Fatal head injury: a sequelae to electric shock - a case report.

Science.gov (United States)

Jayanth, S H; Hugar, Basappa S; Chandra, Y P Girish; Krishnan, A Gokula

2015-03-01

Deaths due to electric shock are increasing despite stringent laws and preventive measures. These shocks are a leading cause of death amongst construction workers. In about 20% of the cases, no visible injury due to electricity can be seen. In some cases, non-electrical injuries are present and at times there are no eyewitnesses to provide a detailed account of events. In such circumstances, examination of scene of death, autopsy and accident reconstruction with the help of an electrical expert are all necessary to determine the cause of death. Here, we report one such case where a mason working on the second floor of a building under construction sustained an electrical injury, following which he was thrown to the ground sustaining a fatal traumatic injury. After careful consideration, his death was attributed to the head injury. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Sensitivity towards fear of electric shock in passive threat situations.

Directory of Open Access Journals (Sweden)

Patrick Ring

Full Text Available Human judgment and decision-making (JDM requires an assessment of different choice options. While traditional theories of choice argue that cognitive processes are the main driver to reach a decision, growing evidence highlights the importance of emotion in decision-making. Following these findings, it appears relevant to understand how individuals asses the attractiveness or riskiness of a situation in terms of emotional processes. The following study aims at a better understanding of the psychophysiological mechanisms underlying threat sensitivity by measuring skin conductance responses (SCRs in passive threat situations. While previous studies demonstrate the role of magnitude on emotional body reactions preceding an outcome, this study focuses on probability. In order to analyze emotional body reactions preceding negative events with varying probability of occurrence, we have our participants play a two-stage card game. The first stage of the card game reveals the probability of receiving an unpleasant electric shock. The second stage applies the electric shock with the previously announced probability. For the analysis, we focus on the time interval between the first and second stage. We observe a linear relation between SCRs in anticipation of receiving an electric shock and shock probability. This finding indicates that SCRs are able to code the likelihood of negative events. We outline how this coding function of SCRs during the anticipation of negative events might add to an understanding of human JDM.

A simulation study of the reaction of human heart to biphasic electrical shocks

Directory of Open Access Journals (Sweden)

Seemann Gunnar

2004-06-01

Full Text Available Abstract Background This article presents a study, which examines the effects of biphasic electrical shocks on human ventricular tissue. The effects of this type of shock are not yet fully understood. Animal experiments showed the superiority of biphasic shocks over monophasic ones in defibrillation. A mathematical computer simulation can increase the knowledge of human heart behavior. Methods The research presented in this article was done with different models representing a three-dimensional wedge of ventricular myocardium. The electrophysiology was described with Priebe-Beuckelmann model. The realistic fiber twist, which is specific to human myocardium was included. Planar electrodes were placed at the ends of the longest side of the virtual cardiac wedge, in a bath medium. They were sources of electrical shocks, which varied in magnitude from 0.1 to 5 V. In a second arrangement ring electrodes were placed directly on myocardium for getting a better view on secondary electrical sources. The electrical reaction of the tissue was generated with a bidomain model. Results The reaction of the tissue to the electrical shock was specific to the initial imposed characteristics. Depolarization appeared in the first 5 ms in different locations. A further study of the cardiac tissue behavior revealed, which features influence the response of the considered muscle. It was shown that the time needed by the tissue to be totally depolarized is much shorter when a biphasic shock is applied. Each simulation ended only after complete repolarization was achieved. This created the possibility of gathering information from all states corresponding to one cycle of the cardiac rhythm. Conclusions The differences between the reaction of the homogeneous tissue and a tissue, which contains cleavage planes, reveals important aspects of superiority of biphasic pulses. ...

16 CFR 1204.4 - Electric shock protection tests.

Science.gov (United States)

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Electric shock protection tests. 1204.4 Section 1204.4 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT... the cable shall be between 28 and 29 feet (8.5 to 8.8 meters) above a horizontal plane through the...

Mortality and risk of cardiac complications among immediate survivors of accidental electric shock: a Danish nationwide cohort study.

Science.gov (United States)

Hansen, Steen Møller; Riahi, Sam; Hjortshøj, Søren; Mortensen, Rikke; Køber, Lars; Søgaard, Peter; Torp-Pedersen, Christian

2017-08-28

Exposure to electric shock has been associated with an increased risk of developing delayed cardiac arrhythmias and cardiac diseases. We examined whether electric shock patients have an increased risk of developing cardiac disease, cardiac arrhythmias or death compared with the general Danish population. Matched cohort study. A nationwide study in Denmark from 1994 to 2011. We identified 11 462 Danish patients who visited an emergency ward or were admitted to a hospital due to electric shock from 1994 to 2011. Each patient was matched for age and sex with five random controls from the Danish population. Mortality, cardiac procedures and cardiac diseases following electric shock. A total of 7390 electric shock patients were seen at an emergency ward and 4072 electric shock patients were admitted to a hospital. The median patient age was 28.6 years (Q1-Q3, 21.3-37.7) for the emergency ward patients and 26.4 years (Q1-Q3, 18.3-37.4) for admitted patients. In both groups, most patients were male (74.0% and 76.8%). Few of the electric shock patients had a record of cardiovascular disease at baseline (364/11 462, 3.2%). The 5-year cumulative incidence of death was 0.47% (95% CI 0.29% to 0.65%) for emergency ward patients and 1.04% (95% CI 0.71% to 1.37%) for admitted patients. No difference in 5-year survival was observed compared with matched controls (emergency ward, p=0.10; admitted patients, p=0.80). Fewer than four patients received a pacemaker within 30 days. This nationwide study did not demonstrate an increase in mortality among patients seen at hospitals after accidental electric shock compared with a background population. Cardiac procedures and diseases following electric shock were very rare. We suggest that nearly all patients can be discharged safely from the emergency room after electric shock without further observation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial

Shock to the system: Restructuring America's electricity industry

International Nuclear Information System (INIS)

Brennan, T.J.; Palmer, K.L.; Kopp, R.J.; Krupnick, A.J.; Stagliano, V.

1996-01-01

Recent decades have seen revolutions in communications, finance, and transportation. In a similar way, technological, economic, and political developments are reshaping the US electricity industry. This concise, balanced, and readable primer, produced by a team of economic analysts at Resources for the Future, introduces the concepts, crucial elements, and terminology used in discussions about electricity restructuring. A Shock to the System provides the background necessary to understand the increasing role of competition in electricity markets. The authors present the history of public policy regarding electricity, identify the significant proposals for implementing competition, and examine their potential consequences for utility regulation, industry structure, cost recovery, and the environment. This volume is an instructive guide to the decisions that electricity providers, customers, and policy makers will face, what forms the decisions are likely to take, and what the long-term ramifications may be

Shock waves in water at low energy pulsed electric discharges

International Nuclear Information System (INIS)

Pinchuk, M E; Kolikov, V A; Rutberg, Ph G; Leks, A G; Dolinovskaya, R V; Snetov, V N; Stogov, A Yu

2012-01-01

Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of ≤1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

Electrical conductivity measurements in shock compressed liquid nitrogen

International Nuclear Information System (INIS)

Hamilton, D.C.; Mitchell, A.C.; Nellis, W.J.

1985-06-01

The electrical conductivity of shock compressed liquid nitrogen was measured in the pressure range 20 to 50 GPa using a two-stage light-gas gun. The conductivities covered a range 4 x 10 -2 to 1 x 10 2 ohm -1 cm -1 . The data are discussed in terms of a liquid semiconductor model below the onset of the dissociative phase transition at 30 GPa. 15 refs., 1 fig

Schedules of electric shock presentation in the behavioral control of imprinted ducklings.

Science.gov (United States)

Barrett, J E

1972-09-01

The behavioral effects of various schedules of electric shock presentation were investigated during and after the imprinting of Peking ducklings to moving stimuli. The behavior of following a moving imprinted stimulus was differentially controlled by a multiple schedule of punishment and avoidance that respectively suppressed and maintained following behavior. Pole-pecking, reinforced by presentations of the imprinted stimulus, was suppressed by response-produced shock (punishment); various schedules of response-independent shock and delayed punishment had an overall minimal effect. The delivery of response-independent shock in the presence of one of two stimuli, both during and after imprinting, resulted in a marked reduction in choice of the stimulus paired with shock. The experiments provide no support for a differentiation of imprinting from learning on the basis of the behavioral effects of aversive stimuli. Instead, as is the case with other organisms, the schedule under which shock is delivered to imprinted ducklings appears to be an important determinant of the temporal patterning of subsequent behavior.

Experimental investigations on the anomaly of the electric conductivity in magnetohydrodynamic shock waves

International Nuclear Information System (INIS)

Zeyer, G.

1975-01-01

In the present work results of experimental investigations on the structure of resistive MHD shock waves are reported. The anomaly of the electric conductivity possibly occurring in such shock waves is an effect which has given new insight on the interaction mechanims of a plasma. In a modified Theta-Pinch setup deuterium plasma shock waves perpendicular to the magnetic field are studied with the aid of probes and scattering of laser light to determine the internal magnetic field and electron temperature and density. (GG) [de

Electric gun: a new method for generating shock pressures in excess of 1 TPa

International Nuclear Information System (INIS)

Steinberg, D.; Chau, H.; Dittbenner, G.; Weingart, R.

1978-01-01

By combining the electrically-driven, flying-plate, high-explosive initiator with well-known gas-gun technology, a novel method of generating and measuring shock pressures greater than 1 TPa has been developed. Called the electric gun, this system is competitive with laser or nuclear-driven, shock-wave, equation-of-state experiments in the 1 to 5 TPa range. Compared to those other methods, it has the advantage of simplicity, high precision, and low cost. In addition, its small size and low total energy allow it to be easily contained for experiments with toxic materials

Risk of neurological diseases among survivors of electric shocks

DEFF Research Database (Denmark)

Grell, Kathrine; Meersohn, Andrea; Schüz, Joachim

2012-01-01

Several studies suggest a link between electric injuries and neurological diseases, where electric shocks may explain elevated risks for neuronal degeneration and, subsequently, neurological diseases. We conducted a retrospective cohort study on the risk of neurological diseases among people...... in Denmark who had survived an electric accident in 1968-2008. The cohort included 3,133 people and occurrences of neurological diseases were determined by linkage to the nationwide population-based Danish National Register of Patients. The numbers of cases observed at first hospital contact in the cohort...... were compared with the respective rates of first hospital contacts for neurological diseases in the general population. We observed significantly increased risks for peripheral nerve diseases (standardized hospitalization ratio (SHR), 1.66; 95% confidence interval (CI), 1.22-2.22), for migraine (SHR, 1...

Effects of shock waves, ultraviolet light, and electric fields from pulsed discharges in water on inactivation of Escherichia coli.

Science.gov (United States)

Sun, Bing; Xin, Yanbin; Zhu, Xiaomei; Gao, Zhiying; Yan, Zhiyu; Ohshima, Takayuki

2018-04-01

In this work, the bacterial inactivation effects of shock waves, ultraviolet (UV) light, and electric field produced by high-voltage pulsed discharge in liquid with needle-plate configurations were studied. The contributions of each effect on the bacterial killing ratio in the discharge process were obtained individually by modifying reactor type and usage of glass, quartz, and black balloons. The results showed that the location from the discharge center axis significantly influenced the effects of shock waves and electric fields, although the effect of UV light was not affected by the location in the reactor. The effects of shock waves and electric fields were improved by decreasing the distance from the discharge center axis. Under this experimental condition, the effects of shock waves, UV light, and electric fields produced by discharges on bacterial inactivation were approximately 36.1%, 30.8%, 12.7%, respectively. Other contributions seemed to be due to activated species. Copyright © 2017 Elsevier B.V. All rights reserved.

A composite model for a class of electric-discharge shock tubes

Science.gov (United States)

Elkins, R. T.; Baganoff, D.

1973-01-01

A gasdynamic model is presented and analyzed for a class of shock tubes that utilize both Joule heating and electromagnetic forces to produce high-speed shock waves. The model consists of several stages of acceleration in which acceleration to sonic conditions is achieved principally through heating, and further acceleration of the supersonic flow is obtained principally through use of electromagnetic forces. The utility of the model results from the fact that it predicts a quasi-steady flow process, mathematical analysis is straightforward, and it is even possible to remove one or more component stages and still have the model related to a possible shock-tube flow. Initial experiments have been performed where the electrical discharge configuration and current level were such that Joule heating was the dominant form of energy addition present. These experiments indicate that the predictions of the model dealing with heat addition correspond quite closely to reality. The experimental data together with the theory show that heat addition to the flowing driver gas after diaphragm rupture (approach used in the model) is much more effective in producing high-speed shock waves than heating the gas in the driver before diaphragm rupture, as in the case of the arc-driven shock tube.

Digoxin Is Associated With Increased Shock Events and Electrical Storms in Patients With Implantable Cardioverter Defibrillators.

Science.gov (United States)

Mina, George S; Acharya, Madan; Shepherd, Taylor; Gobrial, George; Tekeste, Michael; Watti, Hussam; Bhandari, Ruchi; Saini, Aditya; Reddy, Pratap; Dominic, Paari

2018-03-01

Recently, digoxin use has been found to associate with higher mortality. Yet, potential mechanisms by which digoxin use increases mortality remain unclear. Increased arrhythmogenicity from digoxin use is one possibility. Thus, we aimed to evaluate the relation between digoxin and shock events in patients with implantable cardioverter defibrillators (ICDs). We performed a retrospective chart review of all patients with ICDs and at least 1 device interrogation at our institution between January 1, 2012, and January 1, 2015. We aimed to cover 1 year of interrogation period. Patients with heart failure, atrial fibrillation, or both were included in the analysis. Patients were divided into 2 groups based on digoxin use, defined as use of digoxin for any period of time during ICD interrogation period. Incidence of ICD shock events and electrical storms and hospitalizations were compared between the 2 groups. The study included 202 patients. Of those, 55 patients were on digoxin and 147 were not on digoxin. Patients on digoxin were more likely to receive ICD shocks (odds ratio [OR] = 2.5, 95% confidence interval [95% CI] = 1.01-6.18, P = .04) and have increased risk of electrical storms ( P = .02). Moreover, total hospitalizations were higher in digoxin users ( P = .02). Multivariate logistic regression analysis also showed that digoxin use was an independent predictor of shock events (OR = 4.07, 95% CI = 1.43-11.58, P = .009). Digoxin is associated with increased shock events and electrical storms in patients with ICDs; however, large randomized controlled studies are needed to confirm our findings.

Effect of Shock Waves Generated by Pulsed Electric Discharges in Water on Yeast Cells and Virus Particles

Science.gov (United States)

Girdyuk, A. E.; Gorshkov, A. N.; Egorov, V. V.; Kolikov, V. A.; Snetov, V. N.; Shneerson, G. A.

2018-02-01

The aim of this study is to determine the optimal parameters of the electric pulses and shock waves generated by them for the soft destruction of the virus and yeast envelopes with no changes in the structure of antigenic surface albumin and in the cell morphology in order to use them to produce antivirus vaccines and in biotechnology. The pulse electric discharges in water have been studied for different values of amplitude, pulse duration and the rate of the rise in the current. A mathematical model has been developed to estimate the optimal parameters of pulsed electric charges and shock waves for the complete destruction of the yeast cell envelopes and virus particles at a minimum of pulses.

Electrical conductivity of hydrogen shocked to megabar pressures

International Nuclear Information System (INIS)

Weir, S.T.; Nellis, W.J.; Mitchell, A.C.

1993-08-01

The properties of ultra-high pressure hydrogen have been the subject of much experimental and theoretical study. Of particular interest is the pressure-induced insulator-to-metal transition of hydrogen which, according to recent theoretical calculations, is predicted to occur by band-overlap in the pressure range of 1.5-3.0 Mbars on the zero temperature isotherm. Extremely high pressures are required for metallization since the low-pressure band gap is about 15 eV. Recent static-pressure diamond anvil cell experiments have searched for evidence of an insulator-to-metal transition, but no conclusive evidence for such a transition has yet been supplied. Providing conclusive evidence for hydrogen metallization is difficult because no technique has yet been developed for performing static high-pressure electrical conductivity experiments at megabar pressures. The authors report here on electrical conductivity experiments performed on H 2 and D 2 multi-shocked to megabar pressures. Electrical conductivities of dense fluid hydrogen at these pressures and temperatures reached are needed for calculations of the magnetic fields of Jupiter and Saturn, the magnetic fields being generated by convective dynamos of hot, dense, semiconducting fluid hydrogen. Also, since electrical conduction at the pressure-temperature conditions being studied is due to the thermal excitation of charge carriers across the electronic band gap, these experiments yield valuable information on the width of the band gap at high densities

Effect of transcutaneous electrical muscle stimulation on muscle volume in patients with septic shock

DEFF Research Database (Denmark)

Poulsen, Jesper Brøndum; Møller, Kirsten; Jensen, Claus V

2011-01-01

Objective: Intensive care unit admission is associated with muscle wasting and impaired physical function. We investigated the effect of early transcutaneous electrical muscle stimulation on quadriceps muscle volume in patients with septic shock. Design: Randomized interventional study using...

Treatment of enuresis risoria in children by self-administered electric and imaginary shock

NARCIS (Netherlands)

Elzinga-Plomp, A.; Boemers, T. M.; Messer, A. P.; Vijverberg, M. A.; de Jong, T. P.; van Gool, J. D.

1995-01-01

To treat enuresis risoria (giggle micturition) by a self-administered electric and imaginary shock and to evaluate the outcome after behavioural therapy. Six boys and three girls with enuresis risoria were evaluated and treated. The mean age at referral was 10.4 years (range 5.7-14.2). All children

Collisionless shock waves

International Nuclear Information System (INIS)

Sagdeev, R.Z.; Kennel, C.F.

1991-01-01

Collisionless shocks cannot occur naturally on the earth, because nearly all matter here consists of electrically neutral atoms and molecules. In space, however, high temperatures and ultraviolet radiation from hot stars decompose atoms into their constituent nuclei and electrons, producing a soup of electrically charged particles known as a plasma. Plasma physicists proposed that the collective electrical and magnetic properties of plasmas could produce interactions that take the place of collisions and permit shocks to form. In 1964 the theoretical work found its first experimental confirmation. Norman F. Ness and his colleagues at the Goddard Space Flight Center, using data collected from the iMP-1 spacecraft, detected clear signs that a collisionless shock exists where the solar wind encounters the earth's magnetic field. More recent research has demonstrated that collisionless shocks appear in a dazzling array of astronomical settings. For example, shocks have been found in the solar wind upstream (sunward) of all the planet and comets that have been visited by spacecraft. Violent flares on the sun generate shocks that propagate to the far reaches of the solar system; tremendous galactic outbursts create disruptions in the intergalactic medium that are trillions of times larger. In addition, many astrophysicists think that shocks from supernova explosions in our galaxy accelerate cosmic rays, a class of extraordinarily energetic elementary particles and atomic nuclei that rain down on the earth from all directions

The Basic Research for Pulverization of Rice Using Underwater Shock Wave by Electric Discharge

Directory of Open Access Journals (Sweden)

M Ide

2016-09-01

Full Text Available In recent years, the food self-support rate of Japan is 40%, and this value is the lowest level in major developed countries. This reason includes decreasing of diverting rice consumption in Japan and increasing abandonment of cultivation. Therefore, these problems are solved by using rice powder instead of expensive flour, and we manage to increase the food selfsupport rate. Previously, the rice powder is manufactured by two methods. One is dry type, and the other is wet type. The former is the method getting rice powder by running dried rice to rotating metal, and has a problem which that starch is damaged by heat when processing was performed. The latter is performed same method against wet rice, and has a problem which a large quantity of water is used. As a method to solve these problems, an underwater shock wave is used. Shock wave is the pressure wave which is over speed of sound by discharging high energy in short time. Propagating shock wave in water is underwater shock wave. The characters of underwater shock wave are long duration of shock wave because water density is uniform, water is low price and easy to get and not heat processing. Thinking of industrialization, the electric discharge is used as the generating source of underwater shock wave in the experiment. As the results, the efficiency of obtaining enough grain size, 100ìm, of rice powder was too bad only using the simple processing using underwater shock wave. Therefore, in Okinawa National College of Technology collaborating with us, obtaining rice powder with higher efficiency by using converged underwater shock wave is the goal of this research. In this research, the underwater shock wave with equal energy of the experimental device of underwater shock wave is measured by the optical observation. In addition, the appearance converging underwater shock wave is simulated by numerical analysis, and the pressure appreciation rate between the first wave and converged

Casebook on electric safety accidents

International Nuclear Information System (INIS)

1987-09-01

This book gives concentration on electric safety accidents in domestic and abroad, which introduces general electrical safety with property of electricity, safe equipment and maintenance and protection of electric shock. It lists the cases of accident caused of electricity in domestic like accident in power substation, utilization equipment, load system and another accident by electricity like death in electric shock another by electricity like death in electric shock in new building construction, the cases caused of electricity in abroad like damage in electric shock by high voltage electric transformer, electric shock in summer and earth fault accident by fault cooling tower.

Influence of water conductivity on shock waves generated by underwater electrical wire explosion

Science.gov (United States)

Liu, Ben; Wang, Deguo; Guo, Yanbao

2018-01-01

The new application of electrical explosion of wire (EEW) used in petroleum industry is to enhance oil recovery (EOR). Because of the complex environment underground, the effect of underground water conductivity on EEW should be considered. This work describes the effect of water conductivities on discharge current, voltage and shock waves. It was found that the effect of water conductivity contains two parts. One is the shunt effect of saline water, which can be considered as a parallel load with the copper wire between the electrodes connected to the discharge circuit. The peak pressure of shock waves are gradually decrease with the increase of water conductivity. The other is the current loss through saline water directly to the ground ends without flowing through the electrodes. The shunt effect is the main factor affecting the wire discharge process. As the charging voltage increased, the energy loss caused by these two parts are all reduced. These indicate that increasing the charging voltage to a certain value will increase the energy efficiency to generate a more powerful shock waves in conductive water.

Relationship between energy deposition and shock wave phenomenon in an underwater electrical wire explosion

Science.gov (United States)

Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Qiu, Aici; Ding, Weidong; Zhang, Yongmin

2017-09-01

An experimental study of pressure waves generated by an exploding copper wire in a water medium is performed. We examined the effects of energy deposited at different stages on the characteristics of the resulting shock waves. In the experiments, a microsecond time-scale pulsed current source was used to explode a 300-μm-diameter, 4-cm-long copper wire with initial stored energies ranging from 500 to 2700 J. Our experimental results indicated that the peak pressure (4.5-8.1 MPa) and energy (49-287 J) of the shock waves did not follow a simple relationship with any electrical parameters, such as peak voltage or deposited energy. Conversely, the impulse had a quasi-linear relationship with the parameter Π. We also found that the peak pressure was mainly influenced by the energy deposited before separation of the shock wave front and the discharge plasma channel (DPC). The decay time constant of the pressure waveform was affected by the energy injection after the separation. These phenomena clearly demonstrated that the deposited energy influenced the expansion of the DPC and affected the shock wave characteristics.

Anticipation of electric shocks modulates low beta power and event-related fields during memory encoding.

Science.gov (United States)

Bauch, Eva M; Bunzeck, Nico

2015-09-01

In humans, the temporal and oscillatory dynamics of pain anticipation and its effects on long-term memory are largely unknown. Here, we investigated this open question by using a previously established behavioral paradigm in combination with magnetoencephalography (MEG). Healthy human subjects encoded a series of scene images, which was combined with cues predicting an aversive electric shock with different probabilities (0.2, 0.5 or 0.8). After encoding, memory for the studied images was tested using a remember/know recognition task. Behaviorally, pain anticipation did not modulate recollection-based recognition memory per se, but interacted with the perceived unpleasantness of the electric shock [visual analogue scale rating from 1 (not unpleasant) to 10 (highly unpleasant)]. More precisely, the relationship between pain anticipation and recollection followed an inverted u-shaped function the more unpleasant the shocks were rated by a subject. At the physiological level, this quadratic effect was mimicked in the event-related magnetic fields associated with successful memory formation ('DM-effect') ∼450ms after image onset at left frontal sensors. Importantly, across all subjects, shock anticipation modulated oscillatory power in the low beta frequency range (13-20Hz) in a linear fashion at left temporal sensors. Taken together, our findings indicate that beta oscillations provide a generic mechanism underlying pain anticipation; the effect on subsequent long-term memory, on the other hand, is much more variable and depends on the level of individual pain perception. As such, our findings give new and important insights into how aversive motivational states can drive memory formation. Copyright © 2015 Elsevier Inc. All rights reserved.

The Effect of Shock Stress and Field Strength on Shock-Induced Depoling of Normally Poled PZT 95/5

International Nuclear Information System (INIS)

CHHABILDAS, LALIT C.; FURNISH, MICHAEL D.; MONTGOMERY, STEPHEN T.; SETCHELL, ROBERT E.

1999-01-01

Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field generated within the PZT sample was varied through the choice of external circuit resistance. Shock pressures were varied from 0.6 to 4.6 GPa, and peak electrical fields were varied from 0.2 to 37 kV/cm. For a 2.4 GPa shock and the lowest peak field, a nearly constant current governed simply by the remanent polarization and the shock velocity was recorded. Both decreasing the shock pressure and increasing the electrical field resulted in reduced current generation, indicating a retardation of the depoling kinetics

Shock Prevention

Science.gov (United States)

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.

Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

Science.gov (United States)

Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

2015-03-01

The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

Hydraulic shock absorbers

International Nuclear Information System (INIS)

Thatcher, G.; Davidson, D. F.

1984-01-01

A hydraulic shock absorber of the dash pot kind for use with electrically conducting liquid such as sodium, has magnet means for electro magnetically braking a stream of liquid discharged from the cylinder. The shock absorber finds use in a liquid metal cooled nuclear reactor for arresting control rods

Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

Science.gov (United States)

Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

1992-01-01

Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

Existence and Stability of Viscous Shock Profiles for 2-D Isentropic MHD with Infinite Electrical Resistivity

International Nuclear Information System (INIS)

Blake, B.; Zumbrun, K.; Lafitte, O.

2010-01-01

For the two-dimensional Navier Stokes equations of isentropic magnetohydrodynamics (MHD) with γ-law gas equation of state, γ≥1, and infinite electrical resistivity, we carry out a global analysis categorizing all possible viscous shock profiles. Precisely, we show that the phase portrait of the Crave ling-wave ODE generically consists of either two rest points connected by a viscous Lax profile, or else four rest points, two saddles and two nodes. In the latter configuration, which rest points are connected by profiles depends on the ratio of viscosities, and can involve Lax, over-compressive, or under-compressive shock profiles. Considered as three-dimensional solutions, under-compressive shocks are Lax-type (Alfven) waves. For the monatomic and diatomic cases γ=5/3 and γ=7/5, with standard viscosity ratio for a nonmagnetic gas, we find numerically that the the nodes are connected by a family of over-compressive profiles bounded by Lax profiles connecting saddles to nodes, with no under-compressive shocks occurring. We carry out a systematic numerical Evans function analysis indicating that all of these two-dimensional shock profiles are linearly and nonlinearly stable, both with respect to two- and three-dimensional perturbations. For the same gas constants, but different viscosity ratios, we investigate also cases for which under-compressive shocks appear; these are seen numerically to be stable as well, both with respect to two-dimensional and (in the neutral sense of convergence to nearby Riemann solutions) three-dimensional perturbations. (authors)

Control of adverse effects of explosive blasting in mines by using shock tube (non-electric) initiation systems and its future challenges

Energy Technology Data Exchange (ETDEWEB)

Sharma, P.D. [Maharashtra Explosives Ltd., Nagpur (India)

2000-04-01

Every kind of blasting in mines produces some adverse effects on environment, such as ground vibration, noise, fly rock etc. Presently, for restricting these adverse effects, use of shock tube (non-electric) initiation systems are gaining momentum. There are some inherent shortcomings of this initiation system regarding chances of misfires. This paper discusses the various adverse effects of blasting, advantages of shock tube initiation system and the shortcomings of shock tube initiation system regarding chances of misfire and how misfire arises out of failure of shock tube initiation system is different and more dangerous than the misfire occurring due to failure of conventional system (with detonating fuse and cord relays). 1 tab.

Unlimited Relativistic Shock Surfing Acceleration

International Nuclear Information System (INIS)

Ucer, D.; Shapiro, V. D.

2001-01-01

Nonrelativistic shock surfing acceleration at quasiperpendicular shocks is usually considered to be a preacceleration mechanism for slow pickup ions to initiate diffusive shock acceleration. In shock surfing, the particle accelerates along the shock front under the action of the convective electric field of the plasma flow. However, the particle also gains kinetic energy normal to the shock and eventually escapes downstream. We consider the case when ions are accelerated to relativistic velocities. In this case, the ions are likely to be trapped for infinitely long times, because the energy of bounce oscillations tends to decrease during acceleration. This suggests the possibility of unlimited acceleration by shock surfing

Resonant ion acceleration by collisionless magnetosonic shock waves

International Nuclear Information System (INIS)

Ohsawa, Y.

1985-01-01

Resonant ion acceleration ( the ν/sub rho/xΒ acceleration ) in laminar magnetosonic shock waves is studied by theory and simulation. Theoretical analysis based on a two-fluid model shows that, in laminar shocks, the electric field strength in the direction of the wave normal is about (m/sub i/m/sub e/) 1 2 times large for quasi-perpendicular shocks than that for the quasi-parallel shocks, which is a reflection of the fact that the width of quasi-perpendicular shocks is much smaller than that of the quasi-parallel shocks. Trapped ions can be accelerated up to the speed about ν/sub A/(m/sub i/m/sub e/) 1 2(M/sub A/-1) 3 2 in quasi-perpendicular shocks. Time evolution of self-consistent magnetosonic shock waves is studied by using a 2-12 dimensional fully relativistic, fully electromagnetic particle simulation with full ion and electron dynamics. Even a low-Mach-number shock wave can significantly accelerate trapped ions by the ν/sub rho/xΒ acceleration. The resonant ion acceleration occurs more strongly in quasi-perpendicular shocks, because the magnitude of this acceleration is proportional to the electric field strength

Drift mechanism for energetic charged particles at shocks

International Nuclear Information System (INIS)

Webb, G.M.; Axford, W.I.; Terasawa, T.

1983-01-01

The energy changes of energetic charged particles at a plane shock due to the so-called drift mechanism are analyzed by using the ''adiabatic treatment.'' The analysis shows that for a fast MHD shock, particles lose energy owing to acceleration (curvature) drift in the magnetic field at the shock with the drift velocity being antiparallel to the electric field, and they gain energy owing to gradient drift parallel to the electric field. It is shown that particles with pitch angles aligned along the magnetic field which pass through the shock tend to lose energy owing to acceleration drift, whereas particles with pitch angles nonaligned to the magnetic field gain energy owing to gradient drift. Particles that are reflected by the shock always gain energy. Slow-mode shocks may be similarly analyzed, but in this case curvature drifts give rise to particle energy gains, and gradient drifts result in particle energy losses

Properties and structure of a plasma non-neutral shock

International Nuclear Information System (INIS)

Hu Yemin; Hu Xiwei

2004-01-01

The shock is described by the Navier-Stokes equations of the electron and ion fluids, and coupled with Poisson's equation for the self-induced electric field. Profiles of the flow and electric variables in the weak or moderate shock front with or without current for different Debye lengths are presented. Comparison of profiles of flow and electric variables in the front for different heat flow modes is given

INFLUENCE OF SHOCK VOLTAGE FROM THE ELECTRIC DISCHARGE ON THE FATIGUE ENDURANCE OF CARBON STEEL IN WATER

Directory of Open Access Journals (Sweden)

I. O. Vakulenko

2015-09-01

Full Text Available Purpose. The research supposes the explanation of influence of stress impulses from an electrical discharge in water on the level of the limited endurance at a cyclic loading of the thermally work-hardened carbon steel. Methodology. Material for research was steel 45 (0,45 % carbon with сoncentration of chemical elements within the limits of steel composition. Specimens for tests are made as plates in 1 thick, width 15 and length 120-180 mm. The structural state of steel corresponded to quenching on a martensite from the normal temperatures of annealing and tempering at 300C, duration of 1 h. Microstructure was investigated with the use of electronic microscopy, the density of dislocations was estimated on the methods of X-ray analysis. Hardness was measured on the method of Rockwell (scale of «C». A cyclic loading was carried out in the conditions of symmetric bend on a tester «Saturn-10» at a temperature +20C. The treatment by shock voltage from the electrical discharge was carried out in water on setting of bath type «Iskra-23», used for cleaning of castings manufactures. Electric impulses were formed at 15-18 kV with energy of 10-12 kJ and amplitude of 1-2 GPа. Findings. As a result of processing pulses of a pressure wave of heat-strengthened steel 45 found the increase of endurance under the cyclic loading corresponds to an increased amount of accumulated dislocations on the fracture surface. The use of Coffin–Manson Equation allowed finding the decrease of deformation per cycle of loading as a result of arising stress from an electrical discharge in water. On the fracture surface (after pulse exposure was found the increased number of dislocations, located in different crystallographic systems, that is a testament to the rather complicated development of dislocation transformations in the structure of steel, which provide an increase of endurance at a fatigue. The increase of the limited endurance became as a result of impulsive

Investigation of shock compressed plasma parameters by interaction with magnetic field

International Nuclear Information System (INIS)

Dudin, S. V.; Fortov, V. E.; Gryaznov, V. K.; Mintsev, V. B.; Shilkin, N. S.; Ushnurtsev, A. E.

1998-01-01

The Hall effect parameters in shock compressed air, helium and xenon have been estimated and results of experiments with air and helium plasma are presented. Explosively driven shock tubes were used for the generation of strong shock waves. To obtain magnetic field a solenoid was winded over the shock tube. Calculations of dense shock compressed plasma parameters were carried out to plan the experiments. In the experiments with the magnetic field of ∼5 T it was found, that air plasma slug was significantly heated by the whirlwind electrical field. The reflected shock waves technique was used in the experiments with helium. Results on measurements of electrical conductivity and electron concentration of helium are presented

Pick-up ion energization at the termination shock

Energy Technology Data Exchange (ETDEWEB)

Gary, S Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Wu, Pin [BOSTON UNIV.; Schwadron, N A [BOSTON UNIV.

2009-01-01

One-dimensional hybrid simulations are used to investigate how pickup ions are energized at the perpendicular termination shock. Contrary to previous models based on pickup ion energy gain by repeated crossings of the shock front (shock surfing) or due to a reforming shock front, the present simulations show that pickup ion energy gain involves a gyro-phasedependent interaction with the inhomogeneous motional electric field at the shock. The process operates at all relative concentrations of pickup ion density.

Investigations on GSK-3β/NF-kB signaling in stress and stress adaptive behavior in electric foot shock subjected mice.

Science.gov (United States)

Bali, Anjana; Jaggi, Amteshwar Singh

2016-04-01

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice. Copyright © 2016 Elsevier B.V. All rights reserved.

Adiabatic energy change of plasma electrons and the frame dependence of the cross-shock potential at collisionless magnetosonic shock waves

International Nuclear Information System (INIS)

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

1984-01-01

In collisionless magnetosonic shock waves, ions are commonly thought to be decelerated by dc electrostatic cross-shock electric field along the shock normal n. In a frame where ions are normally incident to the shock the change in the potential energy [qphi/sup N/] in the quasi-perpendicular geommetry is of the order of the change of the energy of normal ion flow: [qphi/sup N/]roughly-equal[1/2m/sub i/(V/sub i//sup N/xn) 2 ], which is approximately 200-500 eV at the earth's bow shock. We show that the electron energy gain, typically 1/10 this number, is consistent with such a large potential jump in this geometry. Key facts are the different paths taken by electrons an ions through the shock wave and the frame dependence of the potential jump in the geometry. In the normal incidence frame, electrons lose energy by doing work against the solar wind motional electric field E/sub M//sup N/, which partially offsets the energy gain from the cross-shock electrostatic potential energy [ephi/sub asterisk//sup N/]. In the de Hoffman-Teller frame the motional electric field vanishes; the elctrons gain the full electrostatic potential energy jump e[phi/sub asterisk//sup H//sup T/] of that frame, which is not, however, equal to the electrostatic potential energy jump e[phi/sub asterisk//sup N/] of that frame, which is not, however, equal to the electrostatic potential energy jump e[phi/sub asterisk//sup N/] in the normal incidence frame

Electricity your common sense guide

CERN Document Server

Ilich, Nick

2015-01-01

At last, a book that explains electricity in a very simple and easy way for everyone to understand. You will learn the basics of electricity, power to your home, receptacles, neutral and grounding, extension cord "Do's" and "Don'ts" and electrical shock.The book ends with safety tips and suggestions for you to stay safe and be shock free.

Comparison of the shock artifacts induced by tripolar and bipolar electrical stimulation techniques.

Science.gov (United States)

Wee, A S; Jiles, K; Brennan, R

2001-01-01

Tripolar and bipolar electrical stimulation procedures were performed on the upper limbs of eight subjects. The mid-forearm was stimulated electrically (tripolar or bipolar) by surface electrodes, and the induced stimulus shock artifacts were recorded simultaneously from the wrist and elbow. During tripolar stimulation, two types of stimulating configurations were utilized: with the center electrode designated as the cathode and the two outermost electrodes connected to a common anode, and vice versa. During bipolar stimulation, the center electrode served as one pole of the stimulator, and one of the two outermost electrodes of the tripolar stimulator was disconnected. The stimulus intensity was kept constant in all stimulating procedures. Artifacts were reduced significantly during tripolar compared to bipolar stimulation, if the outermost electrodes of the tripolar stimulator (which were facing the recording electrodes) were also oriented toward the recording sites during bipolar stimulation and had the same stimulus polarity. Artifacts were slightly reduced in amplitude from tripolar stimulation, if the center electrode were oriented toward the recording sites during bipolar stimulation and had the same stimulus polarity as previously used during tripolar stimulation.

Condensed matter at high shock pressures

International Nuclear Information System (INIS)

Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

1985-01-01

Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N 2 , CO, SiO 2 -aerogel, H 2 O, and C 6 H 6 . The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab

An Introduction to the Physics of Collisionless Shocks

International Nuclear Information System (INIS)

Russell, C.T.

2005-01-01

Collisionless shocks are important in astrophysical, heliospheric and magnetospheric settings. They deflect flows around obstacles; they heat the plasma, and they alter the properties of the flow as it intersects those obstacles. The physical processes occurring at collisionless shocks depend on the Mach number (strength) and beta (magnetic to thermal pressure) of the shocks and the direction of the magnetic field relative to the shock normal. Herein we review how the shock has been modeled in numerical simulations, the basic physical processes at work, including dissipation and thermalization, the electric potential drop at the shock, and the formation of the electron and ion foreshocks

Condensed matter at high shock pressures

Energy Technology Data Exchange (ETDEWEB)

Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

1985-07-12

Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N/sub 2/, CO, SiO/sub 2/-aerogel, H/sub 2/O, and C/sub 6/H/sub 6/. The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab.

Anterior wrist and medial malleolus as the novel sites of tissue selection: a retrospective study on electric shock death through the hand-to-foot circuit pathway.

Science.gov (United States)

Xu, Guangtao; Su, Ruibing; Lv, Junyao; Hu, Bo; Gu, Huan; Li, Xianxian; Gu, Jiang; Yu, Xiaojun

2017-05-01

Our previous work demonstrated that characteristic changes could occur in the anterior wrist and medial malleolus in electric deaths through the hand-to-foot electric circuit pathway in an electric shock rat model. However, whether the same phenomenon occurs in humans is unknown. The aim of the present retrospective study was to ascertain whether the anterior wrist and medial malleolus could also be selected as the promising and significant sites in electric death through the hand-to-foot circuit pathway. Nineteen human cases from the autopsy and one clinical survivor who sustained a severe electric shock through the hand-to-foot circuit pathway were analyzed. Additional ten autopsy patients who died from traffic accidents and sudden cardiac attacks were used as the control group. Histopathological changes in the soft tissues of the anterior wrist and medial malleolus in all autopsy patients, as well as the electric current pathway of the survivor, were observed. The results showed that the nuclear polarizations in the anterior wrist and medial malleolus soft tissues of the electric death were extremely noticeable as compared with the controls. The most severe electrical injury in the survivor occurred in the anterior wrist. These findings suggest that the soft tissues of the anterior wrist and/or the medial malleolus as the narrowest parts of the limbs could be used as the complementary sites for tissue selection and considered as necessary locations for examinations to assess the electric death in medicolegal identification.

Two dimensional hybrid simulation of a curved bow shock

International Nuclear Information System (INIS)

Thomas, V.A.; Winske, D.

1990-01-01

Results are presented from two dimensional hybrid simulations of curved collisionless supercritical shocks, retaining both quasi-perpendicular and quasi-parallel sections of the shock in order to study the character and origin of the foreshock ion population. The simulations demonstrate that the foreshock ion population is dominated by ions impinging upon the quasi-parallel side of the shock, while nonlocal transport from the quasi-perpendicular side of the shock into the foreshock region is minimal. Further, it is shown that the ions gain energy by drifting significantly in the direction of the convection electric field through multiple shock encounters

Electron bulk acceleration and thermalization at Earth's quasi-perpendicular bow shock

Science.gov (United States)

Chen, L.-J.; Wang, S.; Wilson, L. B., III; Schwartz, S. J.; Bessho, N.; Moore, T. E.; Gershman, D. J.; Giles, B. L.; Malaspina, D. M.; Wilder, F. D.; Ergun, R. E.; Hesse, M.; Lai, H.; Russell, C. T.; Strangeway, R. J.; Torbert, R. B.; Vinas, A. F.-; Burch, J. L.; Lee, S.; Pollock, C.; Dorelli, J.; Paterson, W. R.; Ahmadi, N.; Goodrich, K. A.; Lavraud, B.; Le Contel, O.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Boardsen, S.; Wei, H.; Le, A.; Avanov, L. A.

2018-05-01

Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

Electron velocity distributions near collisionless shocks

International Nuclear Information System (INIS)

Feldman, W.C.

1984-01-01

Recent studies of the amount of electron heating and of the shapes of electron velocity distributions across shocks near the earth are reviewed. It is found that electron heating increases with increasing shock strength but is always less than the ion heating. The scale length of electron heating is also less than that for the ions. Electron velocity distributions show characteristic shapes which depend on the strength of the shocks. At the weaker shocks, electron heating is mostly perpendicular to the ambient magnetic field, bar B, and results in Gaussian-shaped velocity distributions at low-to-moderate energies. At the stronger shocks, parallel heating predominates resulting in flat-topped velocity distributions. A reasonable interpretation of these results indicates that at the weaker shocks electron heating is dominated by a tendency toward conservation of the magnetic moment. At the stronger fast-mode shocks, this heating is thought to be dominated by an acceleration parallel to bar B produced by the macroscopic shock electric field followed by beam driven plasma instabilities. Some contribution to the heating at the stronger shocks from conservation of the magnetic moment and cross-field current-driven instabilities cannot be ruled out. Although the heating at slow-mode shocks is also dominated by instabilities driven by magnetic field-aligned electron beams, their acceleration mechanism is not yet established

Electric response of Pb0.99[(Zr0.90Sn0.10)0.968Ti0.032]0.98Nb0.02O3 ceramics to the shock-wave-induced ferroelectric-to-antiferroelectric phase transition

International Nuclear Information System (INIS)

Jiang Dongdong; Zhang Na; Feng Yujun; Du Jinmei; Gu Yan

2012-01-01

Highlights: ► Shock wave induces the FE-to-AFE phase transition in PbNb(Zr,Sn,Ti)O 3 . ► Depoling current due to phase transition depends on shock pressure and load resistance. ► Shock pressure promotes the phase transition in short-circuit case. ► Increasing load resistance decreases the released charge. - Abstract: Shock-wave-enforced ferroelectric (FE)-to-antiferroelectric (AFE) phase transition releases a large electrical polarization, having application in pulse power technology. In the present work, the depoling currents under shock wave compression were investigated in Pb 0.99 [(Zr 0.90 Sn 0.10 ) 0.968 Ti 0.032 ] 0.98 Nb 0.02 O 3 (PZST) ceramics with composition close to the FE/AFE phase boundary. Shock wave was generated by gas-gun and propagated in a direction perpendicular to the remanent polarization. It was found that the shock pressure promoted the phase transition under the short-circuit condition. The shock pressure dependence of the released charge was associated with the evolution of FE-to-AFE phase transition. The onset of phase transition was about 0.40 GPa and complete transformation occurred at 1.23 GPa. However, the released charge decreased with increasing load resistance. The reason may be that the electric field suppresses the phase transition in uncompressed zone and/or shock induces conductivity in compressed zone. Results lay the foundation for application of PZST ceramics in shock-activated power supply.

Elimination of spiral waves in cardiac tissue by multiple electrical shocks

NARCIS (Netherlands)

Panfilov, A.V.; Müller, Stefan C.; Zykov, Vladimir S.; Keener, James P.

1999-01-01

We study numerically the elimination of a spiral wave in cardiac tissue by application of multiple shocks of external current. To account for the effect of shocks we apply a recently developed theory for the interaction of the external current with cardiac tissue. We compare two possible feedback

The theory of ionizing shock waves in a magnetic field

International Nuclear Information System (INIS)

Liberman, M.A.; Velikovich, A.L.

1981-01-01

The general theory of ionizing shock waves in a magnetic field is constructed. The theory takes into account precursor ionization of a neutral gas ahead of the shock wave front, caused by photo-ionization, as well as by the impact ionization with electrons accelerated by a transverse electric field induced by the shock front in the incident flow of a neutral gas. The concept of shock wave ionization stability, being basic in the theory of ionizing shock waves in a magnetic field, is introduced. The ionizing shock wave structures are shown to transform from the GD regime at a low shock velocity to the MHD regime at an enhanced intensity of the shock wave. The abruptness of such a transition is determined by precursor photo-ionization. (author)

Why is electricity consumption inconsistent with economic growth in China?

International Nuclear Information System (INIS)

Lin, Boqiang; Liu, Chang

2016-01-01

Studies have indicated that there exists a relatively stable and positive correlation between electricity consumption and economic growth and there should not be a large deviation between them. However, the deviation between electricity consumption and economic growth in China during the Asian Financial Crisis and Global Economic Crisis sparks intense debates. We attempt to explain the deviation from the perspective of inventory investment adjustment in the business cycle using the SVAR model in this paper. The results show that the effects of inventory investment adjustment shock and electricity consumption structure shock on the deviation are positive but tend to be negative for electricity efficiency shock. The results of historical decomposition of these shocks also show that the inventory investment adjustment shock is the main factor that influences the deviation during the Global Economic Crisis. Economic fluctuation in the short term can not change the economic development pattern and the characteristics of electricity demand. Once the economy returns to stable growth, the deviation between electricity consumption and economic growth will shrink and disappear soon. - Highlights: • We analyze the deviation between GDP and electricity consumption in business cycle. • The inventory investment adjustment mainly impacts the deviation in China. • Concentrated electricity consumption of heavy industry magnifies the deviation.

Collisionless shocks in space plasmas structure and accelerated particles

CERN Document Server

Burgess, David

2015-01-01

Shock waves are an important feature of solar system plasmas, from the solar corona out to the edge of the heliosphere. This engaging introduction to collisionless shocks in space plasmas presents a comprehensive review of the physics governing different types of shocks and processes of particle acceleration, from fundamental principles to current research. Motivated by observations of planetary bow shocks, interplanetary shocks and the solar wind termination shock, it emphasises the physical theory underlying these shock waves. Readers will develop an understanding of the complex interplay between particle dynamics and the electric and magnetic fields that explains the observations of in situ spacecraft. Written by renowned experts in the field, this up-to-date text is the ideal companion for both graduate students new to heliospheric physics and researchers in astrophysics who wish to apply the lessons of solar system shocks to different astrophysical environments.

A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

International Nuclear Information System (INIS)

Le Roux, J. A.; Webb, G. M.

2012-01-01

Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

Success and failure of the defibrillation shock: insights from a simulation study.

Science.gov (United States)

Skouibine, K; Trayanova, N; Moore, P

2000-07-01

This simulation study presents a further inquiry into the mechanisms by which a strong electric shock fails to halt life-threatening cardiac arrhythmias. The research uses a model of the defibrillation process that represents a sheet of myocardium as a bidomain. The tissue consists of nonuniformly curved fibers in which spiral wave reentry is initiated. Monophasic defibrillation shocks are delivered via two line electrodes that occupy opposite tissue boundaries. In some simulation experiments, the polarity of the shock is reversed. Electrical activity in the sheet is compared for failed and successful shocks under controlled conditions. The maps of transmembrane potential and activation times calculated during and after the shock demonstrate that weak shocks fail to terminate the reentrant activity via two major mechanisms. As compared with strong shocks, weak shocks result in (1) smaller extension of refractoriness in the areas depolarized by the shock, and (2) slower or incomplete activation of the excitable gap created by deexcitation of the negatively polarized areas. In its turn, mechanism 2 is associated with one or more of the following events: (a) lack of some break excitations, (b) latency in the occurrence of the break excitations, and (c) slower propagation through deexcited areas. Reversal of shock polarity results in a change of the extent of the regions of deexcitation, and thus, in a change in defibrillation threshold. The results of this study indicate the paramount importance of shock-induced deexcitation in both defibrillation and postshock arrhythmogenesis.

Plasma and energetic particle structure of a collisionless quasi-parallel shock

Science.gov (United States)

Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Smith, E. J.; Wenzel, K. P.; Reinhard, R.; Sanderson, T. R.; Feldman, W. C.; Parks, G. K.

1983-01-01

The quasi-parallel interplanetary shock of November 11-12, 1978 from both the collisionless shock and energetic particle points of view were studied using measurements of the interplanetary magnetic and electric fields, solar wind electrons, plasma and MHD waves, and intermediate and high energy ions obtained on ISEE-1, -2, and -3. The interplanetary environment through which the shock was propagating when it encountered the three spacecraft was characterized; the observations of this shock are documented and current theories of quasi-parallel shock structure and particle acceleration are tested. These observations tend to confirm present self consistent theories of first order Fermi acceleration by shocks and of collisionless shock dissipation involving firehouse instability.

Highly trabeculated structure of the human endocardium underlies asymmetrical response to low-energy monophasic shocks

Science.gov (United States)

Connolly, Adam; Robson, Matthew D.; Schneider, Jürgen; Burton, Rebecca; Plank, Gernot; Bishop, Martin J.

2017-09-01

Novel low-energy defibrillation therapies are thought to be driven by virtual-electrodes (VEs), due to the interaction of applied monophasic electric shocks with fine-scale anatomical structures within the heart. Significant inter-species differences in the cardiac (micro)-anatomy exist, however, particularly with respect to the degree of endocardial trabeculations, which may underlie important differences in response to low-energy defibrillation protocols. Understanding the interaction of monophasic electric fields with the specific human micro-anatomy is therefore imperative in facilitating the translation and optimisation of these promising experimental therapies to the clinic. In this study, we sought to investigate how electric fields from implanted devices interact with the highly trabeculated human endocardial surface to better understand shock success in order to help optimise future clinical protocols. A bi-ventricular human computational model was constructed from high resolution (350 μm) ex-vivo MR data, including anatomically accurate endocardial structures. Monophasic shocks were applied between a basal right ventricular catheter and an exterior ground. Shocks of varying strengths were applied with both anodal [positive right ventricle (RV) electrode] and cathodal (negative RV electrode) polarities at different states of tissue refractoriness and during induced arrhythmias. Anodal shocks induced isolated positive VEs at the distal side of "detached" trabeculations, which rapidly spread into hyperpolarised tissue on the surrounding endocardial surfaces following the shock. Anodal shocks thus depolarised more tissue 10 ms after the shock than cathodal shocks where the propagation of activation from VEs induced on the proximal side of "detached" trabeculations was prevented due to refractory endocardium. Anodal shocks increased arrhythmia complexity more than cathodal shocks during failed anti-arrhythmia shocks. In conclusion, multiple detached

Dominant acceleration processes of ambient energetic protons (E>= 50 keV) at the bow shock: conditions and limitations

International Nuclear Information System (INIS)

Anagnostopoulos, G.C.; Sarris, E.T.

1983-01-01

Energetic proton (Esub(p)>= 50 keV) and magnetic field observations during crossings of the Earth's Bow Shock by the IMP-7 and 8 spacecraft are incorporated in this work in order to examine the effect of the Bow Shock on a pre-existing proton population under different ''interplanetary magnetic field-Bow Shock'' configurations, as well as the conditions for the presence of the Bow Shock associated energetic proton intensity enhancements. The presented observations indicate that the dominant process for the efficient acceleration of ambient energetic particles to energies exceeding approximately 50 keV is by ''gradient-B'' drifting parallel to the induced electric field at quasi-perpendicular Bow Shocks under certain well defined limitations deriving from the finite and curved Bow Shock surface. It is shown that the proton acceleration at the Bow Shock is most efficient for high values of the upstream magnetic field (in general B 1 > 8#betta#), high upstream plasma speed and expanded Bow Shock fronts, as well as for direction of the induced electric field oriented almost parallel to the flanks of the Bow Shock, i.e. when the drift distance of protons parallel to the electric field at the shock front is considerably smaller than the local radius of curvature of the Bow Shock. The implications of the presented observations of Bow Shock crossings as to the source of the energetic proton intensity enhancements are discussed. (author)

Energy-harvesting shock absorber with a mechanical motion rectifier

Science.gov (United States)

Li, Zhongjie; Zuo, Lei; Kuang, Jian; Luhrs, George

2013-02-01

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.

Energy-harvesting shock absorber with a mechanical motion rectifier

International Nuclear Information System (INIS)

Li, Zhongjie; Zuo, Lei; Kuang, Jian; Luhrs, George

2013-01-01

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges. (paper)

Biological effects of tandem shock waves demonstrated on magnetic resonance

Czech Academy of Sciences Publication Activity Database

Beneš, J.; Zeman, J.; Poučková, P.; Zadinová, M.; Šunka, Pavel; Lukeš, Petr

Roč. 113, č. 6 ( 2012 ), s. 335-338 ISSN 0006-9248 R&D Projects: GA ČR GA202/09/1151 Institutional research plan: CEZ:AV0Z20430508 Keywords : electrical discharges in water * focused shock waves * cavitations * tandem shock waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.472, year: 2012

Internal defibrillation: pain perception of low energy shocks.

Science.gov (United States)

Steinhaus, David M; Cardinal, Debbie S; Mongeon, Luc; Musley, Shailesh Kumar; Foley, Laura; Corrigan, Susie

2002-07-01

Recently, device-based low energy cardoversion shocks have been used as therapy for AF. However, discomfort from internal low energy electrical shocks is poorly understood. The aim of this study was to evaluate pain perception with low energy internal discharges. Eighteen patients with ICD devices for malignant ventricular arrhythmias were recruited to receive shocks of 0.4 and 2 J in the nonsedated state. Discharges were delivered in a blinded, random order and questionnaires were used to determine discomfort levels and tolerability. Patients perceived discharges at these energies as relatively uncomfortable, averaging a score of 7.3 on a discomfort scale of 0-10, and could not distinguish 0.4-J shocks from 2-J shocks. Second shocks were perceived as more uncomfortable than initial discharges, regardless of the order in which the shocks were delivered. Despite the perceived discomfort, 83% of patients stated that they would tolerate discharges of this magnitude once per month, and 44% would tolerate weekly discharges. Patients perceive low energy discharges as painful and cannot distinguish between shocks of 0.4 and 2 J. The results suggest that ICD systems developed to treat atrial tachyarrhythmias should minimize the number of shocks delivered to terminate an atrial tachyarrhythmia episode. The majority of the patients tolerated low energy shocks provided the discharges are infrequent (once per month).

Dissipation Mechanisms and Particle Acceleration at the Earth's Bow Shock

Science.gov (United States)

Desai, M. I.; Burch, J. L.; Broll, J. M.; Genestreti, K.; Torbert, R. B.; Ergun, R.; Wei, H.; Giles, B. L.; Russell, C. T.; Phan, T.; Chen, L. J.; Lai, H.; Wang, S.; Schwartz, S. J.; Allen, R. C.; Mauk, B.; Gingell, I.

2017-12-01

NASA's Magnetospheric Multiscale (MMS) mission has four spacecraft equipped with identical state-of-the-art instruments that acquire magnetic and electric field, plasma wave, and particle data at unprecedented temporal resolution to study the fundamental physics of magnetic reconnection in the Earth's magnetosphere. During Phase 1a, MMS also encountered and crossed the Earth's bow shock more than 300 times. We use burst data during 2 bow shock crossings to shed new light on key open questions regarding the formation, evolution, and dissipation mechanisms at collisionless shocks. Specifically, we focus on two events that exhibit clear differences in the ion and electron properties, the associated wave activity, and, therefore in the nature of the dissipation. In the case of a quasi-perpendicular, low beta shock crossing, we find that the dissipation processes are most likely associated with field-aligned electron beams that are coincident with high frequency electrostatic waves. On the other hand, the dissipation processes at an oblique, high beta shock crossing are largely governed by the quasi-static electric field and generation of magnetosonic whistler waves that result in perpendicular temperature anisotropy for the electrons. We also discuss the implications of these results for ion heating, reflection, and particle acceleration.

MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS

Directory of Open Access Journals (Sweden)

Mario Dobrilović

2005-12-01

Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.

Shock wave convergence in water with parabolic wall boundaries

International Nuclear Information System (INIS)

Yanuka, D.; Shafer, D.; Krasik, Ya.

2015-01-01

The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ∼45 kA and rise time of ∼80 ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger

Langmuir waveforms at interplanetary shocks: STEREO statistical analysis

Science.gov (United States)

Briand, C.

2016-12-01

Wave-particle interactions and particle acceleration are the two main processes allowing energy dissipation at non collisional shocks. Ion acceleration has been deeply studied for many years, also for their central role in the shock front reformation. Electron dynamics is also important in the shock dynamics through the instabilities they can generate which may impact the ion dynamics.Particle measurements can be efficiently completed by wave measurements to determine the characteristics of the electron beams and study the turbulence of the medium. Electric waveforms obtained from the S/WAVES instrument of the STEREO mission between 2007 to 2014 are analyzed. Thus, clear signature of Langmuir waves are observed on 41 interplanetary shocks. These data enable a statistical analysis and to deduce some characteristics of the electron dynamics on different shocks sources (SIR or ICME) and types (quasi-perpendicular or quasi-parallel). The conversion process between electrostatic to electromagnetic waves has also been tested in several cases.

Thermal burn and electrical injuries among electric utility workers, 1995-2004.

Science.gov (United States)

Fordyce, Tiffani A; Kelsh, Michael; Lu, Elizabeth T; Sahl, Jack D; Yager, Janice W

2007-03-01

This study describes the occurrence of work-related injuries from thermal-, electrical- and chemical-burns among electric utility workers. We describe injury trends by occupation, body part injured, age, sex, and circumstances surrounding the injury. This analysis includes all thermal, electric, and chemical injuries included in the Electric Power Research Institute (EPRI) Occupational Health and Safety Database (OHSD). There were a total of 872 thermal burn and electric shock injuries representing 3.7% of all injuries, but accounting for nearly 13% of all medical claim costs, second only to the medical costs associated with sprain- and strain-related injuries (38% of all injuries). The majority of burns involved less than 1 day off of work. The head, hands, and other upper extremities were the body parts most frequently injured by burns or electric shocks. For this industry, electric-related burns accounted for the largest percentage of burn injuries, 399 injuries (45.8%), followed by thermal/heat burns, 345 injuries (39.6%), and chemical burns, 51 injuries (5.8%). These injuries also represented a disproportionate number of fatalities; of the 24 deaths recorded in the database, contact with electric current or with temperature extremes was the source of seven of the fatalities. High-risk occupations included welders, line workers, electricians, meter readers, mechanics, maintenance workers, and plant and equipment operators.

Measurement of Radiative Non-Equilibrium for Air Shocks Between 7-9 Km/s

Science.gov (United States)

Cruden, Brett A.; Brandis, Aaron M.

2016-01-01

This paper describes a recent characterization of non-equilibrium radiation for shock speeds between 7 and 9 km/s in the NASA Ames Electric Arc Shock Tube (EAST) Facility. Data is spectrally resolved from 190- 1450 nm and spatially resolved behind the shock front. Comparisons are made to DPLR/NEQAIR simulations using different modeling options and recommendations for future study are made based on these comparisons.

Electrostatic and electromagnetic turbulence associated with the Earth's bow shock

International Nuclear Information System (INIS)

Rodriguez, P.

1974-01-01

The electric and magnetic field spectral densities of plasma waves in the earth's bow shock have been measured in the frequency range 20 Hz to 200 kHz using two 16-channel spectrum analyzers on the IMP-6 spacecraft. Electrostatic noise with a spectrum similar to the turbulence in the shock, but with lower intensities, is observed throughout the magnetosheath region, downstream of the shock. The intensity of the electrostatic component of turbulence in the bow shock increases as the upstream electron to ion temperature ratio increases, and decreases as the upstream sound velocity increases; both of these variations for the electrostatic component are consistent with ion sound wave turbulence. (U.S.)

Microgravity Experiment: The Fate of Confined Shock Waves

Science.gov (United States)

Kobel, P.; Obreschkow, D.; Dorsaz, N.; de Bosset, A.; Farhat, M.

2007-11-01

Shockwave induced cavitation is a form of hydrodynamic cavitation generated by the interaction of shock waves with vapor nuclei and microscopic impurities. Both the shock waves and the induced cavitation are known as sources of erosion damage in hydraulic industrial systems and hence represent an important research topic in fluid dynamics. Here we present the first investigation of shock wave induced cavitation inside closed and isolated liquid volumes, which confine the shock wave by reflections and thereby promise a particularly strong coupling with cavitation. A microgravity platform (ESA, 42^nd parabolic flight campaign) was used to produce stable water drops with centimetric diameters. Inside these drops, a fast electrical discharge was generated to release a strong shock wave. This setting results in an amplified form of shockwave induced cavitation, visible in high-speed images as a transient haze of sub-millimetric bubbles synchronized with the shockwave radiation. A comparison between high-speed visualizations and 3D simulations of a shock front inside a liquid sphere reveals that focus zones within the drop lead to a significantly increased density of induced cavitation. Considering shock wave crossing and focusing may hence prove crucially useful to understand the important process of cavitation erosion.

The effect of Coriandrum sativum seed extract on the learning of newborn mice by electric shock: interaction with caffeine and diazepam

Directory of Open Access Journals (Sweden)

Seyed Sadegh Zargar-Nattaj

2011-01-01

Full Text Available Seyed Sadegh Zargar-Nattaj1, Pooya Tayyebi1, Vahid Zangoori1, Yasaman Moghadamnia4, Hasan Roodgari2, Seyed Gholamali Jorsaraei3, Ali Akbar Moghadamnia11Department of Pharmacology, 2Department of Medical Genetics, 3Department of Anatomical Sciences and Embryology, Babol University of Medical Sciences, Babol, Iran; 4Department of Physics, Alzzahra University, Tehran, IranAbstract: Coriander has been recommended for the relief of pain, anxiety, flatulence, and loss of appetite. In traditional medicine, it is believed that coriander can induce some degree of amnesia in a child when his/her mother uses coriander during the pregnancy. We evaluated the effect of Coriandrum sativum seed extract on learning in second-generation mice. Ethanolic extract (2% of coriander (100 mg/kg intraperitoneal was dissolved in sunflower oil (oil as a vehicle and injected into the control group mother mice during breastfeeding for 25 days at 5-day intervals. After feeding the newborn mice, their learning was evaluated using a step-through passive avoidance task with 0.4 mA electric shock for 2 or 4 seconds. While coriander extract showed a negative effect in the short term (1 hour after the training session, it potentiated the mice's learning in later assessments (24 hours post-training [P = 0.022] and 1 week post-training [P = 0.002] by a 4-second shock. Low-dose caffeine (25 mg/kg ip after training improved the learning after 1 hour (P = 0.024; while diazepam (1 mg/kg ip suppressed learning at all time points after the 4-second shock training (1 hour, P = 0.022; 24 hours, P = 0.002; and 1 week, P = 0.008. No modification in the pain threshold was elicited by electric stimuli both in coriander and control groups. In conclusion, coriander does not improve learning within a short period of time after training; however, learning after coriander administration can be improved in the long term.Keywords: Coriandrum sativum, caffeine, diazepam, learning, memory, step through

Species separation and kinetic effects in collisional plasma shocks

Energy Technology Data Exchange (ETDEWEB)

Bellei, C., E-mail: bellei1@llnl.gov; Wilks, S. C.; Amendt, P. A. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Rinderknecht, H.; Zylstra, A.; Rosenberg, M.; Sio, H.; Li, C. K.; Petrasso, R. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2014-05-15

The properties of collisional shock waves propagating in uniform plasmas are studied with ion-kinetic calculations, in both slab and spherical geometry and for the case of one and two ion species. Despite the presence of an electric field at the shock front—and in contrast to the case where an interface is initially present [C. Bellei et al., Phys. Plasmas 20, 044702 (2013)]—essentially no ion reflection at the shock front is observed due to collisions, with a probability of reflection ≲10{sup −4} for the cases presented. A kinetic two-ion-species spherical convergent shock is studied in detail and compared against an average-species calculation, confirming effects of species separation and differential heating of the ion species at the shock front. The effect of different ion temperatures on the DT and D{sup 3}He fusion reactivity is discussed in the fluid limit and is estimated to be moderately important.

Regime Jumps in Electricity Prices

NARCIS (Netherlands)

R. Huisman (Ronald); R.J. Mahieu (Ronald)

2001-01-01

textabstractElectricity prices are known to be very volatile and subject to frequent jumps due to system breakdown, demand shocks, and inelastic supply. As many international electricity markets are in some state of deregulation, more and more participants in these markets are exposed to these

Electric gun: a new tool for ultrahigh-pressure research

International Nuclear Information System (INIS)

Weingart, R.C.; Chau, H.H.; Goosman, D.R.; Hofer, W.W.; Honodel, C.A.; Lee, R.S.; Steinberg, D.J.; Stroud, J.R.

1979-01-01

We have developed a new tool for ultrahigh-pressure research at LLL. This system, which we call the electric gun, has already achieved thin flyer plate velocities in excess of 20 km/s and pressures of the order of 2 TPa in tantalum. We believe that the electric gun is competitive with laser- and nuclear-driven methods of producing shocks in the 1-to-5 TPa range because of its precision and ease and economy of operation. Its development is recommended for shock initiation studies, dry runs for Site 300 hydroshots, and as a shock wave generator for surface studies

Effects of Shock and Turbulence Properties on Electron Acceleration

Science.gov (United States)

Qin, G.; Kong, F.-J.; Zhang, L.-H.

2018-06-01

Using test particle simulations, we study electron acceleration at collisionless shocks with a two-component model turbulent magnetic field with slab component including dissipation range. We investigate the importance of the shock-normal angle θ Bn, magnetic turbulence level {(b/{B}0)}2, and shock thickness on the acceleration efficiency of electrons. It is shown that at perpendicular shocks the electron acceleration efficiency is enhanced with the decrease of {(b/{B}0)}2, and at {(b/{B}0)}2=0.01 the acceleration becomes significant due to a strong drift electric field with long time particles staying near the shock front for shock drift acceleration (SDA). In addition, at parallel shocks the electron acceleration efficiency is increasing with the increase of {(b/{B}0)}2, and at {(b/{B}0)}2=10.0 the acceleration is very strong due to sufficient pitch-angle scattering for first-order Fermi acceleration, as well as due to the large local component of the magnetic field perpendicular to the shock-normal angle for SDA. On the other hand, the high perpendicular shock acceleration with {(b/{B}0)}2=0.01 is stronger than the high parallel shock acceleration with {(b/{B}0)}2=10.0, the reason might be the assumption that SDA is more efficient than first-order Fermi acceleration. Furthermore, for oblique shocks, the acceleration efficiency is small no matter whether the turbulence level is low or high. Moreover, for the effect of shock thickness on electron acceleration at perpendicular shocks, we show that there exists the bendover thickness, L diff,b. The acceleration efficiency does not noticeably change if the shock thickness is much smaller than L diff,b. However, if the shock thickness is much larger than L diff,b, the acceleration efficiency starts to drop abruptly.

Can a low-carbon-energy transition be sustained in post-Fukushima Japan? Assessing the varying impacts of exogenous shocks

International Nuclear Information System (INIS)

Wakiyama, Takako; Zusman, Eric; Monogan, James E.

2014-01-01

In the aftermath of the Fukushima nuclear crisis, Japan began contemplating energy policy reforms that drew inspiration from low-carbon research. This article focuses on a question central to advancing low-carbon research in Japan and elsewhere: namely, how does an exogenous shock affect the onset, magnitude, and permanence of changes in electricity consumption? The article employs intervention analysis with an autoregressive moving average (ARMA) model to answer this question. The data analysis reveals that post-Fukushima electricity use underwent a sudden, significant, and sustained reduction across Japan. The shock not only affected the Tokyo Electric Power Company (TEPCO) coverage area but the more distant Kansai Electric Power Company (KEPCO) coverage area. Large electricity users responded with an immediate and significant reduction in electricity consumption that rebounded to below pre-crisis levels; households responded more gradually with no rebound. Two of the more interesting results from the data analysis – the persistence in reductions in the more distant KEPCO coverage area and the rebound among large users – are then explained with a review of survey data and policy trends. Overall the quantitative and qualitative evidence suggests that an exogenous shock may give rise to a reduction in electricity consumption but cannot sustain a low-carbon transition. - Highlights: • Contributing to the literature on low carbon transitions. • Comparing post-Fukushima electricity consumption across regions and user groups. • Recommending reforms to sustain energy savings after an exogenous shock

Advances in ferroelectric polymers for shock compression sensors

International Nuclear Information System (INIS)

Bauer, F.; Moulard, H.; Samara, G.

1997-01-01

Our studies of the shock compression response of PVDF polymer are continuing in order to understand the physical properties under shock loading and to develop high fidelity, reproducible, time-resolved dynamic stress gauges. New PVDF technology, new electrode configurations and piezoelectric analysis have resulted in enhanced precision gauges. Our new standard gauges have a precision of better than 1% in electric charge release under shock up to 15 GPa. The piezoelectric response of shock compressed PVDF gauges 1 mm 2 in active area has been studied and yielded well-behaved reproducible data up to 20 GPa. Analysis of the response of these gauges in the open-quotes thin mode regimeclose quotes using a Lagrangian hydrocode will be presented. P(VDF-TrFE) copolymers exhibit unique piezoelectric properties over a wide range of temperature depending on the composition. Their properties and phase transitions are being investigated. Emphasis of the presentation will be on key results and implications

Sub-Saharan Africa Electricity Supply Inadequacy: Implications ...

African Journals Online (AJOL)

Africa has many electricity supply problems with major causes being natural causes (drought), oil price shock, system disruption by conflict, and low investment in electricity generation. To solve the problem, many countries adopted several reforms. However, the reforms failed to bring solutions. Electricity sector privatisation ...

Electron velocity distributions near the earth's bow shock

International Nuclear Information System (INIS)

Feldman, W.C.; Anderson, R.C.; Bame, S.J.; Gary, S.P.; Gosling, J.T.; McComas, D.J.; Thomsen, M.F.; Paschmann, G.; Hoppe, M.M.

1983-01-01

A survey of two-dimensional electron velocity distributions, f(V), measured near the earth's bow shock using Los Alamos/Garching plasma instrumentation aboard ISEE 2 is presented. This survey provides clues to the mechanisms of electron thermalization within the shock and the relaxation of both the upsteam and downstream velocity distributions. First, near the foreshock boundary, fluxes of electrons having a power law shape at high energies backstream from the shock. Second, within the shock, cuts through f(V) along B. f(V), often show single maxima offset toward the magnetosheath by speeds comparable to, but larger than, the upstream thermal speed.Third, magnetosheath distributions generally have flat tops out to an energy, E 0 , with maxima substantially lower than that in the solar wind. Occasionally, cuts through f(V) along B show one and sometimes two small peaks at the edge of the flat tops making them appear concave upward. The electron distributions characteristic of these three regions are interpreted as arising from the effects of macroscopic (scale size comparable to or larger than the shock width) electric and magnetic fields and the subsequent effects of microscopic (scale size small in comparison with the shock width) fields. In particular, our results suggest that field-aligned instabilities are likely to be present in the earth's bow shock

Electricity remains a serious workplace hazard.

Science.gov (United States)

Proctor, Laura; Kuchibotla, Srin

2013-08-01

Anyone who works in an industrial environment or is employed in the utility, mass transit, industrial goods manufacturing, or telecommunications industry - as well as many others - may be at risk for electrocution. Electric shock costs workers' lives and results in painful and debilitating injuries every year. Lockout/tagout procedures protect against electrocution, as do rubber insulating gloves, which must be worn any time workers are exposed to energized parts operating at 50 volts or higher. Some newer styles of rubber insulating gloves not only protect against electric shock, but also offer the dexterity and flexibility workers need for hours of comfortable wear.

An empirical examination of restructured electricity prices

International Nuclear Information System (INIS)

Knittel, C.R.; Roberts, M.R.

2005-01-01

We present an empirical analysis of restructured electricity prices. We study the distributional and temporal properties of the price process in a non-parametric framework, after which we parametrically model the price process using several common asset price specifications from the asset-pricing literature, as well as several less conventional models motivated by the peculiarities of electricity prices. The findings reveal several characteristics unique to electricity prices including several deterministic components of the price series at different frequencies. An 'inverse leverage effect' is also found, where positive shocks to the price series result in larger increases in volatility than negative shocks. We find that forecasting performance in dramatically improved when we incorporate features of electricity prices not commonly modelled in other asset prices. Our findings have implications for how empiricists model electricity prices, as well as how theorists specify models of energy pricing. (author)

Measuring the flexoelectric coefficient of bulk barium titanate from a shock wave experiment

Science.gov (United States)

Hu, Taotao; Deng, Qian; Liang, Xu; Shen, Shengping

2017-08-01

In this paper, a phenomenon of polarization introduced by shock waves is experimentally studied. Although this phenomenon has been reported previously in the community of physics, this is the first time to link it to flexoelectricity, the coupling between electric polarization and strain gradients in dielectrics. As the shock waves propagate in a dielectric material, electric polarization is thought to be induced by the strain gradient at the shock front. First, we control the first-order hydrogen gas gun to impact and generate shock waves in unpolarized bulk barium titanate (BT) samples. Then, a high-precision oscilloscope is used to measure the voltage generated by the flexoelectric effect. Based on experimental results, strain elastic wave theory, and flexoelectric theory, a longitudinal flexoelectric coefficient of the bulk BT sample is calculated to be μ 11 = 17.33 × 10 - 6 C/m, which is in accord with the published transverse flexoelectric coefficient. This method effectively suppresses the majority of drawbacks in the quasi-static and low frequency dynamic techniques and provides more reliable results of flexoelectric behaviors.

20000G shock energy harvesters for gun-fired munition

International Nuclear Information System (INIS)

Willemin, J.; Boisseau, S.; Olmos, L.; Gallardo, M.; Despesse, G.; Robert, T.

2016-01-01

This paper presents a 20000G shock energy harvester dedicated to gun-fired munitions and based on a mass-spring resonant structure coupled to a coil-magnet electromagnetic converter. The 20000G shock energy is firstly stored in the spring as elastic potential energy, released as mass-spring mechanical oscillations right after the shock and finally converted into electricity thanks to the coil-magnet transducer. The device has been modeled, sized to generate 200mJ in 150ms, manufactured and tested in a gun-fired munition. The prototype sizes 117cm 3 and weighs 370g. 210mJ have been generated in a test bench and 140mJ in real conditions; this corresponds to a mean output power of 0.93W (7.9mW/cm 3 ) and a maximum output power of 4.83W (41.3mW/cm 3 ) right after the shock. (paper)

20000G shock energy harvesters for gun-fired munition

Science.gov (United States)

Willemin, J.; Boisseau, S.; Olmos, L.; Gallardo, M.; Despesse, G.; Robert, T.

2016-11-01

This paper presents a 20000G shock energy harvester dedicated to gun-fired munitions and based on a mass-spring resonant structure coupled to a coil-magnet electromagnetic converter. The 20000G shock energy is firstly stored in the spring as elastic potential energy, released as mass-spring mechanical oscillations right after the shock and finally converted into electricity thanks to the coil-magnet transducer. The device has been modeled, sized to generate 200mJ in 150ms, manufactured and tested in a gun-fired munition. The prototype sizes 117cm3 and weighs 370g. 210mJ have been generated in a test bench and 140mJ in real conditions; this corresponds to a mean output power of 0.93W (7.9mW/cm3) and a maximum output power of 4.83W (41.3mW/cm3) right after the shock.

Shock wave compression and self-generated electric field repolarization in ferroelectric ceramics Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3

Science.gov (United States)

Jiang, Dongdong; Du, Jinmei; Gu, Yan; Feng, Yujun

2012-03-01

The shock wave induced depoling current of Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 ceramics was investigated with a system composed of a resistive load and an unpoled ceramic. Disparity in the depoling current was explained by considering the drawing charge effect of unpoled ceramic. The drawing effect for poled ceramics was analysed by developing a model incorporating a time- and electric-field-dependent repolarization. This model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. This work indicates that both the repolarization of uncompressed ceramics caused by the self-generated electric field and depolarization of compressed ceramics caused by the shock wave govern the output current.

Shock wave compression and self-generated electric field repolarization in ferroelectric ceramics Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3

International Nuclear Information System (INIS)

Jiang Dongdong; Du Jinmei; Gu Yan; Feng Yujun

2012-01-01

The shock wave induced depoling current of Pb 0.99 [(Zr 0.90 Sn 0.10 ) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics was investigated with a system composed of a resistive load and an unpoled ceramic. Disparity in the depoling current was explained by considering the drawing charge effect of unpoled ceramic. The drawing effect for poled ceramics was analysed by developing a model incorporating a time- and electric-field-dependent repolarization. This model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. This work indicates that both the repolarization of uncompressed ceramics caused by the self-generated electric field and depolarization of compressed ceramics caused by the shock wave govern the output current. (paper)

Fear conditioning and shock intensity: the choice between minimizing the stress induced and reducing the number of animals used

NARCIS (Netherlands)

Pietersen, C.Y.; Bosker, F.J; Posterna, F.; Den Boer, J.A.

2006-01-01

Many fear conditioning studies use electric shock as the aversive stimulus. The intensity of shocks varies throughout the literature. In this study, shock intensities ranging from 0 to 1.5 mA were used, and the effects on the rats assessed by both behavioural and biochemical stress parameters.

Fear conditioning and shock intensity : the choice between minimizing the stress induced and reducing the number of animals used

NARCIS (Netherlands)

Pietersen, CY; Bosker, FJ; Posterna, F; den Boer, JA

Many fear conditioning studies use electric shock as the aversive stimulus. The intensity of shocks varies throughout the literature. In this study, shock intensities ranging from 0 to 1.5 mA were used, and the effects on the rats assessed by both behavioural and biochemical stress parameters.

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

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

2016-01-01

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

Mostert, W.

2016-12-12

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Experimental Shock Damage Risk Assessment for New Generation TAS-B Plasmic Propulsion Unit

Science.gov (United States)

Garnier, J.; De Fruytier, C.

2014-06-01

This paper presents the methodology and the results of the shock test campaign conducted by TAS-B to qualify the PPU Mk2 unit in regards of increased shock levels.This unit supplies and controls two Plasma Thrusters used for satellite orbit keeping and attitude control. The PPU Mk2 unit mechanical design is based on a modular architecture. The different modules are mounted on a baseplate insuring thermal spreading and improved equipment flatness. The unit dimensions are 390 x 190 x 190 mm3 for a total mass of 11.5 kg.The PPU Mk2 contains several components sensitive to shock like specific inductors, transformers and relays. Due to an increasing of the shock specification in regards of the previous generation of PPU, it has been proposed to assess the good withstanding of these components and in order to mitigate the risks on the Qualification Model, a preliminary shock test has been performed on a Structural Model. This model is fully representative of the flight equipment in terms of mechanical interfaces and has been designed to have the same mechanical behaviour (same mass and main modes). Critical components have been embedded in this structural model in order to test their shock withstanding. Preliminary to this Structural Model, qualification at sensitive components levels has been performed through vibrations, shocks (half-sine) and thermal cycling. Evolution of the electrical main parameters has been followed to detect any degradation of the performance during this test campaigns.Then, the structural model has been instrumented to acquire the global behaviour of the equipment. Success criteria have been defined concerning mechanical behaviour before and after shocks, admissible electrical variations, visual inspections.After calibration phasis of the test bench, the shock test of the PPU Mk2 SM has been successfully conducted. The good test results allowed applying these shock levels confidently on the PPU Mk2 EQM model.

Nonstationarity of a two-dimensional quasiperpendicular supercritical collisionless shock by self-reformation

International Nuclear Information System (INIS)

Lembege, B.; Savoini, P.

1992-01-01

Two-dimensional electromagnetic particle simulations evidence a self-reformation of the shock front for a collisionless supercritical magnetosonic shock propagating at angle θ 0 around 90 degree, where θ 0 is the angle between the normal to the shock front and the upstream magnetostatic field. This self-reformation is due to reflected ions which accumulate in front of the shock and is observed (i) in both electric and magnetic components, (ii) for both resistive and nonresistive two-dimensional shocks, and (iii) over a cyclic time period equal to the mean ion gyroperiod measured downstream in the overshoot; resistive effects may be self-consistently included or excluded for θ 0 congruent 90 degree according to a judicious choice of the upstream magnetostatic field orientation. The self-reformation leads to a nonstationary behavior of the shock; however, present results show evidence that the shock becomes stationary for θ less than a critical value θ r , below which the self-reformation disappears. Present results are compared to previous works where one/two-dimensional hybrid and particle codes have been used, and to experimental measurements

Side-Pinch Effect of a Magnetically Driven Shock Tube with Parallel Plate Electrodes

DEFF Research Database (Denmark)

Chang, C. T.; Korsbech, Uffe C C; Mondrup, K.

1969-01-01

To study the possible effect of the side pinch on the steady-state current and the steady-state shock speed of a magnetically driven shock tube, a semiempirical model is formulated. The time history of the current, the radial and the translational motion of the current-carrying region are expressed...... by three interacting nonlinear equations with five adjustable parameters describing the variation of the electric circuit elements, the geometry of the shock tube, and the initial running conditions. Within the range of practical interest for values of the parameters investigated, computational results...

Kinetic Alfven waves and electron physics. II. Oblique slow shocks

International Nuclear Information System (INIS)

Yin, L.; Winske, D.; Daughton, W.

2007-01-01

One-dimensional (1D) particle-in-cell (PIC; kinetic ions and electrons) and hybrid (kinetic ions; adiabatic and massless fluid electrons) simulations of highly oblique slow shocks (θ Bn =84 deg. and β=0.1) [Yin et al., J. Geophys. Res., 110, A09217 (2005)] have shown that the dissipation from the ions is too weak to form a shock and that kinetic electron physics is required. The PIC simulations also showed that the downstream electron temperature becomes anisotropic (T e parallel )>T e perpendicular ), as observed in slow shocks in space. The electron anisotropy results, in part, from the electron acceleration/heating by parallel electric fields of obliquely propagating kinetic Alfven waves (KAWs) excited by ion-ion streaming, which cannot be modeled accurately in hybrid simulations. In the shock ramp, spiky structures occur in density and electron parallel temperature, where the ion parallel temperature decreases due to the reduction of the ion backstreaming speed. In this paper, KAW and electron physics in oblique slow shocks are further examined under lower electron beta conditions. It is found that as the electron beta is reduced, the resonant interaction between electrons and the wave parallel electric fields shifts to the tail of the electron velocity distribution, providing more efficient parallel heating. As a consequence, for β e =0.02, the electron physics is shown to influence the formation of a θ Bn =75 deg. shock. Electron effects are further enhanced at a more oblique shock angle (θ Bn =84 deg.) when both the growth rate and the range of unstable modes on the KAW branch increase. Small-scale electron and ion phase-space vortices in the shock ramp formed by electron-KAW interactions and the reduction of the ion backstreaming speed, respectively, are observed in the simulations and confirmed in homogeneous geometries in one and two spatial dimensions in the accompanying paper [Yin et al., Phys. Plasmas 14, 062104 (2007)]. Results from this study

Unexpected guest: Atrial fibrillation due to electrical shock

Directory of Open Access Journals (Sweden)

Mehmet Zihni Bilik

2016-03-01

Full Text Available Cardiac arrhythmias due to electrical injuries are rare among emergency service admittances. A 35 year-old female patient was admitted to emergency service with palpitation after electrical injury as a result of contact with a domestic low-voltage source. Electrocardiography (ECG showed atrial fibrillation with rapid ventricular response. Transthoracic echocardiography findings were normal. Atrial fibrillation spontaneously converted to normal sinus rhythm after rate limiting treatment with beta-blocker. The patient was discharged without any complication on the third day of hospitalization. Although cardiac arrhythmias rarely occur after electrical injury, cardiac monitoring is recommended for all patients with documented rhythm disorder, loss of consciousness, or abnormal ECG at admission.

A Comprehensive Review of the Techniques on Regenerative Shock Absorber Systems

Directory of Open Access Journals (Sweden)

Ran Zhang

2018-05-01

Full Text Available In this paper, the current technologies of the regenerative shock absorber systems have been categorized and evaluated. Three drive modes of the regenerative shock absorber systems, namely the direct drive mode, the indirect drive mode and hybrid drive mode are reviewed for their readiness to be implemented. The damping performances of the three different modes are listed and compared. Electrical circuit and control algorithms have also been evaluated to maximize the power output and to deliver the premium ride comfort and handling performance. Different types of parameterized road excitations have been applied to vehicle suspension systems to investigate the performance of the regenerative shock absorbers. The potential of incorporating nonlinearity into the regenerative shock absorber design analysis is discussed. The research gaps for the comparison of the different drive modes and the nonlinearity analysis of the regenerative shock absorbers are identified and, the corresponding research questions have been proposed for future work.

Impacts Of External Price Shocks On Malaysian Macro Economy-An Applied General Equilibrium Analysis

Directory of Open Access Journals (Sweden)

Abul Quasem Al-Amin

2008-10-01

Full Text Available This paper examines the impacts of external price shocks in the Malaysian economy. There are three simulations are carried out with different degrees of external shocks using Malaysian Social Accounting Matrix (SAM and Computable General Equilibrium (CGE analysis. The model results indicate that the import price shocks, better known as external price shocks by 15% decreases the domestic production of building and construction sector by 25.87%, hotels, restaurants and entertainment sector by 12.04%, industry sector by 12.02%, agriculture sector by 11.01%, and electricity and gas sector by 9.55% from the baseline. On the import side, our simulation results illustrate that as a result of the import price shocks by 15%, imports decreases significantly in all sectors from base level. Among the scenarios, the largest negative impacts goes on industry sectors by 29.67% followed by building and construction sector by 22.42%, hotels, restaurants and entertainment sector by 19.45%, electricity and gas sector by 13.%, agriculture sector by 12.63% and other service sectors by 11.17%. However significant negative impact goes to the investment and fixed capital investment. It also causes the household income, household consumption and household savings down and increases the cost of livings in the economy results in downward social welfare.

Pickup protons at quasi-perpendicular shocks: full particle electrodynamic simulations

Directory of Open Access Journals (Sweden)

S. Matsukiyo

2007-02-01

Full Text Available We have performed 3 one-dimensional full particle electromagnetic simulations of a quasi-perpendicular shock with the same Alfvén Mach number MA~5, shock normal-magnetic field angle ΘBn=87° and ion and electron beta (particle to magnetic field pressure of 0.1. In the first run we used an ion to electron mass ratio close to the physical one (mi/me=1024. As expected from previous high mass ratio simulations the Modified Two-Stream instability develops in the foot of the shock, and the shock periodically reforms itself. We have then self-consistently included in the simulation 10% pickup protons distributed on a shell in velocity space as a third component. In a run with an unrealistically low mass ratios of 200 the shock still reforms itself; reformation is due to accumulation of specularly reflected particles at the upstream edge of the foot. In a third run including pickup protons we used a mass ratio of 1024. The shock reforms periodically as in the low mass ratio run with a somewhat smaller time constant. The specular reflection of pickup protons results in an increase of the shock potential some distance ahead of the shock foot and ramp. The minimum scale of the cross shock potential during reformation is about 7 electron inertial length λe. We do not find any pickup proton acceleration in the ramp or downstream of the shock beyond the energy which specularly reflected ions gain by the motional electric field of the solar wind during their upstream gyration.

Massive electrical storm at disease onset in a patient with Brugada syndrome.

Science.gov (United States)

Pallisgaard, Jannik L; Gang, Uffe; Kanters, Jørgen K; Hansen, Peter R

2014-12-16

Brugada syndrome (BrS) is a genetic arrhythmogenic disease characterized by ST-segment elevations in the right precordial leads of the electrocardiogram (ECG). These ECG changes may be concealed and BrS may present with electrical storm characterized by recurrent ventricular tachycardia and fibrillation. A 49-year-old previously healthy man was admitted with electrical storm. The patient received direct current (DC) cardioversion shocks and only after intravenous lidocaine did the electrical storm slowly subside with a total of 255 DC shocks administered during the first 24 h after admission. He fully recovered and received an implantable cardioverter-defibrillator. Subsequent drug challenge with flecainide revealed type 1 BrS. Massive electrical storm can be the first symptom of BrS and the diagnostic ECG changes may be concealed at presentation. Although hundreds of DC shocks may be required during initial treatment, full recovery can be achieved.

Lower hybrid waves at the shock front: a reassessment

Directory of Open Access Journals (Sweden)

S. N. Walker

2008-03-01

Full Text Available The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (ω=Vik⊥ and magnetised electrons (ω=Vek||. In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.

Reversible electron heating vs. wave-particle interactions in quasi-perpendicular shocks

Science.gov (United States)

Veltri, P.; Mangeney, A.; Scudder, J. D.

1992-01-01

The energy necessary to explain the electron heating in quasi-perpendicular collisionless shocks can be derived either from the electron acceleration in the d.c. cross shock electric potential, or by the interactions between the electrons and the waves existing in the shock. A Monte Carlo simulation has been performed to study the electron distribution function evolution through the shock structure, with and without particle diffusion on waves. This simulation has allowed us to clarify the relative importance of the two possible energy sources; in particular it has been shown that the electron parallel temperature is determined by the d.c. electromagnetic field and not by any wave-particle-induced heating. Wave particle interactions are effective in smoothing out the large gradients in phase space produced by the 'reversible' motion of the electrons, thus producing a 'cooling' of the electrons.

Experiments on second-sound shock waves in superfluid helium

International Nuclear Information System (INIS)

Cummings, J.C.; Schmidt, D.W.; Wagner, W.J.

1978-01-01

The waveform and velocity of second-sound waves in superfluid helium have been studied experimentally using superconducting, thin-film probes. The second-sound waves were generated with electrical pulses through a resistive film. Variations in pulse power, pulse duration, and bath temperature were examined. As predicted theoretically, the formation of a shock was observed at the leading or trailing edge of the waves depending on bath temperature. Breakdown of the theoretical model was observed for large pulse powers. Accurate data for the acoustic second-sound speed were derived from the measurements of shock-wave velocities and are compared with previous results

Physics of Collisionless Shocks Space Plasma Shock Waves

CERN Document Server

Balogh, André

2013-01-01

The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

Electrostatic shock structures in dissipative multi-ion dusty plasmas

Science.gov (United States)

Elkamash, I. S.; Kourakis, I.

2018-06-01

A comprehensive analytical model is introduced for shock excitations in dusty bi-ion plasma mixtures, taking into account collisionality and kinematic (fluid) viscosity. A multicomponent plasma configuration is considered, consisting of positive ions, negative ions, electrons, and a massive charged component in the background (dust). The ionic dynamical scale is focused upon; thus, electrons are assumed to be thermalized, while the dust is stationary. A dissipative hybrid Korteweg-de Vries/Burgers equation is derived. An analytical solution is obtained, in the form of a shock structure (a step-shaped function for the electrostatic potential, or an electric field pulse) whose maximum amplitude in the far downstream region decays in time. The effect of relevant plasma configuration parameters, in addition to dissipation, is investigated. Our work extends earlier studies of ion-acoustic type shock waves in pure (two-component) bi-ion plasma mixtures.

Electricity conservation policies and sectorial output in Pakistan: An empirical analysis

International Nuclear Information System (INIS)

Mehmood Mirza, Faisal; Bergland, Olvar; Afzal, Naila

2014-01-01

Government of Pakistan has taken several measures in recent years for conserving electricity to reduce its electricity shortfall. In this context, this study attempts to quantify the impact of different electricity conservation policies on value-added of industrial and services sectors in Pakistan. Results indicate that unanticipated shocks to electricity consumption and technical efficiency form a positive relationship while electricity price has a negative relationship with value-added in industrial and services sectors in the long run. Direct electricity conservation policies and policies that aim at increasing electricity prices will have an adverse impact on value-added of both the sectors. Policies that induce improvements in energy efficiency will have a positive impact on the sectorial output in the long run. Therefore, the government should not pursue direct consumption curtailment polices to mitigate the electricity crisis rather steps should be taken to enhance energy efficiency in the economy. This can be done by setting targets for reducing energy intensity in both the sectors. Moreover, energy efficiency should be incorporated in the mainstream of energy policy and specific laws should be enacted to establish institutions and develop methods to help in effective conservation and efficient consumption of limited energy resources. - Highlights: • We quantify impact of electricity conservation policies on sectorial value added. • Shocks to electricity consumption and technical efficiency positively affect the output. • Shocks to electricity price negatively affects value-added in the long run. • Policies inducing improvements in energy efficiency positively affect the output

Pickup protons at quasi-perpendicular shocks: full particle electrodynamic simulations

Directory of Open Access Journals (Sweden)

S. Matsukiyo

2007-02-01

Full Text Available We have performed 3 one-dimensional full particle electromagnetic simulations of a quasi-perpendicular shock with the same Alfvén Mach number M_A~5, shock normal-magnetic field angle Θ_Bn=87° and ion and electron beta (particle to magnetic field pressure of 0.1. In the first run we used an ion to electron mass ratio close to the physical one (m_i/m_e=1024. As expected from previous high mass ratio simulations the Modified Two-Stream instability develops in the foot of the shock, and the shock periodically reforms itself. We have then self-consistently included in the simulation 10% pickup protons distributed on a shell in velocity space as a third component. In a run with an unrealistically low mass ratios of 200 the shock still reforms itself; reformation is due to accumulation of specularly reflected particles at the upstream edge of the foot. In a third run including pickup protons we used a mass ratio of 1024. The shock reforms periodically as in the low mass ratio run with a somewhat smaller time constant. The specular reflection of pickup protons results in an increase of the shock potential some distance ahead of the shock foot and ramp. The minimum scale of the cross shock potential during reformation is about 7 electron inertial length λ_e. We do not find any pickup proton acceleration in the ramp or downstream of the shock beyond the energy which specularly reflected ions gain by the motional electric field of the solar wind during their upstream gyration.

Measuring resilience to energy shocks

OpenAIRE

Molyneaux, Lynette; Brown, Colin; Foster, John; Wagner, Liam

2015-01-01

Measuring energy security or resilience in energy is, in the main, confined to indicators which are used for comparative purposes or to show trends rather than provide empirical evidence of resilience to unpredicted crises. In this paper, the electricity systems of the individual states within the United States of America are analysed for their response to the 1973-1982 and the 2003-2012 oil price shocks. Empirical evidence is sought for elements which are present in systems that experience r...

Electric Cars and Oil Prices

OpenAIRE

Azar, Jose

2009-01-01

This paper studies the joint dynamics of oil prices and interest in electric cars, measured as the volume of Google searches for related phrases. Not surprisingly, I find that oil price shocks predict increases in Google searches for electric cars. Much more surprisingly, I also find that an increase in Google searches predicts declines in oil prices. The high level of public interest in electric cars between April and August of 2008 can explain approximately half of the decline in oil prices...

Relativistic electron dropout echoes induced by interplanetary shocks

Science.gov (United States)

Schiller, Q.; Kanekal, S. G.; Boyd, A. J.; Baker, D. N.; Blake, J. B.; Spence, H. E.

2017-12-01

Interplanetary shocks that impact Earth's magnetosphere can produce immediate and dramatic responses in the trapped relativistic electron population. One well-studied response is a prompt injection capable of transporting relativistic electrons deep into the magnetosphere and accelerating them to multi-MeV energies. The converse effect, electron dropout echoes, are observations of a sudden dropout of electron fluxes observed after the interplanetary shock arrival. Like the injection echo signatures, dropout echoes can also show clear energy dispersion signals. They are of particular interest because they have only recently been observed and their causal mechanism is not well understood. In the analysis presented here, we show observations of electron drift echo signatures from the Relativistic Electron-Proton Telescope (REPT) and Magnetic Electron and Ion Sensors (MagEIS) onboard NASA's Van Allen Probes mission, which show simultaneous prompt enhancements and dropouts within minutes of the associated with shock impact. We show that the observations associated with both enhancements and dropouts are explained by the inward motion caused by the electric field impulse induced by the interplanetary shock, and either energization to cause the enhancement, or lack of a seed population to cause the dropout.

Oxidized Metal Powders for Mechanical Shock and Crush Safety Enhancers; TOPICAL

International Nuclear Information System (INIS)

GARINO, TERRY J.

2002-01-01

The use of oxidized metal powders in mechanical shock or crush safety enhancers in nuclear weapons has been investigated. The functioning of these devices is based on the remarkable electrical behavior of compacts of certain oxidized metal powders when subjected to compressive stress. For example, the low voltage resistivity of a compact of oxidized tantalum powder was found to decrease by over six orders of magnitude during compaction between 1 MPa, where the thin, insulating oxide coatings on the particles are intact, to 10 MPa, where the oxide coatings have broken down along a chain of particles spanning the electrodes. In this work, the behavior of tantalum and aluminum powders was investigated. The low voltage resistivity during compaction of powders oxidized under various conditions was measured and compared. In addition, the resistivity at higher voltages and the dielectric breakdown strength during compaction were also measured. A key finding was that significant changes in the electrical properties persist after the removal of the stress so that a mechanical shock enhancer is feasible. This was verified by preliminary shock experiments. Finally, conceptual designs for both types of enhancers are presented

Precise optical observation of 0.5-GPa shock waves in condensed materials

Science.gov (United States)

Nagayama, Kunihito; Mori, Yasuhito

1999-06-01

Precision optical observation method was developed to study impact-generated high-pressure shock waves in condensed materials. The present method makes it possible to sensitively detect the shock waves of the relatively low shock stress around 0.5 GPa. The principle of the present method is based on the use of total internal reflection by triangular prisms placed on the free surface of a target assembly. When a plane shock wave arrives at the free surface, the light reflected from the prisms extinguishes instantaneously. The reason is that the total internal reflection changes to the reflection depending on micron roughness of the free surface after the shock arrival. The shock arrival at the bottom face of the prisms can be detected here by two kinds of methods, i.e., a photographic method and a gauge method. The photographic method is an inclined prism method of using a high-speed streak camera. The shock velocity and the shock tilt angle can be estimated accurately from an obtained streak photograph. While in the gauge method, an in-material PVDF stress gauge is combined with an optical prism-pin. The PVDF gauge records electrically the stress profile behind the shockwave front, and the Hugoniot data can be precisely measured by combining the prism pin with the PVDF gauge.

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

Directory of Open Access Journals (Sweden)

V. V. Lobzin

2008-09-01

Full Text Available A new method for remote sensing of the quasiperpendicular part of the bow shock surface is presented. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock. Langmuir waves usually have maximum intensity at the upstream boundary of this region. All these waves are generated by energetic electrons accelerated by quasiperpendicular zone of the shock front. Nonstationary behavior of the shock, in particular due to rippling, should result in modulation of energetic electron fluxes, thereby giving rise to variations of Langmuir waves intensity. For upshifted and downshifted oscillations, the variations of both intensity and central frequency can be observed. For the present study, WHISPER measurements of electric field spectra obtained aboard Cluster spacecraft are used to choose 48 crossings of the electron foreshock boundary with dominating Langmuir waves and to perform for the first time a statistical analysis of nonstationary behavior of quasiperpendicular zone of the Earth's bow shock. Analysis of hidden periodicities in plasma wave energy reveals shock front nonstationarity in the frequency range 0.33 fBishock, and shows that the probability to observe such a nonstationarity increases with Mach number. The profiles observed aboard different spacecraft and the dominating frequencies of the periodicities are usually different. Hence nonstationarity and/or rippling seem to be rather irregular both in space and time rather than resembling a quasiregular wave propagating on the shock surface.

Simulations of Converging Shock Collisions for Shock Ignition

Science.gov (United States)

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.

A comparative study of plasma heating by ion acoustic and modified two-stream instabilities at subcritical quasi-perpendicular shocks

International Nuclear Information System (INIS)

Winske, D.; Giacalone, J.; Thomsen, M.F.; Mellott, M.M.

1987-01-01

Plasma heating due to the ion instability and the modified two-stream instability is examined for quasi-perpendicular subcritical shocks. Electron and ion heating is investigated as a function of upstream electron to ion temperature ratio and plasma beta using second-order heating rates. A simple shock model is employed in which the cross-field electron-ion drift speed is adjusted until the total (adiabatic plus anomalous) heating matches that required by the Rankine-Hugoniot relations. Quantities such as the width of the shock and the maximum electric field fluctuations are also calculated, and the results are compared with the ISEE data set of subcritical box shock crossings. The observed width of the shock, the amount of plasma heating, and the low-frequency electric field intensity are in reasonably good agreement with the calculations for the modified two-stream instability. On the other hand, the wave intensities at higher frequency are about 4 orders of magnitude smaller than those predicted for the ion acoustic instability at saturation, consistent with the fact that the measured shock widths imply cross-field drift speeds that are below threshold for this instability. It is therefore concluded that the dissipation at these shocks is most likely due to the lower frequency, modified two-stream instability

Lower hybrid waves at the shock front: a reassessment

Directory of Open Access Journals (Sweden)

S. N. Walker

2008-03-01

Full Text Available The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (ω=V_ik_⊥ and magnetised electrons (ω=V_ek_||. In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.

Electricity consumption, industrial production, and entrepreneurship in Singapore

International Nuclear Information System (INIS)

Sun, Sizhong; Anwar, Sajid

2015-01-01

Within the context of a tri-variate vector autoregressive framework that includes entrepreneurship, this paper examines the link between electricity consumption and industrial production in Singapore's manufacturing sector. Unlike the existing studies, this paper focuses on one sector of the economy and utilises a unique monthly dataset. Empirical analysis based on Johansen's cointegration approach shows that the three variables are cointegrated – i.e., a stable long-run relationship exists among electricity consumption, output and entrepreneurship in Singapore's manufacturing sector. Empirical analysis based on data from January 1983 to February 2014 reveals that electricity consumption adjusts very slowly to shocks to industrial production and entrepreneurship. Furthermore, entrepreneurship Granger causes electricity consumption, which causes industrial production. As electricity consumption causes industrial output, the growth hypothesis concerning energy consumption and economic growth holds in Singapore's manufacturing sector and policies that restrict electricity production, without electricity imports, are likely to lead to a decline in the manufacturing output. - Highlights: • Using a unique monthly dataset, we focus on Singapore's manufacturing sector. • Electricity consumption, output and entrepreneurship are cointegrated. • Electricity consumption adjusts very slowly to shocks to the other variables. • Entrepreneurship causes electricity consumption which causes industrial production. • We find that growth hypothesis governs the electricity consumption and real output

Influence of shock waves from plasma actuators on transonic and supersonic airflow

Science.gov (United States)

Mursenkova, I. V.; Znamenskaya, I. A.; Lutsky, A. E.

2018-03-01

This paper presents experimental and numerical investigations of high-current sliding surface discharges of nanosecond duration and their effect on high-speed flow as plasma actuators in a shock tube. This study deals with the effectiveness of a sliding surface discharge at low and medium air pressure. Results cover the electrical characteristics of the discharge and optical visualization of the discharge and high-speed post-discharge flow. A sliding surface discharge is first studied in quiescent air conditions and then in high-speed flow, being initiated in the boundary layer at a transverse flow velocity of 50-950 m s-1 behind a flat shock wave in air of density 0.04-0.45 kg m-3. The discharge is powered by a pulse voltage of 25-30 kV and the electric current is ~0.5 kA. Shadow imaging and particle image velocimetry (PIV) are used to measure the flow field parameters after the pulse surface discharge. Shadow imaging reveals shock waves originating from the channels of the discharge configurations. PIV is used to measure the velocity field resulting from the discharge in quiescent air and to determine the homogeneity of energy release along the sliding discharge channel. Semicylindrical shock waves from the channels of the sliding discharge have an initial velocity of more than 600 m s-1. The shock-wave configuration floats in the flow along the streamlined surface. Numerical simulation based on the equations of hydrodynamics matched with the experiment showed that 25%-50% of the discharge energy is instantly transformed into heat energy in a high-speed airflow, leading to the formation of shock waves. This energy is comparable to the flow enthalpy and can result in significant modification of the boundary layer and the entire flow.

9 CFR 313.30 - Electrical; stunning or slaughtering with electric current.

Science.gov (United States)

2010-01-01

... electrical shock shall be such as to produce immediate insensibility to pain in the exposed animal. (4) The... designed to properly accommodate the species of animals being anesthetized. Animals shall be free from pain... material. Power activated gates designed for constant flow of animals shall be so fabricated that they will...

Improvements in the electromechanical conversion of energy using shock waves

International Nuclear Information System (INIS)

Landure, Yves

1971-01-01

This report concerns the electrical mechanical conversion. In this study it was obtained by the depolarization of a ferroelectric ceramic. We are particularly interested by the high electrical horse-power. Shock wave which produces depolarization is created by a gun powder. The speed of the projectile is measured and the pressures generated in the ceramic is determined graphically. The energy freed is released on a linear resistive load. We were able to prove by different parameters how to obtain the maximum electrical energy. On a resistive load of 26 ohms, it was freed 0,91 J/cm 3 in less than 0,5 μs corresponding to an electrical horse-power superior to 2 MW/cm 3 . (author) [fr

Shock Dynamics in Stellar Outbursts. I. Shock Formation

Energy Technology Data Exchange (ETDEWEB)

Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

2017-05-20

Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

The evaluation and management of electrical storm.

Science.gov (United States)

Eifling, Michael; Razavi, Mehdi; Massumi, Ali

2011-01-01

Electrical storm is an increasingly common and life-threatening syndrome that is defined by 3 or more sustained episodes of ventricular tachycardia, ventricular fibrillation, or appropriate shocks from an implantable cardioverter-defibrillator within 24 hours. The clinical presentation can be dramatic. Electrical storm can manifest itself during acute myocardial infarction and in patients who have structural heart disease, an implantable cardioverter-defibrillator, or an inherited arrhythmic syndrome. The presence or absence of structural heart disease and the electrocardiographic morphology of the presenting arrhythmia can provide important diagnostic clues into the mechanism of electrical storm. Electrical storm typically has a poor outcome.The effective management of electrical storm requires an understanding of arrhythmia mechanisms, therapeutic options, device programming, and indications for radiofrequency catheter ablation. Initial management involves determining and correcting the underlying ischemia, electrolyte imbalances, or other causative factors. Amiodarone and β-blockers, especially propranolol, effectively resolve arrhythmias in most patients. Nonpharmacologic treatment, including radiofrequency ablation, can control electrical storm in drug-refractory patients. Patients who have implantable cardioverter-defibrillators can present with multiple shocks and may require drug therapy and device reprogramming. After the acute phase of electrical storm, the treatment focus should shift toward maximizing heart-failure therapy, performing revascularization, and preventing subsequent ventricular arrhythmias. Herein, we present an organized approach for effectively evaluating and managing electrical storm.

Introduction to Plasma Dynamo, Reconnection and Shocks

Energy Technology Data Exchange (ETDEWEB)

Intrator, Thomas P. [Los Alamos National Laboratory

2012-08-30

In our plasma universe, most of what we can observe is composed of ionized gas, or plasma. This plasma is a conducting fluid, which advects magnetic fields when it flows. Magnetic structure occurs from the smallest planetary to the largest cosmic scales. We introduce at a basic level some interesting features of non linear magnetohydrodynamics (MHD). For example, in our plasma universe, dynamo creates magnetic fields from gravitationally driven flow energy in an electrically conducting medium, and conversely magnetic reconnection annihilates magnetic field and accelerates particles. Shocks occur when flows move faster than the local velocity (sonic or Alfven speed) for the propagation of information. Both reconnection and shocks can accelerate particles, perhaps to gigantic energies, for example as observed with 10{sup 20} eV cosmic rays.

A structural VAR analysis of electricity consumption and real GDP: Evidence from the G7 countries

International Nuclear Information System (INIS)

Narayan, Paresh Kumar; Narayan, Seema; Prasad, Arti

2008-01-01

In this paper, we depart from the literature on electricity consumption-real GDP in that for the first time we examine the reaction of real GDP to shocks in electricity consumption. To achieve this goal, we use the structural vector autoregressive (SVAR) model and examine the impact of electricity consumption shocks on real GDP for the G7 countries. We find that except for the USA, electricity consumption has a statistically significant positive impact on real GDP over short horizons. This finding implies that except for the USA, electricity conservation policies will hurt real GDP in the G7 countries

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

Directory of Open Access Journals (Sweden)

V. V. Lobzin

2008-09-01

Full Text Available A new method for remote sensing of the quasiperpendicular part of the bow shock surface is presented. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock. Langmuir waves usually have maximum intensity at the upstream boundary of this region. All these waves are generated by energetic electrons accelerated by quasiperpendicular zone of the shock front. Nonstationary behavior of the shock, in particular due to rippling, should result in modulation of energetic electron fluxes, thereby giving rise to variations of Langmuir waves intensity. For upshifted and downshifted oscillations, the variations of both intensity and central frequency can be observed. For the present study, WHISPER measurements of electric field spectra obtained aboard Cluster spacecraft are used to choose 48 crossings of the electron foreshock boundary with dominating Langmuir waves and to perform for the first time a statistical analysis of nonstationary behavior of quasiperpendicular zone of the Earth's bow shock. Analysis of hidden periodicities in plasma wave energy reveals shock front nonstationarity in the frequency range 0.33 f_BiBi, where f_Bi is the proton gyrofrequency upstream of the shock, and shows that the probability to observe such a nonstationarity increases with Mach number. The profiles observed aboard different spacecraft and the dominating frequencies of the periodicities are usually different. Hence nonstationarity and/or rippling seem to be rather irregular both in space and time rather than resembling a quasiregular wave propagating on the shock surface.

Shock Waves Science and Technology Library

CERN Document Server

2012-01-01

This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with the fundamental theory of detonation physics in gaseous and condensed phase reactive media. The detonation process involves complex chemical reaction and fluid dynamics, accompanied by intricate effects of heat, light, electricity and magnetism - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The seven extensive chapters contained in this volume are: - Chemical Equilibrium Detonation (S. Bastea and LE Fried) - Steady One-Dimensional Detonations (A Higgins) - Detonation Instability (HD Ng and F Zhang) - Dynamic Parameters of Detonation (AA Vasiliev) - Multi-Scaled Cellular Detonation (D Desbordes and HN Presles) - Condensed Matter Detonation: Theory and Practice (C Tarver) - Theory of Detonation Shock Dynamics (JB Bdzil and DS Stewart) The chapters are thematically interrelated in a systematic descriptive appro...

Electricity and magnetism

CERN Document Server

Robertson, William C

2005-01-01

Shocked by static? Mixed up about magnets? Curious about currents? This book will help you get beyond memorizing electricity-related formulas, rules, and procedures so you can understand the topic at a deep level deep enough to teach it with confidence and comfort. By covering the basics of static electricity, current electricity, and magnetism, the book develops a scientific model showing that electricity and magnetism are really the same phenomenon in different forms. A bonus feature: access to interactive software that you can download from the NSTA Web site. The software will help you investigate electrical circuits from simple to complex without having to buy a lot of expensive materials (or risking electrocution!). Electricity and Magnetism is the fifth title in the award-winning NSTA Press Stop Faking It! Series. As author Bill Robertson writes, The book you have in your hands is not a textbook. It is, however, designed to help you get science at a level you never thought possible, and also to bring yo...

Shock-wave structure formation in a dusty plasma

International Nuclear Information System (INIS)

Popel', S.I.; Golub', A.P.; Loseva, T.V.; Bingkhem, R.; Benkadda, S.

2001-01-01

Nonstationary problem on evolution perturbation and its transformation into nonlinear wave structure is considered. The method developed permits finding solution to the system of nonlinear evolution equations describing dust particles with variable charge, Boltzmann electron and inertia ions. An accurate stationary solution as ion-sonic wave structures explained by anomalous dissipation due to electric discharge of dust particles was found. Evolution of two types of initial perturbations was studied, i.e.: soliton and immobile region with increased density of ions - a step. Soliton evolution in plasma with variable charge of dust particles results in the appearance on nonstationary shock-wave structure, whereas the step evolution gives rise to appearance of a shock wave similar to the stationary one along with rarefaction wave [ru

Slow shocks and their transition to fast shocks in the inner solar wind

International Nuclear Information System (INIS)

Wang, Y.C.

1987-01-01

The jump conditions of MHD shocks may be directly calculated as functions of three upstream conditions: the shock Alfven number based on the normal component of the relative shock speed, the shock angle, and the plasma β value. The shock Alfven number is less than 1 for a slow shock and greater than 1 for a fast shock. A traveling, forward shock can be a slow shock in coronal space, where the Alfven speed is of the order of 1000 km/s. The surface of a forward slow shock has a bow-shaped geometry with its nose facing toward the sun. The decrease in the Alfven speed at increasing heliocentric distance causes the shock Alfven number of a forward slow shock to become greater than 1, and the shock eventually evolves from a slow shock into a fast shock. During the transition the shock system consists of a slow shock, a fast shock, and a rotational discontinuity. They intersect along a closed transition line. As the system moves outward from the sun, the area enclosed by the transition line expands, the fast shock grows stronger, and the slow shock becomes weaker. Eventually, the slow shock diminishes, and the entire shock system evolves into a forward fast shock. copyrightAmerican Geophysical Union 1987

INFLUENCE OF ADDITIONAL VIBRATION IMPACT ON THE EFFECTIVENESS OF ELECTRICAL STIMULATION PROCEDURE

Directory of Open Access Journals (Sweden)

M. G. Kiselev

2017-01-01

Full Text Available An experimental instrument complex which includes hardware for performing complex procedures using electrical shock massager frictional action was performed. The aim of the study was to influence the additional vibration effect on the efficiency of the procedure of electrostimulation.In order to increase the efficiency of the procedure electrostimulation authors proposed to carry it out with using of massager shock-friction action. The changes of muscular indicator on different stimulation treatments was shown after a series of seven treatments .Results of the processing of the experimental data and its subsequent analysis found that the use of the vibration exposure is accompanied by increase of load parameters in untrained volunteers. The increase in contact area due to decrease in the distance between the nozzle and the axis of rotation of the tumbler body surface, increases the electrical efficiency of the procedure.On the basis of a generalized analysis of data reflecting the effect of inappropriate electrical stimulation, it was established that, in order to achieve the best results, oscillatory systems providing shock-friction mode of its interaction with the skin surface, in particular a shock-frictional massager, were used.

Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

International Nuclear Information System (INIS)

Hamilton, D.C.

1986-01-01

Measurements are reported for the electrical conductivity of liquid nitrogen (N 2 ), oxygen (O 2 ) and benzene (C 6 H 6 ), and Hugoniot equation of state of liquid 1-butene (C 4 H 8 ) under shock compressed conditions. The conductivity data span 7 x 10 -4 to 7 x 10 1 Ω -1 cm -1 over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs

Pavlovian conditioning of shock-induced suppression of lymphocyte reactivity: acquisition, extinction, and preexposure effects.

Science.gov (United States)

Lysle, D T; Cunnick, J E; Fowler, H; Rabin, B S

1988-01-01

Recent research has indicated that physical stressors, such as electric shock, can suppress immune function in rats. The present study investigated whether a nonaversive stimulus that had been associated with electric shock would also impair immune function. Presentation of that conditioned stimulus (CS) by itself produced a pronounced suppression of lymphocyte proliferation in response to the nonspecific mitogens, Concanavalin-A (ConA) and Phytohemagglutinin (PHA). In further evidence of a conditioning effect, the suppression was attenuated by extinction and preexposure manipulations that degraded the associative value of the CS. These results indicate that a psychological or learned stressor can suppress immune reactivity independently of the direct effect of physically aversive stimulation or of ancillary changes in dietary and health-related habits.

Pressurized thermal shock program sponsored by EPRI

International Nuclear Information System (INIS)

Stahlkopf, K.E.

1983-01-01

The potential for long term neutron embrittlement of reactor vessels has been recognized for a number of years. Reactor vessel thermal shock is not a new concern, but with a growing number of plants approaching their mid-lives, it is a concern that must be understood and dealt with. Recent attention has focused on the performance of vessels during overcooling transients. This concern was designated as Unresolved Safety Issue A-49 by the Nuclear Regulatory Commission in December 1981. The USNRC staff has identified eight overcooling events of concern in U.S. PWRs. The concern is currently limited to Pressurized Water Reactors. The Electric Power Research Institute (EPRI) has supported research on reactor vessel integrity for a number of years and has supported an extensive effort on reactor vessel pressurized thermal shock (PTS) over the last three years. In addition, EPRI has developed a linked set of computer codes to simulate the pressurized thermal shock transients and assess the integrity of the nuclear reactor vessels for various overcooling transients. This paper focuses on the integrated analysis approach being used by EPRI in performing such analysis. (orig.)

Shock Absorbers Save Structures and Lives during Earthquakes

Science.gov (United States)

2015-01-01

With NASA funding, North Tonawanda, New York-based Taylor Devices Inc. developed fluidic shock absorbers to safely remove the fuel and electrical connectors from the space shuttles during launch. The company is now employing the technology as seismic dampers to protect structures from earthquakes. To date, 550 buildings and bridges have the dampers, and not a single one has suffered damage in the wake of an earthquake.

Toxic shock syndrome

Science.gov (United States)

Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

Coronal mass ejection shock fronts containing the two types of intermediate shocks

International Nuclear Information System (INIS)

Steinolfson, R.S.; Hundhausen, A.J.

1990-01-01

Numerical solutions of the time-dependent, magnetohydrodynamic (MHD) equations in two dimensions are used to demonstrate the formation of both types of intermediate shocks in a single shock front for physical conditions that are an idealization of those expected to occur in some observed coronal mass ejections. The key to producing such a shock configuration in the simulations is the use of an initial atmosphere containing a magnetic field representative of that in a coronal streamer with open field lines overlying a region of closed field lines. Previous attempts using just open field lines (perpendicular to the surface) produced shock configurations containing just one of the two intermediate shock types. A schematic of such a shock front containing both intermediate shock types has been constructed previously based solely on the known properties of MHD shocks from the Rankine-Hugoniot equations and specific requirements placed on the shock solution at points along the front where the shock normal and upstream magnetic field are aligned. The shock front also contains, at various locations along the front, a hydrodynamic (nonmagnetic) shock, a switch-on shock, and a fast shock in addition to the intermediate shocks. This particular configuration occurs when the shock front speed exceeds the upstream (preshock) intermediate wave speed but is less than a critical speed defined in the paper (equation 1) along at least some portion of the shock front. A distinctive feature of the front is that it is concave upward (away from the surface) near the region where the field in the preshock plasma is normal to the front of near the central portion of the shock front

demystifying the shock of shocking

African Journals Online (AJOL)

(with a pulse), atrial fibrillation and atrial flutter. The energy dose in cardioversion is less (0.5. - 2 J/kg) than in defibrillation (2 - 4 J/kg). In cardioversion the shock is discharged synchronously with the native R wave of the patient. Without synchronisation,. VF can be induced if a shock is delivered during the refractory period ...

Shock absorbing structure

International Nuclear Information System (INIS)

Kojima, Naoki; Matsushita, Kazuo.

1992-01-01

Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

Electrical conductivity of air under the action of a shock wave; Conductivite electrique de l'air sous l'action d'une onde de choc

Energy Technology Data Exchange (ETDEWEB)

Thouvenin, Jacques [Commissariat a l' energie atomique et aux energies alternatives - CEA (France)

1960-07-01

A method is described for the measurement of the electrical conductivity of a shock wave in air. The results reveal the preponderant part played by the NO molecule. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 302-304, sitting of 11 January 1960 [French] On decrit un procede de mesure de la conductivite electrique d'une onde de choc dans l'air. Les resultats font apparaitre le role preponderant joue par la molecule NO. Reproduction d'un article publie dans les Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 302-304, seance du 11 janvier 1960.

Frequent Home Monitoring of ICD Is Effective to Prevent Inappropriate Defibrillator Shock Delivery

Directory of Open Access Journals (Sweden)

Paolo Bifulco

2014-01-01

Full Text Available Recently, in the context of telemedicine, telemonitoring services are gaining attention. They are offered, for example, to patients with implantable cardioverter defibrillators (ICDs. A major problem associated with ICD therapy is the occurrence of inappropriate shocks which impair patients’ quality of life and may also be arrhythmogenic. The telemonitoring can provide a valid support to intensify followup visits, in order to improve the prevention of inappropriate defibrillator shock, thus enhancing patient safety. Inappropriate shock generally depends on atrial fibrillation, supraventricular tachycardia, and abnormal sensing (such as those caused by electromagnetic interferences. As a practical example, an unusual case of an ICD patient who risked an inappropriate shock while taking a shower is reported. Continuous remote telemonitoring was able to timely warn cardiologist via GSM-SMS, who were able to detect improper sensing examining the intracardiac electrogram via Web. Patient was promptly contacted and warned to not further come in contact with the hydraulic system and any electrical appliance to prevent an inappropriate defibrillator shock. This demonstrates the effectiveness and usefulness of continuous remote telemonitoring in supporting ICD patients.

Electricity spot price dynamics: Beyond financial models

International Nuclear Information System (INIS)

Guthrie, Graeme; Videbeck, Steen

2007-01-01

We reveal properties of electricity spot prices that cannot be captured by the statistical models, commonly used to model financial asset prices, that are increasingly used to model electricity prices. Using more than eight years of half-hourly spot price data from the New Zealand Electricity Market, we find that the half-hourly trading periods fall naturally into five groups corresponding to the overnight off-peak, the morning peak, daytime off-peak, evening peak, and evening off-peak. The prices in different trading periods within each group are highly correlated with each other, yet the correlations between prices in different groups are lower. Models, adopted from the modeling of security prices, that are currently applied to electricity spot prices are incapable of capturing this behavior. We use a periodic autoregression to model prices instead, showing that shocks in the peak periods are larger and less persistent than those in off-peak periods, and that they often reappear in the following peak period. In contrast, shocks in the off-peak periods are smaller, more persistent, and die out (perhaps temporarily) during the peak periods. Current approaches to modeling spot prices cannot capture this behavior either. (author)

[Electrical storm].

Science.gov (United States)

Barnay, C; Taieb, J; Morice, R

2007-11-01

Electrical storm is defined as repeated occurrence of severe ventricular arrhythmias requiring multiple cardioversions, two or more or three or more following different studies. The clinical aspect can sometimes be made of multiple, self aggravating, life threatening accesses. There are three main clinical circumstances of occurrence: in patients equipped with intracardiac defibrillators, during the acute phase of myocardial infarction and in Brugada syndrome. 10 to 15% of patients with cardiac defibrillators are subject to electrical storms in a period of two years. The causative arrhythmia is most often ventricular tachycardia than ventricular fibrillation, especially in secondary prevention and if the initial arrhythmias justifying the device was a ventricular tachycardia. Precipitaing factors are present in one third of cases, mainly acute heart failure, ionic disorders and arrhythmogenic drugs. Predictive factors are age, left ventricular ejection fractionelectrical shock in 50% of cases, antitachycardi stimulation in 30% and in 20% by association of the two. Treatment, after elimination of inappropriate shocks, is mainly based on beta-blockers and amiodarone, class I antiarrhythmics, lidocaïne or bretylium in some cases, and sedation pushed to general anesthesia in some cases. Radio-frequency ablation and even heart transplantation have been proposed in extreme cases. Quinidine has been proved efficient in cases of Brugada syndrome.

Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)

2017-07-15

The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.

Non-stationarity of the quasi-perpendicular bow shock: comparison between Cluster observations and simulations

Directory of Open Access Journals (Sweden)

H. Comişel

2011-02-01

Full Text Available We have performed full particle electromagnetic simulations of a quasi-perpendicular shock. The shock parameters have been chosen to be appropriate for the quasi-perpendicular Earth's bow shock observed by Cluster on 24 January 2001 (Lobzin et al., 2007. We have performed two simulations with different ion to electron mass ratio: run 1 with mi/me=1840 and run 2 with mi/me=100. In run 1 the growth rate of the modified two-stream instability (MTSI is large enough to get excited during the reflection and upstream gyration of part of the incident solar wind ions. The waves due to the MTSI are on the whistler mode branch and have downstream directed phase velocities in the shock frame. The Poynting flux (and wave group velocity far upstream in the foot is also directed in the downstream direction. However, in the density and magnetic field compression region of the overshoot the waves are refracted and the Poynting flux in the shock frame is directed upstream. The MTSI is suppressed in the low mass ratio run 2. The low mass ratio run shows more clearly the non-stationarity of the shock with a larger time scale of the order of an inverse ion gyrofrequency (Ωci: the magnetic field profile flattens and steepens with a period of ~1.5Ωci−1. This non-stationarity is different from reformation seen in previous simulations of perpendicular or quasi-perpendicular shocks. Beginning with a sharp shock ramp the large electric field in the normal direction leads to high reflection rate of solar wind protons. As they propagate upstream, the ion bulk velocity decreases and the magnetic field increases in the foot, which results in a flattening of the magnetic field profile and in a decrease of the normal electric field. Subsequently the reflection rate decreases and the whole shock profile steepens again. Superimposed on this 'breathing' behavior are in the realistic mass ratio case the waves due to the MTSI. The simulations lead us to a re-interpretation of

Collisionless electrostatic shocks

DEFF Research Database (Denmark)

Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

1970-01-01

An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

Electrical response of relaxing dielectrics compressed by arbitrary stress pulses

International Nuclear Information System (INIS)

Lysne, P.C.

1983-01-01

The theoretical problem of the electric response of biased dielectrics and piezoelectrics subjected to planar stress pulse loading is considered. The materials are taken to exhibit dielectric relaxation in the sense that changes in the polarization induced by electric fields do not occur instantaneously with changes in the fields. While this paper considers arbitrary stress pulse loading of the specimen, examples that are amenable to projectile impact techniques are considered in detail. They are shock reverberation, thin pulse, and ramp loading experiments. It is anticipated that these experiments will play a role in investigations of dielectric relaxation caused by shock induced damage in insulators

Convergence of shock waves between conical and parabolic boundaries

Energy Technology Data Exchange (ETDEWEB)

Yanuka, D.; Zinowits, H. E.; Antonov, O.; Efimov, S.; Virozub, A.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2016-07-15

Convergence of shock waves, generated by underwater electrical explosions of cylindrical wire arrays, between either parabolic or conical bounding walls is investigated. A high-current pulse with a peak of ∼550 kA and rise time of ∼300 ns was applied for the wire array explosion. Strong self-emission from an optical fiber placed at the origin of the implosion was used for estimating the time of flight of the shock wave. 2D hydrodynamic simulations coupled with the equations of state of water and copper showed that the pressure obtained in the vicinity of the implosion is ∼7 times higher in the case of parabolic walls. However, comparison with a spherical wire array explosion showed that the pressure in the implosion vicinity in that case is higher than the pressure in the current experiment with parabolic bounding walls because of strong shock wave reflections from the walls. It is shown that this drawback of the bounding walls can be significantly minimized by optimization of the wire array geometry.

Lunar Surface Potential Increases during Terrestrial Bow Shock Traversals

Science.gov (United States)

Collier, Michael R.; Stubbs, Timothy J.; Hills, H. Kent; Halekas, Jasper; Farrell, William M.; Delory, Greg T.; Espley, Jared; Freeman, John W.; Vondrak, Richard R.; Kasper, Justin

2009-01-01

Since the Apollo era the electric potential of the Moon has been a subject of interest and debate. Deployed by three Apollo missions, Apollo 12, Apollo 14 and Apollo 15, the Suprathermal Ion Detector Experiment (SIDE) determined the sunlit lunar surface potential to be about +10 Volts using the energy spectra of lunar ionospheric thermal ions accelerated toward the Moon. We present an analysis of Apollo 14 SIDE "resonance" events that indicate the lunar surface potential increases when the Moon traverses the dawn bow shock. By analyzing Wind spacecraft crossings of the terrestrial bow shock at approximately this location and employing current balancing models of the lunar surface, we suggest causes for the increasing potential. Determining the origin of this phenomenon will improve our ability to predict the lunar surface potential in support of human exploration as well as provide models for the behavior of other airless bodies when they traverse similar features such as interplanetary shocks, both of which are goals of the NASA Lunar Science Institute's Dynamic Response of the Environment At the Moon (DREAM) team.

Comparisons of Air Radiation Model with Shock Tube Measurements

Science.gov (United States)

Bose, Deepak; McCorkle, Evan; Bogdanoff, David W.; Allen, Gary A., Jr.

2009-01-01

This paper presents an assessment of the predictive capability of shock layer radiation model appropriate for NASA s Orion Crew Exploration Vehicle lunar return entry. A detailed set of spectrally resolved radiation intensity comparisons are made with recently conducted tests in the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. The spectral range spanned from vacuum ultraviolet wavelength of 115 nm to infrared wavelength of 1400 nm. The analysis is done for 9.5-10.5 km/s shock passing through room temperature synthetic air at 0.2, 0.3 and 0.7 Torr. The comparisons between model and measurements show discrepancies in the level of background continuum radiation and intensities of atomic lines. Impurities in the EAST facility in the form of carbon bearing species are also modeled to estimate the level of contaminants and their impact on the comparisons. The discrepancies, although large is some cases, exhibit order and consistency. A set of tests and analyses improvements are proposed as forward work plan in order to confirm or reject various proposed reasons for the observed discrepancies.

Impact Responses and Parameters Sensitivity Analysis of Electric Wheelchairs

Directory of Open Access Journals (Sweden)

Song Wang

2018-06-01

Full Text Available The shock and vibration of electric wheelchairs undergoing road irregularities is inevitable. The road excitation causes the uneven magnetic gap of the motor, and the harmful vibration decreases the recovery rate of rehabilitation patients. To effectively suppress the shock and vibration, this paper introduces the DA (dynamic absorber to the electric wheelchair. Firstly, a vibration model of the human-wheelchair system with the DA was created. The models of the road excitation for wheelchairs going up a step and going down a step were proposed, respectively. To reasonably evaluate the impact level of the human-wheelchair system undergoing the step–road transition, evaluation indexes were given. Moreover, the created vibration model and the road–step model were validated via tests. Then, to reveal the vibration suppression performance of the DA, the impact responses and the amplitude frequency characteristics were numerically simulated and compared. Finally, a sensitivity analysis of the impact responses to the tire static radius r and the characteristic parameters was carried out. The results show that the DA can effectively suppress the shock and vibration of the human-wheelchair system. Moreover, for the electric wheelchair going up a step and going down a step, there are some differences in the vibration behaviors.

Mild electrical stimulation with heat stimulation increase heat shock protein 70 in articular chondrocyte.

Science.gov (United States)

Hiraoka, Nobuyuki; Arai, Yuji; Takahashi, Kenji A; Mazda, Osam; Kishida, Tsunao; Honjo, Kuniaki; Tsuchida, Shinji; Inoue, Hiroaki; Morino, Saori; Suico, Mary Ann; Kai, Hirofumi; Kubo, Toshikazu

2013-06-01

The objective of this study is to investigate the effects of mild electrical stimulation (MES) and heat stress (HS) on heat shock protein 70 (HSP70), that protects chondrocytes and enhances cartilage matrix metabolism, in chondrocyte and articular cartilage. Rabbit articular chondrocytes were treated with MES and/or HS. The safeness was assessed by LDH assay and morphology. HSP70 protein, ubiquitinated proteins and HSP70 mRNA were examined by Western blotting and real-time PCR. Rat knee joints were treated with MES and/or HS. HSP70 protein, ubiquitinated proteins, HSP70 mRNA and proteoglycan core protein (PG) mRNA in articular cartilage were investigated. In vitro, HS increased HSP70 mRNA and HSP70 protein. MES augmented ubiquitinated protein and HSP70 protein, but not HSP70 mRNA. MES + HS raised HSP70 mRNA and ubiquitinated protein, and significantly increased HSP70 protein. In vivo, HS and MES + HS treatment augmented HSP70 mRNA. HS modestly augmented HSP70 protein. MES + HS significantly increased HSP70 protein and ubiquitinated proteins. PG mRNA was markedly raised by MES + HS. This study demonstrated that MES, in combination with HS, increases HSP70 protein in chondrocytes and articular cartilage, and promotes cartilage matrix metabolism in articular cartilage. MES in combination with HS can be a novel physical therapy for osteoarthritis by inducing HSP70 in articular cartilage. Copyright © 2013 Orthopaedic Research Society.

Massive Electrical Storm at Disease Onset in a Patient with Brugada Syndrome

DEFF Research Database (Denmark)

Pallisgaard, Jannik L; Gang, Uffe; Kanters, Jørgen K.

2014-01-01

Background Brugada syndrome (BrS) is a genetic arrhythmogenic disease characterized by ST-segment elevations in the right precordial leads of the electrocardiogram (ECG). These ECG changes may be concealed and BrS may present with electrical storm characterized by recurrent ventricular tachycardia...... and fibrillation. Case Report A 49-year-old previously healthy man was admitted with electrical storm. The patient received direct current (DC) cardioversion shocks and only after intravenous lidocaine did the electrical storm slowly subside with a total of 255 DC shocks administered during the first 24 h after...... admission. He fully recovered and received an implantable cardioverter-defibrillator. Subsequent drug challenge with flecainide revealed type 1 BrS. Conclusions Massive electrical storm can be the first symptom of BrS and the diagnostic ECG changes may be concealed at presentation. Although hundreds of DC...

Strong ion accelerating by collisionless magnetosonic shock wave propagating perpendicular to a magnetic field

International Nuclear Information System (INIS)

Ohsawa, Yukiharu.

1984-12-01

A 2-1/2 dimensional fully relativistic, fully electromagnetic particle code is used to study a time evolution of nonlinear magnetosonic pulse propagating in the direction perpendicular to a magnetic field. The pulse is excited by an instantaneous piston acceleration, and evolves totally self-consistently. Large amplitude pulse traps some ions and accelerates them parallel to the wave front. They are detrapped when their velocities become of the order of the sum of the ExB drift velocity and the wave phase velocity, where E is the electric field in the direction of wave propagation. The pulse develops into a quasi-shock wave in a collisionless plasma by a dissipation due to the resonant ion acceleration. Simple nonlinear wave theory for a cold plasma well describes the shock properties observed in the simulation except for the effects of resonant ions. In particular, magnitude of an electric potential across the shock region is derived analytically and is found to be in good agreement with our simulations. The potential jump is proportional to B 2 , and hence the ExB drift velocity of the trapped ions is proportional to B. (author)

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

Science.gov (United States)

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.

Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

Energy Technology Data Exchange (ETDEWEB)

Hamilton, D.C.

1986-10-08

Measurements are reported for the electrical conductivity of liquid nitrogen (N/sub 2/), oxygen (O/sub 2/) and benzene (C/sub 6/H/sub 6/), and Hugoniot equation of state of liquid 1-butene (C/sub 4/H/sub 8/) under shock compressed conditions. The conductivity data span 7 x 10/sup -4/ to 7 x 10/sup 1/ ..cap omega../sup -1/cm/sup -1/ over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs.

Effects of Atwood number on shock focusing in shock-cylinder interaction

Science.gov (United States)

Ou, Junfeng; Ding, Juchun; Luo, Xisheng; Zhai, Zhigang

2018-02-01

The evolution of shock-accelerated heavy-gas cylinder surrounded by the air with different Atwood numbers (A_t=0.28, 0.50, 0.63) is investigated, concentrating on shock focusing and jet formation. Experimentally, a soap film technique is used to generate an ideal two-dimensional discontinuous gas cylinder with a clear surface, which can guarantee the observation of shock wave movements inside the cylinder. Different Atwood numbers are realized by different mixing ratios of SF_6 and air inside the cylinder. A high-speed schlieren system is adopted to capture the shock motions and jet morphology. Numerical simulations are also performed to provide more information. The results indicate that an inward jet is formed for low Atwood numbers, while an outward jet is generated for high Atwood numbers. Different Atwood numbers will lead to the differences in the relative velocities between the incident shock and the refraction shock, which ultimately results in the differences in shock competition near the downstream pole. The morphology and feature of the jet are closely associated with the position and intensity of shock focusing. The pressure and vorticity contours indicate that the jet formation should be attributed to the pressure pulsation caused by shock focusing, and the jet development is ascribed to the vorticity induction. Finally, a time ratio proposed in the previous work for determining the shock-focusing type is verified by experiments.

Experimental study on underwater electrical explosion of a copper wire

International Nuclear Information System (INIS)

Zhou Qing; Zhang Jun; Tan Xiangyu; Ren Baozhong; Zhang Qiaogen

2010-01-01

Through analyzing the physical process of underwater electrical wire explosion, electrical wire explosions with copper wires were investigated underwater using pulsed voltage in the time scale of a few microseconds. A self-integrating Rogowsky coil and a voltage divider were used for current and voltage at the wire load, respectively. The shock wave pressure is measured with a piezoelectric pressure probe at the same distance. The current rise rate was adjusted by changing the applied voltage, circuit inductance, length and diameter of copper wire. The change of the current rise rate had a great effect on the process of underwater electrical wire explosion with copper wires. At last, the effect of discharge voltage, circuit inductance, length and diameter of copper wire were obtained on the explosion voltage and current as well as shock wave pressure. (authors)

The cost of nuclear electricity: economic values and political calculations

International Nuclear Information System (INIS)

Stauffer, T.

1985-01-01

The subject is covered in sections: introduction (monetary inflation; US-style rate-base formula; cost escalation); electricity generation costs (rate-base calculation formula; regulatory versus economic costs; inflationary case; cost-of-service rates versus inflation; first year electricity costs); rate shock (A. comparison with oil; B. nuclear case; C. comparison with coal/nuclear system; vintaged electricity costs versus growth and inflation); conclusions. (U.K.)

Shock parameter calculations at weak interplanetary shock waves

Directory of Open Access Journals (Sweden)

J. M. Gloag

2005-02-01

Full Text Available A large set of interplanetary shock waves observed using the Ulysses spacecraft is analysed in order to determine their local parameters. For the first time a detailed analysis is extended to the thermodynamic properties of a large number of events. The intention is to relate the shock parameters to the requirements set by MHD shock theory. A uniform approach is adopted in the selection of up and downstream regions for this analysis and applied to all the shock waves. Initially, the general case of a 3 component adiabatic plasma is considered. However, the calculation of magnetosonic and Alfvénic Mach numbers and the ratio of downstream to upstream entropy produce some unexpected results. In some cases there is no clear increase in entropy across the shock and also the magnetosonic Mach number can be less than 1. It is found that a more discerning use of data along with an empirical value for the polytropic index can raise the distribution of downstream to upstream entropy ratios to a more acceptable level. However, it is also realised that many of these shocks are at the very weakest end of the spectrum and associated phenomena may also contribute to the explanation of these results.

Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

Energy Technology Data Exchange (ETDEWEB)

Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2013-04-15

We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

Yield strength measurement of shock-loaded metal by flyer-impact perturbation method

Science.gov (United States)

Ma, Xiaojuan; Shi, Zhan

2018-06-01

Yield strength is one of the most important physical properties of a solid material, especially far from its melting line. The flyer-impact perturbation method measures material yield strength on the basis of correlation between the yield strength under shock compression and the damping of oscillatory perturbations in the shape of a shock front passing through the material. We used flyer-impact experiments on targets with machined grooves on the impact surface of shock 6061-T6 aluminum to between 32 and 61 GPa and recorded the evolution of the shock front perturbation amplitude in the sample with electric pins. Simulations using the elastic-plastic model can be matched to the experiments, explaining well the form of the perturbation decay and constraining the yield strength of 6061-T6 aluminum to be 1.31-1.75 GPa. These results are in agreement with values obtained from reshock and release wave profiles. We conclude that the flyer-impact perturbation method is indeed a new means to measure material strength.

Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator

Directory of Open Access Journals (Sweden)

Xiaoqiu Xu

2017-01-01

Full Text Available The simulation of regular shock wave (e.g., half-sine can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.

Measurement and Prediction of Radiative Non-Equilibrium for Air Shocks Between 7-9 km/s

Science.gov (United States)

Cruden, Brett A.; Brandis, Aaron M.

2017-01-01

The present paper describes a recent characterization of thermochemical non-equilibrium for shock speeds between 7 and 9 km/s in the NASA Ames Electric Arc Shock Tube (EAST) Facility. Data are spectrally resolved from 190-1450 nm and spatially resolved behind the shock front. The data are analyzed in terms of a spectral non-equilibrium metric, defined as the average radiance within +/- 2 cm of the peak. Simulations with DPLR/NEQAIR using different rate chemistries show these conditions to be poorly replicated. The sources of discrepancy are examined, leading to an update to the NEQAIR non-Boltzmann model and DPLR rate chemistry. New parameters for the rate chemistry and non-Boltzmann modeling are reported.

Alfven shock trains

International Nuclear Information System (INIS)

Malkov, M.A.; Kennel, C.F.; Wu, C.C.; Pellat, R.; Shapiro, V.D.

1991-01-01

The Cohen--Kulsrud--Burgers equation (CKB) is used to consider the nonlinear evolution of resistive, quasiparallel Alfven waves subject to a long-wavelength, plane-polarized, monochromatic instability. The instability saturates by nonlinear steepening, which proceeds until the periodic waveform develops an interior scale length comparable to the dissipation length; a fast or an intermediate shock then forms. The result is a periodic train of Alfven shocks of one or the other type. For propagation strictly parallel to the magnetic field, there will be two shocks per instability wavelength. Numerical integration of the time-dependent CKB equation shows that an initial, small-amplitude growing wave asymptotes to a stable, periodic stationary wave whose analytic solution specifies how the type of shock embedded in the shock train, and the amplitude and speed of the shock train, depend on the strength and phase of the instability. Waveforms observed upstream of the Earth's bowshock and cometary shocks resemble those calculated here

Spherical strong-shock generation for shock-ignition inertial fusion

Energy Technology Data Exchange (ETDEWEB)

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. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Nora, R.; Betti, R. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Department of Mechanical Engineering and Department of Physics, University of Rochester, Rochester, New York 14623 (United States); Casner, A.; Reverdin, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Ribeyre, X.; Vallet, A. [Université de Bordeaux-CNRS-CEA, CELIA (Centre Lasers Intenses et Applications) UMR 5107 F-33400 Talence (France); Peebles, J.; Beg, F. N. [University of California, San Diego, La Jolla, California 92093 (United States); 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.

Is shock index associated with outcome in children with sepsis/septic shock?*.

Science.gov (United States)

Yasaka, Yuki; Khemani, Robinder G; Markovitz, Barry P

2013-10-01

To investigate the association between PICU shock index (the ratio of heart rate to systolic blood pressure) and PICU mortality in children with sepsis/septic shock. To explore cutoff values for shock index for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome, and how the use of vasoactive therapy may affect shock index and its association with outcome. Retrospective cohort. Single-center tertiary PICU. Five hundred forty-four children with the diagnosis of sepsis/septic shock. None. From January 2003 to December 2009, 544 children met International Pediatric Sepsis Consensus Conference of 2005 criteria for sepsis/septic shock. Overall mortality was 23.7%. Among all patients, hourly shock index was associated with mortality: odds ratio of ICU mortality at 0 hour, 1.08, 95% CI (1.04-1.12); odds ratio at 1 hour, 1.09 (1.04-1.13); odds ratio at 2 hours, 1.09 (1.05-1.13); and odds ratio at 6 hours, 1.11 (1.06-1.15). When stratified by age, early shock index was associated with mortality only in children 1-3 and more than or equal to 12 years old. Area under the receiver operating characteristic curve in age 1-3 and more than or equal to 12 years old for shock index at admission was 0.69 (95% CI, 0.58-0.80) and 0.62 (95% CI, 0.52-0.72) respectively, indicating a fair predictive marker. Although higher shock index was associated with increased risk of mortality, there was no particular cutoff value with adequate positive or negative likelihood ratios to identify mortality in any age group of children. The improvement of shock index in the first 6 hours of ICU admission was not associated with outcome when analyzed in all patients. However, among patients whose shock index were above the 50th percentile at ICU admission for each age group, improvement of shock index was associated with lower ICU mortality in children between 1-3 and more than or equal to 12 years old (p = 0.02 and p = 0.03, respectively). When

Attentional Bias for Uncertain Cues of Shock in Human Fear Conditioning: Evidence for Attentional Learning Theory

Science.gov (United States)

Koenig, Stephan; Uengoer, Metin; Lachnit, Harald

2017-01-01

We conducted a human fear conditioning experiment in which three different color cues were followed by an aversive electric shock on 0, 50, and 100% of the trials, and thus induced low (L), partial (P), and high (H) shock expectancy, respectively. The cues differed with respect to the strength of their shock association (L H). During conditioning we measured pupil dilation and ocular fixations to index differences in the attentional processing of the cues. After conditioning, the shock-associated colors were introduced as irrelevant distracters during visual search for a shape target while shocks were no longer administered and we analyzed the cues’ potential to capture and hold overt attention automatically. Our findings suggest that fear conditioning creates an automatic attention bias for the conditioned cues that depends on their correlation with the aversive outcome. This bias was exclusively linked to the strength of the cues’ shock association for the early attentional processing of cues in the visual periphery, but additionally was influenced by the uncertainty of the shock prediction after participants fixated on the cues. These findings are in accord with attentional learning theories that formalize how associative learning shapes automatic attention. PMID:28588466

Biomass shock pretreatment

Science.gov (United States)

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.

THE EFFECT OF LARGE-SCALE MAGNETIC TURBULENCE ON THE ACCELERATION OF ELECTRONS BY PERPENDICULAR COLLISIONLESS SHOCKS

International Nuclear Information System (INIS)

Guo Fan; Giacalone, Joe

2010-01-01

We study the physics of electron acceleration at collisionless shocks that move through a plasma containing large-scale magnetic fluctuations. We numerically integrate the trajectories of a large number of electrons, which are treated as test particles moving in the time-dependent electric and magnetic fields determined from two-dimensional hybrid simulations (kinetic ions and fluid electron). The large-scale magnetic fluctuations effect the electrons in a number of ways and lead to efficient and rapid energization at the shock front. Since the electrons mainly follow along magnetic lines of force, the large-scale braiding of field lines in space allows the fast-moving electrons to cross the shock front several times, leading to efficient acceleration. Ripples in the shock front occurring at various scales will also contribute to the acceleration by mirroring the electrons. Our calculation shows that this process favors electron acceleration at perpendicular shocks. The current study is also helpful in understanding the injection problem for electron acceleration by collisionless shocks. It is also shown that the spatial distribution of energetic electrons is similar to in situ observations. The process may be important to our understanding of energetic electrons in planetary bow shocks and interplanetary shocks, and explaining herringbone structures seen in some type II solar radio bursts.

Plasma waves in the Earth's foreshock, bow shock, and magnetosheath

International Nuclear Information System (INIS)

Onsager, T.G.

1988-01-01

The research presented in this dissertation is a detailed analysis of electrostatic waves in the Earth's foreshock, bow shock, and magnetosheath. The wave modes measured in these regions, the possible generation mechanisms, and the process which drive the plasma to its unstable state are investigated. The measurements used in this study were obtained from the plasma wave receiver, the particle instrument, and the magnetometer on board the Active Magnetospheric Particle Tracer Explorer (AMPTE) Ion Release Module (IRM). Electron beam mode waves have been identified in the Earth's foreshock. A technique is developed which allows the rest frame frequency and wave number of the electron beam mode waves to be determined from the measurements. The experimentally determined values are compared with theoretical predictions, and approximate limits are put on the beam temperatures. It is demonstrated that electrostatic waves are present in the bow shock and magnetosheath with frequencies above the maximum frequency for Doppler shifted ion acoustic waves, yet below the Langmuir frequency. Waves in this frequency range are tentatively identified as electron beam mode waves. This identification is based on the measured frequencies and electric field polarization directions. Data from 45 bow shock crossings are then used to investigate possible correlations between the electron beam mode waves and the near shock plasma parameters. The best correlations are found with Alfven Mach number and electron beta. Possible mechanism which might produce electron beams in the shock and magnetosheath are discussed in terms of the correlation study results

Outputs of shock-loaded small piezoceramic disks

International Nuclear Information System (INIS)

Charest, Jacques A.; Mace, Jonathan Lee

2002-01-01

Thin small-diameter polycrystalline Lead-Zirconate-Titanate piezoceramic disks were shock loaded in the D33 orientation over a stress range of 0.1-30 GPa. Their electrical outputs were discharged into 50 Ω viewing resistors, producing typically 0.15 μs quasi-triangular impulses ranging from 50-700 V. The gas gun flat plate impact approach and the high explosives (HE) plane wave lens approach were used to load piezoceramic elements. These piezoceramic elements consisted of 0.25 mm thick and 1.32 mm diameter disks that were ultrasonically machined from 25 mm piezocrystal disks of type APC 850, commercially produced by American Piezo Ceramic Inc. To facilitate our experiments, the piezoceramic elements were coaxially mounted at the tip of a 2.35 mm diameter brass tube, an arrangement that is commercialized by Dynasen, Inc. under the name Piezopin of model CA-1136. Simple calculations on the electrical outputs produced by these piezoceramic disks reveal electrical outputs in excess of 3000 W. Such short bursts of electrical energy have the potential for numerous applications where critical timing is needed to observe fast transient events

Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

Science.gov (United States)

Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

2013-05-01

In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity. Copyright © 2013 Wiley Periodicals, Inc.

Cosmic-ray shock acceleration in oblique MHD shocks

Science.gov (United States)

Webb, G. M.; Drury, L. OC.; Volk, H. J.

1986-01-01

A one-dimensional, steady-state hydrodynamical model of cosmic-ray acceleration at oblique MHD shocks is presented. Upstream of the shock the incoming thermal plasma is subject to the adverse pressure gradient of the accelerated particles, the J x B force, as well as the thermal gas pressure gradient. The efficiency of the acceleration of cosmic-rays at the shock as a function of the upstream magnetic field obliquity and upstream plasma beta is investigated. Astrophysical applications of the results are briefly discussed.

Reflection of the solar wind ions at the earth's bow shock: energization

International Nuclear Information System (INIS)

Bonifazi, C.; Moreno, G.; Russell, C.T.

1983-01-01

The energies of the field-aligned proton beams observed upstream of the earth's bow shock are tested, on a statistical basis, against a simple reflection model. The comparison is carried out using both plasma and magnetic field data collected by the ISEE 2 spacecraft. The observations refer to the period from November 5 to December 20, 1977. According to this model, some of the solar wind protons incident upon the earth's shock front when reflected upstream gain energy by displacement parallel to the interplanetary electric field. The energy gained in the reflection can be described as a function of the angles between the interplanetary magnetic field, the solar wind bulk velocity, and the local shock normal. The task of finding these angles, i.e., the expected source point of the reflected ions at the earth's shock front, has been resolved using both the measured magnetic field direction and actual beam trajectory. The latter method, which takes into account the ion drift velocity, leads to a better agreement between theory and observations when far from the shock. In particular, it allows us to check the energies of the field-aligned beams even when they are observed far from the earth's bow shock (at distances up to 10-15 R/sub E/). We confirm, on a statistical basis, the test of the model recently carried out using the Los Alamos National Laboratory/Max-Planck-extraterrestrische observations on ISEE 1 and 2. We infer that reflected beams can sometimes propagate far upstream of the earth's bow shock without changing their energy properties

Thermophysical properties of liquid carbon dioxide under shock compressions: quantum molecular dynamic simulations.

Science.gov (United States)

Wang, Cong; Zhang, Ping

2010-10-07

Quantum molecular dynamics were used to calculate the equation of state, electrical, and optical properties of liquid carbon dioxide along the Hugoniot at shock pressures up to 74 GPa. The principal Hugoniot derived from the calculated equation of state is in good agreement with experimental results. Molecular dissociation and recombination are investigated through pair correlation functions and decomposition of carbon dioxide is found to be between 40 and 50 GPa along the Hugoniot, where nonmetal-metal transition is observed. In addition, the optical properties of shock compressed carbon dioxide are also theoretically predicted along the Hugoniot.

Electric rate shock and the future of utility construction

International Nuclear Information System (INIS)

Nogee, A.J.

1985-01-01

How state regulators spread the costs of overbudget and, in some cases, unneeded new power plants looms as a major political and economic issue directly affecting more than a third of the nation's households and businesses. Today's local battles over rate shock have an even greater national significance because they will shape investment incentives for decades to come. In addition to mismanaged nuclear projects, most nuclear and coal plants being finished today represent excess generating capacity. Utility reserve margins averaged 34% last year instead of the 15-20% above peak demand that analysts agree is desirable. State regulators are increasingly refusing to allow utilities to include new plants in the rate base, and utilities are responding with warnings about future shortages. They may also try to reform or repeal the Holding Company Act. Utility critics point to alternatives to central plant construction with cogeneration and small power generation. 2 figures

Nano-material aspects of shock absorption in bone joints.

Science.gov (United States)

Tributsch, H; Copf, F; Copf, P; Hindenlang, U; Niethard, F U; Schneider, R

2010-01-01

This theoretical study is based on a nano-technological evaluation of the effect of pressure on the composite bone fine structure. It turned out, that the well known macroscopic mechano-elastic performance of bones in combination with muscles and tendons is just one functional aspect which is critically supported by additional micro- and nano- shock damping technology aimed at minimising local bone material damage within the joints and supporting spongy bone material. The identified mechanisms comprise essentially three phenomena localised within the three-dimensional spongy structure with channels and so called perforated flexible tensulae membranes of different dimensions intersecting and linking them. Kinetic energy of a mechanical shock may be dissipated within the solid-liquid composite bone structure into heat via the generation of quasi-chaotic hydromechanic micro-turbulence. It may generate electro-kinetic energy in terms of electric currents and potentials. And the resulting specific structural and surface electrochemical changes may induce the compressible intra-osseal liquid to build up pressure dependent free chemical energy. Innovative bone joint prostheses will have to consider and to be adapted to the nano-material aspects of shock absorption in the operated bones.

Shock Producers and Shock Absorbers in the Crisis

OpenAIRE

Sinn, Hans-Werner

2009-01-01

It is not surprising that the U.S. has been by far the world’s largest shock producer in this crisis. The big shock absorbers on the other hand were Japan, Russia and Germany, whose exports shrank more than their imports.

Shock loading predictions from application of indicial theory to shock-turbulence interactions

Science.gov (United States)

Keefe, Laurence R.; Nixon, David

1991-01-01

A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

Optimal control of transient processes in an oscillating system with an electrorheological shock-absorber

Energy Technology Data Exchange (ETDEWEB)

Reizina, G N [National Technical University, 65 Nezavisimosti Avenue, Minsk, 220013 (Belarus); Korobko, E V; Bilyk, V A [Luikov Heat and Mass Transfer Institute of NASB, 15 P Brovki Street, Minsk, 220072 (Belarus); Efremov, V L; Binshtok, A E [Minsk Wheel Tractor Plant, 150 Partizanskii Avenue, Minsk, 220021 (Belarus)], E-mail: eva@itmo.by

2009-02-01

The problem of optimal control of the oscillation of a driver's seat with ER shock absorber is discussed in application to vehicles based on the principle of maximum. Coordinates of a vector of the control parameter and vertical motions of a seat are obtained. Test experimental investigations on working regimes for the driver's seat model depending on the controlling impact of the electrical signal (the intensity of the electric field) were performed.

Loss Aversion and Time-Differentiated Electricity Pricing

Energy Technology Data Exchange (ETDEWEB)

Spurlock, C. Anna [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-06-01

I develop a model of loss aversion over electricity expenditure, from which I derive testable predictions for household electricity consumption while on combination time-of-use (TOU) and critical peak pricing (CPP) plans. Testing these predictions results in evidence consistent with loss aversion: (1) spillover effects - positive expenditure shocks resulted in significantly more peak consumption reduction for several weeks thereafter; and (2) clustering - disproportionate probability of consuming such that expenditure would be equal between the TOUCPP or standard flat-rate pricing structures. This behavior is inconsistent with a purely neoclassical utility model, and has important implications for application of time-differentiated electricity pricing.

Gravitational shock waves and extreme magnetomaterial shock waves

International Nuclear Information System (INIS)

Lichnerowicz, Andre.

1975-01-01

Within an astrophysical context corresponding to high densities, a self-gravitating model is studied, which is the set of an extreme material medium of infinite conductivity and of a magnetic field. Corresponding shock waves generate necessarily, in general, gravitational shock waves [fr

Attentional Bias for Uncertain Cues of Shock in Human Fear Conditioning: Evidence for Attentional Learning Theory

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Stephan Koenig

2017-05-01

Full Text Available We conducted a human fear conditioning experiment in which three different color cues were followed by an aversive electric shock on 0, 50, and 100% of the trials, and thus induced low (L, partial (P, and high (H shock expectancy, respectively. The cues differed with respect to the strength of their shock association (L < P < H and the uncertainty of their prediction (L < P > H. During conditioning we measured pupil dilation and ocular fixations to index differences in the attentional processing of the cues. After conditioning, the shock-associated colors were introduced as irrelevant distracters during visual search for a shape target while shocks were no longer administered and we analyzed the cues’ potential to capture and hold overt attention automatically. Our findings suggest that fear conditioning creates an automatic attention bias for the conditioned cues that depends on their correlation with the aversive outcome. This bias was exclusively linked to the strength of the cues’ shock association for the early attentional processing of cues in the visual periphery, but additionally was influenced by the uncertainty of the shock prediction after participants fixated on the cues. These findings are in accord with attentional learning theories that formalize how associative learning shapes automatic attention.

Anaesthetic and other treatments of shell shock: World War I and beyond.

Science.gov (United States)

McKenzie, A G

2012-03-01

Post-traumatic stress disorder (PTSD) is an important health risk factor for military personnel deployed in modern warfare. In World War I this condition (then known as shell shock or 'neurasthenia') was such a problem that 'forward psychiatry' was begun by French doctors in 1915. Some British doctors tried general anaesthesia as a treatment (ether and chloroform), while others preferred application of electricity. Four British 'forward psychiatric units' were set up in 1917. Hospitals for shell shocked soldiers were also established in Britain, including (for officers) Craiglockhart War Hospital in Edinburgh; patients diagnosed to have more serious psychiatric conditions were transferred to the Royal Edinburgh Asylum. Towards the end of 1918 anaesthetic and electrical treatments of shell shock were gradually displaced by modified Freudian methods psychodynamic intervention. The efficacy of 'forward psychiatry' was controversial. In 1922 the War Office produced a report on shell shock with recommendations for prevention of war neurosis. However, when World War II broke out in 1939, this seemed to have been ignored. The term 'combat fatigue' was introduced as breakdown rates became alarming, and then the value of pre-selection was recognised. At the Maudsley Hospital in London in 1940 barbiturate abreaction was advocated for quick relief from severe anxiety and hysteria, using i.v. anaesthetics: Somnifaine, paraldehyde, Sodium Amytal. 'Pentothal narcosis' and 'narco-analysis' were adopted by British and American military psychiatrists. However, by 1945 medical thinking gradually settled on the same approaches that had seemed to be effective in 1918. The term PTSD was introduced in 1980. In the UK the National Institute for Health and Clinical Excellence (NICE) guidelines for management (2005) recommend trauma-focussed Cognitive Behavioural Therapy and consideration of antidepressants.

One-chip Integrated Module of MEMS Shock Sensor and Sensing Amplifier LSI using Pseudo-SOC Technology

Science.gov (United States)

Iida, Atsuko; Onozuka, Yutaka; Nishigaki, Michihiko; Yamada, Hiroshi; Funaki, Hideyuki; Itaya, Kazuhiko

We have been developing the pseudo-SOC technology for one-chip module integration of heterogeneous devices that realizes high electrical performance and high density of devices embodying the advantages of both SOC technology and SIP technology. Especially, this technology is available for MEMS-LSI integration. We developed a 0.2mm-thickness one-chip module integrating a MEMS shock sensor and a sensing amplifier LSI by applying this technology. The MEMS shock sensor and the sensing amplifier LSI were connected by high-rigidity epoxy resin optimized the material constants to reduce the stress and the warpage resulting from resin shrinkage due to curing. Then the planar insulating layer and the redistributed conducting layer were formed on it for the global layer. The MEMS shock sensor was preformed to be modularized with a glass cap. Electrical contacts were achieved by bonding of Au bumps on the MEMS fixed electrodes and via holes filled with Ag paste of the glass cap. Functional performance was confirmed by obtaining signal corresponding to the reference signal of the pick-up sensor. Furthermore, stress analysis was performed using the FEM model simulation considering the resin shrinkage.

Characterization of Exoelectrogenic Bacteria Enterobacter Strains Isolated from a Microbial Fuel Cell Exposed to Copper Shock Load

Science.gov (United States)

Feng, Cuijie; Li, Jiangwei; Qin, Dan; Chen, Lixiang; Zhao, Feng; Chen, Shaohua; Hu, Hongbo; Yu, Chang-Ping

2014-01-01

Microorganisms capable of generating electricity in microbial fuel cells (MFCs) have gained increasing interest. Here fourteen exoelectrogenic bacterial strains were isolated from the anodic biofilm in an MFC before and after copper (Cu) shock load by Hungate roll-tube technique with solid ferric (III) oxide as an electron acceptor and acetate as an electron donor. Phylogenetic analysis of the 16S rRNA gene sequences revealed that they were all closely related to Enterobacter ludwigii DSM 16688T within the Enterobacteriaceae family, although these isolated bacteria showed slightly different morphology before and after Cu shock load. Two representative strains R2B1 (before Cu shock load) and B4B2 (after Cu shock load) were chosen for further analysis. B4B2 is resistant to 200 mg L−1 of Cu(II) while R2B1 is not, which indicated the potential selection of the Cu shock load. Raman analysis revealed that both R2B1 and B4B2 contained c-type cytochromes. Cyclic voltammetry measurements revealed that strain R2B1 had the capacity to transfer electrons to electrodes. The experimental results demonstrated that strain R2B1 was capable of utilizing a wide range of substrates, including Luria-Bertani (LB) broth, cellulose, acetate, citrate, glucose, sucrose, glycerol and lactose to generate electricity, with the highest current density of 440 mA·m−2 generated from LB-fed MFC. Further experiments indicated that the bacterial cell density had potential correlation with the current density. PMID:25412475

Characterization of exoelectrogenic bacteria enterobacter strains isolated from a microbial fuel cell exposed to copper shock load.

Directory of Open Access Journals (Sweden)

Cuijie Feng

Full Text Available Microorganisms capable of generating electricity in microbial fuel cells (MFCs have gained increasing interest. Here fourteen exoelectrogenic bacterial strains were isolated from the anodic biofilm in an MFC before and after copper (Cu shock load by Hungate roll-tube technique with solid ferric (III oxide as an electron acceptor and acetate as an electron donor. Phylogenetic analysis of the 16S rRNA gene sequences revealed that they were all closely related to Enterobacter ludwigii DSM 16688T within the Enterobacteriaceae family, although these isolated bacteria showed slightly different morphology before and after Cu shock load. Two representative strains R2B1 (before Cu shock load and B4B2 (after Cu shock load were chosen for further analysis. B4B2 is resistant to 200 mg L-1 of Cu(II while R2B1 is not, which indicated the potential selection of the Cu shock load. Raman analysis revealed that both R2B1 and B4B2 contained c-type cytochromes. Cyclic voltammetry measurements revealed that strain R2B1 had the capacity to transfer electrons to electrodes. The experimental results demonstrated that strain R2B1 was capable of utilizing a wide range of substrates, including Luria-Bertani (LB broth, cellulose, acetate, citrate, glucose, sucrose, glycerol and lactose to generate electricity, with the highest current density of 440 mA·m-2 generated from LB-fed MFC. Further experiments indicated that the bacterial cell density had potential correlation with the current density.

Quasilinear simulations of interplanetary shocks and Earth's bow shock

Science.gov (United States)

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.

Electron Dropout Echoes Induced by Interplanetary Shock: A Statistical Study

Science.gov (United States)

Liu, Z.; Zong, Q.; Hao, Y.; Zhou, X.; Ma, X.; Liu, Y.

2017-12-01

"Electron dropout echo" as indicated by repeated moderate dropout and recovery signatures of the flux of energetic electron in the out radiation belt region has been investigated systematically. The electron dropout and its echoes are usually found for higher energy (> 300 keV) channels fluxes, whereas the flux enhancements are obvious for lower energy electrons simultaneously after the interplanetary shock arrives at the Earth's geosynchronous orbit. 104 dropout echo events have been found from 215 interplanetary shock events from 1998 to 2007 based on LANL satellite data. In analogy to substorm injections, these 104 events could be naturally divided into two categories: dispersionless (49 events) or dispersive (55 events) according to the energy dispersion of the initial dropout. It is found that locations of dispersionless events are distributed mainly in the duskside magnetosphere. Further, the obtained locations derived from dispersive events with the time-of-flight technique of the initial dropout regions are mainly located at the duskside as well. Statistical studies have shown that the effect of shock normal, interplanetary magnetic field Bz and solar wind dynamic pressure may be insignificant to these electron dropout events. We suggest that the electric field impulse induced by the IP shock produces a more pronounced inward migration of electrons at the dusk side, resulting in the observed dusk-side moderate dropout of electron flux and its consequent echoes.

Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals

Science.gov (United States)

Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

1983-01-01

ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.

Study on Exploding Wire Compression for Evaluating Electrical Conductivity in Warm-Dense Diamond-Like-Carbon

International Nuclear Information System (INIS)

Sasaki, Toru; Takahashi, Kazumasa; Kudo, Takahiro; Kikuchi, Takashi; Aso, Tsukasa; Harada, Nob.; Fujioka, Shinsuke; Horioka, Kazuhiko

2016-01-01

To improve a coupling efficiency for the fast ignition scheme of the inertial confinement fusion, fast electron behaviors as a function of an electrical conductivity are required. To evaluate the electrical conductivity for low-Z materials as a diamond-like-carbon (DLC), we have proposed a concept to investigate the properties of warm dense matter (WDM) by using pulsed-power discharges. The concept of the evaluation of DLC for WDM is a shock compression driven by an exploding wire discharge with confined by a rigid capillary. The qualitatively evaluation of the electrical conductivity for the WDM DLC requires a small electrical conductivity of the exploding wire. To analyze the electrical conductivity of exploding wire, we have demonstrated an exploding wire discharge in water for gold. The results indicated that the electrical conductivity of WDM gold for 5000 K of temperature has an insulator regime. It means that the shock compression driven by the exploding wire discharge with confined by the rigid capillary is applied for the evaluation of electrical conductivity for WDM DLC. (paper)

Are Credit Shocks Supply or Demand Shocks?

OpenAIRE

Bijapur, Mohan

2013-01-01

This paper provides new insights into the relationship between the supply of credit and the macroeconomy. We present evidence that credit shocks constitute shocks to aggregate supply in that they have a permanent effect on output and cause inflation to rise in the short term. Our results also suggest that the effects on aggregate supply have grown stronger in recent decades.

Miniature shock tube for laser driven shocks.

Science.gov (United States)

Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

2010-02-01

We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

General Physical Problems Related to MHD. Shock Tubes. Introduction to Papers in Section 1-b

Energy Technology Data Exchange (ETDEWEB)

NONE

1966-10-15

The papers which will be considered here are Nos. SM-74/26, 134, 172, 182 and 219. Each of the five papers will be discussed in turn, but before beginning this discussion, some general comments concerning shock tube studies of MHD generator plasmas seem in order. There is little doubt that the shock tube is an excellent facility-for the study of the basic processes which occur in the bulk of the plasma. It provides a large flow of uniform plasma with well-controlled properties. Because of the very short operating times, the materials problems, which plague continuously operating facilities, are eliminated. Depending upon the mode of operation of the shock tube, the gas dynamic conditions of an MHD generator may also be simulated more or less well. Three different modes have been used by the authors of the present papers. Abbas and Howatson have carried out their measurements in the driver plasma of an electrical shock tube. Both Zauderer and Mori, Kawada, Yamamoto and Imani have used the more conventional technique of experimenting in the plasma produced by the incident shock. Louis uses the plasma produced by reflection of the shock wave from the tube-end as a plasma source for the MHD channel.

Radiation- and pair-loaded shocks

Science.gov (United States)

Lyutikov, Maxim

2018-06-01

We consider the structure of mildly relativistic shocks in dense media, taking into account the radiation and pair loading, and diffusive radiation energy transfer within the flow. For increasing shock velocity (increasing post-shock temperature), the first important effect is the efficient energy redistribution by radiation within the shock that leads to the appearance of an isothermal jump, whereby the flow reaches the final state through a discontinuous isothermal transition. The isothermal jump, on scales much smaller than the photon diffusion length, consists of a weak shock and a quick relaxation to the isothermal conditions. Highly radiation-dominated shocks do not form isothermal jump. Pair production can mildly increase the overall shock compression ratio to ≈10 (4 for matter-dominated shocks and 7 of the radiation-dominated shocks).

INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

Directory of Open Access Journals (Sweden)

P. V. Bulat

2015-05-01

Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

Shock/shock interactions between bodies and wings

Directory of Open Access Journals (Sweden)

Gaoxiang XIANG

2018-02-01

Full Text Available This paper examines the Shock/Shock Interactions (SSI between the body and wing of aircraft in supersonic flows. The body is simplified to a flat wedge and the wing is assumed to be a sharp wing. The theoretical spatial dimension reduction method, which transforms the 3D problem into a 2D one, is used to analyze the SSI between the body and wing. The temperature and pressure behind the Mach stem induced by the wing and body are obtained, and the wave configurations in the corner are determined. Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative (NND finite difference scheme. Good agreements between the theoretical and numerical results are obtained. Additionally, the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically. The influences of wedge angle are significant, whereas the effects of sweep angle on wave configurations are negligible. This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows. Keywords: Body and wing, Flow field, Hypersonic flow, Shock/shock interaction, Wave configurations

Thermal and Arc Flash Analysis of Electric Motor Drives in Distribution Networks

OpenAIRE

Nikolovski, Srete; Mlakić, Dragan; Alibašić, Emir

2017-01-01

The paper presents thermal analysis and arc flash analysis taking care of protection relays coordination settings for electric motor drives connected to the electrical network. Power flow analysis is performed to check if there are any voltage and loading violation conditions in the system. Fault analysis is performed to check the short circuit values and compute arc flash energy dissipated at industrial busbars to eliminate damage to electrical equipment and electrical shocks and hazard to p...

GYROSURFING ACCELERATION OF IONS IN FRONT OF EARTH's QUASI-PARALLEL BOW SHOCK

International Nuclear Information System (INIS)

Kis, Arpad; Lemperger, Istvan; Wesztergom, Viktor; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Khotyaintsev, Yuri V.; Dandouras, Iannis

2013-01-01

It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-parallel bow shock resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow shock and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.

STEREO interplanetary shocks and foreshocks

Energy Technology Data Exchange (ETDEWEB)

Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

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.

STEREO interplanetary shocks and foreshocks

International Nuclear Information System (INIS)

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

2013-01-01

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 θ Bn ∼20-86°. 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 ∼1 AU and have been producing suprathermal particles for a shorter time.

Short pulse duration shock initiation experiments plus ignition and growth modeling on Composition B

International Nuclear Information System (INIS)

May, Chadd M; Tarver, Craig M

2014-01-01

Composition B (63% RDX, 36% TNT, 1% wax) is still a widely used energetic material whose shock initiation characteristics are necessary to understand. It is now possible to shock initiate Composition B and other secondary explosives at diameters well below their characteristic failure diameters for unconfined self-sustaining detonation. This is done using very high velocity, very thin, small diameter flyer plates accelerated by electric or laser power sources. Recently experimental detonation versus failure to detonate threshold flyer velocity curves for Composition B using several Kapton TM flyer thicknesses and diameters were measured. Flyer plates with diameters of 2 mm successfully detonated Composition B, which has a nominal failure diameter of 4.3 mm. The shock pressures required for these initiations are greater than the Chapman-Jouguet (C-J) pressure in self-sustaining Composition B detonation waves. The initiation process is two-dimensional, because both rear and side rarefactions can affect the shocked Composition B reaction rates. The Ignition and Growth reactive flow model for Composition B is extended to yield accurate simulations of this new threshold velocity data for various flyer thicknesses.

Shock Tube and Ballistic Range Facilities at NASA Ames Research Center

Science.gov (United States)

Grinstead, Jay H.; Wilder, Michael C.; Reda, Daniel C.; Cornelison, Charles J.; Cruden, Brett A.; Bogdanoff, David W.

2010-01-01

The Electric Arc Shock Tube (EAST) facility and the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center are described. These facilities have been in operation since the 1960s and have supported many NASA missions and technology development initiatives. The facilities have world-unique capabilities that enable experimental studies of real-gas aerothermal, gas dynamic, and kinetic phenomena of atmospheric entry.

Relativistic Shock Acceleration

International Nuclear Information System (INIS)

Duffy, P.; Downes, T.P.; Gallant, Y.A.; Kirk, J.G.

1999-01-01

In this paper we briefly review the basic theory of shock waves in relativistic hydrodynamics and magneto-hydrodynamics, emphasising some astrophysically interesting cases. We then present an overview of the theory of particle acceleration at such shocks describing the methods used to calculate the spectral indices of energetic particles. Recent results on acceleration at ultra-relativistic shocks are discussed. (author)

On the electron-ion temperature ratio established by collisionless shocks

Science.gov (United States)

Vink, Jacco; Broersen, Sjors; Bykov, Andrei; Gabici, Stefano

2015-07-01

Astrophysical shocks are often collisionless shocks, in which the changes in plasma flow and temperatures across the shock are established not through Coulomb interactions, but through electric and magnetic fields. An open question about collisionless shocks is whether electrons and ions each establish their own post-shock temperature (non-equilibration of temperatures), or whether they quickly equilibrate in the shock region. Here we provide a simple, thermodynamic, relation for the minimum electron-ion temperature ratios that should be expected as a function of Mach number. The basic assumption is that the enthalpy-flux of the electrons is conserved separately, but that all particle species should undergo the same density jump across the shock, in order for the plasma to remain charge neutral. The only form of additional electron heating that we allow for is adiabatic heating, caused by the compression of the electron gas. These assumptions result in an analytic treatment of expected electron-ion temperature ratio that agrees with observations of collisionless shocks: at low sonic Mach numbers, Ms ≲ 2, the electron-ion temperature ratio is close to unity, whereas for Mach numbers above Ms ≈ 60 the electron-ion temperature ratio asymptotically approaches a temperature ratio of Te/Ti = me/ ⟨ mi ⟩. In the intermediate Mach number range the electron-ion temperature ratio scales as Te/Ti ∝ Ms-2. In addition, we calculate the electron-ion temperature ratios under the assumption of adiabatic heating of the electrons only, which results in a higher electron-ion temperature ratio, but preserves the Te/Ti ∝ Ms-2 scaling. We also show that for magnetised shocks the electron-ion temperature ratio approaches the asymptotic value Te/Ti = me/ ⟨ mi ⟩ for lower magnetosonic Mach numbers (Mms), mainly because for a strongly magnetised shock the sonic Mach number is larger than the magnetosonic Mach number (Mms ≤ Ms). The predicted scaling of the electron

Electrical cardioversion

Science.gov (United States)

Sucu, Murat; Davutoglu, Vedat; Ozer, Orhan

2009-01-01

External electrical cardioversion was first performed in the 1950s. Urgent or elective cardioversions have specific advantages, such as termination of atrial and ventricular tachycardia and recovery of sinus rhythm. Electrical cardioversion is life-saving when applied in urgent circumstances. The succcess rate is increased by accurate tachycardia diagnosis, careful patient selection, adequate electrode (paddles) application, determination of the optimal energy and anesthesia levels, prevention of embolic events and arrythmia recurrence and airway conservation while minimizing possible complications. Potential complications include ventricular fibrillation due to general anesthesia or lack of synchronization between the direct current (DC) shock and the QRS complex, thromboembolus due to insufficient anticoagulant therapy, non-sustained VT, atrial arrhythmia, heart block, bradycardia, transient left bundle branch block, myocardial necrosis, myocardial dysfunction, transient hypotension, pulmonary edema and skin burn. Electrical cardioversion performed in patients with a pacemaker or an incompatible cardioverter defibrillator may lead to dysfunction, namely acute or chronic changes in the pacing or sensitivity threshold. Although this procedure appears fairly simple, serious consequences might occur if inappropriately performed. PMID:19448376

On possible structures of normal ionizing shock waves in electromagnetic shock tubes

International Nuclear Information System (INIS)

Liberman, M.A.; Synakh, V.S.; Zakajdakhov, V.V.; Velikovich, A.L.

1982-01-01

The problem of possible structures of normal ionizing shock waves is studied. On the basis of the general theory of ionizing shock waves in magnetic fields, a similarity solution of the piston problem for an impenetrable piston and a magnetic piston is described and a numerical solution of the non-stationary piston problem is obtained. It is shown that precursor photo-ionization of the neutral gas by the radiation of the shock-heated gas is the dominant factor in shaping normal ionizing shock structures. In particular, it is shown that the strong overheating of atoms and ions in shock fronts is due to the tensor form of Ohm's law in the precursor region. (author)

Multiple spacecraft observations of interplanetary shocks: four spacecraft determination of shock normals

International Nuclear Information System (INIS)

Russell, C.T.; Mellott, M.M.; Smith, E.J.; King, J.H.

1983-01-01

ISEE 1,2,3 IMP8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for furture techniques. When the angle between upstream and downstream magnetic field is greater than 20, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, we recommend using overdetermined shock normal solutions whenever possible, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints

Cells exposed to nanosecond electrical pulses exhibit biomarkers of mechanical stress

Science.gov (United States)

Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Moen, Erick K.; Glickman, Randolph D.

2015-03-01

Exposure of cells to very short (stressors on a cell, including electrical, electro-chemical, and mechanical stress. Thus, nsEP exposure is not a "clean" insult, making determination of the mechanism of nanoporation quite difficult. We hypothesize that nsEP exposure creates acoustic shock waves capable of causing nanoporation. Microarray analysis of primary adult human dermal fibroblasts (HDFa) exposed to nsEP, indicated several genes associated with mechanical stress were selectively upregulated 4 h post exposure. The idea that nanoporation is caused by external mechanical force from acoustic shock waves has, to our knowledge, not been investigated. This work will critically challenge the existing paradigm that nanoporation is caused solely by an electric-field driven event and could provide the basis for a plausible explanation for electroporation.

Shock absorber

International Nuclear Information System (INIS)

Nemeth, J.D.

1981-01-01

A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

System Shock: The Archetype of Operational Shock

Science.gov (United States)

2017-05-25

the battle space. They can also facilitate a much greater understanding of the variables involved in each party’s decision - making process. However...system shock nests within current US Army Unified Land Operations doctrine. In order to test the utility of system shock theory to Gray Zone...23 Neil E. Harrison, “Thinking about the World We Make ” in Chaos Theory in the Social Sciences: Foundations and Applications

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Development and performance evaluation of an electromagnetic-type shock wave generator for lipolysis

Energy Technology Data Exchange (ETDEWEB)

Liang, S. M., E-mail: liangsm@cc.feu.edu.tw; Yang, Z. Y. [Department of Industrial Design, Far East University, No. 49, Zhonghua Road, Xinshi District, Tainan City 744, Taiwan (China); Chang, M. H. [Department of Aeronautics and Astronautics, National Cheng Kung University, No. 1, University Road, East District, Tainan City 701, Taiwan (China)

2014-01-15

This study aims at the design and development of electromagnetic-type intermittent shock wave generation in a liquid. The shock wave generated is focused at a focal point through an acoustic lens. This hardware device mainly consists of a full-wave bridge rectifier, 6 capacitors, a spark gap, and a flat coil. A metal disk is mounted in a liquid-filled tube and is placed in close proximity to the flat coil. Due to the repulsive force existing between the coil and disk shock waves are generated, while an eddy current is induced in the metal disk. Some components and materials associated with the device are also described. By increasing the capacitance content to enhance electric energy level, a highly focused pressure can be achieved at the focal point through an acoustic lens in order to lyse fat tissue. Focused pressures were measured at the focal point and its vicinity for different operation voltages. The designed shock wave generator with an energy intensity of 0.0016 mJ/mm{sup 2} (at 4 kV) and 2000 firings or higher energy intensities with 1000 firings is found to be able to disrupt pig fat tissue.

Development and performance evaluation of an electromagnetic-type shock wave generator for lipolysis.

Science.gov (United States)

Liang, S M; Chang, M H; Yang, Z Y

2014-01-01

This study aims at the design and development of electromagnetic-type intermittent shock wave generation in a liquid. The shock wave generated is focused at a focal point through an acoustic lens. This hardware device mainly consists of a full-wave bridge rectifier, 6 capacitors, a spark gap, and a flat coil. A metal disk is mounted in a liquid-filled tube and is placed in close proximity to the flat coil. Due to the repulsive force existing between the coil and disk shock waves are generated, while an eddy current is induced in the metal disk. Some components and materials associated with the device are also described. By increasing the capacitance content to enhance electric energy level, a highly focused pressure can be achieved at the focal point through an acoustic lens in order to lyse fat tissue. Focused pressures were measured at the focal point and its vicinity for different operation voltages. The designed shock wave generator with an energy intensity of 0.0016 mJ/mm(2) (at 4 kV) and 2000 firings or higher energy intensities with 1000 firings is found to be able to disrupt pig fat tissue.

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

Energy Technology Data Exchange (ETDEWEB)

Giacalone, J. [Department of Planetary Sciences, University of Arizona, Tucson, AZ (United States)

2017-10-20

We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean and an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell’s equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere’s equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles “collect” at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highest-energy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.

Flow processes in electric discharge drivers

Science.gov (United States)

Baganoff, D.

1975-01-01

The performance of an electric discharge shock tube is discussed from the point of view that the conditions at the sonic station are the primary controlling variables (likewise in comparing designs), and that the analysis of the flow on either side of the sonic station should be done separately. The importance of considering mass-flow rate in matching a given driver design to the downstream flow required for a particular shock-wave speed is stressed. It is shown that a driver based on the principle of liquid injection (of H2) is superior to one based on the Ludwieg tube, because of the greater mass-flow rate and the absence of a massive diaphragm.

Electrical storm after CRT implantation treated by AV delay optimization.

Science.gov (United States)

Combes, Nicolas; Marijon, Eloi; Boveda, Serge; Albenque, Jean-Paul

2010-02-01

We present a case of symptomatic ischemic heart failure with an indication for cardiac resynchronization and implantable cardiac defibrillator therapy in primary prevention. After implantation, the patient developed a severe electrical storm with multiple shocks. Hemodynamic improvement based only on AV delay, guided by echocardiography and ECG, brought about a dramatic improvement in the situation. We discuss the pathophysiology of electrical storm occurring immediately after LV pacing.

Dynamics of particles accelerated by head-on collisions of two magnetized plasma shocks

Science.gov (United States)

Takeuchi, Satoshi

2018-02-01

A kinetic model of the head-on collision of two magnetized plasma shocks is analyzed theoretically and in numerical calculations. When two plasmas with anti-parallel magnetic fields collide, they generate magnetic reconnection and form a motional electric field at the front of the collision region. This field accelerates the particles sandwiched between both shock fronts to extremely high energy. As they accelerate, the particles are bent by the transverse magnetic field crossing the magnetic neutral sheet, and their energy gains are reduced. In the numerical calculations, the dynamics of many test particles were modeled through the relativistic equations of motion. The attainable energy gain was obtained by multiplying three parameters: the propagation speed of the shock, the magnitude of the magnetic field, and the acceleration time of the test particle. This mechanism for generating high-energy particles is applicable over a wide range of spatial scales, from laboratory to interstellar plasmas.

Effects of response-shock interval and shock intensity on free-operant avoidance responding in the pigeon1

Science.gov (United States)

Klein, Marty; Rilling, Mark

1972-01-01

Two experiments investigated free-operant avoidance responding with pigeons using a treadle-pressing response. In Experiment I, pigeons were initially trained on a free-operant avoidance schedule with a response-shock interval of 32 sec and a shock-shock interval of 10 sec, and were subsequently exposed to 10 values of the response-shock parameter ranging from 2.5 to 150 sec. The functions relating response rate to response-shock interval were similar to the ones reported by Sidman in his 1953 studies employing rats, and were independent of the order of presentation of the response-shock values. Shock rates decreased as response-shock duration increased. In Experiment II, a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 5 sec was used, and shock intensities were varied over five values ranging from 2 to 32 mA. Response rates increased markedly as shock intensity increased from 2 to 8 mA, but rates changed little with further increases in shock intensity. Shock rates decreased as intensity increased from 2 to 8 mA, and showed little change as intensity increased from 8 to 32 mA. PMID:4652617

External cardiac compression may be harmful in some scenarios of pulseless electrical activity.

Science.gov (United States)

Hogan, T S

2012-10-01

Pulseless electrical activity occurs when organised or semi-organised electrical activity of the heart persists but the product of systemic vascular resistance and the increase in systemic arterial flow generated by the ejection of the left venticular stroke volume is not sufficient to produce a clinically detectable pulse. Pulseless electrical activity encompasses a very heterogeneous variety of severe circulatory shock states ranging in severity from pseudo-cardiac arrest to effective cardiac arrest. Outcomes of cardiopulmonary resuscitation for pulseless electrical activity are generally poor. Impairment of cardiac filling is the limiting factor to cardiac output in many scenarios of pulseless electrical activity, including extreme vasodilatory shock states. There is no evidence that external cardiac compression can increase cardiac output when impaired cardiac filling is the limiting factor to cardiac output. If impaired cardiac filling is the limiting factor to cardiac output and the heart is effectively ejecting all the blood returning to it, then external cardiac compression can only increase cardiac output if it increases venous return and cardiac filling. Repeated cardiac compression asynchronous with the patient's cardiac cycle and raised mean intrathoracic pressure due to chest compression can be expected to reduce rather than to increase cardiac filling and therefore to reduce rather than to increase cardiac output in such circumstances. The hypothesis is proposed that the performance of external cardiac compression will have zero or negative effect on cardiac output in pulseless electrical activity when impaired cardiac filling is the limiting factor to cardiac output. External cardiac compression may be both directly and indirectly harmful to significant sub-groups of patients with pulseless electrical activity. We have neither evidence nor theory to provide comfort that external cardiac compression is not harmful in many scenarios of pulseless

External cardiac compression may be harmful in some scenarios of pulseless electrical activity.

LENUS (Irish Health Repository)

Hogan, T S

2012-10-01

Pulseless electrical activity occurs when organised or semi-organised electrical activity of the heart persists but the product of systemic vascular resistance and the increase in systemic arterial flow generated by the ejection of the left venticular stroke volume is not sufficient to produce a clinically detectable pulse. Pulseless electrical activity encompasses a very heterogeneous variety of severe circulatory shock states ranging in severity from pseudo-cardiac arrest to effective cardiac arrest. Outcomes of cardiopulmonary resuscitation for pulseless electrical activity are generally poor. Impairment of cardiac filling is the limiting factor to cardiac output in many scenarios of pulseless electrical activity, including extreme vasodilatory shock states. There is no evidence that external cardiac compression can increase cardiac output when impaired cardiac filling is the limiting factor to cardiac output. If impaired cardiac filling is the limiting factor to cardiac output and the heart is effectively ejecting all the blood returning to it, then external cardiac compression can only increase cardiac output if it increases venous return and cardiac filling. Repeated cardiac compression asynchronous with the patient\\'s cardiac cycle and raised mean intrathoracic pressure due to chest compression can be expected to reduce rather than to increase cardiac filling and therefore to reduce rather than to increase cardiac output in such circumstances. The hypothesis is proposed that the performance of external cardiac compression will have zero or negative effect on cardiac output in pulseless electrical activity when impaired cardiac filling is the limiting factor to cardiac output. External cardiac compression may be both directly and indirectly harmful to significant sub-groups of patients with pulseless electrical activity. We have neither evidence nor theory to provide comfort that external cardiac compression is not harmful in many scenarios of pulseless

Diaphragmless shock wave generators for industrial applications of shock waves

Science.gov (United States)

Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

2011-06-01

The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

Impact of Isothermal Aging and Testing Temperature on Large Flip-Chip BGA Interconnect Mechanical Shock Performance

Science.gov (United States)

Lee, Tae-Kyu; Chen, Zhiqiang; Guirguis, Cherif; Akinade, Kola

2017-10-01

The stability of solder interconnects in a mechanical shock environment is crucial for large body size flip-chip ball grid array (FCBGA) electronic packages. Additionally, the junction temperature increases with higher electric power condition, which brings the component into an elevated temperature environment, thus introducing another consideration factor for mechanical stability of interconnection joints. Since most of the shock performance data available were produced at room temperature, the effect of elevated temperature is of interest to ensure the reliability of the device in a mechanical shock environment. To achieve a stable␣interconnect in a dynamic shock environment, the interconnections must tolerate mechanical strain, which is induced by the shock wave input and reaches the particular component interconnect joint. In this study, large body size (52.5 × 52.5 mm2) FCBGA components assembled on 2.4-mm-thick boards were tested with various isothermal pre-conditions and testing conditions. With a heating element embedded in the test board, a test temperature range from room temperature to 100°C was established. The effects of elevated temperature on mechanical shock performance were investigated. Failure and degradation mechanisms are identified and discussed based on the microstructure evolution and grain structure transformations.

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

Energy Technology Data Exchange (ETDEWEB)

Watson, S [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); MacPherson, W N [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Barton, J S [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Jones, J D C [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Tyas, A [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Pichugin, A V [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Hindle, A [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Parkes, W [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom); Dunare, C [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom); Stevenson, T [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom)

2005-01-01

We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1mm{sup 2} in overall cross-section with rise times in the {mu}s regime and pressure ranges typically 600 kPa. Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Provisional results from blast tests will be presented in which up to 6 sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

International Nuclear Information System (INIS)

Watson, S; MacPherson, W N; Barton, J S; Jones, J D C; Tyas, A; Pichugin, A V; Hindle, A; Parkes, W; Dunare, C; Stevenson, T

2005-01-01

We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1mm 2 in overall cross-section with rise times in the μs regime and pressure ranges typically 600 kPa. Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Provisional results from blast tests will be presented in which up to 6 sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front

Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

Science.gov (United States)

Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

1991-04-01

Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

Basic study on promotion of thawing frozen soil by shock loading

Directory of Open Access Journals (Sweden)

Toshiaki WATANABE

2008-06-01

Full Text Available The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. In the case of small processing area such as road repairing, frozen soil is thawed by using the heat of gas burner and/or the electric heater. It is not a suitable plan to apply these heating methods to agriculture, from the point of view enormous amount of processing area. Thawing technique for frozen soil is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. At first, we carried out experiments using a detonating fuse and ice block. The propagation process of shock wave into the ice block was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil.

Shock Isolation Elements Testing for High Input Loadings. Volume III. Mechanical Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*SPRINGS, (*SHOCK(MECHANICS), REDUCTION), TORSION BARS, ELASTOMERS, DAMPING, EQUATIONS OF MOTION, MODEL TESTS, TEST METHODS, NUCLEAR EXPLOSIONS, HARDENING.

PARTICLE ACCELERATION AT THE HELIOSPHERIC TERMINATION SHOCK WITH A STOCHASTIC SHOCK OBLIQUITY APPROACH

International Nuclear Information System (INIS)

Arthur, Aaron D.; Le Roux, Jakobus A.

2013-01-01

Observations by the plasma and magnetic field instruments on board the Voyager 2 spacecraft suggest that the termination shock is weak with a compression ratio of ∼2. However, this is contrary to the observations of accelerated particle spectra at the termination shock, where standard diffusive shock acceleration theory predicts a compression ratio closer to ∼2.9. Using our focused transport model, we investigate pickup proton acceleration at a stationary spherical termination shock with a moderately strong compression ratio of 2.8 to include both the subshock and precursor. We show that for the particle energies observed by the Voyager 2 Low Energy Charged Particle (LECP) instrument, pickup protons will have effective length scales of diffusion that are larger than the combined subshock and precursor termination shock structure observed. As a result, the particles will experience a total effective termination shock compression ratio that is larger than values inferred by the plasma and magnetic field instruments for the subshock and similar to the value predicted by diffusive shock acceleration theory. Furthermore, using a stochastically varying magnetic field angle, we are able to qualitatively reproduce the multiple power-law structure observed for the LECP spectra downstream of the termination shock

The cosmic-ray shock structure problem for relativistic shocks

Science.gov (United States)

Webb, G. M.

1985-01-01

The time asymptotic behaviour of a relativistic (parallel) shock wave significantly modified by the diffusive acceleration of cosmic-rays is investigated by means of relativistic hydrodynamical equations for both the cosmic-rays and thermal gas. The form of the shock structure equation and the dispersion relation for both long and short wavelength waves in the system are obtained. The dependence of the shock acceleration efficiency on the upstream fluid spped, long wavelength Mach number and the ratio N = P sub co/cP sub co+P sub go)(Psub co and P sub go are the upstream cosmic-ray and thermal gas pressures respectively) are studied.

Numerical Study of Shock Wave Attenuation in Two-Dimensional Ducts Using Solid Obstacles: How to Utilize Shock Focusing Techniques to Attenuate Shock Waves

Directory of Open Access Journals (Sweden)

Qian Wan

2015-04-01

Full Text Available Research on shock wave mitigation in channels has been a topic of much attention in the shock wave community. One approach to attenuate an incident shock wave is to use obstacles of various geometries arranged in different patterns. This work is inspired by the study from Chaudhuri et al. (2013, in which cylinders, squares and triangles placed in staggered and non-staggered subsequent columns were used to attenuate a planar incident shock wave. Here, we present numerical simulations using a different obstacle pattern. Instead of using a matrix of obstacles, an arrangement of square or cylindrical obstacles placed along a logarithmic spiral curve is investigated, which is motivated by our previous work on shock focusing using logarithmic spirals. Results show that obstacles placed along a logarithmic spiral can delay both the transmitted and the reflected shock wave. For different incident shock Mach numbers, away from the logarithmic spiral design Mach number, this shape is effective to either delay the transmitted or the reflected shock wave. Results also confirm that the degree of attenuation depends on the obstacle shape, effective flow area and obstacle arrangement, much like other obstacle configurations.

Electrical and hydrodynamic characterization of a high current pulsed arc

International Nuclear Information System (INIS)

Sousa Martins, R; Chemartin, L; Zaepffel, C; Lalande, Ph; Soufiani, A

2016-01-01

High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine–Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs. (paper)

Electrical and hydrodynamic characterization of a high current pulsed arc

Science.gov (United States)

Sousa Martins, R.; Chemartin, L.; Zaepffel, C.; Lalande, Ph; Soufiani, A.

2016-05-01

High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine-Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs.

STEREO Observations of Waves in the Ramp Regions of Interplanetary Shocks

Science.gov (United States)

Cohen, Z.; Breneman, A. W.; Cattell, C. A.; Davis, L.; Grul, P.; Kersten, K.; Wilson, L. B., III

2017-12-01

Determining the role of plasma waves in providing energy dissipation at shock waves is of long-standing interest. Interplanetary (IP) shocks serve as a large database of low Mach number shocks. We examine electric field waveforms captured by the Time Domain Sampler (TDS) on the STEREO spacecraft during the ramps of IP shocks, with emphasis on captures lasting 2.1 seconds. Previous work has used captures of shorter duration (66 and 131 ms on STEREO, and 17 ms on WIND), which allowed for observation of waves with maximum (minimum) frequencies of 125 kHz (15 Hz), 62.5 kHz (8 Hz), and 60 kHz (59 Hz), respectively. The maximum frequencies are comparable to 2-8 times the plasma frequency in the solar wind, enabling observation of Langmuir waves, ion acoustic, and some whistler-mode waves. The 2 second captures resolve lower frequencies ( few Hz), which allows us to analyze packet structure of the whistler-mode waves and some ion acoustic waves. The longer capture time also improves the resolvability of simultaneous wave modes and of waves with frequencies on the order of 10s of Hz. Langmuir waves, however, cannot be identified at this sampling rate, since the plasma frequency is usually higher than 3.9 kHz. IP shocks are identified from multiple databases (Helsinki heliospheric shock database at http://ipshocks.fi, and the STEREO level 3 shock database at ftp://stereoftp.nascom.nasa.gov/pub/ins_data/impact/level3/). Our analysis focuses on TDS captures in shock ramp regions, with ramp durations determined from magnetic field data taken at 8 Hz. Software is used to identify multiple wave modes in any given capture and classify waves as Langmuir, ion acoustic, whistler, lower hybrid, electron cyclotron drift instability, or electrostatic solitary waves. Relevant frequencies are determined from density and magnetic field data collected in situ. Preliminary results suggest that large amplitude (≥ 5 mV/m) ion acoustic waves are most prevalent in the ramp, in agreement with

Converging cylindrical shocks in ideal magnetohydrodynamics

KAUST Repository

Pullin, D. I.

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 = √μ0/p0 I/(2π) 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 then

Converging cylindrical shocks in ideal magnetohydrodynamics

International Nuclear Information System (INIS)

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

2014-01-01

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=√(μ 0 /p 0 ) I/(2 π) where I is the current, μ 0 is the permeability, and p 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 diverging magnetic field

Converging cylindrical shocks in ideal magnetohydrodynamics

Energy Technology Data Exchange (ETDEWEB)

Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

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

Converging cylindrical shocks in ideal magnetohydrodynamics

KAUST Repository

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

2014-01-01

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 = √μ0/p0 I/(2π) 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 then

Fuel coolant interaction experiment by direct electrical heating method

International Nuclear Information System (INIS)

Takeda, Tsuneo; Hirano, Kenmei

1979-01-01

In the PCM (Power Cooling Mismatch) experiments, the FCI (Fuel Coolant Interaction) test is one of necessary tests in order to predict various phenomena that occur during PCM in the core. A direct electrical heating method is used for the FCI tests for fuel pellet temperature of over 1000 0 C. Therefore, preheating is required before initiating the direct electrical heating. The fuel pin used in the FCI tests is typical LWR fuel element, which is surrounded by coolant water. It is undersirable to heat up the coolant water during preheating of the fuel pin. Therefore, a zirconia (ZrO 2 ) pellet which is similar to a UO 2 pellet in physical and chemical properties is used. Electric property (electric conductivity) of ZrO 2 is particularly suitable for direct electrical heating as in the case of UO 2 . In this experiment, ZrO 2 pellet (melting point 2500 0 C) melting was achieved by use of both preheating and direct electrical heating. Temperature changes of coolant and fuel surface, as well as the pressure change of coolant water, were measured. The molten fuel interacted with the coolant and generated shock waves. A portion of this molten fuel fragmented into small particles during this interaction. The peak pressure of the observed shock wave was about 35 bars. The damaged fuel pin was photographed after disassembly. This report shows the measured coolant pressure changes and the coolant temperature changes, as well as photographs of damaged fuel pin and fuel fragments. (author)

Phenomenological description of depoling current in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression: Relaxation model

Science.gov (United States)

Jiang, Dongdong; Du, Jinmei; Gu, Yan; Feng, Yujun

2012-05-01

By assuming a relaxation process for depolarization associated with the ferroelectric (FE) to antiferroelectric (AFE) phase transition in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression, we build a new model for the depoling current, which is different from both the traditional constant current source (CCS) model and the phase transition kinetics (PTK) model. The characteristic relaxation time and new-equilibrated polarization are dependent on both the shock pressure and electric field. After incorporating a Maxwell s equation, the relaxation model developed applies to all the depoling currents under short-circuit condition and high-impedance condition. Influences of shock pressure, load resistance, dielectric property, and electrical conductivity on the depoling current are also discussed. The relaxation model gives a good description about the suppressing effect of the self-generated electric field on the FE-to-AFE phase transition at low shock pressures, which cannot be described by the traditional models. After incorporating a time- and electric-field-dependent repolarization, this model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. Finally, we make the comparison between our relaxation model and the traditional CCS model and PTK model.

A shock surface geometry - The February 15-16, 1967, event. [solar flare associated interplanetary shock

Science.gov (United States)

Lepping, R. P.; Chao, J. K.

1976-01-01

An estimated shape is presented for the surface of the flare-associated interplanetary shock of February 15-16, 1967, as seen in the ecliptic-plane cross section. The estimate is based on observations by Explorer 33 and Pioneers 6 and 7. The estimated shock normal at the Explorer 33 position is obtained by a least-squares shock parameter-fitting procedure for that satellite's data; the shock normal at the Pioneer 7 position is found by using the magnetic coplanarity theorem and magnetic-field data. The average shock speed from the sun to each spacecraft is determined along with the local speed at Explorer 33 and the relations between these speeds and the position of the initiating solar flare. The Explorer 33 shock normal is found to be severely inclined and not typical of interplanetary shocks. It is shown that the curvature of the shock surface in the ecliptic plane near the earth-Pioneer 7 region is consistent with a radius of not more than 0.4 AU.

Pediatric Toxic Shock Syndrome

Directory of Open Access Journals (Sweden)

Jennifer Yee

2017-09-01

Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the diagnosis and management of a pediatric patient with toxic shock syndrome. The case is also appropriate for teaching of medical students and advanced practice providers, as well as a review of the principles of crisis resource management, teamwork, and communication. Introduction: Toxic shock syndrome is a low-frequency, high-acuity scenario requiring timely identification and aggressive management. If patients suffering from this condition are managed incorrectly, they may progress into multi-organ dysfunction and potentially death. Toxic shock syndrome has been associated with Streptococcus and Staphylococcus aureus (Staph. Approximately half of Staph cases are associated with menstruation, which was first described in the 1970s-1980s and was associated with the use of absorbent tampons.1 Group A Streptococcus may cause complications such as necrotizing fasciitis and gangrenous myositis.2 Pediatric patients may present critically ill from toxic shock syndrome. Providers need to perform a thorough history and physical exam to discern the source of infection. Management requires aggressive care with antibiotics and IV fluids. Objectives: By the end of this simulation session, the learner will be able to: 1 Recognize toxic shock syndrome. 2 Review the importance of a thorough physical exam. 3 Discuss management of toxic shock syndrome, including supportive care and the difference in antibiotic choices for streptococcal and staphylococcal toxic shock syndrome. 4 Appropriately disposition a patient suffering from toxic shock syndrome. 5 Communicate effectively with team members and nursing staff during a resuscitation of a critically ill patient. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on toxic shock syndrome.

Selfsimilar time dependent shock structures

International Nuclear Information System (INIS)

Beck, R.; Drury, L.O.

1985-01-01

Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The same argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions

Selfsimilar time dependent shock structures

Science.gov (United States)

Beck, R.; Drury, L. O.

1985-01-01

Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The ame argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions.

Over-the-road shock and vibration testing of the radioisotope thermoelectric generator transportation system

International Nuclear Information System (INIS)

Becker, D.L.

1997-01-01

Radioisotope Thermoelectric Generators (RTG) convert heat generated by radioactive decay into electricity through the use of thermocouples. The RTGs have a long operating life, are reasonably lightweight, and require little or no maintenance, which make them particularly attractive for use in spacecraft. However, because RTGs contain significant quantities of radioactive materials, normally plutonium-238 and its decay products, they must be transported in packages built in accordance with Title 10, Code of Federal Regulations, Part 71 (10 CFR 71). To meet these regulations, a RTG Transportation System (RTGTS) that fully complies with 10 CFR 71 has been developed, which protects RTGs from adverse environmental conditions during normal conditions of transport (e.g., shock, vibration, and heat). To ensure the protection of RTGs from shock and vibration loadings during transport, extensive over-the-road testing was conducted on the RTG'S to obtain real-time recordings of accelerations of the air-ride suspension system trailer floor, packaging, and support structure. This paper provides an overview of the RTG'S, a discussion of the shock and vibration testing, and a comparison of the test results to the specified shock response spectra and power spectral density acceleration criteria

Pulsed electrical discharges for medicine and biology techniques, processes, applications

CERN Document Server

Kolikov, Victor

2015-01-01

This book presents the application of pulsed electrical discharges in water and water dispersions of metal nanoparticles in medicine (surgery, dentistry, and oncology), biology, and ecology. The intensive electrical and shock waves represent a novel technique to destroy viruses and this way to  prepare anti-virus vaccines. The method of pulsed electrical discharges in water allows to decontaminate water from almost all known bacteria and spores of fungi being present in human beings. The nanoparticles used are not genotoxic and mutagenic. This book is useful for researchers and graduate students.

Inferring Pre-shock Acoustic Field From Post-shock Pitot Pressure Measurement

Science.gov (United States)

Wang, Jian-Xun; Zhang, Chao; Duan, Lian; Xiao, Heng; Virginia Tech Team; Missouri Univ of Sci; Tech Team

2017-11-01

Linear interaction analysis (LIA) and iterative ensemble Kalman method are used to convert post-shock Pitot pressure fluctuations to static pressure fluctuations in front of the shock. The LIA is used as the forward model for the transfer function associated with a homogeneous field of acoustic waves passing through a nominally normal shock wave. The iterative ensemble Kalman method is then employed to infer the spectrum of upstream acoustic waves based on the post-shock Pitot pressure measured at a single point. Several test cases with synthetic and real measurement data are used to demonstrate the merits of the proposed inference scheme. The study provides the basis for measuring tunnel freestream noise with intrusive probes in noisy supersonic wind tunnels.

Broadband Electromagnetic Emission from PZT Ferroelectric Ceramics after Shock Loading

Directory of Open Access Journals (Sweden)

Fiodoras ANISIMOVAS

2013-12-01

Full Text Available It was experimentally registered pulsed electromagnetic (EM radiation in frequency range higher than television one using wideband horns with coaxial and waveguide outputs. The EM radiation was received during shock loading of lead zirconate titanate (PZT ceramics cylinders in conventional piezoelectric ignition mechanisms. Digital oscilloscope allows registering whole series of EM pulses and each pulse from the series transmitted from horn antenna of (1 – 18 GHz operating band frequencies. There is (1 – 4 ms delay between the shock and the first pulse of the series. Duration of the series is about (3 – 4 ms. The PZT cylinders were cleaved along their axes and the surfaces formed in the process were investigated by scanning electron microscope. It was concluded that from electrical point of view PZT ceramics contain interacting subsystems. It was found that EM radiation spectrum of pulse detected by waveguide detector heads has harmonics reaching 80 GHz. Presence of harmonics higher than 20 GHz indicates on radiation due to deceleration of electrons emitted during the switching. The EM pulses in the series appear randomly and have different amplitudes which partly confirmed thesis on independent switching dynamics of small volumes governed by a local electric field.DOI: http://dx.doi.org/10.5755/j01.ms.19.4.3137

THE EFFECTS OF AREA CONTRACTION ON SHOCK WAVE STRENGTH AND PEAK PRESSURE IN SHOCK TUBE

Directory of Open Access Journals (Sweden)

A. M. Mohsen

2012-06-01

Full Text Available This paper presents an experimental investigation into the effects of area contraction on shock wave strength and peak pressure in a shock tube. The shock tube is an important component of the short duration, high speed fluid flow test facility, available at the Universiti Tenaga Nasional (UNITEN, Malaysia. The area contraction was facilitated by positioning a bush adjacent to the primary diaphragm section, which separates the driver and driven sections. Experimental measurements were performed with and without the presence of the bush, at various diaphragm pressure ratios, which is the ratio of air pressure between the driver (high pressure and driven (low pressure sections. The instantaneous static pressure variations were measured at two locations close to the driven tube end wall, using high sensitivity pressure sensors, which allow the shock wave strength, shock wave speed and peak pressure to be analysed. The results reveal that the area contraction significantly reduces the shock wave strength, shock wave speed and peak pressure. At a diaphragm pressure ratio of 10, the shock wave strength decreases by 18%, the peak pressure decreases by 30% and the shock wave speed decreases by 8%.

Structure of intermediate shocks and slow shocks in a magnetized plasma with heat conduction

International Nuclear Information System (INIS)

Tsai, C.L.; Wu, B.H.; Lee, L.C.

2005-01-01

The structure of slow shocks and intermediate shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. This study is an extension of an earlier work [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002)], in which the effects of heat conduction are examined for the case that the tangential magnetic fields on the two side of initial current sheet are exactly antiparallel (B y =0). For the B y =0 case, a pair of slow shocks is formed as the result of evolution of the initial current sheet, and each slow shock consists of two parts: the isothermal main shock and the foreshock. In the present paper, cases with B y ≠0 are also considered, in which the evolution process leads to the presence of an additional pair of time-dependent intermediate shocks (TDISs). Across the main shock of the slow shock, jumps in plasma density, velocity, and magnetic field are significant, but the temperature is continuous. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. In contrast to the earlier study, the foreshock is found to reach a steady state with a constant width in the slow shock frame. In cases with B y ≠0, the plasma density and pressure increase and the magnetic field decreases across TDIS. The TDIS initially can be embedded in the slow shock's foreshock structure, and then moves out of the foreshock region. With an increasing B y , the propagation speed of foreshock leading edge tends to decrease and the foreshock reaches its steady state at an earlier time. Both the pressure and temperature downstreams of the main shock decrease with increasing B y . The results can be applied to the shock heating in the solar corona and

Ion Thermalization and Electron Heating across Quasi-Perpendicular Shocks Observed by the MMS Mission

Science.gov (United States)

Chen, L. J.; Wilson, L. B., III; Wang, S.; Bessho, N.; Figueroa-Vinas, A.; Lai, H.; Russell, C. T.; Schwartz, S. J.; Hesse, M.; Moore, T. E.; Burch, J.; Gershman, D. J.; Giles, B. L.; Torbert, R. B.; Ergun, R.; Dorelli, J.; Strangeway, R. J.; Paterson, W. R.; Lavraud, B.; Khotyaintsev, Y. V.

2017-12-01

Collisionless shocks often involve intense plasma heating in space and astrophysical systems. Despite decades of research, a number of key questions concerning electron and ion heating across collisionless shocks remain unanswered. We `image' 20 supercritical quasi-perpendicular bow shocks encountered by the Magnetospheric Multiscale (MMS) spacecraft with electron and ion distribution functions to address how ions are thermalized and how electrons are heated. The continuous burst measurements of 3D plasma distribution functions from MMS reveal that the primary thermalization phase of ions occurs concurrently with the main temperature increase of electrons as well as large-amplitude wave fluctuations. Approaching the shock from upstream, the ion temperature (Ti) increases due to the reflected ions joining the incoming solar wind population, as recognized by prior studies, and the increase of Ti precedes that of the electrons. Thermalization in the form of merging between the decelerated solar wind ions and the reflected component often results in a decrease in Ti. In most cases, the Ti decrease is followed by a gradual increase further downstream. Anisotropic, energy-dependent, and/or nongyrotropic electron energization are observed in association with large electric field fluctuations in the main electron temperature (Te) gradient, motivating a renewed scrutiny of the effects from the electrostatic cross-shock potential and wave fluctuations on electron heating. Particle-in-cell (PIC) simulations are carried out to assist interpretations of the MMS observations. We assess the roles of instabilities and the cross-shock potential in thermalizing ions and heating electrons based on the MMS measurements and PIC simulation results. Challenges will be posted for future computational studies and laboratory experiments on collisionless shocks.

Shock waves in gas and plasma

International Nuclear Information System (INIS)

Niu, K.

1996-01-01

A shock wave is a discontinuous surface that connects supersonic flow with subsonic flow. After a shock wave, flow velocity is reduced, and pressure and temperature increase; entropy especially increases across a shock wave. Therefore, flow is in nonequilibrium, and irreversible processes occur inside the shock layer. The thickness of a shock wave in neutral gas is of the order of the mean free path of the fluid particle. A shock wave also appears in magnetized plasma. Provided that when the plasma flow is parallel to the magnetic field, a shock wave appears if the governing equation for velocity potential is in hyperbolic type in relation with the Mach number and the Alfven number. When the flow is perpendicular to the magnetic field, the Maxwell stress, in addition to the pressure, plays a role in the shock wave in plasma. When the plasma temperature is so high, as the plasma becomes collision-free, another type of shock wave appears. In a collision-free shock wave, gyromotions of electrons around the magnetic field lines cause the shock formation instead of collisions in a collision-dominant plasma or neutral gas. Regardless of a collision-dominant or collision-free shock wave, the fluid that passes through the shock wave is heated in addition to being compressed. In inertial confinement fusion, the fuel must be compressed. Really, implosion motion performs fuel compression. A shock wave, appearing in the process of implosion, compresses the fuel. The shock wave, however, heats the fuel more intensively, and it makes it difficult to compress the fuel further because high temperatures invite high pressure. Adiabatic compression of the fuel is the desired result during the implosion, without the formation of a shock wave. (Author)

Shock therapy: Gris Gun's shock absorber can take the punch

Energy Technology Data Exchange (ETDEWEB)

Anon.

2000-04-01

A newly developed shock impedance tool that isolates downhole tools that measure the effects of well stimulation techniques from being damaged by the violent shaking caused by various well stimulation techniques which combine perforating and propellant technology in a single tool, is discussed. The shock exerted by a perforating gun can exceed 25,000 G forces within 100 to 300 milliseconds, may damage or even destroy the sensitive electronics housed in the various recorders that record data about fracture gradients, permeability and temperature. The shock absorber developed by Tesco Gris Gun and Computalog, incorporates the mechanics of a piston style shock absorber in combination with a progressive spring stack and energy-dampening silicone oil chambers. The end results is an EUE 'slim line' assembly that is adaptable between the gun perforating string and the electronic equipment. It is typically attached below, reducing the shock load by as much as 90 per cent. The shock absorber is now available commercially through Gris Gun's exclusive distributorship. An improved version, currently under development, will be used for wireline perforating and tubing-conveyed perforating applications. 2 figs.

Initial ISEE magnetometer results: shock observation

International Nuclear Information System (INIS)

Russell, C.T.

1979-01-01

ISEE-1 and -2 magnetic field profiles across 6 terrestrial bow shock and one interplanetary shock are examined. The inteplanetary shock illustrates the behavior of a low Mach number shock. Three examples of low or moderate β, high Mach number, quasi-perpendicular shocks are examined. These did not have upstream waves, but rather had waves growing in the field gradient. Two examples of high β shocks showed little coherence in field variation even though the two vehicles were only a few hundred kilometers apart. The authors present the joint behavior of wave, particle and field data across some of these shocks to show some of the myriad of shock features whose behavior they are now beginning to investigate. (Auth.)

Analytical solutions of hypersonic type IV shock - shock interactions

Science.gov (United States)

Frame, Michael John

An analytical model has been developed to predict the effects of a type IV shock interaction at high Mach numbers. This interaction occurs when an impinging oblique shock wave intersects the most normal portion of a detached bow shock. The flowfield which develops is complicated and contains an embedded jet of supersonic flow, which may be unsteady. The jet impinges on the blunt body surface causing very high pressure and heating loads. Understanding this type of interaction is vital to the designers of cowl lips and leading edges on air- breathing hypersonic vehicles. This analytical model represents the first known attempt at predicting the geometry of the interaction explicitly, without knowing beforehand the jet dimensions, including the length of the transmitted shock where the jet originates. The model uses a hyperbolic equation for the bow shock and by matching mass continuity, flow directions and pressure throughout the flowfield, a prediction of the interaction geometry can be derived. The model has been shown to agree well with the flowfield patterns and properties of experiments and CFD, but the prediction for where the peak pressure is located, and its value, can be significantly in error due to a lack of sophistication in the model of the jet fluid stagnation region. Therefore it is recommended that this region of the flowfield be modeled in more detail and more accurate experimental and CFD measurements be used for validation. However, the analytical model has been shown to be a fast and economic prediction tool, suitable for preliminary design, or for understanding the interactions effects, including the basic physics of the interaction, such as the jet unsteadiness. The model has been used to examine a wide parametric space of possible interactions, including different Mach number, impinging shock strength and location, and cylinder radius. It has also been used to examine the interaction on power-law shaped blunt bodies, a possible candidate for

Mechanical shock absorber

International Nuclear Information System (INIS)

Vrillon, Bernard.

1973-01-01

The mechanical shock absorber described is made of a constant thickness plate pierced with circular holes regularly distributed in such a manner that for all the directions along which the strain is applied during the shock, the same section of the substance forming the plate is achieved. The shock absorber is made in a metal standing up to extensive deformation before breaking, selected from a group comprising mild steels and austenitic stainless steels. This apparatus is used for handling pots of fast neutron reactor fuel elements [fr

Effects of Alfvénic Drift on Diffusive Shock Acceleration at Weak Cluster Shocks

Science.gov (United States)

Kang, Hyesung; Ryu, Dongsu

2018-03-01

Non-detection of γ-ray emission from galaxy clusters has challenged diffusive shock acceleration (DSA) of cosmic-ray (CR) protons at weak collisionless shocks that are expected to form in the intracluster medium. As an effort to address this problem, we here explore possible roles of Alfvén waves self-excited via resonant streaming instability during the CR acceleration at parallel shocks. The mean drift of Alfvén waves may either increase or decrease the scattering center compression ratio, depending on the postshock cross-helicity, leading to either flatter or steeper CR spectra. We first examine such effects at planar shocks, based on the transport of Alfvén waves in the small amplitude limit. For the shock parameters relevant to cluster shocks, Alfvénic drift flattens the CR spectrum slightly, resulting in a small increase of the CR acceleration efficiency, η. We then consider two additional, physically motivated cases: (1) postshock waves are isotropized via MHD and plasma processes across the shock transition, and (2) postshock waves contain only forward waves propagating along with the flow due to a possible gradient of CR pressure behind the shock. In these cases, Alfvénic drift could reduce η by as much as a factor of five for weak cluster shocks. For the canonical parameters adopted here, we suggest η ∼ 10‑4–10‑2 for shocks with sonic Mach number M s ≈ 2–3. The possible reduction of η may help ease the tension between non-detection of γ-rays from galaxy clusters and DSA predictions.

The Heliospheric Termination Shock

Science.gov (United States)

Jokipii, J. R.

2013-06-01

The heliospheric termination shock is a vast, spheroidal shock wave marking the transition from the supersonic solar wind to the slower flow in the heliosheath, in response to the pressure of the interstellar medium. It is one of the most-important boundaries in the outer heliosphere. It affects energetic particles strongly and for this reason is a significant factor in the effects of the Sun on Galactic cosmic rays. This paper summarizes the general properties and overall large-scale structure and motions of the termination shock. Observations over the past several years, both in situ and remote, have dramatically revised our understanding of the shock. The consensus now is that the shock is quite blunt, is with the front, blunt side canted at an angle to the flow direction of the local interstellar plasma relative to the Sun, and is dynamical and turbulent. Much of this new understanding has come from remote observations of energetic charged particles interacting with the shock, radio waves and radiation backscattered from interstellar neutral atoms. The observations and the implications are discussed.

A Prognostic Model for Development of Profound Shock among Children Presenting with Dengue Shock Syndrome.

Directory of Open Access Journals (Sweden)

Phung Khanh Lam

Full Text Available To identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS.We analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was "profound DSS", defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock, or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock, and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches.The analysis population included 1207 children of whom 222 (18% progressed to "profound DSS" and 433 (36% had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for "profound DSS" showed acceptable discrimination (AUC=0.69 for internal validation and calibration and is presented as a simple score-chart.Several risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas.

Bubble Dynamics and Shock Waves

CERN Document Server

2013-01-01

This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

Shocks near Jamming

Science.gov (United States)

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.

Ions upstream of the earth's bow shock: a theoretical comparison of alternative source populations

International Nuclear Information System (INIS)

Schwartz, S.J.; Thomsen, M.F.; Gosling, J.T.

1983-01-01

A theoretical framework is developed for studying trajectories of ions reflected or leaked upstream from the earth's bow shock and subject solely to the Lorentz force in a steady interplanetary magnetic field B and the V x B electric field. We include the effects of a sharp shock potential rise. Expressions are derived for the guiding center motion and gyromotion in a frame (the Hoffman-Teller frame) moving parallel to the shock surface with sufficient speed to transform the incident solar wind velocity into motion entirely along the interplanetary magnetic field: the appropriate equations are also provided to transform these motions back to the observer's frame. The utility of these expressions is illustrated by comparing the predicted upstream motions for four different source models for upstream ions: magnetic moment-conserving reflection of the solar wind ions, specular reflection of solar wind ions, magnetic moment-conserving leakage of magnetosheath ions, and leakage of magnetosheath ions parallel to the shock normal. This comparison reveals that, for identical geometries, the reflection models produce higher energies and/or gyromotion than do the leakage models. We further argue that in a single simple encounter with the shock, an ion should behave in an unmagnetized manner and hence should not conserve its magnetic moment. Conservation of magnetic moment, if it is to occur, would seem to require multiple encounters with the shock. We investigate the conditions under which such multiple encounters can occur and find that under most quasi-parallel geometries neither leaked nor reflected ions should probably conserve their magnetic moments

GYROSURFING ACCELERATION OF IONS IN FRONT OF EARTH's QUASI-PARALLEL BOW SHOCK

Energy Technology Data Exchange (ETDEWEB)

Kis, Arpad; Lemperger, Istvan; Wesztergom, Viktor [Research Centre for Astronomy and Earth Sciences, Geodetic and Geophysical Institute, Sopron (Hungary); Agapitov, Oleksiy; Krasnoselskikh, Vladimir [LPC2E/CNRS, F-45071 Orleans (France); Khotyaintsev, Yuri V. [Swedish Institute of Space Physics, SE- 751 21 Uppsala (Sweden); Dandouras, Iannis, E-mail: akis@ggki.hu, E-mail: Kis.Arpad@csfk.mta.hu [CESR, F-31028 Toulouse (France)

2013-07-01

It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-parallel bow shock resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow shock and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.

Shock-wave induced mechanoluminescence: A new technique for studying effects of shock pressure on crystals

Energy Technology Data Exchange (ETDEWEB)

Chandra, B.P.; Parganiha, S.; Sonwane, V.D. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India); Chandra, V.K. [Department of Electrical and Electronics Engineering, Chhatrapati Shivaji Institute of Technology, Shivaji Nagar, Kolihapuri, Durg 491001, Chhattisgarh (India); Jha, Piyush, E-mail: piyushjha22@rediffmail.com [Department of Applied Physics, Raipur Institute of Technology, Chhatauna, Mandir Hasuad, Raipur 492101, Chhattisgarh (India); Baghel, R.N. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India)

2016-10-15

The impact of a projectile propelled to velocities in the range of 0.5–2.5 km/s on to a target (X-cut quartz crystal) produces shock waves travelling at velocity of nearly 10 km/s in target, in which intense mechanoluminescence (ML) pulses of microsecond duration are produced, both in compression and post-compression conditions. The piezoelectric field produced due to surface charges of fractured target, causes band bending and subsequently, the free charge carriers are generated in the respective bands and the emission of ML occurs. The ML appears after a delay time t{sub th} whose value decreases with increasing value of the shock pressure. Initially, the ML intensity increases with the shock pressure because of the creation of more surfaces; however, for higher values of the shock pressure, the ML intensity tends to attain a saturation value because of the hardening of the crystals due to the creation of small crystallites in which the creation of new surfaces becomes difficult. The ratio between peak ML intensity in the uncompressed region and the maximum ML intensity in the compressed region decreases with increasing shock pressure because more defects produced at high pressure generate higher barrier for the relaxation of blocked cracks under compression. The expressions derived for characteristics of shock-induced ML are able to explain satisfactorily the experimental results. Shock-wave velocity, shock pressure, transit time, lifetime of electrons in conduction band, etc. can be determined by the shock-induced ML.As such, the shock-induced ML provides a new optical technique for the studies of materials under shock pressure.

Electric shock and elevated EMF levels due to triplen harmonics

International Nuclear Information System (INIS)

Tran, T.Q.; Conrad, L.E.; Stallman, B.K.

1996-01-01

The increasing use of single phase rectifiers for electric power conversion in residential applications increases harmonic load on utility systems. Many papers have analyzed the effect of these loads on power quality and equipment loadability. However, there are two more critical concerns for harmonic loads served phase to neutral on multi-grounded wye systems. Triplen harmonics, particularly the third, add in the neutral and have little diversity between loads. The higher neutral currents may cause significant problems. Neutral to earth voltages will increase near the substations which could increase stray voltage complaints. The additional neutral current on three phase lines will elevate EMF levels especially in the fringe areas. This paper provides fundamental understanding of triplen harmonic influence on stray voltage and EMF related to multi-grounded wye electric distribution systems

Electrical Safety and Arc Flash Protections

Energy Technology Data Exchange (ETDEWEB)

R. Camp

2008-03-04

Over the past four years, the Electrical Safety Program at PPPL has evolved in addressing changing regulatory requirements and lessons learned from accident events, particularly in regards to arc flash hazards and implementing NFPA 70E requirements. This presentation will discuss PPPL's approaches to the areas of electrical hazards evaluation, both shock and arc flash; engineered solutions for hazards mitigation such as remote racking of medium voltage breakers, operational changes for hazards avoidance, targeted personnel training and hazard appropriate personal protective equipment. Practical solutions for nominal voltage identification and zero voltage checks for lockout/tagout will also be covered. Finally, we will review the value of a comprehensive electrical drawing program, employee attitudes expressed as a personal safety work ethic, integrated safety management, and sustained management support for continuous safety improvement.

Electrical Safety and Arc Flash Protections

International Nuclear Information System (INIS)

Camp, R.

2008-01-01

Over the past four years, the Electrical Safety Program at PPPL has evolved in addressing changing regulatory requirements and lessons learned from accident events, particularly in regards to arc flash hazards and implementing NFPA 70E requirements. This presentation will discuss PPPL's approaches to the areas of electrical hazards evaluation, both shock and arc flash; engineered solutions for hazards mitigation such as remote racking of medium voltage breakers, operational changes for hazards avoidance, targeted personnel training and hazard appropriate personal protective equipment. Practical solutions for nominal voltage identification and zero voltage checks for lockout/tagout will also be covered. Finally, we will review the value of a comprehensive electrical drawing program, employee attitudes expressed as a personal safety work ethic, integrated safety management, and sustained management support for continuous safety improvement.

Prediction of massive bleeding. Shock index and modified shock index.

Science.gov (United States)

Terceros-Almanza, L J; García-Fuentes, C; Bermejo-Aznárez, S; Prieto-Del Portillo, I J; Mudarra-Reche, C; Sáez-de la Fuente, I; Chico-Fernández, M

2017-12-01

To determine the predictive value of the Shock Index and Modified Shock Index in patients with massive bleeding due to severe trauma. Retrospective cohort. Severe trauma patient's initial attention at the intensive care unit of a tertiary hospital. Patients older than 14 years that were admitted to the hospital with severe trauma (Injury Severity Score >15) form January 2014 to December 2015. We studied the sensitivity (Se), specificity (Sp), positive and negative predictive value (PV+ and PV-), positive and negative likelihood ratio (LR+ and LR-), ROC curves (Receiver Operating Characteristics) and the area under the same (AUROC) for prediction of massive hemorrhage. 287 patients were included, 76.31% (219) were male, mean age was 43,36 (±17.71) years and ISS was 26 (interquartile range [IQR]: 21-34). The overall frequency of massive bleeding was 8.71% (25). For Shock Index: AUROC was 0.89 (95% confidence intervals [CI] 0.84 to 0.94), with an optimal cutoff at 1.11, Se was 91.3% (95% CI: 73.2 to 97.58) and Sp was 79.69% (95% CI: 74.34 to 84.16). For the Modified Shock Index: AUROC was 0.90 (95% CI: 0.86 to 0.95), with an optimal cutoff at 1.46, Se was 95.65% (95% CI: 79.01 to 99.23) and Sp was 75.78% (95% CI: 70.18 to 80.62). Shock Index and Modified Shock Index are good predictors of massive bleeding and could be easily incorporated to the initial workup of patients with severe trauma. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

30th International Symposium on Shock Waves

CERN Document Server

Sadot, Oren; Igra, Ozer

2017-01-01

These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

Advanced and Exploratory Shock Sensing Mechanisms.

Energy Technology Data Exchange (ETDEWEB)

Nelsen, Nicholas H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kolb, James D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kulkarni, Akshay G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorscher, Zachary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Habing, Clayton D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mathis, Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Beller, Zachary J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

Mechanical component response to shock environments must be predictable in order to ensure reliability and safety. Whether the shock input results from accidental drops during transportation to projectile impact scenarios, the system must irreversibly transition into a safe state that is incapable of triggering the component . With this critical need in mind, the 2017 Nuclear Weapons Summer Product Realization Institute (NW SPRINT) program objective sought the design of a passive shock failsafe with emphasis on additively manufactured (AM) components. Team Advanced and Exploratory (A&E) responded to the challenge by designing and delivering multiple passive shock sensing mech anisms that activate within a prescribed mechanical shock threshold. These AM failsafe designs were tuned and validated using analytical and computational techniques including the shock response spectrum (SRS) and finite element analysis (FEA). After rapid prototyping, the devices experienced physical shock tests conducted on Sandia drop tables to experimentally verify performance. Keywords: Additive manufacturing, dynamic system, failsafe, finite element analysis, mechanical shock, NW SPRINT, shock respon se spectrum

Advanced Spectroscopic and Thermal Imaging Instrumentation for Shock Tube and Ballistic Range Facilities

Science.gov (United States)

Grinstead, Jay H.; Wilder, Michael C.; Reda, Daniel C.; Cruden, Brett A.; Bogdanoff, David W.

2010-01-01

The Electric Arc Shock Tube (EAST) facility and Hypervelocity Free Flight Aerodynamic Facility (HFFAF, an aeroballistic range) at NASA Ames support basic research in aerothermodynamic phenomena of atmospheric entry, specifically shock layer radiation spectroscopy, convective and radiative heat transfer, and transition to turbulence. Innovative optical instrumentation has been developed and implemented to meet the challenges posed from obtaining such data in these impulse facilities. Spatially and spectrally resolved measurements of absolute radiance of a travelling shock wave in EAST are acquired using multiplexed, time-gated imaging spectrographs. Nearly complete spectral coverage from the vacuum ultraviolet to the near infrared is possible in a single experiment. Time-gated thermal imaging of ballistic range models in flight enables quantitative, global measurements of surface temperature. These images can be interpreted to determine convective heat transfer rates and reveal transition to turbulence due to isolated and distributed surface roughness at hypersonic velocities. The focus of this paper is a detailed description of the optical instrumentation currently in use in the EAST and HFFAF.

The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

International Nuclear Information System (INIS)

Wu, C.C.

1988-01-01

Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

The Septic Shock 3.0 Definition and Trials: A Vasopressin and Septic Shock Trial Experience.

Science.gov (United States)

Russell, James A; Lee, Terry; Singer, Joel; Boyd, John H; Walley, Keith R

2017-06-01

The Septic Shock 3.0 definition could alter treatment comparisons in randomized controlled trials in septic shock. Our first hypothesis was that the vasopressin versus norepinephrine comparison and 28-day mortality of patients with Septic Shock 3.0 definition (lactate > 2 mmol/L) differ from vasopressin versus norepinephrine and mortality in Vasopressin and Septic Shock Trial. Our second hypothesis was that there are differences in plasma cytokine levels in Vasopressin and Septic Shock Trial for lactate less than or equal to 2 versus greater than 2 mmol/L. Retrospective analysis of randomized controlled trial. Multicenter ICUs. We compared vasopressin-to-norepinephrine group 28- and 90-day mortality in Vasopressin and Septic Shock Trial in lactate subgroups. We measured 39 cytokines to compare patients with lactate less than or equal to 2 versus greater than 2 mmol/L. Patients with septic shock with lactate greater than 2 mmol/L or less than or equal to 2 mmol/L, randomized to vasopressin or norepinephrine. Concealed vasopressin (0.03 U/min.) or norepinephrine infusions. The Septic Shock 3.0 definition would have decreased sample size by about half. The 28- and 90-day mortality rates were 10-12 % higher than the original Vasopressin and Septic Shock Trial mortality. There was a significantly (p = 0.028) lower mortality with vasopressin versus norepinephrine in lactate less than or equal to 2 mmol/L but no difference between treatment groups in lactate greater than 2 mmol/L. Nearly all cytokine levels were significantly higher in patients with lactate greater than 2 versus less than or equal to 2 mmol/L. The Septic Shock 3.0 definition decreased sample size by half and increased 28-day mortality rates by about 10%. Vasopressin lowered mortality versus norepinephrine if lactate was less than or equal to 2 mmol/L. Patients had higher plasma cytokines in lactate greater than 2 versus less than or equal to 2 mmol/L, a brisker cytokine response to infection. The Septic

Motion of shocks through interplanetary streams

International Nuclear Information System (INIS)

Burlaga, L.F.; Scudder, J.D.

1975-01-01

A model for the motion of flare-generated shocks through interplanetary streams is presented, illustrating the effects of a stream-shock interaction on the shock strength and geometry. It is a gas dynamic calculation based on Whitham's method and on an empirical approximation for the relevant characteristics of streams. The results show that the Mach number of a shock can decrease appreciably to near unity in the interaction region ahead of streams and that the interaction of a spherically symmetric shock with a spiral-shaped corotating stream can cause significant distortions of the initial shock front geometry. The geometry of the February 15--16, 1967, shock discussed by Lepping and Chao (1972) is qualitatively explained by this model

Interplanetary shocks, Plasma waves and turbulence, Kinetic waves and instabilities, STEREO spacecraft

Science.gov (United States)

Cohen, Z.; Breneman, A. W.; Cattell, C. A.; Davis, L.; Grul, P.; Kersten, K.; Wilson, L. B., III

2017-12-01

Determining the role of plasma waves in providing energy dissipation at shock waves is of long-standing interest. Interplanetary (IP) shocks serve as a large database of low Mach number shocks. We examine electric field waveforms captured by the Time Domain Sampler (TDS) on the STEREO spacecraft during the ramps of IP shocks, with emphasis on captures lasting 2.1 seconds. Previous work has used captures of shorter duration (66 and 131 ms on STEREO, and 17 ms on WIND), which allowed for observation of waves with maximum (minimum) frequencies of 125 kHz (15 Hz), 62.5 kHz (8 Hz), and 60 kHz (59 Hz), respectively. The maximum frequencies are comparable to 2-8 times the plasma frequency in the solar wind, enabling observation of Langmuir waves, ion acoustic, and some whistler-mode waves. The 2 second captures resolve lower frequencies ( few Hz), which allows us to analyze packet structure of the whistler-mode waves and some ion acoustic waves. The longer capture time also improves the resolvability of simultaneous wave modes and of waves with frequencies on the order of 10s of Hz. Langmuir waves, however, cannot be identified at this sampling rate, since the plasma frequency is usually higher than 3.9 kHz. IP shocks are identified from multiple databases (Helsinki heliospheric shock database at http://ipshocks.fi, and the STEREO level 3 shock database at ftp://stereoftp.nascom.nasa.gov/pub/ins_data/impact/level3/). Our analysis focuses on TDS captures in shock ramp regions, with ramp durations determined from magnetic field data taken at 8 Hz. Software is used to identify multiple wave modes in any given capture and classify waves as Langmuir, ion acoustic, whistler, lower hybrid, electron cyclotron drift instability, or electrostatic solitary waves. Relevant frequencies are determined from density and magnetic field data collected in situ. Preliminary results suggest that large amplitude (∼ 5 mV/m) ion acoustic waves are most prevalent in the ramp, in agreement with

Peripapillary retinal thermal coagulation following electrical injury

Directory of Open Access Journals (Sweden)

Manjari Tandon

2013-01-01

Full Text Available In this study, we have presented the case report of a 20 year old boy who suffered an electric injury shock, following which he showed peripapillary retinal opacification and increased retinal thickening that subsequently progressed to retinal atrophy. The fluorescein angiogram revealed normal retinal circulation, thus indicating thermal damage to retina without any compromise to retinal circulation.

Grain destruction in interstellar shocks

International Nuclear Information System (INIS)

Seab, C.G.; Shull, J.M.

1984-01-01

One of the principal methods for removing grains from the Interstellar Medium is to destroy them in shock waves. Previous theoretical studies of shock destruction have generally assumed only a single size and type of grain; most do not account for the effect of the grain destruction on the structure of the shock. Earlier calculations have been improved in three ways: first, by using a ''complete'' grain model including a distribution of sizes and types of grains; second, by using a self-consistent shock structure that incorporates the changing elemental depletions as the grains are destroyed; and third, by calculating the shock-processed ultraviolet extinction curves for comparison with observations. (author)

Impact of Shock Front Rippling and Self-reformation on the Electron Dynamics at Low-Mach-number Shocks

Science.gov (United States)

Yang, Zhongwei; Lu, Quanming; Liu, Ying D.; Wang, Rui

2018-04-01

Electron dynamics at low-Mach-number collisionless shocks are investigated by using two-dimensional electromagnetic particle-in-cell simulations with various shock normal angles. We found: (1) The reflected ions and incident electrons at the shock front provide an effective mechanism for the quasi-electrostatic wave generation due to the charge-separation. A fraction of incident electrons can be effectively trapped and accelerated at the leading edge of the shock foot. (2) At quasi-perpendicular shocks, the electron trapping and reflection is nonuniform due to the shock rippling along the shock surface and is more likely to take place at some locations accompanied by intense reflected ion-beams. The electron trapping process has a periodical evolution over time due to the shock front self-reformation, which is controlled by ion dynamics. Thus, this is a cross-scale coupling phenomenon. (3) At quasi-parallel shocks, reflected ions can travel far back upstream. Consequently, quasi-electrostatic waves can be excited in the shock transition and the foreshock region. The electron trajectory analysis shows these waves can trap electrons at the foot region and reflect a fraction of them far back upstream. Simulation runs in this paper indicate that the micro-turbulence at the shock foot can provide a possible scenario for producing the reflected electron beam, which is a basic condition for the type II radio burst emission at low-Mach-number interplanetary shocks driven by Coronal Mass Ejections (CMEs).

Parallel implementation of geometrical shock dynamics for two dimensional converging shock waves

Science.gov (United States)

Qiu, Shi; Liu, Kuang; Eliasson, Veronica

2016-10-01

Geometrical shock dynamics (GSD) theory is an appealing method to predict the shock motion in the sense that it is more computationally efficient than solving the traditional Euler equations, especially for converging shock waves. However, to solve and optimize large scale configurations, the main bottleneck is the computational cost. Among the existing numerical GSD schemes, there is only one that has been implemented on parallel computers, with the purpose to analyze detonation waves. To extend the computational advantage of the GSD theory to more general applications such as converging shock waves, a numerical implementation using a spatial decomposition method has been coupled with a front tracking approach on parallel computers. In addition, an efficient tridiagonal system solver for massively parallel computers has been applied to resolve the most expensive function in this implementation, resulting in an efficiency of 0.93 while using 32 HPCC cores. Moreover, symmetric boundary conditions have been developed to further reduce the computational cost, achieving a speedup of 19.26 for a 12-sided polygonal converging shock.

Cures for the shock instability: Development of a shock-stable Roe scheme

CERN Document Server

Kim, S S; Rho, O H; Kyu-Hong, S

2003-01-01

This paper deals with the development of an improved Roe scheme that is free from the shock instability and still preserves the accuracy and efficiency of the original Roe's Flux Difference Splitting (FDS). Roe's FDS is known to possess good accuracy but to suffer from the shock instability, such as the carbuncle phenomenon. As the first step towards a shock-stable scheme, Roe's FDS is compared with the HLLE scheme to identify the source of the shock instability. Through a linear perturbation analysis on the odd-even decoupling problem, damping characteristic is examined and Mach number-based functions f and g are introduced to balance damping and feeding rates, which leads to a shock-stable Roe scheme. In order to satisfy the conservation of total enthalpy, which is crucial in predicting surface heat transfer rate in high-speed steady flows, an analysis of dissipation mechanism in the energy equation is carried out to find out the error source and to make the proposed scheme preserve total enthalpy. By modif...

Shock dynamics in layered periodic media

KAUST Repository

Ketcheson, David I.

2012-01-01

Solutions of constant-coeffcient nonlinear hyperbolic PDEs generically develop shocks, even if the initial data is smooth. Solutions of hyperbolic PDEs with variable coeffcients can behave very differently. We investigate formation and stability of shock waves in a one-dimensional periodic layered medium by a computational study of time-reversibility and entropy evolution. We find that periodic layered media tend to inhibit shock formation. For small initial conditions and large impedance variation, no shock formation is detected even after times much greater than the time of shock formation in a homogeneous medium. Furthermore, weak shocks are observed to be dynamically unstable in the sense that they do not lead to significant long-term entropy decay. We propose a characteristic condition for admissibility of shocks in heterogeneous media that generalizes the classical Lax entropy condition and accurately predicts the formation or absence of shocks in these media.

Experimental Shock Transformation of Gypsum to Anhydrite: A New Low Pressure Regime Shock Indicator

Science.gov (United States)

Bell, Mary S.; Zolensky, Michael E.

2011-01-01

The shock behavior of gypsum is important in understanding the Cretaceous/Paleogene event and other terrestrial impacts that contain evaporite sediments in their targets (e.g., Mars Exploration Rover Spirit detected sulfate at Gusev crater, [1]). Most interest focuses on issues of devolatilization to quantify the production of SO2 to better understand its role in generating a temporary atmosphere and its effects on climate and biota [2,3]. Kondo and Ahrens [4] measured induced radiation emitted from single crystal gypsum shocked to 30 and 40 GPa. They observed greybody emission spectra corresponding to temperatures in the range of 3,000 to 4,000 K that are a factor of 2 to 10 times greater than calculated pressure-density energy equation of state temperatures (Hugoniot) and are high enough to melt gypsum. Chen et al. [5] reported results of shock experiments on anhydrite, gypsum, and mixtures of these phases with silica. Their observations indicated little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another report of shock experiments on calcite, anhydrite, and gypsum, Badjukov et al. [6] observed only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa but have not experimentally shocked gypsum in a step-wise manner to constrain possible incipient transformation effects. Schmitt and Hornemann [7] shock loaded anhydrite and quartz to a peak pressure of 60 GPa and report the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggested that recrystallization of anhydrite grains is the result of a solid-state transformation. They concluded that significant decomposition of anhydrite requires shock pressures higher than 60 GPa. Gupta et al. [8

Shock-induced chemistry in organic materials

Energy Technology Data Exchange (ETDEWEB)

Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory; Manner, Virginia [Los Alamos National Laboratory; Chellappa, Raja [Los Alamos National Laboratory; Yoo, Choong - Shik [WASHINGTON STATE UNIV

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.

Shocks in fragile matter

Science.gov (United States)

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.

Modelling and validation of electromechanical shock absorbers

Science.gov (United States)

Tonoli, Andrea; Amati, Nicola; Girardello Detoni, Joaquim; Galluzzi, Renato; Gasparin, Enrico

2013-08-01

Electromechanical vehicle suspension systems represent a promising substitute to conventional hydraulic solutions. However, the design of electromechanical devices that are able to supply high damping forces without exceeding geometric dimension and mass constraints is a difficult task. All these challenges meet in off-road vehicle suspension systems, where the power density of the dampers is a crucial parameter. In this context, the present paper outlines a particular shock absorber configuration where a suitable electric machine and a transmission mechanism are utilised to meet off-road vehicle requirements. A dynamic model is used to represent the device. Subsequently, experimental tests are performed on an actual prototype to verify the functionality of the damper and validate the proposed model.

Energetic ion acceleration at collisionless shocks

Science.gov (United States)

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.

Energetic ion acceleration at collisionless shocks

International Nuclear Information System (INIS)

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

Observation of a spark channel generated in water with shock wave assistance in plate-to-plate electrode configuration

Energy Technology Data Exchange (ETDEWEB)

Stelmashuk, V., E-mail: vitalij@ipp.cas.cz [Institute of Plasma Physics, Za Slovankou 3, 182 00 Prague 8 (Czech Republic)

2014-01-15

When a high voltage pulse with an amplitude of 30 kV is applied to a pair of disk electrodes at a time when a shock wave is passing between them, an electrical spark is generated. The dynamic changes in the spark morphology are studied here using a high-speed framing camera. The primary result of this work is the provision of experimental evidence of plasma instability that was observed in the channel of the electric spark.

Particle Acceleration in Two Converging Shocks

Energy Technology Data Exchange (ETDEWEB)

Wang, Xin; Wang, Na; Shan, Hao [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011 (China); Giacalone, Joe [Lunar and Planetary Laboratory, University of Arizona, Tucson AZ 85721 (United States); Yan, Yihua [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing 100012 (China); Ding, Mingde, E-mail: wangxin@xao.ac.cn [Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education, Nanjing 210093 (China)

2017-06-20

Observations by spacecraft such as ACE , STEREO , and others show that there are proton spectral “breaks” with energy E {sub br} at 1–10 MeV in some large CME-driven shocks. Generally, a single shock with the diffusive acceleration mechanism would not predict the “broken” energy spectrum. The present paper focuses on two converging shocks to identify this energy spectral feature. In this case, the converging shocks comprise one forward CME-driven shock on 2006 December 13 and another backward Earth bow shock. We simulate the detailed particle acceleration processes in the region of the converging shocks using the Monte Carlo method. As a result, we not only obtain an extended energy spectrum with an energy “tail” up to a few 10 MeV higher than that in previous single shock model, but also we find an energy spectral “break” occurring on ∼5.5 MeV. The predicted energy spectral shape is consistent with observations from multiple spacecraft. The spectral “break,” then, in this case is caused by the interaction between the CME shock and Earth’s bow shock, and otherwise would not be present if Earth were not in the path of the CME.

INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES

Directory of Open Access Journals (Sweden)

P. V. Bulat

2015-03-01

Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas

"Driverless" Shocks in the Interplanetary Medium

Science.gov (United States)

Gopalswamy, N.; Kaiser, M. L.; Lara, A.

1999-01-01

Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected {\\it in situ} by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs.

Inferior vena cava obstruction and shock

Directory of Open Access Journals (Sweden)

Megri Mohammed

2018-01-01

Full Text Available Shock is one of the most challenging life-threatening conditions with high mortality and morbidity; the outcomes are highly dependent on the early detection and management of the condition. Septic shock is the most common type of shock in the Intensive Care Unit. While not as common as other subsets of shock, obstructive shock is a significant subtype due to well defined mechanical and pathological causes, including tension pneumothorax, massive pulmonary embolism, and cardiac tamponade. We are presenting a patient with obstructive shock due to inferior vena cava obstruction secondary to extensive deep venous thrombosis. Chance of survival from obstructive shock in our patient was small; however, there was complete and immediate recovery after treatment of the obstruction on recognizing the affected vessels. This case alerts the practicing intensivist and the emergency medicine physician to consider occlusion of the great vessels other than the pulmonary artery or aorta as causes of obstructive shock.

Supersonic flow. Pt. 5 Shock waves; Fondamenti fisici dei fasci molecolari supersonici. Pt 5 Onde di Shock

Energy Technology Data Exchange (ETDEWEB)

Sanna, G.; Tomassetti, G. [L`Aquila Univ. (Italy). Dipt. di Fisica

1998-02-01

The discontinuities in the flow fields (both tangential and shocks) are considered and the equations for the quantities conserved across them are written. The post-shock flow variables are expressed by the Mach number of the incident supersonic flow and its deflection angle operated by rigid wall. Normal and oblique shocks are considered and graphs and polar diagrams are introduced. Then the reflections of a shock wave operated by a rigid wall and by the boundary between a jet and a stagnating gas are analyzed. Finally, the interactions between two distinct shock waves are considered. [Italiano] Vengono considerate le discontinuita` (tangenziali e shocks) nei campi di flusso e sono scritte le equazioni per le quantita` che si conservano attraverso di esse. Le variabili del flusso oltre lo shock sono espresse in funzione del numero di Mach del flusso supersonico incidente e dell`angolo di deflessione di questo operato da una parete rigida. I casi di shock normale, obliquo e distaccato sono considerati e sono introdotti grafici vari e rappresentazioni polari. Sono quindi considerate le riflessioni di un fronte di shock da una parete rigida e dalla frontiera tra un gas in moto ed uno stagnante. Sono infine considerate le diverse interazioni tra due shock distinti.

MHD intermediate shock discontinuities: Pt. 1

International Nuclear Information System (INIS)

Kennel, C.F.; Blandford, R.D.; Coppi, P.

1989-01-01

Recent numerical investigations have focused attention once more on the role of intermediate shocks in MHD. Four types of intermediate shock are identified using a graphical representation of the MHD Rankine-Hugoniot conditions. This same representation can be used to exhibit the close relationship of intermediate shocks to switch-on shocks and rotational discontinuities. The conditions under which intermediate discontinuities can be found are elucidated. The variations in velocity, pressure, entropy and magnetic-field jumps with upstream parameters in intermediate shocks are exhibited graphically. The evolutionary arguments traditionally advanced against intermediate shocks may fail because the equations of classical MHD are not strictly hyperbolic. (author)

Perpendicular relativistic shocks in magnetized pair plasma

Science.gov (United States)

Plotnikov, Illya; Grassi, Anna; Grech, Mickael

2018-04-01

Perpendicular relativistic (γ0 = 10) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive Shock Acceleration is observed only in weakly magnetized shocks, while a dominant contribution of Shock Drift Acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of AGN jets and in the termination shocks of Pulsar Wind Nebulae.

An Electromagnetic Gauge Technique for Measuring Shocked Particle Velocity in Electrically Conductive Samples

Science.gov (United States)

Cheng, David; Yoshinaka, Akio

2014-11-01

Electromagnetic velocity (EMV) gauges are a class of film gauges which permit the direct in-situ measurement of shocked material flow velocity. The active sensing element, typically a metallic foil, requires exposure to a known external magnetic field in order to produce motional electromotive force (emf). Due to signal distortion caused by mutual inductance between sample and EMV gauge, this technique is typically limited to shock waves in non-conductive materials. In conductive samples, motional emf generated in the EMV gauge has to be extracted from the measured signal which results from the combined effects of both motional emf and voltage changes from induced currents. An electromagnetic technique is presented which analytically models the dynamics of induced current between a copper disk moving as a rigid body with constant 1D translational velocity toward an EMV gauge, where both disk and gauge are exposed to a uniform external static magnetic field. The disk is modelled as a magnetic dipole loop where its Foucault current is evaluated from the characteristics of the fields, whereas the EMV gauge is modelled as a circuit loop immersed in the field of the magnetic dipole loop, the intensity of which is calculated as a function of space and, implicitly, time. Equations of mutual induction are derived and the current induced in the EMV gauge loop is solved, allowing discrimination of the motional emf. Numerical analysis is provided for the step response of the induced EMV gauge current with respect to the Foucault current in the moving copper sample.

Shock absorber

International Nuclear Information System (INIS)

Housman, J.J.

1978-01-01

A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

INJECTION TO RAPID DIFFUSIVE SHOCK ACCELERATION AT PERPENDICULAR SHOCKS IN PARTIALLY IONIZED PLASMAS

Energy Technology Data Exchange (ETDEWEB)

Ohira, Yutaka, E-mail: ohira@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258 (Japan)

2016-08-10

We present a three-dimensional hybrid simulation of a collisionless perpendicular shock in a partially ionized plasma for the first time. In this simulation, the shock velocity and upstream ionization fraction are v {sub sh} ≈ 1333 km s{sup −1} and f {sub i} ∼ 0.5, which are typical values for isolated young supernova remnants (SNRs) in the interstellar medium. We confirm previous two-dimensional simulation results showing that downstream hydrogen atoms leak into the upstream region and are accelerated by the pickup process in the upstream region, and large magnetic field fluctuations are generated both in the upstream and downstream regions. In addition, we find that the magnetic field fluctuations have three-dimensional structures and the leaking hydrogen atoms are injected into the diffusive shock acceleration (DSA) at the perpendicular shock after the pickup process. The observed DSA can be interpreted as shock drift acceleration with scattering. In this simulation, particles are accelerated to v ∼ 100 v {sub sh} ∼ 0.3 c within ∼100 gyroperiods. The acceleration timescale is faster than that of DSA in parallel shocks. Our simulation results suggest that SNRs can accelerate cosmic rays to 10{sup 15.5} eV (the knee) during the Sedov phase.

A complete electrical hazard classification system and its application

Energy Technology Data Exchange (ETDEWEB)

Gordon, Lloyd B [Los Alamos National Laboratory; Cartelli, Laura [Los Alamos National Laboratory

2009-01-01

The Standard for Electrical Safety in the Workplace, NFPA 70E, and relevant OSHA electrical safety standards evolved to address the hazards of 60-Hz power that are faced primarily by electricians, linemen, and others performing facility and utility work. This leaves a substantial gap in the management of electrical hazards in Research and Development (R&D) and specialized high voltage and high power equipment. Examples include lasers, accelerators, capacitor banks, electroplating systems, induction and dielectric heating systems, etc. Although all such systems are fed by 50/60 Hz alternating current (ac) power, we find substantial use of direct current (dc) electrical energy, and the use of capacitors, inductors, batteries, and radiofrequency (RF) power. The electrical hazards of these forms of electricity and their systems are different than for 50160 Hz power. Over the past 10 years there has been an effort to develop a method of classifying all of the electrical hazards found in all types of R&D and utilization equipment. Examples of the variation of these hazards from NFPA 70E include (a) high voltage can be harmless, if the available current is sufficiently low, (b) low voltage can be harmful if the available current/power is high, (c) high voltage capacitor hazards are unique and include severe reflex action, affects on the heart, and tissue damage, and (d) arc flash hazard analysis for dc and capacitor systems are not provided in existing standards. This work has led to a comprehensive electrical hazard classification system that is based on various research conducted over the past 100 years, on analysis of such systems in R&D, and on decades of experience. Initially, national electrical safety codes required the qualified worker only to know the source voltage to determine the shock hazard. Later, as arc flash hazards were understood, the fault current and clearing time were needed. These items are still insufficient to fully characterize all types of

State-in-the-art of applications of shock wave research and its future; Shogekiha no oyo gijutsu no genjo to shorai

Energy Technology Data Exchange (ETDEWEB)

Takayama, K. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science

1999-03-15

A shock wave appears when the release of accumulated energy is instantaneous. For instance, it accompanies gunpowder explosion, electric discharge, laser beam convergence, collision of high-speed objects, release of high-pressure gas, and supersonic flight. The shock wave research center of Institute of Fluid Science, Tohoku University, is engaged in researches to elucidate the basics of various shock wave phenomena and to apply the fruit to engineering, science, and medicine. In this report, some examples of recent application studies at the center are described, and the trend of shock wave researches in the future is introduced. The ultimate state of the stagnation point of a nozzle flow simulating a reentry into the atmosphere is produced by shock wave compression in a free piston shock tube which is a ground-borne experimental apparatus. Los Alamos National Laboratory, U.S., succeeded in generating metallic hydrogen of a crystalline structure by subjecting liquid hydrogen to shock wave compression, in which effort a two-stage light gas gun augmented with an accelerator was operated. A high-performance two-stage light gas gun can simulate on the ground a collision of space debris in a high vacuum. Other researches involve the elucidation of the mechanism of sonic noise. (NEDO)

Shock compression of diamond crystal

OpenAIRE

Kondo, Ken-ichi; Ahrens, Thomas J.

1983-01-01

Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the and crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and th...

Electron transport and shock ignition

Energy Technology Data Exchange (ETDEWEB)

Bell, A R; Tzoufras, M, E-mail: t.bell1@physics.ox.ac.uk [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)

2011-04-15

Inertial fusion energy (IFE) offers one possible route to commercial energy generation. In the proposed 'shock ignition' route to fusion, the target is compressed at a relatively low temperature and then ignited using high intensity laser irradiation which drives a strong converging shock into the centre of the fuel. With a series of idealized calculations we analyse the electron transport of energy into the target, which produces the pressure responsible for driving the shock. We show that transport in shock ignition lies near the boundary between ablative and heat front regimes. Moreover, simulations indicate that non-local effects are significant in the heat front regime and might lead to increased efficiency by driving the shock more effectively and reducing heat losses to the plasma corona.

Application of Underwater Shock Wave Focusing to the Development of Extracorporeal Shock Wave Lithotripsy

Science.gov (United States)

Takayama, Kazuyoshi

1993-05-01

This paper describes a summary of a research project for the development of extracorporeal shock wave lithotripsy (ESWL), which has been carried out, under close collaboration between the Shock Wave Research Center of Tohoku University and the School of Medicine, Tohoku University. The ESWL is a noninvasive clinical treatment of disintegrating human calculi and one of the most peaceful applications of shock waves. Underwater spherical shock waves were generated by explosion of microexplosives. Characteristics of the underwater shock waves and of ultrasound focusing were studied by means of holographic interferometric flow visualization and polyvinyliden-difluoride (PVDF) pressure transducers. These focused pressures, when applied to clinical treatments, could effectively and noninvasively disintegrate urinary tract stones or gallbladder stones. However, despite clincal success, tissue damage occurs during ESWL treatments, and the possible mechanism of tissue damage is briefly described.

Shock dynamics of weak imploding cylindrical and spherical shock waves with non-ideal gas effects

International Nuclear Information System (INIS)

Anand, R K

2013-01-01

The author (Anand 2012 Astrophys. Space Sci. 342 377–88) recently obtained jump relations across a shock front in non-ideal gas flow taking into consideration the equation of state for a non-ideal gas as given by Landau and Lifshitz. In this paper an analytical solution for one-dimensional adiabatic flow behind weak converging shock waves propagating in a non-ideal gas is obtained by using Whitham's (1974 Linear and Nonlinear Waves (New York: Wiley)) geometrical shock dynamics approach. The effects of an increase in (i) the propagation distance from the centre of convergence, (ii) the non-idealness parameter and (iii) the adiabatic index of the gas, on the shock velocity, pressure, density, particle velocity, adiabatic compressibility and the change in entropy across the shock front, are analyzed. The results provided a clear picture of whether and how the non-idealness parameter and the adiabatic index affect the flow field behind the imploding shock front. (paper)

Anterior wrist and medial malleolus: the optimal sites for tissue selection in electric death through hand-to-foot circuit pathway.

Science.gov (United States)

Xu, Guangtao; Su, Ruibing; Lv, Junyao; Lai, Xiaoping; Li, Xianxian; Wu, Jiayan; Hu, Bo; Xu, Long; Shen, Ruilin; Gu, Jiang; Yu, Xiaojun

2017-03-01

Specific morphological changes may be absent in some cases of electrocution shocked by the voltage of 220 V or lower. In this study, we attempted to demonstrate that the anterior wrist and medial malleolus were the optimal sites with promising and significant changes in electric death through the hand-to-foot circuit pathway. We established an electric shock rat model and observed histopathologic changes in the anterior wrist and medial malleolus. The results showed that the current intensities in the left anterior wrist and right medial malleolus were remarkably higher than those in the other sites, and the nuclei long/short (L/S) axis ratios of the arterial endotheliocyte and the skeletal muscle cell in these two areas were significantly higher than those in other parts of the body. These findings suggested that the anterior wrist and/or medial malleolus soft tissues as the narrowest parts of the limbs could be used as promising and useful sites for the assessment of electrical shock death, especially in forensic pathologic evaluation.

Electric Power Lines : Questions and Answers on Research into Health Effects.

Energy Technology Data Exchange (ETDEWEB)

United States. Bonneville Power Administration.

1994-05-01

Most people know that electric power lines, like the wiring in our homes, can cause serious electric shocks if we`re not careful. Many people also want to know whether the electric and magnetic fields (EMF) produced by power lines and other electrical devices cause health effects. The purpose of this booklet is to answer some common questions that the Bonneville Power Administration (BPA) receives about the possible effects of power lines on health. First, some basic electrical terms are defined, and electric and magnetic fields are debed. Next, answers are given to several questions about recent scientific studies. Some important information about electrical safety follows. We then describe how BPA is addressing public concerns about potential health effects of power lines. The last section tells you how to obtain more detailed information about the health and safety issues summarized in this booklet.

Shock wave interaction with turbulence: Pseudospectral simulations

International Nuclear Information System (INIS)

Buckingham, A.C.

1986-01-01

Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs

Converging shocks in elastic-plastic solids.

Science.gov (United States)

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

Experimental methods of shock wave research

CERN Document Server

Seiler, Friedrich

2016-01-01

This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.

Exploratory laser-driven shock wave studies

International Nuclear Information System (INIS)

Solem, J.C.; Veeser, L.R.

1977-11-01

We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data

Low-voltage electrical installations in medical buildings - clinical centres and hospitals

Directory of Open Access Journals (Sweden)

Simić Ninoslav

2015-01-01

Full Text Available This paper presents the observations collected during the testing of electrical installations in medical buildings. The details of the power supply, wiring systems and the implemented systems of protection against electric shocks are described. The causes of some faults during the exploitation of the facilities are presented through practical examples, and the specific problem caused by water leaking through the insulation of electrical installations is explained in detail. It is pointed out how important maintenance, monitoring and application of the latest standards in this area are, as well as adequate training of professional staff.

Inappropriate shocks in the subcutaneous ICD

DEFF Research Database (Denmark)

Olde Nordkamp, Louise R A; Brouwer, Tom F; Barr, Craig

2015-01-01

shocks have been reported. METHODS: We analyzed the incidence, predictors and management of inappropriate shocks in the EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up data from clinical centers in Europe and New Zealand. RESULTS: During a follow-up of 21 ± 13...... xyphoid to V6) reduced the risk. Reprogramming or optimization of SVT treatment after the first clinical event of inappropriate shock was successful in preventing further inappropriate shocks for cardiac oversensing and SVT events. CONCLUSIONS: Inappropriate shocks, mainly due to cardiac oversensing...

Oscillating nonlinear acoustic shock waves

DEFF Research Database (Denmark)

Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

2016-01-01

We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show that at resona......We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

Electric Power Lines : Questions and Answers on Research into Health Effects.

Energy Technology Data Exchange (ETDEWEB)

United States. Bonneville Power Administration.

1993-11-01

Most people know that electric power lines, like the wiring in our homes, can cause serious electric shocks if we`re not careful. Many people also want to know whether the electric and magnetic fields (EMF) produced by power lines and other electrical devices cause health effects. The purpose of this pamphlet is to answer some common questions that the Bonneville Power Administration (BPA) receives about the possible effects of power lines on health. (BPA is the Pacific Northwest`s Federal electric power marketing agency.) First, some basic electrical terms are defined, and electric and magnetic fields are described. Next, answers are given to several questions about recent scientific studies. We then describe how BPA is addressing public concerns raised by these studies. Some important information about electrical safety follows. The last section tells you how to obtain more detailed information about the health and safety issues summarized in this pamphlet.

Osteoblastic differentiation and stress response of human mesenchymal stem cells exposed to alternating current electric fields

Directory of Open Access Journals (Sweden)

Kaplan David L

2011-01-01

Full Text Available Abstract Background Electric fields are integral to many biological events, from maintaining cellular homeostasis to embryonic development to healing. The application of electric fields offers substantial therapeutic potential, while optimal dosing regimens and the underlying mechanisms responsible for the positive clinical impact are poorly understood. Methods The purpose of this study was to track the differentiation profile and stress response of human bone marrow derived mesenchymal stem cells (hMSCs undergoing osteogenic differentiation during exposure to a 20 mV/cm, 60 kHz electric field. Morphological and biochemical changes were imaged using endogenous two-photon excited fluorescence (TPEF and quantitatively assessed through eccentricity calculations and extraction of the redox ratio from NADH, FAD and lipofuscin contributions. Real time reverse transcriptase-polymerase chain reactions (RT-PCR were used to track osteogenic differentiation markers, namely alkaline phosphatase (ALP and collagen type 1 (col1, and stress response markers, such as heat shock protein 27 (hsp27 and heat shock protein 70 (hsp70. Comparisons of collagen deposition between the stimulated hMSCs and controls were examined through second harmonic generation (SHG imaging. Results Quantitative differences in cell morphology, as described through an eccentricity ratio, were found on days 2 and days 5 (p Conclusions Electrical stimulation is a useful tool to improve hMSC osteogenic differentiation, while heat shock proteins may reveal underlying mechanisms, and optical non-invasive imaging may be used to monitor the induced morphological and biochemical changes.

Shock waves and shock tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985

International Nuclear Information System (INIS)

Bershader, D.; Hanson, R.

1986-01-01

A detailed survey is presented of shock tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore shock tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to shock wave phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, shock wave and rarefaction wave characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in shock tubes. Shock interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of shocks in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a shock wave are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles

Initial conditions of radiative shock experiments

International Nuclear Information System (INIS)

Kuranz, C. C.; Drake, R. P.; Krauland, C. M.; Marion, D. C.; Grosskopf, M. J.; Rutter, E.; Torralva, B.; Holloway, J. P.; Bingham, D.; Goh, J.; Boehly, T. R.; Sorce, A. T.

2013-01-01

We performed experiments at the Omega Laser Facility to characterize the initial, laser-driven state of a radiative shock experiment. These experiments aimed to measure the shock breakout time from a thin, laser-irradiated Be disk. The data are then used to inform a range of valid model parameters, such as electron flux limiter and polytropic γ, used when simulating radiative shock experiments using radiation hydrodynamics codes. The characterization experiment and the radiative shock experiment use a laser irradiance of ∼7 × 10 14 W cm −2 to launch a shock in the Be disk. A velocity interferometer and a streaked optical pyrometer were used to infer the amount of time for the shock to move through the Be disk. The experimental results were compared with simulation results from the Hyades code, which can be used to model the initial conditions of a radiative shock system using the CRASH code

The role of nuclear energy meeting electricity needs in Africa

International Nuclear Information System (INIS)

Rising, R.

2017-01-01

Demand for electricity has risen dramatically regardless of economic shocks while accelerating rise in world electricity consumption. Decarbonizing electricity generation - need for low life cycle emissions: Nuclear energy is among the best and makes quick, lasting decarbonization possible. Harmonized regulatory processes: Enhance standardization, harmonize and update global codes and standards. Nuclear is regulated, financed and managed outside of normal protocols without an expansion of nuclear, many economies will fall short of their net mid-century carbon dioxide emission goal and society will fall short of the 2-degree scenario. Timely licensing of new technologies. In effective safety paradigm it good to embrace a holistic approach to society risks from electricity generation so that health and environmental benefits of all sources are maximized

Space Shuttle Program (SSP) Shock Test and Specification Experience for Reusable Flight Hardware Equipment

Science.gov (United States)

Larsen, Curtis E.

2012-01-01

As commercial companies are nearing a preliminary design review level of design maturity, several companies are identifying the process for qualifying their multi-use electrical and mechanical components for various shock environments, including pyrotechnic, mortar firing, and water impact. The experience in quantifying the environments consists primarily of recommendations from Military Standard-1540, Product Verification Requirement for Launch, Upper Stage, and Space Vehicles. Therefore, the NASA Engineering and Safety Center (NESC) formed a team of NASA shock experts to share the NASA experience with qualifying hardware for the Space Shuttle Program (SSP) and other applicable programs and projects. Several team teleconferences were held to discuss past experience and to share ideas of possible methods for qualifying components for multiple missions. This document contains the information compiled from the discussions

Collisionless Electrostatic Shock Modeling and Simulation

Science.gov (United States)

2016-10-21

equations with piston -like boundary conditions gives a solution for the shock behavior. • Assumes cold upstream ions, therefore neglecting shock...temperature ratio (>10) – Wave Train Wavelength – Shock-Front Mach Number – Reflected Ion Beam Velocity Gathering Experiment Data – Double Plasma Device...experimental shock data. • Inconsistencies in published 1969 double -plasma device data hampered validation. Future Work: Extension to Moderately

Experimental investigation of shock wave - bubble interaction

Energy Technology Data Exchange (ETDEWEB)

Alizadeh, Mohsen

2010-04-09

In this work, the dynamics of laser-generated single cavitation bubbles exposed to lithotripter shock waves has been investigated experimentally. The energy of the impinging shock wave is varied in several steps. High-speed photography and pressure field measurements simultaneously with image acquisition provide the possibility of capturing the fast bubble dynamics under the effect of the shock wave impact. The pressure measurement is performed using a fiber optic probe hydrophone (FOPH) which operates based on optical diagnostics of the shock wave propagating medium. After a short introduction in chapter 1 an overview of the previous studies in chapter 2 is presented. The reported literatures include theoretical and experimental investigations of several configurations of physical problems in the field of bubble dynamics. In chapter 3 a theoretical description of propagation of a shock wave in a liquid like water has been discussed. Different kinds of reflection of a shock wave at an interface are taken into account. Undisturbed bubble dynamics as well as interaction between a planar shock wave and an initially spherical bubble are explored theoretically. Some physical parameters which are important in this issue such as the velocity of the shock-induced liquid jet, Kelvin impulse and kinetic energy are explained. The shock waves are generated in a water filled container by a focusing piezoelectric generator. The shock wave profile has a positive part with pulse duration of ∼1 μs followed by a longer tension tail (i.e. ∼3 μs). In chapter 4 high-speed images depict the propagation of a shock wave in the water filled tank. The maximum pressure is also derived for different intensity levels of the shock wave generator. The measurement is performed in the free field (i.e. in the absence of laser-generated single bubbles). In chapter 5 the interaction between lithotripter shock waves and laserinduced single cavitation bubbles is investigated experimentally. An

Multiple shocks, coping and welfare consequences: natural disasters and health shocks in the Indian Sundarbans.

Science.gov (United States)

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

2014-01-01

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. 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. 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. 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 as well as long-run development manifestations.

Health shocks and risk aversion.

Science.gov (United States)

Decker, Simon; Schmitz, Hendrik

2016-12-01

We empirically assess whether a health shock influences individual risk aversion. We use grip strength data to obtain an objective health shock indicator. In order to account for the non-random nature of our data regression-adjusted matching is employed. Risk preferences are traditionally assumed to be constant. However, we find that a health shock increases individual risk aversion. The finding is robust to a series of sensitivity analyses and persists for at least four years after the shock. Income changes do not seem to be the driving mechanism. Copyright © 2016 Elsevier B.V. All rights reserved.

Shock in the emergency department

DEFF Research Database (Denmark)

Holler, Jon Gitz; Henriksen, Daniel Pilsgaard; Mikkelsen, Søren

2016-01-01

BACKGROUND: The knowledge of the frequency and associated mortality of shock in the emergency department (ED) is limited. The aim of this study was to describe the incidence, all-cause mortality and factors associated with death among patients suffering shock in the ED. METHODS: Population...... failures. Outcomes were annual incidence per 100,000 person-years at risk (pyar), all-cause mortality at 0-7, and 8-90 days and risk factors associated with death. RESULTS: We identified 1646 of 438,191 (0.4 %) ED patients with shock at arrival. Incidence of shock increased from 53.8 to 80.6 cases per 100...

Dynamic behaviors of a Zr-based bulk metallic glass under ramp wave and shock wave loading

Directory of Open Access Journals (Sweden)

Binqiang Luo

2015-06-01

Full Text Available Dynamic behaviors of Zr51Ti5Ni10Cu25Al9 bulk metallic glass were investigated using electric gun and magnetically driven isentropic compression device which provide shock and ramp wave loading respectively. Double-wave structure was observed under shock compression while three-wave structure was observed under ramp compression in 0 ∼ 18GPa. The HEL of Zr51Ti5Ni10Cu25Al9 is 8.97 ± 0.61GPa and IEL is 8.8 ± 0.3GPa, respectively. Strength of Zr51Ti5Ni10Cu25Al9 estimated from HEL is 5.0 ± 0.3GPa while the strength estimated from IEL is 3.6 ± 0.1GPa. Shock wave velocity versus particle velocity curve of Zr51Ti5Ni10Cu25Al9 under shock compression appears to be bilinear and a kink appears at about 18GPa. The Lagrangian sound speed versus particle velocity curve of Zr51Ti5Ni10Cu25Al9 under ramp wave compression exhibits two discontinuances and are divided to three regions: elastic, plastic-I and plastic-II. The first jump-down occurs at elastic-plastic transition and the second appears at about 17GPa. In elastic and plastic-I regions, Lagrangian sound speed increases linearly with particle velocity, respectively. Characteristic response of sound speed in plastic-I region disagree with shock result in the same pressure region(7GPa ∼ 18GPa, but is consistent with shock result at higher pressure(18-110GPa.

The source of real and nominal exchange rate fluctuations in Thailand: Real shock or nominal shock

OpenAIRE

Le Thanh, Binh

2015-01-01

This paper examines the source of exchange rate fluctuations in Thailand. We employed a structural vector auto-regression (SVAR) model with the long-run neutrality restriction of Blanchard and Quah (1989) to investigate the changes in real and nominal exchange rates from 1994 to 2015. In this paper, we assume that there are two types of shocks which related to exchange rate movements: real shocks and nominal shocks. The empirical analysis indicates that real shocks are the fundamental compon...

Remote shock sensing and notification system

Science.gov (United States)

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.

Comparing Pleasure and Pain: The Fundamental Mathematical Equivalence of Reward Gain and Shock Reduction under Variable Interval Schedules

Science.gov (United States)

Mallpress, Dave E. W.; Fawcett, Tim W.; McNamara, John M.; Houston, Alasdair I.

2012-01-01

The relationship between positive and negative reinforcement and the symmetry of Thorndike's law of effect are unresolved issues in operant psychology. Here we show that, for a given pattern of responding on variable interval (VI) schedules with the same programmed rate of food rewards (positive reinforcement VI) or electric shocks (negative…

Life shocks and homelessness.

Science.gov (United States)

Curtis, Marah A; Corman, Hope; Noonan, Kelly; Reichman, Nancy E

2013-12-01

We exploited an exogenous health shock-namely, the birth of a child with a severe health condition-to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide.

Shock formation of HCO+

International Nuclear Information System (INIS)

Elitzur, M.

1983-01-01

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. The shock enhancement of HCO + detected in the supernova remnant IC 443 by Dickenson et al. 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

ShockOmics: multiscale approach to the identification of molecular biomarkers in acute heart failure induced by shock.

Science.gov (United States)

Aletti, Federico; Conti, Costanza; Ferrario, Manuela; Ribas, Vicent; Bollen Pinto, Bernardo; Herpain, Antoine; Post, Emiel; Romay Medina, Eduardo; Barlassina, Cristina; de Oliveira, Eliandre; Pastorelli, Roberta; Tedeschi, Gabriella; Ristagno, Giuseppe; Taccone, Fabio S; Schmid-Schönbein, Geert W; Ferrer, Ricard; De Backer, Daniel; Bendjelid, Karim; Baselli, Giuseppe

2016-01-28

The ShockOmics study (ClinicalTrials.gov identifier NCT02141607) is a multicenter prospective observational trial aimed at identifying new biomarkers of acute heart failure in circulatory shock, by means of a multiscale analysis of blood samples and hemodynamic data from subjects with circulatory shock. Ninety septic shock and cardiogenic shock patients will be recruited in three intensive care units (ICU) (Hôpital Erasme, Université Libre de Bruxelles, Belgium; Hospital Universitari Mutua Terrassa, Spain; Hôpitaux Universitaires de Genève, Switzerland). Hemodynamic signals will be recorded every day for up to seven days from shock diagnosis (time T0). Clinical data and blood samples will be collected for analysis at: i) T1  5 and lactate levels ≥ 2 mmol/L. The exclusion criteria are: expected death within 24 h since ICU admission; > 4 units of red blood cells or >1 fresh frozen plasma transfused; active hematological malignancy; metastatic cancer; chronic immunodepression; pre-existing end stage renal disease requiring renal replacement therapy; recent cardiac surgery; Child-Pugh C cirrhosis; terminal illness. Enrollment will be preceded by the signature of the Informed Consent by the patient or his/her relatives and by the physician in charge. Three non-shock control groups will be included in the study: a) healthy blood donors (n = 5); b) septic patients (n = 10); c) acute myocardial infarction or patients with prolonged acute arrhythmia (n = 10). The hemodynamic data will be downloaded from the ICU monitors by means of dedicated software. The blood samples will be utilized for transcriptomics, proteomics and metabolomics ("-omics") analyses. ShockOmics will provide new insights into the pathophysiological mechanisms underlying shock as well as new biomarkers for the timely diagnosis of cardiac dysfunction in shock and quantitative indices for assisting the therapeutic management of shock patients.

Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

Science.gov (United States)

Nath, G.; Vishwakarma, J. P.

2016-11-01

Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

Particle acceleration at shocks in the inner heliosphere

Science.gov (United States)

Parker, Linda Neergaard

This dissertation describes a study of particle acceleration at shocks via the diffusive shock acceleration mechanism. Results for particle acceleration at both quasi-parallel and quasi-perpendicular shocks are presented to address the question of whether there are sufficient particles in the solar wind thermal core, modeled as either a Maxwellian or kappa- distribution, to account for the observed accelerated spectrum. Results of accelerating the theoretical upstream distribution are compared to energetic observations at 1 AU. It is shown that the particle distribution in the solar wind thermal core is sufficient to explain the accelerated particle spectrum downstream of the shock, although the shape of the downstream distribution in some cases does not follow completely the theory of diffusive shock acceleration, indicating possible additional processes at work in the shock for these cases. Results show good to excellent agreement between the theoretical and observed spectral index for one third to one half of both quasi-parallel and quasi-perpendicular shocks studied herein. Coronal mass ejections occurring during periods of high solar activity surrounding solar maximum can produce shocks in excess of 3-8 shocks per day. During solar minimum, diffusive shock acceleration at shocks can generally be understood on the basis of single independent shocks and no other shock necessarily influences the diffusive shock acceleration mechanism. In this sense, diffusive shock acceleration during solar minimum may be regarded as Markovian. By contrast, diffusive shock acceleration of particles at periods of high solar activity (e.g. solar maximum) see frequent, closely spaced shocks that include the effects of particle acceleration at preceding and following shocks. Therefore, diffusive shock acceleration of particles at solar maximum cannot be modeled on the basis of diffusive shock acceleration as a single, independent shock and the process is essentially non-Markovian. A

Melting under shock compression

International Nuclear Information System (INIS)

Bennett, B.I.

1980-10-01

A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

Various mechanisms and clinical phenotypes in electrical short circuits of high-voltage devices: report of four cases and review of the literature.

Science.gov (United States)

Tsurugi, Takuo; Matsui, Shogo; Nakajima, Hiroshi; Nishii, Nobuhiro; Honda, Toshihiro; Kaneko, Yoshiaki

2015-06-01

An electrical short circuit is a rare complication in a high-voltage implantable cardioverter-defibrillator (ICD). However, the inability of an ICD to deliver appropriate shock therapy can be life-threatening. During the last 2 years, four cases of serious complications related to an electrical short circuit have been reported in Japan. A spark due to an electrical short circuit resulted in the failure of an ICD shock to terminate ventricular tachycardia and total damage to the ICD generator in three of four cases. Two of the four patients died from an electrical short circuit between the right ventricle and superior vena cava (SVC) leads. The others had audible sounds from the ICD generator site and were diagnosed with a lead-to-can abrasion, which was manifested by the arc mark on the surface of the can. It is still difficult to predict the occurrence of an electrical short circuit in current ICD systems. To reduce the probability of an electrical short circuit, we suggest the following: (i) avoid lead stress at ICD implantation, (ii) select a single-coil lead instead of a dual-coil lead, or (iii) use a unique algorithm which automatically disconnect can or SVC lead from shock deliver circuit when excessive current was detected. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

29th International Symposium on Shock Waves

CERN Document Server

Ranjan, Devesh

2015-01-01

This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion,  Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interes...

Electrical Storm: Incidence, Prognosis and Therapy.

Science.gov (United States)

Sagone, Antonio

2015-12-01

The term "electrical storm" indicates a life-threatening clinical condition characterized by the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, in particular in patients with ICD implanted for primary or secondary prevention. Although there isn't a shared definition of electrical storm, nowadays the most accepted definition refers to three or more separate arrhythmia episodes leading to ICD therapies including antitachycardia pacing or shock occurring over a single 24 hours' time period. Clinical presentation can be dramatic and triggering mechanism are not clear at all yet, but electrical storm is associated with high mortality rates and low patients quality of life, both in the acute phase and in the long term. The first line therapy is based on antiarrhythmic drugs to suppress electrical storm, but in refractory patients, interventions such as catheter ablation or in some cases surgical cardiac sympathetic denervation might be helpful. Anyhow, earlier interventional management can lead to better outcomes than persisting with antiarrhythmic pharmacologic therapy and, when available, an early interventional approach should be preferred.

Shock compression of synthetic opal

International Nuclear Information System (INIS)

Inoue, A; Okuno, M; Okudera, H; Mashimo, T; Omurzak, E; Katayama, S; Koyano, M

2010-01-01

Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO 4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO 2 glass. However, internal silanole groups still remain even at 38.1 GPa.

Focusing of Shear Shock Waves

Science.gov (United States)

Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

2018-01-01

Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

Computations of slowly moving shocks

International Nuclear Information System (INIS)

Karni, S.; Canic, S.

1997-01-01

Computations of slowly moving shocks by shock capturing schemes may generate oscillations are generated already by first-order schemes, but become more pronounced in higher-order schemes which seem to exhibit different behaviors: (i) the first-order upwind (UW) scheme which generates strong oscillations and (ii) the Lax-Friedrichs scheme which appears not to generate any disturbances at all. A key observation is that in the UW case, the numerical viscosity in the shock family vanishes inside the slow shock layer. Simple scaling arguments show the third-order effects on the solution may no longer be neglected. We derive the third-order modified equation for the UW scheme and regard the oscillatory solution as a traveling wave solution of the parabolic modified equation for the perturbation. We then look at the governing equation for the perturbation, which points to a plausible mechanism by which postshock oscillations are generated. It contains a third-order source term that becomes significant inside the shock layer, and a nonlinear coupling term which projects the perturbation on all characteristic fields, including those not associated with the shock family. 5 refs., 8 figs

Shock compression of synthetic opal

Science.gov (United States)

Inoue, A.; Okuno, M.; Okudera, H.; Mashimo, T.; Omurzak, E.; Katayama, S.; Koyano, M.

2010-03-01

Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO2 glass. However, internal silanole groups still remain even at 38.1 GPa.

Shock compression of synthetic opal

Energy Technology Data Exchange (ETDEWEB)

Inoue, A; Okuno, M; Okudera, H [Department of Earth Sciences, Kanazawa University Kanazawa, Ishikawa, 920-1192 (Japan); Mashimo, T; Omurzak, E [Shock Wave and Condensed Matter Research Center, Kumamoto University, Kumamoto, 860-8555 (Japan); Katayama, S; Koyano, M, E-mail: okuno@kenroku.kanazawa-u.ac.j [JAIST, Nomi, Ishikawa, 923-1297 (Japan)

2010-03-01

Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO{sub 4} tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO{sub 2} glass. However, internal silanole groups still remain even at 38.1 GPa.

Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

Science.gov (United States)

Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel, and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. New simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. Furthermore, the nonlinear fluctuation amplitudes of densities, currents, and electric and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at a comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. In addition, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by tine Weibel instability scale proportionally to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields, which contribute to the electron s (positron s) transverse deflection behind the jet head. This

Do oil shocks predict economic policy uncertainty?

Science.gov (United States)

Rehman, Mobeen Ur

2018-05-01

Oil price fluctuations have influential role in global economic policies for developed as well as emerging countries. I investigate the role of international oil prices disintegrated into structural (i) oil supply shock, (ii) aggregate demand shock and (iii) oil market specific demand shocks, based on the work of Kilian (2009) using structural VAR framework on economic policies uncertainty of sampled markets. Economic policy uncertainty, due to its non-linear behavior is modeled in a regime switching framework with disintegrated structural oil shocks. Our results highlight that Indian, Spain and Japanese economic policy uncertainty responds to the global oil price shocks, however aggregate demand shocks fail to induce any change. Oil specific demand shocks are significant only for China and India in high volatility state.

Shock Wave Dynamics in Weakly Ionized Plasmas

Science.gov (United States)

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.

Shock waves in weakly compressed granular media.

Science.gov (United States)

van den Wildenberg, Siet; van Loo, Rogier; van Hecke, Martin

2013-11-22

We experimentally probe nonlinear wave propagation in weakly compressed granular media and observe a crossover from quasilinear sound waves at low impact to shock waves at high impact. We show that this crossover impact grows with the confining pressure P0, whereas the shock wave speed is independent of P0-two hallmarks of granular shocks predicted recently. The shocks exhibit surprising power law attenuation, which we model with a logarithmic law implying that shock dissipation is weak and qualitatively different from other granular dissipation mechanisms. We show that elastic and potential energy balance in the leading part of the shocks.

Shock Hugoniot measurements on Ta to 0.78 TPa

International Nuclear Information System (INIS)

Froeschner, K.E.; Lee, R.S.; Chau, H.H.; Weingart, R.C.

1983-01-01

Symmetric impact shock Hugoniot measurements have been made on Ta with an electrically exploded foil gun system. The results obtained to date for the Hugoniot of Ta cover the range 0.19 to 0.78 TPa (impact velocities from 4.0 to 9.7 km/s) and agree with data obtained by other researchers to within 2.7% rms. Recent improvements in the system include electromagnetic shielding of impactor and target, continuous measurement of impactor velocity with a Fabry-Perot interferometer and computer-aided analysis of shot film. Conservative extrapolation from current operating conditions indicate that pressures of 1.1 to 1.5 TPa could be achieved with little difficulty

A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity

International Nuclear Information System (INIS)

Ma, Wen; Hou, Yong; Zhu, Wenjun

2013-01-01

Shock compressions of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the shock front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional shock response analysis, including local stress, shear, temperature, and atom configuration. The difference between shocked Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the shock-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of shocked Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to shock front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the shocked Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the shocked Cu

Shock wave dynamics derivatives and related topics

CERN Document Server

Emanuel, George

2012-01-01

"...this monograph develops an esoteric niche within shock wave theory. …treats shock waves from an analytical approach assuming perfect gas. Emanuel has made significant contributions to the theory of shock waves and has selected a number of topics that reflect those contributions."-Shock Waves, 2013.

Strain measurements during pressurized thermal shock experiment

International Nuclear Information System (INIS)

Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

2005-01-01

For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

Chondrule destruction in nebular shocks

Energy Technology Data Exchange (ETDEWEB)

Jacquet, Emmanuel; Thompson, Christopher, E-mail: ejacquet@mnhn.fr [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St George Street, Toronto, ON M5S 3H8 (Canada)

2014-12-10

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 ε ≳ 0.1, and possibly even for solar abundances because of 'sandblasting' by finer dust. A flow with ε ≳ 10 requires much smaller shock velocities (∼2 versus 8 km s{sup –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.

Role of echocardiography in reducing shock reversal time in pediatric septic shock: a randomized controlled trial

Directory of Open Access Journals (Sweden)

Ahmed A. EL-Nawawy

Full Text Available Abstract Objective: To evaluate the role of echocardiography in reducing shock reversal time in pediatric septic shock. Methods: A prospective study conducted in the pediatric intensive care unit of a tertiary care teaching hospital from September 2013 to May 2016. Ninety septic shock patients were randomized in a 1:1 ratio for comparing the serial echocardiography-guided therapy in the study group with the standard therapy in the control group regarding clinical course, timely treatment, and outcomes. Results: Shock reversal was significantly higher in the study group (89% vs. 67%, with significantly reduced shock reversal time (3.3 vs. 4.5 days. Pediatric intensive care unit stay in the study group was significantly shorter (8 ± 3 vs. 14 ± 10 days. Mortality due to unresolved shock was significantly lower in the study group. Fluid overload was significantly lower in the study group (11% vs. 44%. In the study group, inotropes were used more frequently (89% vs. 67% and initiated earlier (12[0.5-24] vs. 24[6-72] h with lower maximum vasopressor inotrope score (120[30-325] vs. 170[80-395], revealing predominant use of milrinone (62% vs. 22%. Conclusion: Serial echocardiography provided crucial data for early recognition of septic myocardial dysfunction and hypovolemia that was not apparent on clinical assessment, allowing a timely management and resulting in shock reversal time reduction among children with septic shock.

Shock waves in luminous early-type stars

International Nuclear Information System (INIS)

Castor, J.I.

1986-01-01

Shock waves that occur in stellar atmospheres have their origin in some hydrodynamic instability of the atmosphere itself or of the stellar interior. In luminous early-type stars these two possibilities are represented by shocks due to an unstable radiatively-accelerated wind, and to shocks generated by the non-radial pulsations known to be present in many or most OB stars. This review is concerned with the structure and development of the shocks in these two cases, and especially with the mass loss that may be due specifically to the shocks. Pulsation-produced shocks are found to be very unfavorable for causing mass loss, owing to the great radiation efficiency that allows them to remain isothermal. The situation regarding radiatively-driven shocks remains unclear, awaiting detailed hydrodynamics calculations. 20 refs., 2 figs

Computer simulations of collisionless shock waves

International Nuclear Information System (INIS)

Leroy, M.M.

1984-01-01

A review of the contributions of particle computer simulations to the understanding of the physics of magnetic shock waves in collisionless plasmas is presented. The emphasis is on the relation between the computer simulation results, spacecraft observations of shocks in space, and related theories, rather than on technical aspects of the numerics. It is shown that much has been learned from the comparison of ISEE spacecraft observations of the terrestrial bow shock and particle computer simulations concerning the quasi-perpendicular, supercritical shock (ion scale structure, ion reflection mechanism and ultimate dissipation processes). Particle computer simulations have also had an appreciable prospective role in the investigation of the physics of quasi-parallel shocks, about which still little is known observationally. Moreover, these numerical techniques have helped to clarify the process of suprathermal ion rejection by the shock into the foreshock, and the subsequent evolution of the ions in the foreshock. 95 references

Shock-induced devolatilization of calcite

Science.gov (United States)

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.

Shocking matter to extreme conditions

International Nuclear Information System (INIS)

Gupta, Y.M.; Sharma, S.M.

1997-01-01

A good understanding of the thermodynamic response of matter at high compression and high energy densities is important to several areas of physics. Shock-wave experiments are uniquely suited for obtaining data at extreme conditions, and a shock-compressed matter can be viewed as a condensed system with or without dissociation or as a strongly coupled plasma. This article reviews work by Da Silva et al. in which irradiances ranging from 5x10 superscript 12 to 2x10 superscript 14 W/cm 2 were used to generate 8- to 10-ns square pulses in liquid deuterium. The authors demonstrated negligible pre-heating of the sample, steady propagation of the shock wave, and direct determination of the shock wave velocity along with particle velocity and density in the shocked state. Da Silva et al. results are compared with models and other experimental information, and the usefulness of the data in other areas is assessed. 11 refs., 1 fig

Why the Nature of Oil Shocks Matters

International Nuclear Information System (INIS)

Archanskaia, Elizaveta; Hubert, Paul; Creel, Jerome

2009-03-01

This article studies the impact of oil shocks on the macro-economy in two ways insofar unexploited in the literature. The analysis is conducted at the global level, and it explicitly accounts for the potentially changing nature of oil shocks. Based on an original world GDP series and a grouping of oil shocks according to their nature, we find that oil supply shocks negatively impact world growth, contrary to oil demand shocks, pro-cyclical in their nature. This result is robust at the national level for the US. Furthermore, endogenous monetary policy is shown to have no counter-cyclical effects in the context of an oil demand shock. (authors)

The microphysics of collisionless shock waves

DEFF Research Database (Denmark)

Marcowith, Alexandre; Bret, Antoine; Bykov, Andrei

2016-01-01

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 ga...

Laser shock wave and its applications

Science.gov (United States)

Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

2007-12-01

The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

Influence of heat shock on germination Na/sup +/ and K/sup +/ leakage and electrical conductivity of imbibed calligonum seeds

International Nuclear Information System (INIS)

Ren, J.; Tao, L.

2016-01-01

Relationships between mineral leakage and germination characteristics of five Calligonum seed in teat shock treatments were analyzed. The results suggested that heat shock stress for imbibing seeds significantly inhabited the germination and K+ leakage, and induced more seed transform death. The greater EC induced decreasing of germination of five Calligonum species, and seeds with more leakage of K+ performed greater germinability. Increasing of EC and Na+ leakage induced more seed dead. Na+ leakage and EC of germination medium always increased with temperature. K+ in seeds inhabited germination, Na+ in seeds determined the vigor of Calligonum seeds. Na+/K+ and EC both could be considered to be used for indications of seed vigor of Calligonum seeds. (author)

Shock Waves Generated by an Electrical Discharge on Composite Electrode Immersed in Water With Different Conductivities

Czech Academy of Sciences Publication Activity Database

Stelmashuk, Vitaliy; Hoffer, Petr

2012-01-01

Roč. 40, č. 7 (2012), s. 1907-1912 ISSN 0093-3813 Institutional research plan: CEZ:AV0Z20430508 Keywords : Corona * impedance matching * shock waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.868, year: 2012 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6205646&contentType=Journals+%26+ Magazines &queryText%3Dstelmashuk

Successful resuscitation of a patient with electrical storm.

Science.gov (United States)

Moulik, P K; Attar, M N; Rose, E L; Khaleeli, A A

2003-05-01

A 41 year old woman with type 2 diabetes, hypertension, and hyperlipidaemia but no known heart disease received 130 DC shocks for repeated cardiac arrests due to ventricular tachyarrhythmias over 48 hours. She was stabilised by intravenous amiodarone and had a defibrillator implanted. Serial ECGs did not change, but raised troponin I confirmed myocardial infarction as the underlying cause. Electrical storm is an uncommon and dramatic but usually treatable syndrome of recurrent ventricular arrhythmias. Frequent precipitants of electrical storm include recent worsening heart failure, hypokalaemia, hypomagnesaemia and myocardial ischaemia. Amiodarone is the antiarrhythmic agent of choice and implantable cardioverter defibrillator improves long term outcome.

Relativistic shocks and particle acceleration

International Nuclear Information System (INIS)

Heavens, A.F.

1988-01-01

In this paper, we investigate the fluid dynamics of relativistic shock waves, and use the results to calculate the spectral index of particles accelerated by the Fermi process in such shocks. We have calculated the distributions of Fermi-accelerated particles at shocks propagating into cold proton-electron plasma and also cold electron-positron plasma. We have considered two different power spectra for the scattering waves, and find, in contrast to the non-relativistic case, that the spectral index of the accelerated particles depends on the wave power spectrum. On the assumption of thermal equilibrium both upstream and downstream, we present some useful fits for the compression ratio of shocks propagating at arbitrary speeds into gas of any temperature. (author)

Shock interaction with a two-gas interface in a novel dual-driver shock tube

Science.gov (United States)

Labenski, John R.

Fluid instabilities exist at the interface between two fluids having different densities if the flow velocity and density gradient are anti-parallel or if a shock wave crosses the boundary. The former case is called the Rayleigh-Taylor (R-T) instability and the latter, the Richtmyer-Meshkov (R-M) instability. Small initial perturbations on the interface destabilize and grow into larger amplitude structures leading to turbulent mixing. Instabilities of this type are seen in inertial confinement fusion (ICF) experiments, laser produced plasmas, supernova explosions, and detonations. A novel dual-driver shock tube was used to investigate the growth rate of the R-M instability. One driver is used to create an argon-refrigerant interface, and the other at the opposite end of the driven section generates a shock to force the interface with compressible flows behind the shock. The refrigerant gas in the first driver is seeded with sub-micron oil droplets for visualization of the interface. The interface travels down the driven section past the test section for a fixed amount of time. A stronger shock of Mach 1.1 to 1.3 drives the interface back past the test section where flow diagnostics are positioned. Two schlieren systems record the density fluctuations while light scattering detectors record the density of the refrigerant as a function of position over the interface. A pair of digital cameras take stereo images of the interface, as mapped out by the tracer particles under illumination by a Q-switched ruby laser. The amount of time that the interface is allowed to travel up the driven section determines the interaction time as a control. Comparisons made between the schlieren signals, light scattering detector outputs, and the images quantify the fingered characteristics of the interface and its growth due to shock forcing. The results show that the interface has a distribution of thickness and that the interaction with a shock further broadens the interface. The

Electromagnetically driven radiative shocks and their measurements

International Nuclear Information System (INIS)

Kondo, K.; Watanabe, M.; Nakajima, M.; Kawamura, T.; Horioka, K.

2005-01-01

Experimental results on a generation of strong shocks in a compact pulse power device are reported. The characteristics of strong shocks are different from hydrodynamical shocks' because they depend on not only collisions but radiation processes. Radiative shocks are relevant to high energy density phenomena such as the explosions of supernovae. When initial pressure is lower than about 50 mtorr, an interesting structure is confirmed at the shock front, which might indicate a phenomenon proceeded by the radiative process. (author)

Entropy Generation Across Earth's Bow Shock

Science.gov (United States)

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

Risk shocks and housing markets

OpenAIRE

Dorofeenko, Viktor; Lee, Gabriel S.; Salyer, Kevin D.

2010-01-01

Abstract: This paper analyzes the role of uncertainty in a multi-sector housing model with financial frictions. We include time varying uncertainty (i.e. risk shocks) in the technology shocks that affect housing production. The analysis demonstratesthat risk shocks to the housing production sector are a quantitatively important impulse mechanism for the business cycle. Also, we demonstrate that bankruptcy costs act as an endogenous markup factor in housing prices; as a consequence, the volati...

PIV tracer behavior on propagating shock fronts

International Nuclear Information System (INIS)

Glazyrin, Fyodor N; Mursenkova, Irina V; Znamenskaya, Irina A

2016-01-01

The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48  ×  24 mm) was used. The flat shock wave with Mach numbers M  =  1.4–2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M  =  1.2–1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03  ±  0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves. (paper)

Our Favorite Film Shocks

DEFF Research Database (Denmark)

Willerslev, Rane; Suhr, Christian

2014-01-01

The modern medium of film has long been hailed for its capacity for producing shocks of an entertaining, thought-provoking, or even politically emancipative nature. But what is a shock, how and when does it occur, how long does it last, and are there particular techniques for producing cinematic...

Climate shocks and conflict

NARCIS (Netherlands)

Papaioannou, Kostadis J.

2016-01-01

This paper offers a historical micro-level analysis of the impact of climate shocks on the incidence of civil conflict in colonial Nigeria (1912-1945). Primary historical sources on court cases, prisoners and homicides are used to capture conflict. To measure climate shocks we use the deviation

Deformation response of Zr after shock-loading

International Nuclear Information System (INIS)

Song, S.G.; Gray, G.T. III, and; Lopez, M.F.

1996-01-01

The post-shock stress-strain response and microstructural evolution of Zr shock-loaded to 7 GPa were investigated. A Bauschinger effect in the room temperature reload stress-strain behavior due to shock-loading has been observed following yielding. Deformation twinning is shown to play a more important role than slip during post-shock plastic deformation and work hardening. The work hardening rate of the shock-prestrained specimens is less temperature sensitive than that of annealed Zr. The underlying microstructures responsible for the Bauschinger effect and the differences in work hardening behavior are characterized. A new type of dense dislocation arrangement occurring during the shock-wave deformation of Zr is discussed. copyright 1996 American Institute of Physics

Experimental study of micro-shock tube flow

Energy Technology Data Exchange (ETDEWEB)

Park, Jin Ouk; Kim, Gyu Wan; Rasel, Md. Alim Iftakhar [Dept. of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Kim, Heuy Dong [Fire Research Center, Korea Institute of Civil Engineering and Building Technology, Hwasung (Korea, Republic of)

2015-03-15

The flow characteristics in micro shock tube are investigated experimentally. Studies were carried out using a stainless steel micro shock tube. Shock and expansion wave was measured using 8 pressure sensors. The initial pressure ratio was varied from 4.3 to 30.5, and the diameter of tube was also changed from 3 mm to 6 mm. Diaphragm conditions were varied using two types of diaphragms. The results obtained show that the shock strength in the tube becomes stronger for an increase in the initial pressure ratio and diameter of tube. For the thinner diaphragm, the highest shock strength was found among varied diaphragm condition. Shock attenuation was highly influenced by the diameter of tube.

Radiative shocks with electron thermal conduction

International Nuclear Information System (INIS)

Borkowski, Kazimierz.

1988-01-01

The authors studies the influence of electron thermal conduction on radiative shock structure for both one- and two-temperature plasmas. The dimensionless ratio of the conductive length to the cooling length determines whether or not conduction is important, and shock jump conditions with conduction are established for a collisionless shock front. He obtains approximate solutions with the assumptions that the ionization state of the gas is constant and the cooling rate is a function of temperature alone. In the absence of magnetic fields, these solutions indicate that conduction noticeably influences normal-abundance interstellar shocks with velocities 50-100 km s -1 and dramatically affects metal-dominated shocks over a wide range of shock velocities. Magnetic fields inhibit conduction, but the conductive energy flux and the corresponding decrease in the post-shock electron temperature may still be appreciable. He calculates detailed steady-state radiative shock models in gas composed entirely of oxygen, with the purpose of explaining observations of fast-moving knots in Cas A and other oxygen-rich supernova remnants (SNRs). The O III ion, whose forbidden emission usually dominates the observed spectra, is present over a wide range of shock velocities, from 100 to 170 kms -1 . All models with conduction have extensive warm photoionization zones, which provides better agreement with observed optical (O I) line strengths. However, the temperatures in these zones could be lowered by (Si II) 34.8 μm and (Ne II) 12.8 μm cooling if Si and Ne are present in appreciable abundance relative to O. Such low temperatures would be inconsistent with the observed (O I) emission in oxygen-rich SNRs

Vorticity dynamics after the shock-turbulence interaction

Science.gov (United States)

Livescu, D.; Ryu, J.

2016-05-01

The interaction of a shock wave with quasi-vortical isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J Fluid Mech 756:R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). Using LIA to alleviate the need to resolve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number approximately 180 are used to investigate the changes in the vortical structure as a function of the shock Mach number, Ms, up to Ms=10. It is shown that, as Ms increases, the shock interaction induces a tendency towards a local axisymmetric state perpendicular to the shock front, which has a profound influence on the vortex-stretching mechanism and divergence of the Lamb vector and, ultimately, on the flow evolution away from the shock.

Shock Response of Boron Carbide

National Research Council Canada - National Science Library

Dandekar, D. P. (Dattatraya Purushottam)

2001-01-01

.... The present work was undertaken to determine tensile/spall strength of boron carbide under plane shock wave loading and to analyze all available shock compression data on boron carbide materials...

Simulation of turbulent flows containing strong shocks

International Nuclear Information System (INIS)

Fryxell, Bruce; Menon, Suresh

2008-01-01

Simulation of turbulent flows with strong shocks is a computationally challenging problem. The requirements for a method to produce accurate results for turbulence are orthogonal to those needed to treat shocks properly. In order to prevent an unphysical rate of decay of turbulent structures, it is necessary to use a method with very low numerical dissipation. Because of this, central difference schemes are widely used. However, computing strong shocks with a central difference scheme can produce unphysical post-shock oscillations that corrupt the entire flow unless additional dissipation is added. This dissipation can be difficult to localize to the area near the shock and can lead to inaccurate treatment of the turbulence. Modern high-resolution shock-capturing methods usually use upwind algorithms to provide the dissipation necessary to stabilize shocks. However, this upwind dissipation can also lead to an unphysical rate of decay of the turbulence. This paper discusses a hybrid method for simulating turbulent flows with strong shocks that couples a high-order central difference scheme with a high-resolution shock-capturing method. The shock-capturing method is used only in the vicinity of discontinuities in the flow, whereas the central difference scheme is used in the remainder of the computational domain. Results of this new method will be shown for a variety of test problems. Preliminary results for a realistic application involving detonation in gas-particle flows will also be presented.

Macroeconomic impacts of oil price shocks in Asian economies

International Nuclear Information System (INIS)

Cunado, Juncal; Jo, Soojin; Perez de Gracia, Fernando

2015-01-01

This paper analyzes the macroeconomic impact of structural oil shocks in four of the top oil-consuming Asian economies, using a VAR model. We identify three different structural oil shocks via sign restrictions: an oil supply shock, an oil demand shock driven by global economic activity and an oil-specific demand shock. The main results suggest that economic activity and prices respond very differently to oil price shocks depending on their types. In particular, an oil supply shock has a limited impact, while a demand shock driven by global economic activity has a significant positive effect in all four Asian countries examined. Our finding also includes that policy tools such as interest rates and exchange rates help mitigating the effects of supply shocks in Japan and Korea; however, they can be more actively used in response to demands shocks. - Highlights: • We analyze the effects of three structural oil price shocks on Asian economies. • Supply shocks have limited impact on the economic activity of Asian economies examined. • Demand shocks due to economic activity boosts GDP of all economies. • CPIs in India and Indonesia were only marginally affected by oil price shocks. • Monetary and exchange rate tools help mitigating supply shocks in Korea and Japan.

Shock diffraction in alumina powder

International Nuclear Information System (INIS)

Venz, G.; Killen, P.D.; Page, N.W.

1996-01-01

In order to produce complex shaped components by dynamic compaction of ceramic powders detailed knowledge of their response under shock loading conditions is required. This work attempts to provide data on release effects and shock attenuation in 1 μm and 5 μm α-alumina powders which were compacted to between 85 % and 95 % of the solid phase density by the impact of high velocity steel projectiles. As in previous work, the powder was loaded into large cylindrical dies with horizontal marker layers of a contrasting coloured powder to provide a record of powder displacement in the recovered specimens. After recovery and infiltration with a thermosetting resin the specimens were sectioned and polished to reveal the structure formed by the passage of the projectile and shock wave. Results indicate that the shock pressures generated were of the order of 0.5 to 1.4 GPa and higher, with shock velocities and sound speeds in the ranges 650 to 800 m/s and 350 to 400 m/s respectively

Overview of shock waves in medicine

Science.gov (United States)

Cleveland, Robin O.

2003-10-01

A brief overview of three applications of shock waves is presented. Shock wave lithotripsy (SWL) has been in clinical use for more than 20 years. In the United States it is used to treat more than 80% of kidney stone cases and has wide acceptance with patients because it is a noninvasive procedure. Despite SWLs enormous success there is no agreement on how shock waves comminute stones. There is also a general acceptance that shock waves lead to trauma to the soft tissue of the kidney. Yet there has been little forward progress in developing lithotripters which provide comminution with less side-effects, indeed the original machine is still considered the gold standard. The last decade has seen the advent of new shock wave devices for treating principally musculoskeletal indications, such as plantar fasciitis, tennis elbow, and bone fractures that do not heal. This is referred to as shock wave therapy (SWT). The mechanisms by which SWT works are even less well understood than SWL and the consequences of bioeffects have also not been studied in detail. Shock waves have also been shown to be effective at enhancing drug delivery into cells and assisting with gene transfection. [Work partially supported by NIH.

Heat shock proteins of higher plants

International Nuclear Information System (INIS)

Key, J.L.; Lin, C.Y.; Chen, Y.M.

1981-01-01

The pattern of protein synthesis changes rapidly and dramatically when the growth temperture of soybean seedling tissue is increased from 28 0 C (normal) to about 40 0 C (heat shock). The synthesis of normal proteins is greatly decreased and a new set of proteins, heat shock proteins, is induced. The heat shock proteins of soybean consist of 10 new bands on one-dimensional NaDodSO 4 gels; a more complex pattern is observed on two-dimensional gels. when the tissue is returned to 28 0 C after 4 hr at 40 0 C, there is progressive decline in the synthesis of heat shock proteins and reappearance of a normal pattern of synthesis by 3 or 4 hr. In vitro translation of poly(A) + RNAs isolated from tissued grown at 28 and 40 0 C shows that the heat shock proteins are translated from a ndw set of mRNAs induced at 40 0 C; furthermore, the abundant class mRNAs for many of the normal proteins persist even though they are translated weakly (or not at all) in vivo at 40 or 42.5 0 C. The heat shock response in soybean appears similar to the much-studied heat shock phenomenon in Drosophila

Impaired Fracture Healing after Hemorrhagic Shock

Directory of Open Access Journals (Sweden)

Philipp Lichte

2015-01-01

Full Text Available Impaired fracture healing can occur in severely injured patients with hemorrhagic shock due to decreased soft tissue perfusion after trauma. We investigated the effects of fracture healing in a standardized pressure controlled hemorrhagic shock model in mice, to test the hypothesis that bleeding is relevant in the bone healing response. Male C57/BL6 mice were subjected to a closed femoral shaft fracture stabilized by intramedullary nailing. One group was additionally subjected to pressure controlled hemorrhagic shock (HS, mean arterial pressure (MAP of 35 mmHg for 90 minutes. Serum cytokines (IL-6, KC, MCP-1, and TNF-α were analyzed 6 hours after shock. Fracture healing was assessed 21 days after fracture. Hemorrhagic shock is associated with a significant increase in serum inflammatory cytokines in the early phase. Histologic analysis demonstrated a significantly decreased number of osteoclasts, a decrease in bone quality, and more cartilage islands after hemorrhagic shock. μCT analysis showed a trend towards decreased bone tissue mineral density in the HS group. Mechanical testing revealed no difference in tensile failure. Our results suggest a delay in fracture healing after hemorrhagic shock. This may be due to significantly diminished osteoclast recruitment. The exact mechanisms should be studied further, particularly during earlier stages of fracture healing.

Collisionless Weibel shocks: Full formation mechanism and timing

Energy Technology Data Exchange (ETDEWEB)

Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain); Stockem, A. [GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisbon (Portugal); Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Narayan, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51 Cambridge, Massachusetts 02138 (United States); Silva, L. O. [GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisbon (Portugal)

2014-07-15

Collisionless shocks in plasmas play an important role in space physics (Earth's bow shock) and astrophysics (supernova remnants, relativistic jets, gamma-ray bursts, high energy cosmic rays). While the formation of a fluid shock through the steepening of a large amplitude sound wave has been understood for long, there is currently no detailed picture of the mechanism responsible for the formation of a collisionless shock. We unravel the physical mechanism at work and show that an electromagnetic Weibel shock always forms when two relativistic collisionless, initially unmagnetized, plasma shells encounter. The predicted shock formation time is in good agreement with 2D and 3D particle-in-cell simulations of counterstreaming pair plasmas. By predicting the shock formation time, experimental setups aiming at producing such shocks can be optimised to favourable conditions.

Cosmic ray acceleration by large scale galactic shocks

International Nuclear Information System (INIS)

Cesarsky, C.J.; Lagage, P.O.

1987-01-01

The mechanism of diffusive shock acceleration may account for the existence of galactic cosmic rays detailed application to stellar wind shocks and especially to supernova shocks have been developed. Existing models can usually deal with the energetics or the spectral slope, but the observed energy range of cosmic rays is not explained. Therefore it seems worthwhile to examine the effect that large scale, long-lived galactic shocks may have on galactic cosmic rays, in the frame of the diffusive shock acceleration mechanism. Large scale fast shocks can only be expected to exist in the galactic halo. We consider three situations where they may arise: expansion of a supernova shock in the halo, galactic wind, galactic infall; and discuss the possible existence of these shocks and their role in accelerating cosmic rays

Performance of electrical contact pins near a nuclear explosion

International Nuclear Information System (INIS)

Ragan, C.E.; Silbert, M.G.; Ellis, A.N.; Robinson, E.E.; Daddario, M.J.

1977-09-01

The pressures attainable in equation-of-state studies using nuclear-explosion-driven shock waves greatly exceed those that can be reached in normal laboratory conditions. However, the diagnostic instrumentation must survive in the high-radiation environment present near such an explosion. Therefore, a set of experiments were fielded on the Redmud event to test the feasibility of using electrical contact pins in this environment. In these experiments a 60-cm-high shield of boron-lead was placed on the rack lid approximately 1 m from the device. A sample consisting of slabs of molybdenum and 238 U was placed on top of the shield, and twelve electrical contact pins were embedded to five different depths in the materials. Five different multiplexing-charging circuits were used for the pins, and a piezoelectric quartz gauge was placed on top of the uranium to obtain an estimate of the fission-energy deposition. All of the charged pins survived the radiation and produced signals indicating shock arrival. The uncertainty in determining the pin-closure time was approximately 3 ns. The signal from the quartz gauge corresponded to a pressure that was consistent with the calculated neutron fluence

Observational test of shock drift and Fermi acceleration on a seed particle population upstream of earth's bow shock

Science.gov (United States)

Anagnostopoulos, G. C.; Sarris, E. T.; Krimigis, S. M.

1988-01-01

The efficiency of proposed shock acceleration mechanisms as they operate at the bow shock in the presence of a seed energetic particle population was examined using data from simultaneous observations of energetic solar-origin protons, carried out by the IMP 7 and 8 spacecraft in the vicinity of the quasi-parallel (dawn) and quasi-perpendicular (dusk) regions of the earth's bow shock, respectively. The results of observations (which include acceleration effects in the intensities of the energetic protons with energies as high as 4 MeV observed at the vicinity of the dusk bow shock, but no evidence for any particle acceleration at the energy equal to or above 50 keV at the dawn side of the bow shock) indicate that the acceleration of a seed particle population occurs only at the quasi-perpendicular bow shock through shock drift acceleration and that the major source of observed upstream ion populations is the leakage of magnetospheric ions of energies not less than 50 keV, rather than in situ acceleration.

Do structural oil-market shocks affect stock prices?

International Nuclear Information System (INIS)

Apergis, Nicholas; Miller, Stephen M.

2009-01-01

This paper investigates how explicit structural shocks that characterize the endogenous character of oil price changes affect stock-market returns in a sample of eight countries - Australia, Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States. For each country, the analysis proceeds in two steps. First, modifying the procedure of Kilian [Not All Oil Price Shocks are Alike: Disentangling Demand and Supply Shocks in the Crude Oil Market. American Economic Review.], we employ a vector error-correction or vector autoregressive model to decompose oil-price changes into three components: oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks. The last component relates to specific idiosyncratic features of the oil market, such as changes in the precautionary demand concerning the uncertainty about the availability of future oil supplies. Second, recovering the oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks from the first analysis, we then employ a vector autoregressive model to determine the effects of these structural shocks on the stock market returns in our sample of eight countries. We find that international stock market returns do not respond in a large way to oil market shocks. That is, the significant effects that exist prove small in magnitude. (author)

THE ROLE OF PICKUP IONS ON THE STRUCTURE OF THE VENUSIAN BOW SHOCK AND ITS IMPLICATIONS FOR THE TERMINATION SHOCK

International Nuclear Information System (INIS)

Lu Quanming; Shan Lican; Zhang Tielong; Wu Mingyu; Wang Shui; Zank, Gary P.; Yang Zhongwei; Du Aimin

2013-01-01

The recent crossing of the termination shock by Voyager 2 has demonstrated the important role of pickup ions (PUIs) in the physics of collisionless shocks. The Venus Express (VEX) spacecraft orbits Venus in a 24 hr elliptical orbit that crosses the bow shock twice a day. VEX provides a unique opportunity to investigate the role of PUIs on the structure of collisionless shocks more generally. Using VEX observations, we find that the strength of the Venusian bow shock is weaker when solar activity is strong. We demonstrate that this surprising anti-correlation is due to PUIs mediating the Venusian bow shock

Shock-hydrodynamics experiments on the Nova laser

International Nuclear Information System (INIS)

Miller, P.; Peyser, T.; Stry, P.; Budil, K.; Wojtowicz, D.; Burke, E.

1995-08-01

We have conducted shock-induced hydrodynamics experiments using the Nova laser at Lawrence Livermore National Laboratory. The laser provides a high-enthalpy source by depositing its energy (about 22 kJ) in a small gold cavity called a Hohlraum. The Hohlraum serves as a driver section, launching very strong (M ∼ 20) shocks into millimeter-scale cylindrical ''shock tubes.'' The flow is imaged radiographically by an electronic framing camera, using a laser-generated x-ray source. Several topics have been addressed with this configuration, including shock-induced mixing at density interfaces (seeded with a variety of perturbations); the development of high-speed, shaped-charge-like jets; the effects of geometry on the planarity of the generated shocks; and shock-shock interactions which develop in the flows. This paper describes the general configuration of our experiments, presents an overview of the high-speed jet work, discusses some of our findings, and compares our results with computer simulations

Technology shocks matter

OpenAIRE

Jonas D. M. Fisher

2002-01-01

This paper uses the neoclassical growth model to identify the effects of technological change on the US business cycle. In the model there are two sources of technological change: neutral, which effects the production of all goods homogeneously, and investment-specific. Investment-specific shocks are the unique source of the secular trend in the real price of investment goods, while shocks to both kinds of technology are the only factors which affect labor productivity in the long run. Consis...

Numerical simulation of nanosecond-pulse electrical discharges

Science.gov (United States)

Poggie, J.; Adamovich, I.; Bisek, N.; Nishihara, M.

2013-02-01

Recent experiments with a nanosecond-pulse, dielectric barrier discharge at the stagnation point of a Mach 5 cylinder flow have demonstrated the formation of weak shock waves near the electrode edge, which propagate upstream and perturb the bow shock. This is a promising means of flow control, and understanding the detailed physics of the conversion of electrical energy into gas motion will aid in the design of efficient actuators based on the concept. In this work, a simplified configuration with planar symmetry was chosen as a vehicle to develop a physics-based model of nanosecond-pulse discharges, including realistic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced plasma kinetic model (23 species and 50 processes) was developed to capture the dominant species and reactions for energy storage and thermalization in the discharge. The kinetic model included electronically and vibrationally excited species, and several species of ions and ground state neutrals. The governing equations included the Poisson equation for the electric potential, diffusion equations for each neutral species, conservation equations for each charged species, and mass-averaged conservation equations for the bulk gas flow. The results of calculations with this model highlighted the path of energy transfer in the discharge. At breakdown, the input electrical energy was transformed over a time scale on the order of 1 ns into chemical energy of ions, dissociation products, and vibrationally and electronically excited particles. About 30% of this energy was subsequently thermalized over a time scale of 10 µs. Since the thermalization time scale was faster than the acoustic time scale, the heat release led to the formation of weak shock waves originating near the sheath edge, consistent with experimental observations. The computed translational temperature rise (40 K) and nitrogen vibrational temperature rise (370 K) were of the same order of magnitude as

Thermal shock investigation of silicon nitride

International Nuclear Information System (INIS)

Ziegler, G.; Leucht, R.

1977-01-01

In this work, the thermal shock properties of commercial reaction-bonded Si 3 N 4 quality material (RBSN), of commercial hot-pressed Si 3 N 4 (HPSN) and of different laboratory grades of hot-pressed Si 3 N 4 were examined. The thermal shock properties of RBSN quality material differ according to the structure considerably: The critical temperature difference for sample crossections of 5 x 5 or 6 x 6 mm after quenching in oil lies between 730 0 C and over 1400 0 C. The best thermal shock properties are shown by high density RBSN quality material having very fine pores and high initial strength. The results indicate that for RBSN large pores and density inhomogenities are responsible for bad thermal shock properties. Resistance to fast temperature change is higher for hot-pressed Si 3 N 4 than for RBSN quality material. In HPSN, the thermal shock results show dependence on structure. High MgO content and the associated coarse rod-shaped configuration of the β phase and structural inhomogenities affect the thermal shock properties in an adverse way. (orig.) [de

Rate shock crisis faces completed nukes

International Nuclear Information System (INIS)

Utroska, D.

1982-01-01

Political reluctance on the part of regulators to grant utilities a full rate base for large generating plants is a new crisis facing utilities with newly completed nuclear plants. Zero- or partial-rate treatment for large new plants will increase the financial strains of electric companies if they cannot recover their investment. Such rate decisions will affect the commitment to uncompleted and planned nuclear plants as the economic advantage is removed. Economists warn that consumer resistance to large rate increases to cover construction periods could lead to an overhaul of regulatory practices. Alternatives to sudden rate shocks could be moderated with phased-in increases or rate trending. Analysts disagree on whether consumer opposition is the beginning of a national movement or a regional response, but if other states follow Alabama's example of turning rate decisions over to the courts, it may confirm their assessment that the trending approach is unworkable

Modeling of Particle Acceleration at Multiple Shocks Via Diffusive Shock Acceleration: Preliminary Results

Science.gov (United States)

Parker, L. N.; Zank, G. P.

2013-12-01

Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al., 1999) in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box (Melrose and Pope, 1993; Zank et al., 2000). We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010) and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

Shock wave of vapor-liquid two-phase flow

Institute of Scientific and Technical Information of China (English)

Liangju ZHAO; Fei WANG; Hong GAO; Jingwen TANG; Yuexiang YUAN

2008-01-01

The shock wave of vapor-liquid two-phase flow in a pressure-gain steam injector is studied by build-ing a mathematic model and making calculations. The results show that after the shock, the vapor is nearly com-pletely condensed. The upstream Mach number and the volume ratio of vapor have a great effect on the shock. The pressure and Mach number of two-phase shock con-form to the shock of ideal gas. The analysis of available energy shows that the shock is an irreversible process with entropy increase.

The ''injection problem'' for quasiparallel shocks

International Nuclear Information System (INIS)

Zank, G. P.; Rice, W. K. M.; le Roux, J. A.; Cairns, I. H.; Webb, G. M.

2001-01-01

For a particle to be accelerated diffusively at a shock by the first-order Fermi acceleration mechanism, the particle must be sufficiently energetic that it can scatter across all the micro- and macrostructure of the shock, experiencing compression between the converging upstream and downstream states. This is the well-known ''injection problem.'' Here the interaction of ions with the ramp of a quasiparallel shock is investigated. Some ions incident on the shock experience specular reflection, caused either by the cross-shock electrostatic potential or by mirroring as the magnetic field is bent and compressed through the ramp. Scattering of reflected ions by self-generated and pre-existing turbulence in the region upstream of the shock then acts to trap backstreaming ions and return them to the ramp, where some experience further reflections. Such repeated reflections and scattering energize a subpopulation of ions up to energies sufficiently large that they can be diffusively shock accelerated. Two ion distributions are considered: pickup ions which are assumed to be described by a shell distribution, are thermal solar wind ions which may be described by a kappa distribution. Injection efficiencies are found analytically to be very high for pickup ions and much lower for thermal solar wind ions, suggesting that this injection mechanism, stochastic reflected ion or SRI acceleration, is a natural precursor for the acceleration of the anomalous cosmic ray component at a quasiparallel shock. While significantly less efficient, SRI acceleration is also viable for thermal solar wind ions described by a kappa distribution

Discrimination of Thermal versus Mechanical Effects of Shock on Rock Magnetic Properties of Spherically Shocked up to 10-160 GPa Basalt and Diabase

Science.gov (United States)