabatic capture theories can predict the reaction rates with nearly quantitative accuracy in the multiple-partial-wave regime.

  8. Deep blast

    NASA Astrophysics Data System (ADS)

    From southern New Mexico to the Great Slave Lake of Canada, scientists from the United States and Canada recently detonated 10 underground chemical explosions to generate a clearer picture of the Earth's crust and upper mantle. Called Project Deep Probe, the experiment is designed to see through the crust and into the upper mantle to a depth of 300 miles.In the United States, Earth scientists from Rice University, Purdue University, and the University of Oregon are participating in the project. “Researchers hope to get a picture of the upper mantle beneath the Rocky Mountains and the Colorado Plateau, to understand the role the mantle played in formation and uplift,” says Alan Levander of Rice. To enhance that “picture,” 750 portable seismographs were placed along a roughly north-south line extending from Crownpoint, New Mexico to Edmonton, Alberta. The seismic recordings will be used to enhance weak seismic waves that penetrated the upper mantle.

  9. Quantum adiabatic optimization and combinatorial landscapes

    NASA Astrophysics Data System (ADS)

    Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.

    2004-09-01

    In this paper we analyze the performance of the Quantum Adiabatic Evolution algorithm on a variant of the satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, γ=M/N . We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (instead of only energy) is used, and are able to show the existence of a dynamic threshold γ=γd starting with some value of K —the number of variables in each clause. Beyond the dynamic threshold, the algorithm should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz. We have been able to map the ensemble of random graphs onto another ensemble with fluctuations significantly reduced. This enabled us to obtain tight upper bounds on the satisfiability transition and to recompute the dynamical transition using the extended set of landscapes.

  10. Design of the PIXIE adiabatic demagnetization refrigerators

    NASA Astrophysics Data System (ADS)

    Shirron, Peter J.; Kimball, Mark O.; Fixsen, Dale J.; Kogut, Alan J.; Li, Xiaoyi; DiPirro, Michael J.

    2012-04-01

    The Primordial Inflation Explorer (PIXIE) is a proposed mission to densely map the polarization of the cosmic microwave background. It will operate in a scanning mode from a sun-synchronous orbit, using low temperature detectors (at 0.1 K) and located inside a telescope that is cooled to approximately 2.73 K - to match the background temperature. A mechanical cryocooler operating at 4.5 K establishes a low base temperature from which two adiabatic demagnetization refrigerator (ADR) assemblies will cool the telescope and detectors. To achieve continuous scanning capability, the ADRs must operate continuously. Complicating the design are two factors: (1) the need to systematically vary the temperature of various telescope components in order to separate the small polarization signal variations from those that may arise from temperature drifts and changing gradients within the telescope, and (2) the orbital and monthly variations in lunar irradiance into the telescope barrels. These factors require the telescope ADR to reject quasi-continuous heat loads of 2-3 mW, while maintaining a peak heat reject rate of less than 12 mW. The detector heat load at 0.1 K is comparatively small at 1-2 μW. This paper will describe the 3-stage and 2-stage continuous ADRs that will be used to meet the cooling power and temperature stability requirements of the PIXIE detectors and telescope.

  11. Adiabatic quantum algorithm for search engine ranking.

    PubMed

    Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A

    2012-06-08

    We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in "q-sampling" protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank.

  12. Adiabatic Quantum Algorithm for Search Engine Ranking

    NASA Astrophysics Data System (ADS)

    Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A.

    2012-06-01

    We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log⁡(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in “q-sampling” protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank.

  13. On the persistence of adiabatic shear bands

    NASA Astrophysics Data System (ADS)

    Boakye-Yiadom, S.; Bassim, M. N.; Al-Ameeri, S.

    2012-08-01

    It is generally agreed that the initiation and development of adiabatic shear bands (ASBs) are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment) or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the "scars" due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.

  14. Adiabatic Spin Pumping with Quantum Dots

    NASA Astrophysics Data System (ADS)

    Mucciolo, Eduardo R.

    Electronic transport in mesoscopic systems has been intensively studied for more the last three decades. While there is a substantial understanding of the stationary regime, much less is know about phase-coherent nonequilibrium transport when pulses or ac perturbations are used to drive electrons at low temperatures and at small length scales. However, about 20 years ago Thouless proposed to drive nondissipative currents in quantum systems by applying simultaneously two phase-locked external perturbations. The so-called adiabatic pumping mechanism has been revived in the last few years, both theoretically and experimentally, in part because of the development of lateral semiconductor quantum dots. Here we will explain how open dots can be used to create spin-polarized currents with little or no net charge transfer. The pure spin pump we propose is the analog of a charge battery in conventional electronics and may provide a needed circuit element for spin-based electronics. We will also discuss other relevant issues such as rectification and decoherence and point out possible extensions of the mechanism to closed dots.

  15. Passive blast pressure sensor

    DOEpatents

    King, Michael J.; Sanchez, Roberto J.; Moss, William C.

    2013-03-19

    A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

  16. Adiabatic shear bands localization in materials undergoing deformations

    NASA Astrophysics Data System (ADS)

    Ryabov, P. N.; Kudryashov, N. A.; Muratov, R. V.

    2017-01-01

    We consider the adiabatic shear banding phenomenon in composite materials undergoing the high speed shear deformations. The mathematical model of adiabatic shear banding in thermo-visco-plastic material is given. New two step numerical algorithm which is based on the Courant-Isaacson-Rees scheme that allows one to simulate fully localized plastic flow from initial stage of localization is proposed. To test this numerical algorithm we use three benchmark problems. The testing results show the accuracy and efficiency of proposed algorithm. The features of adiabatic shear bands formation in composites are studied. The existence of characteristic depth of localization in composites is shown. Influence of initial temperature distribution on the processes of adiabatic shear bands formation in composites is considered.

  17. Adiabaticity and spectral splits in collective neutrino transformations

    SciTech Connect

    Raffelt, Georg G.; Smirnov, Alexei Yu.

    2007-12-15

    Neutrinos streaming off a supernova core transform collectively by neutrino-neutrino interactions, leading to 'spectral splits' where an energy E{sub split} divides the transformed spectrum sharply into parts of almost pure but different flavors. We present a detailed description of the spectral-split phenomenon which is conceptually and quantitatively understood in an adiabatic treatment of neutrino-neutrino effects. Central to this theory is a self-consistency condition in the form of two sum rules (integrals over the neutrino spectra that must equal certain conserved quantities). We provide explicit analytic and numerical solutions for various neutrino spectra. We introduce the concept of the adiabatic reference frame and elaborate on the relative adiabatic evolution. Violating adiabaticity leads to the spectral split being 'washed out'. The sharpness of the split appears to be represented by a surprisingly universal function.

  18. Adiabatic and isocurvature perturbation projections in multi-field inflation

    SciTech Connect

    Gordon, Chris; Saffin, Paul M. E-mail: Paul.Saffin@nottingham.ac.uk

    2013-08-01

    Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit.

  19. Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses

    SciTech Connect

    Dridi, G.; Guerin, S.; Hakobyan, V.; Jauslin, H. R.; Eleuch, H.

    2009-10-15

    We present a general and versatile technique of population transfer based on parallel adiabatic passage by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3{pi}, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically picosecond and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ultrafast robust population transfer with interesting applications in quantum information processing.

  20. Vascular and inflammatory factors in the pathophysiology of blast-induced brain injury.

    PubMed

    Elder, Gregory A; Gama Sosa, Miguel A; De Gasperi, Rita; Stone, James Radford; Dickstein, Dara L; Haghighi, Fatemeh; Hof, Patrick R; Ahlers, Stephen T

    2015-01-01

    Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI.

  1. Vascular and Inflammatory Factors in the Pathophysiology of Blast-Induced Brain Injury

    PubMed Central

    Elder, Gregory A.; Gama Sosa, Miguel A.; De Gasperi, Rita; Stone, James Radford; Dickstein, Dara L.; Haghighi, Fatemeh; Hof, Patrick R.; Ahlers, Stephen T.

    2015-01-01

    Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI. PMID:25852632

  2. Applications and error correction for adiabatic quantum optimization

    NASA Astrophysics Data System (ADS)

    Pudenz, Kristen

    Adiabatic quantum optimization (AQO) is a fast-developing subfield of quantum information processing which holds great promise in the relatively near future. Here we develop an application, quantum anomaly detection, and an error correction code, Quantum Annealing Correction (QAC), for use with AQO. The motivation for the anomaly detection algorithm is the problematic nature of classical software verification and validation (V&V). The number of lines of code written for safety-critical applications such as cars and aircraft increases each year, and with it the cost of finding errors grows exponentially (the cost of overlooking errors, which can be measured in human safety, is arguably even higher). We approach the V&V problem by using a quantum machine learning algorithm to identify charateristics of software operations that are implemented outside of specifications, then define an AQO to return these anomalous operations as its result. Our error correction work is the first large-scale experimental demonstration of quantum error correcting codes. We develop QAC and apply it to USC's equipment, the first and second generation of commercially available D-Wave AQO processors. We first show comprehensive experimental results for the code's performance on antiferromagnetic chains, scaling the problem size up to 86 logical qubits (344 physical qubits) and recovering significant encoded success rates even when the unencoded success rates drop to almost nothing. A broader set of randomized benchmarking problems is then introduced, for which we observe similar behavior to the antiferromagnetic chain, specifically that the use of QAC is almost always advantageous for problems of sufficient size and difficulty. Along the way, we develop problem-specific optimizations for the code and gain insight into the various on-chip error mechanisms (most prominently thermal noise, since the hardware operates at finite temperature) and the ways QAC counteracts them. We finish by showing

  3. Shortcuts to adiabaticity for non-Hermitian systems

    SciTech Connect

    Ibanez, S.; Martinez-Garaot, S.; Torrontegui, E.; Muga, J. G.; Chen Xi

    2011-08-15

    Adiabatic processes driven by non-Hermitian, time-dependent Hamiltonians may be sped up by generalizing inverse engineering techniques based on counter-diabatic (transitionless driving) algorithms or on dynamical invariants. We work out the basic theory and examples described by two-level Hamiltonians: the acceleration of rapid adiabatic passage with a decaying excited level and of the dynamics of a classical particle on an expanding harmonic oscillator.

  4. Nonadiabatic transitions in finite-time adiabatic rapid passage

    NASA Astrophysics Data System (ADS)

    Lu, T.; Miao, X.; Metcalf, H.

    2007-06-01

    To apply the adiabatic rapid passage process repetitively [T. Lu, X. Miao, and H. Metcalf, Phys. Rev. A 71, 061405(R) (2005)], the nonadiabatic transition probability of a two-level atom subject to chirped light pulses over a finite period of time needs to be calculated. Using a unitary first-order perturbation method in the rotating adiabatic frame, an approximate formula has been derived for such transition probabilities in the entire parameter space of the pulses.

  5. Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments

    SciTech Connect

    DeLucia, J.; Bell, M.; Wong, K.L.

    1985-07-01

    A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability.

  6. Injury biomechanics, neuropathology, and simplified physics of explosive blast and impact mild traumatic brain injury.

    PubMed

    Bandak, F A; Ling, G; Bandak, A; De Lanerolle, N C

    2015-01-01

    Explosive blast shock waves and blunt impact to the head are two types of loading shown to result in mild traumatic brain injury (mTBI). While mTBI from these two causes shares some common features behaviorally, there are distinct differences in the pathophysiology of the underlying injury mechanisms. Various elucidations have been offered in the literature to explain the organic damage associated with mTBI resulting from both types of loading. The current state of understanding in this field is somewhat limited by the degree of appreciation of the physics and biomechanics governing the effects of explosive blast shock waves and blunt impact on the head, which has resulted in the various approaches to the investigation of the operative brain injury "wounding mechanisms". In this chapter we provide a simplified description of terminology associated with forces on the head from explosive blast shock waves and blunt impact, to assist readers in the field in evaluating interpretations of brain injury "wounding" processes. Remarkably, mTBI from either loading is shown generally to result in only a small loss of neurons, with hippocampal neurons appearing to be particularly vulnerable to explosive blast shock waves. Explosive blast studies in large animal models show a unique pattern of periventricular injury, which is different from the classic diffuse axonal injury. Both astrocyte and microglial activation are also seen in explosive blast as well as impact trauma, but this may be a general secondary brain injury response, nonspecific to explosive blast or blunt trauma. Additionally, while moderate to severe impact closed head injuries sometimes result in petechial hemorrhages or hematomas, they do not appear to be associated with explosive blast mTBI even with repeated exposure to blasts.

  7. A connection between mix and adiabat in ICF capsules

    NASA Astrophysics Data System (ADS)

    Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Yi, Sunghuan (Austin); Batha, Steven

    2016-10-01

    We study the relationship between instability induced mix, preheat and the adiabat of the deuterium-tritium (DT) fuel in fusion capsule experiments. Our studies show that hydrodynamic instability not only directly affects the implosion, hot spot shape and mix, but also affects the thermodynamics of the capsule, such as, the adiabat of the DT fuel, and, in turn, affects the energy partition between the pusher shell (cold DT) and the hot spot. It was found that the adiabat of the DT fuel is sensitive to the amount of mix caused by Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities at the material interfaces due to its exponential dependence on the fuel entropy. An upper limit of mix allowed maintaining a low adiabat of DT fuel is derived. Additionally we demonstrated that the use of a high adiabat for the DT fuel in theoretical analysis and with the aid of 1D code simulations could explain some aspects of the 3D effects and mix in the capsule experiments. Furthermore, from the observed neutron images and our physics model, we could infer the adiabat of the DT fuel in the capsule and determine the possible amount of mix in the hot spot (LA-UR-16-24880). This work was conducted under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

  8. Adiabatic and non-adiabatic charge pumping in a single-level molecular motor

    NASA Astrophysics Data System (ADS)

    Napitu, B. D.; Thijssen, J. M.

    2015-07-01

    We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green’s function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups.

  9. Adiabatic and non-adiabatic charge pumping in a single-level molecular motor.

    PubMed

    Napitu, B D; Thijssen, J M

    2015-07-15

    We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green's function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups.

  10. Blast Dynamics in a Dissipative Gas.

    PubMed

    Barbier, M; Villamaina, D; Trizac, E

    2015-11-20

    The blast caused by an intense explosion has been extensively studied in conservative fluids, where the Taylor-von Neumann-Sedov hydrodynamic solution is a prototypical example of self-similarity driven by conservation laws. In dissipative media, however, energy conservation is violated, yet a distinctive self-similar solution appears. It hinges on the decoupling of random and coherent motion permitted by a broad class of dissipative mechanisms. This enforces a peculiar layered structure in the shock, for which we derive the full hydrodynamic solution, validated by a microscopic approach based on molecular dynamics simulations. We predict and evidence a succession of temporal regimes, as well as a long-time corrugation instability, also self-similar, which disrupts the blast boundary. These generic results may apply from astrophysical systems to granular gases, and invite further cross-fertilization between microscopic and hydrodynamic approaches of shock waves.

  11. Adiabatic transfer of light in a double cavity and the optical Landau-Zener problem

    SciTech Connect

    Miladinovic, N.; Hasan, F.; Linnington, I. E.; O'Dell, D. H. J.; Chisholm, N.; Hinds, E. A.

    2011-10-15

    We analyze the evolution of an electromagnetic field inside a double cavity when the difference in length between the two cavities is changed, e.g., by translating the common mirror. We find that this allows photons to be moved deterministically from one cavity to the other. We are able to obtain the conditions for adiabatic transfer by first mapping the Maxwell wave equation for the electric field onto a Schroedinger-like wave equation and then using the Landau-Zener result for the transition probability at an avoided crossing. Our analysis reveals that this mapping only rigorously holds when the two cavities are weakly coupled (i.e., in the regime of a highly reflective common mirror) and that, generally speaking, care is required when attempting a Hamiltonian description of cavity electrodynamics with time-dependent boundary conditions.

  12. Adiabatic fission barriers in superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Jachimowicz, P.; Kowal, M.; Skalski, J.

    2017-01-01

    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy, we calculated static fission barriers Bf for 1305 heavy and superheavy nuclei 98 ≤Z ≤126 , including even-even, odd-even, even-odd and odd-odd systems. For odd and odd-odd nuclei, adiabatic potential-energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10th below to the 10th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "imaginary water flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole nonaxiality. The ground states (g.s.) were found by energy minimization over configurations and deformations. We find that the nonaxiality significantly changes first and second fission saddle in many nuclei. The effect of the mass asymmetry, known to lower the second, very deformed saddles in actinides, in the heaviest nuclei appears at the less deformed saddles in more than 100 nuclei. It happens for those saddles in which the triaxiality does not play any role, which suggests a decoupling between effects of the mass asymmetry and triaxiality. We studied also the influence of the pairing interaction strength on the staggering of Bf for odd- and even-particle numbers. Finally, we provide a comparison of our results with other theoretical fission barrier evaluations and with available experimental estimates.

  13. Effects of Low-Level Blast Exposure on the Nervous System: Is There Really a Controversy?

    PubMed Central

    Elder, Gregory A.; Stone, James R.; Ahlers, Stephen T.

    2014-01-01

    High-pressure blast waves can cause extensive CNS injury in human beings. However, in combat settings, such as Iraq and Afghanistan, lower level exposures associated with mild traumatic brain injury (mTBI) or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD). We describe how TBI is defined in human beings and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in human beings is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments, a condition of “low-level” blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet, animal studies show that low-level blast pressure waves are transmitted to the brain. In brain, low-level blast exposures cause behavioral, biochemical, pathological, and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long

  14. Computer cast blast modelling

    SciTech Connect

    Chung, S.; McGill, M.; Preece, D.S.

    1994-07-01

    Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than normal is required plus an initiation technique designed to produce a much greater degree of horizontal muck movement. This paper compares two blast models known as DMC (Distinct Motion Code) and SABREX (Scientific Approach to Breaking Rock with Explosives). DMC, applies discrete spherical elements interacted with the flow of explosive gases and the explicit time integration to track particle motion resulting from a blast. The input to this model includes multi-layer rock properties, and both loading geometry and explosives equation-of-state parameters. It enables the user to have a wide range of control over drill pattern and explosive loading design parameters. SABREX assumes that heave process is controlled by the explosive gases which determines the velocity and time of initial movement of blocks within the burden, and then tracks the motion of the blocks until they come to a rest. In order to reduce computing time, the in-flight collisions of blocks are not considered and the motion of the first row is made to limit the motion of subsequent rows. Although modelling a blast is a complex task, the DMC can perform a blast simulation in 0.5 hours on the SUN SPARCstation 10--41 while the new SABREX 3.5 produces results of a cast blast in ten seconds on a 486-PC computer. Predicted percentage of cast and face velocities from both computer codes compare well with the measured results from a full scale cast blast.

  15. Adiabatic Computation of Internal Blast from Aluminum-Cased Charges in Air.

    DTIC Science & Technology

    1982-01-01

    relation K = K (V/RT) An (6)p n where Aln is the change in number of moles of gas for the synthesis reaction . Then for any species the mole number is...point, to an increasing extent, A12 0 3 () is being converted to A12 0(g) by the endothermic (energy-absorbing) reaction AI2.0 3 (l) + 4 Al - 3 AI20(g...effect. 1. Simple production of aluminum nitride: AI(l) + 1/2N,(g) -AIN(s) The reaction is strongly exothermic (though less so than the production of

  16. Creating and studying ion acoustic waves in ultracold neutral plasmas

    SciTech Connect

    Killian, T. C.; Castro, J.; McQuillen, P.; O'Neil, T. M.

    2012-05-15

    We excite ion acoustic waves in ultracold neutral plasmas by imprinting density modulations during plasma creation. Laser-induced fluorescence is used to observe the density and velocity perturbations created by the waves. The effect of expansion of the plasma on the evolution of the wave amplitude is described by treating the wave action as an adiabatic invariant. After accounting for this effect, we determine that the waves are weakly damped, but the damping is significantly faster than expected for Landau damping.

  17. Experimental Investigation on the Basic Law of the Fracture Spatial Morphology for Water Pressure Blasting in a Drillhole Under True Triaxial Stress

    NASA Astrophysics Data System (ADS)

    Huang, Bingxiang; Li, Pengfeng

    2015-07-01

    The present literature on the morphology of water pressure blasting fractures in drillholes is not sufficient and does not take triaxial confining stress into account. Because the spatial morphology of water pressure blasting fractures in drillholes is not clear, the operations lack an exact basis. Using a large true triaxial water pressure blasting experimental system and an acoustic emission 3-D positioning system, water pressure blasting experiments on cement mortar test blocks (300 mm × 300 mm × 300 mm) were conducted to study the associated basic law of the fracture spatial morphology. The experimental results show that water pressure blasting does not always generate bubble pulsation. After water pressure blasting under true triaxial stress, a crushed compressive zone and a blasting fracture zone are formed from the inside, with the blasting section of the naked drillhole as the center, to the outside. The shape of the outer edges of the two zones is ellipsoidal. The range of the blasting fracture is large in the radial direction of the drillhole, where the surrounding pressure is large, i.e., the range of the blasting fracture in the drillhole radial cross-section is approximately ellipsoidal. The rock near the drillhole wall is affected by a tensile stress wave caused by the test block boundary reflection, resulting in more flake fractures appearing in the fracturing crack surface in the drillhole axial direction and parallel to the boundary surface. The flake fracture is thin, presenting a small-range flake fracture. The spatial morphology of the water pressure blasting fracture in the drillhole along the axial direction is similar to a wide-mouth Chinese bottle: the crack extent is large near the drillhole orifice, gradually narrows inward along the drillhole axial direction, and then increases into an approximate ellipsoid in the internal naked blasting section. Based on the causes of the crack generation, the blasting cracks are divided into three

  18. Cerebrovascular Injury in Blast Loading

    DTIC Science & Technology

    2010-01-01

    TITLE: Cerebrovascular injury in blast loading PRINCIPAL INVESTIGATOR: Kenneth L. Monson, PhD...SUBTITLE Cerebrovascular injury in blast loading 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-08-1-0295 5c. PROGRAM ELEMENT NUMBER 6...and pH control. 15. SUBJECT TERMS Blast brain injury; cerebrovascular injury and dysfunction; shock tube 16. SECURITY CLASSIFICATION OF: 17

  19. LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views

    NASA Astrophysics Data System (ADS)

    Anacleto, Joaquim; Pereira, Mário G.

    2009-05-01

    The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.

  20. Bomb blast mass casualty incidents: initial triage and management of injuries.

    PubMed

    Goh, S H

    2009-01-01

    Bomb blast injuries are no longer confined to battlefields. With the ever present threat of terrorism, we should always be prepared for bomb blasts. Bomb blast injuries tend to affect air-containing organs more, as the blast wave tends to exert a shearing force on air-tissue interfaces. Commonly-injured organs include the tympanic membranes, the sinuses, the lungs and the bowel. Of these, blast lung injury is the most challenging to treat. The clinical picture is a mix of acute respiratory distress syndrome and air embolism, and the institution of positive pressure ventilation in the presence of low venous pressures could cause systemic arterial air embolism. The presence of a tympanic membrane perforation is not a reliable indicator of the presence of a blast injury in the other air-containing organs elsewhere. Radiological imaging of the head, chest and abdomen help with the early identification of blast lung injury, head injury, abdominal injury, eye and sinus injuries, as well as any penetration by foreign bodies. In addition, it must be borne in mind that bomb blasts could also be used to disperse radiological and chemical agents.

  1. Effects of repetitive low-pressure explosive blast on primary neurons and mixed cultures.

    PubMed

    Zander, Nicole E; Piehler, Thuvan; Banton, Rohan; Benjamin, Richard

    2016-09-01

    Repetitive mild traumatic brain injury represents a considerable health concern, particularly for athletes and military personnel. For blast-induced brain injury, threshold shock-impulse levels required to induce such injuries and cumulative effects with single and/or multiple exposures are not well characterized. Currently, there is no established in vitro experimental model with blast pressure waves generated by live explosives. This study presents results of primary neurons and mixed cultures subjected to our unique in vitro indoor experimental platform that uses real military explosive charges to probe the effects of primary explosive blast at the cellular level. The effects of the blast on membrane permeability, generation of reactive oxygen species (ROS), uptake of sodium ions, intracellular calcium, and release of glutamate were probed 2 and 24 hr postblast. Significant changes in membrane permeability and sodium uptake among the sham, single-blast-injured, and triple-blast-injured samples were observed. A significant increase in ROS and glutamate release was observed for the triple-blast-injured samples compared with the sham. Changes in intracellular calcium were not significant. These results suggest that blast exposure disrupts the integrity of the plasma membrane, leading to the upset of ion homeostasis, formation of ROS, and glutamate release. Published 2016. †This article is a U.S. Government work and is in the public domain in the USA.

  2. Acute Inflammatory Response in Rodent Brain and Blood Following a Blast Induced Traumatic Brain Injury

    DTIC Science & Technology

    2014-11-01

    population is exposure to a blast wave. The shockwave produced by an explosive device can travel through the brain causing mild brain damage without any...comparing cytokine levels in rat brain and blood at various time points after a shockwave exposure. . Defence Research and Analysis Canada...Animal Care Committee prior to the use of any animals in this study. Shockwave exposure: A custom built blast simulator (approx. 30.5cm in diameter and

  3. Concept Validation and Optimization for a Vent-Based Mine-Blast Mitigation System

    DTIC Science & Technology

    2015-01-17

    SECURITY CLASSIFICATION OF: In this project, a new solution for improving blast-survivability of light tactical military vehicles to detonation of a...the V-shaped vehicle underbody, and tries to exploit detonation -products’ ultrasonic-expansion and ejected-soil venting phenomena to generate a...downward thrust on the targeted vehicle. In order to accurately account for the interaction of detonation products, ejected soil and blast waves with the

  4. Design of armor for protection against blast and impact

    NASA Astrophysics Data System (ADS)

    Rahimzadeh, Tanaz; Arruda, Ellen M.; Thouless, M. D.

    2015-12-01

    The features of blast and impact that can damage a delicate target supported by a structure include both the peak pressure and the impulse delivered to the structure. This study examines how layers of elastic and visco-elastic materials may be assembled to mitigate these features. The impedance mismatch between two elastic layers is known to reduce the pressure, but dissipation is required to mitigate the transmitted impulse in light-weight armor. A novel design concept called impact or blast tuning is introduced in which a multi-layered armor is used to tune the stress waves resulting from an impact or blast to specific frequencies that match the damping frequencies of visco-elastic layers. The material and geometrical parameters controlling the viscous dissipation of the energy within the armor are identified for a simplified one-dimensional system, to provide insight into how the optimal design of multi-use armor might be based on this concept.

  5. Fidelity of adiabatic holonomic quantum gates

    NASA Astrophysics Data System (ADS)

    Malinovsky, Vladimir; Rudin, Sergey

    2016-05-01

    During last few years non-Abelian geometric phases are attracting increasing interest due to possible experimental applications in quantum computation. Here we discuss universal set of holonomic quantum gates using the geometric phase that the qubit wave function acquires after a cyclic evolution. The proposed scheme utilizes ultrafast pulses and provides a possibility to substantially suppress transient population of the ancillary states. Fidelity of the holonomic quantum gates in the presence of dephasing and dissipation is discussed. Example of electron spin qubit system in the InGaN/GaN, GaN/AlN quantum dot is considered in details.

  6. Shortcuts to adiabaticity in a time-dependent box

    PubMed Central

    Campo, A. del; Boshier, M. G.

    2012-01-01

    A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential. PMID:22970340

  7. Adiabatic circular polarizer based on chiral fiber grating.

    PubMed

    Yang, Li; Xue, Lin-Lin; Li, Cheng; Su, Jue; Qian, Jing-Ren

    2011-01-31

    Based on the adiabatic coupling principle, a new scheme of a broadband circular polarizer formed by twisting a high-birefringence (Hi-Bi) fiber with a slowly varying twist rate is proposed. The conditions of adiabatic coupling for the adiabatic polarizer are first identified through analytical derivations. These conditions are easily realized by choosing a reasonable variation of the twist rate. Moreover, the bandwidth of the polarizer is able to be directly determined by the twist rates at the two ends. Finally, the broadband characteristics of the polarizer are demonstrated by simulations. It is also shown that the performance of the polarizer can be remarkably improved by accomplishing a multi-mode phase-matching along the grating or by using of the couplings of the core mode to lossy modes.

  8. Effect of dephasing on stimulated Raman adiabatic passage

    SciTech Connect

    Ivanov, P.A.; Vitanov, N.V.; Bergmann, K.

    2004-12-01

    This work explores the effect of phase relaxation on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The study is based on the Liouville equation, which is solved analytically in the adiabatic limit. The transfer efficiency of STIRAP is found to decrease exponentially with the dephasing rate; this effect is stronger for shorter pulse delays and weaker for larger delays, since the transition time is found to be inversely proportional to the pulse delay. Moreover, it is found that the transfer efficiency of STIRAP in the presence of dephasing does not depend on the peak Rabi frequencies at all, as long as they are sufficiently large to enforce adiabatic evolution; hence increasing the field intensity cannot reduce the dephasing losses. It is shown also that for any dephasing rate, the final populations of the initial state and the intermediate state are equal. For strong dephasing all three populations tend to (1/3)

  9. Applications of chirped Raman adiabatic rapid passage to atom interferometry

    NASA Astrophysics Data System (ADS)

    Kotru, Krish; Butts, David L.; Kinast, Joseph M.; Johnson, David M. S.; Radojevic, Antonije M.; Timmons, Brian P.; Stoner, Richard E.

    2012-02-01

    We present robust atom optics, based on chirped Raman adiabatic rapid passage (ARP), in the context of atom interferometry. Such ARP light pulses drive coherent population transfer between two hyperfine ground states by sweeping the frequency difference of two fixed-intensity optical fields with large single photon detunings. Since adiabatic transfer is less sensitive to atom temperature and non-uniform Raman beam intensity than standard Raman pulses, this approach should improve the stability of atom interferometers operating in dynamic environments. In such applications, chirped Raman ARP may also provide advantages over the previously demonstrated stimulated Raman adiabatic passage (STIRAP) technique, which requires precise modulation of beam intensity and zeroing of the single photon detuning. We demonstrate a clock interferometer with chirped Raman ARP pulses, and compare its stability to that of a conventional Raman pulse interferometer. We also discuss potential improvements to inertially sensitive atom interferometers. Copyright 2011 by The Charles Stark Draper Laboratory, Inc. All rights reserved.

  10. Adiabatic Pseudospectral Technique: Applications to Four Atom Molecules

    NASA Astrophysics Data System (ADS)

    Antikainen, Jyrki Tapio

    1995-01-01

    After the introduction, in chapter 2 we review some of the well established techniques used to solve the Schrodinger equation. The following methods are discussed: the Finite Basis Representation, the Discrete Variable Representation, the Basic Light basis set truncation, and the Lanczos tridiagonalization. After reviewing the previous techniques we present the main features of our Adiabatic Pseudospectral (APS) technique. The Adiabatic Pseudospectral technique is a synthesis of several powerful computational methods such as the sequential adiabatic basis set reduction, the iterative Lanczos diagonalization, the collocation techniques, and a careful implementation of the matrix -vector product for the Hamiltonian in the reduced adiabatic representation. In chapter 3 we use our adiabatic pseudospectral method (APS) to calculate energy levels of the H _2O_2 molecule up to 5000 cm ^{-1}. Reasonably high accuracy (a few wavenumbers) is achieved for a fully six dimensional calculation in a few hours of CPU time on an IBM 580 workstation. These results are a great improvement over previous calculations on the same system which required 50-100 times more computational effort for a similar level of accuracy. The method presented here is both general and robust. It will allow for routine studies of six dimensional potential surfaces and the associated spectroscopy, while making calculations on still larger systems feasible. In chapter 4 the adiabatic pseudospectral method is used to study the high energy vibrational levels of the H_2C_2 molecule. We calculate stimulated emission pumping spectra initialized by the excited electronic state vibrational trans-bent state ~ A_sp{u}{1 }3_{nu}_3 . The calculations show that with the APS-method we can easily investigate energy regions in the excess of 15,000 cm^{-1}; these high energy regions have been previously unattainable by computational techniques.

  11. Quantum dynamics by the constrained adiabatic trajectory method

    SciTech Connect

    Leclerc, A.; Jolicard, G.; Guerin, S.; Killingbeck, J. P.

    2011-03-15

    We develop the constrained adiabatic trajectory method (CATM), which allows one to solve the time-dependent Schroedinger equation constraining the dynamics to a single Floquet eigenstate, as if it were adiabatic. This constrained Floquet state (CFS) is determined from the Hamiltonian modified by an artificial time-dependent absorbing potential whose forms are derived according to the initial conditions. The main advantage of this technique for practical implementation is that the CFS is easy to determine even for large systems since its corresponding eigenvalue is well isolated from the others through its imaginary part. The properties and limitations of the CATM are explored through simple examples.

  12. Adiabatic regularisation of power spectra in k-inflation

    SciTech Connect

    Alinea, Allan L.; Kubota, Takahiro; Nakanishi, Yukari; Naylor, Wade E-mail: kubota@celas.osaka-u.ac.jp E-mail: naylor@phys.sci.osaka-u.ac.jp

    2015-06-01

    We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll k-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale-invariant power spectra. Furthermore, extending to non-minimal k-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.

  13. Dynamics with the effective adiabatic theory: The Bloch equations

    NASA Astrophysics Data System (ADS)

    Carmeli, Benny; Chandler, David

    1988-07-01

    This paper extends our earlier work on the effective adiabatic theory [J. Chem. Phys. 82, 3400 (1985)] to study relaxation of a two-level system coupled to a Gaussian dissipative bath—the spin-boson problem. Bloch equations are derived which, under the limited circumstances described herein, treat the role of bath fluctuations omitted in the equilibrium effective adiabatic reference system. Applications to the Lorentzian dissipative bath show that the theory agrees closely with numerical simulation results. Application to an Ohmic bath shows that the theory is in agreement with currently accepted results concerned with the problem of macroscopic quantum coherence.

  14. Adiabatic State Conversion and Pulse Transmission in Optomechanical Systems

    NASA Astrophysics Data System (ADS)

    Tian, Lin

    2012-04-01

    Optomechanical systems with strong coupling can be a powerful medium for quantum state engineering of the cavity modes. Here, we show that quantum state conversion between cavity modes of distinctively different wavelengths can be realized with high fidelity by adiabatically varying the effective optomechanical couplings. The conversion fidelity for Gaussian states is derived by solving the Langevin equation in the adiabatic limit. Meanwhile, we also show that traveling photon pulses can be transmitted between different input and output channels with high fidelity and the output pulse can be engineered via the optomechanical couplings.

  15. Gravitational Chern-Simons and the adiabatic limit

    SciTech Connect

    McLellan, Brendan

    2010-12-15

    We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al.[Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.

  16. Vane Flow Direction Sensor for Blast Waves

    DTIC Science & Technology

    1987-02-07

    APPLICATIONS INTL CORP IIT RESEARCH INSTITUTE ATTN: K SITES ATTN: DOCUMENTS LIBRARY SCIENCE APPLICATIONS INTL CORP KAMAN SCIENCES CORP ATTN: TECHNICAL...UBRARY ATTN: L MENTE ATTN: W PLOWS ATTN: LIBRARY SCIENCE APPLICATIONS INTL CORP KAMAN SCIENCE§ CORP ATTN: J MCRARY ATTN: B KINSLOW SCIENCE APPLICATIONS

  17. Fluid Structure Interactions for Blast Wave Mitigation

    DTIC Science & Technology

    2011-05-01

    the flow elds both in front and at the back of the plate are solved using the an Leer flux vector splitting scheme 13,14 coupled with the onotone...directions of characteristic velocity hould be established before the upwind scheme can be imple- ented. The van Leer flux vector splitting scheme is...Anderson, W. K., Thomas, J. L., and Van Leer , B., 1986, “Comparison of Finite Volume Flux Vector Splitting for the Euler Equations,” AIAA J., 249

  18. Analysis of MINIE2013 Explosion Air-Blast Data

    SciTech Connect

    Schnurr, Julie M.; Rodgers, Arthur J.; Kim, Keehoon; Ford, Sean R.; Ramirez, Abelardo L.

    2016-10-14

    We report analysis of air-blast overpressure measurements from the MINIE2013 explosive experiments. The MINIE2013 experiment involved a series of nearly 70 near-surface (height-ofburst, HOB, ranging from -1 to +4 m) low-yield (W=2-20 kg TNT equivalent) chemical highexplosives tests that were recorded at local distances (230 m – 28.5 km). Many of the W and HOB combinations were repeated, allowing for quantification of the variability in air-blast features and corresponding yield estimates. We measured canonical signal features (peak overpressure, impulse per unit area, and positive pulse duration) from the air-blast data and compared these to existing air-blast models. Peak overpressure measurements showed good agreement with the models at close ranges but tended to attenuate more rapidly at longer range (~ 1 km), which is likely caused by upward refraction of acoustic waves due to a negative vertical gradient of sound speed. We estimated yields of the MINIE2013 explosions using the Integrated Yield Determination Tool (IYDT). Errors of the estimated yields were on average within 30% of the reported yields, and there were no significant differences in the accuracy of the IYDT predictions grouped by yield. IYDT estimates tend to be lower than ground truth yields, possibly because of reduced overpressure amplitudes by upward refraction. Finally, we report preliminary results on a development of a new parameterized air-blast waveform.

  19. Relationship between changes in the cochlear blood flow and disorder of hearing function induced by blast injury in guinea pigs

    PubMed Central

    Chen, Wei; Wang, Jianmin; Chen, Jing; Chen, Jichuan; Chen, Zhiqiang

    2013-01-01

    The auditory system is the most susceptible to damages from blast waves. Blast injuries always lead to varying degrees of hearing impairment. Although a disorder of the cochlear blood flow (CoBF) has been considered to be related to many pathological processes of the auditory system and to contribute to various types of hearing loss, changes in the CoBF induced by blast waves and the relationship between such changes and hearing impairment are undefined. To observe the changes in the cochlear microcirculation after exposure to an explosion blast, investigate the relationship between changes in the CoBF and hearing impairment and subsequently explore the mechanism responsible for the changes in the CoBF, we detected the perfusion of the cochlear microcirculation and hearing threshold shift after exposure to an explosion blast. Then, an N-nitro-L-arginine-methyl ester (L-NAME, NO synthase inhibitor) solution and artificial perilymph were applied to the round window (RW) of the cochlea before the blast exposure, followed by an evaluation of the CoBF and hearing function. The results indicated that the changes in the CoBF were correlated to the strength of the blast wave. The cochlear blood flow significantly increased when the peak value of the blast overpressure was greater than approximately 45 kPa, and there was no significant change in the cochlear blood flow when the peak value of the blast overpressure was less than approximately 35 kPa. Following local administration of the NO synthase inhibitor L-NAME, the increase in the CoBF induced by the blast was inhibited, and this reduction was significantly associated with the hearing threshold. PMID:23412965

  20. Cellular Mechanisms and Behavioral Outcomes in Blast-Induced Neurotrauma: Comparing Experimental Setups.

    PubMed

    Bailey, Zachary S; Hubbard, W Brad; VandeVord, Pamela J

    2016-01-01

    Blast-induced neurotrauma (BINT) has increased in incidence over the past decades and can result in cognitive issues that have debilitating consequences. The exact primary and secondary mechanisms of injury have not been elucidated and appearance of cellular injury can vary based on many factors, such as blast overpressure magnitude and duration. Many methodologies to study blast neurotrauma have been employed, ranging from open-field explosives to experimental shock tubes for producing free-field blast waves. While there are benefits to the various methods, certain specifications need to be accounted for in order to properly examine BINT. Primary cell injury mechanisms, occurring as a direct result of the blast wave, have been identified in several studies and include cerebral vascular damage, blood-brain barrier disruption, axonal injury, and cytoskeletal damage. Secondary cell injury mechanisms, triggered subsequent to the initial insult, result in the activation of several molecular cascades and can include, but are not limited to, neuroinflammation and oxidative stress. The collective result of these secondary injuries can lead to functional deficits. Behavioral measures examining motor function, anxiety traits, and cognition/memory problems have been utilized to determine the level of injury severity. While cellular injury mechanisms have been identified following blast exposure, the various experimental models present both concurrent and conflicting results. Furthermore, the temporal response and progression of pathology after blast exposure have yet to be detailed and remain unclear due to limited resemblance of methodologies. This chapter summarizes the current state of blast neuropathology and emphasizes the need for a standardized preclinical model of blast neurotrauma.