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Sample records for air-sf6-air incident shock

  1. The influence of incident shock Mach number on radial incident shock wave focusing

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Tan, Sheng; He, Liming; Rong, Kang; Zhang, Qiang; Zhu, Xiaobin

    2016-04-01

    Experiments and numerical simulations were carried out to investigate radial incident shock focusing on a test section where the planar incident shock wave was divided into two identical ones. A conventional shock tube was used to generate the planar shock. Incident shock Mach number of 1.51, 1.84 and 2.18 were tested. CCD camera was used to obtain the schlieren photos of the flow field. Third-order, three step strong-stability-preserving (SSP) Runge-Kutta method, third-order weighed essential non-oscillation (WENO) scheme and adaptive mesh refinement (AMR) algorithm were adopted to simulate the complicated flow fields characterized by shock wave interaction. Good agreement between experimental and numerical results was observed. Complex shock wave configurations and interactions (such as shock reflection, shock-vortex interaction and shock focusing) were observed in both the experiments and numerical results. Some new features were observed and discussed. The differences of structure of flow field and the variation trends of pressure were compared and analyzed under the condition of different Mach numbers while shock wave focusing.

  2. Investigation of shock focusing in a cavity with incident shock diffracted by an obstacle

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Chen, X.; He, L.-M.; Rong, K.; Deiterding, R.

    2017-03-01

    Experiments and numerical simulations were carried out in order to investigate the focusing of a shock wave in a test section after the incident shock has been diffracted by an obstacle. A conventional shock tube was used to generate the planar shock. Incident shock Mach numbers of 1.4 and 2.1 were tested. A high-speed camera was employed to obtain schlieren photos of the flow field in the experiments. In the numerical simulations, a weighted essentially non-oscillatory (WENO) scheme of third-order accuracy supplemented with structured dynamic mesh adaptation was adopted to simulate the shock wave interaction. Good agreement between experiments and numerical results is observed. The configurations exhibit shock reflection phenomena, shock-vortex interaction and—in particular—shock focusing. The pressure history in the cavity apex was recorded and compared with the numerical results. A quantitative analysis of the numerically observed shock reflection configurations is also performed by employing a pseudo-steady shock transition boundary calculation technique. Regular reflection, single Mach reflection and transitional Mach reflection phenomena are observed and are found to correlate well with analytic predictions from shock reflection theory.

  3. Initiation of detonation by steady planar incident shock waves

    NASA Astrophysics Data System (ADS)

    Edwards, D. H.; Thomas, G. O.; Williams, T. L.

    1981-11-01

    The initiation of detonation by planar shocks is studied in a vertical shock tube in which a removable diaphragm allows the generated shock to be transmitted into the gas mixture, without any reflection at the interface. Streak schlieren photography confirms that a quasi-steady shock reaction complex is formed prior to the shock acceleration phase. The steady phase enabled the induction delay time to be measured in a direct manner, and microwave interferometry, along with pressure transducers, gave an accurate value for the delay time. The shock acceleration was determined from the locus of the exothermic reaction zone, and it is shown that the time coherence of energy release between particles entering the shock front at different times leads to the formation of reactive centers which are characteristic of mild ignition. Ignition delay data obtained by the incident shock method for oxyacetylene, diluted with nitrogen, are compared with those obtained by the reflected shock technique and shown to have advantages in high heat capacity systems.

  4. Time-resolved spectroscopic measurements behind incident and reflected shock waves in air and xenon

    NASA Technical Reports Server (NTRS)

    Yoshinaga, T.

    1973-01-01

    Time-resolved spectra have been obtained behind incident and reflected shock waves in air and xenon at initial pressures of 0.1 and 1.0 torr using a rotating drum spectrograph and the OSU (The Ohio State University) arc-driven shock tube. These spectra were used to determine the qualitative nature of the flow as well as for making estimates of the available test time. The (n+1,n) and (n,n) band spectra of N2(+) (1st negative) were observed in the test gas behind incident shock waves in air at p1=1.0 torr and Us=9-10 km/sec. Behind reflected shock waves in air, the continuum of spectra appeared to cover almost the entire wavelength of 2,500-7,000 A for the shock-heated test gas. For xenon, the spectra for the incident shock wave cases for p1=0.1 torr show an interesting structure in which two intensely bright regions are witnessed in the time direction. The spectra obtained behind reflected shock waves in xenon were also dominated by continuum radiation but included strong absorption spectra due to FeI and FeII from the moment the reflected shock passed and on.

  5. Incident shock-wave characteristics in air, argon, carbon dioxide, and helium in a shock tube with unheated helium driver

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Jones, J. J.

    1975-01-01

    Incident shock-wave velocities were measured in the Langley 6-inch expansion tube, operated as a shock tube, with air, argon, carbon dioxide, and helium as test gases. Unheated helium was used as the driver gas and most data were obtained at pressures of approximately 34 and 54 MN/sq m. A range of pressure ratio across the diaphragm was obtained by varying the quiescent test-gas pressure, for a given driver pressure, from 0.0276 to 34.5 kN/sq m. Single- and double-diaphragm modes of operation were employed and diaphragms of various materials tested. Shock velocity was determined from microwave interferometer measurements, response of pressure transducers positioned along interferometer measurements, response of pressure transducers positioned along the driven section (time-of-arrival gages), and to a lesser extent, measured tube-wall pressure. Velocities obtained from these methods are compared and limitations of the methods discussed. The present results are compared with theory and the effects of diaphragm mode (single or double diaphragm), diaphragm material, heating of the driver gas upon pressurization of the driver section, diaphragm opening time, interface mixing, and two-dimensional (nonplanar) flow are discussed.

  6. Hydrogen film cooling with incident and swept-shock interactions in a Mach 6.4 nitrogen free stream

    NASA Technical Reports Server (NTRS)

    Olsen, George C.; Nowak, Robert J.

    1995-01-01

    The effectiveness of slot film cooling of a flat plate in a Mach 6.4 flow with and without incident and swept oblique shock interactions was experimentally investigated. Hydrogen was the primary coolant gas, although some tests were conducted using helium as the coolant. Tests were conducted in the Calspan 48-Inch Shock Tunnel with a nitrogen flow field to preclude combustion of the hydrogen coolant gas. A two-dimensional highly instrumented model developed in a previous test series was used. Parameters investigated included coolant mass flow rate, coolant gas, local free-stream Reynolds number, incident oblique shock strength, and a swept oblique shock. Both gases were highly effective coolants in undisturbed flow; however, both incident and swept shocks degraded that effectiveness.

  7. Incidence and mortality of sepsis, severe sepsis, and septic shock in intensive care unit patients with candidemia.

    PubMed

    Ng, Kevin; Schorr, Christa; Reboli, Annette C; Zanotti, Sergio; Tsigrelis, Constantine

    2015-08-01

    In this incidence study, of 16 074 patients admitted to the intensive care unit (ICU) from 1/1/2003 to 7/31/2011, 161 cases of candidemia were identified. The incidence of sepsis (27%), severe sepsis (31%), and septic shock (40%) was remarkably high in these cases of candidemia, as was the all-cause in-hospital mortality for sepsis (30%), severe sepsis (44%), and septic shock (65%).

  8. Effects of boundary layer on flame propagation generated by forced ignition behind an incident shock wave

    NASA Astrophysics Data System (ADS)

    Ishihara, S.; Tamura, S.; Ishii, K.; Kataoka, H.

    2016-09-01

    To study the effects of the boundary layer on the deflagration to detonation transition (DDT) process, the mixture behind an incident shock wave was ignited using laser breakdown. Ignition timing was controlled so that the interaction of the resulting flame with a laminar or turbulent boundary layer could be examined. In the case of the interaction with a laminar boundary layer, wrinkling of the flame was observed after the flame reached the corner of the channel. On the other hand, interaction with the turbulent boundary layer distorted the flame front and increased the spreading rate of the flame followed by prompt DDT. The inner structure of the turbulent boundary layer plays an important role in the DDT process. The region that distorted the flame within the turbulent boundary layer was found to be the intermediate region 0.01< y/δ < 0.4, where y is the distance from the wall and δ is the boundary layer thickness. The flame disturbance by the turbulent motions is followed by the flame interaction with the inner layer near the wall, which in turn generates a secondary-ignition kernel that produced a spherical accelerating flame, which ultimately led to the onset of detonation. After the flame reached the intermediate region, the time required for DDT was independent of the ignition position. The effect of the boundary layer on the propagating flame, thus, became relatively small after the accelerating flame was generated.

  9. The Numerical Calculation of Flow Past Conical Bodies Supporting Elliptic Conical Shock Waves at Finite Angles of Incidence

    NASA Technical Reports Server (NTRS)

    Briggs, Benjamin R.

    1960-01-01

    The inverse method, with the shock wave prescribed to be an elliptic cone at a finite angle of incidence, is applied to calculate numerically the supersonic perfect-gas flow past conical bodies not having axial symmetry. Two formulations of the problem are employed, one using a pair of stream functions and the other involving entropy and components of velocity. A number of solutions are presented, illustrating the numerical methods employed, and showing the effects of moderate variation of the initial parameters.

  10. Shock

    MedlinePlus

    ... Many organs can be damaged as a result. Shock requires immediate treatment and can get worse very rapidly. As many 1 in 5 people who suffer shock will die from it. Considerations The main types ...

  11. Shock-absorbing insoles reduce the incidence of lower limb overuse injuries sustained during Royal Marine training.

    PubMed

    House, Carol; Reece, Allyson; Roiz de Sa, Dan

    2013-06-01

    This study was undertaken to determine whether the incidence of lower limb overuse injuries (LLOIs) sustained during Royal Marine training could be reduced by issuing the recruits with shock-absorbing insoles (SAIs) to wear in their military boots. This was a retrospective longitudinal trial conducted in two phases. Injury data from 1,416 recruits issued with standard Saran insoles and 1,338 recruits issued with SAI were compared. The recruits in the two groups were of similar height, body mass, and aerobic fitness and followed the same training course. The incidence of LLOI sustained by the recruits was lower (p < 0.05) in the SAI Group (19.0%) compared to the Saran Insole Group (31.7%). The incidences of lower limb stress fractures, tibial periostitis, tenosynovitis of foot, achilles tendonopathy, other tendonopathy and anterior knee pain were lower (p < 0.05) in the SAI Group. Tibial stress fracture incidence was lower (p < 0.05) in the SAI Group but metatarsal and femoral stress fracture incidences were the same for the two insole groups. Thus, issuing SAIs to military recruits undertaking a sustained, arduous physical training program with a high incidence of LLOI would provide a beneficial reduction in the incidence of LLOI.

  12. Measured pressure distributions, aerodynamic coefficients and shock shapes on blunt bodies at incidence in hypersonic air and CF4

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1982-01-01

    Pressure distributions, aerodynamic coefficients, and shock shapes were measured on blunt bodies of revolution in Mach 6 CF4 and in Mach 6 and Mach 10 air. The angle of attack was varied from 0 deg to 20 deg in 4 deg increments. Configurations tested were a hyperboloid with an asymptotic angle of 45 deg, a sonic-corner paraboloid, a paraboloid with an angle of 27.6 deg at the base, a Viking aeroshell generated in a generalized orthogonal coordinate system, and a family of cones having a 45 deg half-angle with spherical, flattened, concave, and cusp nose shapes. Real-gas effects were simulated for the hperboloid and paraboloid models at Mach 6 by testing at a normal-shock density ratio of 5.3 in air and 12 CF4. Predictions from simple theories and numerical flow field programs are compared with measurement. It is anticipated that the data presented in this report will be useful for verification of analytical methods for predicting hypersonic flow fields about blunt bodies at incidence.

  13. Shock.

    PubMed

    Wacker, David A; Winters, Michael E

    2014-11-01

    Critically ill patients with undifferentiated shock are complex and challenging cases in the ED. A systematic approach to assessment and management is essential to prevent unnecessary morbidity and mortality. The simplified, systematic approach described in this article focuses on determining the presence of problems with cardiac function (the pump), intravascular volume (the tank), or systemic vascular resistance (the pipes). With this approach, the emergency physician can detect life-threatening conditions and implement time-sensitive therapy.

  14. Update through 1985 on the incidence of toxic shock syndrome among members of a prepaid health plan.

    PubMed

    Petitti, D B; Reingold, A L

    1989-01-01

    Through hospital records of men and women aged 15-34 years who were members of the Northern California Kaiser-Permanente Medical Care Program, trends in the incidence of toxic shock syndrome (TSS) requiring hospitalization in 1984-1985 were examined, and the results were compared with those for the period 1972-1983. No definite or probable cases of TSS were found in men during either 1984 or 1985. A total of 16 cases of TSS (10 definite and six probable) were found in women in 1984-1985. Ten (71%) of 14 cases for which the menstrual status of the patient could be determined unambiguously from the medical record occurred during menstruation, and two of the four nonmenstrual cases occurred in postpartum women using barrier contraception. Of the 16 cases, 14 (88%) were diagnosed as TSS or probable TSS by the attending physician, although only nine (64%) of the 14 diagnosed cases were given the correct discharge code. While trends in the incidence of TSS requiring hospitalization in women 15-34 years of age generally paralleled changes in the absorbency of available tampons, the contribution of other factors (e.g., changes in the chemical composition of tampons, changes in patterns of tampon use) to these trends could not be assessed.

  15. Accident investigation of the electrical shock incident at the PG and E PVUSA site Davis, California

    SciTech Connect

    Jacobson, L.; Moskowitz, P.D.; Garrett, J.O.; Tyler, R.

    1992-02-01

    This report summarizes the findings of the Accident Investigation Team (Team) assembled in response to a request from Pacific Gas and Electric Company (PG and E) to the US Department of Energy (DOE) to understand the events surrounding the electric shock of a worker at the PVUSA site in Davis, California and to provide recommendations to prevent such events from recurring. The report gives complete details on the sequence of events surrounding the accident and identifies 27 facts related to accident itself. Four technical deficiencies in the electrical systems which require further investigation were identified. The Team believes that the root cause of this accident was related to the absence of a proactive organizational entity responsible for overall health and safety on the site. Two contributing factors were identified. First, the prototype nature and associated operational difficulties of the electrical inverter resulted in large maintenance demands. Second, several of the injured employee`s co-workers noted that he occasionally failed to use appropriate personal protective equipment, but they never reported this practice to management. The direct cause of this accident was the failure of the injured employee to wear appropriate personal protective equipment (i.e., rubber gloves). Based on the review of the facts established in this investigation, five recommendations are presented to the funding agencies to reduce the possibility of future accidents at the PVUSA site.

  16. Computer Program for Calculation of Complex Chemical Equilibrium Compositions, Rocket Performance, Incident and Reflected Shocks, and Chapman-Jouguet Detonations. Interim Revision, March 1976

    NASA Technical Reports Server (NTRS)

    Gordon, S.; Mcbride, B. J.

    1976-01-01

    A detailed description of the equations and computer program for computations involving chemical equilibria in complex systems is given. A free-energy minimization technique is used. The program permits calculations such as (1) chemical equilibrium for assigned thermodynamic states (T,P), (H,P), (S,P), (T,V), (U,V), or (S,V), (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. The program considers condensed species as well as gaseous species.

  17. Incidence, risk factors and impact on outcomes of secondary infection in patients with septic shock: an 8-year retrospective study

    PubMed Central

    Zhao, Guang-ju; Li, Dong; Zhao, Qian; Song, Jia-xing; Chen, Xiao-rong; Hong, Guang-liang; Li, Meng-fang; Wu, Bing; Lu, Zhong-qiu

    2016-01-01

    Secondary infection in septic patients has received widespread attention, although clinical data are still lacking. The present study was performed on 476 patients with septic shock. Time trends for mortality were analyzed using Spearman’s rank correlation test. Risk factors for secondary infection were investigated by binary logistic regression. The extended Cox model with time-varying covariates and hazard ratios (HR) was performed to determine the impact of secondary infection on mortality. Differences in hospital length of stay (LOS) between patients with and without secondary infection were calculated using a multistate model. Thirty-nine percent of septic shock patients who survived the early phase of the disease developed secondary infection. There was a statistically significant increased odds ratio for secondary infection in older patients and patients with a longer LOS in the intensive care unit (ICU), a higher Sequential Organ Failure Assessment (SOFA) score, and endotracheal intubation. Secondary infection significantly reduced the rate of discharge (HR 5.607; CI95 3.612–8.704; P < 0.001) and was associated with an increased hospital LOS of 5.46 days. The present findings represent a direct description of secondary infection in septic shock patients and highlight the influence of this condition on septic shock outcomes. PMID:27924831

  18. Measured and predicted shock shapes and aerodynamic coefficients for blunted cones at incidence in helium at Mach 20.3

    NASA Technical Reports Server (NTRS)

    Calloway, R. L.; White, N. H.

    1979-01-01

    Experimental values of shock shapes (alpha = 0 degrees and 10 degrees) and static aerodynamic coefficients (alpha = -4 degrees to 12 degrees) for sharp and spherically blunted cones having cone half-angles of 30, 45, 60, and 70 degrees and nose bluntness ratios of 0, 0.25, and 0.50 are presented. Shock shapes were also measured at 0 degree angle of attack by using a flat-faced cylinder (90 degree cone) and a hemispherically blunted cylinder (sphere). All tests were conducted in helium (gamma = 5/3) at a free-stream Mach number of 20.3 and a unit free-stream Reynolds number of 22,400,000 per meter. Comparisons between measured values and predicted values were made by using several numerical and simple engineering methods.

  19. Measured and predicted shock shapes and aerodynamic coefficients for blunted cones at incidence in air at Mach 5.9

    NASA Technical Reports Server (NTRS)

    Calloway, R. L.; White, N. H.

    1980-01-01

    Experimental values of shock shapes (angles of attack of 0 deg and 10 deg) and static aerodynamic coefficients (angles of attack of -4 deg to 12 deg for sharp and spherically blunted cones having cone half angles of 30 deg, 45 deg, 60 deg, and 70 deg, and nose bluntness ratios of 0, 0.25, and 0.50 are presented. Shock shapes were measured at 0 deg angle of attack by using a flat faced cylinder (90 deg cone) and a hemispherically blunted cylinder (sphere). All tests were conducted in air at a free stream Mach number of 5.9 and a unit free stream Reynolds number of 2,800,000 per meter. Comparisons between measured values and predicted values were made by using several numerical and simple engineering methods.

  20. Plasma antibodies against heat shock protein 70 correlate with the incidence and severity of asthma in a Chinese population

    PubMed Central

    Yang, Miao; Wu, Tangchun; Cheng, Longxian; Wang, Feng; Wei, Qingyi; Tanguay, Robert M

    2005-01-01

    Background The heat shock proteins (Hsps) are induced by stresses such as allergic factors and inflammatory responses in bronchi epithelial cells and therefore may be detectable in patients with asthma. However, the etiologic link between anti-Hsps and asthma (its severity and related inflammatory responses such as interleukin-4 and immunoglobulin E) has not been established. We determined whether antibodies against Hsp60 and Hsp70 were present in patients with asthma and evaluated their associations with risk and severity of asthma. Methods We determined the levels of anti-Hsp60 and anti-Hsp70 by immunoblot and their associations with risk and symptom severity of asthma in 95 patients with asthma and 99 matched non-symptomatic controls using multivariate logistic regression analysis. Results Compared to the controls, asthma patients were more likely to have detectable anti-Hsp60 (17.2% vs 5.1%) and anti-Hsp70 (33.7% vs 8.1%) (p ≤ 0.001). In particular, the presence of anti-Hsp70 was associated with a greater than 2 fold risk for asthma (adjusted OR = 2.21; 95% CI = 1.35~3.59). Furthermore, both anti-Hsp60 and anti-Hsp70 levels were positively correlated with symptom severity (p < 0.05) as well as interleukin-4 and immunoglobulin E (p < 0.05). Individuals with antibodies against anti-Hsp60 and anti-Hsp70 were more likely to have a family history of asthma (p < 0.001) and higher plasma concentrations of total immunoglobulin E (p = 0.001) and interleukin-4 (p < 0.05) than those without antibodies. Conclusions These data suggest that anti-Hsp60 and especially anti-Hsp70 correlate with the attacks and severity of asthma. The underlying molecular mechanisms linking antibodies to heat shock proteins and asthma remain to be investigated. PMID:15710045

  1. Long-term incidence and risk factors for recurrent stones following percutaneous nephrostolithotomy or percutaneous nephrostolithotomy/extracorporeal shock wave lithotripsy for infection related calculi.

    PubMed

    Streem, S B

    1995-03-01

    A study was done to determine the long-term incidence and cause of recurrent stones following percutaneous nephrostolithotomy alone (13 patients) or combined with extracorporeal shock wave lithotripsy (31) for management of documented infection related struvite renal calculi. The patients were followed for 12 to 111 months (mean 41.7) to censorship or time of new stone formation. Of these patients 12 (27%) had recurrent stones at 12 to 61 months (mean 32.3) after treatment. As determined by a Kaplan-Meier estimate, the risk of new stone formation 5 years after treatment was 36.8%. Potential risk factors for recurrence, including history of stones, associated anatomical abnormalities, procedure used, radiographic status at completion of treatment and recurrent infection during followup, were analyzed with Cox's proportional hazards model. Of these potential risk factors, only an associated anatomical abnormality was found to influence significantly the rate of recurrent stone formation (p = 0.005). We conclude that continued surveillance for recurrent stones is mandatory even for patients initially rendered stone-free and those who maintain sterile urine. In addition, because the presence of a significant anatomical or functional urinary tract abnormality places a patient at much higher risk for recurrence, we suggest that subsequent studies be stratified as to the presence or absence of these abnormalities.

  2. Shock/shock interference on a transpiration cooled hemispherical model

    NASA Technical Reports Server (NTRS)

    Nowak, Robert J.; Wieting, Allan R.; Holden, Michael S.

    1990-01-01

    Experimental results are presented which show the effectiveness of transpiration cooling in reducing the peak heat flux caused by an impinging shock on a bow shock of a hemispherical model. The 12-inch diameter hemispherical transpiration model with helium coolant was tested in the Calspan 48-inch Hypersonic Shock Tunnel at nominal Mach 12.1 and freestream unit Reynolds number of 0.33 x 10 to the 6th/ft. An incident shock wave, generated by a blunt flat-plate shock generator inclined at 10 deg to the freestream, intersected the bow shock of the model to produce shock/shock interference. The stagnation heat flux without coolant or shock/shock interference was about 1.6 times a smooth surface laminar prediction due to effective roughness of the coolant ejection slots. A coolant mass flux 31 percent of the freestream mass flux reduced the stagnation heat flux to zero without shock/shock interference. However, for the same coolant mass flux and with shock/shock interference the peak heat flux was only reduced 8.3 percent, even though the total integrated heat load was reduced.

  3. When shock waves collide

    SciTech Connect

    Martinez, D.; Hartigan, P.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Foster, J.; Wilde, B.; Blue, B.; Rosen, P.; Farley, D.; Paguio, R.

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed to quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.

  4. When shock waves collide

    DOE PAGES

    Martinez, D.; Hartigan, P.; Frank, A.; ...

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

  5. Ion reflection and dissipation at quasi-parallel collisionless shocks

    NASA Astrophysics Data System (ADS)

    Scholer, Manfred; Terasawa, Toshio

    1990-02-01

    Large scale one-dimensional hybrid simulations have been performed of a quasi-parallel high Mach number collisionless shock. It is found that backstreaming reflected ions, i.e., upstream ions with velocities exceeding the shock ram velocity, originate from the outer part of the velocity space of the incident distribution. The backstreaming ions produce very low-frequency magnetosonic waves which propagate upstream with about 1.3 Alfven speed. As the wave crests convect toward the shock, they steepen up the shock reforms itself. During shock reformation a large part of the incident ions are reflected. This, in turn, slows the incident ions down. The slowed down incident particle distribution and the reflected particle distribution merge and constitute the new thermalized downstream distribution. In the interval of a relatively stationary shock low-frequency whistler waves stand at the shock front. During these time intervals, the whistler waves are probably responsible for dissipation by nonadiabatic compression of the incident ions.

  6. [Severe sepsis and septic shock].

    PubMed

    Tønnesen, Else; Larsen, Kim

    2014-07-07

    Sepsis, severe sepsis and septic shock are syndromes. The incidence of sepsis is as high as 35% and with mortality rates in the intensive care unit from 27% to 54% in sepsis and septic shock, respectively. Many new treatments have been tested but only few have been implemented in clinical practise. The treatment of severe sepsis and septic shock is based on the Surviving Sepsis Campaign guidelines developed by an international expert panel. Early diagnosis, optimization of haemodynamics, rapid identification of focus and adequate antibiotic treatment are the most important strategies.

  7. Septic Shock

    PubMed Central

    Lansing, Allan M.

    1963-01-01

    Septic shock may be defined as hypotension caused by bacteremia and accompanied by decreased peripheral blood flow, evidenced by oliguria. Clinically, a shaking chill is the warning signal. The immediate cause of hypotension is pooling of blood in the periphery, leading to decreased venous return: later, peripheral resistance falls and cardiac failure may occur. Irreversible shock is comparable to massive reactive hyperemia. Reticuloendothelial failure, histamine release, and toxic hypersensitivity may be factors in the pathogenesis of septic shock. Adrenal failure does not usually occur, but large doses of corticosteroid are employed therapeutically to counteract the effect of histamine release or hypersensitivity to endotoxin. The keys to successful therapy are time, antibiotics, vasopressors, cortisone and correction of acidosis. PMID:14063936

  8. Laser Light Scattering by Shock Waves

    NASA Technical Reports Server (NTRS)

    Panda, J.; Adamovsky, G.

    1995-01-01

    Scattering of coherent light as it propagates parallel to a shock wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the shock containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow shock the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.

  9. [Critical incidents].

    PubMed

    Scheidegger, D

    2005-03-01

    In medicine real severe mishaps are rare. On the other hand critical incidents are frequent. Anonymous critical incident reporting systems allow us to learn from these mishaps. This learning process will make our daily clinical work safer Unfortunately, before these systems can be used efficiently our professional culture has to be changed. Everyone in medicine has to admit that errors do occur to see the need for an open discussion. If we really want to learn from errors, we cannot punish the individual, who reported his or her mistake. The interest is primarily in what has happened and why it has happened and not who has committed this mistake. The cause for critical incidents in medicine is in over 80% the human factor Poor communication, work under enormous stress, conflicts and hierarchies are the main cause. This has been known for many years, therefore have already 15 years ago high-tech industries, like e.g. aviation, started to invest in special courses on team training. Medicine is a typical profession were until now only the individual performance decided about the professional career Communication, conflict management, stress management, decision making, risk management, team and team resource management were subjects that have never been taught during our preor postgraduate education. These points are the most important ones for an optimal teamwork. A multimodular course designed together with Swissair (Human Aspect Development medical, HADmedical) helps to cover, as in aviation, the soft factor and behavioural education in medicine and to prepare professionals in health care to work as a real team.

  10. Sepsis and Septic Shock: Lingering Questions.

    PubMed

    Dumont, Tiffany; Francis-Frank, Lyndave; Chong, Josebelo; Balaan, Marvin R

    2016-01-01

    Sepsis and septic shock are major health conditions in the United States, with a high incidence and mortality. The Surviving Sepsis Campaign, which was formed in 2002, formulates guidelines for the management of severe sepsis and septic shock and has actually demonstrated a reduction in mortality with institution of "sepsis bundles." Despite this, some elements of the guidelines have been questioned, and recent data suggest that strict compliance with bundles and protocols may not be necessary. Still, prompt recognition and treatment of sepsis and septic shock remain of utmost importance.

  11. Multiple shocks

    NASA Astrophysics Data System (ADS)

    Shenker, Stephen H.; Stanford, Douglas

    2014-12-01

    Using gauge/gravity duality, we explore a class of states of two CFTs with a large degree of entanglement, but with very weak local two-sided correlation. These states are constructed by perturbing the thermofield double state with thermal-scale operators that are local at different times. Acting on the dual black hole geometry, these perturbations create an intersecting network of shock waves, supporting a very long wormhole. Chaotic CFT dynamics and the associated fast scrambling time play an essential role in determining the qualitative features of the resulting geometries.

  12. Quasi-perpendicular shocks: Length scale of the cross-shock potential, shock reformation, and implication for shock surfing

    NASA Astrophysics Data System (ADS)

    Scholer, Manfred; Shinohara, Iku; Matsukiyo, Shuichi

    2003-01-01

    One-dimensional (1-D) full particle simulations of almost perpendicular supercritical collisionless shocks are presented. The ratio of electron plasma frequency ωpe to gyrofrequency Ωce, the ion to electron mass ratio, and the ion and electron β (β = plasma to magnetic field pressure) have been varied. Due to the accumulation of specularly reflected ions upstream of the shock, ramp shocks can reform on timescales of the gyroperiod in the ramp magnetic field. Self-reformation is not a low ωpe/Ωce process but occurs also in (ωpe/Ωce)2 ≫ 1, low β simulations. Self-reformation also occurs in low ion β runs with an ion to electron mass ratio mi/me = 1840. However, in the realistic mass ratio runs, an electromagnetic instability is excited in the foot of the shock, and the shock profile is considerably changed compared to lower mass ratio runs. Linear analysis based on three-fluid theory (incident ions, reflected ions, and electrons) indicates that the instability is a modified two-stream instability between the decelerated solar wind electrons and the solar wind ions on the whistler mode branch. In the reforming low ion β shocks, part of the potential drop occurs at times across the foot, and part of the potential (˜40%) occurs over a few (˜4) electron inertial lengths in the steepened up ramp. Self-reformation is a low ion β process and disappears for a Mach 4.5 shock at/or above βi ≈ 0.4. It is argued that the ion thermal velocity has to be an order of magnitude smaller than the shock velocity in order for reformation to occur. Since according to these simulations only part of the potential drop occurs for relatively short times over a few electron inertial lengths, it is concluded that coherent shock surfing is not an efficient acceleration mechanism for pickup ions at the low β heliospheric termination shock.

  13. Analysis of shock-wave propagation in aqueous foams using shock tube experiments

    NASA Astrophysics Data System (ADS)

    Jourdan, G.; Mariani, C.; Houas, L.; Chinnayya, A.; Hadjadj, A.; Del Prete, E.; Haas, J.-F.; Rambert, N.; Counilh, D.; Faure, S.

    2015-05-01

    This paper reports experimental results of planar shock waves interacting with aqueous foams in a horizontal conventional shock tube. Four incident shock wave Mach numbers are considered, ranging from 1.07 to 1.8, with two different foam columns of one meter thickness and expansion ratios of 30 and 80. High-speed flow visualizations are used along with pressure measurements to analyse the main physical mechanisms that govern shock wave mitigation in foams. During the shock/foam interaction, a precursor leading pressure jump was identified as the trace of the liquid film destruction stage in the foam fragmentation process. The corresponding pressure threshold is found to be invariant for a given foam. Regarding the mitigation effect, the results show that the speed of the shock is drastically reduced and that wetter is the foam, slower are the transmitted waves. The presence of the foam barrier attenuates the induced pressure impulse behind the transmitted shock, while the driest foam appears to be more effective, as it limits the pressure induced by the reflected shock off the foam front. Finally, it was found that the pressure histories in the two-phase gas-liquid mixture are different from those previously obtained within a cloud of droplets. The observed behavior is attributed to the process of foam fragmentation and to the modification of the flow topology past the shock. These physical phenomena occurring during the shock/foam interaction should be properly accounted for when elaborating new physical models.

  14. Shock Prevention

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  15. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the shock front advancing through the sample, thereby minimizing adverse effects of refraction.

  16. Measurement of the shock front velocity produced in a T-tube

    SciTech Connect

    Djurović, S.; Mijatović, Z.; Vujičić, B.; Kobilarov, R.; Savić, I.; Gavanski, L.

    2015-01-15

    A set of shock front velocity measurements is described in this paper. The shock waves were produced in a small electromagnetically driven shock T-tube. Most of the measurements were performed in hydrogen. The shock front velocity measurements in other gases and the velocity of the gas behind the shock front were also analyzed, as well as the velocity dependence on applied input energy. Some measurements with an applied external magnetic field were also performed. The used method of shock front velocity is simple and was shown to be very reliable. Measured values were compared with the calculated ones for the incident and reflected shock waves.

  17. Geometrical shock dynamics of fast magnetohydrodynamic shocks

    NASA Astrophysics Data System (ADS)

    Mostert, Wouter; Pullin, Dale I.; Samtaney, Ravi; Wheatley, Vincent

    2016-11-01

    We extend the theory of geometrical shock dynamics (GSD, Whitham 1958), to two-dimensional fast magnetohydrodynamic (MHD) shocks moving in the presence of nonuniform magnetic fields of general orientation and strength. The resulting generalized area-Mach number rule is adapted to MHD shocks moving in two spatial dimensions. A partially-spectral numerical scheme developed from that of Schwendeman (1993) is described. This is applied to the stability of plane MHD fast shocks moving into a quiescent medium containing a uniform magnetic field whose field lines are inclined to the plane-shock normal. In particular, we consider the time taken for an initially planar shock subject to an initial perturbed magnetosonic Mach number distribution, to first form shock-shocks. Supported by KAUST OCRF Award No. URF/1/2162-01.

  18. Shock wave interactions with liquid sheets

    NASA Astrophysics Data System (ADS)

    Jeon, H.; Eliasson, V.

    2017-04-01

    Shock wave interactions with a liquid sheet are investigated by impacting planar liquid sheets of varying thicknesses with a planar shock wave. A square frame was designed to hold a rectangular liquid sheet, with a thickness of 5 or 10 mm, using plastic membranes and cotton wires to maintain the planar shape and minimize bulge. The flat liquid sheet, consisting of either water or a cornstarch and water mixture, was suspended in the test section of a shock tube. Incident shock waves with Mach numbers of M_s = 1.34 and 1.46 were considered. A schlieren technique with a high-speed camera was used to visualize the shock wave interaction with the liquid sheets. High-frequency pressure sensors were used to measure wave speed, overpressure, and impulse both upstream and downstream of the liquid sheet. Results showed that no transmitted shock wave could be observed through the liquid sheets, but compression waves induced by the shock-accelerated liquid coalesced into a shock wave farther downstream. A thicker liquid sheet resulted in a lower peak overpressure and impulse, and a cornstarch suspension sheet showed a higher attenuation factor compared to a water sheet.

  19. Structure, Shape and Movement of the Termination Shock

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron; Morrison, David (Technical Monitor)

    1994-01-01

    In this paper we review current ideas concerning the morphology and dynamics of the heliospheric termination shock. The mean distance of the shock is expected to lie somewhere in the range 50-200 AU, and should vary with latitude, depending on mean latitude variation of the dynamical pressure of the solar wind. The shock is expected to move in response to variation in upstream solar wind conditions, so that at any particular instant the termination shock will resemble a distorted asymmetric balloon with some parts moving inward and others moving outward. The simplest model of the shock is that of an infinitely thin gasdynamic or magnetohydrodynamic shock wave, which moves inward or outward at speeds of approximately 100 kilometers per second. The structure and motion of the shock will be strongly modified if an appreciable fraction of the incident solar wind energy goes into acceleration of energetic particles, specifically the anomalous cosmic rays.

  20. Gigabar Spherical Shock Generation on the OMEGA Laser

    SciTech Connect

    Nora, R.; Theobald, W.; Betti, R.; Marshall, F. J.; Michel, D. T.; Seka, W.; Yaakobi, B.; Lafon, M.; Stoeckl, C.; Delettrez, J.; Solodov, A. A.; Casner, A.; Reverdin, C.; Ribeyre, X.; Vallet, A.; Peebles, J.; Beg, F. N.; Wei, M. S.

    2015-01-01

    This Letter presents the first experimental demonstration of the capability to launch shocks of several hundred Mbar in spherical targets - a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using the temporal delay between the launching of the strong shock at the outer surface of the spherical target and the time when the shock converges at the center, the shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures exceeding 300 Mbar are inferred at absorbed laser intensities of ~3 × 1015 W/cm2. The shock strength is shown to be significantly enhanced by the coupling of suprathermal electrons with a total converted energy of up to 8% of the incident laser energy. At the end of the laser pulse, the shock pressure is estimated to exceed ~1 Gbar because of convergence effects.

  1. Effects of Fin Leading Edge Sweep on Shock-Shock Interaction at Mach 6

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.

    1996-01-01

    The effects of fin leading edge sweep on peak heating rates due to shock-shock interaction have been experimentally examined in the Langley 20-Inch Mach 6 Tunnel. The shock interaction was produced by the intersection of a planar incident shock (16.8 deg shock angle relative to the freestream, generated by a 9 deg wedge) with the bow shock formed around a O.5-inch diameter cylindrical leading edge fin. Heating distributions along the leading edge stagnation line have been obtained using densely spaced thin film resistive-type sensors. Schlieren images were obtained to illustrate the very complex shock-shock interactions. The fin leading edge sweep angle was varied from 15-degrees swept back to 45-degrees swept forward for a freestream unit Reynolds number of 2 x 10(exp 6)/ft. Two models were utilized during the study, one with 0.025-inch spacing between gage centers, and the other 0.015-inch spacing. Gage spatial resolution on the order of 0.015-in appeared to accurately capture the narrow spike in heating. Peak heating due to shock interaction was maximized when the fin was swept forward 15 deg and 25 deg, both promoting augmentations about 7 times the baseline value. The schlieren images for these cases revealed Type 4 and Type 3 interactions, respectively.

  2. Toxic Shock Syndrome

    MedlinePlus

    ... burn to avoid getting a staph infection. Toxic shock syndrome treatment Because toxic shock syndrome gets worse quickly, you may be seriously ... toxic shock syndrome in a wound? Resources Toxic Shock Syndrome ... treatment, women's health Family Health, Women January 2017 Copyright © ...

  3. A Theoretical Basis for the Scaling Law of Broadband Shock Noise Intensity in Supersonic Jets

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2011-01-01

    A theoretical basis for the scaling of broadband shock noise intensity In supersonic jets was formulated considering linear shock-shear wave interaction. Modeling of broadband shock noise with the aid of shock-turbulence interaction with special reference to linear theories is briefly reviewed. An hypothesis has been postulated that the peak angle of incidence (closer to the critical angle) for the shear wave primarily governs the generation of sound in the interaction process with the noise generation contribution from off-peak incident angles being relatively unimportant. The proposed hypothesis satisfactorily explains the well-known scaling law for the broadband shock-associated noise in supersonic jets.

  4. Studies of aerothermal loads generated in regions of shock/shock interaction in hypersonic flow

    NASA Technical Reports Server (NTRS)

    Holden, Michael S.; Moselle, John R.; Lee, Jinho

    1991-01-01

    Experimental studies were conducted to examine the aerothermal characteristics of shock/shock/boundary layer interaction regions generated by single and multiple incident shocks. The presented experimental studies were conducted over a Mach number range from 6 to 19 for a range of Reynolds numbers to obtain both laminar and turbulent interaction regions. Detailed heat transfer and pressure measurements were made for a range of interaction types and incident shock strengths over a transverse cylinder, with emphasis on the 3 and 4 type interaction regions. The measurements were compared with the simple Edney, Keyes, and Hains models for a range of interaction configurations and freestream conditions. The complex flowfields and aerothermal loads generated by multiple-shock impingement, while not generating as large peak loads, provide important test cases for code prediction. The detailed heat transfer and pressure measurements proved a good basis for evaluating the accuracy of simple prediction methods and detailed numerical solutions for laminar and transitional regions or shock/shock interactions.

  5. Prospective, consecutive case series of 158 snakebite patients treated at Savannakhet provincial hospital, Lao People's Democratic Republic with high incidence of anaphylactic shock to horse derived F(ab')2 antivenom.

    PubMed

    Vongphoumy, Inthanomchanh; Chanthilat, Phankham; Vilayvong, Phongmany; Blessmann, Joerg

    2016-07-01

    Snakebites are a seriously neglected public health problem in Lao PDR. Community-based cross-sectional surveys in two districts of Savannakhet province in Southern Laos revealed an incidence of up to 1105 snakebites per 100,000 persons per year. In contrast the number of snakebite patients treated in district and provincial hospitals are low. In order to improve health care for snakebite victims, antivenom was introduced to Savannakhet provincial hospital in July 2013 and medical staff has been trained in management of venomous snakebites at the same time. After the intervention the number of snakebite patients treated at the provincial hospital increased significantly from 4 patients in 2012 to 158 snakebite patients between July 2013 and November 2015. They were included into a prospective, consecutive case series. Median age was 32 years (range 1.5-70 years) and male-to-female ratio 2.2:1. Forty patients were bitten by Malayan pit vipers, 26 by green pit vipers, 24 by cobras, including 3 cases of venom ophthalmia, 5 by kraits, 8 by non-venomous species and in 55 cases the snake could not be identified. Forty-three out of 158 patients received horse derived F(ab')2 antivenom from Queen Saovabha Memorial Institute (QSMI) in Bangkok. Twenty-three patients (53%) developed early adverse reactions (EARs) within one hour after antivenom administration, including 13 patients (30%) with severe anaphylaxis. This extremely high rate of severe EARs turns the use of antivenom into a risky intervention. In contrast a retrospective chart review from Chulalongkorn University in Bangkok found only 3.5% early reactions including 1.2% severe anaphylactic reactions using the same antivenom from QSMI between 1997 and 2006. The reason for this enormous difference remains unclear. A better understanding of the aetiology and pathophysiology behind antivenom induced anaphylaxis is crucial in order to identify patients at risk and to improve safety of antivenom administration.

  6. Inlet boundary conditions for shock wave propagation problems in air ducts

    NASA Astrophysics Data System (ADS)

    Fashbaugh, R. H.

    1992-03-01

    Shock waves propagating into air ducting systems are numerically studied using data from Kriebel (1972). Small-scale junctions mounted in shock tubes with an incident shock wave are considered. The stagnation pressure ratio through a duct inlet is evaluated for various junction types. The logarithm of this ratio varies linearly with the Mach number of the flow behind the incident shock wave. The static pressure inside the inlet is established using experimental data with given Mach numbers of the incident and inlet flows. A constant stagnation enthalpy through the inlet junction is assumed to establish inflow to the duct.

  7. Radiative Shock Waves In Emerging Shocks

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul; Doss, F.; Visco, A.

    2011-05-01

    In laboratory experiments we produce radiative shock waves having dense, thin shells. These shocks are similar to shocks emerging from optically thick environments in astrophysics in that they are strongly radiative with optically thick shocked layers and optically thin or intermediate downstream layers through which radiation readily escapes. Examples include shocks breaking out of a Type II supernova (SN) and the radiative reverse shock during the early phases of the SN remnant produced by a red supergiant star. We produce these shocks by driving a low-Z plasma piston (Be) at > 100 km/s into Xe gas at 1.1 atm. pressure. The shocked Xe collapses to > 20 times its initial density. Measurements of structure by radiography and temperature by several methods confirm that the shock wave is strongly radiative. We observe small-scale perturbations in the post-shock layer, modulating the shock and material interfaces. We describe a variation of the Vishniac instability theory of decelerating shocks and an analysis of associated scaling relations to account for the growth of these perturbations, identify how they scale to astrophysical systems such as SN 1993J, and consider possible future experiments. Collaborators in this work have included H.F. Robey, J.P. Hughes, C.C. Kuranz, C.M. Huntington, S.H. Glenzer, T. Doeppner, D.H. Froula, M.J. Grosskopf, and D.C. Marion ________________________________ * 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.

  8. Effect of strong thermalization on shock dynamical behavior

    NASA Astrophysics Data System (ADS)

    Shimada, Nobue; Hoshino, Masahiro

    2005-02-01

    The dynamics of the perpendicular shock front is examined under various plasma parameters by using particle-in-cell numerical simulation. As widely accepted, above the critical Mach number (˜3) the front of (quasi-)perpendicular shocks show nonstationary behavior due to the shock self-reformation. In much higher Mach number regime (MA > 20), we find that dynamics of the shock front self-reformation can be modified. Nonlinear evolution of microinstabilities in the shock transition region results turbulent profiles in a microscopic view (≤c/ωpe), while, from a macroscopic view (>several c/ωpe) because of rapid, strong thermalization in the shock transition region, the localized accumulation of the plasma due to ion dynamics is smeared out in both of the velocity phase space and real space. As a result, the shock self-reformation is realized within a reduced time and space. We can say there is a possibility that rapid, strong dissipation helps to stabilize the macroscopic shock front dynamics; the shock self-reformation still persists, though. The strong thermalization is caused by the nonlinear evolution of two-stream instability between the electron and the reflected/incident ion components and following ion-acoustic instability. We think that the modification of the shock self-reformation process observed in high Mach number regime indicates an important role of electron kinetics and heating in the macroscopic shock front behavior.

  9. Boundaries of the ambiguity area upon reflection of compression shock waves

    NASA Astrophysics Data System (ADS)

    Bulat, P. V.; Upyrev, V. V.

    2016-01-01

    Oblique shock waves can be reflected from hard walls, the axis, or the plane of symmetry, as well as from other counterpropagating shock waves with the formation of regular and Mach shock wave configurations. The specific form of shock wave structures is determined by the parameters of the problem: Mach number and intensity of incident shock waves. On the plane of parameters, there exists an ambiguity area in which laws of conservation admit both the regular and Mach reflection of shock waves. The boundaries of this region have been determined.

  10. Introduction to Pesticide Incidents

    EPA Pesticide Factsheets

    Pesticides incidents must be reported by pesticide registrants. Others, such as members of the public and environmental professionals, would like to report pesticide incidents. This website will explain and facilitate such incident reporting.

  11. Ion heating and energy redistribution across supercritical perpendicular shocks: Application to planetary and interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Liu, Y. D.; Richardson, J. D.; Parks, G. K.

    2013-12-01

    We investigate how the ion dissipative process across supercritical perpendicular shocks depends on the shock front micro-structures. At a collisionless plasma shock, the dissipation and micro-structure of the shock font are dominated by wave-particle interactions. Comparison of the ion thermalization at different kinds of shocks, e.g., planetary and interplanetary shocks, can quantify how much interaction is occurring at the shock boundary. Investigation of this problem for diverse solar wind (SW) conditions will yield important information on the dependences of the ion thermalization and energy redistribution on plasma parameters. With the aid of a successful automatic separation method [Yang et al., 2009], the incident ions at the shock can be divided into two parts: reflected (R) ions and directly transmitted (DT) ions. Corresponding heating efficiency of each population of ions at the shock can be calculated respectively. Wilkinson & Schwartz [1990] have theorized that the amount of reflected ions at perpendicular shocks depends on plasma parameters. Based on the Rankine-Hugoniot (R-H) conservation laws, they found that the fraction reflected is strongly dependent on the magnitude of the ratio of specific heat capacities γ chosen in the R-H relations. The main goal of this work is to investigate how the plasma parameters, e.g. the particle velocity distribution, the plasma beta value, seed populations, etc. (from a particle dynamic point of view), control the amount of reflected ions by using one-dimensional (1-D) full-particle-cell simulations. The simulation results may help to explain the ion heating efficiency and energy redistribution at shocks observed by Cluster, Wind, Voyager, etc.

  12. How Is Cardiogenic Shock Diagnosed?

    MedlinePlus

    ... from the NHLBI on Twitter. How Is Cardiogenic Shock Diagnosed? The first step in diagnosing cardiogenic shock ... is cardiogenic shock. Tests and Procedures To Diagnose Shock and Its Underlying Causes Blood Pressure Test Medical ...

  13. Toxic Shock Syndrome

    MedlinePlus

    ... toxic shock syndrome results from toxins produced by Staphylococcus aureus (staph) bacteria, but the condition may also ... a skin or wound infection. Bacteria, most commonly Staphylococcus aureus (staph), causes toxic shock syndrome. It can ...

  14. Neptune inbound bow shock

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Lepping, Ronald P.

    1995-01-01

    Voyager 2 crossed the inbound or upstream Neptunian bow shock at 1430 spacecraft event time on August 24 in 1989 (Belcher et al., 1989). The plasma and magnetic field measurements allow us to study the solar wind interaction with the outermost gas giant. To fully utilize all of the spacecraft observations, an improved nonlinear least squares, 'Rankine-Hugoniot' magnetohydrodynamic shock-fitting technique has been developed (Szabo, 1994). This technique is applied to the Neptunian data set. We find that the upstream bow shock normal points nearly exactly toward the Sun consistent with any reasonable large-scale model of the bow shock for a near subsolar crossing. The shock was moving outward with a speed of 14 +/- 12 km/s. The shock can be characterized as a low beta, high Mach number, strong quasi-perpendicular shock. Finally, the shock microstructure features are resolved and found to scale well with theoretical expectations.

  15. Shock & Anaphylactic Shock. Learning Activity Package.

    ERIC Educational Resources Information Center

    Hime, Kirsten

    This learning activity package on shock and anaphylactic shock is one of a series of 12 titles developed for use in health occupations education programs. Materials in the package include objectives, a list of materials needed, information sheets, reviews (self evaluations) of portions of the content, and answers to reviews. These topics are…

  16. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, D.S.; Schmidt, S.C.

    1984-02-21

    A method is disclosed for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the stock front advancing through the sample, thereby minimizing adverse effects of refraction.

  17. Viscous hypersonic shock-shock interaction on a blunt body at high altitude

    NASA Technical Reports Server (NTRS)

    Comeaux, Keith A.; Chapman, Dean R.; Maccormack, Robert W.

    1993-01-01

    The shock interaction produced when an incident oblique shock impinges on a blunt body, such as an engine inlet cowl lip of a hypersonic vehicle, is investigated for high altitude flight conditions. A perfect gas, Navier-Stokes numerical simulation of this problem at various altitudes representing continuum through transitional conditions is performed using the modified flux vector splitting method of Steger and Warming (1979). Two series of solutions are produced. First, a number-of-shock-positions are studied at a particular altitude and Mach number. Second, given a fixed shock position and Mach number, the interaction is investigated at several altitudes ranging from continuum to transitional flow conditions. It is shown that the interaction becomes fundamentally different as the density is lowered, and its effect on the overheating problem is progressively diminished. The maximum stagnation point heating at the highest altitude is reached only when the incident shock misses the cowl lip completely, and any interaction with the cowl bow shock that does occur takes place downstream and thus has little effect on the conditions at the stagnation point.

  18. Biomass shock pretreatment

    SciTech Connect

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  19. Physiopathology of shock

    PubMed Central

    Bonanno, Fabrizio Giuseppe

    2011-01-01

    Shock syndromes are of three types: cardiogenic, hemorrhagic and inflammatory. Hemorrhagic shock has its initial deranged macro-hemodynamic variables in the blood volume and venous return. In cardiogenic shock there is a primary pump failure that has cardiac output/mean arterial pressure as initial deranged variables. In Inflammatory Shock it is the microcirculation that is mainly affected, while the initial deranged macrocirculation variable is the total peripheral resistance hit by systemic inflammatory response. PMID:21769210

  20. Numerical Study of Shock Wave Attenuation Using Logarithmic Spiral Liquid Sheet

    NASA Astrophysics Data System (ADS)

    Wan, Qian; Deiterding, Ralf; Eliasson, Veronica

    2016-11-01

    Research of shock wave attenuation has drawn much attention due to its military and civilian applications. One method to attenuate shock waves is to use water to block the shock wave propagation path and allow the shock wave to lose energy by breaking up the water sheet. We propose a way by holding a water sheet in logarithmic spiral shape, which has the ability of focusing the incident shock wave to its focal region. In addition, the shock wave will break up the bulk water and thus lose energy. The process of shock wave reflecting off and transmitting through the water sheet is numerically modeled using Euler equations and stiffened gas equation of state. In this study, the shock focusing ability of a logarithmic spiral water sheet is compared for various logarithmic spiral sheets. Further, the attenuation effect is quantified by the measurement of pressure impulse and peak pressure behind the transmitted and reflected shock waves.

  1. Shock Refraction at Semi-Rigid Interfaces

    NASA Astrophysics Data System (ADS)

    Miller, Gabrielle; Reynolds, James

    2016-11-01

    We consider a strong spherical air shock encountering a planar interface separating the air from a medium of significantly higher impedance, with the goal of obtaining an approximate analytic description. Before encountering the interface, the incident air shock is well described by the Taylor-Sedov solution for a point blast. The behavior of the reflected and transmitted shocks differs depending upon the height of burst. For moderate heights, despite the relatively small amount of energy transferred, the pressure in the second medium may be much higher than that behind the air shock due to the strong impedance mismatch. Near-surface blasts may be further complicated by the entrainment of material from the second medium and/or the deflection of the interface caused by the strong air shock. For the present study, we ignore the effects of entrainment and assume that the deformation of the interface is small compared to the height of burst. We then investigate the relationship between energy loss into the second medium and the reflected air shock.

  2. Turbulent water coupling in shock wave lithotripsy.

    PubMed

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-02-07

    Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93). If cavitation nuclei remain in the propagation path of successive lithotripter pulses, especially in the acoustic coupling cushion of the shock wave source, they will consume part of the incident wave energy, leading to reduced tensile pressure in the focal region and thus lower stone comminution efficiency. We introduce a method to remove cavitation nuclei from the coupling cushion between successive shock exposures using a jet of degassed water. As a result, pre-focal bubble nuclei lifetime quantified by B-mode ultrasound imaging was reduced from 7 to 0.3 s by a jet with an exit velocity of 62 cm s(-1). Stone fragmentation (percent mass <2 mm) after 250 shocks delivered at 1 Hz was enhanced from 22 ± 6% to 33 ± 5% (p = 0.007) in water without interposing tissue mimicking materials. Stone fragmentation after 500 shocks delivered at 2 Hz was increased from 18 ± 6% to 28 ± 8% (p = 0.04) with an interposing tissue phantom of 8 cm thick. These results demonstrate the critical influence of cavitation bubbles in the coupling cushion on stone comminution and suggest a potential strategy to improve the efficacy of contemporary shock wave lithotripters.

  3. Radiative cooling of shock-heated air in an explosively driven shock tube.

    NASA Technical Reports Server (NTRS)

    Cooper, D. M.; Borucki, W. J.; Chien, K. Y.

    1972-01-01

    Results are presented of an experimental program to measure the effect of radiative cooling on the enthalpy distribution behind incident shock waves traveling in air. The shock velocity was nominally 16 km/sec and the preshock ambient pressure was varied from 0.4 to 1.6 torr. Shock-tube diameters of 4.7 and 9.4 cm were used to investigate the effects of varying optical depths. Radiative cooling rates were determined from spatially resolved measurements of the profile of the H sub alpha line and from absolute measurements of the continuum radiation. The measured enthalpy profiles are in good agreement with the theoretical predictions of Chien and Compton which account for both nongrey and multidimensional aspects of the radiative transport in the shock tube.

  4. Spherical strong-shock generation for shock-ignition inertial fusion

    SciTech Connect

    Theobald, W.; Nora, R.; Seka, W.; Lafon, M.; Anderson, K. S.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Solodov, A. A.; Stoeckl, C.; Edgell, D. H.; Yaakobi, B.; Casner, A.; Reverdin, C.; Ribeyre, X.; Shvydky, A.; Vallet, A.; Peebles, J.; Beg, F. N.; Wei, M. S.; Betti, R.

    2015-05-12

    Recent experiments on the Laboratory for Laser Energetics’ OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of ~2 to 6 x 10¹⁵W/cm² and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser–plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to ~15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength.

  5. Spherical strong-shock generation for shock-ignition inertial fusiona)

    NASA Astrophysics Data System (ADS)

    Theobald, W.; Nora, R.; Seka, W.; Lafon, M.; Anderson, K. S.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Solodov, A. A.; Stoeckl, C.; Edgell, D. H.; Yaakobi, B.; Casner, A.; Reverdin, C.; Ribeyre, X.; Shvydky, A.; Vallet, A.; Peebles, J.; Beg, F. N.; Wei, M. S.; Betti, R.

    2015-05-01

    Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of ˜2 to 6 × 1015 W/cm2 and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser-plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to ˜15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength.

  6. Spherical strong-shock generation for shock-ignition inertial fusion

    SciTech Connect

    Theobald, W.; Seka, W.; Lafon, M.; Anderson, K. S.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Solodov, A. A.; Stoeckl, C.; Edgell, D. H.; Yaakobi, B.; Shvydky, A.; Nora, R.; Betti, R.; Casner, A.; Reverdin, C.; Ribeyre, X.; Vallet, A.; Peebles, J.; Beg, F. N.; and others

    2015-05-15

    Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of ∼2 to 6 × 10{sup 15 }W/cm{sup 2} and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser–plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to ∼15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength.

  7. Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves.

  8. Shock front nonstationarity of supercritical perpendicular shocks

    NASA Astrophysics Data System (ADS)

    Hada, Tohru; Oonishi, Makiko; LembèGe, Bertrand; Savoini, Philippe

    2003-06-01

    The shock front nonstationarity of perpendicular shocks in super-critical regime is analyzed by examining the coupling between "incoming" and "reflected" ion populations. For a given set of parameters including the upstream Mach number (MA) and the fraction α of reflected to incoming ions, a self-consistent, time-stationary solution of the coupling between ion streams and the electromagnetic field is sought for. If such a solution is found, the shock is stationary; otherwise, the shock is nonstationary, leading to a self-reforming shock front often observed in full particle simulations of quasi-perpendicular shocks. A parametric study of this numerical model allows us to define a critical αcrit between stationary and nonstationary regimes. The shock can be nonstationary even for relatively low MA(2-5). For a moderate MA(5-10), the critical value αcrit is about 15 to 20%. For very high MA (>10), αcrit saturates around 20%. Moreover, present full simulations show that self-reformation of the shock front occurs for relatively low βi and disappears for high βi, where βi is the ratio of upstream ion plasma to magnetic field pressures. Results issued from the present theoretical model are found to be in good agreement with full particle simulations for low βi case; this agreement holds as long as the motion of reflected ions is coherent enough (narrow ion ring) to be described by a single population in the model. The present model reveals to be "at variance" with full particle simulations results for the high βi case. Present results are also compared with previous hybrid simulations.

  9. Structure in Radiating Shocks

    NASA Astrophysics Data System (ADS)

    Doss, Forrest

    2010-11-01

    The basic radiative shock experiment is a shock launched into a gas of high-atomic-number material at high velocities, which fulfills the conditions for radiative losses to collapse the post-shock material to over 20 times the initial gas density. This has been accomplished using the OMEGA Laser Facility by illuminating a Be ablator for 1 ns with a total of 4 kJ, launching the requisite shock, faster than 100 km/sec, into a polyimide shock tube filled with Xe. The experiments have lateral dimensions of 600 μm and axial dimensions of 2-3 mm, and are diagnosed by x-ray backlighting. Repeatable structure beyond the one-dimensional picture of a shock as a planar discontinuity was discovered in the experimental data. One form this took was that of radial boundary effects near the tube walls, extended approximately seventy microns into the system. The cause of this effect - low density wall material which is heated by radiation transport ahead of the shock, launching a new converging shock ahead of the main shock - is apparently unique to high-energy-density experiments. Another form of structure is the appearance of small-scale perturbations in the post-shock layer, modulating the shock and material interfaces and creating regions of enhanced and diminished aerial density within the layer. The authors have applied an instability theory, a variation of the Vishniac instability of decelerating shocks, to describe the growth of these perturbations. We have also applied Bayesian statistical methods to better understand the uncertainties associated with measuring shocked layer thickness in the presence of tilt. Collaborators: R. P. Drake, H. F. Robey, C. C. Kuranz, C. M. Huntington, M. J. Grosskopf, D. C. Marion.

  10. Balanced crystalloids for septic shock resuscitation

    PubMed Central

    Corrêa, Thiago Domingos; Cavalcanti, Alexandre Biasi; de Assunção, Murillo Santucci Cesar

    2016-01-01

    Timely fluid administration is crucial to maintain tissue perfusion in septic shock patients. However, the question concerning which fluid should be used for septic shock resuscitation remains a matter of debate. A growing body of evidence suggests that the type, amount and timing of fluid administration during the course of sepsis may affect patient outcomes. Crystalloids have been recommended as the first-line fluids for septic shock resuscitation. Nevertheless, given the inconclusive nature of the available literature, no definitive recommendations about the most appropriate crystalloid solution can be made. Resuscitation of septic and non-septic critically ill patients with unbalanced crystalloids, mainly 0.9% saline, has been associated with a higher incidence of acid-base balance and electrolyte disorders and might be associated with a higher incidence of acute kidney injury. This can result in greater demand for renal replacement therapy and increased mortality. Balanced crystalloids have been proposed as an alternative to unbalanced solutions in order to mitigate their detrimental effects. Nevertheless, the safety and effectiveness of balanced crystalloids for septic shock resuscitation need to be further addressed in a well-designed, multicenter, pragmatic, randomized controlled trial. PMID:28099643

  11. Critical incident reporting systems.

    PubMed

    Ahluwalia, Jag; Marriott, Lin

    2005-02-01

    Approximately 10% of all hospital admissions are complicated by critical incidents in which harm is caused to the patient - this amounts to more than 850,000 incidents annually. Critical incident reporting (CIR) systems refer to the structured reporting, collation and analysis of such incidents. This article describes the attributes required for an effective CIR system. Example neonatal trigger events and a management pathway for handling a critical incident report are described. The benefits and limitations of CIR systems, reactive and prospective approaches to the analysis of actual or potential critical incidents and the assessment of risk are also reviewed. Individual human error is but one contributor in the majority of critical incidents. Recognition of this and the fostering of an organisational culture that views critical incident reports as an opportunity to learn and to improve future patient care is vital if CIR systems are to be effective.

  12. Multiple Shocks, Coping and Welfare Consequences: Natural Disasters and Health Shocks in the Indian Sundarbans

    PubMed Central

    Mazumdar, Sumit; Mazumdar, Papiya Guha; Kanjilal, Barun; Singh, Prashant Kumar

    2014-01-01

    Background Based on a household survey in Indian Sundarbans hit by tropical cyclone Aila in May 2009, this study tests for evidence and argues that health and climatic shocks are essentially linked forming a continuum and with exposure to a marginal one, coping mechanisms and welfare outcomes triggered in the response is significantly affected. Data & Methods The data for this study is based on a cross-sectional household survey carried out during June 2010. The survey was aimed to assess the impact of cyclone Aila on households and consequent coping mechanisms in three of the worst-affected blocks (a sub-district administrative unit), viz. Hingalganj, Gosaba and Patharpratima. The survey covered 809 individuals from 179 households, cross cutting age and gender. A separate module on health-seeking behaviour serves as the information source of health shocks defined as illness episodes (ambulatory or hospitalized) experienced by household members. Key findings Finding reveals that over half of the households (54%) consider that Aila has dealt a high, damaging impact on their household assets. Result further shows deterioration of health status in the period following the incidence of Aila. Finding suggests having suffered multiple shocks increases the number of adverse welfare outcomes by 55%. Whereas, suffering either from the climatic shock (33%) or the health shock (25%) alone increases such risks by a much lesser extent. The multiple-shock households face a significantly higher degree of difficulty to finance expenses arising out of health shocks, as opposed to their counterparts facing only the health shock. Further, these households are more likely to finance the expenses through informal loans and credit from acquaintances or moneylenders. Conclusion This paper presented empirical evidence on how natural and health shocks mutually reinforce their resultant impact, making coping increasingly difficult and present significant risks of welfare loss, having short

  13. Shock absorber control system

    SciTech Connect

    Nakano, Y.; Ohira, M.; Ushida, M.; Miyagawa, T.; Shimodaira, T.

    1987-01-13

    A shock absorber control system is described for controlling a dampening force of a shock absorber of a vehicle comprising: setting means for setting a desired dampening force changeable within a predetermined range; drive means for driving the shock absorber to change the dampening force of the shock absorber linearly; control means for controlling the drive means in accordance with the desired dampening force when the setting of the desired dampening force has been changed; detecting means for detecting an actual dampening force of the shock absorber; and correcting means for correcting the dampening force of the shock absorber by controlling the drive means in accordance with a difference between the desired dampening force and the detected actual dampening force.

  14. Ion dynamics at supercritical quasi-parallel shocks: Hybrid simulations

    NASA Astrophysics Data System (ADS)

    Su, Yanqing; Lu, Quanming; Gao, Xinliang; Huang, Can; Wang, Shui

    2012-09-01

    By separating the incident ions into directly transmitted, downstream thermalized, and diffuse ions, we perform one-dimensional (1D) hybrid simulations to investigate ion dynamics at a supercritical quasi-parallel shock. In the simulations, the angle between the upstream magnetic field and shock nominal direction is θBn=30°, and the Alfven Mach number is MA˜5.5. The shock exhibits a periodic reformation process. The ion reflection occurs at the beginning of the reformation cycle. Part of the reflected ions is trapped between the old and new shock fronts for an extended time period. These particles eventually form superthermal diffuse ions after they escape to the upstream of the new shock front at the end of the reformation cycle. The other reflected ions may return to the shock immediately or be trapped between the old and new shock fronts for a short time period. When the amplitude of the new shock front exceeds that of the old shock front and the reformation cycle is finished, these ions become thermalized ions in the downstream. No noticeable heating can be found in the directly transmitted ions. The relevance of our simulations to the satellite observations is also discussed in the paper.

  15. Incidents of Security Concern

    SciTech Connect

    Atencio, Julian J.

    2014-05-01

    This presentation addresses incidents of security concern and an incident program for addressing them. It addresses the phases of an inquiry, and it divides incidents into categories based on severity and interest types based on whether security, management, or procedural interests are involved. A few scenarios are then analyzed according to these breakdowns.

  16. FULL PARTICLE ELECTROMAGNETIC SIMULATIONS OF ENTROPY GENERATION ACROSS A COLLISIONLESS SHOCK

    SciTech Connect

    Yang, Zhongwei; Liu, Ying D.; Wang, Rui; Hu, Huidong; Parks, George K.; Wu, Pin; Huang, Can; Shi, Run

    2014-09-20

    Experimental data from Cluster have shown that entropy density can be generated across Earth's bow shock. These new observations are a starting point for a more sophisticated analysis that includes computer modeling of a collisionless shock using observed shock parameters as input. In this Letter, we present the first comparison between observations and particle-in-cell simulations of such entropy generation across a collisionless shock. The ion heating at the shock is dominated by the phase mixing of reflected and directly transmitted ions, which are separated from the incident ions. The electron heating is a nearly thermal process due to the conservation of their angular momentum. For both species, we calculate the entropy density across the shock, and obtain good consistency between observations and simulations on entropy generation across the shock. We also find that the entropy generation rate is reduced as the shock Mach number decreases.

  17. Shock initiation of nitromethane

    SciTech Connect

    Yoo, C.S.; Holmes, N.C.

    1993-12-31

    The shock initiation processes of nitromethane have been examined by using a fast time-resolved emission spectroscopy at a two-stage gas gun. a broad, but strong emission has been observed in a spectral range between 350 and 700 nm from shocked nitromethane above 9 GPa. The temporal profile suggests that shocked nitromethane detonates through three characteristic periods, namely an induction period, a hock initiation period, and a thermal explosion period. This paper discusses temporal and chemical characteristics of these periods and present the temperature of the shock-detonating nitromethane at pressures between 9 and 15 GPa.

  18. Anti-Shock Garment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Ames Research Center developed a prototype pressure suit for hemophiliac children, based on research of astronauts' physiological responses in microgravity. Zoex Corporation picked up the design and patents and developed an anti-shock garment for paramedic use. Marketed by Dyna Med, the suit reverses the effect of shock on the body's blood distribution by applying counterpressure to the legs and abdomen, returning blood to vital organs and stabilizing body pressure until the patient reaches a hospital. The DMAST (Dyna Med Anti-Shock Trousers) employ lower pressure than other shock garments, and are non-inflatable.

  19. Effect of Pressure Gradients on the Initiation of PBX-9502 via Irregular (Mach) Reflection of Low Pressure Curved Shock Waves

    SciTech Connect

    Hull, Lawrence Mark; Miller, Phillip Isaac; Moro, Erik Allan

    2016-11-28

    In the instance of multiple fragment impact on cased explosive, isolated curved shocks are generated in the explosive. These curved shocks propagate and may interact and form irregular or Mach reflections along the interaction loci, thereby producing a single shock that may be sufficient to initiate PBX-9501. However, the incident shocks are divergent and their intensity generally decreases as they expand, and the regions behind the Mach stem interaction loci are generally unsupported and allow release waves to rapidly affect the flow. The effects of release waves and divergent shocks may be considered theoretically through a “Shock Change Equation”.

  20. Theory of Mach reflection of detonation at glancing incidence

    DOE PAGES

    Bdzil, John Bohdan; Short, Mark

    2016-12-06

    In this paper, we present a theory for Mach reflection of a detonation undergoing glancing incidence reflection off of a rigid wall. Our focus is on condensed-phase explosives, which we describe with a constant adiabatic gamma equation of state and an irreversible and either state-independent or weakly state-dependent reaction rate. We consider two detonation models: (1) the instantaneous reaction heat-release Chapman–Jouguet (CJ) limit and (2) the spatially resolved reaction heat-release Zeldovich–von Neumann–Dmore » $$\\ddot{Ø}$$ring (ZND) limit, where here we only consider that a small fraction of the detonation energy release is spatially resolved (the SRHR limit). We observe a three-shock reflection in the CJ limit case, with a Mach shock that is curved. In addition, we develop an analytical expression for the triple-point track angle as a function of the angle of incidence. For the SRHR model, we observe a smooth lead shock, akin to von Neumann reflection, with no reflected shock in the reaction zone. Only at larger angles of incidence is a three-shock Mach reflection observed.« less

  1. Theory of Mach reflection of detonation at glancing incidence

    SciTech Connect

    Bdzil, John Bohdan; Short, Mark

    2016-12-06

    In this paper, we present a theory for Mach reflection of a detonation undergoing glancing incidence reflection off of a rigid wall. Our focus is on condensed-phase explosives, which we describe with a constant adiabatic gamma equation of state and an irreversible and either state-independent or weakly state-dependent reaction rate. We consider two detonation models: (1) the instantaneous reaction heat-release Chapman–Jouguet (CJ) limit and (2) the spatially resolved reaction heat-release Zeldovich–von Neumann–D$\\ddot{Ø}$ring (ZND) limit, where here we only consider that a small fraction of the detonation energy release is spatially resolved (the SRHR limit). We observe a three-shock reflection in the CJ limit case, with a Mach shock that is curved. In addition, we develop an analytical expression for the triple-point track angle as a function of the angle of incidence. For the SRHR model, we observe a smooth lead shock, akin to von Neumann reflection, with no reflected shock in the reaction zone. Only at larger angles of incidence is a three-shock Mach reflection observed.

  2. SCATTTERING OF HIGH-ENERGY PARTICLES AT A COLLISIONLESS SHOCK FRONT: DEPENDENCE ON THE SHOCK ANGLE

    SciTech Connect

    Gedalin, M.; Dröge, W.; Kartavykh, Y. Y.

    2015-07-10

    Many shock acceleration theories deal with gyrophase-averaged particle distributions that depend only on the energy and pitch angle of the particles. Diffusive shock acceleration includes shock crossing as a necessary component. As long as the shock width is much smaller than the mean free path of a particle, the crossing is governed by the macroscopic fields inside the transition layer. The dynamics of high-energy particles in these fields is non-adiabatic and gyrophase dependent. The magnetic moment is not conserved in a wide range of shock angles, nor is the condition of reflection determined by the magnetic bottle relation. Instead, for a pitch angle and unknown gyrophase of an incident particle there is a finite probability of reflection. This probability varies between zero and unity in a wide range of pitch angles. In this work we investigate how the matching conditions at the shock front could be modified with the gyrophase dependence taken into account, e.g., in the form of the scattering probabilities.

  3. Blueberry shock virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blueberry shock disease first observed in Washington state in 1987 and initially confused with blueberry scorch caused by Blueberry scorch virus (BlScV). However, shock affected plants produced a second flush of leaves after flowering and the plants appeared normal by late summer except for the lac...

  4. What Is Cardiogenic Shock?

    MedlinePlus

    ... think that you or someone else is in shock, call 9–1–1 right away for emergency treatment. Prompt medical care can save your life and ... half of the people who go into cardiogenic shock survive. This is because of ... improved treatments, such as medicines and devices. These treatments can ...

  5. [Historical vision of shock].

    PubMed

    Dosne Pasqualini, C

    1998-01-01

    The concept of shock and its close relationship with that of stress dates back to the experiments of Hans Selye initiated in 1936 at McGill University in Montreal, with whom I collaborated between 1939 and 1942. It was demonstrated that the General Adaptation Syndrome begins with an Alarm Reaction, which consists of a Stage of Shock and one of Counter-Shock, followed by a Stage of Adaptation and finally a Stage of Exhaustion. My Ph.D. thesis concluded that shock was due to an adrenal insufficiency postulating that active metabolic processes drain the body of certain essential compounds the lack of which causes shock. My interest in the role of the glucose metabolism in shock led me to work with Bernardo Houssay in 1942 at the Institute of Physiology of the University of Buenos Aires and in 1944 with C.N.H. Long at Yale University. There I developed a method for the induction of hemorrhagic shock in the guinea pig with 94% lethality; curiously, the administration of 200 mg of ascorbic acid prevented death. Upon my return to Buenos Aires, these results were confirmed and moreover, it was demonstrated that the administration of cortisone led to 40% survival of the animals while desoxycorticosterone had no effect. At the time, no explanation was available but to-day, half a century later, this Symposium should be able to explain the mechanisms leading to death by hemorrhagic shock.

  6. Normal Shock Vortex Interaction

    DTIC Science & Technology

    2003-03-01

    Figure 9: Breakdown map for normal-shock vortex-interaction. References [1] O. Thomer, W. Schroder and M. Meinke , Numerical Simulation of Normal...and Oblique-Shock Vortex Interaction, ZAMM Band 80, Sub. 1, pp. 181-184, 2000. [2] O. Thomer, E. Krause, W. Schroder and M. Meinke , Computational

  7. Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

    NASA Astrophysics Data System (ADS)

    Mikaelian, Karnig O.

    2016-07-01

    In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and a critical Mach number Mscritical of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mscritical . Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. We point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.

  8. Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

    DOE PAGES

    Mikaelian, Karnig O.

    2016-07-13

    In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and amore » critical Mach number Mcriticals of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mcriticals. Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. Furthermore, we point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.« less

  9. Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

    SciTech Connect

    Mikaelian, Karnig O.

    2016-07-13

    In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and a critical Mach number Mcriticals of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mcriticals. Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. Furthermore, we point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.

  10. Pathophysiology of shock.

    PubMed

    Houston, M C

    1990-06-01

    Shock is an acute widespread reduction in effective tissue perfusion that invokes an imbalance of oxygen supply and demand, anaerobic metabolism, lactic acidosis, cellular and organ dysfunction, metabolic abnormalities, and, if prolonged, irreversible damage and death. The pathophysiologic events in the various types of shock are different and complex with hemodynamic and oxygenation changes, alterations in the composition of the fluid compartments, and various mediators. Shock results from a change in one or a combination of the following: intravascular volume, myocardial function, systemic vascular resistance, or distribution of blood flow. The clinical types of shock include hypovolemic, cardiogenic, distributive (septic), and obstructive. An understanding of the pathophysiologic changes, rapid diagnosis, appropriate monitoring, and appropriate therapy can reduce the high morbidity and mortality in shock states.

  11. Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

    NASA Astrophysics Data System (ADS)

    Groenig, Hans

    Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

  12. Reflection of curved shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

    Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.

  13. Dynamics of concerted bubble cluster collapse in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.; Colonius, Tim; Bailey, Michael R.; Crum, Lawrence A.

    2003-10-01

    Cavitation bubble cluster collapse at the surface of artificial kidney stones during shock wave lithotripsy was investigated in vitro by means of multiframe high-speed photography, passive cavitation detection (PCD), and pressure waveform measurements using a fiber-optic probe hydrophone (FOPH). It was observed that after the passage of the lithotripter shock pulse the stone was covered by numerous individual bubbles. During their growth phase the bubbles coalesced into bubble clusters, with the biggest cluster at the proximal face of the stone. High-speed camera images suggested that cluster collapse started at the periphery and ended with a violent collapse in a small region in the center of the surface of the stone. Shadowgraphy resolved numerous secondary shock waves emitted during this focused collapse. Shock wave emission during cluster collapse was confirmed by PCD. Measurement with the FOPH showed that these shock waves were typically of short duration (0.2 μs). The majority of the shock waves emanating from cluster collapse were low amplitude but some shock waves registered amplitudes on the order of the incident shock pulse (tens of MPa). [Work supported by NIH DK43881, DK55674.

  14. Planar shock wave sliding over a water layer

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Jourdan, G.; Marty, A.; Allou, A.; Parisse, J.-D.

    2016-08-01

    In this work, we conduct experiments to study the interaction between a horizontal free water layer and a planar shock wave that is sliding over it. Experiments are performed at atmospheric pressure in a shock tube with a square cross section (200× 200 mm^2) for depths of 10, 20, and 30 mm; a 1500-mm-long water layer; and two incident planar shock waves having Mach numbers of 1.11 and 1.43. We record the pressure histories and high-speed visualizations to study the flow patterns, surface waves, and spray layers behind the shock wave. We observe two different flow patterns with ripples formed at the air-water interface for the weaker shock wave and the dispersion of a droplet mist for the stronger shock wave. From the pressure signals, we extract the delay time between the arrival of the compression wave into water and the shock wave in air at the same location. We show that the delay time evolves with the distance traveled over the water layer, the depth of the water layer, and the Mach number of the shock wave.

  15. Comparison of shock severity measures

    SciTech Connect

    Baca, T.J.

    1989-01-01

    In an effort to clarify the issues associated with quantifying shock severity, this paper compares the merits of two measures of shock severity. The first measure is the widely used absolute acceleration shock response spectrum (SAA). The second measure of shock severity is relatively new and is known as the shock intensity spectrum (SIS). Overall information content of SAA and SIS spectra are compared and discussed in the context of two shock excitations having known amplitude, duration, and frequency content. The first is a burst of band-limited white noise and the second is a classical haversine pulse. After describing both the SAA and SIS shock measures, numerous examples are described which emphasize the strengths and limitations of each shock characterization method. This discussion reveals how the use of different shock measures may alter an engineer's conclusions about relative shock severity between two shock environments. 8 refs., 15 figs.

  16. Shock Bench Enhancements

    NASA Astrophysics Data System (ADS)

    Charvet, B.; Dilhan, D.; Palladino, M.

    2014-06-01

    In 2008 a contract placed by CNES in partnership with ESA has led MECANO ID to develop a shock bench to qualify spacecraft equipment. A spacecraft shall withstand several shocks without degradation: launcher fairing or stages separation, spacecraft separation, the release of appendage (solar arrays, antenna reflectors, booms) and shocks generated when the pyrovalves of the propulsion system are fired.The Shock Response Spectrum (SRS) requirement, to be applied to the equipment, depends on its mass, its size and its location in the satellite. CNES has performed a survey of the pyroshock qualification requirements on CNES and ESA satellites. The outcome of the activity was the input for the bench development (Fig. 1). The design and sizing of the pyroshock bench started with non linear shock analysis with the help of the Dytran software.A lot of solutions have been compared: mono-plate, bi- plate, Hopkinson bar. The bi-plate was chosen thanks to its very rich frequency content. Also, the shock can be generated on one plate with the equipment mounted on the other, to avoid the direct transmission of the shock to the equipment basis.This study led to a 1000 mm x 650 mm steel bi-plate with a 300 mm aluminum cube fitted on one side. The equipment to test is mounted on the cube (Fig. 2 & 3).

  17. Investigation of shock-shock interaction and Mach reflection in laterally colliding laser-blow-off plasmas

    SciTech Connect

    Kumar, Bhupesh; Singh, R. K.; Sengupta, Sudip; Kaw, P. K.; Kumar, Ajai

    2015-06-15

    Interactions of two Li plasma plumes and shock waves are investigated at various pressures (∼10{sup −5} to 3 mbar) in the argon gas ambient. Fast imaging and optical emission spectroscopy are used to study the plume dynamics and characteristic emission of plasmas. The plasma plumes are created in laser-blow-off geometry. The expansion of plasma plumes in the ambient gas leads to the formation of an interaction zone. The formation of interaction zone is dependent on the ambient pressure and below a certain pressure, no significant change is observed in the shape and size of the interaction plasma. In the higher pressure, formation of interaction zone and its shape are dependent on ambient pressure. Dynamics of seed plasmas and interaction zone are also affected by the shock-shock interactions. The shock-shock interaction depends on the angle of incidence (α) between two shock waves at the initial time of interaction but as the plumes expand, the shock-shock interaction does not follow α dependence.

  18. Echocardiography in shock management.

    PubMed

    McLean, Anthony S

    2016-08-20

    Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.The four core types of shock-cardiogenic, hypovolemic, obstructive, and vasoplegic-can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock.

  19. Shock formation of HCO/+/

    NASA Astrophysics Data System (ADS)

    Elitzur, M.

    1983-04-01

    It is shown that shocks propagating in dense molecular regions will lead to a decrease in HCO(+) relative abundance, in agreement with previous results by Iglesias and Silk (1978). The shock enhancement of HCO(+) detected in the supernova remnant IC 443 by Dickinson et al. (1980) is due to enhanced ionization in the shocked material. This is the result of the material penetrating the remnant cavity where it becomes exposed to the trapped cosmic rays. A similar enhancement appears to have been detected by Wootten in W28 and is explained by the same model.

  20. Sepsis and septic shock.

    PubMed

    Maloney, Patrick J

    2013-08-01

    Early recognition of sepsis and septic shock in children relies on obtaining an attentive clinical history, accurate vital signs, and a physical examination focused on mental status, work of breathing, and circulatory status. Laboratory tests may support the diagnosis but are not reliable in isolation. The goal of septic shock management is reversal of tissue hypoperfusion. The therapeutic end point is shock reversal. Mortality is significantly better among children when managed appropriately. Every physician who cares for children must strive to have a high level of suspicion and keen clinical acumen for recognizing the rare but potentially seriously ill child.

  1. Shock effects in meteorites

    NASA Technical Reports Server (NTRS)

    Stoeffler, D.; Bischoff, A.; Buchwald, V.; Rubin, A. E.

    1988-01-01

    The impacts that can occur between objects on intersecting solar system orbits can generate shock-induced deformations and transformations, creating new mineral phases or melting old ones. These shock-metamorphic effects affect not only the petrography but the chemical and isotopic properties and the ages of primordial meteoritic materials. A fuller understanding of shock metamorphism and breccia formation in meteorites will be essential not only in the study of early accretion, differentiation, and regolith-evolution processes, but in the characterization of the primordial composition of the accreted material itself.

  2. Shocks near Jamming

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; Turner, Ari M.; van Hecke, Martin; Vitelli, Vincenzo

    2012-02-01

    Nonlinear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed and demonstrate that the elementary excitations are strongly nonlinear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.

  3. Incident analysis report

    SciTech Connect

    Gregg, D.W.; Buerer, A.; Leeds, S.

    1996-02-20

    This document presents information about a fire that occurred in January 1996 at Lawrence Livermore National Laboratory. This fire was caused by the spontaneous combustion of 100% fuming nitric acid. Topics discussed include: Summary of the incident; technical background; procedural background; supervision; previous incidents with 100% fuming nitric acid; and judgment of potential hazards.

  4. Ion Dynamics and Field Structure of Quasi-perpendicular Collisionless Shocks near the Critical Mach Number

    NASA Astrophysics Data System (ADS)

    Balikhin, M. A.; Malkov, M.; Sagdeev, R.; Dudnikova, G.

    2015-12-01

    The structure of subcritical (laminar) collisionless shocks has been understood long time ago. When the Mach number exceeds a critical value, some of the incident ions are reflected. This needs to be included into the description of the shock structure and entropy production at the shock front. We present an analytical model of ion reflection from a quasi-perpendicular collisionless shock and the formation of the foot region associated with this reflection. Reflected ions perturb the electrostatic and magnetic fields in the foot region which we self-consistently include in determining the fraction of reflected ions, depending on the Mach number of the shock. The subsequent motion of the shock reflected ions downstream and formation of the downstream field structure is analyzed. Models for thermalization of the downstream plasma and approaches to Rankine-Hugoniot relations will also be discussed. The obtained overall shock structure is compared with the Cluster observations.

  5. Incidence of Menkes disease.

    PubMed

    Tønnesen, T; Kleijer, W J; Horn, N

    1991-02-01

    We have calculated the incidence of Menkes disease for Denmark, France, The Netherlands, the United Kingdom and West Germany, based on known Menkes patients born during the time period 1976-87. Considering live-born Menkes patients, the combined incidence for these five countries is 1 Menkes patient per 298,000 live-born babies. If the number of affected aborted fetuses are taken into account, the incidence is 1 Menkes per 254,000 live-born babies. This incidence, which is 2-4 times lower than earlier published incidence figures, places Menkes disease as an extremely rare disease. The mutation rate for Menkes disease is estimated to be 1.96 x 10(-6), based on the number of isolated Menkes cases born during the time period 1976-87 and the total number of newborn males during this time.

  6. Toxic shock syndrome

    MedlinePlus

    ... by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock-like ... men. Risk factors include: Recent childbirth Infection with Staphylococcus aureus ( S aureus ), commonly called a Staph infection Foreign ...

  7. Early Treatment in Shock

    DTIC Science & Technology

    2011-06-01

    jasminoides Ellis). It is com- monly sold in the United States as an herbal supplement . In terms of crocetin’s fundamental mode of action in host... supplementation 15 can be beneficial in ameliorating the tissue damage produced following experimental 16 hemorrhagic shock. In the present investigation...experimental rat model of hemorrhagic shock. Our studies were designed to test two 19 hypotheses. First, L-arginine supplementation during resuscitation will

  8. Shock Properties of Kimberlite

    NASA Astrophysics Data System (ADS)

    Willmott, G. R.; Proud, W. G.; Field, J. E.

    2004-07-01

    Plate impact experiments have been performed on the igneous diamond-bearing matrix kimberlite. Longitudinal and lateral stresses were measured in the uniaxial strain regime using manganin stress gauges. The shock Hugoniot of the kimberlite has been characterized at axial stresses between 1 and 9 GPa. The kimberlite has a low impedance response when compared with similar data for other geological materials. The data indicate that the rock behaves inelastically above shock stresses of 1 GPa.

  9. Fluid therapy in shock.

    PubMed

    Mandell, D C; King, L G

    1998-05-01

    The goal of treatment for all types of shock is the improvement of tissue perfusion and oxygenation. The mainstay of therapy for hypovolemic and septic shock is the expansion of the intravascular volume by fluid administration, including crystalloids, colloids, and blood products. Frequent physical examinations and monitoring enable the clinician to determine the adequacy of tissue oxygenation and thus the success of the fluid therapy.

  10. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  11. Early Treatment in Shock

    DTIC Science & Technology

    2007-06-01

    1471–2210/2/7. Accessed April 15, 2005. 20. Wang CJ, Lee MJ, Chang MC, Lin JK. Inhibition of tumor promotion in benzo [ a ] pyrene -initiated CD-1 mouse...model. Deliverable: A panel of genes that are reproducibly altered in white blood cells and in liver and muscle by shock and resuscitation. 1. To...Deliverable: Coordinated with objective #1, A panel of genes that are reproducibly altered in white blood cells and in liver and muscle by shock and

  12. Catecholamines in shock.

    PubMed

    Alho, A; Jäättelä, A; Lahdensuu, M; Rokkanen, P; Avikainen, V; Karaharju, E; Tervo, T; Lepistö, P

    1977-06-01

    The role of endogenous catecholamines in various clinical shock and stress states is reviewed; the effects, especially on the peripheral circulation, of catecholamine secretion are the same independent of the cause. Risks of using sympathomimetic agents in the treatment of shock are evaluated. A prolonged noradrenaline activity is to be expected in surgical stress states, e.g. multiple injuries, fat embolism syndrome, burns and infections; therapeutic approaches to minimize the sympathoadrenal activity are outlined.

  13. Electron Acceleration in Shock-Shock Interaction: Simulations and Observations

    NASA Astrophysics Data System (ADS)

    Nakanotani, M.; Matsukiyo, S.; Mazelle, C. X.; Hada, T.

    2015-12-01

    Collisionless shock waves play a crucial role in producing high energy particles (cosmic rays) in space. While most of the past studies about particle acceleration assume the presence of a single shock, in space two shocks frequently come close to or even collide with each other. Hietala et al. [2011] observed the collision of an interplanetary shock and the earth's bow shock and the associated acceleration of energetic ions. The kinetic natures of a shock-shock collision has not been well understood. Only the work done by using hybrid simulation was reported by Cargill et al. [1986], in which they focus on a collision of two supercritical shocks and the resultant ion acceleration. We expect similarly that electron acceleration can also occur in shock-shock collision. To investigate the electron acceleration process in a shock-shock collision, we perform one-dimensional full particle-in-cell (PIC) simulations. In the simulation energetic electrons are observed between the two approaching shocks before colliding. These energetic electrons are efficiently accelerated through multiple reflections at the two shocks (Fermi acceleration). The reflected electrons create a temperature anisotropy and excite large amplitude waves upstream via the electron fire hose instability. The large amplitude waves can scatter the energetic electrons in pitch angle so that some of them gain large pitch angles and are easily reflected when they encounter the shocks subsequently. The reflected electrons can sustain, or probably even strengthen, them. We further discuss observational results of an interaction of interplanetary shocks and the earth's bow shock by examining mainly Cluster data. We focus on whether or not electrons are accelerated in the shock-shock interaction.

  14. AOTV bow shock location

    NASA Technical Reports Server (NTRS)

    Desautel, D.

    1985-01-01

    Hypersonic bow-shock location and geometry are of central importance to the aerodynamics and aerothermodynamics of aeroassisted orbital transfer vehicles (AOTVs), but they are difficult to predict for a given vehicle configuration. This paper reports experimental measurements of shock standoff distance for the 70 deg cone AOTV configuration in shock-tunnel-test flows at Mach numbers of 3.8 to 7.9 and for angles of attack from 0 deg to 20 deg. The controlling parameter for hypersonic bow-shock standoff distance (for a given forebody shape) is the mean normal-shock density ratio. Values for this parameter in the tests reported are in the same range as those of the drag-brake AOTV perigee regime. Results for standoff distance are compared with those previously reported in the literature for this AOTV configuration. It is concluded that the AOTV shock standoff distance for the conical configuration, based on frustrum (base) radius, is equivalent to that of a sphere with a radius about 35 percent greater than that of the cone; the distance is, therefore, much less than reported in previous studies. Some reasons for the discrepancies between the present and previous are advanced. The smaller standoff distance determined here implies there will be less radiative heat transfer than was previously expected.

  15. On the Scaling Law for Broadband Shock Noise Intensity in Supersonic Jets

    NASA Technical Reports Server (NTRS)

    Kanudula, Max

    2009-01-01

    A theoretical model for the scaling of broadband shock noise intensity in supersonic jets was formulated on the basis of linear shock-shear wave interaction. An hypothesis has been postulated that the peak angle of incidence (closer to the critical angle) for the shear wave primarily governs the generation of sound in the interaction process rather than the noise generation contribution from off-peak incident angles. The proposed theory satisfactorily explains the well-known scaling law for the broadband shock -associated noise in supersonic jets.

  16. Partial Spreading of a Laser Beam into a Light Sheet by Shock Waves and Its Use as a Shock Detection Technique

    NASA Technical Reports Server (NTRS)

    Panda, J.

    1994-01-01

    It is observed that when a laser beam is allowed to fall on a shock surface at a grazing incidence, a small part of the beam spreads out in a thin, diverging sheet of light normal to the surface, and both upstream and downstream of the shock. The phenomenon is visualized by observing a cross section of the light sheet on a screen placed normal to the laser path after it touches a shock. The light sheet disappears when the beam is moved to any other locations where there is no shock or the beam pierces the shock surface, i.e., at a non-grazing incidence. The spread angle of the light sheet is considerably higher than the angle by which the beam may bend as it passes through the shock, which produces a small difference of refractive index. Various details indicate that the spread light is a result of diffraction of a small part of the laser beam by the shock whose thickness is nearly the same as that of the laser wavelength. Shocks formed in underexpanded free jets of fully expanded Mach numbers 1.4 to 1.8 are used for this experiment. The above optical phenomenon is used as the basis of a novel shock detection technique which depends on sensing the spread light using a photomultiplier tube (PMT). The locations of the shock surfaces in the underexpanded supersonic jet, obtained using this technique, match with those inferred from the Schlieren photographs and velocity measurements. Moreover, if the shock oscillates, a periodic PMT signal is obtained which provides information about the frequency and amplitude of shock motion.

  17. 2011 Japanese Nuclear Incident

    EPA Pesticide Factsheets

    EPA’s RadNet system monitored the environmental radiation levels in the United States and parts of the Pacific following the Japanese Nuclear Incident. Learn about EPA’s response and view historical laboratory data and news releases.

  18. Shock interaction behind a pair of cylindrical obstacles

    NASA Astrophysics Data System (ADS)

    Liu, Heng; Mazumdar, Raoul; Eliasson, Veronica

    2014-11-01

    The body of work focuses on two-dimensional numerical simulations of shock interaction with a pair of cylindrical obstacles, varying the obstacle separation and incident shock strength. With the shock waves propagating parallel to the center-line between the two cylindrical obstacles, the shock strengths simulated vary from a Mach of 1.4 to a Mach of 2.4, against a wide range of obstacle separation distance to their diameters. These cases are simulated via a software package called Overture, which is used to solve the inviscid Euler equations of gas dynamics on overlapping grids with adaptive mesh refinement. The goal of these cases is to find a so-called ``safe'' region for obstacle spacing and varying shock Mach numbers, such that the pressure in the ``safe'' region is reduced downstream of the obstacles. The benefits apply to both building and armor design for the purpose of shock wave mitigation to keep humans and equipment safe. The results obtained from the simulations confirm that the length of the ``safe'' region and the degree of shock wave attenuation depend on the ratio of obstacle separation distance to obstacle diameter. The influence of various Mach number is also discussed.

  19. 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.

  20. 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

  1. Experimental study of shock-wave reflection from a thermally accommodating wall.

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.

    1973-01-01

    Shock-tube experiments have been conducted to study the nonequilibrium gas-surface interaction which occurs when a thick shock wave in argon reflects from a coplanar, heat-conducting wall. Fast-response instrumentation was used to monitor variations in temperature and normal stress on the surface of the shock-tube end wall during and immediately following reflection of the incident shock wave. The laboratory observations are compared with computer predictions obtained by Deiwert using the direct-simulation Monte Carlo method, and excellent agreement is obtained when a suitable average thermal accommodation coefficient is chosen for the wall surface.

  2. AEROFROSH: a shock condition calculator for multi-component fuel aerosol-laden flows

    DOE PAGES

    Campbell, Matthew Frederick; Haylett, D. R.; Davidson, D. F.; ...

    2015-08-18

    Here, this paper introduces an algorithm that determines the thermodynamic conditions behind incident and reflectedshocksinaerosol-ladenflows.Importantly,the algorithm accounts for the effects of droplet evaporation on post-shock properties. Additionally, this article describes an algorithm for resolving the effects of multiple-component- fuel droplets. This article presents the solution methodology and compares the results to those of another similar shock calculator. It also provides examples to show the impact of droplets on post-shock properties and the impact that multi-component fuel droplets have on shock experimental parameters. Finally, this paper presents a detailed uncertainty analysis of this algorithm’s calculations given typical exper- imental uncertainties

  3. INCIDENCE OF ENDOMETRIAL HYPERPLASIA

    PubMed Central

    REED, Susan D.; NEWTON, Katherine M.; CLINTON, Walter L.; EPPLEIN, Meira; GARCIA, Rochelle; ALLISON, Kimberly; VOIGT, Lynda F.; Weiss, Noel S.

    2009-01-01

    Objective Estimate age-specific incidence of endometrial hyperplasia: simple, complex, and atypical, in order of increasing likelihood of progression to carcinoma. Study design Women ages 18–90 years with endometrial pathology specimens (1985–2003) at a large integrated health plan were identified using automated data. Incidence rates were obtained by dividing the number of cases by the estimated number of female health plan enrollees who retained a uterus. Results Endometrial hyperplasia peak incidence was: simple-142/100,000 woman-years, complex-213/100,000 woman-years, both in the early 50s; and atypical-56/100,000 woman-years in the early 60s. Age-adjusted incidence decreased over the study period, especially for atypical hyperplasia. Conclusions Endometrial hyperplasia incidence without and with atypia peaks in the early postmenopausal years and in the early 60s, respectively. Given that some cases of endometrial hyperplasia likely go undiagnosed, the figures provided should be viewed as minimum estimates of the true incidence. PMID:19393600

  4. Numerical solutions of several reflected shock-wave flow fields with nonequilibrium chemical reactions

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Presley, L. L.; Williams, E. V.

    1972-01-01

    The method of characteristics for a chemically reacting gas is used in the construction of the time-dependent, one-dimensional flow field resulting from the normal reflection of an incident shock wave at the end wall of a shock tube. Nonequilibrium chemical reactions are allowed behind both the incident and reflected shock waves. All the solutions are evaluated for oxygen, but the results are generally representative of any inviscid, nonconducting, and nonradiating diatomic gas. The solutions clearly show that: (1) both the incident- and reflected-shock chemical relaxation times are important in governing the time to attain steady state thermodynamic properties; and (2) adjacent to the end wall, an excess-entropy layer develops wherein the steady state values of all the thermodynamic variables except pressure differ significantly from their corresponding Rankine-Hugoniot equilibrium values.

  5. BIOCHEMICAL STUDIES ON SHOCK

    PubMed Central

    Russell, Jane A.; Long, C. N. H.; Wilhelmi, Alfred E.

    1944-01-01

    1. With increasing severity of shock following hemorrhage in fasted rats there is an increasing depression in the rate of oxygen uptake, in oxygen, of liver slices from the bled animals. The respiration of kidney tissue is only slightly depressed even in severe states of shock. 2. The rates of oxygen uptake of liver tissue from bled rats are nicely correlated with the increases in blood amino nitrogen that follow severe hemorrhage. 3. A supplement of coenzyme factors, in the form of a hot water extract of normal rat liver, increases the oxygen uptake of liver tissue from rats in mild shock, but is without effect on the respiration of liver slices from rats in moderate or severe shock. 4. The ability of rat liver to oxidize succinate is not impaired even in severe shock, but the extra oxygen uptake does not improve the basal rate of respiration of the tissue. 5. Effects on the rate of oxygen uptake of normal rat liver slices comparable to those seen after hemorrhage could be produced by exposing the tissue to an atmosphere of nitrogen for periods of 15 and 60 minutes. This treatment had more marked effects on the respiration of kidney slices than are found after hemorrhage, but the kidney, unlike the liver, exhibited a marked degree of recovery in the presence of glucose. 6. The significance of these findings is briefly discussed. PMID:19871349

  6. Shocks in fragile matter

    NASA Astrophysics Data System (ADS)

    Vitelli, Vincenzo

    2012-02-01

    Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they unjam, these fragile and disordered solids exhibit vanishing elastic moduli and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are continuously compressed, and demonstrate that the resulting excitations are strongly nonlinear shocks, rather than linear waves. We capture the full dependence of the shock speed on pressure and compression speed by a surprisingly simple analytical model. We also treat shear shocks within a simplified viscoelastic model of nearly-isostatic random networks comprised of harmonic springs. In this case, anharmonicity does not originate locally from nonlinear interactions between particles, as in granular media; instead, it emerges from the global architecture of the network. As a result, the diverging width of the shear shocks bears a nonlinear signature of the diverging isostatic length associated with the loss of rigidity in these floppy networks.

  7. Shock Detector for SURF model

    SciTech Connect

    Menikoff, Ralph

    2016-01-11

    SURF and its extension SURFplus are reactive burn models aimed at shock initiation and propagation of detonation waves in high explosives. A distinctive feature of these models is that the burn rate depends on the lead shock pressure. A key part of the models is an algorithm to detect the lead shock. Typically, shock capturing hydro algorithms have small oscillations behind a shock. Here we investigate how well the shock detection algorithm works for a nearly steady propagating detonation wave in one-dimension using the Eulerian xRage code.

  8. Shock-Induced Effect on Chathodoluminesence of Experimentally Shocked Quartz

    NASA Astrophysics Data System (ADS)

    Chang, Y.; Kayama, M.; Tajika, E.; Sekine, Y.; Sekine, T.; Nishido, H.; Kobayashi, T.

    2015-07-01

    We conducted a series of shock recovery experiments on single crystals of natural and synthetic quartz. In the presentation, we show the results of the variation of Cathodoluminescence (CL) spectral features with increasing shock pressure.

  9. Principles and application of shock-tubes and shock tunnels

    NASA Technical Reports Server (NTRS)

    Ried, R. C.; Clauss, H. G., Jr.

    1963-01-01

    The principles, theoretical flow equations, calculation techniques, limitations and practical performance characteristics of basic and high performance shock tubes and shock tunnels are presented. Selected operating curves are included.

  10. Dusty Termination Shocks

    SciTech Connect

    Ip, W.H.

    2004-09-15

    In astrophysical settings, termination shocks where strong stellar wind outflows interact with the surrounding environments tend to take place in dusty regions. Just to name a few, star formation regions, planetary nebulae, supernova remnants and active galactic nuclei are all good examples. Dynamics and evolution of the associated dust clouds could have important influences on the acceleration and composition of energetic particles resulting from the diffusive shock acceleration at the termination shocks. In this note we provide a brief review of previous work predating the recent detection of ACR Mg, Na, Si and S ions which might have originated from the Kuiper belt dust. Their compositional abundance might be diagnostic of the collisional history of the Kupier belt objects.

  11. TIMING OF SHOCK WAVES

    DOEpatents

    Tuck, J.L.

    1955-03-01

    This patent relates to means for ascertaining the instant of arrival of a shock wave in an exploslve charge and apparatus utilizing this means to coordinate the timing of two operations involving a short lnterval of time. A pair of spaced electrodes are inserted along the line of an explosive train with a voltage applied there-across which is insufficient to cause discharge. When it is desired to initiate operation of a device at the time the explosive shock wave reaches a particular point on the explosive line, the device having an inherent time delay, the electrodes are located ahead of the point such that the ionization of the area between the electrodes caused by the traveling explosive shock wave sends a signal to initiate operation of the device to cause it to operate at the proper time. The operated device may be photographic equipment consisting of an x-ray illuminating tube.

  12. Shock absorber servicing tool

    NASA Technical Reports Server (NTRS)

    Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

    1981-01-01

    A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

  13. Anatomy of an incident

    SciTech Connect

    Cournoyer, Michael E.; Trujillo, Stanley; Lawton, Cindy M.; Land, Whitney M.; Schreiber, Stephen B.

    2016-03-23

    A traditional view of incidents is that they are caused by shortcomings in human competence, attention, or attitude. It may be under the label of “loss of situational awareness,” procedure “violation,” or “poor” management. A different view is that human error is not the cause of failure, but a symptom of failure – trouble deeper inside the system. In this perspective, human error is not the conclusion, but rather the starting point of investigations. During an investigation, three types of information are gathered: physical, documentary, and human (recall/experience). Through the causal analysis process, apparent cause or apparent causes are identified as the most probable cause or causes of an incident or condition that management has the control to fix and for which effective recommendations for corrective actions can be generated. A causal analysis identifies relevant human performance factors. In the following presentation, the anatomy of a radiological incident is discussed, and one case study is presented. We analyzed the contributing factors that caused a radiological incident. When underlying conditions, decisions, actions, and inactions that contribute to the incident are identified. This includes weaknesses that may warrant improvements that tolerate error. Measures that reduce consequences or likelihood of recurrence are discussed.

  14. Anatomy of an incident

    DOE PAGES

    Cournoyer, Michael E.; Trujillo, Stanley; Lawton, Cindy M.; ...

    2016-03-23

    A traditional view of incidents is that they are caused by shortcomings in human competence, attention, or attitude. It may be under the label of “loss of situational awareness,” procedure “violation,” or “poor” management. A different view is that human error is not the cause of failure, but a symptom of failure – trouble deeper inside the system. In this perspective, human error is not the conclusion, but rather the starting point of investigations. During an investigation, three types of information are gathered: physical, documentary, and human (recall/experience). Through the causal analysis process, apparent cause or apparent causes are identifiedmore » as the most probable cause or causes of an incident or condition that management has the control to fix and for which effective recommendations for corrective actions can be generated. A causal analysis identifies relevant human performance factors. In the following presentation, the anatomy of a radiological incident is discussed, and one case study is presented. We analyzed the contributing factors that caused a radiological incident. When underlying conditions, decisions, actions, and inactions that contribute to the incident are identified. This includes weaknesses that may warrant improvements that tolerate error. Measures that reduce consequences or likelihood of recurrence are discussed.« less

  15. Culture shock and travelers.

    PubMed

    Stewart, L; Leggat, P A

    1998-06-01

    As travel has become easier and more affordable, the number of people traveling has risen sharply. People travel for many and varied reasons, from the business person on an overseas assignment to backpackers seeking new and exotic destinations. Others may take up residence in different regions, states or countries for family, business or political reasons. Other people are fleeing religious or political persecution. Wherever they go and for whatever reason they go, people take their culture with them. Culture, like language, is acquired innately in early childhood and is then reinforced through formal and complex informal social education into adulthood. Culture provides a framework for interpersonal and social interactions. Therefore, the contact with a new culture is often not the exciting or pleasurable experience anticipated. When immersed in a different culture, people no longer know how to act when faced with disparate value systems. Contact with the unfamiliar culture can lead to anxiety, stress, mental illness and, in extreme cases, physical illness and suicide. "Culture shock" is a term coined by the anthropologist Oberg. It is the shock of the new. It implies that the experience of the new culture is an unpleasant surprise or shock, partly because it is unexpected and partly because it can lead to a negative evaluation of one's own culture. It is also known as cross-cultural adjustment, being that period of anxiety and confusion experienced when entering a new culture. It affects people intellectually, emotionally, behaviorally and physically and is characterized by symptoms of psychological distress. Culture shock affects both adults and children. In travelers or workers who have prolonged sojourns in foreign countries, culture shock may occur not only as they enter the new culture, but also may occur on their return to their original culture. Children may also experience readjustment problems after returning from leading sheltered lives in expatriate

  16. Shock destruction armor system

    DOEpatents

    Froeschner, Kenneth E.

    1993-01-01

    A shock destruction armor system is constructed and arranged to destroy the force of impact of a projectile by shock hydrodynamics. The armor system is designed to comprise a plurality of superimposed armor plates each preferably having a thickness less than five times the projectile's diameter and are preferably separated one-from-another by a distance at least equal to one-half of the projectile's diameter. The armor plates are effective to hydrodynamically and sequentially destroy the projectile. The armor system is particularly adapted for use on various military vehicles, such as tanks, aircraft and ships.

  17. [Corticosteroids and septic shock].

    PubMed

    Bouletreau, P; Petit, P; Latarjet, J

    1976-01-01

    According to the data in the literature, the authors attempted to sum-up present attitudes on the value of corticoids in the treatment of septic shock. If their cardiovascular effects after a period of enthusiasm, are presently rather controversial, their cellular and sub-cellular actions, on the lysosomal membranes, capillary permeability and perhaps the intimate mechanisms of cellular oxygenation seem to be more real. However, the contra-indications which persist in the results of clinical works have resulted in the fact that the exact place of cortico-steroids in the therapeutic arsenal of septic shock still remains to be specified.

  18. Impact-shocked zircons: Discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    NASA Technical Reports Server (NTRS)

    Bohor, B. F.; Betterton, W. J.; Krogh, T. E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows scanning electron microscope (SEM) visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the U-Pb isotopic system.

  19. Radiative reverse shock laser experiments relevant to accretion processes in cataclysmic variables

    SciTech Connect

    Krauland, C. M.; Drake, R. P.; Kuranz, C. C.; Sweeney, R.; Grosskopf, M.; Klein, S.; Gillespie, R.; Keiter, P. A.; Loupias, B.; Falize, E.

    2013-05-15

    We discuss the production of radiative reverse shocks in experiments at the Omega-60 laser facility. The ability of this high-intensity laser to impart large energy densities on micron-thin foils makes it feasible to create supersonic plasma flows. Obtaining a radiative reverse shock in the laboratory requires a sufficiently fast flow (∼100 km/s) of a material whose opacity is large enough to produce energetically significant emission from experimentally achievable shocked layers. The reverse shock forms in the flow once it is impeded. This paper presents the first radiographic data of normal incidence, reverse shockwaves. These experiments are primarily motivated by the contribution of radiative reverse shock waves to the evolving dynamics of the cataclysmic variable (CV) system in which they reside. We show similarity properties to suggest that the experimental production of radiative reserve shocks in the laboratory may be scalable to such astrophysical systems.

  20. Diffraction of a shock wave by a compression corner; regular and single Mach reflection

    NASA Technical Reports Server (NTRS)

    Vijayashankar, V. S.; Kutler, P.; Anderson, D.

    1976-01-01

    The two dimensional, time dependent Euler equations which govern the flow field resulting from the injection of a planar shock with a compression corner are solved with initial conditions that result in either regular reflection or single Mach reflection of the incident planar shock. The Euler equations which are hyperbolic are transformed to include the self similarity of the problem. A normalization procedure is employed to align the reflected shock and the Mach stem as computational boundaries to implement the shock fitting procedure. A special floating fitting scheme is developed in conjunction with the method of characteristics to fit the slip surface. The reflected shock, the Mach stem, and the slip surface are all treated as harp discontinuities, thus, resulting in a more accurate description of the inviscid flow field. The resulting numerical solutions are compared with available experimental data and existing first-order, shock-capturing numerical solutions.

  1. Electron heating and the potential jump across fast mode shocks. [in interplanetary space

    NASA Technical Reports Server (NTRS)

    Schwartz, Steven J.; Thomsen, Michelle F.; Bame, S. J.; Stansberry, John

    1988-01-01

    Two different methods were applied to determine the cross-shock potential jump in the de Hoffmann-Teller reference frame, using a data set that represented 66 crossings of the terrestrial bow shock and 14 interplanetary shocks observed by various ISEE spacecraft, and one crossing each of the Jovian bow shock and the Uranian bow shock made by the Voyager spacecraft. Results for estimates of the electrostatic potential based on an estimate of the jump in electron enthalpy correlated well with estimates based on Liouville's theorem, although the Liouville-determined values were systematically the higher of the two, suggesting that significant irreversible processes contribute to the shape of the downstream distribution. The potential jump corresponds to approximately 12-15 percent of the incident ion ram kinetic energy, and was found not to be controlled by the Mach number, plasma beta, shock geometry, or electron to ion temperature ratios.

  2. Simulation of Interaction of Strong Shocks with Gas Bubbles using the Direct Simulation Monte Carlo Method

    NASA Astrophysics Data System (ADS)

    Puranik, Bhalchandra; Watvisave, Deepak; Bhandarkar, Upendra

    2016-11-01

    The interaction of a shock with a density interface is observed in several technological applications such as supersonic combustion, inertial confinement fusion, and shock-induced fragmentation of kidney and gall-stones. The central physical process in this interaction is the mechanism of the Richtmyer-Meshkov Instability (RMI). The specific situation where the density interface is initially an isolated spherical or cylindrical gas bubble presents a relatively simple geometry that exhibits all the essential RMI processes such as reflected and refracted shocks, secondary instabilities, turbulence and mixing of the species. If the incident shocks are strong, the calorically imperfect nature needs to be modelled. In the present work, we have carried out simulations of the shock-bubble interaction using the DSMC method for such situations. Specifically, an investigation of the shock-bubble interaction with diatomic gases involving rotational and vibrational excitations at high temperatures is performed, and the effects of such high temperature phenomena will be presented.

  3. Flow behind concave shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

    Curved shock theory is introduced and applied to calculate the flow behind concave shock waves. For sonic conditions, three characterizing types of flow are identified, based on the orientation of the sonic line, and it is shown that, depending on the ratio of shock curvatures, a continuously curving shock can exist with Type III flow, where the sonic line intercepts the reflected characteristics from the shock, thus preventing the formation of a reflected shock. The necessary shock curvature ratio for a Type III sonic point does not exist for a hyperbolic shock so that it will revert to Mach reflection for all Mach numbers. A demonstration is provided, by CFD calculations, at Mach 1.2 and 3.

  4. Shock waves data for minerals

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Johnson, Mary L.

    1994-01-01

    Shock compression of the materials of planetary interiors yields data which upon comparison with density-pressure and density-sound velocity profiles constrain internal composition and temperature. Other important applications of shock wave data and related properties are found in the impact mechanics of terrestrial planets and solid satellites. Shock wave equation of state, shock-induced dynamic yielding and phase transitions, and shock temperature are discussed. In regions where a substantial phase change in the material does not occur, the relationship between the particle velocity, U(sub p), and the shock velocity, U(sub s), is given by U(sub s) = C(sub 0) + S U(sub p), where C(sub 0) is the shock velocity at infinitesimally small particle velocity, or the ambient pressure bulk sound velocity. Numerical values for the shock wave equation of state for minerals and related materials of the solar system are provided.

  5. Meteorite incidence angles

    NASA Astrophysics Data System (ADS)

    Hughes, D. W.

    1993-06-01

    Think about an asteroid smashing into the surface of the Moon and excavating a crater; or hitting Earth and scattering meteorite fragments over a strewn field. Imagine a fragment of cometary dust burning out in the Earth's atmosphere and producing a meteor. These bodies have paths that are inclined at some angle to the vertical. But what is the predominant value of this angle of incidence, i? How does the number of incident bodies vary as a function of angle i? And how do both these affect the prevalence of non- circular lunar craters and the ellipticity of meteorite strewn fields?

  6. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  7. Maskelynite: Formation by Explosive Shock.

    PubMed

    Milton, D J; de Carli, P S

    1963-05-10

    When high pressure (250 to 300 kilobars) was applied suddenly (shock-loading) to gabbro, the plagioclase was transformed to a noncrystalline phase (maskelynite) by a solid-state reaction at a low temperature, while the proxene remained crystalline. The shock-loaded gabbro resembles meteorites of the shergottite class; this suggests that the latter formed as a result of shock. The shock-loading of gabbro at 600 to 800 kilobars raised the temperature above the melting range of the plagioclase.

  8. Maskelynite: Formation by explosive shock

    USGS Publications Warehouse

    Milton, D.J.; De Carli, P. S.

    1963-01-01

    When high pressure (250 to 300 kilobars) was applied suddenly (shock-loading) to gabbro, the plagioclase was transformed to a noncrystalline phase (maskelynite) by a solid-state reaction at a low temperature, while the proxene remained crystalline. The shock-loaded gabbro resembles meteorites of the shergottite class; this suggests that the latter formed as a result of shock. The shock-loading of gabbro at 600 to 800 kilobars raised the temperature above the melting range of the plagioclase.

  9. Flow characterization in the NASA Ames 16-inch Shock Tunnel

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Bogdanoff, David W.; Zambrana, Horacio A.; Newfield, Mark E.; Tam, Tim C.

    1992-01-01

    Flow characteristics of NASA's 16-Inch Shock Tunnel are determined for purposes of providing hypersonic propulsion simulation capability. The key tunnel operating parameters are the incident shock speed and reservoir pressure and enthalpy. Flow characteristics of concern are the nozzle exit pressure, temperature, Mach number, Reynolds number, chemical composition, and flow uniformity. Surface mounted gages (for pressure and heat transfer) and nonintrusive optical flow diagnostics (emission and absorption spectroscopy and holographic interferometry) are used to verify tunnel conditions. Experimental measurements are used to validate computational analysis for predicting facility performance, and CFD is used to interpret the free stream optical diagnostic measurements.

  10. Shock tube measurements of specific reaction rates in branched chain CH4-CO-O2 system

    NASA Technical Reports Server (NTRS)

    Brabbs, T. A.; Brokaw, R. S.

    1974-01-01

    Rate constants of two elementary bimolecular reactions involved in the oxidation of methane were determined by monitoring the exponential growth of CO flame band emission behind incident shocks in three suitably chosen gas mixtures.

  11. STEREO interplanetary shocks and foreshocks

    SciTech Connect

    Blanco-Cano, X.; Kajdic, P.; Aguilar-Rodriguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

    2013-06-13

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

  12. Culture Shock and Anthropological Fieldwork.

    ERIC Educational Resources Information Center

    Barker, David Read

    The document reviews literature on the effects of culture shock and suggests reasons that anthropological writings seldom deal with the subject. Definitions of culture shock begin with the writings of anthropologist Kalvero Oberg, who first introduced the term in the mid 1950s. Oberg wrote that culture shock is precipitated by the anxiety that…

  13. The resolved layer of a collisionless, high beta, supercritical, quasi-perpendicular shock wave. II - Dissipative fluid electrodynamics

    NASA Technical Reports Server (NTRS)

    Scudder, J. D.; Aggson, T. L.; Mangeney, A.; Lacombe, C.; Harvey, C. C.

    1986-01-01

    Using the results of Scudder et al. (1986) on the bow shock wave observed by ISEE satellites, a quantitative description is presented of the electrodynamics of ion and electron fluids, and phase-standing wave interaction which manifests itself as a supercritical MHD shock. The cross-shock electrical profile was determined in both the normal incidence frame and in the deHoffman-Teller frame by two different methods, and the results were compared with dc electric field measurements.

  14. Shock compression of nitrobenzene

    NASA Astrophysics Data System (ADS)

    Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu; Fujihisa, Hiroshi; Aoki, Katsutoshi; Yoshida, Masatake; Kondo, Ken-Ichi

    1999-06-01

    The Hugoniot (4 - 30 GPa) and the isotherm (1 - 7 GPa) of nitrobenzene have been investigated by shock and static compression experiments. Nitrobenzene has the most basic structure of nitro aromatic compounds, which are widely used as energetic materials, but nitrobenzene has been considered not to explode in spite of the fact its calculated heat of detonation is similar to TNT, about 1 kcal/g. Explosive plane-wave generators and diamond anvil cell were used for shock and static compression, respectively. The obtained Hugoniot consists of two linear lines, and the kink exists around 10 GPa. The upper line agrees well with the Hugoniot of detonation products calculated by KHT code, so it is expected that nitrobenzene detonates in that area. Nitrobenzene solidifies under 1 GPa of static compression, and the isotherm of solid nitrobenzene was obtained by X-ray diffraction technique. Comparing the Hugoniot and the isotherm, nitrobenzene is in liquid phase under experimented shock condition. From the expected phase diagram, shocked nitrobenzene seems to remain metastable liquid in solid phase region on that diagram.

  15. A Shocking New Pump

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Hydro Dynamics, Inc. received a technical helping hand from NASA that made their Hydrosonic Pump (HPump) a reality. Marshall engineers resolved a bearing problem in the rotor of the pump and recommended new bearings, housings and mounting hardware as a solution. The resulting HPump is able to heat liquids with greater energy efficiency using shock waves to generate heat.

  16. Detonation Shock Radius Experiments.

    NASA Astrophysics Data System (ADS)

    Lambert, David; Debes, Joshua; Stewart, Scott; Yoo, Sunhee

    2007-06-01

    A previous passover experiment [1] was designed to create a complex detonation transient used in validating a reduced, asymptotically derived description of detonation shock dynamics (DSD). An underlying question remained on determining the location of the initial detonation shock radius to start the DSD simulation with respect to the dynamical response of the initiation system coupling's to the main charge. This paper concentrates on determining the initial shock radius required of such DSD governed problems. `Cut-back' experiments of PBX-9501 were conducted using an initiation system that sought to optimize the transferred detonation to the desired constant radius, hemispherical shape. Streak camera techniques captured the breakout on three of the prism's surfaces for time-of-arrival data. The paper includes comparisons to simulations using constant volume explosion and high pressure hot spots. The results of the experiments and simulation efforts provide fundamental design considerations for actual explosive systems and verify necessary conditions from which the asymptotic theory of DSD may apply. [1] Lambert, D., Stewart, D. Scott and Yoo, S. and Wescott, B., ``Experimental Validation of Detonation Shock Dynamics in Condensed Explosives. J. of Fluid Mechs., Vol. 546, pp.227-253 (2006).

  17. Shock Absorbing Helmets

    NASA Technical Reports Server (NTRS)

    1978-01-01

    This paper presents a description of helmets used by football players that offer three times the shock-absorbing capacity of earlier types. An interior padding for the helmets, composed of Temper Foam, first used by NASA's Ames Research Center in the design of aircraft seats is described.

  18. Teleconnected food supply shocks

    NASA Astrophysics Data System (ADS)

    Bren d'Amour, Christopher; Wenz, Leonie; Kalkuhl, Matthias; Steckel, Jan Christoph; Creutzig, Felix

    2016-03-01

    The 2008-2010 food crisis might have been a harbinger of fundamental climate-induced food crises with geopolitical implications. Heat-wave-induced yield losses in Russia and resulting export restrictions led to increases in market prices for wheat across the Middle East, likely contributing to the Arab Spring. With ongoing climate change, temperatures and temperature variability will rise, leading to higher uncertainty in yields for major nutritional crops. Here we investigate which countries are most vulnerable to teleconnected supply-shocks, i.e. where diets strongly rely on the import of wheat, maize, or rice, and where a large share of the population is living in poverty. We find that the Middle East is most sensitive to teleconnected supply shocks in wheat, Central America to supply shocks in maize, and Western Africa to supply shocks in rice. Weighing with poverty levels, Sub-Saharan Africa is most affected. Altogether, a simultaneous 10% reduction in exports of wheat, rice, and maize would reduce caloric intake of 55 million people living in poverty by about 5%. Export bans in major producing regions would put up to 200 million people below the poverty line at risk, 90% of which live in Sub-Saharan Africa. Our results suggest that a region-specific combination of national increases in agricultural productivity and diversification of trade partners and diets can effectively decrease future food security risks.

  19. RAPID INCIDENT RESPONSE FRAMEWORK

    EPA Science Inventory

    Will discuss WERF Contract (RFP# 03-HHE-5PP), Protocols for the Timely Investigation of Potential Health Incidents Associated with Biosolids Land Application, as a member of the project advisory committee. The contractor, University of North Carolina, started work in early June, ...

  20. Diffusive Shock Acceleration

    NASA Astrophysics Data System (ADS)

    Baring, Matthew

    2003-04-01

    The process of diffusive acceleration of charged particles in shocked plasmas is widely invoked in astrophysics to account for the ubiquitous presence of signatures of non-thermal relativistic electrons and ions in the universe. This statistical energization mechanism, manifested in turbulent media, was first posited by Enrico Fermi in 1949 to explain the observed cosmic ray population, which exhibits an almost power-law distribution in rigidity. The absence of a momentum scale is a key characteristic of diffusive shock acceleration, and astrophysical systems generally only impose scales at the injection (low energy) and loss (high energy) ends of the particle spectrum. The existence of structure in the cosmic ray spectrum (the "knee") at around 3000 TeV has promoted contentions that there are at least two origins for cosmic rays, a galactic one supplying those up to the knee, and perhaps an extragalactic one that can explain even the ultra-high energy cosmic rays (UHECRs) seen at 1-300 EeV. Accounting for the UHECRs with familiar astrophysical sites of acceleration has historically proven difficult due to the need to assume high magnetic fields in order to reduce the shortest diffusive acceleration timescale, the ion gyroperiod, to meaningful values. Yet active galaxies and gamma-ray bursts remain strong and interesting candidate sources for UHECRs, turning the theoretical focus to relativistic shocks. This review summarizes properties of diffusive shock acceleration that are salient to the issue of UHECR generation. These include spectral indices, anisotropies, acceleration efficencies and timescales, as functions of the shock speed and mean field orientation, and also the degree of field turbulence. Astrophysical sites for UHECR production are also critiqued.

  1. Reflection of a converging cylindrical shock wave segment by a straight wedge

    NASA Astrophysics Data System (ADS)

    Gray, B.; Skews, B.

    2017-01-01

    As a converging cylindrical shock wave propagates over a wedge, the shock wave accelerates and the angle between the shock wave and the wedge decreases. This causes the conditions at the reflection point to move from what would be the irregular reflection domain for a straight shock wave into the regular reflection domain. This paper covers a largely qualitative study of the reflection of converging shock wave segments with Mach numbers between 1.2 and 2.1 by wedges inclined at angles between 15° and 60° from experimental and numerical results. The sonic condition conventionally used for predicting the type of reflection of straight shock waves was found to also be suitable for predicting the initial reflection of a curved shock wave. Initially regular reflections persisted until the shock was completely reflected by the wedge, whereas the triple point of initially irregular reflections was observed to return to the wedge surface, forming transitioned regular reflection. After the incident shock wave was completely reflected by the wedge, a shock wave focusing mechanism was observed to amplify the pressure on the surface of the wedge by a factor of up to 100 for low wedge angles.

  2. Shock Surface Undulation and Particle Acceleration at Oblique Shocks

    NASA Astrophysics Data System (ADS)

    Krauss-Varban, D.; Li, Y.; Luhmann, J. G.

    2006-12-01

    Considering the average Parker spiral magnetic field configuration, CME-driven interplanetary (IP) shocks within 1 AU should have oblique portions over much of their domain. Indeed, CME-driven shocks observed close to Earth are often oblique. However, it is well known that the standard diffusive shock acceleration mechanism, which relies on self-consistent wave generation via upstream propagating ions and their scattering, becomes increasingly inefficient with greater shock normal angle. Not only is a higher threshold energy required for the ions to leave the shock upstream, but also, approximately-parallel propagating waves are more quickly convected back into the shock, and the growth rate for waves propagating normal to the shock (the ones with the largest convective growth) decreases. As a result, typical, small-scale hybrid simulations of oblique shocks only show a dilute upstream beam, similar to what is often observed at the oblique Earth's bow shock - and no scattered, highly-energized ions. On the other hand, there are many "energetic storm particle" (ESP) events associated with oblique shocks that have significant fluxes of energetic ions. Recently, we have found that when run for a long time, our hybrid simulations (kinetic ions, electron fluid) show that the initial, weak beam is sufficient to generate compressive, steepening upstream waves. These waves are capable of disturbing the shock surface, resulting in an undulation that is propagating along the surface and growing in amplitude over time. The process is akin to that of the well-known reformation occurring at sufficiently strong quasi-parallel shocks. However, here the perturbations require at least two dimensions, show a strong spatial correlation, and travel along the shock surface. This process not only leads to enhanced ion acceleration, but also means that the shock characteristics are difficult to pinpoint, observationally: both the local jumps and the shock normal angle are highly variable

  3. New model for predicting freeway incidents and incident delays

    SciTech Connect

    Sullivan, E.C.

    1997-08-01

    This paper presents a new model that predicts the number of freeway incidents and associated delays based on general freeway segment characteristics, traffic volumes, and incident management procedures. The model is intended to be used in planning capacity-enhancing freeway improvements and incident management programs. Estimates of incident frequencies, severity, durations, and delays are provided for seven standard incident types, each of which represents a significant fraction of total unplanned incidents and has severity and/or duration characteristics substantially different from the others. In addition to describing the incident prediction model, the paper addresses the need for a coordinated national strategy for collecting incident data, with particular attention to urban freeways. It concludes that the incident data systems that have evolved in several urban areas, often in connection with freeway service patrols and incident response team activities, already provide a valuable nationwide data resource for understanding incident patterns and their variations. However, better national coordination of locally collected incident data would be helpful for addressing issues beyond the scope of the local concerns for which virtually all current systems were originally designed. Specific areas for improvement include the definitions of incident types, descriptions of incident locations (relative to both the length and breadth of the highway), and data recording the critical times during incidents such as when detection, response, and clearing occur.

  4. Shock induced dissociation of polyethylene

    SciTech Connect

    Morris, C.E.; Loughran, E.D.; Mortensen, G.F.; Gray, G.T. III; Shaw, M.S.

    1989-01-01

    To identify the physical processes occurring on the Hugoniot, shock-recovery experiments were performed. Cylindrical recovery systems were used that enabled a wide range of single-shock Hugoniot states to be examined. Mass spectroscopy was used to examine the gaseous dissociation products. X-ray and TEM measurements were made to characterize the post-shock carbon structures. A dissociation product equation of state is presented to interpret the observed results. Polyethylene (PE) samples that were multiply shocked to their final states dissociated at much higher pressures than single-shocked samples. 5 refs., 2 figs., 1 tab.

  5. Weak-shock reflection factors

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1993-09-07

    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: square-wave planar shock reflection from wedges; square-wave planar shock reflection from cylinders; and spherical blast wave reflection from a planar surface. We restrict ourselves to weak shocks. Shocks with a Mach number of M{sub O} < 1.56 in air or with an overpressure of {Delta}{sub PI} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  6. Shock detachment from curved wedges

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

    Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.

  7. Table and charts of equilibrium normal shock and shock tube properties for pure argon with velocities to 18 km/sec

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Wilder, S. E.

    1976-01-01

    Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure argon. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 2 to 18 km/sec for a range of initial pressure of 5 N/sq m to 500 kN/sq m. Working charts illustrating shock tube performance with argon test gas and heated helium and hydrogen driver gases are also presented.

  8. Multipoint study of interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Blanco-Cano, Xochitl; Kajdic, Primoz; Russell, Christopher T.; Aguilar-Rodriguez, Ernesto; Jian, Lan K.; Luhmann, Janet G.

    2016-04-01

    Interplanetary (IP) shocks are driven in the heliosphere by Interplanetary Coronal Mass Ejections (ICMEs) and Stream Interaction Regions (SIRs). These shocks perturb the solar wind plasma, and play an active role in the acceleration of ions to suprathermal energies. Shock fronts evolve as they move from the Sun. Their surfaces can be far from uniform and be modulated by changes in the ambient solar wind (magnetic field orientation, flow velocity), shocks rippling, and perturbations upstream and downstream from the shocks, i.e., electromagnetic waves. In this work we use multipoint observations from STEREO, WIND, and MESSENGER missions to study shock characteristics at different helio-longitudes and determine the properties of the waves near them. We also determine shock longitudinal extensions and foreshock sizes. The variations of geometry along the shock surface can result in different extensions of the wave and ion foreshocks ahead of the shocks, and in different wave modes upstream and downtream of the shocks. We find that the ion foreshock can extend up to 0.2 AU ahead of the shock, and that the upstream region with modified solar wind/waves can be very asymmetric.

  9. Pathophysiologic characteristics of hypovolemic shock.

    PubMed

    Moore, K E; Murtaugh, R J

    2001-11-01

    In the late 1800s, while caring for a trauma victim, Warren characterized shock as "a momentary pause in the act of death." A great deal about shock has been discovered since this first description. Dorland's Medical Dictionary defines shock as a condition of profound hemodynamic and metabolic disturbance characterized by failure of the circulatory system to maintain adequate perfusion of vital organs. Shock is now being defined at the cellular level as the inadequate delivery of nutrients to the cells of the body. Because oxygen is the only nutrient that cells cannot store in any appreciable quantity, shock is also equivalent to inadequate oxygen delivery (DO2). Although there are many types of shock, this article concentrates on the pathophysiologic characteristics of hypovolemic shock.

  10. Shock metamorphism of deformed quartz

    NASA Technical Reports Server (NTRS)

    Gratz, Andrew J.; Christie, John; Tyburczy, James; Ahrens, Thomas; Pongratz, Peter

    1988-01-01

    The effect produced by shock loading (to peak pressures of 12 and 24) on deformed synthetic quartz containing a dislocation and abundant bubbles and small inclusions was investigated, and the relationships between preexisting dislocation density shock lamellae in the target material were examined. The resultant material was found to be inhomogeneously deformed and extremely fractured. Results of TEM examinations indicate that no change in dislocation density was caused by shock loading except in regions containing shock lamellae, where the dislocation density was lowered. The shock-induced defects tend to nucleate on and be controlled by preexisting stress concentrators; shock lamellae, glassy veins, and most curviplanar defects form in tension, presumably during release. An extremely mobile silica fluid is formed and injected into fractures during release, which forcibly removes crystalline fragments from vein walls. It is concluded that shock deformation in quartz is dominated by fracture and melting.

  11. Temperature perturbations evolution as a possible mechanism of exothermal reaction kernels formation in shock tubes

    NASA Astrophysics Data System (ADS)

    Drakon, A. V.; Kiverin, A. D.; Yakovenko, I. S.

    2016-11-01

    The basic question raised in the paper concerns the origins of exothermal reaction kernels and the mechanisms of detonation onset behind the reflected shock wave in shock-tube experiments. Using the conventional experimental technique, it is obtained that in the certain diapason of conditions behind the reflected shocks a so-called “mild ignition” arises which is characterized by the detonation formation from the kernel distant from the end-wall. The results of 2-D and 3-D simulations of the flow evolution behind the incident and reflected shocks allow formulation of the following scenario of ignition kernels formation. Initial stage during and after the diaphragm rupture is characterized by a set of non-steady gasdynamical processes. As a result, the flow behind the incident shock occurs to be saturated with temperature perturbations. Further evolution of these perturbations provides generating of the shear stresses in the flow accompanied with intensification of velocity and temperature perturbations. After reflection the shock wave interacts with the formed kernels of higher temperature and more pronounced kernels arise on the background of reactivity profile determined by moving reflected shock. Exothermal reaction starts inside such kernels and propagates into the ambient medium as a spontaneous ignition wave with minimum initial speed equal to the reflected shock wave speed.

  12. Prevalence Incidence Mixture Models

    Cancer.gov

    The R package and webtool fits Prevalence Incidence Mixture models to left-censored and irregularly interval-censored time to event data that is commonly found in screening cohorts assembled from electronic health records. Absolute and relative risk can be estimated for simple random sampling, stratified sampling, and two-phase stratified sampling. Non-parametric (absolute risks only), semi-parametric, weakly-parametric (using B-splines), and some fully parametric (such as the logistic-Weibull) models are supported.

  13. Constipation and Incident CKD.

    PubMed

    Sumida, Keiichi; Molnar, Miklos Z; Potukuchi, Praveen K; Thomas, Fridtjof; Lu, Jun Ling; Matsushita, Kunihiro; Yamagata, Kunihiro; Kalantar-Zadeh, Kamyar; Kovesdy, Csaba P

    2017-04-01

    Constipation is one of the most prevalent conditions in primary care settings and increases the risk of cardiovascular disease, potentially through processes mediated by altered gut microbiota. However, little is known about the association of constipation with CKD. In a nationwide cohort of 3,504,732 United States veterans with an eGFR ≥60 ml/min per 1.73 m(2), we examined the association of constipation status and severity (absent, mild, or moderate/severe), defined using diagnostic codes and laxative use, with incident CKD, incident ESRD, and change in eGFR in Cox models (for time-to-event analyses) and multinomial logistic regression models (for change in eGFR). Among patients, the mean (SD) age was 60.0 (14.1) years old; 93.2% of patients were men, and 24.7% were diabetic. After multivariable adjustments, compared with patients without constipation, patients with constipation had higher incidence rates of CKD (hazard ratio, 1.13; 95% confidence interval [95% CI], 1.11 to 1.14) and ESRD (hazard ratio, 1.09; 95% CI, 1.01 to 1.18) and faster eGFR decline (multinomial odds ratios for eGFR slope <-10, -10 to <-5, and -5 to <-1 versus -1 to <0 ml/min per 1.73 m(2) per year, 1.17; 95% CI, 1.14 to 1.20; 1.07; 95% CI, 1.04 to 1.09; and 1.01; 95% CI, 1.00 to 1.03, respectively). More severe constipation associated with an incrementally higher risk for each renal outcome. In conclusion, constipation status and severity associate with higher risk of incident CKD and ESRD and with progressive eGFR decline, independent of known risk factors. Further studies should elucidate the underlying mechanisms.

  14. SUPERDIFFUSIVE SHOCK ACCELERATION

    SciTech Connect

    Perri, S.; Zimbardo, G.

    2012-05-10

    The theory of diffusive shock acceleration is extended to the case of superdiffusive transport, i.e., when the mean square deviation grows proportionally to t{sup {alpha}}, with {alpha} > 1. Superdiffusion can be described by a statistical process called Levy random walk, in which the propagator is not a Gaussian but it exhibits power-law tails. By using the propagator appropriate for Levy random walk, it is found that the indices of energy spectra of particles are harder than those obtained where a normal diffusion is envisaged, with the spectral index decreasing with the increase of {alpha}. A new scaling for the acceleration time is also found, allowing substantially shorter times than in the case of normal diffusion. Within this framework we can explain a number of observations of flat spectra in various astrophysical and heliospheric contexts, for instance, for the Crab Nebula and the termination shock of the solar wind.

  15. Landing-shock Recorder

    NASA Technical Reports Server (NTRS)

    Brevoort, M J

    1934-01-01

    A description of a special type of seismograph, called a "landing-shock recorder," to be used for measuring the acceleration during impacts such as are experienced in airplane landings, is given . The theory, together with the assumptions made, is discussed in its relation to calculating the acceleration experienced in impact. Calculations are given from records obtained for two impacts of known acceleration. In one case the impact was very severe and in the other it was only moderately severe.

  16. Hydride transport vessel vibration and shock test report

    SciTech Connect

    Tipton, D.G.

    1998-06-01

    Sandia National Laboratories performed vibration and shock testing on a Savannah River Hydride Transport Vessel (HTV) which is used for bulk shipments of tritium. This testing is required to qualify the HTV for transport in the H1616 shipping container. The main requirement for shipment in the H1616 is that the contents (in this case the HTV) have a tritium leak rate of less than 1x10{sup {minus}7} cc/sec after being subjected to shock and vibration normally incident to transport. Helium leak tests performed before and after the vibration and shock testing showed that the HTV remained leaktight under the specified conditions. This report documents the tests performed and the test results.

  17. Clinical review: Hemorrhagic shock

    PubMed Central

    Gutierrez, Guillermo; Reines, H David; Wulf-Gutierrez, Marian E

    2004-01-01

    This review addresses the pathophysiology and treatment of hemorrhagic shock – a condition produced by rapid and significant loss of intravascular volume, which may lead sequentially to hemodynamic instability, decreases in oxygen delivery, decreased tissue perfusion, cellular hypoxia, organ damage, and death. Hemorrhagic shock can be rapidly fatal. The primary goals are to stop the bleeding and to restore circulating blood volume. Resuscitation may well depend on the estimated severity of hemorrhage. It now appears that patients with moderate hypotension from bleeding may benefit by delaying massive fluid resuscitation until they reach a definitive care facility. On the other hand, the use of intravenous fluids, crystalloids or colloids, and blood products can be life saving in those patients who are in severe hemorrhagic shock. The optimal method of resuscitation has not been clearly established. A hemoglobin level of 7–8 g/dl appears to be an appropriate threshold for transfusion in critically ill patients with no evidence of tissue hypoxia. However, maintaining a higher hemoglobin level of 10 g/dl is a reasonable goal in actively bleeding patients, the elderly, or individuals who are at risk for myocardial infarction. Moreover, hemoglobin concentration should not be the only therapeutic guide in actively bleeding patients. Instead, therapy should be aimed at restoring intravascular volume and adequate hemodynamic parameters. PMID:15469601

  18. Radiative effects in radiative shocks in shock tubes

    NASA Astrophysics Data System (ADS)

    Drake, R. P.; Doss, F. W.; McClarren, R. G.; Adams, M. L.; Amato, N.; Bingham, D.; Chou, C. C.; DiStefano, C.; Fidkowski, K.; Fryxell, B.; Gombosi, T. I.; Grosskopf, M. J.; Holloway, J. P.; van der Holst, B.; Huntington, C. M.; Karni, S.; Krauland, C. M.; Kuranz, C. C.; Larsen, E.; van Leer, B.; Mallick, B.; Marion, D.; Martin, W.; Morel, J. E.; Myra, E. S.; Nair, V.; Powell, K. G.; Rauchwerger, L.; Roe, P.; Rutter, E.; Sokolov, I. V.; Stout, Q.; Torralva, B. R.; Toth, G.; Thornton, K.; Visco, A. J.

    2011-09-01

    Using modern high-energy-density facilities it is straightforward to produce radiative shock waves in which the transfer of energy by radiation controls the hydrodynamic structure of the system. Some of these experiments use shock tubes. This paper discusses such experiments, with an emphasis on the simple physical relations that determine the primary features of such shocks and on the details and impact of radiative energy transfer in such systems. Notable aspects include the creation of high-density shocked layers, the flow of radiative energy toward regions of higher energy density, and the creation of secondary shocks by ablation of the tube walls ahead of the primary shock front. Simulations of one such experimental system are also shown.

  19. Reflection and Refraction of Acoustic Waves by a Shock Wave

    NASA Technical Reports Server (NTRS)

    Brillouin, J.

    1957-01-01

    The presence of sound waves in one or the other of the fluid regions on either side of a shock wave is made apparent, in the region under superpressure, by acoustic waves (reflected or refracted according to whether the incident waves lie in the region of superpressure or of subpressure) and by thermal waves. The characteristics of these waves are calculated for a plane, progressive, and uniform incident wave. In the case of refraction, the refracted acoustic wave can, according to the incidence, be plane, progressive, and uniform or take the form of an 'accompanying wave' which remains attached to the front of the shock while sliding parallel to it. In all cases, geometrical constructions permit determination of the kinematic characteristics of the reflected or refractive acoustic waves. The dynamic relationships show that the amplitude of the reflected wave is always less than that of the incident wave. The amplitude of the refracted wave, whatever its type, may in certain cases be greater than that of the incident wave.

  20. Numerical studies of diffusive shock acceleration at spherical shocks

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Jones, T. W.

    2006-05-01

    We have developed a cosmic ray (CR) shock code in one-dimensional spherical geometry with which the particle distribution, the gas flow and their nonlinear interaction can be followed numerically in a frame comoving with an expanding shock. In order to accommodate a very wide dynamic range of diffusion length scales in the CR shock problem, we have incorporated subzone shock tracking and adaptive mesh refinement techniques. We find the spatial grid resolution required for numerical convergence is less stringent in this code compared to typical, fixed-grid Eulerian codes. The improved convergence behavior derives from maintaining the shock discontinuity inside the same grid zone in the comoving code. That feature improves numerical estimates of the compression rate experienced by CRs crossing the subshock compared to codes that allow the subshock to drift on the grid. Using this code with a Bohm-like diffusion model we have calculated the CR acceleration and the nonlinear feedback at supernova remnant shocks during the Sedov-Taylor stage. Similarly to plane-parallel shocks, with an adopted thermal leakage injection model, about 10 -3 of the particles that pass through the shock and up to 60% of the explosion energy are transferred to the CR component. These results are in good agreement with previous nonlinear spherical CR shock calculations of Berezhko and collaborators.

  1. Blast Loading of Epoxy Panels Using a Shock Tube

    NASA Technical Reports Server (NTRS)

    Pankow, Mark; Waas, Anthony M.; Bednarcyk, Brett

    2010-01-01

    The high strain rate mechanical response of thin polymer plates has been studied using a modified shock tube. Diagnostics include the pressure-time history of the incident and reflected pulses and the use of digital image correlation (DIC) techniques to extract the time-history of the out-of-plane displacement distribution. Additionally, finite element models have been developed to understand the plate response and to validate and modify plate material constitutive models that have been proposed.

  2. CMEs as a Shock Structure

    NASA Astrophysics Data System (ADS)

    Muñoz Martínez, Guadalupe; Becerril, Carlos; Lopez-Lopez, Jose Luis

    Interplanetary shocks are associated to approximately one third of the CMEs detected in the interplanetary medium. Even though they have been associated to fast CMEs (V>1000 km/s) it has been shown that some slow ones (V 300 km/s) presented shocks at 1 AU. The structure of the features observed in coronograph images can be hardly compared to the ones detected beyond the coronograph field of view, where the shock is clearly identify. For a few cases, the shock in front of the CME has been distinguish in white light images, but, is there a real visual difference between the CME itself and the considered shock? In this work we compare the optical characteristics of CMEs and some hydrodynamic parameters of ICMEs to show that the feature observed in white light images can be considered as a shock structure.

  3. Shock metamorphism of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Scott, Edward R. D.; Keil, Klaus; Stoeffler, Dieter

    1992-01-01

    Shock effects were studied in 69 carbonaceous chondrites, including CM2, CO3, CV3, ungrouped C2-C4, and CK4-6 chondrites, using optical microscopy of thin sections. It is shown that the classification scheme of Stoeffler et al. (1991) for the progressive stages of shock metamorphism in ordinary chondrites is also applicable to carbonaceous chondrites. On the basis of shock effects in olivine, the 69 carbonaceous chondrites could be assigned to four shock stage, S1 to S4. The CM2 and CO3 groups were found to be the least shocked chondrite groups, whereas the CK4-6 and CV3 were the most strongly shocked groups.

  4. Anaphylactic shock in neuropsychoimmunological research.

    PubMed

    Marković, B M; Dimitrijević, M; Janković, B D

    1992-01-01

    Anaphylaxis appears to be an excellent experimental model for investigating the interactions between central nervous system (CNS) and immune system. Both afferent and efferent regulatory pathways of anaphylactic response are well characterized. The potent mediators of anaphylactic shock, such as histamine and serotonin, are at the same time neurotransmitters, acting in the CNS, and regulators/modulators of the immune system, since receptors for these substances exist on the membrane of the cells of the immune system. In this article the results of studies on the relationship between anaphylaxis and CNS, performed by both pioneers and contemporary investigators, are briefly reviewed. Recent experiments done in our laboratory are presented, which showed that (a) anaphylactic shock can be induced by intracerebroventricular administration of the shocking dose of antigen; (b) rats can learn to associate the induction of anaphylactic shock with neutral stimuli from the environment; and (c) stress in the form of electric tail-shocks reduces the intensity of anaphylactic shock.

  5. Particles Acceleration in Converged Shocks

    NASA Astrophysics Data System (ADS)

    Wang, Xin

    2016-07-01

    Observations show that there is a proton spectral ``break" with E_{break} at 1-10MeV in some large CME-driven shocks. However, the understanding of this energy spectral ``break" from the diffusive shock acceleration theory still remains uncertain. Although previous numerical methods can hardly predict this ``break" from current theoretical models due to high computational expense, the present paper focuses on simulating this energy spectrum in converged two shocks by Monte Carlo numerical method. Considering the Dec 13 2006 CME-driven shock interaction with an Earth bow shock, we examine whether the energy spectral ``break" could occur on an interaction between two shocks. As result, we indeed obtain the maximum proton energy up to 10MeV, and we further find a proton spectral ``break" appears distinctly at the energy ˜5MeV.

  6. An experimental study of shock wave propagation through a polyester film

    NASA Astrophysics Data System (ADS)

    Eliasson, Veronica; Jeon, Hongjoo

    2016-11-01

    A polyester film is available in a variety of uses such as packaging, protective overlay, barrier protection, and other industrial applications. In the current study, shock tube experiments are performed to study the influence of a polyester film on the propagation of a planar shock wave. A conventional shock tube is used to create incident shock Mach numbers of Ms = 1.34 and 1.46. A test section of the shock tube is designed to hold a 0.009 mm, 0.127 mm, 0.254 mm, or 0.508 mm thick polyester film (Dura-Lar). High-temporal resolution schlieren photography is used to visualize the shock wave mitigation caused by the polyester film. In addition, four pressure transducers are used to measure the elapsed time of arrival and overpressure of the shock wave both upstream and downstream of the test section. Results show that the transmitted shock wave in the polyester film is clearly observed and the transmitted shock Mach number is decreased by increasing film thickness. This study is supported by the National Science Foundation under Grant No. CBET-1437412.

  7. Physics of collisionless shocks: theory and simulation

    NASA Astrophysics Data System (ADS)

    Stockem Novo, A.; Bret, A.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    Collisionless shocks occur in various fields of physics. In the context of space and astrophysics they have been investigated for many decades. However, a thorough understanding of shock formation and particle acceleration is still missing. Collisionless shocks can be distinguished into electromagnetic and electrostatic shocks. Electromagnetic shocks are of importance mainly in astrophysical environments and they are mediated by the Weibel or filamentation instability. In such shocks, charged particles gain energy by diffusive shock acceleration. Electrostatic shocks are characterized by a strong electrostatic field, which leads to electron trapping. Ions are accelerated by reflection from the electrostatic potential. Shock formation and particle acceleration will be discussed in theory and simulations.

  8. Flexible Multi-Shock Shield

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L. (Inventor); Crews, Jeanne L. (Inventor)

    2005-01-01

    Flexible multi-shock shield system and method are disclosed for defending against hypervelocity particles. The flexible multi-shock shield system and method may include a number of flexible bumpers or shield layers spaced apart by one or more resilient support layers, all of which may be encapsulated in a protective cover. Fasteners associated with the protective cover allow the flexible multi-shock shield to be secured to the surface of a structure to be protected.

  9. Diffraction of a shock into an expansion wavefront for the transonic self-similar nonlinear wave system in two space dimensions

    NASA Astrophysics Data System (ADS)

    Jang, Juhi; Kim, Eun Heui

    2016-01-01

    We consider a configuration where a planar shock reflects and diffracts as it hits a semi-infinite rigid screen. The diffracted reflected shock meets the diffracted expansion wave, created by the incident shock that does not hit the screen, and changes continuously from a shock into an expansion. The governing equation changes its type and becomes degenerate as the wave changes continuously from a shock to an expansion. Furthermore the governing equation has multiple free boundaries (transonic shocks) and an additional degenerate sonic boundary (the expansion wave). We develop an analysis to understand the solution structure near which the shock strength approaches zero and the shock turns continuously into an expansion wavefront, and show the existence of the global solution to this configuration for the nonlinear wave system. Moreover we provide an asymptotic analysis to estimate the position of the change of the wave, and present intriguing numerical results.

  10. Common Causes of Pesticide Incidents

    EPA Pesticide Factsheets

    There are many types of pesticide incidents. EPA staff analyze pesticide incident reports involving people (including children and farm workers), pets, domestic animals, wildlife including bees and other pollinators, and the environment.

  11. Experimental and computational study of the effect of shocks on film cooling effectiveness in scramjet combustors

    NASA Technical Reports Server (NTRS)

    Kamath, Pradeep S.; Holden, Michael S.; Mcclinton, Charles R.

    1990-01-01

    This paper presents results from a study conducted to investigate the effect of incident oblique shocks on the effectiveness of a coolant film at Mach numbers, typical of those expected in a scramjet combustor at Mach 15 to 20 flight. Computations with a parabolic code are in good agreement with the measured pressures and heat fluxes, after accounting for the influence of the shock upstream of its point of impingement on the plate, and the expansion from the trailing edge of the shock generator. The test data shows that, for the blowing rates tested, the film is rendered largely ineffective by the shock. Computations show that coolant blowing rates five to ten times those tested are required to protect against shock-induced heating. The implications of the results to scramjet combustor design are discussed.

  12. Formation of triple shock configurations with negative reflection angle in steady flows

    NASA Astrophysics Data System (ADS)

    Gvozdeva, L. G.; Gavrenkov, S. A.

    2012-04-01

    Triple configurations of shock waves with negative reflection angles are considered. These configurations have been observed in quasi-steady cases of shock wave reflection from a planar wedge in real gases, while in steady cases three-shock configurations are only known to occur with positive reflection angles. Boundaries for the appearance of a three-shock configuration with a negative reflection angle in steady cases are analytically determined as dependent on the initial Mach number of the flow, angle of incidence, and adiabatic index. The formation of a three-shock configuration with a negative reflection angle in a steady flow must lead to a change in the character of the wave pattern, and under certain conditions it can lead to instability.

  13. A study of the weak shock wave propagating over a porous wall/cavity system

    NASA Astrophysics Data System (ADS)

    Kim, H. D.; Jung, S. J.; Aoki, T.; Setoguchi, T.

    2005-12-01

    The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity system is investigated with computational fluid dynamics. A total variation diminishing scheme is employed to solve the unsteady, two-dimensional, compressible, Navier-Stokes equations. The Mach number of an initial shock wave is changed in the range from 1.02 to 1.12. Several different types of porous wall/cavity systems are tested to investigate the passive control effects. The results show that wall pressure strongly fluctuates due to diffraction and reflection processes of the shock waves behind the incident shock wave. From the results, it is understood that for effective alleviation of tunnel impulse waves, the length of the perforated region should be sufficiently long.

  14. Martian bow shock - Phobos observations

    NASA Technical Reports Server (NTRS)

    Schwingenschuh, K.; Riedler, W.; Lichtenegger, H.; Eroshenko, E.; Sauer, K.

    1990-01-01

    Data obtained with the Magma magnetometer on the subsolar passes of the Phobos spacecraft during its 3 elliptic orbits reveals a turbulent bow shock with a strong foot consistent with the reflection of solar wind protons. The bow shock lies at a subsolar distance of 1.47 + or - .03 R(M). The circular orbit phase of the mission reveals a bow shock with a highly varying location. The median terminator crossing lies at 2.72 Mars radii. The location of the bow shock in the terminator plane is sensitive to neither the EUV flux nor to planetary longitude.

  15. Martian bow shock: Phobos observations

    SciTech Connect

    Schwingenschuh, K.; Riedler, W.; Lichtenegger, H. ); Yeroshenko, Ye. ); Sauer, K. ); Luhmann, J.G.; Ong, M.; Russell, C.T. )

    1990-05-01

    Data obtained with the MAGMA magnetometer on the subsolar passes of the Phobos spacecraft during its 3 elliptic orbits reveals a turbulent bow shock with a strong foot consistent with the reflection of solar wind protons. The bow shock lies at a subsolar distance of 1.47 {plus minus} .03 R{sub M}. The circular orbit phase of the mission reveals a bow shock with a highly varying location. The median terminator crossing lies at 2.72 Mars radii. The location of the bow shock in the terminator plane is sensitive to neither the EUV flux nor to planetary longitude.

  16. Shock metamorphism of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Stoeffler, Dieter; Keil, Klaus; Scott, Edward R. D.

    1991-01-01

    This study proposes a revised petrographic classification of progressive stages of shock metamorphism of 26 ordinary chondrites. Six stages of shock (S1 to S6) are defined on the basis of shock effects in olivine and plagioclase as recognized by thin section microscopy, and the characteristic shock effects of each shock stage are described. It is concluded that shock effects and the sequence of progressively increasing degrees of shock metamorphosis are very similar in H, L, and LL groups. Differences in the frequency distribution of shock stages are relatively minor. It is suggested that the collisional histories of the H, L, and LL parent bodies were similar. Petrologic type-3 chondrites are deficient in stages S4 and S6 and, with increasing petrologic type, the frequency of stages S4 to S6 increases. It is suggested that the more porous and volatile-rich Type-3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type. Stage S3 is the most abundant in nearly all petrologic types.

  17. Shock metamorphism in lunar samples.

    PubMed

    von Engelhardt, W; Arndt, J; Müller, W F; Stöffler, D

    1970-01-30

    Indications of shock metamorphism produced by pressures up to the megabar region have been observed in the fine material and the breccias, but very rarely in the coarser fragments of crystalline rocks. These indications are deformation structures in plagioclase and pyroxene, diaplectic plagioclase glasses, and glasses formed by shock-induced melting of lunar rocks. Two sources of shock waves have been distinguished: primary impact of meteorites and secondary impact of crater ejecta. There are two major chemical types of shock-induced melts. The differences in chemistry may be related to impact sites in mare and highland areas.

  18. Quasiperpendicular High Mach Number Shocks

    NASA Astrophysics Data System (ADS)

    Sulaiman, A. H.; Masters, A.; Dougherty, M. K.; Burgess, D.; Fujimoto, M.; Hospodarsky, G. B.

    2015-09-01

    Shock waves exist throughout the Universe and are fundamental to understanding the nature of collisionless plasmas. Reformation is a process, driven by microphysics, which typically occurs at high Mach number supercritical shocks. While ongoing studies have investigated this process extensively both theoretically and via simulations, their observations remain few and far between. In this Letter we present a study of very high Mach number shocks in a parameter space that has been poorly explored and we identify reformation using in situ magnetic field observations from the Cassini spacecraft at 10 AU. This has given us an insight into quasiperpendicular shocks across 2 orders of magnitude in Alfvén Mach number (MA ) which could potentially bridge the gap between modest terrestrial shocks and more exotic astrophysical shocks. For the first time, we show evidence for cyclic reformation controlled by specular ion reflection occurring at the predicted time scale of ˜0.3 τc , where τc is the ion gyroperiod. In addition, we experimentally reveal the relationship between reformation and MA and focus on the magnetic structure of such shocks to further show that for the same MA , a reforming shock exhibits stronger magnetic field amplification than a shock that is not reforming.

  19. Martian bow shock - PHOBOS observations

    NASA Astrophysics Data System (ADS)

    Schwingenschuh, K.; Riedler, W.; Lichtenegger, H.; Yeroshenko, Ye.; Sauer, K.; Luhmann, J. G.; Ong, M.; Russell, C. T.

    1990-05-01

    Data obtained with the Magma magnetometer on the subsolar passes of the Phobos spacecraft during its 3 elliptic orbits reveals a turbulent bow shock with a strong foot consistent with the reflection of solar wind protons. The bow shock lies at a subsolar distance of 1.47 + or - .03 R(M). The circular orbit phase of the mission reveals a bow shock with a highly varying location. The median terminator crossing lies at 2.72 Mars radii. The location of the bow shock in the terminator plane is sensitive to neither the EUV flux nor to planetary longitude.

  20. Endocrinology of shock.

    PubMed

    Woolf, P D

    1986-12-01

    The development of shock initiates a cascade of responses in an effort to reestablish homeostasis. Three of the most important hormonal and neurohumoral changes are the secretion of glucocorticoids, catecholamines, and vasopressin. Regulation of adrenal function is much more complex than originally thought. Hemorrhage is a potent stimulus for cortisol release, and both ACTH and ACTH-independent mechanisms have been described. The ACTH response to its releasing hormone, corticotropin releasing hormone (CRF), is itself amplified by vasopressin, which appears to have intrinsic CRF properties. Because ACTH is synthesized as part of a large precursor molecule (pro-opiomelanocortin) containing the amino acid sequences for several important proteins, stimulation of ACTH release has far-ranging effects, the specifics of which are just being clarified. Norepinephrine and epinephrine levels increase manyfold above baseline within minutes of the onset of hemorrhagic shock. Only patients experiencing cardiac arrest or the rare patient with a very active pheochromocytoma have higher concentrations. The levels reached are far in excess of those required to cause both cardiovascular and metabolic alterations. Because of the presence of the endogenous opiates leucine and methionine enkephalin in the neurosecretory granule, it is very likely that the enkephalins are coreleased with the catecholamines, modifying their cardiovascular effects and producing analgesia. Hypovolemia is also a potent stimulus for vasopressin secretion, which overrides hypotonicity, presenting a clinical picture quite compatible with the syndrome of inappropriate antidiuretic hormone secretion, from which it must be differentiated. Vasopressin also is released by pain, nausea, and hypoxia, all of which are likely to be present in the patient with shock.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Nonlinear Interaction of a Shock Wave with an Anisotropic Entropy Perturbation Field

    NASA Astrophysics Data System (ADS)

    Gorodnichev, K. E.; Kuratov, S. E.; Gorodnichev, E. E.

    2017-01-01

    The problem of the interaction of a shock wave with an anisotropic entropy perturbation field has been solved including second-order corrections to hydrodynamic quantities. It has been shown that nonlinear interactions between acoustic waves result in the localization of acoustic perturbations behind the shock front. This effect is observed when sound attenuation is absent in the linear approximation. The problem of the propagation of the shock wave in an incident sample, where the spatially anisotropic density perturbation field initially exists, has been numerically solved in application to the collision of two plates. Numerical calculations confirm the results of the theoretical analysis.

  2. Characterization of mechanical shock waves in aluminum 6061-T6 using a high power laser pulse

    NASA Astrophysics Data System (ADS)

    Gonzalez Romero, J. R.; García-Torales, G.; Gómez Rosas, G.; Ocaña, J. L.; Flores, Jorge L.

    2016-09-01

    Strengthening techniques allows enhance metal physical properties. Laser shock peening (LSP) technique consist in a surface treatment which a high power laser pulse induces a compressive residual stress field through mechanical shock waves, increasing hardness, corrosion resistance, fatigue resistance. In comparison with the shot peening technique, LSP is a method that allows precision controlling the laser incidence on the surface under treatment increasing the surface quality in the surface under treatment. In this work, mechanical shock waves are induced in aluminum and measure using two different experimental approaches. First, using a PVDZ sensors and secondly, strain gauges are used. Experimental results are presented.

  3. Control of shock-wave boundary-layer interactions by bleed in supersonic mixed compression inlets

    NASA Technical Reports Server (NTRS)

    Fukuda, M. K.; Reshotko, E.; Hingst, W. R.

    1975-01-01

    An experimental investigation has been conducted to determine the effect of bleed region geometry and bleed rate on shock wave-boundary layer interactions in an axisymmetric, mixed-compression inlet at a Mach number of 2.5. The full realizable reduction in transformed form factor is obtained by bleeding off about half the incident boundary layer mass flow. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise. Slanted holes are more effective than normal holes. Two different bleed hole sizes were tested without detectable difference in performance.

  4. Incident Management: Process into Practice

    ERIC Educational Resources Information Center

    Isaac, Gayle; Moore, Brian

    2011-01-01

    Tornados, shootings, fires--these are emergencies that require fast action by school district personnel, but they are not the only incidents that require risk management. The authors have introduced the National Incident Management System (NIMS) and the Incident Command System (ICS) and assured that these systems can help educators plan for and…

  5. Shock Absorbing System

    NASA Astrophysics Data System (ADS)

    1982-01-01

    A lightweight, inexpensive shock-absorbing system, developed by Langley Research Center 20 years ago, is now in service as safety device for an automated railway at Duke University Medical Center. The transportation system travels at about 25 miles per hour, carrying patients, visitors, staff and cargo. At the end of each guideway of the system are "frangible," (breakable) tube "buffers." If a slowing car fails to make a complete stop at the terminal, it would bump and shatter the tubes, absorbing energy that might otherwise jolt the passengers or damage the vehicle.

  6. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  7. Characterization of Shocked Beryllium

    SciTech Connect

    Cady, Carl M; Adams, Chris D; Hull, Lawrence M; Gray III, George T; Prime, Michael B; Addessio, Francis L; Wynn, Thomas A; Brown, Eric N

    2012-08-24

    Beryllium metal has many excellent structural properties in addition to its unique radiation characteristics, including: high elastic modulus, low Poisson's ratio, low density, and high melting point. However, it suffers from several major mechanical drawbacks: 1) high anisotropy - due to its hexagonal lattice structure and its susceptibility to crystallographic texturing; 2) susceptibility to impurity-induced fracture - due to grain boundary segregation; and 3) low intrinsic ductility at ambient temperatures thereby limiting fabricability. While large ductility results from deformation under the conditions of compression, the material can exhibit a brittle behavior under tension. Furthermore, there is a brittle to ductile transition at approximately 200 C under tensile conditions. While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. The beryllium used in this study was Grade S200-F (Brush Wellman, Inc., Elmore, OH) material. The work focused on high strain rate deformation and examine the validity of constitutive models in deformation rate regimes, including shock, the experiments were modeled using a Lagrangian hydrocode. Two constitutive strength (plasticity) models, the Preston-Tonks-Wallace (PTW) and Mechanical Threshold Stress (MTS) models, were calibrated using the same set of quasi-static and Hopkinson bar data taken at temperatures from 77K to 873K and strain rates from 0.001/sec to 4300/sec. In spite of being calibrated on the same data, the two models give noticeably different results when compared with the measured wave profiles. These high strain rate tests were conducted using both explosive drive and a gas gun to

  8. Hypovolemic shock resuscitation.

    PubMed

    Kobayashi, Leslie; Costantini, Todd W; Coimbra, Raul

    2012-12-01

    Several changes in the way patients with hemorrhagic shock are resuscitated have occurred over the past decades, including permissive hypotension, minimal crystalloid resuscitation, earlier blood transfusion, and higher plasma and platelet-to-red cell ratios. Hemostatic adjuncts, such as tranexamic acid and prothrombin complex, and the use of new methods of assessing coagulopathy are also being incorporated into resuscitation of the bleeding patient. These ideas have been incorporated by many trauma centers into institutional massive transfusion protocols, and adoption of these protocols has resulted in improvements in mortality and morbidity. This article discusses each of these new resuscitation strategies and the evidence supporting their use.

  9. Management of septic shock.

    PubMed Central

    Edwards, J D

    1993-01-01

    There have been important advances in the resuscitation of patients in septic shock in recent years. Survival can be improved by earlier recognition and therefore eradication of the sepsis combined with logical supportive measures. As with any acutely ill patient consultation with intensive care unit staff may be useful. Consultation with the intensive care unit does not necessarily imply the need for admission and mechanical ventilation; helpful advice may be forthcoming. Equally, referral to the intensive care unit does not mean an admission of failure but merely a recognition that additional skills and technical facilities are necessary for the patient's survival. PMID:8324438

  10. Toxic shock syndrome.

    PubMed Central

    Todd, J K

    1988-01-01

    In the past 10 years, we have learned much about TSS and S. aureus and its toxins. A number of important biologic principles have been reemphasized in this first decade of TSS research: S. aureus is a very complex organism, one not likely to yield quick answers; in vitro observations must always be confirmed in the patient; animal models may not always be reliable replicates of human disease; and epidemiologic associations cannot be equated with causation. Toxic shock is an intricate phenomenon with many interesting scientific facets. Unraveling its mysteries will undoubtedly teach us more about the complex interaction of patients and microorganisms. PMID:3069202

  11. Richtmyer-Meshkov instability of a flat interface subjected to a rippled shock wave

    NASA Astrophysics Data System (ADS)

    Zou, Liyong; Liu, Jinhong; Liao, Shenfei; Zheng, Xianxu; Zhai, Zhigang; Luo, Xisheng

    2017-01-01

    The Richtmyer-Meshkov (RM) instability of a nominally flat interface (N2/SF6 ) subjected to a rippled shock, as the counterpart of a corrugated interface interacting with a planar shock, is studied experimentally in a vertical shock tube using both schlieren photography and fog visualization diagnostics. The nonplanar incident shock wave is produced by a planar shock diffracting around a rigid cylinder, and the flat interface is created by a membraneless technique. Three different distances η (the ratio of spacing from cylinder to interface over cylinder diameter) are considered. Schlieren images indicate that the nonplanar incident shock can be divided into three different segments separated by two triple points. Fog visualization pictures show the formation of overall "Λ " shaped interface structures and a N2 cavity at the center and two interface steps at both sides. With the increase of the dimensionless time, the dimensionless interface amplitude increases as well as the penetration depth of the cavity, and both curves exhibit reasonable collapse for different η numbers. Through equating the preinterface perturbation of the rippled shock with a preshock perturbation of a corrugated interface, the growth rate of this instability is found to be noticeably smaller than that of the standard RM instability.

  12. Experimental and numerical study of shock-driven collapse of multiple cavity arrays

    NASA Astrophysics Data System (ADS)

    Betney, Matthew; Anderson, Phillip; Tully, Brett; Doyle, Hugo; Hawker, Nicholas; Ventikos, Yiannis

    2014-10-01

    This study presents a numerical and experimental investigation of the interaction of a single shock wave with multiple air-filled spherical cavities. The 5 mm diameter cavities are cast in a hydrogel, and collapsed by a shock wave generated by the impact of a projectile fired from a single-stage light-gas gun. Incident shock pressures of up to 1 GPa have been measured, and the results compared to simulations conducted using a front-tracking approach. The authors have previously studied the collapse dynamics of a single cavity. An important process is the formation of a high-speed transverse jet, which impacts the leeward cavity wall and produces a shockwave. The speed of this shock has been measured using schlieren imaging, and the density has been measured with a fibre optic probe. This confirmed the computational prediction that the produced shock is of a higher pressure than the original incident shock. When employing multiple cavity arrays, the strong shock produced by the collapse of one cavity can substantially affect the collapse of further cavities. With control over cavity placement, these effects may be utilised to intensify collapse. This intensification is experimentally measured via analysis of the optical emission.

  13. Richtmyer-Meshkov instability of a flat interface subjected to a rippled shock wave.

    PubMed

    Zou, Liyong; Liu, Jinhong; Liao, Shenfei; Zheng, Xianxu; Zhai, Zhigang; Luo, Xisheng

    2017-01-01

    The Richtmyer-Meshkov (RM) instability of a nominally flat interface (N_{2}/SF_{6}) subjected to a rippled shock, as the counterpart of a corrugated interface interacting with a planar shock, is studied experimentally in a vertical shock tube using both schlieren photography and fog visualization diagnostics. The nonplanar incident shock wave is produced by a planar shock diffracting around a rigid cylinder, and the flat interface is created by a membraneless technique. Three different distances η (the ratio of spacing from cylinder to interface over cylinder diameter) are considered. Schlieren images indicate that the nonplanar incident shock can be divided into three different segments separated by two triple points. Fog visualization pictures show the formation of overall "Λ" shaped interface structures and a N_{2} cavity at the center and two interface steps at both sides. With the increase of the dimensionless time, the dimensionless interface amplitude increases as well as the penetration depth of the cavity, and both curves exhibit reasonable collapse for different η numbers. Through equating the preinterface perturbation of the rippled shock with a preshock perturbation of a corrugated interface, the growth rate of this instability is found to be noticeably smaller than that of the standard RM instability.

  14. Hot-Electron and Strong-Shock Generation at Shock-Ignition-Relevant Laser Intensities

    NASA Astrophysics Data System (ADS)

    Theobald, W.; Betti, R.; Nora, R.; Seka, W.; Lafon, M.; Michel, D. T.; Stoeckl, C.; Casner, A.; Peebles, J.; Beg, F. N.; Ribeyre, X.; Vallet, A.; Wei, M. S.

    2015-11-01

    The effect of hot electrons on the formation of spherical shocks in solid targets was studied in direct-illumination experiments on OMEGA at incident laser intensities of up to 6 ×1015 W/cm2. The experiments investigated the interaction physics in various ablator materials (Be, C, CH, and SiO2) and under various beam-focusing conditions, which are relevant to developing a shock-ignition target design for the National Ignition Facility. The hot-electron production and the temperature of the distribution varied with the focal spot and beam overlap with values between 40 to 90 keV and instantaneous conversion efficiencies of laser power into hot-electron power of up to ~ 15%. A significant increase in hot-electron population was observed with CH ablators that was correlated with higher shock strength, exceeding 400 Mbar in the ablation layer and reaching Gbars upon convergence in the center of the spherical target. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

  15. Simulations of Converging Shock Collisions for Shock Ignition

    NASA Astrophysics Data System (ADS)

    Sauppe, Joshua; Dodd, Evan; Loomis, Eric

    2016-10-01

    Shock ignition (SI) has been proposed as an alternative to achieving high gain in inertial confinement fusion (ICF) targets. A central hot spot below the ignition threshold is created by an initial compression pulse, and a second laser pulse drives a strong converging shock into the fuel. The collision between the rebounding shock from the compression pulse and the converging shock results in amplification of the converging shock and increases the hot spot pressure above the ignition threshold. We investigate shock collision in SI drive schemes for cylindrical targets with a polystyrene foam interior using radiation-hydrodynamics simulations with the RAGE code. The configuration is similar to previous targets fielded on the Omega laser. The CH interior results in a lower convergence ratio and the cylindrical geometry facilitates visualization of the shock transit using an axial X-ray backlighter, both of which are important for comparison to potential experimental measurements. One-dimensional simulations are used to determine shock timing, and the effects of low mode asymmetries in 2D computations are also quantified. LA-UR-16-24773.

  16. Dual Mode Shock-Expansion/Reflected-Shock Tunnel

    NASA Technical Reports Server (NTRS)

    Erdos, John I.; Bakos, Robert J.; Castrogiovanni, Anthony; Rogers, R. Clayton

    1998-01-01

    NASA s HYPULSE facility at GASL has been reconfigured to permit free jet testing of the Hyper-X flowpath at flight Mach numbers of 7 and 10. Among the required changes are addition of a converging-diverging nozzle to permit operation in a reflected shock tunnel mode, a 7 ft. diameter test cabin and a 30 in. diameter contoured nozzle. However, none of these changes were allowed to interfere with rapid recovery of the prior shock-expansion tunnel mode of operation, and indeed certain changes should enhance facility usefulness and productivity in either mode. A previously-developed shock-induced detonation mode of driving the facility has been successfully applied to both reflected shock tunnel operation at Mach 10 flight conditions, with tailored interface operation, and shock-expansion tunnel operation at flight conditions corresponding to Mach numbers from 12 to 25. Tailored interface operation at Mach 7 has been achieved with an unheated helium driver. In the present paper, the rationale for a dual mode shock expansion/reflected shock tunnel is discussed, and the capabilities and limitations for each mode are outlined. The physical changes in the HYPULSE facility to achieve dual mode capability are also described. Limited calibration data obtained to date in the new reflected shock tunnel mode are presented and the anticipated flight simulation map with dual mode operation is also outlined.

  17. Grazing incidence beam expander

    NASA Astrophysics Data System (ADS)

    Akkapeddi, P. R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V. K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  18. Fast molecular shocks. II - Emission from fast dissociative shocks

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Dalgarno, A.

    1989-01-01

    The line radiations emitted in the cooling gas behind a fast dissociative shock are studied. The intensities emitted in high rotational transitions of the neutral molecules CO, SiO, HCN, CN, NO, and SO are estimated, as well as in rovibrational transitions of the molecular ions HeH(+) and OH(+) in radio recombination lines of atomic hydrogen and in fine-structure transitions of C, C(+), O, and Si(+). The predictions are compared with the observed intensities of line emission from the Orion-KL region. For Orion-KL the observations do not exclude, but probably do not require, the presence of a fast dissociative shock. Emission from SiO in high-J rotational states and from vibrationally excited OH(+), HeH(+), HeH(+), and SO(+) may be detectable from dissociative shocks under suitable conditions of preshock density and shock velocity; such emission may prove to be a useful diagnostic probe of fast shock activity.

  19. Formation of Chondrules by Shock Waves

    NASA Astrophysics Data System (ADS)

    Morris, M. A.; Boley, A. C.

    2017-02-01

    We describe and assess current shock models for chondrule formation, particularly those driven by gravitational disk instabilities and bow shocks. We discuss predictions made by shock models and further work needed.

  20. IPShocks: Database of Interplanetary Shock Waves

    NASA Astrophysics Data System (ADS)

    Isavnin, Alexey; Lumme, Erkka; Kilpua, Emilia; Lotti, Mikko; Andreeova, Katerina; Koskinen, Hannu; Nikbakhsh, Shabnam

    2016-04-01

    Fast collisionless shocks are one of the key interplanetary structures, which have also paramount role for solar-terrestrial physics. In particular, coronal mass ejection driven shocks accelerate particles to high energies and turbulent post-shock flows may drive intense geomagnetic storms. We present comprehensive Heliospheric Shock Database (ipshocks.fi) developed and hosted at University of Helsinki. The database contains currently over 2000 fast forward and fast reverse shocks observed by Wind, ACE, STEREO, Helios, Ulysses and Cluster spacecraft. In addition, the database has search and sort tools based on the spacecraft, time range, and several key shock parameters (e.g., shock type, shock strength, shock angle), data plots for each shock and data download options. These features allow easy access to shocks and quick statistical analyses. All current shocks are identified visually and analysed using the same procedure.

  1. Floating shock fitting via Lagrangian adaptive meshes

    NASA Technical Reports Server (NTRS)

    Vanrosendale, John

    1995-01-01

    In recent work we have formulated a new approach to compressible flow simulation, combining the advantages of shock-fitting and shock-capturing. Using a cell-centered on Roe scheme discretization on unstructured meshes, we warp the mesh while marching to steady state, so that mesh edges align with shocks and other discontinuities. This new algorithm, the Shock-fitting Lagrangian Adaptive Method (SLAM), is, in effect, a reliable shock-capturing algorithm which yields shock-fitted accuracy at convergence.

  2. How Culture Shock Affects Communication.

    ERIC Educational Resources Information Center

    Barna, LaRay M.

    The paper defines the term "culture shock" and discusses the changes that this state can make in a person's behavior. Culture shock refers to the emotional and physiological reaction of high activation that is brought about by sudden immersion in a new culture. Because one's own culture shields one from the unknown and reduces the need to make…

  3. [Management of pediatric septic shock].

    PubMed

    Llor, J; Parret, L; Stucki, P; Cotting, J

    2005-06-01

    Septic shock is a frequent admission cause in intensive care unit. In spite of the important progresses in the understanding of his physiopathology, mortality due to septic shock is about 20%. Recently, it has been demonstrated that an early goal-directed therapy permitted to improve the patient prognosis. With a good hemodynamic management and early antibiotherapy, mortality could be reduced.

  4. Molecular diagnostics of interstellar shocks

    NASA Astrophysics Data System (ADS)

    Hartquist, T. W.; Dalgarno, A.; Oppenheimer, M.

    1980-02-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km/sec. Substantial enhancements are predicted in the concentrations of the molecules H2S, SO, and SiO compared to those anticipated in cold interstellar clouds.

  5. The Efficacy of Cognitive Shock

    DTIC Science & Technology

    2015-05-21

    that allows military practitioners to operationalize cognitive shock against any given rival while experiencing diverse ecologies . 15. SUBJECT...operationalize cognitive shock against any given rival while experiencing diverse ecologies . iv Contents Acknowledgements...the emerging ecology rather than the more static concepts of force and control.8 This paper explores perception of depth and its potential

  6. Interpreting Shock Tube Ignition Data

    DTIC Science & Technology

    2003-10-01

    times only for high concentrations (of order 1% fuel or greater). The requirements of engine (IC, HCCI , CI and SI) modelers also present a different...Paper 03F-61 Interpreting Shock Tube Ignition Data D. F. Davidson and R. K. Hanson Mechanical Engineering ... Engineering Department Stanford University, Stanford CA 94305 Abstract Chemical kinetic modelers make extensive use of shock tube ignition data

  7. SPHERICAL SHOCK WAVES IN SOLIDS

    DTIC Science & Technology

    Contents: Introduction-Reasons for Studying Spherical Shock Waves, Physics of Cavity Expansion due to Explosive Impact, General Nature of Shock Waves...Governing Differential Equation of Self-Similar Motion; Application of the Theory of Self-Similar Motion to the Problem of Expansion of a Spherical

  8. Pin puller impact shock attenuation

    NASA Technical Reports Server (NTRS)

    Auclair, G. F.; Leonard, B. S.; Robbins, R. E.; Proffitt, W. L.

    1976-01-01

    Design of a pin arresting mechanism for a pyrotechnically actuated pin puller is reviewed. The investigative approach is discussed and the impact shock test results for various candidate designs are presented. The selected pin arresting design reduced the peak value of the shock response spectrum by five to one.

  9. Molecular diagnostics of interstellar shocks

    NASA Technical Reports Server (NTRS)

    Hartquist, T. W.; Dalgarno, A.; Oppenheimer, M.

    1980-01-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km/sec. Substantial enhancements are predicted in the concentrations of the molecules H2S, SO, and SiO compared to those anticipated in cold interstellar clouds.

  10. Shock profile induced by short laser pulses

    NASA Astrophysics Data System (ADS)

    Couturier, S.; de Rességuier, T.; Hallouin, M.; Romain, J. P.; Bauer, F.

    1996-06-01

    Standard 25-μm-thick polyvinilydene fluoride (PVDF) piezoelectric gauges and new 450-μm-thick P(VDF 70%, TrFE 30%) piezoelectric copolymer have been used to record shock profiles at the back face of metallic targets irradiated by laser pulses of 2.5 and 0.6 ns duration at a 1.06 μm wavelength. The records are fully explained with simplified space-time diagram analysis. The pressure profile applied at the front face of the target has been determined from these records combined with numerical simulations of wave propagation through the target. A numerical code describing the interaction of laser with matter (FILM) has also been used for computing the applied pressure. Both methods lead to very close results. The peak pressure dependence on incident laser intensity is determined up to 30 GPa at 1012 W/cm2.

  11. Understanding sepsis: from SIRS to septic shock.

    PubMed

    Hynes-Gay, Patricia; Lalla, Patti; Leo, Maria; Merrill-Bell, Audrey; Nicholson, Marjorie; Villaruel, Elizabeth

    2002-01-01

    Sepsis remains the leading cause of death in non-coronary ICU patients, despite improvements in supportive treatment modalities such as antimicrobial drugs and ventilation therapy. Further, the incidence of sepsis is projected to increase in years to come, related to factors including a rise in immunosuppressed patient populations and more widespread use of invasive lines and procedures. In this article, the authors seek to advance nurses' understanding of sepsis by reviewing the SIRS to septic shock paradigm and using a case study to illustrate how a patient progressed along the continuum. The role of the critical care nurse is an important aspect of the care of these patients. Early identification of patients at risk for, or who are developing, sepsis is crucial in order to improve patient outcomes.

  12. Augmented Shock Wave Severance of Materials

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Schimmel, Morry L.

    1995-01-01

    This paper describes a new approach for severing or weakening a variety of materials. The technique employs embedding explosive cords into parallel grooves that are cut into a surface of a material. The cords are initiated simultaneously to produce shock waves that progress toward the centerline between the cords and the lower surface of the material. Intersecting incident and reflected waves augment at the centerline to fail or weaken the material in tension. No harmful debris is produced on the opposite side of the material from the explosive cords. The primary focus of the effort described in this paper was to fracture the F-16 aircraft trilaminate canopy. Also, complete severance was achieved in 2024-T4 aluminum plate stock. Possible applications are through canopy egress and crew module severance from military aircraft and separation of rocket vehicle stages and payloads. This approach offers important advantages over explosive methods currently in use.

  13. Location Estimation of the Bow Shock and Theta angle (B, n) cuasiperpendicular magnetospheric, using data from 14 different events crossings shock recorded by THEMIS-C.

    NASA Astrophysics Data System (ADS)

    Amazo-Gomez, Eliana; Alvarado-Gomez, Julian David; Calvo Mozo, Benjamin

    In this Work we calculated the average position of the bow shock, through the eigenvalues ​​and corresponding eigenvectors of the covariance matrix for the magnetic field developed from 10 different crosses shock events recorded by THEMIS A, during the years 2009 and 2010. With data obtained from previous calibration and the propagation direction of the magnetic field of the plasma is able to find the interaction quasi perpendicular angle Theta (B,n) which depends on the direction normal shock and the direction of incidence of field magnetic plasma. The importance of this type of analysis is that the understanding of the phenomenology of the bow shock, which is vital for the characterization of processes such as magnetic reconnection between magnetospheric lines terrestrial and interplanetary field lines carrying a large contribution from the Sun apparently lines will also be important for the description of how to enter the plasma charged particles from impacting the bow shock to the internal field lines to these particles subsequently lead to the Earth's atmosphere, these initially enter through the polar region (Polar Cusp) and then disseminated depending on the conditions of the plasma into the Earth's atmosphere , and parameters such as the position of the bow shock, this variation and interaction angle Theta (B,n) are basic to reach a minimal representation of the phenomenon. In events of great magnitude can have undesirable effects on satellites, power lines, communications and air travel, the latter is the interest on discrimination of some parameters of the phenomenon presented in this work. The study of the Bow shock, bow shock and Magnetospheric has as its starting point a detailed description of Earth's magnetosphere and solar wind phenomena must be understood independently initially and then trying to relate in terms of their interaction and communion in their respective limits, parameters such as the balance between dynamic and magnetic pressure

  14. Shock temperatures in anorthite glass

    NASA Technical Reports Server (NTRS)

    Boslough, M. B.; Ahrens, T. J.; Mitchell, A. C.

    1983-01-01

    Temperatures of CaAl2Si2O8 (anorthite glass) shocked to pressures between 48 and 117 GPa were measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high pressure phase. At least three phase transitions, at pressures of about 55, 85, and 100 GPa and with transition energies of about 0.5 MJ/kg each (approximately 1.5 MJ/kg total) are required to explain the shock temperature data. The phase transition at 100 GPa can possibly be identified with the stishovite melting transition. Theoretical models of the time dependence of the thermal radiation from the shocked anorthite based on the geometry of the experiment and the absorptive properties of the shocked material yields good agreement with observations, indicating that it is not necessary to invoke intrinsic time dependences to explain the data in many cases.

  15. Shock waves in polycrystalline iron.

    PubMed

    Kadau, Kai; Germann, Timothy C; Lomdahl, Peter S; Albers, Robert C; Wark, Justin S; Higginbotham, Andrew; Holian, Brad Lee

    2007-03-30

    The propagation of shock waves through polycrystalline iron is explored by large-scale atomistic simulations. For large enough shock strengths the passage of the wave causes the body-centered-cubic phase to transform into a close-packed phase with most structure being isotropic hexagonal-close-packed (hcp) and, depending on shock strength and grain orientation, some fraction of face-centered-cubic (fcc) structure. The simulated shock Hugoniot is compared to experiments. By calculating the extended x-ray absorption fine structure (EXAFS) directly from the atomic configurations, a comparison to experimental EXAFS measurements of nanosecond-laser shocks shows that the experimental data is consistent with such a phase transformation. However, the atomistically simulated EXAFS spectra also show that an experimental distinction between the hcp or fcc phase is not possible based on the spectra alone.

  16. Tables and charts of equilibrium normal shock and shock tube solutions for pure CO2 with velocities to 16 km/second

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Wilder, S. E.

    1974-01-01

    Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2, representative of Mars and Venus atmospheres. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 Newtons per square meter to 500 kilo Newtons per square meter. The present results are applicable to shock tube flows, and to free-flight conditions for a blunt body at high velocities. Working charts illustrating idealized shock-tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.

  17. Table and charts of equilibrium normal-shock and shock-tube properties for pure carbon dioxide with velocities from 1 to 16 km/sec

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Wilder, S. E.

    1976-01-01

    Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 N/sq m to 500 kN/sq m. The present results are applicable to shock tube flows and to freeflight conditions for a blunt body at high velocities. Working charts illustrating idealized shock tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.

  18. Delay Adjusted Incidence

    Cancer.gov

    This Infographic shows the National Cancer Institute SEER Incidence Trends. The graphs show the Average Annual Percent Change (AAPC) 2002-2011. For Men, Thyroid: 5.3*,Liver & IBD: 3.6*, Melanoma: 2.3*, Kidney: 2.0*, Myeloma: 1.9*, Pancreas: 1.2*, Leukemia: 0.9*, Oral Cavity: 0.5, Non-Hodgkin Lymphoma: 0.3*, Esophagus: -0.1, Brain & ONS: -0.2*, Bladder: -0.6*, All Sites: -1.1*, Stomach: -1.7*, Larynx: -1.9*, Prostate: -2.1*, Lung & Bronchus: -2.4*, and Colon & Rectum: -3/0*. For Women, Thyroid: 5.8*, Liver & IBD: 2.9*, Myeloma: 1.8*, Kidney: 1.6*, Melanoma: 1.5, Corpus & Uterus: 1.3*, Pancreas: 1.1*, Leukemia: 0.6*, Brain & ONS: 0, Non-Hodgkin Lymphoma: -0.1, All Sites: -0.1, Breast: -0.3, Stomach: -0.7*, Oral Cavity: -0.7*, Bladder: -0.9*, Ovary: -0.9*, Lung & Bronchus: -1.0*, Cervix: -2.4*, and Colon & Rectum: -2.7*. * AAPC is significantly different from zero (p<.05). Rates were adjusted for reporting delay in the registry. www.cancer.gov Source: Special section of the Annual Report to the Nation on the Status of Cancer, 1975-2011.

  19. Shock induced cavity collapse

    NASA Astrophysics Data System (ADS)

    Skidmore, Jonathan; Doyle, Hugo; Tully, Brett; Betney, Matthew; Foster, Peta; Ringrose, Tim; Ramasamy, Rohan; Parkin, James; Edwards, Tom; Hawker, Nicholas

    2016-10-01

    Results from the experimental investigation of cavity collapse driven by a strong planar shock (>6km/s) are presented. Data from high speed framing cameras, laser backlit diagnostics and time-resolved pyromety are used to validate the results of hydrodynamic front-tracking simulations. As a code validation exercise, a 2-stage light gas gun was used to accelerate a 1g Polycarbonate projectile to velocities exceeding 6km/s; impact with a PMMA target containing a gas filled void results in the formation of a strong shockwave with pressures exceeding 1Mbar. The subsequent phenomena associated with the collapse of the void and excitation of the inert gas fill are recorded and compared to simulated data. Variation of the mass density and atomic number of the gas fill is used to alter the plasma parameters furthering the extent of the code validation.

  20. [Vasopressin use in shock].

    PubMed

    Carrillo-Esper, Raúl; González-Salazar, Jorge A; Calvo-Carrillo, Benjamín

    2004-01-01

    Arginine-vasopressin (VP), also known as the antidiuretic hormone, is essential for water homeostasis. Its synthesis and liberation depends on regulation of osmotic, hypovolemic, hormonal, and nonosmotic stimuli. It has been demonstrated that it is key for maintenance of cardiovascular homeostasis through vasomotor regulation, the determinant of systemic vascular resistance and mean arterial pressure, a process acting through V1 receptors. Shock state with refractory vasodilation seen in sepsis, systemic inflammatory response, hypovolemia, cardiac arrest, polytrauma, etc., is characterized by an initial phase of liberation and increased levels of VP followed by a second phase characterized by inappropriately low levels of this hormone that are associated with refractoriness to management with volume, inotropics, and vasopressors. It has been demonstrated in clinical and experimental studies that exogenous VP treatment under this condition increases systemic vascular resistance, perfusion pressure, and oxygen supply to peripheral tissues, which makes it possible to decrease and to suspend vasopressors and also to increase survival.

  1. Dengue shock syndrome

    PubMed Central

    Sudulagunta, Sreenivasa Rao; Sodalagunta, Mahesh Babu; Sepehrar, Mona; Bangalore Raja, Shiva Kumar; Nataraju, Aravinda Settikere; Kumbhat, Mounica; Sathyanarayana, Deepak; Gummadi, Siddharth; Burra, Hemanth Kumar

    2016-01-01

    Dengue fever is a mosquito-borne arthropod-borne viral (arboviral) tropical disease in humans affecting 50–528 million people worldwide. The acute abdominal complications of dengue fever are acute appendicitis, acute pancreatitis, acute acalculous cholecystitis and non-specific peritonitis. Acute pancreatitis with new onset diabetes in dengue shock syndrome (DSS) is very rarely reported. We describe a case of 30-year-old man admitted in intensive care unit and was diagnosed with DSS with RT-PCR, NS1 antigen and dengue IgM antibody being positive. Abdominal ultrasound and computerized tomography confirmed acute pancreatitis. Patient required insulin after recovery. Diabetes mellitus caused by DSS is under-reported and lack of awareness may increase mortality and morbidity. PMID:28031845

  2. Diffusive shock acceleration - comparison of a unified shock model to bow shock observations

    SciTech Connect

    Ellison, D.C.; Moebius, E.

    1987-07-01

    A comparison is made between recent AMPTE/IRM observations of diffuse ions detected upstream of the earth's bow shock when the interplanetary magnetic field was nearly parallel to the solar wind direction and a known collisionless quasi-parallel shock model. These observations, which provide the proton spectrum for all of velocity space, give a direct measure of the shock acceleration efficiency and show how thermal solar winds are injected into the diffusive shock acceleration mechanism. The model accurately describes the proton spectrum; moreover, it predicts the shock structure, the complete particle spectrum, the relative velocity distributions of different ion species in the down stream region, and the enhancement of heavy ions over protons relative to the unshocked solar wind. 68 references.

  3. Diffusive shock acceleration - Comparison of a unified shock model to bow shock observations

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.; Moebius, Eberhard

    1987-01-01

    A comparison is made between recent AMPTE/IRM observations of diffuse ions detected upstream of the earth's bow shock when the interplanetary magnetic field was nearly parallel to the solar wind direction and a known collisionless quasi-parallel shock model. These observations, which provide the proton spectrum for all of velocity space, give a direct measure of the shock acceleration efficiency and show how thermal solar winds are injected into the diffusive shock acceleration mechanism. The model accurately describes the proton spectrum; moreover, it predicts the shock structure, the complete particle spectrum, the relative velocity distributions of different ion species in the down stream region, and the enhancement of heavy ions over protons relative to the unshocked solar wind.

  4. Shock propagation and the generation of magnetohydrodynamic wave fields in inhomogeneous molecular clouds

    NASA Technical Reports Server (NTRS)

    Miesch, Mark S.; Zweibel, Ellen G.

    1994-01-01

    We develop a simple one-dimensional model for the interaction of a steady, thin, planar shock wave with a nonrigid cloud which may be in motion relative to the surrounding medium, and we apply the model to shocks impinging on, and propagating through, molecular clouds. Both 'adiabatic' (gamma = 5/3) and radiative (gamma = 1) shocks are considered and we allow for the presence of a uniform magnetic field directed either parallel or perpendicular to the shock normal. The former field orientation is equivalent to the hydrodynamic case, and the latter involves only fast MHD shocks. We focus on the manner in which such shocks can generate internal kinetic motions in the cloud on a range of size and density scales through the direct acceleration of cores and clumps by shocks transmitted into them and through the generation of an MHD wavefield via the reflection of the incident shock at clump boundaries. We find that stronger incident Mach numbers and smaller density contrasts lead to more efficient cloud acceleration, as do isothermal intercloud shocks and small intercloud magnetic field strengths. The acceleration efficiency is insensitive to the adiabatic index and the magnetic field strength in the cloud itself. For typical parameter choices, the direct acceleration of clouds and clumps by strong shocks is found to be substantial and could at least in part account for their observed velocity dispersions. If the shocks are moderately weak, the final velocity of the cloud is linearly related to its initial velocity, with higher acceleration giving shallower slopes (i.e., final velocity distributions which are less sensitive to the initial distribution). Compared to the kinetic energy of the postshock cloud, the energy given to the wavefield at each encounter is small, and the heating of the interclump medium by the dissipation of this wavefield is found to be insufficient to balance the cooling rate in the cloud as a whole (although it may be important in particular

  5. Chondrule Destruction in Nebular Shocks

    NASA Astrophysics Data System (ADS)

    Jacquet, Emmanuel; Thompson, Christopher

    2014-12-01

    Chondrules are millimeter-sized silicate spherules ubiquitous in primitive meteorites, but whose origin remains mysterious. One of the main proposed mechanisms for producing them is melting of solids in shock waves in the gaseous protoplanetary disk. However, evidence is mounting that chondrule-forming regions were enriched in solids well above solar abundances. Given the high velocities involved in shock models, destructive collisions would be expected between differently sized grains after passage of the shock front as a result of differential drag. We investigate the probability and outcome of collisions of particles behind a one-dimensional shock using analytic methods as well as a full integration of the coupled mass, momentum, energy, and radiation equations. Destruction of protochondrules seems unavoidable for solid/gas ratios epsilon >~ 0.1, and possibly even for solar abundances because of "sandblasting" by finer dust. A flow with epsilon >~ 10 requires much smaller shock velocities (~2 versus 8 km s-1) in order to achieve chondrule-melting temperatures, and radiation trapping allows slow cooling of the shocked fragments. Initial destruction would still be extensive; although re-assembly of millimeter-sized particles would naturally occur by grain sticking afterward, the compositional heterogeneity of chondrules may be difficult to reproduce. We finally note that solids passing through small-scale bow shocks around few kilometer-sized planetesimals might experience partial melting and yet escape fragmentation.

  6. Literature analysis of Acanthopanax anaphylactic shock in China

    PubMed Central

    Zhan, Qian

    2015-01-01

    The aims of this study are to investigate the occurrence characteristics of Acanthopanax (刺五加 cì wǔ jiā) anaphylactic shock and to provide objective evidence for the rational use of the medicine. Fifty-seven cases of Acanthopanax anaphylactic shock were collected from several professional databases in China. The statistical data of the patients were analyzed with Visual FoxPro 6.0 and Office Excel 2003 by Microsoft (Redmond, WA, USA). The male:female incidence ratio was 0.5:1. Fifty-six (98.25%) patients were older than 30 years. Thirty-nine (68.42%) patients had an unknown allergy history. Nine (15.79%) patients used Acanthopanax for unlabeled indications. In most (98.25 %) patients, Acanthopanax was used in the form of dosage injection. Anaphylactic shock occurred within 30 minutes after treatment in 52 (94.54%) patients, and all episodes occurred during the infusion process. In two (3.51%) patients, the episode occurred when they used Acanthopanax for the second time. In one (1.75%) patient, the episode occurred during the third time of use. The clinical symptoms of anaphylactic shock are diversified, but all patients presented with cardiovascular and respiratory system symptoms. Acanthopanax injections that led to anaphylactic shock were produced exclusively by four manufacturers. Four (7.02%) patients died and 49 (85.96%) patients were cured, but the status of four patients is unknown. Because an Acanthopanax injection may cause anaphylactic shock and can be fatal in severe cases, physicians and patients must pay close attention to using it rationally. Clinicians should carefully consult the allergic constitution of their patients, strictly follow the guidelines of the drug, use Acanthopanax in the oral dosage form as much as possible, and strengthen therapeutic monitoring. PMID:26587397

  7. Slow shocks around the sun

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1982-01-01

    It is inferred from this study that magnetohydrodynamic slow shocks can exist in the vicinity of the sun. The study uses a two-hole corona model, the sub-Alfvenic streams originating from the edge of the polar open-field regions are forced to turn towards equator in coronal space following the curved boundary of the closed field region. When the streamlines from the opposite poles merge at a neutral point, their directions become parallel to the neutral sheet. An oblique slow shock can develop near or at the neutral point, the shock extends polewards to form a surface of discontinuity around the sun.

  8. Is this septic shock? A rare case of distributive shock.

    PubMed

    Val-Flores, Luis Silva; Fior, Alberto; Santos, Ana; Reis, Luís; Bento, Luís

    2014-01-01

    The authors report a rare case of shock in a patient without significant clinical history, admitted to the intensive care unit for suspected septic shock. The patient was initially treated with fluid therapy without improvement. A hypothesis of systemic capillary leak syndrome was postulated following the confirmation of severe hypoalbuminemia, hypotension, and hemoconcentration--a combination of three symptoms typical of the disease. The authors discussed the differential diagnosis and also conducted a review of the diagnosis and treatment of the disease.

  9. Is this septic shock? A rare case of distributive shock

    PubMed Central

    Val-Flores, Luis Silva; Fior, Alberto; Santos, Ana; Reis, Luís; Bento, Luís

    2014-01-01

    The authors report a rare case of shock in a patient without significant clinical history, admitted to the intensive care unit for suspected septic shock. The patient was initially treated with fluid therapy without improvement. A hypothesis of systemic capillary leak syndrome was postulated following the confirmation of severe hypoalbuminemia, hypotension, and hemoconcentration - a combination of three symptoms typical of the disease. The authors discussed the differential diagnosis and also conducted a review of the diagnosis and treatment of the disease. PMID:25607273

  10. Toxic shock syndrome: an opportunity for nursing intervention.

    PubMed

    Creehan, P A

    1995-01-01

    Toxic Shock Syndrome (TSS) is a potentially fatal illness caused by a particular strain of Staphylococcus aureus. The clinical presentation is similar to that of septic shock. The incidence of TSS peaked in the late 1970s and early 1980s, probably as a result of availability of super absorbent tampons. Although most commonly associated with menstruation, the overall incidence of menstrual and nonmenstrual TSS in men and women ranges from 1 to 3 per 100,000. There are almost equal numbers of menstrual and nonmenstrual cases of TSS identified annually. S aureus, the causative microorganism in cases of TSS, has been isolated from many body tissues. Toxic shock syndrome presents as a flu-like illness with high fever, vomiting, diarrhea, general malaise, and muscle weakness. Nursing and medical management focus on controlling or preventing potentially serious complications, such as adult respiratory distress syndrome, renal failure, electrolyte imbalances, disseminated intravascular coagulation, encephalopathy, and cardiomyopathy. Judicious use of tampons and barrier contraceptive devices may decrease the risk of developing TSS.

  11. Altitude Modulates Concussion Incidence

    PubMed Central

    Smith, David W.; Myer, Gregory D.; Currie, Dustin W.; Comstock, R. Dawn; Clark, Joseph F.; Bailes, Julian E.

    2013-01-01

    Background: Recent research indicates that the volume and/or pressure of intracranial fluid, a physiology affected by one’s altitude (ie, elevation above sea level), may be associated with the likelihood and/or severity of a concussion. The objective was to employ an epidemiological field investigation to evaluate the relationship between altitude and concussion rate in high school sports. Hypothesis: Because of the physiologies that occur during acclimatization, including a decline in intracranial compliance (a “tighter fit”), increased altitude may be related to a reduction in concussion rates in high school athletes. Study Design: Cohort study; Level of evidence, 3. Methods: Data on concussions and athlete exposures (AEs) between 2005-2006 and 2011-2012 were obtained from a large national sample of high schools (National High School Sports-Related Injury Surveillance System [High School RIO]) and were used to calculate total, competition, and practice concussion rates for aggregated sports and for football only. Results: Altitude of participating schools ranged from 7 to 6903 ft (median, 600 ft), and a total of 5936 concussions occurred in 20,618,915 exposures (2.88 per 10,000 AEs). When concussion rates were dichotomized by altitude using the median, elevated altitude was associated with a reduction in concussion rates overall (rate ratio [RR], 1.31; P < .001), in competition (RR, 1.31; P < .001), and in practice (RR, 1.29; P < .001). Specifically, high school sports played at higher altitude demonstrated a 31% reduction (95% confidence interval [CI], 25%-38%) in the incidence of total reported concussions. Likewise, concussion rates at increased altitude were reduced 30% for overall exposures, 27% for competition exposures, and 28% for practice exposures in football players (P < .001). Conclusion: The results of this epidemiological investigation indicate increased physiological responses to altitude may be associated with a reduction in sports

  12. Quasilinear simulations of interplanetary shocks and Earth's bow shock

    NASA Astrophysics Data System (ADS)

    Afanasiev, Alexandr; Battarbee, Markus; Ganse, Urs; Vainio, Rami; Palmroth, Minna; Pfau-Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

    2016-04-01

    We have developed a new self-consistent Monte Carlo simulation model for particle acceleration in shocks. The model includes a prescribed large-scale magnetic field and plasma density, temperature and velocity profiles and a self-consistently computed incompressible ULF foreshock under the quasilinear approximation. Unlike previous analytical treatments, our model is time dependent and takes full account of the anisotropic particle distributions and scattering in the wave-particle interaction process. We apply the model to the problem of particle acceleration at traveling interplanetary (IP) shocks and Earth's bow shock and compare the results with hybrid-Vlasov simulations and spacecraft observations. A qualitative agreement in terms of spectral shape of the magnetic fluctuations and the polarization of the unstable mode is found between the models and the observations. We will quantify the differences of the models and explore the region of validity of the quasilinear approach in terms of shock parameters. We will also compare the modeled IP shocks and the bow shock, identifying the similarities and differences in the spectrum of accelerated particles and waves in these scenarios. The work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support. We acknowledge the computational resources provided by CSC - IT Centre for Science Ltd., Espoo.

  13. Rarefaction shock in the near wake

    NASA Technical Reports Server (NTRS)

    Diebold, D.; Hershkowitz, N.; Eliezer, S.

    1987-01-01

    Laboratory experiments and fluid theory find a stationary rarefaction shock in the near wake of an electrically grounded obstacle placed in a steady state, supersonic plasma flow. The shock is only found when two electron temperatures, differing by at least an order of magnitude, are present. These shocks are analogous to rarefaction shocks in plasma free expansions.

  14. An introduction to shaker shock simulations

    SciTech Connect

    Rogers, J.D.

    1989-01-01

    The use of shakers in shock testing is addressed. A brief review of the shock response spectrum is given with its applications to test specification. The capabilities and limitations of shaker shock simulations are discussed with regard to both classical pulses and transient vibration inputs. Methods for performing shaker shock simulations are presented. 21 refs., 4 figs., 1 tab.

  15. Observations of Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Koval, A.; Szabo, Adam; Breneman, A.; Cattell, C. A.; Goetz, K.; Kellogg, P. J.; Kersten, K.; Kasper, J. C.; Maruca, B. A.; Pulupa, M.

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. They have rest frame frequencies f(sub ci) < f much < f(sub ce) and wave numbers 0.02 approx < k rho (sub ce) approx <. 5.0. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves. Al though the precursors can have delta B/B(sub o) as large as 2, fluxgate magnetometer measurements show relatively laminar shock transitions in three of the four events.

  16. Harnessing Critical Incidents for Learning

    ERIC Educational Resources Information Center

    Patahuddin, Sitti Maesuri; Lowrie, Tom

    2015-01-01

    A critical incident is a situation or event that holds significance for learning, both for the students and teachers. This paper presents four examples of critical incidents from a Year 7 teacher's lesson excerpts in Indonesia involving teaching of fractions, to show how they shaped classroom situation, brought forward elements of conflict, and…

  17. How Is Cardiogenic Shock Treated?

    MedlinePlus

    ... muscle contracts Treat a heart attack Medical Devices Medical devices can help the heart pump and improve blood flow. Devices used to treat cardiogenic shock may include: An intra-aortic balloon pump. This device is placed in the aorta, ...

  18. Shocks in the Early Universe

    NASA Astrophysics Data System (ADS)

    Pen, Ue-Li; Turok, Neil

    2016-09-01

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1 GeV shock formation and the consequent gravitational wave emission provide a signal detectable by current and planned gravitational wave experiments, allowing them to strongly constrain conditions present in the primordial Universe as early as 10-30 sec after the big bang.

  19. Shock Isolation on Planet Mars

    NASA Astrophysics Data System (ADS)

    Kletz, Bjorn T.; Melcher, Jorg

    2014-06-01

    In 2016 the 'InSight' mission will be launched towards planet Mars. Within parts of this mission, sensitive electronics have to be isolated for occurring shocks, as these components are hammered into the Martian soil. A mechanical shock isolation interface - that is based on patented double spiral springs - is integrated into the hammering structure to protect the integrated electronics from the harmful peak accelerations.This paper starts with introducing the theoretical background for the development of such devices and continues with the description and analysis of the actually implemented interface version. Additionally, this paper describes the used mechanism to protect the system during launch. Measurements during the hammering process and the penetration of Mars-like soil prove the effectiveness of the described shock isolation device in real conditions. Finally, this paper highlights the achieved extreme shock reduction performance that reduces the critical accelerations by factor 127 with this novel device.

  20. Shock compression of liquid hydrazine

    SciTech Connect

    Garcia, B.O.; Chavez, D.J.

    1996-05-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used for aerospace propulsion and power systems. Because the propellant modules can be subject to debris impacts during their use, the shock states that can occur in the hydrazine need to be characterized to safely predict its response. Several shock compression experiments have been conducted to investigate the shock detonability of liquid hydrazine; however, the experiments{close_quote} results disagree. Therefore, in this study, we reproduced each experiment numerically to evaluate in detail the shock wave profiles generated in the liquid hydrazine. This paper presents the results of each numerical simulation and compares the results to those obtained in experiment. {copyright} {ital 1996 American Institute of Physics.}

  1. Rayleigh-Taylor Shock Waves

    SciTech Connect

    Olson, B J; Cook, A W

    2007-08-30

    Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These shocklets coalesce in multidimensional fashion into a strong normal shock, which increases in strength as it propagates upwards. Large-eddy simulations demonstrate that the shock Mach number increases faster in three dimensions than it does in two dimensions. The generation of shocks via Rayleigh-Taylor instability could have profound implications for astrophysical flows.

  2. Undercuts by Laser Shock Forming

    SciTech Connect

    Wielage, Hanna; Vollertsen, Frank

    2011-05-04

    In laser shock forming TEA-CO{sub 2}-laser induced shock waves are used to form metal foils, such as aluminum or copper. The process utilizes an initiated plasma shock wave on the target surface, which leads to a forming of the foil. A challenge in forming technologies is the manufacturing of undercuts. By conventional forming methods these special forms are not feasible. In this article, it is presented that undercuts in the micro range can be produced by laser shock deep drawing. Different drawing die diameters, drawing die depths and the material aluminum in the thicknesses 20 and 50 {mu}m were investigated. It will be presented that smaller die diameters facilitate undercuts compared to bigger die diameters. The phenomena can be explained by Barlow's formula. Furthermore, it is shown which maximum undercut depth at different die diameters can be reached. To this end, cross-sections of the different parameter combinations are displayed.

  3. Shocks in the Early Universe.

    PubMed

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVshock formation and the consequent gravitational wave emission provide a signal detectable by current and planned gravitational wave experiments, allowing them to strongly constrain conditions present in the primordial Universe as early as 10^{-30}  sec after the big bang.

  4. Stability of undercompressive shock profiles

    NASA Astrophysics Data System (ADS)

    Howard, Peter; Zumbrun, Kevin

    Using a simplified pointwise iteration scheme, we establish nonlinear phase-asymptotic orbital stability of large-amplitude Lax, undercompressive, overcompressive, and mixed under-overcompressive type shock profiles of strictly parabolic systems of conservation laws with respect to initial perturbations |u(x)|⩽E(1 in C, E sufficiently small, under the necessary conditions of spectral and hyperbolic stability together with transversality of the connecting profile. This completes the program initiated by Zumbrun and Howard in [K. Zumbrun, P. Howard, Pointwise semigroup methods and stability of viscous shock waves, Indiana Univ. Math. J. 47 (4) (1998) 741-871], extending to the general undercompressive case results obtained for Lax and overcompressive shock profiles in [A. Szepessy, Z. Xin, Nonlinear stability of viscous shock waves, Arch. Ration. Mech. Anal. 122 (1993) 53-103; T.-P. Liu, Pointwise convergence to shock waves for viscous conservation laws, Comm. Pure Appl. Math. 50 (11) (1997) 1113-1182; K. Zumbrun, P. Howard, Pointwise semigroup methods and stability of viscous shock waves, Indiana Univ. Math. J. 47 (4) (1998) 741-871; K. Zumbrun, Refined wave-tracking and nonlinear stability of viscous Lax shocks, Methods Appl. Anal. 7 (2000) 747-768; M.-R. Raoofi, L-asymptotic behavior of perturbed viscous shock profiles, thesis, Indiana Univ., 2004; C. Mascia, K. Zumbrun, Pointwise Green's function bounds and stability of relaxation shocks, Indiana Univ. Math. J. 51 (4) (2002) 773-904; C. Mascia, K. Zumbrun, Stability of small-amplitude shock profiles of symmetric hyperbolic-parabolic systems, Comm. Pure Appl. Math. 57 (7) (2004) 841-876; C. Mascia, K. Zumbrun, Pointwise Green's function bounds for shock profiles with degenerate viscosity, Arch. Ration. Mech. Anal. 169 (3) (2003) 177-263; C. Mascia, K. Zumbrun, Stability of large-amplitude shock profiles of hyperbolic-parabolic systems, Arch. Ration. Mech. Anal. 172 (1) (2004) 93-131; C. Mascia, K. Zumbrun

  5. Dehydration kinetics of shocked serpentine

    NASA Technical Reports Server (NTRS)

    Tyburczy, James A.; Ahrens, Thomas J.

    1988-01-01

    Experimental rates of dehydration of shocked and unshocked serpentine were determined using a differential scanning calorimetric technique. Dehydration rates in shocked serpentine are enhanced by orders of magnitude over corresponding rates in unshocked material, even though the impact experiments were carried out under conditions that inhibited direct impact-induced devolatilization. Extrapolation to temperatures of the Martian surface indicates that dehydration of shocked material would occur 20 to 30 orders of magnitude more rapidly than for unshocked serpentine. The results indicate that impacted planetary surfaces and associated atmospheres would reach chemical equilibrium much more quickly than calculations based on unshocked material would indicate, even during the earliest, coldest stages of accretion. Furthermore, it is suggested that chemical weathering of shocked planetary surfaces by solid-gas reactions would be sufficiently rapid that true equilibrium mineral assemblages should form.

  6. 'Shocking' Obedience Found in Children

    ERIC Educational Resources Information Center

    Science News, 1977

    1977-01-01

    Describes a Stanley Milgram type obedience experiment conducted with 192 Jordanian children ages 6-16. Seventy-three percent of the children responded via administering supposed dangerous electrical shocks to test subjects. (SL)

  7. Shock metamorphism of granulated lunar basalt

    NASA Technical Reports Server (NTRS)

    Schaal, R. B.; Thompson, T. D.; Hoerz, F.; Bauer, J. F.

    1979-01-01

    The paper deals with an extensive series of shock-recovery experiments performed on both nonporous crystalline basalt and its granulated and sieved counterpart to study the role of porosity and grain size in shock motomorphic effects under otherwise identical conditions. Shocked samples are compared with unshocked starting material in terms of textural and mineralogical modifications attributable to shock. A comparative petrographic and chemical characterization is presented of pulverized and sieved lunar basalt 75035 shocked between 6 and 75 GPa in comparison with holocrystalline disks of the same basalts shocked in 10 earlier experiments. Specifically, a petrographic classification of shock features is given, along with an estimation of relative amounts of shock glasses and a chemical characterization of shock glasses in each shocked granular basalt.

  8. Turbulence in electrostatic ion acoustic shocks

    NASA Technical Reports Server (NTRS)

    Means, R. W.; Coroniti, F. V.; Wong, A. Y.; White, R. B.

    1973-01-01

    Three types of collisionless electrostatic ion acoustic shocks are investigated using a double plasma (DP) device: (1) laminar shocks; (2) small amplitude turbulent shocks in which the turbulence is confined to be upstream of the shock potential jump; and (3) large amplitude turbulent shocks in which the wave turbulence occurs throughout the shock transition. The wave turbulence is generated by ions which are reflected from the shock potential; linear theory spatial growth increments agree with experimental values. The experimental relationship between the shock Mach number and the shock potential is shown to be inconsistent with theoretical shock models which assume that the electrons are isothermal. Theoretical calculations which assume a trapped electron equation of a state and a turbulently flattened velocity distrubution function for the reflected ions yields a Mach number vs potential relationship in agreement with experiment.

  9. [Emergency medicine at the limit: shock-, analgesic therapy and airway management in difficult terrain].

    PubMed

    Rauch, Simon; Schenk, Kai; Rainer, Bernhard; Strapazzon, Giacomo; Paal, Peter; Brugger, Hermann

    2016-01-01

    Rescue operations in mountain and remote areas pose special challenges for the rescue team and often differ substantially from rescue missions in the urban environment. Given the growing sports and leisure activities in mountains, incidence of alpine emergencies is expected to rise further. The following article describes the treatment of haemorrhagic shock, analgesic therapy and airway management in mountain rescue.

  10. Shock waves show icebreaking promise

    SciTech Connect

    Wesley, R.H.; Stowell, W.R.

    1985-11-01

    State-of-the-art technology that is readily applicable in other offshore areas does not function adequately in Arctic regions. The common offshore problem in the Arctic, whether it be related to transportation, construction, drilling or production, is ice. Technology utilizing the phenomenal characteristics of the shock wave now exists that will allow relief from the ice problem in all of these categories. The feasibility of using shock waves for icebreaking is discussed.

  11. Shock phenomena in interplanetary space

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1972-01-01

    The performance of the solar wind near one astronomical unit is discussed. The solar wind is shown to act as a compressible, supersonic, magnetogasdynamic fluid. The creation of magnetogasdynamic shock waves by solar flares and other causes is analyzed. The observations of shock fronts and the flows behind these fronts are discussed and synoptic views of the observations are described. Theoretical concepts and models are summarized.

  12. Theoretical Insight into Shocked Gases

    SciTech Connect

    Leiding, Jeffery Allen

    2016-09-29

    I present the results of statistical mechanical calculations on shocked molecular gases. This work provides insight into the general behavior of shock Hugoniots of gas phase molecular targets with varying initial pressures. The dissociation behavior of the molecules is emphasized. Impedance matching calculations are performed to determine the maximum degree of dissociation accessible for a given flyer velocity as a function of initial gas pressure.

  13. Shock compression of precompressed deuterium

    SciTech Connect

    Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F; Militzer, B

    2011-07-31

    Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.

  14. Particle acceleration at collisionless shocks: An overview

    SciTech Connect

    Zank, G.P.; Li Gang; Webb, G.M.; Le Roux, J.A.; Florinski, V.; Ao, X.; Rice, W.K.M.

    2005-08-01

    An overview of shock acceleration is presented, focusing primarily on interplanetary shocks and the termination shock as examples. An extended discussion of recent advances in modeling real solar energetic particle (SEP) and energetic storm particle (ESP) events is presented. When the energy of accelerated particles becomes very large, their back reaction on the flow can result in a shock that is significantly mediated, and as an example, we consider some results for the termination shock.

  15. San Antonio Vasopressin in Shock Symposium Report

    DTIC Science & Technology

    2010-01-01

    Keywords: Conference report Vasopressin Shock Cardiac arrest Traumatic brain injury Septic shock Haemorrhagic shock a b s t r a c t The...potential benefits of vasopressin use in shock. 2. Vasopressin deficiency states and shock While a vasopressin infusion has little vasopressor effect in...100pg/ml and restores arterial blood pressure by a direct vasopres- sor effect and by increasing sensitivity to pressor catecholamines. At low doses (1

  16. Management of Shock in Neonates.

    PubMed

    Bhat, B Vishnu; Plakkal, Nishad

    2015-10-01

    Shock is characterized by inadequate oxygen delivery to the tissues, and is more frequent in very low birth weight infants, especially in the first few days of life. Shock is an independent predictor of mortality, and the survivors are at a higher risk of neurologic impairment. Understanding the pathophysiology helps to recognize and classify shock in the early compensated phase and initiate appropriate treatment. Hypovolemia is rarely the primary cause of shock in neonates. Myocardial dysfunction is especially common in extremely preterm infants, and in term infants with perinatal asphyxia. Blood pressure measurements are easy, but correlate poorly with cerebral and systemic blood flows. Point-of-care cardiac ultrasound can help in individualized assessment of problems, selecting appropriate therapy and monitoring response, but may not always be available, and long-term benefits need to be demonstrated. The use of near-infrared spectroscopy to guide treatment of neonatal shock is currently experimental. In the absence of hypovolemia, excessive administration of fluid boluses is inappropriate therapy. Dobutamine and dopamine are the most common initial inotropes used in neonatal shock. Dobutamine has been shown to improve systemic blood flow, especially in very low birth weight infants, but dopamine is better at improving blood pressure in hypotensive infants. Newer inodilators including milrinone and levosimendan may be useful in selected settings. Data on long-term survival and neurologic outcomes following different management strategies are scarce and future research efforts should focus on this.

  17. Vascular Endothelium and Hypovolemic Shock.

    PubMed

    Gulati, Anil

    2016-01-01

    Endothelium is a site of metabolic activity and has a major reservoir of multipotent stem cells. It plays a vital role in the vascular physiological, pathophysiological and reparative processes. Endothelial functions are significantly altered following hypovolemic shock due to ischemia of the endothelial cells and by reperfusion due to resuscitation with fluids. Activation of endothelial cells leads to release of vasoactive substances (nitric oxide, endothelin, platelet activating factor, prostacyclin, mitochondrial N-formyl peptide), mediators of inflammation (tumor necrosis factor α, interleukins, interferons) and thrombosis. Endothelial cell apoptosis is induced following hypovolemic shock due to deprivation of oxygen required by endothelial cell mitochondria; this lack of oxygen initiates an increase in mitochondrial reactive oxygen species (ROS) and release of apoptogenic proteins. The glycocalyx structure of endothelium is compromised which causes an impairment of the protective endothelial barrier resulting in increased permeability and leakage of fluids in to the tissue causing edema. Growth factors such as angiopoetins and vascular endothelial growth factors also contribute towards pathophysiology of hypovolemic shock. Endothelium is extremely active with numerous functions, understanding these functions will provide novel targets to design therapeutic agents for the acute management of hypovolemic shock. Hypovolemic shock also occurs in conditions such as dengue shock syndrome and Ebola hemorrhagic fever, defining the role of endothelium in the pathophysiology of these conditions will provide greater insight regarding the functions of endothelial cells in vascular regulation.

  18. The evolution and cellular structure of a detonation subsequent to a head-on interaction with a shock wave

    SciTech Connect

    Botros, Barbara B.; Zhu, YuJian; Lee, John H.S.; Ng, Hoi Dick; Ju, Yiguang

    2007-12-15

    This paper analyzes the results of a head-on collision between a detonation and a planar shock wave. The evolution of the detonation cellular structure subsequent to the frontal collision was examined through smoked foil experiments. It is shown that a large reduction in cell size is observed following the frontal collision, and that the detonation cell widths are correlated well with the chemical kinetic calculations from the ZND model. From chemical kinetic calculations, the density increase caused by shock compression appears to be the main factor leading to the significant reduction in cell size. It was found that depending on the initial conditions, the transition to the final cellular pattern can be either smooth or spotty. This phenomenon appears to be equivalent to Oppenheim's strong and mild reflected shock ignition experiments. The difference between these two transitions is, however, more related to the stability of the incident detonation and the strength of the perturbation generated by the incident shock. (author)

  19. Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets

    NASA Technical Reports Server (NTRS)

    Fukuda, M. K.; Hingst, W. G.; Reshotko, E.

    1975-01-01

    An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary layer after a shock wave-boundary layer interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise.

  20. Refraction of cylindrical converging shock wave at an air/helium gaseous interface

    NASA Astrophysics Data System (ADS)

    Zhai, Zhigang; Li, Wei; Si, Ting; Luo, Xisheng; Yang, Jiming; Lu, Xiyun

    2017-01-01

    Refraction of a cylindrical converging shock wave at an inclined air/helium interface is investigated. Experimentally, based on the shock dynamics theory, a special wall profile is designed to generate a perfectly cylindrical converging shock wave. A soap film technique is developed to form an inclined discontinuous air/helium interface, and high-speed schlieren photography is adopted to capture the flow. Numerical simulations are also performed to compare with the experimental counterparts and to show details of refraction. In this work, two initial incident angles (45° and 60°) are considered. As the incident shock converges inward, the shock intensity increases while the incident angle decreases, causing possible transitions among the wave patterns. For the case of 45°, an irregular refraction of free precursor refraction (FPR) first occurs and gradually transits into regular refraction, while for the case of 60°, various irregular refractions of twin von Neumann refraction (TNR), twin regular refraction (TRR), free precursor von Neumann refraction (FNR), and FPR occur in sequence. The transition sequences do not belong to any groups described in the planar counterpart, indicating that the classification of the refraction phenomenon in the planar case is not exhaustive or cannot be applied to the converging case. It is also the first time to observe the transition from FNR to FPR, providing an experimental evidence for the previous numerical results. It is deemed that the difference between the velocities of the incident and transmitted shocks propagating along the interface is the primary factor that induces the transitions among wave patterns.

  1. A study of shock mitigating materials in a split Hopkinson bar configuration. Phase 1

    SciTech Connect

    Bateman, V.I.; Brown, F.A.; Hansen, N.R.

    1998-06-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125 fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical systems. As part of the investigation of packaging techniques, a two phase study of shock mitigating materials is being conducted. The purpose of the first phase reported here is to examine the performance of a joint that consists of shock mitigating material sandwiched in between steel and to compare the performance of the shock mitigating materials. A split Hopkinson bar experimental configuration simulates this joint and has been used to study the shock mitigating characteristics of seventeen, unconfined materials. The nominal input for these tests is an incident compressive wave with 50 fps peak (1,500 {micro}{var_epsilon} peak) amplitude and a 100 {micro}s duration (measured at 10% amplitude).

  2. Cosmic-ray acceleration during the impact of shocks on dense clouds

    NASA Technical Reports Server (NTRS)

    Jones, T. W.; Kang, Hyesung

    1993-01-01

    In order to elucidate the properties of diffusive shock acceleration in nonuniform environments, an extensive set of simulations of the dynamical interactions between plane nonradiative shocks and dense gas clouds was carried out initially in static equilibrium with their environments. These time-dependent calculations are based on the two-fluid model for diffusive cosmic ray transport, and include the dynamically active energetic proton component of the cosmic rays as well as passive electron and magnetic field components. Except when the incident shock is itself already dominated by cosmic ray pressure, it is found that the presence of the cloud adds little to the net acceleration efficiency of the original shock and can, in fact, reduce slightly the net amount of energy transferred to cosmic rays after a given time. It is found that, in 2D cloud simulations, the always-weak bow shock and the shock inside the cloud are less important to acceleration during the interaction than the tail shock.

  3. Simulations and experiments of ejecta generation in twice-shocked metals

    NASA Astrophysics Data System (ADS)

    Karkhanis, Varad; Ramaprabhu, Praveen; Buttler, William; Hammerberg, James; Cherne, Frank; Andrews, Malcolm

    2016-11-01

    Using continuum hydrodynamics embedded in the FLASH code, we model ejecta generation in recent target experiments, where a metallic surface was loaded by two successive shock waves. The experimental data were obtained from a two-shockwave, high-explosive tool at Los Alamos National Laboratory, capable of generating ejecta from a shocked tin surface in to a vacuum. In both simulations and experiment, linear growth is observed following the first shock event, while the second shock strikes a finite-amplitude interface leading to nonlinear growth. The timing of the second incident shock was varied systematically in our simulations to realize a finite-amplitude re-initialization of the RM instability driving the ejecta. We find the shape of the interface at the event of second shock is critical in determining the amount of ejecta, and thus must be used as an initial condition to evaluate subsequent ejected mass using a source model. In particular, the agreement between simulations, experiments and the mass model is improved when shape effects associated with the interface at second shock are incorporated. This work was supported in part by the (U.S.) Department of Energy (DOE) under Contract No. DE-AC52-06NA2-5396.

  4. Shock wave propagation in semi-crystalline polyethylene: An atomic-scale investigation

    NASA Astrophysics Data System (ADS)

    Elder, Robert M.; O'Connor, Thomas C.; Yeh, In-Chul; Chantawansri, Tanya L.; Sirk, Timothy W.; Robbins, Mark O.; Andzelm, Jan W.

    Highly oriented polyethylene (PE) fibers are used in protection applications, therefore elucidation of their response under high strain-rate impact events is vital. Although PE fibers can have high crystallinity (>95%), they also contain defects such as amorphous domains. Using molecular dynamics simulations, we investigate shock propagation through crystalline, amorphous, and semi-crystalline PE. We generate compressive shock waves of varying strength, quantify their dynamics, and characterize their effect on material properties at the atomic scale. In the semi-crystalline PE model, the differing density and molecular order of amorphous PE and crystalline PE result in differing shock impedances, which causes reflection and refraction of shock waves at interfaces between the phases. We quantify the properties (e.g. pressure, velocity) of the reflected and refracted waves, which differ from those of the incident wave, and compare with results from impedance matching. We also examine the reflection, absorption, and transmission of energy at the crystalline-amorphous interface. Depending on shock strength, amorphous defects can dissipate shock energy, which attenuates the shock and leads to effects such as localized heating.

  5. Steady shock wave reflections in nonequilibrium flows: thermodynamic stability and regular- to Mach-reflection transitions.

    NASA Astrophysics Data System (ADS)

    Grasso, Francesco; Paoli, Roberto

    1999-11-01

    Shock wave reflections in steady flows have been widely studied in the last decades for their importance in many aerospace applications, such as supersonic intakes and wind tunnel technologies. One of the yet unresolved problems is the understanding of the physical mechanism responsible for the transition between regular and Mach reflections and the hysteresis phenomenon (i.e. the attainement of different shock configurations for the same incident shock angle) as well as the stability of shock wave configurations. In the present paper we study the influence of thermochemical relaxation phenomena on shock reflections by means of a two-temperature model for the thermal nonequilibrium and the reduced Park's model for finite rate chemistry. Stable shock wave configurations are characterized by invoking Prigogine minimum entropy production principle. For that purpose we formulate the entropy budget for nonequilibrium flows and identify the different contributions to the evolution of entropy due to translational and vibrational heat conduction and species diffusion, as well as dissociation reactions and translational vibrational energy exchanges. A study of shock reflection transition is carried out at two Mach numbers (M=7.5 and M=9.8) both for air and nitrogen. In order to identify the controlling mechanisms that affect the transition and the hysteresis we also carry out simulations assuming an ideal gas behaviour.

  6. Mediation of the solar wind termination shock by non-thermal ions.

    PubMed

    Decker, R B; Krimigis, S M; Roelof, E C; Hill, M E; Armstrong, T P; Gloeckler, G; Hamilton, D C; Lanzerotti, L J

    2008-07-03

    Broad regions on both sides of the solar wind termination shock are populated by high intensities of non-thermal ions and electrons. The pre-shock particles in the solar wind have been measured by the spacecraft Voyager 1 (refs 1-5) and Voyager 2 (refs 3, 6). The post-shock particles in the heliosheath have also been measured by Voyager 1 (refs 3-5). It was not clear, however, what effect these particles might have on the physics of the shock transition until Voyager 2 crossed the shock on 31 August-1 September 2007 (refs 7-9). Unlike Voyager 1, Voyager 2 is making plasma measurements. Data from the plasma and magnetic field instruments on Voyager 2 indicate that non-thermal ion distributions probably have key roles in mediating dynamical processes at the termination shock and in the heliosheath. Here we report that intensities of low-energy ions measured by Voyager 2 produce non-thermal partial ion pressures in the heliosheath that are comparable to (or exceed) both the thermal plasma pressures and the scalar magnetic field pressures. We conclude that these ions are the >0.028 MeV portion of the non-thermal ion distribution that determines the termination shock structure and the acceleration of which extracts a large fraction of bulk-flow kinetic energy from the incident solar wind.

  7. Experimental studies of transpiration cooling with shock interaction in hypersonic flow, part B

    NASA Technical Reports Server (NTRS)

    Holden, Michael S.

    1994-01-01

    transpiration-cooled panels. The regions of shockwave/boundary layer interaction examined in these studies were induced by oblique shocks generated with a sharp, flat plate, inclined to the freestream at angles of 5 degrees, 7.5 degrees, and 10 degrees. It was found that, in the absence of an incident shock, transpiration cooling was a very effective method for reducing both the heat transfer and the skin friction loads on the surface. The helium coolant was found to be significantly more effective than nitrogen, because of its low molecular weight and high specific heat. The studies of shock-wave/transpiration-cooled surface interaction demonstrated that the interaction region between the incident shock and the low-momentum transpiration-cooled boundary layer did not result in a significant increase in the size of attached or separated interaction regions, and did not result in significant flowfield distortions above the interaction region. The increase in heating downstream of the shock-impingement point could easily be reduced to the values without shock impingement by a relatively small increase in the transpiration cooling in this region. Surprisingly, this increase in cooling rate did not result in a significant increase in size of the region ahead of the incident shock or create a significantly enlarged interaction region with a resultant increase in the distortion level in the inviscid flow. Thus, transpiration cooling appears to be a very effective technique to cool the internal surfaces of scramjet engines, where shocks in the engine would induce large local increases in wall heating and create viscous/inviscid interactions that could significantly disturb the smooth flow through the combustor. However, if hydrogen is used as the coolant, burning upstream of shock impingement might result in localized hot spots. Clearly, further research is needed in this area.

  8. Shock Interaction with Substrate in a Shock Induced Spray Process

    NASA Astrophysics Data System (ADS)

    Mrozinski, Kevin

    To further the knowledge of the Shock Induced Spray Process (SISP), an experimental apparatus which simulates Centerline's Waverider thermal spray gun was created which uses an unsteady flow to propel solid particles onto a substrate by the use of a shock wave to produce a coating. Experiments were conducted at a variety of operating supply pressures, firing frequencies, and stand off distances. A qualitative analysis was done using a custom Schlieren system along with a high speed camera. Insight into the flow behaviour in the SISP was established with the definition of six distinct phases. The formation of a bow shock, which is known to be detrimental to the SISP operation, is shown to be more prominent in the cases with higher supply pressure and close proximity of the apparatus exit to the substrate than with changes in firing frequency.

  9. Near anastigmatic grazing incidence telescope

    NASA Technical Reports Server (NTRS)

    Korsch, D.

    1984-01-01

    A performance capability assessment is presently conducted for short versus long grazing incidence telescope designs, in view of the observation that the field curvature and astigmatism that are the primary residual aberrations of a Wolter-type incidence telescope can be substantially reduced through mirror length reduction. A major advantage of the short element telescope is that, if sufficiently short, both the paraboloid and hyperboloid surfaces may be fabricated as a single piece; this significantly facilitates the task of alignment.

  10. Perioperative Hypothermia: Incidence and Prevention

    DTIC Science & Technology

    1990-01-01

    1990 Thesis/" Perioperative Hypothermia: Incidence and Prevention CRodney L. Fisher AFIT Student at: Columbia University AFIT/CI/CIA 90-120 AFT/I/I...Civilian Institution Programs DTIC CTELECTE 0 36 UNCLASSIFIFD 4 PERIOPERATIVE HYPOTHERMIA: INCIDENCE AND PREVENTION By Rodney L. Fisher, CAPT., USAF...Availability Codes Avall and/or Dit Special ABSTRACT Perioperative thermal regulation is discussed. A retrospective audit was conducted to identify the

  11. Incidence of Narcolepsy in Germany

    PubMed Central

    Oberle, Doris; Drechsel-Bäuerle, Ursula; Schmidtmann, Irene; Mayer, Geert; Keller-Stanislawski, Brigitte

    2015-01-01

    Study Objectives: Following the 2009 pandemic, reports of an association between an AS03 adjuvanted H1N1 pandemic influenza vaccine and narcolepsy were published. Besides determining background incidence rates for narcolepsy in Germany this study aimed at investigating whether there was a change in incidence rates of narcolepsy between the pre-pandemic, pandemic, and the post-pandemic period on the population level. Design: Retrospective epidemiological study on the incidence of narcolepsy with additional capture-recapture analysis. Setting: German sleep centers. Patients or Participants: Eligible were patients with an initial diagnosis of narcolepsy (ICD10 Code G47.4) within the period from January 1, 2007 to December 31, 2011. Interventions: None; observational study. Measurements and Results: A total of 342 sleep centers were invited to participate in the study. Adequate and suitable data were provided by 233 sleep centers (68.1%). A total of 1,198 patients with an initial diagnosis of narcolepsy within the observed period were included, of whom 106 (8.8%) were children and adolescents under the age of 18 years and 1,092 (91.2%) were adults. In children and adolescents, the age-standardized adjusted incidence rate significantly increased from 0.14/100,000 person-years in the pre-pandemic period to 0.50/100,000 person-years in the post-pandemic period (incidence density ratio, IDR 3.57; 95% CI 1.94–7.00). In adults, no significant change was detectable. This increase started in spring 2009. Conclusions: For the years 2007–2011, valid estimates for the incidence of narcolepsy in Germany were provided. In individuals under 18, the incidence rates continuously increased from spring 2009. Citation: Oberle D, Drechsel-Bäuerle U, Schmidtmann I, Mayer G, Keller-Stanislawski B. Incidence of narcolepsy in Germany. SLEEP 2015;38(10):1619–1628. PMID:25902804

  12. [Shock in obstetrics. Institutional experience].

    PubMed

    Bonfante Ramírez, E; Ahued Ahued, R; García-Benítez, C Q; Bolaños Ancona, R; Callejos, T; Juárez García, L

    1997-04-01

    Shock is one of the most difficult problems an obstetrician can face. Hemorrhage is the main reason of shock. A descriptive and retrospective research was conducted at Instituto Nacional de Perinatología, from January 1992 to May 1996, including all patients admitted to the intensive care unit with diagnosis of shock. There were found 90 cases with diagnosis of shock, 82 were hipovolemic, and 8 cases had the septic kind of shock. The average of age was 32.2 years, with a gestational age between 6.2 to 41.4 weeks . There were 71 healthy patients, hypertension was associated to pregnancy in 9 cases, infertility in two, myomatosis in 2, and diabetes in 2 more patients. Other 5 cases reported different pathologies. The most frequent cause for hipovolemic shock resulted to be placenta acreta (40 cases), followed by uterine tone alterations in 37 patients, ectopic pregnancy in 7, uterine rupture or perforation in 4, and vaginal or cervical lacerations in 2. The estimated blood loss varied from 2200 cc to 6500 cc, and the minimal arterial pressure registered during shock was between 40/20 mmHg to 90/60 mmHg. Medical initial assistance consisted in volume reposition with crystalloids, globular packages, and plasma expansors in 73 patients (81.1%). The rest of the patients received in addition coloids, platelets and cryoprecipitates. A total of 76 patients required surgical intervention consisting in total abdominal hysterectomy. In 5 cases the previous surgical procedure was done and ligation of hypogastric vessels was needed. Salpingectomy was performed in 5 patients, and rupture or perforation repair in 3. The average surgery time was 2 hours and 33 minutes. The observed complications were 7 cases with abscess of the cupula, consumption coagulopathy in 2, 1 vesical quirurgical injury, 1 intestinal occlusion, and 11 vesico-vaginal fistula. The average days of hospitalization resulted to be 5. The most frequent kind of shock seen by obstetricians is the hipovolemic type

  13. Shock tube study of the reaction H plus O2 plus Ar yields HO2 plus Ar

    NASA Technical Reports Server (NTRS)

    Jachimowski, C. J.; Houghton, W. M.

    1972-01-01

    Rate coefficient data for the recombination reaction H + 02 + Ar yields H02 + Ar have been determined from studies of lean hydrogen-oxygen mixtures behind incident shock waves over the temperature range of 948 to 1125 K. Hydroxyl radical concentration profiles were measured by ultraviolet absorption spectroscopy, and rate data were obtained through analysis of induction time and exponential growth parameter data. Analysis of the data yielded a rate coefficient which was generally lower than most of the more recent values obtained from shock tube studies. The effect of boundary layer formation on the conditions behind the shock was also examined and found to be negligible.

  14. Vibration and shock test report for the H1616-1 container and the Savannah River Hydride Transport Vessel

    SciTech Connect

    York, A.R. II; Joseph, B.J.

    1992-11-01

    Sandia National Laboratories performed random vibration and shock tests on a tritium hydride transport vessel that was packaged in an H1616-1 container. The objective of the tests was to determine if the hydride transport vessel remains leaktight under vibration and shock normally incident to transport, which is a requirement that the hydride transport vessel must meet to be shipped in the H1616-1. Helium leak tests before and after the vibration and shock tests showed that the hydride transport vessel remained leaktight under the specified conditions. There were no detrimental effects on the containment vessel of the H1616-1.

  15. Temperature measurements behind reflected shock waves in air. [radiometric measurement of gas temperature in self-absorbing gas flow

    NASA Technical Reports Server (NTRS)

    Bader, J. B.; Nerem, R. M.; Dann, J. B.; Culp, M. A.

    1972-01-01

    A radiometric method for the measurement of gas temperature in self-absorbing gases has been applied in the study of shock tube generated flows. This method involves making two absolute intensity measurements at identical wavelengths, but for two different pathlengths in the same gas sample. Experimental results are presented for reflected shock waves in air at conditions corresponding to incident shock velocities from 7 to 10 km/s and an initial driven tube pressure of 1 torr. These results indicate that, with this technique, temperature measurements with an accuracy of + or - 5 percent can be carried out. The results also suggest certain facility related problems.

  16. Transient shocks beyond the heliopause

    DOE PAGES

    Fermo, R. L.; Pogorelov, N. V.; Burlaga, L. F.

    2015-09-30

    The heliopause is a rich, dynamic surface affected by the time-dependent solar wind. Stream interactions due to coronal mass ejections (CMEs), corotating interaction regions (CIRs), and other transient phenomena are known to merge producing global merged interaction regions (GMIRs). Numerical simulations of the solar wind interaction with the local interstellar medium (LISM) show that GMIRs, as well other time-dependent structures in the solar wind, may produce compression/rarefaction waves and shocks in the LISM behind the heliopause. These shocks may initiate wave activity observed by the Voyager spacecraft. The magnetometer onboard Voyager 1 indeed observed a few structures that may bemore » interpreted as shocks. We present numerical simulations of such shocks in the year of 2000, when both Voyager spacecraft were in the supersonic solar wind region, and in 2012, when Voyager 1 observed traveling shocks. In the former case, Voyager observations themselves provide time- dependent boundary conditions in the solar wind. In the latter case, we use OMNI data at 1 AU to analyze the plasma and magnetic field behavior after Voyager 1 crossed the heliospheric boundary. Numerical results are compared with spacecraft observations.« less

  17. Transient shocks beyond the heliopause

    SciTech Connect

    Fermo, R. L.; Pogorelov, N. V.; Burlaga, L. F.

    2015-09-30

    The heliopause is a rich, dynamic surface affected by the time-dependent solar wind. Stream interactions due to coronal mass ejections (CMEs), corotating interaction regions (CIRs), and other transient phenomena are known to merge producing global merged interaction regions (GMIRs). Numerical simulations of the solar wind interaction with the local interstellar medium (LISM) show that GMIRs, as well other time-dependent structures in the solar wind, may produce compression/rarefaction waves and shocks in the LISM behind the heliopause. These shocks may initiate wave activity observed by the Voyager spacecraft. The magnetometer onboard Voyager 1 indeed observed a few structures that may be interpreted as shocks. We present numerical simulations of such shocks in the year of 2000, when both Voyager spacecraft were in the supersonic solar wind region, and in 2012, when Voyager 1 observed traveling shocks. In the former case, Voyager observations themselves provide time- dependent boundary conditions in the solar wind. In the latter case, we use OMNI data at 1 AU to analyze the plasma and magnetic field behavior after Voyager 1 crossed the heliospheric boundary. Numerical results are compared with spacecraft observations.

  18. [Shock: concepts for a definition].

    PubMed

    Poderoso, J J; Carreras, M C; Lisdero, C; Schöpfer, F; Riobó, N; Peralta, J

    1998-01-01

    The shock syndrome has been classically considered as a consequence of both decreased tissue perfusion and O2 supply; however, in some types of shock like septic or traumatic ones, regional blood flows may be increased. A decade ago, mitochondrial alterations consistent with uncoupling of oxidative phosphorylation were reported in either endotoxemic or hemorrhagic experimental shock or in humans. Recently, the discovery of nitric oxide (NO) and its increase in the shock state, has opened new perspectives in the understanding of this problem. Nitric oxide produces vasodilatation and, at the same time, increases the mitochondrial production of O2 active species like superoxide anion. Both radicals react to form a strong oxidant that is able to nitrate the phenolic rings of proteins: peroxynitrite. This effect leads to the impairment of the activities of different mitochondrial enzymes like succinate dehydrogenase and ATPase and the mitochondrial function and finally, to decreased energy levels and to multiorgan failure. The increase in NO release is due to the effects of circulating peptides and of increased adhesion of neutrophils to the endothelium and to the positive effects of inflammatory mediators like TNF-alpha and cytokines on inducible NOS (iNOS) expression in endothelium and tissues. It is suggested that the shock state is the consequence of an imbalance between NO and O2 and their metabolites.

  19. Diagnostic of shock wave processes

    NASA Astrophysics Data System (ADS)

    Urtiew, P. A.

    1992-05-01

    Experimental measurements of high rate processes taking place in a shock wave dynamic environment require that the diagnostic systems have fast response and high resolution. This is not a trivial requirement considering the fact that under shock loading one can expect not only sudden changes of state across the shock discontinuity but also subsequent changes in pressure, temperature and volume due to chemical reaction, phase change and other transformations which may also take place behind the shock wave. Among the various parameters which provide direct ties to theoretical studies of the equation of state and at the same time yield to relatively accurate experimental measurements are shock velocity, particle velocity and pressure. Described here are the optical techniques VISAR and Fabry Perot interferometer for observing particle and free surface velocities in transparent media as well as in situ foil gauges for measuring pressure and particle velocity within the sample. Although these techniques are not new they have been continuously improved and upgraded at our facility to yield greater accuracy, reliability and state of the art performance. The emphasis in this paper is on the operational features of the measuring techniques, but examples of experimental results are also included.

  20. Shock wave-droplet interaction

    NASA Astrophysics Data System (ADS)

    Habibi Khoshmehr, Hamed; Krechetnikov, Rouslan

    2016-11-01

    Disintegration of a liquid droplet under the action of a shock wave is experimentally investigated. The shock wave-pulse is electromagnetically generated by discharging a high voltage capacitor into a flat spiral coil, above which an isolated circular metal membrane is placed in a close proximity. The Lorentz force arising due to the eddy current induced in the membrane abruptly accelerates it away from the spiral coil thus generating a shock wave. The liquid droplet placed at the center of the membrane, where the maximum deflection occurs, is disintegrated in the process of interaction with the shock wave. The effects of droplet viscosity and surface tension on the droplet destruction are studied with high-speed photography. Water-glycerol solution at different concentrations is used for investigating the effect of viscosity and various concentrations of water-sugar and water-ethanol solution are used for studying the effect of surface tension. Here we report on how the metamorphoses, which a liquid drop undergoes in the process of interaction with a shock wave, are affected by varied viscosity and surface tension.

  1. Polarized radiation from inhomogeneous shocks

    SciTech Connect

    Wu, Kinwah.

    1989-01-01

    Strongly polarized radiation from AM Herculis binaries is believed to be due to cyclotron emission from hot magnetized plasmas. The flat optically thin spectra and strong IR polarization observed in these binaries cannot be explained by models assuming a homogeneous emission region with a simple geometry. Therefore, the cyclotron emission from infinite plasma cylinders with uniform magnetic fields and temperatures was studied, but with a variety of axially symmetric electron density profiles and it was shown that such inhomogeneous plasmas are able to produce relatively flat spectra which cannot be produced by the homogeneous models. The polarization at low frequencies is shown to be stronger than that due to the homogeneous plasmas and the polarization at high frequencies is weaker. The steady state hydrodynamics was also studied of bremsstrahlung dominated shocks and the cyclotron emission was calculated from them. Three types of accretion rate profiles (uniform, axisymmetric and asymmetric) were considered. The shock-structure is planar for the uniform accretion rate case. The shock due to an axisymmetric accretion rate is a curved surface. For asymmetric accretion, the post-shock region is asymmetric and hence produces asymmetric light curves. All these inhomogeneous shocks produce flat optical/IR spectra and strong IR polarization.

  2. Electron heating at interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.; Zwickl, R. D.

    1982-01-01

    Data for 41 forward interplanetary shocks show that the ratio of downstream to upstream electron temperatures, T/sub e/(d/u) is variable in the range between 1.0 (isothermal) and 3.0. On average, (T/sub e/(d/u) = 1.5 with a standard deviation, sigma e = 0.5. This ratio is less than the average ratio of proton temperatures across the same shocks, (T/sub p/(d/u)) = 3.3 with sigma p = 2.5 as well as the average ratio of electron temperatures across the Earth's bow shock. Individual samples of T/sub e/(d/u) and T/sub p/(d/u) appear to be weakly correlated with the number density ratio. However the amounts of electron and proton heating are well correlated with each other as well as with the bulk velocity difference across each shock. The stronger shocks appear to heat the protons relatively more efficiently than they heat the electrons.

  3. Cyber Incidents Involving Control Systems

    SciTech Connect

    Robert J. Turk

    2005-10-01

    The Analysis Function of the US-CERT Control Systems Security Center (CSSC) at the Idaho National Laboratory (INL) has prepared this report to document cyber security incidents for use by the CSSC. The description and analysis of incidents reported herein support three CSSC tasks: establishing a business case; increasing security awareness and private and corporate participation related to enhanced cyber security of control systems; and providing informational material to support model development and prioritize activities for CSSC. The stated mission of CSSC is to reduce vulnerability of critical infrastructure to cyber attack on control systems. As stated in the Incident Management Tool Requirements (August 2005) ''Vulnerability reduction is promoted by risk analysis that tracks actual risk, emphasizes high risk, determines risk reduction as a function of countermeasures, tracks increase of risk due to external influence, and measures success of the vulnerability reduction program''. Process control and Supervisory Control and Data Acquisition (SCADA) systems, with their reliance on proprietary networks and hardware, have long been considered immune to the network attacks that have wreaked so much havoc on corporate information systems. New research indicates this confidence is misplaced--the move to open standards such as Ethernet, Transmission Control Protocol/Internet Protocol, and Web technologies is allowing hackers to take advantage of the control industry's unawareness. Much of the available information about cyber incidents represents a characterization as opposed to an analysis of events. The lack of good analyses reflects an overall weakness in reporting requirements as well as the fact that to date there have been very few serious cyber attacks on control systems. Most companies prefer not to share cyber attack incident data because of potential financial repercussions. Uniform reporting requirements will do much to make this information available to

  4. Energetic ion acceleration at collisionless shocks

    NASA Technical Reports Server (NTRS)

    Decker, R. B.; Vlahos, L.

    1985-01-01

    An example is presented from a test particle simulation designed to study ion acceleration at oblique turbulent shocks. For conditions appropriate at interplanetary shocks near 1 AU, it is found that a shock with theta sub B n = 60 deg is capable of producing an energy spectrum extending from 10 keV to approx. 1 MeV in approx 1 hour. In this case total energy gains result primarily from several separate episodes of shock drift acceleration, each of which occurs when particles are scattered back to the shock by magnetic fluctuations in the shock vicinity.

  5. Shock compression of simulated adobe

    NASA Astrophysics Data System (ADS)

    Braithwaite, C. H.; Church, P. D.; Gould, P. J.; Stewart, B.; Jardine, A. P.

    2017-01-01

    A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us =2.26up+0.37) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement.

  6. Entropy shaping by shock decay

    NASA Astrophysics Data System (ADS)

    Piriz, A. R.; Sun, Y. B.; Tahir, N. A.

    2016-11-01

    A previous model [Piriz et al., Phys. Plasmas 23, 032704 (2016)] developed for describing the evolution of a shock wave driven by an arbitrary pressure pulse, is shown to be suitable for calculating the entropy shaping induced by a shock of decaying intensity. It is also shown that by allowing a causal connection between the shock and the piston, the model results to be complementary to the well-known self-similar solution for the impulsive loading problem, which is valid in the asymptotic regime when both fronts become decoupled. As a consequence, the entropy distribution depends on the details of the driving pressure pulse. A comparison with the available numerical simulations is presented.

  7. Plasma Stratification by Planar Shocks

    NASA Astrophysics Data System (ADS)

    Keenan, Brett; Simakov, Andrei; Taitano, William; Chacon, Luis; Daughton, William

    2016-10-01

    A number of experimental observables in neutron yield and capsule compression in Inertial Confinement Fusion (ICF) experiments have been evading explanation by standard, single-fluid, hydrodynamic (hydro) numerical simulations. Fuel stratification - resulting from particle diffusion, multi-ion temperature separation (in the case of OMEGA experiments with gas filled capsules), and certain kinetic effects - is a likely culprit. As a preliminary step to elucidate these effects, we consider mass fraction and temperature stratification by shocks in plasmas with two ion species. We present an analytical solution valid for very weak shocks (M - 1 << 1). Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, we describe the stratification for shocks with arbitrary mach number, and we rigorously delineate the kinetic and hydrodynamic regimes in terms of Mach number, relative species concentration, and ion species mass ratio - thereby clarifying the conditions under which significant departure from single-fluid hydrodynamics may occur.

  8. Shock compression of liquid hydrazine

    SciTech Connect

    Garcia, B.O.; Chavez, D.J.

    1995-01-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used by the Air Force and NASA for aerospace propulsion and power systems. Because the propellant modules that contain the hydrazine can be subject to debris impacts during their use, the shock states that can occur in the hydrazine need to be characterized to safely predict its response. Several shock compression experiments have been conducted in an attempt to investigate the detonability of liquid hydrazine; however, the experiments results disagree. Therefore, in this study, we reproduced each experiment numerically to evaluate in detail the shock wave profiles generated in the liquid hydrazine. This paper presents the results of each numerical simulation and compares the results to those obtained in experiment. We also present the methodology of our approach, which includes chemical kinetic experiments, chemical equilibrium calculations, and characterization of the equation of state of liquid hydrazine.

  9. True rise in anaphylaxis incidence

    PubMed Central

    Yang, Min-Suk; Kim, Ju-Young; Kim, Byung-Keun; Park, Heung-Woo; Cho, Sang-Heon; Min, Kyung-Up; Kang, Hye-Ryun

    2017-01-01

    Abstract The incidence trend of anaphylaxis in Asia is not well investigated. The aim of this study is to estimate the entire population-based incidence of anaphylaxis in Korea using a nationwide administrative database. Data over a 7-year period (2008–2014) was obtained from the Korean National Health Insurance (NHI) claims database which covers 97.9% of the entire Korean population. Using diagnosis codes from the International Classification of Diseases-10 for anaphylaxis (T78.0, T78.2, T80.5, and T88.6), we identified the annual number of patients who had visited any hospital with a primary diagnosis of anaphylaxis. Incidence rates were calculated using the population distribution data of all NHI beneficiaries. The incidence of anaphylaxis in Korea was 32.19 episodes per 100,000 person-years in 2014, which nearly doubled from 2008 (16.02 episodes per 100,000 person-years). The incidence of anaphylaxis increased continuously throughout these years regardless of gender and age groups (P for trend < 0.001). Female was significantly less predisposed than male (adjusted odds ratio [OR], 0.69; 95% confident interval [CI], 0.66–0.72; P < 0.001). The incidence was the lowest in 0 to 19 age group and the highest in 40 to 69 age group (adjusted OR, 2.41; 95% CI, 2.29–2.54; P < 0.001). In conclusion, we report the increasing time trend of anaphylaxis incidence rates using nationwide claims database for the first time in Asia. PMID:28151851

  10. Shock Initiation of Damaged Explosives

    SciTech Connect

    Chidester, S K; Vandersall, K S; Tarver, C M

    2009-10-22

    Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

  11. Shock modelling of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Cuesta, L.; Phillips, J. P.; Mampaso, A.

    1994-06-01

    The kinematics of Planetary Nebulae are analyzed in terms of the solutions to the equations of hydrodynamic equilibrium developed by J. Canto. We apply our analysis to the Planetary Nebulae NGC 6905 and NGC 6537. A detailed spectroscopic study of these objects reveals the existence of high nuclear velocities, together with complex kinematic structures and unusual emission line intensities. Shock ionization clearly plays a key role in these nebulae. Remarkably good agreement is obtained when comparing the synthetic maps and spectra resulting from the shock solutions with the observational data.

  12. Shock compaction of molybdenum powder

    NASA Technical Reports Server (NTRS)

    Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

    1983-01-01

    Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

  13. Method of making shock cells

    SciTech Connect

    Leblanc, R. F.; Cummins, W. T.

    1984-10-16

    A method of making an energy-absorbing shock cell for mounting bumper devices on legs of offshore oil rig structures having inner and outer metal tubes connected by an intervening vulcanized rubber sleeve maintained under compression adhesively bonded to the inner and outer metal tubes. The shock cell is made by a series of operations in which portions of the metal tubes are coated with adhesive material, and the rubber sleeve is bonded to the adhesive coated areas by vulcanization and post-vulcanized heating.

  14. Generation of Quasi-Perpendicular Collisionless Shocks by a Laser-Driven Magnetic Piston

    NASA Astrophysics Data System (ADS)

    Schaeffer, Derek

    Collisionless shocks are ubiquitous in many space and astrophysical plasmas. However, since space shocks are largely steady-state, spacecraft are not well suited to studying shock formation in situ. This work is concerned with the generation and study in a laboratory setting of magnetized, quasi-perpendicular collisionless shocks relevant to space shocks. Experiments performed at the Large Plasma Device (LAPD) at UCLA and the Trident Laser Facility at Los Alamos National Laboratory (LANL) combined a magnetic piston driven by a high-energy laser (Raptor at UCLA or Trident at LANL) incident on a carbon target with a preformed, magnetized background plasma. Magnetic flux measurements and 2D hybrid simulations indicate that a magnetosonic pulse consistent with a low-Mach number collisionless shock was formed in the ambient plasma. The characteristics of the shock are analyzed and compared to other experiments in which no shock or a shock precursor formed. The results and simulations reveal that the various experimental conditions can be organized into weak and moderate coupling regimes, in which no shock forms, and a strong coupling regime, in which a full shock forms. A framework for studying these regimes and designing future shock experiments is devised. Early-time laser-plasma parameters necessary to characterize the different shock coupling regimes are studied through experiments performed at the LAPD and Phoenix laboratory at UCLA. In addition to spectroscopic and fast-gate filtered photography, the experiments utilize a custom Thomson scattering diagnostic, optimized for a novel electron density and temperature regime where the transition from collective to non-collective scattering could be spatially resolved. Data from the experiments and 3D analytic modeling indicate that the laser-plasma is best fit at early times with an isentropic, adiabatic fluid model and is consistent with a recombination-dominated plasma for which the electron temperature Te∝ t -1

  15. Weak-shock theory for spherical shock waves

    SciTech Connect

    Curtis, W.D.; Rosenkilde, C.E.; Yee, K.S.

    1982-03-01

    We develop weak shock theory in a form which would allow us to utilize output from a hydrodynamic code (e.g. KOVEC) as either an initial or boundary condition and then follow the wave evolution to much greater distances than the codes themselves can attain.

  16. Shock absorber operates over wide range

    NASA Technical Reports Server (NTRS)

    Creasy, W. K.; Jones, J. C.

    1965-01-01

    Piston-type hydraulic shock absorber, with a metered damping system, operates over a wide range of kinetic energy loading rates. It is used for absorbing shock and vibration on mounted machinery and heavy earth-moving equipment.

  17. Shock State of Itokawa Regolith Grains

    NASA Technical Reports Server (NTRS)

    Zolensky, M.; Nishiizumi, K.; Mikouchi, T.; Chan, Q. H. S.; Martinez, J.; Caffee, M.

    2014-01-01

    One of the fundamental aspects of any astromaterial is its shock history, since this factor elucidates critical historical events, and also because shock metamorphism can alter primary mineralogical and petrographic features, and reset chronologies.

  18. Factors Affecting Shock Sensitivity of Energeticv Materials

    NASA Astrophysics Data System (ADS)

    Chakravarty, Avic; Gifford, Michael John; Greenaway, Martin; Proud, William; Field, John

    2001-06-01

    An extensive study has been carried out into the relationships between the particle size of a charge, the density to which it is packed, the presence of inert additives and the sensitivity of the charge to different initiating shocks. The critical parameters for three different shock regimes have been found. The long duration shocks are provided by a commercial detonator, the medium duration shocks are provided by an electrically driven flyer-plate and the short duration shocks are imparted using laser-driven flyer plates. It has been shown that the order of sensitivity of charges to different shock regimes varies. In particular, ultrafine materials have been shown to relatively insensitive to long duration low pressure shocks and sensitive to short duration high pressure shocks. The materials that have been studied include HNS, RDX and PETN.

  19. Kinetic Simulations of Particle Acceleration at Shocks

    SciTech Connect

    Caprioli, Damiano; Guo, Fan

    2015-07-16

    Collisionless shocks are mediated by collective electromagnetic interactions and are sources of non-thermal particles and emission. The full particle-in-cell approach and a hybrid approach are sketched, simulations of collisionless shocks are shown using a multicolor presentation. Results for SN 1006, a case involving ion acceleration and B field amplification where the shock is parallel, are shown. Electron acceleration takes place in planetary bow shocks and galaxy clusters. It is concluded that acceleration at shocks can be efficient: >15%; CRs amplify B field via streaming instability; ion DSA is efficient at parallel, strong shocks; ions are injected via reflection and shock drift acceleration; and electron DSA is efficient at oblique shocks.

  20. Fresh look at floating shock fitting

    NASA Technical Reports Server (NTRS)

    Hartwich, PETER-M.

    1990-01-01

    A fast implicit upwind procedure for the two-dimensional Euler equations is described that allows accurate computations of shocked flows on nonadapted meshes. Away from shocks, the second-order accurate upwinding is based on the split-coefficient-matrix (SCM) method. In the presence of shocks, the difference stencils are modified using a floating shock fitting technique. Rapid convergence to steady-state solutions is attained with a diagonalized approximate factorization (AF) algorithm. Results are presented for Riemann's problem, for a regular shock reflection at an inviscid wall, for supersonic flow past a cylinder, and for a transonic airfoil. All computed shocks are ideally sharp and in excellent agreement with other numerical results or 'exact' solutions. Most importantly, this has been accomplished on unusually crude meshes without any attempt to align grid lines with shock fronts or to cluster grid lines around shocks.

  1. Converging cylindrical shocks in ideal magnetohydrodynamics

    SciTech Connect

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  2. Converging cylindrical shocks in ideal magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{μ _0/p_0} I/(2 π ) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  3. Methamphetamine Lab Incidents, 2004-2014

    MedlinePlus

    ... Liderazgo de la DEA Resource Center » Statistics & Facts » Methamphetamine Lab Incidents Methamphetamine Lab Incidents, 2004-2014 NOTE: These maps include all meth incidents, including labs, "dumpsites" or "chemical and glassware" ...

  4. Suppressive and Facilitative Effects of Shock Intensity and Interresponse Times Followed by Shock

    ERIC Educational Resources Information Center

    Everly, Jessica B.; Perone, Michael

    2012-01-01

    Although response-dependent shock often suppresses responding, response facilitation can occur. In two experiments, we examined the suppressive and facilitative effects of shock by manipulating shock intensity and the interresponse times that produced shock. Rats' lever presses were reinforced on a variable-interval 40-s schedule of food…

  5. Entropy jump across an inviscid shock wave

    NASA Technical Reports Server (NTRS)

    Salas, Manuel D.; Iollo, Angelo

    1995-01-01

    The shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure are shown to be the same, however density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.

  6. Shock, Post-Shock Annealing, and Post-Annealing Shock in Ureilites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    2006-01-01

    The thermal and shock histories of ureilites can be divided into four periods: 1) formation, 2) initial shock, 3) post-shock annealing, and 4) post-annealing shock. Period 1 occurred approx.4.55 Ga ago when ureilites formed by melting chondritic material. Impact events during period 2 caused silicate darkening, undulose to mosaic extinction in olivines, and the formation of diamond, lonsdaleite, and chaoite from indigenous carbonaceous material. Alkali-rich fine-grained silicates may have been introduced by impact injection into ureilites during this period. About 57% of the ureilites were unchanged after period 2. During period 3 events, impact-induced annealing caused previously mosaicized olivine grains to become aggregates of small unstrained crystals. Some ureilites experienced reduction as FeO at the edges of olivine grains reacted with C from the matrix. Annealing may also be responsible for coarsening of graphite in a few ureilites, forming euhedral-appearing, idioblastic crystals. Orthopyroxene in Meteorite Hills (MET) 78008 may have formed from pigeonite by annealing during this period. The Rb-Sr internal isochron age of approx.4.0 Ga for MET 78008 probably dates the annealing event. At this late date, impacts are the only viable heat source. About 36% of ureilites experienced period 3 events, but remained unchanged afterwards. During period 4, approx.7% of the ureilites were shocked again, as is evident in the polymict breccia, Elephant Moraine (EET) 83309. This rock contains annealed mosaicized olivine aggregates composed of small individual olivine crystals that exhibit undulose extinction. Ureilites may have formed by impact-melting chondritic material on a primitive body with heterogeneous O isotopes. Plagioclase was preferentially lost from the system due to its low impedance to shock compression. Brief melting and rapid burial minimized the escape of planetary-type noble gases from the ureilitic melts. Incomplete separation of metal from silicates

  7. Thin Foil Acceleration Method for Measuring the Unloading Isentropes of Shock-Compressed Matter

    SciTech Connect

    Asay, J.R.; Chhabildas, L.C.; Fortov, V.E.; Kanel, G.I.; Khishchenko, K.V.; Lomonosov, I.V.; Mehlhorn, T.; Razorenov, S.V.; Utkin, A.V.

    1999-07-21

    This work has been performed as part of the search for possible ways to utilize the capabilities of laser and particle beams techniques in shock wave and equation of state physics. The peculiarity of these techniques is that we have to deal with micron-thick targets and not well reproducible incident shock wave parameters, so all measurements should be of a high resolution and be done in one shot. Besides the Hugoniots, the experimental basis for creating the equations of state includes isentropes corresponding to unloading of shock-compressed matter. Experimental isentrope data are most important in the region of vaporization. With guns or explosive facilities, the unloading isentrope is recovered from a series of experiments where the shock wave parameters in plates of standard low-impedance materials placed behind the sample are measured [1,2]. The specific internal energy and specific volume are calculated from the measured p(u) release curve which corresponds to the Riemann integral. This way is not quite suitable for experiments with beam techniques where the incident shock waves are not well reproducible. The thick foil method [3] provides a few experimental points on the isentrope in one shot. When a higher shock impedance foil is placed on the surface of the material studied, the release phase occurs by steps, whose durations correspond to that for the shock wave to go back and forth in the foil. The velocity during the different steps, connected with the knowledge of the Hugoniot of the foil, allows us to determine a few points on the isentropic unloading curve. However, the method becomes insensitive when the low pressure range of vaporization is reached in the course of the unloading. The isentrope in this region can be measured by recording the smooth acceleration of a thin witness plate foil. With the mass of the foil known, measurements of the foil acceleration will give us the vapor pressure.

  8. Stability of shocks relating to the shock ignition inertial fusion energy scheme

    SciTech Connect

    Davie, C. J. Bush, I. A.; Evans, R. G.

    2014-08-15

    Motivated by the shock ignition approach to improve the performance of inertial fusion targets, we make a series of studies of the stability of shock waves in planar and converging geometries. We examine stability of shocks moving through distorted material and driving shocks with non-uniform pressure profiles. We then apply a fully 3D perturbation, following this spherically converging shock through collapse to a distorted plane, bounce and reflection into an outgoing perturbed, broadly spherical shock wave. We find broad shock stability even under quite extreme perturbation.

  9. Experimental investigation of Richtmyer-Meshkov instability before and after the reflected shock compression

    NASA Astrophysics Data System (ADS)

    Jourdan, G.; Houas, L.

    1996-06-01

    Results of an experimental investigation on the Richtmyer-Meshkov instability of a He-CO2 interface are reported. A simultaneous three-directional laser absorption technique is used to follow, at a single abscissa, the evolution of the created mixing zone before and after the interaction with the reflected shock, during the same run. CO2 density profiles have been determined within both the incident and the compressed mixing zones. However, near the pure CO2, the wall boundary layer reflected shock interaction perturbs measurements and does not allow objective conclusions.

  10. First-principles calculation of the reflectance of shock-compressed xenon

    SciTech Connect

    Norman, G. E.; Saitov, I. M. Stegailov, V. V.

    2015-05-15

    Within electron density functional theory (DFT), the reflectance of radiation from shock-compressed xenon plasma is calculated. The dependence of the reflectance on the frequency of the incident radiation and on the plasma density is considered. The Fresnel formula is used. The expression for the longitudinal dielectric tensor in the long-wavelength limit is used to calculate the imaginary part of the dielectric function (DF). The real part of the DF is determined by the Kramers-Kronig transformation. The results are compared with experimental data. An approach is proposed to estimate the plasma frequency in shock-compressed xenon.

  11. A Study of Fundamental Shock Noise Mechanisms

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.

    1997-01-01

    This paper investigates two mechanisms fundamental to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. This numerical approach is validated by comparison with results obtained by linear theory for a small-disturbance case. Analysis of the perturbation energy with Myers' energy corollary demonstrates that acoustic energy is generated by the interaction of acoustic disturbances with shocks. This analysis suggests that shock motion generates acoustic and entropy disturbance energy. Shock deformation is modeled numerically by examining the interaction of a vortex ring with a shock. These numerical simulations demonstrate the generation of both an acoustic wave and contact surfaces. The acoustic wave spreads cylindrically. The sound intensity is highly directional and the sound pressure increases with increasing shock strength. The numerically determined relationship between the sound pressure and the Mach number is found to be consistent with experimental observations of shock noise. This consistency implies that a dominant physical process in the generation of shock noise is modeled in this study.

  12. Understanding hypovolaemic, cardiogenic and septic shock.

    PubMed

    Garretson, Sharon; Malberti, Shelly

    Shock is a complex physiological syndrome. If it is not detected and treated promptly, it can lead to death. This article reviews and summarises the latest findings, treatment and nursing and medical interventions for three of the most common forms of shock, namely, hypovolaemic, cardiogenic and septic shock.

  13. Shock absorbing mount for electrical components

    NASA Technical Reports Server (NTRS)

    Dillon, R. F., Jr.; Mayne, R. C. (Inventor)

    1975-01-01

    A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided.

  14. 33 CFR 159.105 - Shock test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Shock test. 159.105 Section 159... MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with liquid... shocks that are ten times the force of gravity (10g) and have a duration of 20-25 milliseconds...

  15. Shock characterization of Diallyl Phthalate (DAP)

    SciTech Connect

    Weirick, L.J.

    1992-09-01

    This study involved the shock characterization of Diallyl Phthalate (DAP), in particular, the equation of state as measured by the shock Hugoniot. Tests were done between 1 and 11 GPa impact shock pressure. The Hugoniot parameters were determined to be: [rho][sub 0]= 1.743, C[sub 0] = 2.20, and S = 2.33.

  16. Heat shock in the springtime.

    PubMed

    Morano, Kevin A; Sistonen, Lea; Mezger, Valérie

    2014-11-01

    A collaborative workshop dedicated to the discussion of heat shock factors in stress response, development, and disease was held on April 22-24, 2014 at the Université Paris Diderot in Paris, France. Recent years have witnessed an explosion of interest in these highly conserved transcription factors, with biological roles ranging from environmental sensing to human development and cancer.

  17. Shock treatment of corn stover.

    PubMed

    Bond, Austin; Rughoonundun, Hema; Petersen, Eric; Holtzapple, Carol; Holtzapple, Mark

    2017-01-27

    Corn stover digestibility was enhanced via shock treatment. A slurry of lime-treated corn stover was placed in a partially filled closed vessel. From the ullage space, either a shotgun shell was fired into the slurry, or a gas mixture was detonated. Various conditions were tested (i.e., pressures, depth, solids concentrations, gas mixtures). A high pressurization rate (108,000 MPa/s shotgun shells; 4,160,000 MPa/s hydrogen/oxygen detonation) was the only parameter that improved enzymatic digestibility. Stoichiometric propane/air deflagration had a low pressurization rate (37.2 MPa/s) and did not enhance enzymatic digestibility. Without shock, enzymatic conversion of lime-treated corn stover was 0.80 g glucan digested/g glucan fed with an enzyme loading of 46.7 mg protein/g glucan. With shock, the enzyme loading was reduced by ∼2× while maintaining the same conversion. Detonations are extraordinarily fast; rapidly cycling three small vessels (0.575 m(3) each) every 7.5 s enables commercially relevant shock treatment (2,000 tone/day). © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 2017.

  18. Cardiovascular failure and cardiogenic shock.

    PubMed

    Patel, Ankitkumar K; Hollenberg, Steven M

    2011-10-01

    Cardiovascular system failure is commonly faced by the intensivist. Heart failure can occur due to a host of predisposing cardiac disorders or as secondary effects of systemic illness. When the heart is unable to provide an adequate cardiac output to maintain adequate tissue perfusion, cardiogenic shock ensues. Without prompt diagnosis and appropriate management, these patients have significant morbidity and mortality, with in-hospital mortality approaching 60% for all age groups. Accurate and rapid identification of cardiogenic shock as a medical emergency, with expeditious implementation of appropriate therapy, can lead to improved clinical outcomes. In this review, we discuss optimal strategies for diagnosis and monitoring of cardiogenic shock. We discuss the diverse therapeutic strategies employed for cardiogenic shock, including pharmacological (e.g., vasoactive agents, fibrinolytic agents), mechanical (e.g., intraaortic balloon pumps, left ventricular assist devices, percutaneous coronary intervention [PCI]), and surgical approaches such as coronary artery bypass graft (CABG), valvular repair or replacement (e.g., for acute mitral regurgitation, ventricular septal rupture, or free wall rupture).

  19. Shock desensitizing of solid explosive

    SciTech Connect

    Davis, William C

    2010-01-01

    Solid explosive can be desensitized by a shock wave too weak to initiate it promptly, and desensitized explosive does not react although its chemical composition is almost unchanged. A strong second shock does not cause reaction until it overtakes the first shock. The first shock, if it is strong enough, accelerates very slowly at first, and then more rapidly as detonation approaches. These facts suggest that there are two competing reactions. One is the usual explosive goes to products with the release of energy, and the other is explosive goes to dead explosive with no chemical change and no energy release. The first reaction rate is very sensitive to the local state, and the second is only weakly so. At low pressure very little energy is released and the change to dead explosive dominates. At high pressure, quite the other way, most of the explosive goes to products. Numerous experiments in both the initiation and the full detonation regimes are discussed and compared in testing these ideas.

  20. History of shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Delius, Michael

    2000-07-01

    The first reports on the fragmentation of human calculi with ultrasound appeared in the fifties. Initial positive results with an extracorporeal approach with continuous wave ultrasound could, however, not be reproduced. A more promising result was found by generating the acoustic energy either in pulsed or continuous form directly at the stone surface. The method was applied clinically with success. Extracorporeal shock-wave generators unite the principle of using single ultrasonic pulses with the principle of generating the acoustic energy outside the body and focusing it through the skin and body wall onto the stone. Häusler and Kiefer reported the first successful contact-free kidney stone destruction by shock waves. They had put the stone in a water filled cylinder and generated a shock wave with a high speed water drop which was fired onto the water surface. To apply the new principle in medicine, both Häusler and Hoff's group at Dornier company constructed different shock wave generators for the stone destruction; the former used a torus-shaped reflector around an explosion wire, the latter the electrode-ellipsoid system. The former required open surgery to access the kidney stone, the latter did not. It was introduced into clinical practice after a series of experiments in Munich.

  1. 2-Shock layered tuning campaign

    NASA Astrophysics Data System (ADS)

    Masse, Laurent; Dittrich, T.; Khan, S.; Kyrala, G.; Ma, T.; MacLaren, S.; Ralph, J.; Salmonson, J.; Tipton, R.; Los Alamos Natl Lab Team; Lawrence Livermore Natl Lab Team

    2016-10-01

    The 2-Shock platform has been developed to maintain shell sphericity throughout the compression phase of an indirect-drive target implosion and produce a stagnating hot spot in a quasi 1D-like manner. A sub-scale, 1700 _m outer diameter, and thick, 200 _m, uniformly Silicon doped, gas-filled plastic capsule is driven inside a nominal size 5750 _m diameter ignition hohlraum. The hohlraum fill is near vacuum to reduce back-scatter and improve laser/drive coupling. A two-shock pulse of about 1 MJ of laser energy drives the capsule. The thick capsule prevents ablation front feed-through to the imploded core. This platform has demonstrated its efficiency to tune a predictable and reproducible 1-D implosion with a nearly round shape. It has been shown that the high foot performance was dominated by the local defect growth due to the ablation front instability and by the hohlraum radiation asymmetries. The idea here is to take advantage of this 2-Shock platform to design a 1D-like layered implosion and eliminates the deleterious effects of radiation asymmetries and ablation front instability growth. We present the design work and our first experimental results of this near one-dimensional 2-Shock layered design. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  2. Shock Propagation In Crustal Rock

    DTIC Science & Technology

    1991-04-29

    Fritz, and W. J. Crater, The equation of state of solids from shock wave studies, in High-Velocity Impact Phenomena, edited by R. Kinslow , pp. 249-419...Boiling AFB Washington, DC 20332-6448 Mr. Alfred Lieberman Dr. Frank F. Pilotte ACDA/VI-OA’State Department Bldg HQ AFTAC/IT Room 5726 Patrick AFB, FL

  3. Shock characterization of TOAD pins

    SciTech Connect

    Weirick, L.J.; Navarro, N.J.

    1995-08-01

    The purpose of this program was to characterize Time Of Arrival Detectors (TOAD) pins response to shock loading with respect to risetime, amplitude, repeatability and consistency. TOAD pins were subjected to impacts of 35 to 420 kilobars amplitude and approximately 1 ms pulse width to investigate the timing spread of four pins and the voltage output profile of the individual pins. Sets of pins were also aged at 45{degrees}, 60{degrees}, and 80{degrees}C for approximately nine weeks before shock testing at 315 kilobars impact stress. Four sets of pins were heated to 50.2{degrees}C (125{degrees}F) for approximately two hours and then impacted at either 50 or 315 kilobars. Also, four sets of pins were aged at 60{degrees}C for nine weeks and then heated to 50.2{degrees}C before shock testing at 50 and 315 kilobars impact stress, respectively. Particle velocity measurements at the contact point between the stainless steel targets and TOAD pins were made using a Velocity Interferometer System for Any Reflector (VISAR) to monitor both the amplitude and profile of the shock waves.

  4. Shock characterization of toad pins

    SciTech Connect

    Weirick, L.J.; Navarro, M.J.

    1996-05-01

    The purpose of this program was to characterize Time Of Arrival Detectors (TOAD) pins response to shock loading with respect to risetime, amplitude, repeatability and consistency. TOAD pins were subjected to impacts of 35 to 420 kilobars amplitude and approximately 1 ms pulse width to investigate the timing spread of four pins and the voltage output profile of the individual pins. Sets of pins were also aged at 45{degree}, 60{degree} and 80{degree}C for approximately nine weeks before shock testing at 315 kilobars impact stress. Four sets of pins were heated to 50.2{degree}C (125{degree}F) for approximately two hours and then impacted at either 50 or 315 kilobars. Also, four sets of pins were aged at 60{degree}C for nine weeks and then heated to 50.2{degree}C before shock testing at 50 and 315 kilobars impact stress, respectively. Particle velocity measurements at the contact point between the stainless steel targets and TOAD pins were made using a Velocity Interferometer System for Any Reflector (VISAR) to monitor both the amplitude and profile of the shock waves. {copyright} {ital 1996 American Institute of Physics.}

  5. The shocking truth about meniscus.

    PubMed

    Andrews, Stephen; Shrive, Nigel; Ronsky, Janet

    2011-11-10

    The menisci of the knee are structures integral to the long term health of the knee joint. The primary function of these tissues is to distribute load across the tibiofemoral joint by increasing the congruency of the joint, thereby decreasing the resultant stress experienced by the articular cartilages. The menisci also play a secondary role in stabilizing the joint, particularly in the anterior cruciate ligament deficient knee, and also have roles in joint lubrication and proprioception. Also, an oft-cited role of this tissue is that of a shock absorber. We will review the literature supporting this shock absorption paradigm and describe the limitations and errors in the conclusions made by these studies. Consequently, we will show that the literature is inconclusive with no support for the shock absorption paradigm, which should therefore not be stated as a function of the menisci. We will describe how one of the three articles in support of this paradigm actually could be interpreted to the contrary and support the idea that the menisci may play no significant role in shock absorption at the knee at all, with the two remaining papers being inconclusive.

  6. Supersonic jet shock noise reduction

    NASA Technical Reports Server (NTRS)

    Stone, J. R.

    1984-01-01

    Shock-cell noise is identified to be a potentially significant problem for advanced supersonic aircraft at takeoff. Therefore NASA conducted fundamental studies of the phenomena involved and model-scale experiments aimed at developing means of noise reduction. The results of a series of studies conducted to determine means by which supersonic jet shock noise can be reduced to acceptable levels for advanced supersonic cruise aircraft are reviewed. Theoretical studies were conducted on the shock associated noise of supersonic jets from convergent-divergent (C-D) nozzles. Laboratory studies were conducted on the influence of narrowband shock screech on broadband noise and on means of screech reduction. The usefulness of C-D nozzle passages was investigated at model scale for single-stream and dual-stream nozzles. The effect of off-design pressure ratio was determined under static and simulated flight conditions for jet temperatures up to 960 K. Annular and coannular flow passages with center plugs and multi-element suppressor nozzles were evaluated, and the effect of plug tip geometry was established. In addition to the far-field acoustic data, mean and turbulent velocity distributions were measured with a laser velocimeter, and shadowgraph images of the flow field were obtained.

  7. MEMS reliability in shock environments

    SciTech Connect

    TANNER,DANELLE M.; WALRAVEN,JEREMY A.; HELGESEN,KAREN SUE; IRWIN,LLOYD W.; BROWN,FREDERICK A.; SMITH,NORMAN F.; MASTERS,NATHAN

    2000-02-09

    In order to determine the susceptibility of the MEMS (MicroElectroMechanical Systems) devices to shock, tests were performed using haversine shock pulses with widths of 1 to 0.2 ms in the range from 500g to 40,000g. The authors chose a surface-micromachined microengine because it has all the components needed for evaluation: springs that flex, gears that are anchored, and clamps and spring stops to maintain alignment. The microengines, which were unpowered for the tests, performed quite well at most shock levels with a majority functioning after the impact. Debris from the die edges moved at levels greater than 4,000g causing shorts in the actuators and posing reliability concerns. The coupling agent used to prevent stiction in the MEMS release weakened the die-attach bond, which produced failures at 10,000g and above. At 20,000g the authors began to observe structural damage in some of the thin flexures and 2.5-micron diameter pin joints. The authors observed electrical failures caused by the movement of debris. Additionally, they observed a new failure mode where stationary comb fingers contact the ground plane resulting in electrical shorts. These new failure were observed in the control group indicating that they were not shock related.

  8. Economic Shocks, Wealth, and Welfare

    ERIC Educational Resources Information Center

    Frankenberg, Elizabeth; Smith, James P.; Thomas, Duncan

    2003-01-01

    The immediate effects of the Asian crisis on the well-being of Indonesians are examined using the Indonesia Family Life Survey, an ongoing longitudinal household survey. There is tremendous diversity in the effect of the shock: for some households, it was devastating; for others it brought new opportunities. A wide array of mechanisms was adopted…

  9. EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

    NASA Technical Reports Server (NTRS)

    Glass, C. E.

    1994-01-01

    New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow

  10. INTERPLANETARY SHOCKS LACKING TYPE II RADIO BURSTS

    SciTech Connect

    Gopalswamy, N.; Kaiser, M. L.; Xie, H.; Maekelae, P.; Akiyama, S.; Yashiro, S.; Howard, R. A.; Bougeret, J.-L.

    2010-02-20

    We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks ({approx}34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed {approx}535 km s{sup -1}) and only {approx}40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km s{sup -1} and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration {approx}+6.8 m s{sup -2}), while those associated with RL shocks were decelerating (average acceleration {approx}-3.5 m s{sup -2}). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter-hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is predominant

  11. Interplanetary Shocks Lacking Type 2 Radio Bursts

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Xie, H.; Maekela, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L.

    2010-01-01

    We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks (approximately 34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed approximately 535 km/s) and only approximately 40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km/s and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration approximately +6.8 m/s (exp 2)), while those associated with RL shocks were decelerating (average acceleration approximately 3.5 m/s (exp 2)). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter-hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is

  12. In vitro comparison of shock wave lithotripsy machines

    NASA Astrophysics Data System (ADS)

    Teichman, Joel M.; Cecconi, Patricia P.; Pearle, Margaret S.; Clayman, Ralph V.

    2005-04-01

    We tested the hypothesis that shock wave lithotripsy machines vary in the ability to fragment stones to small size. Calcium oxalate monohydrate, calcium phosphate, cystine and struvite calculi were fragmented in vitro with the Dornier HM3, Storz Modulith SLX, Siemens Lithostar C, Medstone STS-T, HealthTronics LithoTron 160, Dornier Doli S and Medispec Econolith lithotriptors. Stones were given 2000 shocks or the FDA limit. Post-lithotripsy fragment size was compared. Struvite calculi were completely fragmented by all devices. The mean incidence of calcium phosphate dihydrate, calcium oxalate monohydrate, and cystine stones rendered into fragments greater than 2 mm was 0% for the HM3, Modulith SLX and Lithostar C, 10% for the STS-T, 3% for the LithoTron 160, 29% for the Doli and 18% for the Econolith (p=0.04); 0% for the HM3, Modulith SLX, Lithostar C, STS-T and LithoTron 160, 4% for the Doli and 9% for the Econolith (p=0.15); 1% for the HM3, 0% for the Modulith SLX, 1% for the Lithostar C, 10% for the STS-T, 14% for the LithoTron 160, 3% for the Doli and 9% for the Econolith (p=0.44), respectively. Shock wave lithotriptors vary in fragmentation ability.

  13. Permeability enhancement by shock cooling

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  14. Symmetry of spherically converging shock waves through reflection, relating to the shock ignition fusion energy scheme.

    PubMed

    Davie, C J; Evans, R G

    2013-05-03

    We examine the properties of perturbed spherically imploding shock waves in an ideal fluid through the collapse, bounce, and development into an outgoing shock wave. We find broad conservation of the size and shape of ingoing and outgoing perturbations when viewed at the same radius. The outgoing shock recovers the velocity of the unperturbed shock outside the strongly distorted core. The results are presented in the context of the robustness of the shock ignition approach to inertial fusion energy.

  15. The microphysics of collisionless shock waves.

    PubMed

    Marcowith, A; Bret, A; Bykov, A; Dieckman, M E; Drury, L O'C; Lembège, B; Lemoine, M; Morlino, G; Murphy, G; Pelletier, G; Plotnikov, I; Reville, B; Riquelme, M; Sironi, L; Novo, A Stockem

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

  16. Incidents Unsuitable for Moral Education.

    ERIC Educational Resources Information Center

    Thomas, R. Murray; And Others

    Educators from over 30 countries judged the suitability of incidents in moral education in the context of their native environment. Participants were 54 secondary school principals or teachers, most of whom were graduate students or married to graduate students at the University of California, Santa Barbara. They were given descriptions of 23…

  17. Laboratory simulations of supernova shockwaves: Formation of a second shock ahead of a radiative shock

    SciTech Connect

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

    2005-09-28

    Supernovae launch spherical shocks into the circumstellar medium (CSM). These shocks may interact with both the intergalactic magnetic field (IGM) and local mass accumulations (possibly with their own local magnetic fields). The latter interaction may trigger star formation. The shocks have high Mach numbers and may be radiative. We have created similar shocks in the laboratory by focusing laser pulses onto the tip of a solid pin surrounded by ambient gas; ablated material from the pin rapidly expands and launches a shock through the surrounding gas. The shock may then be allowed to interact with (a) mass accumulations, (b) magnetic fields, or (c) allowed to expand freely. We will present examples of each type of experiment, but mainly discuss a new phenomena observed first in (c); at the edge of the radiatively heated gas ahead of the shock, a second shock forms. The two expanding shocks are simultaneously visible for a time, until the original shock stalls from running into the heated gas. The second shock remains visible and continues to expand. A minimum condition for the formation of the second shock is that the original shock is super-critical, i.e., the temperature distribution ahead of the original shock has an inflexion point. In a non-radiative control experiment the second shock does not form.

  18. Laboratory simulations of supernova shockwaves: Formation of a second shock ahead of a radiative shock

    SciTech Connect

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

    2005-01-28

    Supernovae launch spherical shocks into the circumstellar medium (CSM). These shocks may interact with both the intergalactic magnetic field (IGM) and local mass accumulations (possibly with their own local magnetic fields). The latter interaction may trigger star formation. The shocks have high Mach numbers and may be radiative. We have created similar shocks in the laboratory by focusing laser pulses onto the tip of a solid pin surrounded by ambient gas; ablated material from the pin rapidly expands and launches a shock through the surrounding gas. The shock may then be allowed to interact with (a) mass accumulations, (b) magnetic fields, or (c) allowed to expand freely. We will present examples of each type of experiment, but mainly discuss a new phenomena observed first in (c); at the edge of the radiatively heated gas ahead of the shock, a second shock forms. The two expanding shocks are simultaneously visible for a time, until the original shock stalls from running into the heated gas. The second shock remains visible and continues to expand. A minimum condition for the formation of the second shock is that the original shock is super-critical, i.e., the temperature distribution ahead of the original shock has an inflexion point. In a non-radiative control experiment the second shock does not form.

  19. Calorimetric thermobarometry of experimentally shocked quartz

    NASA Technical Reports Server (NTRS)

    Ocker, Katherine D.; Gooding, James L.; Hoerz, Friedrich

    1994-01-01

    Structural damage in experimentally shock-metamorphosed, granular quartz is quantitatively measurable by differential scanning calorimetry (DSC). Shock-induced loss of crystallinity is witnessed by disappearance of the alpha/beta phase transformation and evolution of a broad endoenthalpic strain peak at 650-900 K. The strain-energy peak grows rapidly at less than 10 GPa but declines with increasing shock pressure; it approaches zero at 32 GPa where vitrification is extensive. Effects of grain size and post-shock thermal history must be better understood before calorimetric thermobarometry of naturally shocked samples becomes possible.

  20. On the simulation of ballistic shock loads

    NASA Technical Reports Server (NTRS)

    Hollburg, Uwe

    1987-01-01

    Blast or penetrator-impact induced shocks are characterized by high acceleration levels, particularily in the higher frequency range and for a short time duration. These shocks are dangerous for the equipment of ships, combat vehicles, airplanes or spacecraft structures. As ballistic shock loads are insufficiently simulated by laboratory test machines, researchers designed a ballistic shock simulator. The impact induced shocks are simulated by an explosive and the vehicle to be bombarded is replaced by a simplified structure. This structure is suitable to accommodate any equipment which can be tested up to their load limits.

  1. Streptococcus agalactiae Toxic Shock-Like Syndrome

    PubMed Central

    Al Akhrass, Fadi; Abdallah, Lina; Berger, Steven; Hanna, Rami; Reynolds, Nina; Thompson, Shellie; Hallit, Rabih; Schlievert, Patrick M.

    2013-01-01

    Abstract We present 2 patients with Streptococcus agalactiae toxic shock-like syndrome and review another 11 well-reported cases from the literature. Streptococcal toxic shock-like syndrome is a devastating illness with a high mortality rate, therefore we stress the importance of early supportive management, antimicrobial therapy, and surgical intervention. Toxic shock-like syndrome is likely to be underestimated in patients with invasive Streptococcus agalactiae infection who present with shock. Early diagnosis requires high suspicion of the illness, along with a thorough mucocutaneous examination. Streptococcus agalactiae produces uncharacterized pyrogenic toxins, which explains the ability of the organism to cause toxic shock-like syndrome. PMID:23263717

  2. The plasma physics of shock acceleration

    NASA Technical Reports Server (NTRS)

    Jones, Frank C.; Ellison, Donald C.

    1991-01-01

    The history and theory of shock acceleration is reviewed, paying particular attention to theories of parallel shocks which include the backreaction of accelerated particles on the shock structure. The work that computer simulations, both plasma and Monte Carlo, are playing in revealing how thermal ions interact with shocks and how particle acceleration appears to be an inevitable and necessary part of the basic plasma physics that governs collisionless shocks is discussed. Some of the outstanding problems that still confront theorists and observers in this field are described.

  3. A new facility for studying shock-wave passage over dust layers

    NASA Astrophysics Data System (ADS)

    Chowdhury, A. Y.; Marks, B. D.; Johnston, H. Greg; Mannan, M. Sam; Petersen, E. L.

    2016-03-01

    Dust explosion hazards in areas where coal and other flammable materials are found have caused unnecessary loss of life and halted business operations in some instances. The elimination of secondary dust explosion hazards, i.e., reducing dust dispersion, can be characterized in shock tubes to understand shock-dust interactions. For this reason, a new shock-tube test section was developed and integrated into an existing shock-tube facility. The test section has large windows to allow for the use of the shadowgraph technique to track dust-layer growth behind a passing normal shock wave, and it is designed to handle an initial pressure of 1 atm with an incident shock wave Mach number as high as 2 to mimic real-world conditions. The test section features an easily removable dust pan with inserts to allow for adjustment of the dust-layer thickness. The design also allows for changing the experimental variables such as initial pressure, shock Mach number (Ms), dust-layer thickness, and the characteristics of the dust itself. The characterization experiments presented herein demonstrate the advantages of the authors' test techniques toward providing new physical insights over a wider range of data than what have been available heretofore in the literature. Limestone dust with a layer thickness of 3.2 mm was subjected to Ms = 1.23, 1.32, and 1.6 shock waves, and dust-layer rise height was mapped with respect to time after shock passage. Dust particles subjected to a Ms = 1.6 shock wave rose more rapidly and to a greater height with respect to shock wave propagation than particles subjected to Ms = 1.23 and 1.32 shock waves. Although these results are in general agreement with the literature, the new data also highlight physical trends for dust-layer growth that have not been recorded previously, to the best of the authors' knowledge. For example, the dust-layer height rises linearly until a certain time where the growth rate is dramatically reduced, and in this second

  4. Aberrations for Grazing Incidence Optics

    NASA Technical Reports Server (NTRS)

    Saha, Timo T.

    2008-01-01

    Large number of grazing incidence telescope configurations have been designed and studied. Wolte1 telescopes are commonly used in astronomical applications. Wolter telescopes consist of a paraboloidal primary mirror and a hyperboloidal or an ellipsoidal secondary mirror. There are 8 possible combinations of Wolter telescopes. Out of these possible designs only type 1 and type 2 telescopes are widely used. Type 1 telescope is typically used for x-ray applications and type 2 telescopes are used for EUV applications. Wolter-Schwarzshild (WS) telescopes offer improved image quality over a small field of view. The WS designs are stigmatic and free of third order coma and, therefore, the PSF is significantly better over a small field of view. Typically the image is more symmetric about its centroid. As for the Wolter telescopes there are 8 possible combinations of WS telescopes. These designs have not been widely used because the surface equations are complex parametric equations complicating the analysis and typically the resolution requirements are too low to take full advantage of the WS designs. There are several other design options. Most notable are wide field x-ray telescope designs. Polynomial designs were originally suggested by Burrows4 and hyperboloid-hyperboloid designs for solar physics applications were designed by Harvey5. No general aberration theory exists for grazing incidence telescopes that would cover all the design options. Several authors have studied the aberrations of grazing incidence telescopes. A comprehensive theory of Wolter type 1 and 2 telescopes has been developed. Later this theory was expanded to include all possible combinations of grazing incidence and also normal incidence paraboloid-hyperboloid and paraboloid-ellipsoid telescopes. In this article the aberration theory of Wolter type telescopes is briefly reviewed.

  5. INCIDENT REPORTING: LEARNING FROM EXPERIENCE

    SciTech Connect

    Weiner, Steven C.; Kinzey, Bruce R.; Dean, Jesse D.; Davis, Patrick B.; Ruiz, Antonio

    2007-09-12

    Experience makes a superior teacher. Sharing the details surrounding safety events is one of the best ways to help prevent their recurrence elsewhere. This approach requires an open, non-punitive environment to achieve broad benefits. The Hydrogen Incident Reporting Tool (www.h2incidents.org) is intended to facilitate the sharing of lessons learned and other relevant information gained from actual experiences using and working with hydrogen and hydrogen systems. Its intended audience includes those involved in virtually any aspect of hydrogen technology, systems and use, with an emphasis towards energy and transportation applications. The database contains records of safety events both publicly available and/or voluntarily submitted. Typical records contain a general description of the occurrence, contributing factors, equipment involved, and some detailing of consequences and changes that have been subsequently implemented to prevent recurrence of similar events in the future. The voluntary and confidential nature and other characteristics surrounding the database mean that any analysis of apparent trends in its contents cannot be considered statistically valid for a universal population. A large portion of reported incidents have occurred in a laboratory setting due to the typical background of the reporting projects, for example. Yet some interesting trends are becoming apparent even at this early stage of the database’s existence and general lessons can already be taken away from these experiences. This paper discusses the database and a few trends that have already become apparent for the reported incidents. Anticipated future uses of this information are also described. This paper is intended to encourage wider participation and usage of the incidents reporting database and to promote the safety benefits offered by its contents.

  6. 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.

  7. Shock-induced chemistry in organic materials

    SciTech Connect

    Dattelbaum, Dana M; Sheffield, Steve; Engelke, Ray; Manner, Virginia; Chellappa, Raja; Yoo, Choong - Shik

    2011-01-20

    The combined 'extreme' environments of high pressure, temperature, and strain rates, encountered under shock loading, offer enormous potential for the discovery of new paradigms in chemical reactivity not possible under more benign conditions. All organic materials are expected to react under these conditions, yet we currently understand very little about the first bond-breaking steps behind the shock front, such as in the shock initiation of explosives, or shock-induced reactivity of other relevant materials. Here, I will present recent experimental results of shock-induced chemistry in a variety of organic materials under sustained shock conditions. A comparison between the reactivity of different structures is given, and a perspective on the kinetics of reaction completion under shock drives.

  8. Bow shock and magnetosheath waves at Mercury

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Behannon, K. W.

    1975-01-01

    Mariner 10 measurements at the Mercury bow shock provide examples where the magnetic field is approximately parallel or perpendicular to the bow shock normal. Upstream of a broad irregular parallel shock, left hand circularly polarized waves are observed which cut off very sharply at approximately 4 Hz. Upstream of a perpendicular shock, right hand circularly polarized waves are observed which persist up to the Nyquist frequency of 12 Ha. Determination of the wave propagation vector as a function of frequency helps conclusively identify the waves as whistler mode waves propagating from the shock. The magnetosheath downstream of the parallel shock is disturbed more than that downstream of the perpendicular shock particularly below 1 Hz. In the latter case regular left hand polarized waves observed slightly above the proton gyrofrequency are identified as ion cyclotron waves with wavelength approximately 300 km which are Doppler shifted up to their observed frequency.

  9. Shock Wave Dynamics in Weakly Ionized Plasmas

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  10. Kinetic simulaitons of astrophysical collisionless shocks (Invited)

    NASA Astrophysics Data System (ADS)

    Spitkovsky, A.

    2009-12-01

    Nonthermal emission from a variety of astrophysical sources, including relativistic jets and supernova remnants, is often attributed to collisionless shocks. These shocks are inferred to accelerate particles and in some cases strongly amplify magnetic fields. How this happens remains to be clarified through both theory and observations. In this talk, I will present a summary of recent progress in kinetic modeling of collisionless shocks using particle-in-cell simulations. I will discuss the internal structure of relativistic and non-relativistic shocks, concentrating on the conditions necessary for particle acceleration. Large-scale shock simulations show ab-initio Fermi acceleration of particles from the thermal pool to power-law distributions and can set constraints on the shock acceleration efficiency and geometry. Other results that will be discussed include the amplification of magnetic fields by accelerated particles through streaming instabilities, and the electron-ion temperature equilibration in collisionless shocks.

  11. Factors Affecting Shock Sensitivity of Energetic Materials

    NASA Astrophysics Data System (ADS)

    Chakravarty, A.; Gifford, M. J.; Greenaway, M. W.; Proud, W. G.; Field, J. E.

    2002-07-01

    An extensive study has been carried out into the relationships between the particle size of a charge, the density to which it is packed, the presence of inert additives and the sensitivity of the charge to different initiating shocks. The critical parameters for two different shock regimes have been found. The long duration shocks are provided by a commercial detonator and the short duration shocks are imparted using laser-driven flyer plates. It has been shown that the order of sensitivity of charges to different shock regimes varies. In particular, ultrafine materials have been shown to be relatively insensitive to long duration low pressure shocks and sensitive to short duration high pressure shocks. The materials that have been studied include HNS, RDX and PETN.

  12. Optical carrier wave shocking: detection and dispersion.

    PubMed

    Kinsler, P; Radnor, S B P; Tyrrell, J C A; New, G H C

    2007-06-01

    Carrier wave shocking is studied using the pseudospectral spatial-domain (PSSD) technique. We describe the shock detection diagnostics necessary for this numerical study and verify them against theoretical shocking predictions for the dispersionless case. These predictions show a carrier envelope phase and pulse bandwidth sensitivity in the single-cycle regime. The flexible dispersion management offered by the PSSD enables us to independently control the linear and nonlinear dispersion. Customized dispersion profiles allow us to analyze the development of both carrier self-steepening and shocks. The results exhibit a marked asymmetry between normal and anomalous dispersion, both in the limits of the shocking regime and in the (near) shocked pulse wave forms. Combining these insights, we offer some suggestions on how carrier shocking (or at least extreme self-steepening) might be realized experimentally.

  13. SUPPRESSIVE AND FACILITATIVE EFFECTS OF SHOCK INTENSITY AND INTERRESPONSE TIMES FOLLOWED BY SHOCK

    PubMed Central

    Everly, Jessica B.; Perone, Michael

    2012-01-01

    Although response-dependent shock often suppresses responding, response facilitation can occur. In two experiments, we examined the suppressive and facilitative effects of shock by manipulating shock intensity and the interresponse times that produced shock. Rats' lever presses were reinforced on a variable-interval 40-s schedule of food presentation. Shock followed either long or short interresponse times. Shock intensity was raised from 0.05 mA to 0.4 mA or 0.8 mA. Overall, shock contingent on long interresponse times punished long interresponse times and increased response rates. Shock contingent on short interresponse times punished short interresponse times and decreased response rates. In Experiment 1, raising the range of interresponse times that produced shock enhanced these effects. In Experiment 2, the effects of shock intensity depended on the interresponse times that produced shock. When long interresponse times produced shock, low intensities increased response rates. High intensities decreased response rates. When short interresponse times produced shock, high shock intensities punished short interresponse times and decreased response rates more than low intensities. The results may explain why punishment procedures occasionally facilitate responding and establish parameters for future studies of punishment. PMID:23144508

  14. Water impact shock test system

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The basic objective was to design, manufacture, and install a shock test system which, in part, would have the ability to subject test articles weighing up to 1,000 pounds to both half sine and/or full sine pulses having peak levels of up to 50 G's with half sine pulse durations of 100 milliseconds or full sine period duration of 200 milliseconds. The tolerances associated with the aforementioned pulses were +20% and -10% for the peak levels and plus or minus 10% for the pulse durations. The subject shock test system was to be capable of accepting test article sizes of up to 4 feet by 4 feet mounting surface by 4 feet in length.

  15. Anaphylactic shock: mechanisms and treatment.

    PubMed Central

    Brown, A F

    1995-01-01

    This paper reviews the mechanisms of anaphylactic shock in terms of the immunoglobulin and non-immunoglobulin triggering events, and the cellular events based on the rise in intracellular cyclic AMP and calcium that release preformed granule-associated mediators and the rapidly formed, newly synthesized mediators predominantly based on arachidonic acid metabolism. These primary mediators recruit other cells with the release of secondary mediators that either potentiate or ultimately curtail the anaphylactic reaction. The roles of these mediators in the various causes of cardiovascular collapse are examined. The treatment of anaphylactic shock involves oxygen, adrenaline and fluids. The importance and safety of intravenous adrenaline are discussed. Combined H1 and H2 blocking antihistamines and steroids have a limited role. Glucagon and other adrenergic drugs are occasionally used, and several new experimental drugs are being developed. PMID:7582425

  16. Shock sensing dual mode warhead

    SciTech Connect

    Shamblen, M.; Walchak, M.T.; Richmond, L.

    1980-12-31

    A shock sensing dual mode warhead is provided for use against both soft and hard targets and is capable of sensing which type of target has been struck. The warhead comprises a casing made of a ductile material containing an explosive charge and a fuze assembly. The ductile warhead casing will mushroom upon striking a hard target while still confining the explosive. Proper ductility and confinement are necessary for fuze shock sensing. The fuze assembly contains a pair of parallel firing trains, one initiated only by dynamic pressure caused high impact deceleration and one initiated by low impact deceleration. The firing train actuated by high impact deceleration senses dynamic pressure transmitted, during deformation of the warhead, through the explosive filler which is employed as a fuzing signature. The firing train actuated by low impact deceleration contains a pyrotechnic delay to allow penetration of soft targets.

  17. State Methods for a Cyber Incident

    DTIC Science & Technology

    2012-03-01

    Statewide Emergency Response and Response Plan SIPC State Infrastructure Protection Center SIRT Security Incident Response Team SIRT State Incident...by statute and policy to report agency information security incidents to the state Security Incident Response Team ( SIRT ). Those reports are made...through recent state statutes. P-16 Yes, agencies are required by statute and policy to report information security incidents to the SIRT . Q-17

  18. Shock tube measurements of specific reaction rates in the branched chain CH4-CO-O2 system

    NASA Technical Reports Server (NTRS)

    Brabbs, T. A.; Brokaw, R. S.

    1974-01-01

    Rate constants of two elementary bimolecular reactions involved in the oxidation of methane have been determined by monitoring the exponential growth of CO flame band emission behind incident shocks in three suitably chosen gas mixtures. The data do not support a mechanism which invokes the four center process CH3 + O2 yields CH2O + OH for the reaction of methyl with oxygen.

  19. Table and Charts of Equilibrium Normal-shock Properties for Pure Hydrogen with Velocities to 70 km/sec. Revised.

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Wilder, S. E.

    1976-01-01

    Errors found in the original edition are corrected. Refinement was made in procedures for solving the conservation relations for an incident (moving), standing, and reflected normal shock, as well as in computational methods for determining thermochemical-equilibrium hydrogen properties. A six-species hydrogen model replaces the original four-species model, and the heat of formation and spectroscopic constants used in this six-species model are listed in appendix A. In appendix B, comparisons are made between a number of methods for determining equilibrium thermodynamic properties for hydrogen for several values of pressure and temperatures to 50000 K. A comparison is also performed between the present method and a second method for determining thermodynamic properties and flow velocity behind an incident shock into pure hydrogen and behind a reflected shock.

  20. MHD shocks in the ISM

    NASA Technical Reports Server (NTRS)

    Chernoff, D. F.; Hollenbach, David J.; Mckee, Christopher F.

    1990-01-01

    Researchers survey shock solutions of a partially ionized gas with a magnetic field. The gas is modeled by interacting neutral, ion, electron and charged grain components. They employ a small neutral-ion chemical network to follow the dissociation and ionization of the major species. Cooling by molecular hydrogen (rotational, vibrational and dissociation), grains and dipole molecules is included. There are three basic types of solutions (C, C asterisk, and J) and some more complicated flows involving combinations of the basic types. The initial preshock conditions cover hydrogen nuclei densities of 1 less than n less than 10(exp 10) cm(-3) and shock velocities of 5 less than v(sub s) less than 60 km/s. The magnetic field is varied over 5 decades and the sensitivity of the results to grain parameters, UV and cosmic ray fluxes is ascertained. The parameter space is quite complicated, but there exist some simple divisions. When the initial ionization fraction is small (chi sub i less than 10(-5)), there is a sharp transition between fully C solutions at low velocity and strong J solutions at high velocity. When the initial ionization fraction is larger, C asterisk and/or very weak J shocks are present at low velocities in addition to the C solutions. The flow again changes to strong J shocks at high velocities. When the ionization fraction is large and the flow is only slightly greater than the bulk Alfven velocity, there is a complicated mixture of C, C asterisk and J solutions.

  1. Scientific Evidence for Hydrostatic Shock

    DTIC Science & Technology

    2010-01-01

    device used to break up kidney stones with sonic pressure waves) produces no damage to soft tissues. Since a lithotriptor produces pressure waves...the Risk of Long-Term Complications in Shock Wave Lithotripsy , Nephron 78(1):1-8, 1998. 13. Lingeman JE, Kim SC, Keo RL, McAteer JA, Evan AP...Shockwave Lithotripsy : Anecdotes and Insights. Journal of Endourology 17(9):687-693; 2003. 14. Lokhandwalla M, Sturtevant B: Mechanical Haemolysis

  2. The Shock and Vibration Bulletin. Part 1. Welcome, Invited Papers, Shipboard Shock, Blast and Ground Shock, Shock Testing and Analysis

    DTIC Science & Technology

    1986-08-01

    Charles Moening. The Aerospace Corporation, Los Angeles, CA Pyrotechnic Shock I HE PRE-PULSE IN PYROSHOCK MEASUREMENT AND ANALYSIS A E. Galef, TRW...SESSION II G. Wasz. TRW, San Bernardino, CA A VIBROACOUSTIC DATABASE MAN’AGEMENT SYSTEM AND ITS APPLICATION FOR A PYROSHOCK DATABASE W. Henricks and...E. Morse, TRW Electronics and Defense, Redondo Beach, CA THE CONTROLLED RESPONSE OF RESONATING FIXTURES USED TO SIMULATE PYROSHOCK ENVIRONMENTS N

  3. A geometry for sub-nanosecond X-ray diffraction from laser-shocked polycrystalline foils

    SciTech Connect

    Wark, Justin; Higginbotham, Andrew; Kimminau, Giles; Murphy, William; Nagler, Bob; Whitcher, Thomas; Hawreliak, James; Kalantar, Dan; Butterfield, Martin; El-Dasher, Bassem; McNaney, James; Milathianaki, Despina; Lorenzana, Hector; Remington, Bruce; Davies, Huw; Thornton, Lee; Park, Nigel; Lukezic, Stan

    2007-12-12

    In situ picosecond X-ray diffraction has proved to be a useful tool in furthering our understanding of the response of shocked crystals at the lattice level. To date the vast majority of this work has used single crystals as the shocked samples, owing to their diffraction efficiency, although the study of the response of polycrystalline samples is clearly of interest for many applications. We present here the results of experiments to develop sub-nanosecond powder/polycrystalline diffraction using a cylindrical pinhole camera. By allowing the incident X-ray beam to impinge on the sample at non-normal angles, the response of grains making a variety of angles to the shock propagation direction can potentially be interrogated.

  4. On the origin of hot diamagnetic cavities near the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Thomsen, M. F.; Gosling, J. T.; Bame, S. J.; Quest, K. B.; Russell, C. T.

    1988-01-01

    The origin of hot diamagnetic cavities (HDCs) observed occasionally upstream from the earth's bow shock is investigated by examining the results of November 16, 1977, observation, when four of these events occurred on a single day, as well as plasma and field data from that day. The results suggest that HDCs may form as a result of an unusually strong interaction between shock-reflected ions and the incoming solar wind. It is proposed that this interaction stems from a temporary and localized reflection of a larger-than-normal fraction of the incident ions, which is stimulated by sudden changes in the upstream field orientation; the consequences of such a temporary overreflection are found to be consistent with many of the observed features of HDCs, including the strong slowing, deflection, and heating of the flow, as well as the localization, internal recoveries, and occasional formation upstream from the shock itself.

  5. Addressing the problem of uniform converging spherical shock wave in water

    NASA Astrophysics Data System (ADS)

    Nitishinskiy, M.; Efimov, S.; Yanuka, D.; Gurovich, V. Tz.; Krasik, Ya. E.

    2016-10-01

    Time-resolved parameters of plasma compressed by a shock wave generated by the underwater electrical explosion of a spherical wire array are presented. The plasma was preliminarily formed inside a capillary placed at the equatorial plane along the axis of the array. Temporal evolution analysis of Hα and C II spectral lines showed that the plasma density increases from its initial value of ˜3 × 1017 cm-3 up to ˜5.5 × 1017 cm-3 within 300 ± 25 ns. These results were found to be in agreement with those of the model that considers the adiabatic compression of the plasma by the converging capillary walls caused by interaction with the incident shock wave with a pressure of ˜3 × 109 Pa at a radius of 1.5 mm. The latter results coincide well with those of the 1D hydrodynamic modeling, which assumes uniformity of the converging shock wave.

  6. Replication of grazing incidence optics

    NASA Technical Reports Server (NTRS)

    Ulmer, Melville P.

    1986-01-01

    The replication of grazing incidence optics is reviewed. Electroform and epoxy replication are described and compared. It is concluded that for light weight and deep nesting, replication has a distinct advantage over direct production. The resolution of optics produced in this manner is however, limited to about 10 arc seconds; a typical value is 40 arc seconds. Epoxy replicated pieces tend to have better optical figures than electroformed optics, but the latter can be made thinner to make more deeply nested systems.

  7. Proton Acceleration at Oblique Shocks

    NASA Astrophysics Data System (ADS)

    Galinsky, V. L.; Shevchenko, V. I.

    2011-06-01

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  8. Shock Initiation of Heterogeneous Explosives

    SciTech Connect

    Reaugh, J E

    2004-05-10

    The fundamental picture that shock initiation in heterogeneous explosives is caused by the linking of hot spots formed at inhomogeneities was put forward by several researchers in the 1950's and 1960's, and more recently. Our work uses the computer hardware and software developed in the Advanced Simulation and Computing (ASC) program of the U.S. Department of Energy to explicitly include heterogeneities at the scale of the explosive grains and to calculate the consequences of realistic although approximate models of explosive behavior. Our simulations are performed with ALE-3D, a three-dimensional, elastic-plastic-hydrodynamic Arbitrary Lagrange-Euler finite-difference program, which includes chemical kinetics and heat transfer, and which is under development at this laboratory. We developed the parameter values for a reactive-flow model to describe the non-ideal detonation behavior of an HMX-based explosive from the results of grain-scale simulations. In doing so, we reduced the number of free parameters that are inferred from comparison with experiment to a single one - the characteristic defect dimension. We also performed simulations of the run to detonation in small volumes of explosive. These simulations illustrate the development of the reaction zone and the acceleration of the shock front as the flame fronts start from hot spots, grow, and interact behind the shock front. In this way, our grain-scale simulations can also connect to continuum experiments directly.

  9. Shock dynamics of phase diagrams

    SciTech Connect

    Moro, Antonio

    2014-04-15

    A thermodynamic phase transition denotes a drastic change of state of a physical system due to a continuous change of thermodynamic variables, as for instance pressure and temperature. The classical van der Waals equation of state is the simplest model that predicts the occurrence of a critical point associated with the gas–liquid phase transition. Nevertheless, below the critical temperature theoretical predictions of the van der Waals theory significantly depart from the observed physical behaviour. We develop a novel approach to classical thermodynamics based on the solution of Maxwell relations for a generalised family of nonlocal entropy functions. This theory provides an exact mathematical description of discontinuities of the order parameter within the phase transition region, it explains the universal form of the equations of state and the occurrence of triple points in terms of the dynamics of nonlinear shock wave fronts. -- Highlights: •A new generalisation of van der Waals equation of state. •Description of phase transitions in terms of shock dynamics of state curves. •Proof of the universality of equations of state for a general class of models. •Interpretation of triple points as confluence of classical shock waves. •Correspondence table between thermodynamics and nonlinear conservation laws.

  10. Shock desensitizing of solid explosives

    SciTech Connect

    Davis, William C

    2010-01-01

    Solid explosive can be desensitized by a shockwave too weak to initiate it promptly, and desensitized explosive does not react although its chemical composition is almost unchanged. A strong second shock does not cause reaction until it overtakes the first shock. The first shock, if it is strong enough, accelerates very slowly at first, and then more rapidly as detonation approaches. These facts suggest that there are two competing reactions. One is the usual explosive goes to products with the release of energy, and the other is explosive goes to dead explosive with no chemical change and no energy release. The first reaction rate is very sensitive to the local state, and the second is only weakly so. At low pressure very little energy is released and the change to dead explosive dominates. At high pressure, quite the other way, most of the explosive goes to products. Numerous experiments in both the initiation and the full detonation regimes are discussed and compared in support of these ideas.

  11. Post electric shock reactive thrombocytosis.

    PubMed

    Katiyar, Richa; Patne, Shashikant C U; Pankaj, Pranjal

    2015-04-01

    Thrombocytosis is defined as a platelet count greater than 400×10(9)/L. Electric shock may lead to tissue injury and marked thrombocytosis. We herein report a case of 45-year-old woman, who was hospitalized with progressively increasing weakness, tingling sensation, and numbness of the bilateral lower limbs. She had a history of receiving electric shock during household work, 15 days prior to her admission. Her laboratory investigations revealed a markedly increased platelet count (1,570×10(9)/L) along with increased level of serum uric acid (12 mg/dL), and mild increase in serum potassium (6.7 mmol/L), and serum alanine transaminase (50 U/L). She was treated with intravenous fluids, calcium, and multivitamins. Following hospitalization and treatment, condition of the patient improved, her symptoms resolved, and her platelet counts declined. We report this case because of rare presentation of marked thrombocytosis secondary to electric shock with a brief discussion on pathophysiology of this condition.

  12. PROTON ACCELERATION AT OBLIQUE SHOCKS

    SciTech Connect

    Galinsky, V. L.; Shevchenko, V. I.

    2011-06-20

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  13. Warmup in free-operant avoidance as a function of the response-shock = shock-shock interval.

    PubMed

    Hineline, P N

    1978-11-01

    Warmup effects, the repeated within-session transitions from ineffective to effective avoidance, were examined with rats on free-operant shock-delay procedures. The shock-shock and response-shock intervals were kept equal as they were varied. As measured by both response rates and shock rates, the magnitude of within-session change in performance was inversely related to the size of the manipulated intervals. The duration of warmup tended to decrease as the intervals were increased. This finding, that increased shock frequencies do not shorten the warmup, appears to be inconsistent with all interpretations of the warmup that have been offered to date. Late-session performances replicated general features of prior experiments, but differed with respect to details of secondary conclusions in previous reports. These differences may stem from the selection of especially proficient avoiders for previous experiments.

  14. Early Warning: Development of Confidential Incident Reporting Systems

    NASA Technical Reports Server (NTRS)

    OLeary, Mike J.; Chappell, Sheryl L.; Connell, Linda (Technical Monitor)

    1996-01-01

    Accidents hardly ever happen without warning. The combination, or sequence, of failures and mistakes that cause an accident may indeed be unique but the individual failures and mistakes rarely are. In the USA in 1974 the crews on two different aircraft misunderstood the same aeronautical chart and descended towards their destination dangerously early towards a mountain. The first crew were in good weather conditions and could see the mountain and resolved their misinterpretation of the chart. The second crew six weeks later were not so lucky. In cloud they had no clues to point out their mistake nor the presence of the mountain. The resulting crash and the ensuing inquiry, which brought to light the previous incident, shocked the country but gave it the impetus to instigate a safety reporting system. This system eventually became the NASA's Aviation Safety Reporting System (ASRS). The programme collects incident reports from pilots, controllers, mechanics, cabin attendants and many others involved in aviation operations. By disseminating this safety information the ASRS has helped enormously to give US airlines and airspace the highest safety standards. Accident prevention is a goal sought by everyone in the aviation industry and establishing effective incident reporting programmes can go a long way toward achieving that goal. This article will describe the steps and issues required to establish an incident reporting system. The authors summarize the lessons learned from the ASRS, now in its twentieth year of operation and from the Confidential Human Factors Reporting (HER) Programme run by British Airways, an airline that is a recognized world leader in safety reporting and analysis. The differences between government and airline operation of confidential safety reporting systems will be addressed.

  15. Impact of Shock Front Nonstationarity on the Acceleration of Heavy Ions by Perpendicular Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Lembege, B.; Lu, Q.

    2010-12-01

    Both hybrid /full particle simulations and recent experimental results have clearly evidenced that the front of a supercritical quasi-perpendicular shock can be nonstationary and corresponds to the self-reformation of the front itself being due to the accumulation of reflected ions. Not only the amplitude but also the spatial scales of fields components at the front (ramp and foot) are strongly varying within each cycle of the self- reformation. On the other hand, several studies have been made on the acceleration and heating of heavy ions but most have been restricted to a stationary shock profile only. Herein, one-dimensional test particle simulations with fields components issued from self-consistent 1D PIC simulation are performed in order to investigate the impact of shock front non-stationarity on heavy ion acceleration (He, O, Fe). Reflection and acceleration mechanisms of heavy ions with different initial thermal velocities and different charge-mass ratios interacting with a non-stationary shock front (self-reformation) are analyzed in detail. Present preliminary results show that: (i) the heavy ions suffer shock drift acceleration (SDA) and shock surfing acceleration (SSA) mechanisms and will be compared with previous works; (ii) the fraction of reflected heavy ions increases with initial kinetic energy, charge-mass ratio and decreasing shock front width at both stationary shock (situation equivalent to fixed shock regime) and non-stationary shocks (situation equivalent to a continously time-evolving shock regime); (iii) the shock front non-stationarity facilitates the reflection of heavy ions for broad (rather than narrow) shock profiles; (iv) high energy part of Fe/O ratio spectra at a non-stationary shock decreases with shock ramp width. The impact of the shock front non-stationarity on the heavy ions spectra within the shock front region and the downstream region will be also discussed.

  16. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    SciTech Connect

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal - incidence visible and near - infrared Shock Wave Optical Reflectivity Diagnostic (SWORD) was constructed to investigate changes in the optical properties of materials under dynamic laser compression . Documenting wavelength - and time - dependent changes in the optical properties of laser - shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved , but we succeeded in doing so by broadening a series of time delayed 800 - nm pulses from an ultra fast Ti: sapphire laser to generate high - intensity broadband light at nanosecond time scales . This diagnostic was demonstrated over the wavelength range 450 to 1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off - normal incidence velocity interferometry (VISAR) characterize d the sample under laser - compression , and also provide d a n independent reflectivity measurement at 532 nm wavelength . Lastly, the shock - driven semiconductor - to - metallic transition in germanium was documented by way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm .

  17. Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones

    SciTech Connect

    Desjouy, C. Ollivier, S.; Dragna, D.; Blanc-Benon, P.; Marsden, O.

    2015-10-28

    The study of acoustic shock propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic shocks, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak shock waves between parallel rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular – also called Von Neumann – regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic shock waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.

  18. Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones

    NASA Astrophysics Data System (ADS)

    Desjouy, C.; Ollivier, S.; Marsden, O.; Dragna, D.; Blanc-Benon, P.

    2015-10-01

    The study of acoustic shock propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic shocks, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak shock waves between parallel rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular - also called Von Neumann - regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic shock waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.

  19. The Shock and Vibration Bulletin. Part 3. Shock Testing, Shock Analysis

    DTIC Science & Technology

    1974-08-01

    unlari practice for a!-’ pyrotechnic shock ani 16. It. is ýf interest týý pxori;.e wand co- tezts because of bad expo-rlences with other %are the tr-u~ loi ...souid di;turbance over a measured dis- height, each charge weighing 1.5 lbs. nominally. tauce . Soil density and water content measure- Each charge was

  20. The Shock and Vibration Bulletin. Part 3. Invited Papers, Pyrotechnic Shock, Pyrotechnic Shock Workshop

    DTIC Science & Technology

    1986-08-01

    Rocketdyne, Session II, San Bernardino, CA Canoga Park, CA Instrumentation, Data Acquisition, and Data Bank Wednesday Pyroshock Mr. Dan Powers, Mr. Robert...8217 CAO ul .1~ II PYROTECHNIC SHOCK THE PRE-PULSE IN PYROSHOCK MEASUREMENT AND ANALYSIS A. E. Galef I TRW Electronics and Defense Redondo Beach...resulting valid data on pyroshocks available. This would from the very short duration, small net impulse be an exaggeration of my position, since the of the

  1. Melanoma incidence and frequency modulation (FM) broadcasting.

    PubMed

    Hallberg, Orjan; Johansson, Olle

    2002-01-01

    The incidence of melanoma has been increasing steadily in many countries since 1960, but the underlying mechanism causing this increase remains elusive. The incidence of melanoma has been linked to the distance to frequency modulation (FM) broadcasting towers. In the current study, the authors sought to determine if there was also a related link on a larger scale for entire countries. Exposure-time-specific incidence was extracted from exposure and incidence data from 4 different countries, and this was compared with reported age-specific incidence of melanoma. Geographic differences in melanoma incidence were compared with the magnitude of this environmental stress. The exposure-time-specific incidence from all 4 countries became almost identical, and they were approximately equal to the reported age-specific incidence of melanoma. A correlation between melanoma incidence and the number of locally receivable FM transmitters was found. The authors concluded that melanoma is associated with exposure to FM broadcasting.

  2. Geomagnetic avtivity triggered by interplanetary shocks: The shock impact angle as a controlling factor

    NASA Astrophysics Data System (ADS)

    Oliveira, D. M.; Raeder, J.; Tsurutani, B.; Gjerloev, J. W.

    2015-12-01

    We study the influence of interplanetary (IP) shock impact angles in the shock geoeffectiveness focusing on simulations and observations. In our simulations, we use OpenGGCM simulations to study the magnetospheric and ionospheric responses to shock impacts. Three cases are presented here: two inclined shocks, with 3.7 and 7.4 Mach numbers, and a frontal shock, whose shock normal is along the Sun-Earth line, with Mach number of 7.4. We find that, in the two inclined cases, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the magnetotail is compressed from both sides symmetrically. This compression triggers a substorm. By comparing the strong inclined shock and the frontal shock, we find that, despite the inclined shock having a larger Mach number, the frontal shock leads to a larger geomagnetic response in the nightside ionosphere. As a result, we conclude that IP shocks with similar upstream conditions, such as Mach number, can have different geoeffectiveness, depending on their shock normal orientation. In our observational study, we present a survey of IP shocks at 1 AU using Wind and ACE satellite data from Jan 1995 to Dec 2013 to study the same shock-related effects. A shock list covering one and a half solar cycle is compiled. We use data from SuperMAG, a large chain with more than 300 geomagnetic stations, to study geoeffectiveness triggered by IP shocks. The SuperMAG SML index (enhanced AL index), is used to quantify substorm strength. The jumps of the SML index triggered by shock impacts is investigated in terms of shock orientation and speed. We find that, in general, strong and almost frontal shocks are more geoeffective than inclined shocks with low speed. The highest correlations (R = 0.78) occurs for fixed shock speed and varying the shock impact angle. We attribute this result

  3. Shock metamorphism of lunar and terrestrial basalts

    NASA Technical Reports Server (NTRS)

    Schaal, R. B.; Hoerz, F.

    1977-01-01

    Lonar Crater (India) basalt and lunar basalt 75035 were shock loaded under controlled laboratory conditions up to 1000 kbar, generally in a CO/CO2 (1:1) environment evacuated to 10 to the minus seventh power torr. The Kieffer et al. (1976) classification scheme of progressive shock metamorphism is found to apply to lunar basalts. The major shock features of the five classes that span the range 0 to 1000 kbar are described. Only three out of 152 basalt specimens show shock effects in their natural state as severe as Class 2 features. The scarcity of shocked basalt hand samples in contrast to the abundance of shock-produced agglutinates and homogeneous glass spheres in the lunar regolith indicates the dominant role of micrometeorite impact in the evolution of the lunar regolith. The overall glass content in asteroidal and Mercurian regoliths is considered.

  4. Shock compression dynamics under a microscope

    NASA Astrophysics Data System (ADS)

    Dlott, Dana D.

    2017-01-01

    Our laboratory has developed a tabletop laser miniflyer launcher used for a wide variety of studies in the physical and chemical sciences. The flyers, typically 0.7 mm in diameter, can be used to shock microgram quantities of interesting materials. Frequently 100 shock experiments per day are performed. A microscope objective transmits the photon Doppler velocimeter (PDV) flyer plate diagnostic and various laser beams, and collects signals from the shocked materials that can be transmitted to video cameras, spectrographs, streak cameras, etc. In this paper I describe the flyer plate apparatus and then discuss three recent efforts: (1) Shock dissipation in nanoporous media; (2) Probing micropressures in shocked microstructured media; and (3) Shock initiation of nanotechnology reactive materials.

  5. Standing shocks in a rotating channel

    NASA Astrophysics Data System (ADS)

    Jacobson, Tivon E.; Tabak, Esteban G.

    2004-10-01

    This paper discusses the stationary shallow water shocks occurring in a reentrant rotating channel with wind stress and topography. Asymptotic predictions for the shock location, strength, and associated energy dissipation are developed by taking the topographic perturbation to be small. It is shown that under appropriate conditions, a mean flow develops under the action of the wind stress, with a transverse profile determined by the need to support stationary shocks. The scaling arguments for the asymptotics are developed by demanding integrated energy and momentum balance, with the result that the free surface perturbation is of the order of the square root of the topographic perturbation. Shock formation requires that linear waves be nondispersive, which sets a solvability condition on the mean flow and which leads to a class of generalized Kelvin waves. Two-dimensional shock-resolving numerical simulations validate the asymptotic expressions and demonstrate the presence of stationary separated flow shocks in some cases.

  6. Remote shock sensing and notification system

    DOEpatents

    Muralidharan, Govindarajan; Britton, Charles L.; Pearce, James; Jagadish, Usha; Sikka, Vinod K.

    2008-11-11

    A low-power shock sensing system includes at least one shock sensor physically coupled to a chemical storage tank to be monitored for impacts, and an RF transmitter which is in a low-power idle state in the absence of a triggering signal. The system includes interference circuitry including or activated by the shock sensor, wherein an output of the interface circuitry is coupled to an input of the RF transmitter. The interface circuitry triggers the RF transmitting with the triggering signal to transmit an alarm message to at least one remote location when the sensor senses a shock greater than a predetermined threshold. In one embodiment the shock sensor is a shock switch which provides an open and a closed state, the open state being a low power idle state.

  7. Remote shock sensing and notification system

    DOEpatents

    Muralidharan, Govindarajan [Knoxville, TN; Britton, Charles L [Alcoa, TN; Pearce, James [Lenoir City, TN; Jagadish, Usha [Knoxville, TN; Sikka, Vinod K [Oak Ridge, TN

    2010-11-02

    A low-power shock sensing system includes at least one shock sensor physically coupled to a chemical storage tank to be monitored for impacts, and an RF transmitter which is in a low-power idle state in the absence of a triggering signal. The system includes interface circuitry including or activated by the shock sensor, wherein an output of the interface circuitry is coupled to an input of the RF transmitter. The interface circuitry triggers the RF transmitter with the triggering signal to transmit an alarm message to at least one remote location when the sensor senses a shock greater than a predetermined threshold. In one embodiment the shock sensor is a shock switch which provides an open and a closed state, the open state being a low power idle state.

  8. Shock metamorphic effects in lunar microcraters

    NASA Technical Reports Server (NTRS)

    Schaal, R. B.; Hoerz, F.; Gibbons, R. V.

    1976-01-01

    Detailed petrographic descriptions and results of electron microprobe analyses are presented for impact glasses as well as shocked and unshocked minerals associated with individual lunar microcraters (diameters of 0.4 to 4.4 mm). Rocks of four typical lunar lithologies are studied: anorthosite, anorthositic norite, ophitic basalt, and polymict breccia. Textures, mineralogies, and chemical compositions are examined along a radial traverse through each microcrater; i.e., across the impact glasses lining the crater wall, the shock-metamorphosed zone immediately underlying the glass liner, and the unshocked host rock. The microcraters are discussed in a sequence of increasing mineralogical complexity of the host rock (from anorthosite to polymict breccia) in order to distinguish shock effects among mineral types. The shock metamorphic features observed are found to be comparable to those reported in shocked basalt from Lonar Crater, India, and are categorized into five shock-intensity classes with pressures experimentally calibrated.

  9. Entropy Generation Across Earth's Bow Shock

    NASA Technical Reports Server (NTRS)

    Parks, George K.; McCarthy, Michael; Fu, Suiyan; Lee E. s; Cao, Jinbin; Goldstein, Melvyn L.; Canu, Patrick; Dandouras, Iannis S.; Reme, Henri; Fazakerley, Andrew; Lin, Naiguo; Wilber, Mark

    2011-01-01

    Earth's bow shock is a transition layer that causes an irreversible change in the state of plasma that is stationary in time. Theories predict entropy increases across the bow shock but entropy has never been directly measured. Cluster and Double Star plasma experiments measure 3D plasma distributions upstream and downstream of the bow shock that allow calculation of Boltzmann's entropy function H and his famous H-theorem, dH/dt O. We present the first direct measurements of entropy density changes across Earth's bow shock. We will show that this entropy generation may be part of the processes that produce the non-thermal plasma distributions is consistent with a kinetic entropy flux model derived from the collisionless Boltzmann equation, giving strong support that solar wind's total entropy across the bow shock remains unchanged. As far as we know, our results are not explained by any existing shock models and should be of interests to theorists.

  10. Exhaust Nozzle Plume and Shock Wave Interaction

    NASA Technical Reports Server (NTRS)

    Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

    2013-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

  11. Effects of shock pressures on calcic plagioclase

    NASA Technical Reports Server (NTRS)

    Gibbons, R. V.; Ahrens, T. J.

    1977-01-01

    Calcic plagioclase single crystals were subjected to shock loading up to a pressure of 496 kbar; optical and electron microscope studies were conducted to investigate the shock-induced effects on the mineral, which is found in terrestrial and lunar rocks and in meteorites. It was observed that up to 287 kbar pressure, the recovered samples are essentially crystalline, while samples subjected to pressures between 300 and 400 kbar are almost 100% diaplectic glasses, suggesting shock transformation in the solid state. Samples shock-loaded to pressures greater than 400 kbar yielded glasses with refractive indices similar to those of thermally fused glass. It is concluded that planar features, absent in all the specimens, may not be definitive shock indicators, but may be linked to local heterogeneous dynamic stresses experienced by plagioclase grains within shocked rocks.

  12. X-ray diffraction studies of shocked lunar analogs

    NASA Technical Reports Server (NTRS)

    Hanss, R. E.

    1979-01-01

    The X-ray diffraction experiments on shocked rock and mineral analogs of particular significance to lunar geology are described. Materials naturally shocked by meteorite impact, nuclear-shocked, or artificially shocked in a flat plate accelerator were utilized. Four areas were outlined for investigation: powder diffractometer studies of shocked single crystal silicate minerals (quartz, orthoclase, oligoclase, pyroxene), powder diffractometer studies of shocked polycrystalline monomineralic samples (dunite), Debye-Scherrer studies of single grains of shocked granodiorite, and powder diffractometer studies of shocked whole rock samples. Quantitative interpretation of peak shock pressures experienced by materials found in lunar or terrestrial impact structures is presented.

  13. Dependence of the Spectrum of Shock-Accelerated Ions on the Dynamics at the Shock Crossing

    NASA Astrophysics Data System (ADS)

    Gedalin, M.; Dröge, W.; Kartavykh, Y. Y.

    2016-12-01

    Diffusive shock acceleration (DSA) of ions occurs due to pitch-angle diffusion in the upstream and downstream regions of the shock and multiple crossing of the shock by these ions. The classical DSA theory implies continuity of the distribution at the shock transition and predicts a universal spectrum of accelerated particles, depending only on the ratio of the upstream and downstream fluid speeds. However, the ion dynamics at the shock front occurs within a collision-free region and is gyrophase dependent. The ions fluxes have to be continuous at the shock front. The matching conditions for the gyrophase-averaged distribution functions at the shock transition are formulated in terms of the transition and reflection probabilities. These probabilities depend on the shock angle and the magnetic compression as does the power spectrum of accelerated ions. Their spectral index is expressed in terms of the reflectivity. The spectrum is typically harder than the spectrum predicted by the classical DSA theory.

  14. Compressible gas properties of UF/sub 6/ for isentropic, normal shock, and oblique shock conditions

    SciTech Connect

    Harloff, G.J.

    1984-11-01

    Isentropic, normal shock, and oblique shock tables are given for the real gas UF/sub 6/ for Mach numbers up to 22. An evaluation of the real gas effects is given. A computer program listing is included.

  15. Two-dimensional particle simulation of a perpendicular shock with a shock rest frame model

    NASA Astrophysics Data System (ADS)

    Yamao, M.; Umeda, T.; Yamazaki, R.; Ogino, T.

    2009-12-01

    A two-dimensional shock-rest-frame model for particle simulations is developed. This model does not need a huge simulation domain in the propagation direction of the shock wave as previous simulation models do. We performed a two-dimensional full particle simulation of a perpendicular collisionless shock and compared with one-dimensional simulation results. In both simulations, the excited shock waves show almost the same time evolution, periodically reforming at the timescale of the downstream ion gyro-period. In the two-dimensional simulation, electrons are thermalized along the transverse magnetic field, and electromagnetic whistler mode waves are excited in the shock front region. The amplitude of the exited whistler mode waves is not so strong and the shock magnetic field keeps almost one-dimensional structure. The two-dimensional simulation also shows the absence of electrostatic solitary structures in the shock foot region, which is necessary for electron shock surfing acceleration.

  16. Shock and Awe: A Widely Misunderstood Effect

    DTIC Science & Technology

    2007-11-02

    the collapse of the Soviet Union, America is now the only super power, unequalled in terms of defense spending and technology. It is arguable that no...destruction of the World Trade Center ( WTC ) which achieved complete shock at strategic, operational, and tactical levels, but was not exploited. Had the...Analysis of Shock This term [shock] is sometimes applied to an event of special force or significance that causes disruption or collapse of mental or

  17. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, W.B.; Graham, R.A.; Morosin, B.

    1987-04-20

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolyte rendering the electrolyte electrochemically active. 2 figs.

  18. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, William B.; Graham, Robert A.; Morosin, Bruno

    1988-01-01

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolytes rendering the electrolyte electrochemically active.

  19. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, W.B.; Graham, R.A.; Morosin, B.

    1988-11-08

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolytes rendering the electrolyte electrochemically active. 2 figs.

  20. Survival of carbon grains in shocks

    NASA Technical Reports Server (NTRS)

    Seab, C. Gregory

    1990-01-01

    Supernova shocks play a significant part in the life of an interstellar grain. In a typical 10 to the 9th power year lifetime, a grain will be hit by an average of 10 shocks of 100 km s(sup -1) or greater velocity, and even more shocks of lower velocity. Evaluation of the results of this frequent shock processing is complicated by a number of uncertainties, but seems to give about 10 percent destruction of silicate grains and about half that for graphite grains. Because of the frequency of shocking, the mineralogy and sizes of the grain population is predominately determined by shock processing effects, and not by the initial grain nucleation and growth environment. One consequence of the significant role played by interstellar shocks is that a certain fraction (up to 5 percent) of the carbon should be transformed into the diamond phase. Diamond transformation is observed in the laboratory at threshold shock pressures easily obtainable in grain-grain collisions in supernova shocks. Yields for transforming graphite, amorphous carbon, glassy carbon, and other nearly pure carbon solids into diamond are quite high. Impurities up to at least the 10 percent level (for oxygen) are tolerated in the process. The typical size diamond expected from shock transformation agrees well with the observed sizes in the Lewis et al. findings in meteoritic material. Isotropic anomalies already contained in the grain are likely to be retained through the conversion process, while others may be implanted by the shock if the grain is close to the supernova. The meteoritic diamonds are likely to be the results of transformation of carbon grains in grain-grain collisions in supernova shock waves.

  1. Shock and Vibration Bulletin. No. 5

    DTIC Science & Technology

    1947-09-01

    The lack of basic knowledge on failures due to shock and vibration are discussed and some of the difficulties in obtaining such information are Pointed...cal phenomena involved in shock or vibra- tion has greatly outstripped advances in our basic knowledge of how and why the structures or components... excellent . "We, as well as many other sections in the Bureau, are particularly interested in shock effects on equipment aboard ship and to that end we

  2. The earth's foreshock, bow shock, and magnetosheath

    SciTech Connect

    Onsager, T.G.; Thomsen, M.F. )

    1991-01-01

    Studies directly pertaining to the earth's foreshock, bow shock, and magnetosheath are reviewed, and some comparisons are made with data on other planets. Topics considered in detail include the electron foreshock, the ion foreshock, the quasi-parallel shock, the quasi-perpendicular shock, and the magnetosheath. Information discussed spans a broad range of disciplines, from large-scale macroscopic plasma phenomena to small-scale microphysical interactions. 184 refs.

  3. Concussion Incidence in Professional Football

    PubMed Central

    Nathanson, John T.; Connolly, James G.; Yuk, Frank; Gometz, Alex; Rasouli, Jonathan; Lovell, Mark; Choudhri, Tanvir

    2016-01-01

    Background: In the United States alone, millions of athletes participate in sports with potential for head injury each year. Although poorly understood, possible long-term neurological consequences of repetitive sports-related concussions have received increased recognition and attention in recent years. A better understanding of the risk factors for concussion remains a public health priority. Despite the attention focused on mild traumatic brain injury (mTBI) in football, gaps remain in the understanding of the optimal methodology to determine concussion incidence and position-specific risk factors. Purpose: To calculate the rates of concussion in professional football players using established and novel metrics on a group and position-specific basis. Study Design: Case-control study; Level of evidence, 3. Methods: Athletes from the 2012-2013 and 2013-2014 National Football League (NFL) seasons were included in this analysis of publicly available data. Concussion incidence rates were analyzed using established (athlete exposure [AE], game position [GP]) and novel (position play [PP]) metrics cumulatively, by game unit and position type (offensive skill players and linemen, defensive skill players and linemen), and by position. Results: In 480 games, there were 292 concussions, resulting in 0.61 concussions per game (95% CI, 0.54-0.68), 6.61 concussions per 1000 AEs (95% CI, 5.85-7.37), 1.38 concussions per 100 GPs (95% CI, 1.22-1.54), and 0.17 concussions per 1000 PPs (95% CI, 0.15-0.19). Depending on the method of calculation, the relative order of at-risk positions changed. In addition, using the PP metric, offensive skill players had a significantly greater rate of concussion than offensive linemen, defensive skill players, and defensive linemen (P < .05). Conclusion: For this study period, concussion incidence by position and unit varied depending on which metric was used. Compared with AE and GP, the PP metric found that the relative risk of concussion for

  4. Secondary shock wave emissions from cavitation in lithotripsy

    NASA Astrophysics Data System (ADS)

    Chitnis, Parag V.; Cleveland, Robin O.

    2005-04-01

    We investigate the role of secondary shock waves (SSWs) generated by cavitation in lithotripsy. Acoustic pressure was measured with a fiber optic probe hydrophone and cavitation using a dual passive cavitation detector (PCD) consisting of two confocal transducers. An artificial stone (~7 mm diameter and ~9 mm length) was placed at the focus of an electrohydraulic lithotripter. The fiber was inserted through a hole drilled through the stone so that the tip was at the proximal surface. SSWs were identified by matching the time of arrival to that of the inertial collapse signature acquired by the PCD. Measurements of SSWs were obtained for 50% of SWs fired at 20 kV and 1 Hz. The peak positive pressure for the SSW was p+=33.7+/-14.8 MPa, which was comparable to the pressure induced by the incident SW (p+=42.6+/-6 MPa). The peak pressure in water was p+=23.2+/-4.4 MPa. The PCD also recorded acoustic emissions from forced collapse of pre-existing bubbles caused by the incident SW. We propose that both the reflection from the semi-rigid stone boundary and SSW from the forced collapse contribute to the observed increase in the peak pressure of the incident SW in presence of a stone. [Work supported by NIH.

  5. Shock Tube Measurements of Ignition Processes and Spray-Shock Wave Interactions

    DTIC Science & Technology

    2008-04-06

    of species time-histories for OH radicals and alkanes; (4) ignition delay times of n-dodecane, jet fuel and diesel using the aerosol shock tube...of n-dodecane, jet fuel and diesel using the aerosol shock tube technique; and (5) improving shock tube performance and modeling. (a) Papers... Octane and n-Heptane Oxidation,” Proceedings of the Combustion Institute 31 (2007) 321-328. T. C. Hanson, D. F. Davidson, R. K. Hanson, “Shock Induced

  6. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  7. Revisiting Shock Initiation Modeling of Homogeneous Explosives

    NASA Astrophysics Data System (ADS)

    Partom, Yehuda

    2013-04-01

    Shock initiation of homogeneous explosives has been a subject of research since the 1960s, with neat and sensitized nitromethane as the main materials for experiments. A shock initiation model of homogeneous explosives was established in the early 1960s. It involves a thermal explosion event at the shock entrance boundary, which develops into a superdetonation that overtakes the initial shock. In recent years, Sheffield and his group, using accurate experimental tools, were able to observe details of buildup of the superdetonation. There are many papers on modeling shock initiation of heterogeneous explosives, but there are only a few papers on modeling shock initiation of homogeneous explosives. In this article, bulk reaction reactive flow equations are used to model homogeneous shock initiation in an attempt to reproduce experimental data of Sheffield and his group. It was possible to reproduce the main features of the shock initiation process, including thermal explosion, superdetonation, input shock overtake, overdriven detonation after overtake, and the beginning of decay toward Chapman-Jouget (CJ) detonation. The time to overtake (TTO) as function of input pressure was also calculated and compared to the experimental TTO.

  8. Viscous shock profiles and primitive formulations

    NASA Technical Reports Server (NTRS)

    Karni, S.

    1990-01-01

    Weak solutions of hyperbolic systems in primitive (non-conservation) form for which a consistent conservation form exists are considered. It is shown that primitive formulations, shock relations are not uniquely defined by the states to either side of the shock but also depend on the viscous path connecting the two. Scheme-dependent high order correction terms are derived that enforce consistent viscous shock profiles. The resulting primitive algorithm is conservative to the order of approximation. One dimensional Euler calculations of flows containing strong shocks clearly show that conservation errors in primitive flow calculations are of comparable quality.

  9. Shock wave equation of state of muscovite

    NASA Technical Reports Server (NTRS)

    Sekine, Toshimori; Rubin, Allan M.; Ahrens, Thomas J.

    1991-01-01

    Shock wave data were obtained between 20 and 140 GPa for natural muscovite obtained from Methuen Township (Ontario), in order to provide a shock-wave equation of state for this crustal hydrous mineral. The shock equation of state data could be fit by a linear shock velocity (Us) versus particle velocity (Up) relation Us = 4.62 + 1.27 Up (km/s). Third-order Birch-Murnaghan equation of state parameters were found to be K(OS) = 52 +/-4 GPa and K-prime(OS) = 3.2 +/-0.3 GPa. These parameters are comparable to those of other hydrous minerals such as brucite, serpentine, and tremolite.

  10. Accretion shock geometries in the magnetic variables

    NASA Technical Reports Server (NTRS)

    Stockman, H. S.

    1988-01-01

    The first self consistent shock models for the AM Herculis-type systems successfully identified the dominant physical processes and their signatures. These homogenous shock models predict unpolarized, Rayleigh-Jeans optical spectra with sharp cutoffs and rising polarizations as the shocks become optically thin in the ultraviolet. However, the observed energy distributions are generally flat with intermediate polarizations over a broad optical band. These and other observational evidence support a non-homogenous accretion profile which may extend over a considerable fraction of the stellar surface. Both the fundamental assumptions underlying the canonical 1-D shock model and the extension of this model to inhomogenous accretion shocks were identified, for both radial and linear structures. The observational evidence was also examined for tall shocks and little evidence was found for relative shock heights in excess of h/R(1) greater than or equal to 0.1. For several systems, upper limits to the shock height can be obtained from either x ray or optical data. These lie in the region h/R(1) is approximately 0.01 and are in general agreement with the current physical picture for these systems. The quasi-periodic optical variations observed in several magnetic variables may eventually prove to be a major aid in further understanding their accretion shock geometries.

  11. Sub-photospheric Shocks in Relativistic Explosions

    NASA Astrophysics Data System (ADS)

    Beloborodov, Andrei M.

    2017-04-01

    This paper examines the mechanism of internal shocks in opaque relativistic outflows, in particular in cosmological gamma-ray bursts. The shocks produce neutrino emission and affect the observed photospheric radiation from the explosion. They develop from internal compressive waves and can be of different types depending on the composition of the outflow. (1) Shocks in “photon gas,” with negligible plasma inertia, have a unique structure determined by the force-free condition—zero radiation flux in the plasma rest frame. Radiation dominance over plasma inertia suppresses the formation of collisionless shocks mediated by collective electromagnetic fields. (2) If the outflow is sufficiently magnetized, a strong collisionless subshock develops, which is embedded in a thicker radiation-mediated structure. (3) Waves in outflows with a free neutron component lead to dissipation through nuclear collisions. At large optical depths, shocks have a thickness comparable to the neutron free path, with embedded radiation-mediated and collisionless subshocks. The paper also presents first-principles simulations of magnetized flows filled with photons, demonstrating the formation of shocks and their structure. Simple estimates show that magnetized sub-photospheric shocks are efficient producers of photons and have a great impact on the observed photospheric radiation. The shock structure changes as the outflow expands toward its photosphere. The dissipation is accompanied by strong {e}+/- pair creation, and the {e}+/- -dressed shock carries the photosphere with it up to two decades in radius, emitting a strong pulse of nonthermal radiation.

  12. Basic Shock Physiology and Critical Care.

    PubMed

    Roberts, Brian K

    2016-05-01

    Veterinarians practicing emergency medicine and/or working with exotic animals must be well versed in the pathophysiology of shock because many exotic pets present with an acute crisis or an acute manifestation of a chronic process causing poor organ perfusion. This article discusses the pathophysiology of shock and the systemic inflammatory response syndrome, which may lead to organ dysfunction, organ failure, sepsis, and death. The physiology of perfusion, perfusion measurements, categories of shock, and altered function of the immune system, gastrointestinal barrier, and coagulation system are discussed. Veterinarians providing emergency care to patients with shock must also be aware of comorbidities.

  13. Dimension limit for thermal shock failure

    NASA Astrophysics Data System (ADS)

    Shao, Y. F.; Liu, Q. N.; Tian, H. J.; Lin, Z. K.; Xu, X. H.; Song, F.

    2014-08-01

    We analytically present the characteristic dimensional limit below which the thermal shock failure of ceramics never occurs. This limit, together with the critical temperature difference, separates the state space of the ceramics under thermal shock into two parts - the cracked and the uncracked. Based on the water-quench tests of ceramics, we experimentally proved that when the states of ceramics are in the uncracked region, the ceramics do not produce any cracks during thermal shock. The results provide a guide to prevent thermal shock failure in ceramic.

  14. Reclassifying the spectrum of septic patients using lactate: severe sepsis, cryptic shock, vasoplegic shock and dysoxic shock

    PubMed Central

    Ranzani, Otavio Tavares; Monteiro, Mariana Barbosa; Ferreira, Elaine Maria; Santos, Sergio Ricardo; Machado, Flavia Ribeiro; Noritomi, Danilo Teixeira

    2013-01-01

    Objective The current definition of severe sepsis and septic shock includes a heterogeneous profile of patients. Although the prognostic value of hyperlactatemia is well established, hyperlactatemia is observed in patients with and without shock. The present study aimed to compare the prognosis of septic patients by stratifying them according to two factors: hyperlactatemia and persistent hypotension. Methods The present study is a secondary analysis of an observational study conducted in ten hospitals in Brazil (Rede Amil - SP). Septic patients with initial lactate measurements in the first 6 hours of diagnosis were included and divided into 4 groups according to hyperlactatemia (lactate >4mmol/L) and persistent hypotension: (1) severe sepsis (without both criteria); (2) cryptic shock (hyperlactatemia without persistent hypotension); (3) vasoplegic shock (persistent hypotension without hyperlactatemia); and (4) dysoxic shock (both criteria). Results In total, 1,948 patients were analyzed, and the sepsis group represented 52% of the patients, followed by 28% with vasoplegic shock, 12% with dysoxic shock and 8% with cryptic shock. Survival at 28 days differed among the groups (p<0.001). Survival was highest among the severe sepsis group (69%, p<0.001 versus others), similar in the cryptic and vasoplegic shock groups (53%, p=0.39), and lowest in the dysoxic shock group (38%, p<0.001 versus others). In the adjusted analysis, the survival at 28 days remained different among the groups (p<0.001) and the dysoxic shock group exhibited the highest hazard ratio (HR=2.99, 95%CI 2.21-4.05). Conclusion The definition of sepsis includes four different profiles if we consider the presence of hyperlactatemia. Further studies are needed to better characterize septic patients, to understand the etiology and to design adequate targeted treatments. PMID:24553507

  15. 78 FR 38949 - Computer Security Incident Coordination (CSIC): Providing Timely Cyber Incident Response

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... National Institute of Standards and Technology Computer Security Incident Coordination (CSIC): Providing... Technology (NIST) is seeking information relating to Computer Security Incident Coordination (CSIC). NIST is... Computer Security Incident Response Teams (CSIRTs) to coordinate effectively when responding to...

  16. D-25 OBSERVATIONS OF SHOCKED METALLIC SURFACES WITH SINGLE-PULSE X-RAY DIFFRACTION

    SciTech Connect

    Morgan, D. V.; Grover, M.; Macy, D.; Madlener, M.; Stevens, G.; Turley, W. D.; Veeser, L.

    2009-01-01

    A single-pulse x-ray diffraction (XRD) diagnostic has been developed for the investigation of shocked material properties on a very short time scale. The diagnostic, which consists of a 37-stage Marx bank high-voltage pulse generator coupled to a needle-and-washer electron beam diode via coaxial cable, produces line and bremsstrahlung x-ray emission in a 40-ns pulse. A selected anode of either silver or molybdenum produces characteristic K lines used for diffraction. The x-ray beam passes through a pinhole collimator and is incident on the sample with an approximately 2-mm by 5-mm spot and 1° full-width-half-maximum angular divergence. Coherent scattering from the sample produces a Debye-Scherrer diffraction pattern on an image plate 75 mm from the polycrystalline sample surface. An experimental study of the polycrystalline structures of zirconium and tin under high-pressure shock loading has been conducted with single-pulse XRD. The experimental targets were 0.1-mm-thick foils of zirconium and tin using 0.4-mm-thick vitreous carbon back windows for shock-loading, and the shocks were produced by either Detasheet or PBX-9501 high explosives buffered by 1-mm-thick 6061-T6 aluminum. The diffraction patterns from both shocked zirconium and tin indicated a phase transition into a polymorphic mix of amorphous and new solid phases.

  17. Computational Meso-Scale Study of Representative Unit Cubes for Inert Spheres Subject to Intense Shocks

    NASA Astrophysics Data System (ADS)

    Stewart, Cameron; Najjar, Fady; Stewart, D. Scott; Bdzil, John

    2012-11-01

    Modern-engineered high explosive (HE) materials can consist of a matrix of solid, inert particles embedded into an HE charge. When this charge is detonated, intense shock waves are generated. As these intense shocks interact with the inert particles, large deformations occur in the particles while the incident shock diffracts around the particle interface. We will present results from a series of 3-D DNS of an intense shock interacting with unit-cube configurations of inert particles embedded into nitromethane. The LLNL multi-physics massively parallel hydrodynamics code ALE3D is used to carry out high-resolution (4 million nodes) simulations. Three representative unit-cube configurations are considered: primitive cubic, face-centered and body-centered cubic for two particle material types of varying impedance ratios. Previous work has only looked at in-line particles configurations. We investigate the time evolution of the unit cell configurations, vorticity being generated by the shock interaction, as well as the velocity and acceleration of the particles until they reach the quasi-steady regime. LLNL-ABS-567694. CSS was supported by a summer internship through the HEDP program at LLNL. FMN's work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Impact of the indigenous flora in animal models of shock and sepsis.

    PubMed

    Wells, Carol L; Hess, Donavon J; Erlandsen, Stanley L

    2004-12-01

    Septicemia is currently the 10th leading cause of death in the United States, and shock and trauma patients are the source of much of the morbidity and mortality associated with septicemia. There is substantial evidence that the composition of the indigenous flora plays an important role in modulating outcome variables in animal models of shock and sepsis. Germ-free animals that lack an indigenous flora are not as susceptible to shock as their conventionally reared counterparts. And, in conventionally reared animals, the composition of the intestinal flora can also modulate outcome in shock and sepsis. For example, certain bacterial species/strains disseminate from the intestinal tract more easily than others, antibiotic-induced alterations of the flora can modulate the incidence of systemic spread, and a certain threshold number of intestinal bacteria facilitates extraintestinal dissemination. The composition of the intestinal flora can also affect intestinal permeability, the production of inflammatory mediators, and the responses of immune cells in extraintestinal sites. And, there is evidence that prior exposure to endotoxin, via either the oral or systemic route, can influence outcome in animals challenged with parenteral endotoxin, a widely used model of endotoxin shock. The general composition of intestinal flora of experimental animals can be characterized with relative ease. This knowledge can aid data interpretation, either to help explain irreproducible or expected results or to verify that observed differences are likely related to the dependent variable studied rather than the composition of the indigenous flora.

  19. Thermal Shock-resistant Cement

    SciTech Connect

    Sugama T.; Pyatina, T.; Gill, S.

    2012-02-01

    We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved

  20. [Traumatic shock--physiopathologic aspects].

    PubMed

    Fabiano, G; Pezzolla, A; Filograna, M A; Ferrarese, F

    2008-01-01

    Traumatic shock is a complex phenomenon that represents the culminating element of a series of events. It is, in fact, the outcome of an imbalance-decompensation of the organism's defence mechanisms, in which the oxygen supply to the mitochondria is hampered by a macro and/or microcirculation failure. Basically, it is a form of hypovolemic shock in which further factors have a role, including the activation of inflammation mediators. It should also be stressed that part of the cellular damage is caused by tissue reperfusion. Good hemodynamic compensation is maintained with loss of up to 30% of the circulation mass but, beyond this amount, a fall of the cardiac index, peripheral pO2, and an increase of blood lactates will ensue. Hypoxia causes capillary injury and increased permeability, resulting in the formation of edema and finally in loss of the self-regulating power of the microcirculation. Moreover, it strongly stimulates pro-inflammatory activation of the macrophages and the release of vasoactive substances, such as prostaglandins and thromboxanes. The inflammatory response is triggered by cascade systems (such as the complement, coagulation, kinins, fibrinolysis), cell elements (endothelium, leukocytes, macrophages, monocytes, mast cells) and the release of mediators (cytokines, proteolytic enzymes, histamine, etc.) and others interacting factors. In severe trauma, the inflammatory process extends beyond the local limits, maintaining and aggravating the state of shock and causing a Systemic Inflammatory Response Syndrome (SIRS), with involvement and injury of healthy organs and tissues even at a distance from the site of trauma, raising a risk of onset of ARDS (Acute Respiratory Distress Syndrome), sepsis, MODS (Multiple Organ Dysfunction Syndrome). Tissue reperfusion (reoxygenation) also induces the production of toxic metabolites, such as hydroxylated anions, superoxide, hydrogen peroxide: peroxidation of the phospholipid cell membranes alters the barrier

  1. Shock wave interaction with a thermal layer produced by a plasma sheet actuator

    NASA Astrophysics Data System (ADS)

    Koroteeva, E.; Znamenskaya, I.; Orlov, D.; Sysoev, N.

    2017-03-01

    This paper explores the phenomena associated with pulsed discharge energy deposition in the near-surface gas layer in front of a shock wave from the flow control perspective. The energy is deposited in 200 ns by a high-current distributed sliding discharge of a ‘plasma sheet’ type. The discharge, covering an area of 100× 30 mm2, is mounted on the top or bottom wall of a shock tube channel. In order to analyse the time scales of the pulsed discharge effect on an unsteady supersonic flow, we consider the propagation of a planar shock wave along the discharge surface area 50–500 μs after the discharge pulse. The processes in the discharge chamber are visualized experimentally using the shadowgraph method and modelled numerically using 2D/3D CFD simulations. The interaction between the planar shock wave and the discharge-induced thermal layer results in the formation of a lambda-shock configuration and the generation of vorticity in the flow behind the shock front. We determine the amount and spatial distribution of the electric energy rapidly transforming into heat by comparing the calculated flow patterns and the experimental shadow images. It is shown that the uniformity of the discharge energy distribution strongly affects the resulting flow dynamics. Regions of turbulent mixing in the near-surface gas are detected when the discharge energy is deposited non-uniformly along the plasma sheet. They account for the increase in the cooling rate of the discharge-induced thermal layer and significantly influence its interaction with an incident shock wave.

  2. What is the evidence for IABP in STEMI with and without cardiogenic shock?

    PubMed

    de Waha, Suzanne; Desch, Steffen; Eitel, Ingo; Fuernau, Georg; Lurz, Philipp; de Waha, Antoinette; Schuler, Gerhard; Thiele, Holger

    2012-06-01

    Intraaortic balloon pump (IABP) is the most widely used left ventricular support device in a variety of indications. This review focuses on the current literature and discusses the evidence of IABP in ST-elevation myocardial infarction (STEMI) with and without cardiogenic shock. In high-risk STEMI patients without cardiogenic shock several randomized clinical trials have been performed. The majority of the studies could not demonstrate an efficacy benefit for IABP as adjunctive therapy in comparison to standard treatment alone. Hence, recent meta-analyses could not reveal diverging mortality rates at a higher incidence of stroke and major bleedings with IABP use independent of the type of reperfusion therapy. IABP in STEMI patients with cardiogenic shock is recommended according to current American College of Cardiology/American Heart Association (AHA/ACC) and European Society of Cardiology (ESC) guidelines. In recent meta-analyses, IABP in cardiogenic shock complicated by STEMI has been shown to be associated with decreased mortality. However, these beneficial effects are limited to patients treated with thrombolysis, whereas in patients undergoing mechanical revascularization IABP therapy is associated with an increase in mortality. Nevertheless, these data only arise from prospective and retrospective cohort studies, as up to date only one very small randomized clinical trial has been completed. In summary, in high-risk STEMI patients without cardiogenic shock, current data do not support the use of IABP and should only be considered as a standby and bailout strategy if patients develop haemodynamic instability. Current data on IABP in patients with cardiogenic shock complicated by STEMI are scarce and highly limited due to the nonrandomized design of previous trials. However, according to current AHA/ACC and ESC guidelines its use is recommended. Although recent meta-analyses challenge current AHA/ACC/ESC guidelines, adequately powered randomized studies are

  3. Culture-Shock and Reverse-Culture Shock: Implications for Juniors Abroad and Seniors at Home.

    ERIC Educational Resources Information Center

    Hogan, John T.

    Thousands of college seniors who have returned from their junior year abroad may be enduring "reverse culture shock" or "reentry crisis." Social psychology and sociology, in the form of "sojourn research," has derived a developmental, stage specific model of culture shock and reverse culture shock, similar to the grieving process identified by…

  4. Relativistic shock spectra: A prediction

    NASA Technical Reports Server (NTRS)

    Katz, J. I.

    1994-01-01

    I argue that particles heated by relativistic shocks should assume an equilibrium energy distribution. This leads to a synchrotron spectrum F(sub nu) varies as nu(sup 1/3) up to approximately the critical frequency nu(sub 0) of an electron with the mean electron energy. Application to gamma ray bursts (GRB's) implies that a burst with 10(exp -5) erg/(sq cm s) of soft gamma-rays and h(nu(sub 0)) = 300 KeV should be about 18th magnitude in visible light and a few micro-Jy at 1 GHz (less if self-absorbed).

  5. Adaptive inertial shock-absorber

    NASA Astrophysics Data System (ADS)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  6. Self-Regulating Shock Absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1995-01-01

    Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

  7. Shock

    MedlinePlus

    ... How to Peform CPR Use “ICE” in Your Cell Phone Prepare for Disasters Communication With Your Family And ... the person unless he or she is in danger. Make sure the person is breathing and has ...

  8. Converging shocks in elastic-plastic solids.

    PubMed

    Ortega, A López; Lombardini, M; Hill, D J

    2011-11-01

    We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=e(s)(I(1))+e(h)(ρ,ς), where e(s) accounts for shear through the first invariant of the Cauchy-Green tensor, and e(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e(h)=e(h)(ρ), with a power-law dependence e(h) is proportional to ρ(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M is proportional to [log(1/R)](α), independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M is proportional to R(-(s-1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part e(h) is that of an ideal gas, is also tested, recovering the strong-shock limit M is proportional to R(-(s-1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the

  9. Converging shocks in elastic-plastic solids

    NASA Astrophysics Data System (ADS)

    López Ortega, A.; Lombardini, M.; Hill, D. J.

    2011-11-01

    We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=es(I1)+eh(ρ,ς), where es accounts for shear through the first invariant of the Cauchy-Green tensor, and eh represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., eh=eh(ρ), with a power-law dependence eh∝ρα, shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M∝[log(1/R)]α, independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M∝R-(s-1) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part eh is that of an ideal gas, is also tested, recovering the strong-shock limit M∝R-(s-1)/n(γ) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the hydrostatic part of the energy essentially commands the strong-shock behavior, the shear

  10. Laser-Driven Magnetized Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Schaeffer, Derek

    2016-10-01

    Collisionless shocks - supersonic plasma flows in which the interaction length scale is much shorter than the collisional mean free path - are common phenomena in space and astrophysical systems, including the solar wind, coronal mass ejections, supernovae remnants, and the jets of active galactic nuclei. These systems have been studied for decades, and in many the shocks are believed to efficiently accelerate particles to some of the highest observed energies. Only recently, however, have laser and diagnostic capabilities evolved sufficiently to allow the detailed study in the laboratory of the microphysics of collisionless shocks over a large parameter regime. We present experiments that demonstrate the formation of collisionless shocks utilizing the Phoenix laser laboratory and the LArge Plasma Device (LAPD) at UCLA. We also show recent observations of magnetized collisionless shocks on the Omega EP laser facility that extend the LAPD results to higher laser energy, background magnetic field, and ambient plasma density, and that may be relevant to recent experiments on strongly driven magnetic reconnection. Lastly, we discuss a new experimental regime for shocks with results from high-repetition (1 Hz), volumetric laser-driven measurements on the LAPD. These large parameter scales allow us to probe the formation physics of collisionless shocks over several Alfvénic Mach numbers (MA), from shock precursors (magnetosonic solitons with MA < 1) to subcritical (MA < 3) and supercritical (MA > 3) shocks. The results show that collisionless shocks can be generated using a laser-driven magnetic piston, and agree well with both 2D and 3D hybrid and PIC simulations. Additionally, using radiation-hydrodynamic modeling and measurements from multiple diagnostics, the different shock regimes are characterized with dimensionless formation parameters, allowing us to place disparate experiments in a common and predictive framework.

  11. Acceleration of positrons in supernova shocks

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.

    1992-01-01

    During this project we investigated the acceleration of leptons (electrons and positrons) in collisionless shock waves. In particular, we were interested in how leptons are accelerated in the blast waves existing in the remnants of supernova explosions. Supernova remnants (SNRs) have long been considered as the most likely source of galactic cosmic rays but no definite connection between SNRs and the cosmic rays seen at earth can be made. Only by understanding lepton acceleration in shocks can the rich SNR data base be properly used to understand cosmic ray origins. Our project was directed at the neglected aspects of lepton acceleration. We showed that the efficiency of lepton acceleration depended critically on the lepton injection energy. We showed that, even when infection effects are not important, that proton and lepton distribution functions produced by shocks are quite different in the critical energy range for producing the observed synchrotron emission. We also showed that transrelativistic effects produced proton spectra that were not in agreement with standard results from radio observations, but that the lepton spectra were, in fact, consistent with observations. We performed simulations of relativistic shocks (shocks where the flow speed is a sizable fraction of the speed of light) and discovered some interesting effects. We first demonstrated the power of the Monte Carlo technique by determining the shock jump conditions in relativistic shocks. We then proceeded to determine how relativistic shocks accelerate particles. We found that nonlinear relativistic shocks treat protons and leptons even more differently than nonrelativistic shocks. The transrelativistic effects on the shock structure from the heavy ion component reduces the lepton acceleration to a tiny fraction of the ion acceleration. This effect is dramatic even if high energy leptons (many times thermal energy) are injected, and was totally unexpected. Our results have important

  12. Shock Wave Technology and Application: An Update☆

    PubMed Central

    Rassweiler, Jens J.; Knoll, Thomas; Köhrmann, Kai-Uwe; McAteer, James A.; Lingeman, James E.; Cleveland, Robin O.; Bailey, Michael R.; Chaussy, Christian

    2012-01-01

    Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL. PMID:21354696

  13. A shock-tube determination of the CN ground state dissociation energy and electronic transition moments for the CN violet and red band systems

    NASA Technical Reports Server (NTRS)

    Arnold, J. O.; Nicholls, R. W.

    1973-01-01

    The CN ground state dissociation energy and the sum of squares of the electronic transition moments of the CN violet bands have been simultaneously determined from spectral emission measurements behind incident shock waves. The unshocked test gases were composed of various CO2-CO-N2-Ar mixtures, and the temperatures behind the incident shocks ranged from 3500 to 8000 K. The variation of the electronic transition moment with internuclear separation was found to be small for both the CN violet and red band systems.

  14. Shock finding on a moving-mesh - II. Hydrodynamic shocks in the Illustris universe

    NASA Astrophysics Data System (ADS)

    Schaal, Kevin; Springel, Volker; Pakmor, Rüdiger; Pfrommer, Christoph; Nelson, Dylan; Vogelsberger, Mark; Genel, Shy; Pillepich, Annalisa; Sijacki, Debora; Hernquist, Lars

    2016-10-01

    Hydrodynamical shocks are a manifestation of the non-linearity of the Euler equations and play a fundamental role in cosmological gas dynamics. In this work, we identify and analyse shocks in the Illustris simulation, and contrast the results with those of non-radiative runs. We show that simulations with more comprehensive physical models of galaxy formation pose new challenges for shock finding algorithms due to radiative cooling and star-forming processes, prompting us to develop a number of methodology improvements. We find in Illustris a total shock surface area which is about 1.4 times larger at the present epoch compared to non-radiative runs, and an energy dissipation rate at shocks which is higher by a factor of around 7. Remarkably, shocks with Mach numbers above and below mathcal {M}≈ 10 contribute about equally to the total dissipation across cosmic time. This is in sharp contrast to non-radiative simulations, and we demonstrate that a large part of the difference arises due to strong black hole radio-mode feedback in Illustris. We also provide an overview of the large diversity of shock morphologies, which includes complex networks of halo-internal shocks, shocks on to cosmic sheets, feedback shocks due to black holes and galactic winds, as well as ubiquitous accretion shocks. In high-redshift systems more massive than 1012 M⊙, we discover the existence of a double accretion shock pattern in haloes. They are created when gas streams along filaments without being shocked at the outer accretion shock, but then forms a second, roughly spherical accretion shock further inside.

  15. Shear shocks in fragile networks.

    PubMed

    Ulrich, Stephan; Upadhyaya, Nitin; van Opheusden, Bas; Vitelli, Vincenzo

    2013-12-24

    A minimal model for studying the mechanical properties of amorphous solids is a disordered network of point masses connected by unbreakable springs. At a critical value of its mean connectivity, such a network becomes fragile: it undergoes a rigidity transition signaled by a vanishing shear modulus and transverse sound speed. We investigate analytically and numerically the linear and nonlinear visco-elastic response of these fragile solids by probing how shear fronts propagate through them. Our approach, which we tentatively label shear front rheology, provides an alternative route to standard oscillatory rheology. In the linear regime, we observe at late times a diffusive broadening of the fronts controlled by an effective shear viscosity that diverges at the critical point. No matter how small the microscopic coefficient of dissipation, strongly disordered networks behave as if they were overdamped because energy is irreversibly leaked into diverging nonaffine fluctuations. Close to the transition, the regime of linear response becomes vanishingly small: the tiniest shear strains generate strongly nonlinear shear shock waves qualitatively different from their compressional counterparts in granular media. The inherent nonlinearities trigger an energy cascade from low to high frequency components that keep the network away from attaining the quasi-static limit. This mechanism, reminiscent of acoustic turbulence, causes a superdiffusive broadening of the shock width.

  16. Very low shock release pyromechanisms

    NASA Astrophysics Data System (ADS)

    Soulier, Grégory; Gaechter, J. Pierre

    2003-09-01

    Pyromechanisms have long been used in space for launchers and satellites applications, particularly for release or separation purposes, such as bolt cutters, release nuts, pyrovalves, etc. They offer a great variety of uses, a high potential between the power supplied and the weight on board with, at the same time, a high reliability. However, they also feature a drawback due to the high dynamics generated by their functioning. Pyroshocks levels may damage adjacent sensible equipments (eg electronic boxes, reaction wheels,...) and require to design damping systems or to remove those equipments from the shock source. In a mechanism using standard pyrodevices, shock generation comes from three sources: 1. Pyrotechnic reaction. 2. Energy from internal parts in motion. 3. The release of structural constraints. Devices developed by E. LACROIX have the objectives to avoid the two last ones by: Using heat and gas generated by pyrotechnic effects. Reducing speed of parts in motion. Reducing release speed of mechanical constraints. In this paper, LACROIX presents two products named "PYROSOFT" and "VIROSOFT " designed by LACROIX and supported by CNES Toulouse (French Space Agency). R&T contracts.

  17. Cavitation in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael R.; Crum, Lawrence A.; Sapozhnikov, Oleg A.; Evan, Andrew P.; McAteer, James A.; Colonius, Tim; Cleveland, Robin O.

    2003-10-01

    A case is presented for the important role of cavitation in stone comminution and tissue injury in shock wave lithotripsy (SWL). Confocal hydrophones and a coincidence algorithm were used to detect cavitation in kidney parenchyma. Elevated hydrostatic pressure dissolved cavitation nuclei and suppressed cell injury and stone comminution in vitro. A low-insertion-loss, thin, mylar film nearly eliminated stone erosion and crack formation only when in direct contact with the stone. This result indicates not only that cavitation is important in both cracking and erosion but also that bubbles act at the surface. Time inversion of the shock wave by use of a pressure-release reflector reduced the calculated pressure at bubble collapse and the measured depth of bubble-induced pits in aluminum. Correspondingly tissue injury in vivo was nearly eliminated. Cavitation was localized and intensified by the use of synchronously triggered, facing lithotripters. This dual pulse lithotripter enhanced comminution at its focus and reduced lysis in surrounding blood samples. The enhancement of comminution was lost when stones were placed in glycerol, which retarded bubble implosion. Thus, cavitation is important in comminution and injury and can be controlled to optimize efficacy and safety. [Work supported by NIH DK43381, DK55674, and FIRCA.

  18. Shock compression profiles in ceramics

    SciTech Connect

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  19. Optical observation of shock waves and cavitation bubbles in high intensity laser-induced shock processes.

    PubMed

    Martí-López, L; Ocaña, R; Porro, J A; Morales, M; Ocaña, J L

    2009-07-01

    We report an experimental study of the temporal and spatial dynamics of shock waves, cavitation bubbles, and sound waves generated in water during laser shock processing by single Nd:YAG laser pulses of nanosecond duration. A fast ICCD camera (2 ns gate time) was employed to record false schlieren photographs, schlieren photographs, and Mach-Zehnder interferograms of the zone surrounding the laser spot site on the target, an aluminum alloy sample. We recorded hemispherical shock fronts, cylindrical shock fronts, plane shock fronts, cavitation bubbles, and phase disturbance tracks.

  20. Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

    NASA Technical Reports Server (NTRS)

    Tadghighi, H.; Holz, R.; Farassat, F.; Lee, Yung-Jang

    1991-01-01

    A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

  1. Optical observation of shock waves and cavitation bubbles in high intensity laser-induced shock processes

    SciTech Connect

    Marti-Lopez, L.; Ocana, R.; Porro, J. A.; Morales, M.; Ocana, J. L.

    2009-07-01

    We report an experimental study of the temporal and spatial dynamics of shock waves, cavitation bubbles, and sound waves generated in water during laser shock processing by single Nd:YAG laser pulses of nanosecond duration. A fast ICCD camera (2 ns gate time) was employed to record false schlieren photographs, schlieren photographs, and Mach-Zehnder interferograms of the zone surrounding the laser spot site on the target, an aluminum alloy sample. We recorded hemispherical shock fronts, cylindrical shock fronts, plane shock fronts, cavitation bubbles, and phase disturbance tracks.

  2. Plasma Shock Wave Modification Experiments in a Temperature Compensated Shock Tube

    NASA Technical Reports Server (NTRS)

    Vine, Frances J.; Mankowski, John J.; Saeks, Richard E.; Chow, Alan S.

    2003-01-01

    A number of researchers have observed that the intensity of a shock wave is reduced when it passes through a weakly ionized plasma. While there is little doubt that the intensity of a shock is reduced when it propagates through a weakly ionized plasma, the major question associated with the research is whether the reduction in shock wave intensity is due to the plasma or the concomitant heating of the flow by the plasma generator. The goal of this paper is to describe a temperature compensated experiment in a "large" diameter shock tube with an external heating source, used to control the temperature in the shock tube independently of the plasma density.

  3. Biological Effects of Shock Waves on Infection

    NASA Astrophysics Data System (ADS)

    Gnanadhas, Divya Prakash; Janardhanraj, S.; Chakravortty, Dipshikha; Gopalan, Jagadeesh

    Shock waves have been successfully used for disintegrating kidney stones[1], noninvasive angiogenic approach[2] and for the treatment of osteoporosis[3]. Recently shock waves have been used to treat different medical conditions including intestinal anastomosis[4], wound healing[5], Kienböck's disease[6] and articular cartilage defects[7].

  4. Collisionless Electrostatic Shock Modeling and Simulation

    DTIC Science & Technology

    2016-10-21

    effects difficult for theoretical prediction, • Wave Dispersion • Wave-Particle Interaction • Various Wave Dissipation Mechanisms – Shock structure is an...unlimited. PA#16490 Details on Shock Physics Sources of Collisionless Wave Dissipation – Landau Damping: ● A form of wave-particle resonance. Resonant

  5. Benjamin Franklin and Shock-Induced Amnesia

    ERIC Educational Resources Information Center

    Finger, Stanley; Zaromb, Franklin

    2006-01-01

    Shock-induced amnesia received considerable attention after Cerletti popularized electroconvulsive shock therapy in the late 1930s. Yet, often overlooked is the fact that Benjamin Franklin recognized that passing electricity through the head could affect memory for the traumatic event. Franklin described his findings on himself and others in…

  6. Resuscitation of traumatic shock: a hemodynamic review.

    PubMed

    Cottingham, Christine A

    2006-01-01

    Shock, or tissue hypoperfusion, is a frequent complication from traumatic injury. Despite the etiology of the shock state, there is always some component of hypovolemia. The body's innate ability to compensate for impaired perfusion may mask clinical signs, leading to delays in treatment. This article presents an overview of these compensatory mechanisms and resuscitation strategies from the vantage point of routine hemodynamic monitoring.

  7. 33 CFR 159.105 - Shock test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Shock test. 159.105 Section 159.105 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with...

  8. 33 CFR 159.105 - Shock test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Shock test. 159.105 Section 159.105 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with...

  9. Vibrational energy transfer in shocked molecular crystals.

    PubMed

    Hooper, Joe

    2010-01-07

    We consider the process of establishing thermal equilibrium behind an ideal shock front in molecular crystals and its possible role in initiating chemical reaction at high shock pressures. A new theory of equilibration via multiphonon energy transfer is developed to treat the scattering of shock-induced phonons into internal molecular vibrations. Simple analytic forms are derived for the change in this energy transfer at different Hugoniot end states following shock compression. The total time required for thermal equilibration is found to be an order of magnitude or faster than proposed in previous work; in materials representative of explosive molecular crystals, equilibration is predicted to occur within a few picoseconds following the passage of an ideal shock wave. Recent molecular dynamics calculations are consistent with these time scales. The possibility of defect-induced temperature localization due purely to nonequilibrium phonon processes is studied by means of a simple model of the strain field around an inhomogeneity. The specific case of immobile straight dislocations is studied, and a region of enhanced energy transfer on the order of 5 nm is found. Due to the rapid establishment of thermal equilibrium, these regions are unrelated to the shock sensitivity of a material but may allow temperature localization at high shock pressures. Results also suggest that if any decomposition due to molecular collisions is occurring within the shock front itself, these collisions are not enhanced by any nonequilibrium thermal state.

  10. Slow shocks in coronal mass ejections

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.

    1989-01-01

    The possibility that slow-mode shock compression may produce at least some of the increased brightness observed at the leading edge of coronal mass ejections is investigated. Among the reasons given for the possible existence of slow shocks are the following: (1) transient velocities are often greater than the upstream sound speed but less than the Alfven speed, (2) the presence of a slow shock is consistent with the flat top observed in some transients, and (3) the lateral extension of slow shocks may be responsible for distributing adjacent structures as also seen on the observations. It is shown that there may be some difficulties with this suggestion for transients originating inside the closed-field region at the base of a preexisting coronal streamer. First of all, slow mode characteristics have difficulty emerging from the closed-field region at the streamer base so they can merge to form a slow shock, unless a preceding, large-amplitude disturbance opens the field lines. In addition, a slow shock cannot exist at the center of the streamer current sheet. Finally, numerical simulations demonstrate that at least the last two (and possibly all) of the above reasons for slow shocks can be satisfied by a disturbance whose leading edge propagates at the local fast-mode speed without any shocks. The leading portion of the transient that would be seen in white-light coronagraphs propagates at a speed either less than or equal to the fast-mode speed.

  11. 33 CFR 159.105 - Shock test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Shock test. 159.105 Section 159.105 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with...

  12. RECOLLIMATION SHOCKS IN MAGNETIZED RELATIVISTIC JETS

    SciTech Connect

    Mizuno, Yosuke; Rezzolla, Luciano; Gómez, Jose L.; Nishikawa, Ken-Ichi; Meli, Athina; Hardee, Philip E.

    2015-08-10

    We have performed two-dimensional special-relativistic magnetohydrodynamic simulations of non-equilibrium over-pressured relativistic jets in cylindrical geometry. Multiple stationary recollimation shock and rarefaction structures are produced along the jet by the nonlinear interaction of shocks and rarefaction waves excited at the interface between the jet and the surrounding ambient medium. Although initially the jet is kinematically dominated, we have considered axial, toroidal, and helical magnetic fields to investigate the effects of different magnetic-field topologies and strengths on the recollimation structures. We find that an axial field introduces a larger effective gas pressure and leads to stronger recollimation shocks and rarefactions, resulting in larger flow variations. The jet boost grows quadratically with the initial magnetic field. On the other hand, a toroidal field leads to weaker recollimation shocks and rarefactions, significantly modifying the jet structure after the first recollimation rarefaction and shock. The jet boost decreases systematically. For a helical field, instead, the behavior depends on the magnetic pitch, with a phenomenology that ranges between the one seen for axial and toroidal magnetic fields, respectively. In general, however, a helical magnetic field yields a more complex shock and rarefaction substructure close to the inlet that significantly modifies the jet structure. The differences in shock structure resulting from different field configurations and strengths may have observable consequences for disturbances propagating through a stationary recollimation shock.

  13. 33 CFR 159.105 - Shock test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Shock test. 159.105 Section 159.105 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with...

  14. Reformation and Microinstabilities at Perpendicular Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Umeda, T.; Kidani, Y.; Matsukiyo, S.; Yamazaki, R.

    2014-12-01

    Large-scale two-dimensional (2D) full particle-in-cell (PIC) simulations are carried out for studying the relationship between the dynamics of a perpendicular shock and microinstabilities generated at the shock foot. The structure and dynamics of collisionless shocks are generally determined by Alfven Mach number and plasma beta, while microinstabilities at the shock foot are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the ratio of the plasma-to-cyclotron frequency. With a fixed Alfven Mach number and plasma beta, the ratio of the upstream bulk velocity to the electron thermal velocity is given as a function of the ion-to-electron mass ratio. The present 2D full PIC simulations with a relatively low Alfven Mach number (MA ˜ 6) show that the modified two-stream instability is dominant with higher ion-to-electron mass ratios. It is also confirmed that waves propagating downstream are more enhanced at the shock foot near the shock ramp as the mass ratio becomes higher. The result suggests that these waves play a role in the modification of the dynamics of collisionless shocks through the interaction with shock front ripples.

  15. Shock-induced melting and rapid solidification

    SciTech Connect

    Nellis, W.J.; Gourdin, W.H.; Maple, M.B.

    1987-08-01

    Model calculations are presented to estimate that approx.50 GPa is required to completely shock melt metal powders with quenching at rates up to 10/sup 8/ K/s. Experiments are discussed for powders of a Cu-Zr alloy compacted in the usual way at 16 GPa and melted by shocking to 60 GPa. 12 refs.

  16. Recollimation Shocks in Magnetized Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Mizuno, Yosuke; Gómez, Jose L.; Nishikawa, Ken-Ichi; Meli, Athina; Hardee, Philip E.; Rezzolla, Luciano

    2015-08-01

    We have performed two-dimensional special-relativistic magnetohydrodynamic simulations of non-equilibrium over-pressured relativistic jets in cylindrical geometry. Multiple stationary recollimation shock and rarefaction structures are produced along the jet by the nonlinear interaction of shocks and rarefaction waves excited at the interface between the jet and the surrounding ambient medium. Although initially the jet is kinematically dominated, we have considered axial, toroidal, and helical magnetic fields to investigate the effects of different magnetic-field topologies and strengths on the recollimation structures. We find that an axial field introduces a larger effective gas pressure and leads to stronger recollimation shocks and rarefactions, resulting in larger flow variations. The jet boost grows quadratically with the initial magnetic field. On the other hand, a toroidal field leads to weaker recollimation shocks and rarefactions, significantly modifying the jet structure after the first recollimation rarefaction and shock. The jet boost decreases systematically. For a helical field, instead, the behavior depends on the magnetic pitch, with a phenomenology that ranges between the one seen for axial and toroidal magnetic fields, respectively. In general, however, a helical magnetic field yields a more complex shock and rarefaction substructure close to the inlet that significantly modifies the jet structure. The differences in shock structure resulting from different field configurations and strengths may have observable consequences for disturbances propagating through a stationary recollimation shock.

  17. Hydrodynamic Simulations of Gaseous Argon Shock Experiments

    NASA Astrophysics Data System (ADS)

    Garcia, Daniel; Dattelbaum, Dana; Goodwin, Peter; Morris, John; Sheffield, Stephen; Burkett, Michael

    2015-06-01

    The lack of published Argon gas shock data motivated an evaluation of the Argon Equation of State (EOS) in gas phase initial density regimes never before reached. In particular, these regimes include initial pressures in the range of 200-500 psi (0.025 - 0.056 g/cc) and initial shock velocities around 0.2 cm/ μs. The objective of the numerical evaluation was to develop a physical understanding of the EOS behavior of shocked and subsequently multiply re-shocked Argon gas initially pressurized to 200-500 psi through Pagosa numerical hydrodynamic simulations utilizing the SESAME equation of state. Pagosa is a Los Alamos National Laboratory 2-D and 3-D Eulerian hydrocode capable of modeling high velocity compressible flow with multiple materials. The approach involved the use of gas gun experiments to evaluate the shock and multiple re-shock behavior of pressurized Argon gas to validate Pagosa simulations and the SESAME EOS. Additionally, the diagnostic capability within the experiments allowed for the EOS to be fully constrained with measured shock velocity, particle velocity and temperature. The simulations demonstrate excellent agreement with the experiments in the shock velocity/particle velocity space, but note unanticipated differences in the ionization front temperatures.

  18. Mechanochemistry for shock wave energy dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William L.; Ren, Yi; Moore, Jeffrey S.; Dlott, Dana D.

    2017-01-01

    Using a laser-driven flyer-plate apparatus to launch 75 μm thick Al flyers up to 2.8 km/s, we developed a technique for detecting the attenuation of shock waves by mechanically-driven chemical reactions. The attenuating sample was spread on an ultrathin Au mirror deposited onto a glass window having a known Hugoniot. As shock energy exited the sample and passed through the mirror, into the glass, photonic Doppler velocimetry monitored the velocity profile of the ultrathin mirror. Knowing the window Hugoniot, the velocity profile could be quantitatively converted into a shock energy flux or fluence. The flux gave the temporal profile of the shock front, and showed how the shock front was reshaped by passing through the dissipative medium. The fluence, the time-integrated flux, showed how much shock energy was transmitted through the sample. Samples consisted of microgram quantities of carefully engineered organic compounds selected for their potential to undergo negative-volume chemistry. Post mortem analytical methods were used to confirm that shock dissipation was associated with shock-induced chemical reactions.

  19. Existence Regions of Shock Wave Triple Configurations

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Chernyshev, Mikhail V.

    2016-01-01

    The aim of the research is to create the classification for shock wave triple configurations and their existence regions of various types: type 1, type 2, type 3. Analytical solutions for limit Mach numbers and passing shock intensity that define existence region of every type of triple configuration have been acquired. The ratios that conjugate…

  20. PRECURSORS TO INTERSTELLAR SHOCKS OF SOLAR ORIGIN

    SciTech Connect

    Gurnett, D. A.; Kurth, W. S.; Stone, E. C.; Cummings, A. C.; Krimigis, S. M.; Decker, R. B.; Burlaga, L. F.

    2015-08-20

    On or about 2012 August 25, the Voyager 1 spacecraft crossed the heliopause into the nearby interstellar plasma. In the nearly three years that the spacecraft has been in interstellar space, three notable particle and field disturbances have been observed, each apparently associated with a shock wave propagating outward from the Sun. Here, we present a detailed analysis of the third and most impressive of these disturbances, with brief comparisons to the two previous events, both of which have been previously reported. The shock responsible for the third event was first detected on 2014 February 17 by the onset of narrowband radio emissions from the approaching shock, followed on 2014 May 13 by the abrupt appearance of intense electron plasma oscillations generated by electrons streaming outward ahead of the shock. Finally, the shock arrived on 2014 August 25, as indicated by a jump in the magnetic field strength and the plasma density. Various disturbances in the intensity and anisotropy of galactic cosmic rays were also observed ahead of the shock, some of which are believed to be caused by the reflection and acceleration of cosmic rays by the magnetic field jump at the shock, and/or by interactions with upstream plasma waves. Comparisons to the two previous weaker events show somewhat similar precursor effects, although differing in certain details. Many of these effects are very similar to those observed in the region called the “foreshock” that occurs upstream of planetary bow shocks, only on a vastly larger spatial scale.

  1. Floating shock fitting via Lagrangian adaptive meshes

    NASA Technical Reports Server (NTRS)

    Vanrosendale, John

    1994-01-01

    In recent works we have formulated a new approach to compressible flow simulation, combining the advantages of shock-fitting and shock-capturing. Using a cell-centered Roe scheme discretization on unstructured meshes, we warp the mesh while marching to steady state, so that mesh edges align with shocks and other discontinuities. This new algorithm, the Shock-fitting Lagrangian Adaptive Method (SLAM) is, in effect, a reliable shock-capturing algorithm which yields shock-fitted accuracy at convergence. Shock-capturing algorithms like this, which warp the mesh to yield shock-fitted accuracy, are new and relatively untried. However, their potential is clear. In the context of sonic booms, accurate calculation of near-field sonic boom signatures is critical to the design of the High Speed Civil Transport (HSCT). SLAM should allow computation of accurate N-wave pressure signatures on comparatively coarse meshes, significantly enhancing our ability to design low-boom configurations for high-speed aircraft.

  2. Shock-induced arrhythmogenesis in the myocardium

    NASA Astrophysics Data System (ADS)

    Trayanova, Natalia; Eason, James

    2002-09-01

    The focus of this article is the investigation of the electrical behavior of the normal myocardium following the delivery of high-strength defibrillation shocks. To achieve its goal, the study employs a complex three-dimensional defibrillation model of a slice of the canine heart characterized with realistic geometry and fiber architecture. Defibrillation shocks of various strengths and electrode configurations are delivered to the model preparation in which a sustained ventricular tachycardia is induced. Instead of analyzing the post-shock electrical events as progressions of transmembrane potential maps, the study examines the evolution of the postshock phase singularities (PSs) which represent the organizing centers of reentry. The simulation results demonstrate that the shock induces numerous PSs the majority of which vanish before the reentrant wavefronts associated with them complete half of a single rotation. Failed shocks are characterized with one or more PSs that survive the initial period of PS annihilation to establish a new postshock arrhythmia. The increase in shock strength results in an overall decrease of the number of PSs that survive over 200 ms after the end of the shock; however, the exact behavior of the PSs is strongly dependent on the shock electrode configuration.

  3. Post-shock relaxation in crystalline nitromethane

    NASA Astrophysics Data System (ADS)

    Rivera-Rivera, Luis A.; Sewell, Thomas D.; Thompson, Donald L.

    2013-02-01

    Molecular dynamics simulations of shocked (100)-oriented crystalline nitromethane were carried out to determine the rates of relaxation behind the shock wave. The forces were described by the fully flexible non-reactive Sorescu-Rice-Thompson force field [D. C. Sorescu, B. M. Rice, and D. L. Thompson, J. Phys. Chem. B 104, 8406 (2000)], 10.1021/jp000942q. The time scales for local and overall thermal equilibration in the shocked crystal were determined. The molecular center-of-mass and atomic kinetic energy distributions rapidly reach substantially different local temperatures. Several picoseconds are required for the two distributions to converge, corresponding to establishment of thermal equilibrium in the shocked crystal. The decrease of the molecular center-of-mass temperature and the increase of the atomic temperature behind the shock front exhibit essentially exponential dependence on time. Analysis of covalent bond distance distributions ahead of, immediately behind, and well behind the shock front showed that the effective bond stretching potentials are essentially harmonic. Effective force constants for the C-N, C-H, and N-O bonds immediately behind the shock front are larger by factors of 1.6, 2.5, and 2.0, respectively, than in the unshocked crystal; and by factors of 1.2, 2.2, and 1.7, respectively, compared to material sufficiently far behind the shock front to be essentially at thermal equilibrium.

  4. Heat Shock Proteins: Mediators of Atherosclerotic Development.

    PubMed

    Deniset, Justin F; Pierce, Grant N

    2015-01-01

    Heat shock proteins play important housekeeping roles in a variety of cells within the body during normal control conditions. The many different functions for heat shock proteins in the cell depend upon the specific heat shock protein involved. Each protein is nominally differentiated based upon its molecular size. However, in addition to their role in normal cell function, heat shock proteins may play an even more important role as pro-survival proteins conserved through evolution to protect the cell from a variety of stresses. The ability of a cell to withstand these environmental stresses is critical to its capacity to adapt and remain viable. Loss of this ability may lead to pathological states. Abnormal localization, structure or function of the heat shock proteins has been associated with many pathologies, including those involving heart disease. Heat shock proteins like HSP60 and HSP70 in particular have been identified as playing important roles in inflammation and immune reactions. Inflammation has been identified recently as an important pathological risk factor for heart disease. It is perhaps not surprising therefore, that heat shock protein family has been increasingly identified as an important intracellular pathway associated with inflammatory-mediated heart conditions including atherosclerosis. This paper reviews the evidence in support of a role for heat shock proteins in cardiovascular disease and the potential to target these proteins to alter the progression of atherosclerotic disease.

  5. Intense shock waves and shock-compressed gas flows in the channels of rail accelerators

    NASA Astrophysics Data System (ADS)

    Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.; Tverdokhlebov, K. V.

    2015-01-01

    Shock wave generation and shock-compressed gas flows attendant on the acceleration of an striker-free plasma piston in the channels of electromagnetic rail accelerators (railguns) are studied. Experiments are carried out in channels filled with helium or argon to an initial pressure of 25-500 Torr. At a pressure of 25 Torr, Mach numbers equal 32 in argon and 16 in helium. It is found that with the initial currents and gas initial densities in the channels being the same, the shock wave velocities in both gases almost coincide. Unlike standard shock tubes, a high electric field (up to 300 V/cm) present in the channel governs the motion of a shock-compressed layer. Once the charged particle concentration behind the shock wave becomes sufficiently high, the field causes part of the discharge current to pass through the shock-compressed layer. As a result, the glow of the layer becomes much more intense.

  6. Development of microcapsules for shock wave DDS and angiogenesis using shock waves

    NASA Astrophysics Data System (ADS)

    Tamagawa, M.; Yamanoi, I.; Iwakura, S.

    2006-05-01

    This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and angiogenesis using plane shock waves. We have proposed drug delivery systems (DDS) using shock waves. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young's modulus of capsule membrane, the membrane is deformed by the aspiration device and compared with computational result by FEM. As for angiogenesis using shock wave, the effects of shock waves under 0.4 MPa on cell growth rate is investigated. It is found that increasing rate of cell population by working shock waves is faster than the control cells.

  7. Whistler Waves Associated with Weak Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.

    2012-01-01

    We analyze the properties of 98 weak interplanetary shocks measured by the dual STEREO spacecraft over approximately 3 years during the past solar minimum. We study the occurrence of whistler waves associated with these shocks, which on average are high beta shocks (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the shocks. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost parallel to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the shock normal varies in a broad range of values (20 deg. to 90 deg.), suggesting that they are not phase standing. We find that the whistler waves can extend up to 100,000 km in the upstream region but in most cases (88%) are contained in a distance within 30,000 km from the shock. This corresponds to a larger region with upstream whistlers associated with IP shocks than previously reported in the literature. The maximum amplitudes of the waves are observed next to the shock interface, and they decrease as the distance to the shock increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the shock increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the shock. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the shock interface. In the downstream region, the waves are irregularly polarized, and the fluctuations are very compressive; that is, the compressive component of the wave clearly dominates over the transverse one. The majority of waves in the downstream region (95%) propagate at oblique angles with respect to the ambient magnetic field (>60 deg.). The wave propagation with respect to the shock-normal direction has no preferred direction and varies similarly to

  8. DNA fragmentation in mouse organs during endotoxic shock.

    PubMed Central

    Bohlinger, I.; Leist, M.; Gantner, F.; Angermüller, S.; Tiegs, G.; Wendel, A.

    1996-01-01

    The systemic inflammatory response syndrome has still an unpredictable outcome, and patients often die of multiple organ failure despite circulatory stabilization therapy. The still incompletely understood pathophysiological mechanisms include organ damage due to direct toxic actions of cytokines elicited by overactivation of the host response. To study this process of organ failure in experimental septic shock, we injected mice with a lethal dose of endotoxin and examined apoptotic and necrotic tissue damage biochemically, histologically, and ultrastructurally. Endotoxin administration caused oligonucleosomal as well as random DNA fragmentation in liver, lung, kidney, and intestine. In the liver, DNA fragmentation was not restricted to hepatocytes but also occurred in nonparenchymal cells. The DNA fragmentation was mediated by tumor necrosis factor and attenuated by endogenous nitric oxide release. Unlike the situation in D-galactosamine-sensitized mice, in which injection or release of tumor necrosis factor causes massive hepatocyte apoptosis, liver failure due to high doses of endotoxin was characterized by single-cell necrosis, a low incidence of apoptosis, and simultaneous damage to nonparenchymal cells. We conclude that, even though endotoxin causes cytokine-mediated DNA fragmentation in several organs including the liver, hepatocyte apoptosis itself seems to be a minor phenomenon in high-dose endotoxic shock in mice. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:8863685

  9. Physics of Bacteria During Osmotic Shock

    NASA Astrophysics Data System (ADS)

    Price, Jordan; Klug, William

    Bacteria combat hypoosmotic shocks by opening mechanosensitive ion channels located within the inner membrane. These channels are believed to act as ``emergency release valves,'' reducing transient pressure during the shock by regulating solute and water flux. Recent experiments have shown that cell survivability depends strongly on channel populations and the rate of osmotic shock. However, the understanding of the physical mechanisms behind osmotic protection remains unclear. We investigate how channel deletions, variations in shock rate, and cell envelope mechanics affect survivability by constructing theoretical elasticity and transport models. We find that reducing the number of channels and applying faster shocks significantly increases the time-dependent stress of the cell membrane and wall. This result provides insight into physical mechanisms that govern cell failure, including membrane rupture and wall fracture.

  10. Shock Timing Technique for the NIF

    SciTech Connect

    Munro, D.H.; Celliers, P.M.; Collins, G.W.; Gold, D.M.; DaSilva, L.B.; Haan, S.W.; Cauble, R.C.; Hammel, B.A.; Hsing, W.W.

    2000-10-03

    Among the final shots at the Nova laser was a series testing the VISAR technique that will be the primary diagnostic for timing the shocks in a NIF ignition capsule. At Nova, the VISAR technique worked over the range of shock strengths and with the precision required for the NIF shock timing job--shock velocities in liquid D{sub 2} from 12 {micro}m/ns to 65 {micro}m/ns with better than 2% accuracy. VISAR images showed stronger shocks overtaking weaker ones, which is the basis of the plan for setting the pulse shape for the NIF ignition campaign. The technique is so precise that VISAR measurements may also play a role in certifying beam-to-beam and shot-to-shot repeatability of NIF laser pulses.

  11. Classical MHD shocks: theory and numerical simulation

    SciTech Connect

    Pogorelov, Nikolai V.

    2005-08-01

    Recent results are surveyed in the investigation of the behavior of shocks in ideal magnetohydrodynamics (MHD) and corresponding structures in dissipative/resistive plasma flows. In contrast to evolutionary shocks, a solution of the problem of the nonevolutionary shock interaction with small perturbations is either nonunique or does not exist. The peculiarity of non-ideal MHD is in that some nonevolutionary shocks have dissipative structures. Since this structure is always non-plane, it can reveal itself in problems where transverse perturbations do not exist due to symmetries restrictions. We discuss the numerical behavior of nonevolutionary shocks and argue that they necessarily disappear once the problem is solved in a genuinely three-dimensional statement.

  12. Shock-produced olivine glass: First observation

    USGS Publications Warehouse

    Jeanloz, R.; Ahrens, T.J.; Lally, J.S.; Nord, G.L.; Christie, J.M.; Heuer, A.H.

    1977-01-01

    Transmission electron microscope (TEM) observations of an experimentally shock-deformed single crystal of natural peridot, (Mg0.88Fe 0.12SiO4 recovered from peak pressures of about 56 ?? 109 pascals revealed the presence of amorphous zones located within crystalline regions with a high density of tangled dislocations. This is the first reported observation ofolivine glass. The shocked sample exhibits a wide variation in the degree of shock deformation on a small scale, and the glass appears to be intimately associated with the highest density of dislocations. This study suggests that olivine glass may be formed as a result of shock at pressures above about 50 to 55 ?? 109 pascals and that further TEM observations of naturally shocked olivines may demonstrate the presence of glass.

  13. Barrier experiment: Shock initiation under complex loading

    SciTech Connect

    Menikoff, Ralph

    2016-01-12

    The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

  14. Probing shock models of CH(+) formation

    NASA Technical Reports Server (NTRS)

    Hawkins, Isabel; Craig, Nahide

    1991-01-01

    High-resolution, high SNR observations of CH and CH(+) toward Zeta Oph, Xi Per, and P Cyg are used to test several predictions of shock models of molecule formation. The predicted differences between the CH and HCH(+) heliocentric velocities of the magnitude produced by the shock theories are not found in any of the three stars. toward Zeta Oph and Xi Per, no difference is found, based on high-quality data, between the observed CH(+) lie profiles and a Gaussian function which would be expected as a result of shock structure. Gaussian line width parameters of CH(+) lines toward Zeta Oph and Xi Per are broad as predicted by shock models are consistent with previous measurements. These observations yield only weak evidence in favor of the predictions of shock models of molecule formation.

  15. Distant Bow Shock Observations by Explorer 33

    NASA Technical Reports Server (NTRS)

    Mihalov, J. D.

    1973-01-01

    Locations, orientations and magnetic field changes are given for 135 bow shock crossings at distances downstream from earth between 84 and 117 earth radii. The shock locations are dependent on the spacecraft trajectory and agree with locations calculated for the hypersonic analogue for a Mach number of 3.8. The shock normal vectors have been calculated using magnetic coplanarity. The average normal vectors have a greater inclination by approximately 17 + or - 5 deg from the symmetry axis than the Dryer and Heckman shock orientations for a 3.8 Mach number. Over a range of downstream distances from 60 to 115 earth radii, the median magnetic field magnitude jump across the shock changes from 1.90 to 1.70 times.

  16. Organic synthesis in experimental impact shocks

    NASA Technical Reports Server (NTRS)

    McKay, C. P.; Borucki, W. J.

    1997-01-01

    Laboratory simulations of shocks created with a high-energy laser demonstrate that the efficacy of organic production depends on the molecular, not just the elemental composition of the shocked gas. In a methane-rich mixture that simulates a low-temperature equilibrium mixture of cometary material, hydrogen cyanide and acetylene were produced with yields of 5 x 10(17) molecules per joule. Repeated shocking of the methane-rich mixture produced amine groups, suggesting the possible synthesis of amino acids. No organic molecules were produced in a carbon dioxide-rich mixture, which is at odds with thermodynamic equilibrium approaches to shock chemistry and has implications for the modeling of shock-produced organic molecules on early Earth.

  17. Shock-induced devolatilization of calcite

    NASA Technical Reports Server (NTRS)

    Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

    1982-01-01

    Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

  18. Lacticacidosis: A Clinically Significant Aspect of Shock

    PubMed Central

    Peretz, Dwight I.; McGregor, Maurice; Dossetor, John B.

    1964-01-01

    A study was made of the metabolic acidosis of hypotensive shock in 25 patients in an attempt to elucidate its etiology and to determine if the degree of acidosis might be a good parameter for the evaluation of treatment and prognosis. Blood lactate was elevated (> 1.3 mEq./l.) in 24 of 25 patients in hypotensive shock. There was a good correlation (r= 0.83, p < 0.01) between rising blood lactate and decrease in serum bicarbonate and arterial pH, early in shock. These data indicate that the metabolic acidosis of early shock is largely due to lactate ion. Evidence is presented that high blood lactate levels early in shock are indicative of poor prognosis. ImagesFig. 3 PMID:14127378

  19. Molecular shock response of explosives: electronic absorption spectroscopy

    SciTech Connect

    Mcgrne, Shawn D; Moore, David S; Whitley, Von H; Bolme, Cindy A; Eakins, Daniel E

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  20. Recognition and management of shock in the pediatric patient.

    PubMed

    Tuite, P K

    1997-05-01

    Shock continues to be a challenge for health care professionals because shock is not a single pathologic process but a complex series of interrelated events. After respiratory failure, shock is the second most common cause of death in children. The etiology of shock can be classified into three major categories: hypovolemic, cardiogenic, and distributive shock (septic shock). Despite the etiology of the shock state, if left untreated, the overwhelming response of the body to the inadequate perfusion is death. The key to successful management and treatment of shock is early recognition and rapid intervention.