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Sample records for ballistic pressure wave

  1. The Ballistic Pressure Wave Theory of Handgun Bullet Incapacitation

    CERN Document Server

    Courtney, Michael

    2008-01-01

    This paper presents a summary of seven distinct chains of evidence, which, taken together, provide compelling support for the theory that a ballistic pressure wave radiating outward from the penetrating projectile can contribute to wounding and incapacitating effects of handgun bullets. These chains of evidence include the fluid percussion model of traumatic brain injury, observations of remote ballistic pressure wave injury in animal models, observations of rapid incapacitation highly correlated with pressure magnitude in animal models, epidemiological data from human shootings showing that the probability of incapacitation increases with peak pressure magnitude, case studies in humans showing remote pressure wave damage in the brain and spinal cord, and observations of blast waves causing remote brain injury.

  2. Links between traumatic brain injury and ballistic pressure waves originating in the thoracic cavity and extremities

    CERN Document Server

    Courtney, Amy

    2007-01-01

    Identifying patients at risk of traumatic brain injury (TBI) is important because research suggests prophylactic treatments to reduce risk of long-term sequelae. Blast pressure waves can cause TBI without penetrating wounds or blunt force trauma. Similarly, bullet impacts distant from the brain can produce pressure waves sufficient to cause mild to moderate TBI. The fluid percussion model of TBI shows that pressure impulses of 15-30 psi cause mild to moderate TBI in laboratory animals. In pigs and dogs, bullet impacts to the thigh produce pressure waves in the brain of 18-45 psi and measurable injury to neurons and neuroglia. Analyses of research in goats and epidemiological data from shooting events involving humans show high correlations (r > 0.9) between rapid incapacitation and pressure wave magnitude in the thoracic cavity. A case study has documented epilepsy resulting from a pressure wave without the bullet directly hitting the brain. Taken together, these results support the hypothesis that bullet imp...

  3. Field mapping of ballistic pressure pulse sources

    Directory of Open Access Journals (Sweden)

    Rad Abtin Jamshidi

    2015-09-01

    Full Text Available Ballistic pressure pulse sources are used since late 1990s for the extracorporeal treatment of chronic Enthesitis. Newly indications are found in trigger-point-therapy for the treatment of musculoskeletal disorders. In both applications excellent results without relevant side effects were found in clinical trials. The technical principle of pressure pulse source is based on the same techniques used in air guns. A projectile is accelerated by pressurized air and hits the applicator with high kinetic energy. By this a compression wave travels through the material and induces a fast (4..5μs, almost singular pressure pulse of 2..10 MPa, which is followed by an equally short rarefaction phase of about the same amplitude. It is assumed that the pressure pulse accounts for the biomedical effects of the device. The slower inertial motion of the waveguide is damped by elastic stoppers, but still can be measured several micro seconds after the initial pressure pulse. In order to characterize the pressure pulse devices, field mapping is performed on several radial pressure pulse sources using the fiber optic hydrophone and a polyvinylidenfluorid (PVDF piezoelectric hydrophone. It could be shown that the current standard (IEC 61846 is not appropriate for characterization of ballistic pressure pulse sources.

  4. Wave propagation in ballistic gelatine.

    Science.gov (United States)

    Naarayan, Srinivasan S; Subhash, Ghatu

    2017-01-23

    Wave propagation characteristics in long cylindrical specimens of ballistic gelatine have been investigated using a high speed digital camera and hyper elastic constitutive models. The induced transient deformation is modelled with strain rate dependent Mooney-Rivlin parameters which are determined by modelling the stress-strain response of gelatine at a range of strain rates. The varying velocity of wave propagation through the gelatine cylinder is derived as a function of prestress or stretch in the gelatine specimen. A finite element analysis is conducted using the above constitutive model by suitably defining the impulse imparted by the polymer bar into the gelatine specimen. The model results are found to capture the experimentally observed wave propagation characteristics in gelatine effectively.

  5. Ballistic quench-induced correlation waves in ultracold gases

    CERN Document Server

    Corson, John P

    2016-01-01

    We investigate the wave packet dynamics of a pair of particles that undergoes a rapid change of scattering length. The short-range interactions are modeled in the zero-range limit, where the quench is accomplished by switching the boundary condition of the wave function at vanishing particle separation. This generates a correlation wave that propagates rapidly to nonzero particle separations. We have derived universal, analytic results for this process that lead to a simple phase-space picture of the quench-induced scattering. Intuitively, the strength of the correlation wave relates to the initial contact of the system. We find that, in one spatial dimension, the $k^{-4}$ tail of the momentum distribution contains a ballistic contribution that does not originate from short-range pair correlations, and a similar conclusion can hold in other dimensionalities depending on the quench protocol. We examine the resultant quench-induced transport in an optical lattice in 1D, and a semiclassical treatment is found to...

  6. A Thoracic Mechanism of Mild Traumatic Brain Injury Due to Blast Pressure Waves

    CERN Document Server

    Courtney, Amy; 10.1016/j.mehy.2008.08.015

    2008-01-01

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

  7. Observation of Strong Reflection of Electron Waves Exiting a Ballistic Channel at Low Energy

    Science.gov (United States)

    Vaz, Canute I.; Liu, Changze; Campbell, Jason P.; Ryan, Jason T.; Southwick, Richard G.; Gundlach, David; Oates, Anthony S.; Huang, Ru; Cheung, Kin. P.

    2016-01-01

    Wave scattering by a potential step is a ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the potential step is encountered upon exiting the device. Experiments so far seem to support this even if it is not clear why. Here we report clear evidence of coherent reflection when electron wave exits the channel of a nanoscale transistor and when the electron energy is low. The observed behavior is well described by a simple rectangular potential barrier model which the Schrodinger's equation can be solved exactly. We can explain why reflection is not observed in most situations but cannot be ignored in some important situations. Our experiment also represents a direct measurement of electron injection velocity - a critical quantity in nanoscale transistors that is widely considered not measurable. PMID:27882264

  8. Temporal cavity and pressure distribution in a brain simulant following ballistic penetration.

    Science.gov (United States)

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A; Gennarelli, Thomas A

    2005-11-01

    To study ballistic brain injury biomechanics, two common civilian full metal jacket handgun projectiles (25-caliber and 9-mm) were discharged into a transparent brain simulant (Sylgard gel). Five pressure transducers were placed at the entry (two), exit (two) and center (one) of the simulant. High-speed digital video photography (20,000 frames/second) was used to capture the temporal cavity pulsation. Pressure histories and high-speed video images were synchronized with a common trigger. Pressure data were sampled at 308 kHz. The 25-caliber projectile had an entry velocity of 238 m/s and exit velocity of 170 m/s. The 9-mm projectile had an entry velocity of 379 m/s and exit velocity of 259 m/s. Kinetic energies lost during penetration were 45.2 J for the 25-caliber projectile and 283.7 J for the 9-mm. Size of temporary cavities and pressures were dependent on projectile size and velocity. The 9-mm projectile created temporary cavities 1.5 times larger in size and lasted 1.5 times longer than the 25-caliber projectile. The 9-mm projectile had pressures three times higher than the 25-caliber projectile. Pressure differences between the center location and surrounding regions were approximately 1.4 times higher and lasted about 1.6 times longer in the 9- mm projectile than the 25-caliber projectile. Collapsing of the temporary cavity drew the brain simulant toward the center of the temporary cavity and created negative pressures of approximately -0.5 atmospheric pressure in the surrounding region. Pressures reached approximately +2 atmospheric pressure when temporary cavities collapsed. These quantified data may assist in understanding injury biomechanics and management of penetration brain trauma.

  9. Wave effects on a pressure sensor

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; DeSa, E.J.; Desa, E.; McKeown, J.; Peshwe, V.B.

    Wave flume experiments indicated that for waves propagating on quiescent waters the sensor's performance improved (i.e. the difference Delta P between the average hydrostatic and measured pressures was small and positive) when the inlet...

  10. The effect of high-pressure devitrification and densification on ballistic-penetration resistance of fused silica

    Science.gov (United States)

    Avuthu, Vasudeva Reddy

    Despite the clear benefits offered by more advanced transparent materials, (e.g. transparent ceramics offer a very attractive combination of high stiffness and high hardness levels, highly-ductile transparent polymers provide superior fragment-containing capabilities, etc.), ballistic ceramic-glass like fused-silica remains an important constituent material in a majority of transparent impact-resistant structures (e.g. windshields and windows of military vehicles, portholes in ships, ground vehicles and spacecraft) used today. Among the main reasons for the wide-scale use of glass, the following three are most frequently cited: (i) glass-structure fabrication technologies enable the production of curved, large surface-area, transparent structures with thickness approaching several inches; (ii) relatively low material and manufacturing costs; and (iii) compositional modifications, chemical strengthening, and controlled crystallization have been demonstrated to be capable of significantly improving the ballistic properties of glass. In the present work, the potential of high-pressure devitrification and densification of fused-silica as a ballistic-resistance-enhancement mechanism is investigated computationally. In the first part of the present work, all-atom molecular-level computations are carried out to infer the dynamic response and material microstructure/topology changes of fused silica subjected to ballistic impact by a nanometer-sized hard projectile. The analysis was focused on the investigation of specific aspects of the dynamic response and of the microstructural changes such as the deformation of highly sheared and densified regions, and the conversion of amorphous fused silica to SiO2 crystalline allotropic modifications (in particular, alpha-quartz and stishovite). The microstructural changes in question were determined by carrying out a post-processing atom-coordination procedure. This procedure suggested the formation of high-density stishovite (and

  11. Optoheterodyne Doppler measurements of the ballistic expansion of the products of the shock wave-induced surface destruction: Experiment and theory

    Science.gov (United States)

    Andriyash, A. V.; Astashkin, M. V.; Baranov, V. K.; Golubinskii, A. G.; Irinichev, D. A.; Kondrat'ev, A. N.; Kuratov, S. E.; Mazanov, V. A.; Rogozkin, D. B.; Stepushkin, S. N.; Khatunkin, V. Yu.

    2016-06-01

    The results of optoheterodyne Doppler measurements of the ballistic expansion of the products of surface destruction under shock-wave loading are presented. The possibility of determining the physical characteristics of a rapidly flying dust cloud, including the microparticle velocities, the microparticle sizes, and the areal density of the dust cloud, is shown. A compact stand for performing experiments on shock-wave loading of metallic samples is described. Shock-wave loading is performed by a 100-µm-thick tantalum flyer plate accelerated to a velocity of 2.8 km/s. As the samples, lead plates having various thicknesses and the same surface roughness are used. At a shock-wave pressure of 31.5 GPa, the destruction products are solid microparticles about 50 µm in size. At a pressure of 42 and 88 GPa, a liquid-drop dust cloud with a particle size of 10-15 µm is formed. To interpret the spectral data on the optoheterodyne Doppler measurements of the expansion of the surface destruction products (spalled fragments, dust microparticles), a transport equation for the function of mutual coherence of a multiply scattered field is used. The Doppler spectra of a backscattered signal are calculated with the model developed for the dust cloud that appears when a shock wave reaches the sample surface at the parameters that are typical of an experimental situation. Qualitative changes are found in the spectra, depending on the optical thickness of the dust cloud. The obtained theoretical results are in agreement with the experimental data.

  12. Influence of air pressure on mechanical effect of laser plasma shock wave

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu-Zhu; Wang Guang-An; Zhu Jin-Rong; Shen Zhong-Hua; Ni Xiao-Wu; Lu Jian

    2007-01-01

    The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd:YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06μm wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from 2.8 × 103 to 1.01×105pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure.

  13. Pressure diffusion waves in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitry; Korneev, Valeri; Goloshubin, Gennady

    2003-04-08

    Pressure diffusion wave in porous rocks are under consideration. The pressure diffusion mechanism can provide an explanation of the high attenuation of low-frequency signals in fluid-saturated rocks. Both single and dual porosity models are considered. In either case, the attenuation coefficient is a function of the frequency.

  14. Pressure waves in a supersaturated bubbly magma

    Science.gov (United States)

    Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

    2011-01-01

    We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

  15. Modulated pressure waves in large elastic tubes.

    Science.gov (United States)

    Mefire Yone, G R; Tabi, C B; Mohamadou, A; Ekobena Fouda, H P; Kofané, T C

    2013-09-01

    Modulational instability is the direct way for the emergence of wave patterns and localized structures in nonlinear systems. We show in this work that it can be explored in the framework of blood flow models. The whole modified Navier-Stokes equations are reduced to a difference-differential amplitude equation. The modulational instability criterion is therefore derived from the latter, and unstable patterns occurrence is discussed on the basis of the nonlinear parameter model of the vessel. It is found that the critical amplitude is an increasing function of α, whereas the region of instability expands. The subsequent modulated pressure waves are obtained through numerical simulations, in agreement with our analytical expectations. Different classes of modulated pressure waves are obtained, and their close relationship with Mayer waves is discussed.

  16. Relative incapacitation contributions of pressure wave and wound channel in the Marshall and Sanow data set

    CERN Document Server

    Courtney, M; Courtney, Amy; Courtney, Michael

    2007-01-01

    The Marshall and Sanow data set is the largest and most comprehensive data set available quantifying handgun bullet effectiveness in humans. This article presents an empirical model for relative incapacitation probability in humans hit in the thoracic cavity by handgun bullets. The model is constructed by employing the hypothesis that the wound channel and ballistic pressure wave effects each have an associated independent probability of incapacitation. Combining models for these two independent probabilities using the elementary rules of probability and performing a least-squares fit to the Marshall and Sanow data provides an empirical model with only two adjustable parameters for modeling bullet effectiveness with a standard error of 5.6% and a correlation coefficient R = 0.939. This supports the hypothesis that wound channel and pressure wave effects are independent (within the experimental error), and it also allows assignment of the relative contribution of each effect for a given handgun load. This mode...

  17. Metamaterials for Ballistic Electrons

    CERN Document Server

    Dragoman, D; Dragoman, Daniela; Dragoman, Mircea

    2007-01-01

    The paper presents a metamaterial for ballistic electrons, which consists of a quantum barrier formed in a semiconductor with negative effective electron mass. This barrier is the analogue of a metamaterial for electromagnetic waves in media with negative electrical permittivity and magnetic permeability. Besides applications similar to those of optical metamaterials, a nanosized slab of a metamaterial for ballistic electrons, sandwiched between quantum wells of positive effective mass materials, reveals unexpected conduction properties, e.g. single or multiple room temperature negative differential conductance regions at very low voltages and with considerable peak-to-valley ratios, while the traversal time of ballistic electrons can be tuned to larger or smaller values than in the absence of the metamaterial slab. Thus, slow and fast electrons, analogous to slow and fast light, occur in metamaterials for ballistic electrons.

  18. Internal ballistics of recoilless high-low pressure guns using hepta-tubular powders

    Directory of Open Access Journals (Sweden)

    M. C. Gupta

    1960-04-01

    Full Text Available In this paper, the theory of recoilless high-low pressure guns has been discussed by taking the form function and the results have been applied to the case of hepta-tubular powders. The results for high-low pressure guns follow as a particular case.

  19. Ballistic Imaging of High-Pressure Fuel Sprays using Incoherent, Ultra- short Pulsed Illumination with an Ultrafast OKE-based Time Gating

    CERN Document Server

    Purwar, Harsh; Rozé, Claude; Blaisot, Jean-Bernard

    2015-01-01

    We present an optical Kerr effect based time-gate with the collinear incidence of the pump and probe beams at the Kerr medium, liquid carbon disulfide, for ballistic imaging of the high-pressure fuel sprays. The probe pulse used to illuminate the object under study is extracted from the supercontinuum generated by tightly focusing intense femtosecond laser pulses inside water, thereby destroying their coherence. The optical imaging spatial resolution and gate timings are investigated and compared with a similar setup without supercontinuum generation, where the probe is still coherent. And finally, a few ballistic images of the fuel sprays using coherent and incoherent illumination with the proposed time-gate are presented and compared qualitatively.

  20. Uplift Pressure of Waves on A Horizontal Plate

    Institute of Scientific and Technical Information of China (English)

    周益人; 陈国平; 黄海龙; 王登婷

    2003-01-01

    Uplift pressures of waves acting on horizontal plates are the important basis for design of maritime hollow-trussed structures. In this paper, an experimental study on the uplift pressures of waves on a horizontal plate is conducted by use of a series of model tests. Detailed analysis has been given to the formation mechanism of uplift pressures of waves. It is considered that the impact pressure intensity is mainly affected by geometrical factors (tangential angle of waves), dynamic factors (wave height, wave velocity, etc.) and air cushion. Based on the test results, an equation for calculation of the maximum uplift pressure intensity of waves on a plate is presented. A large quantity of test data shows good agreement of the present equation with the test results.

  1. Measuring Projectile Velocity using Shock Wave Pressure Sensors

    Directory of Open Access Journals (Sweden)

    Sankarsan Padhy

    2014-11-01

    Full Text Available This paper deals with development of velocity measurement methodology based on projectile shock wave pressure measurements. The measurement principle is based on the fact that, whenever a projectile moves with supersonic velocity, shock wave fronts are produced along the trajectory of the projectile. Measurement configuration has been developed for measuring the shock wave pressure associated with projectile in flight, and hence, projectile velocity has been calculated. This paper covers various aspects of shock waves, generation of N Waves, feasibility study for capturing shock wave using dynamic microphone. Finally, suitable piezo-electric sensor has been selected and deployed in the trials and shock wave signature has been captured. From shock wave pressure, the projectile velocity has been computed.Defence Science Journal, Vol. 64, No. 6, November 2014, pp.499-501, DOI:http://dx.doi.org/10.14429/dsj.64.8108

  2. Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

    Institute of Scientific and Technical Information of China (English)

    Makiko YONAMINE; Takanori USHIJIMA; Yoshiaki MIYAZATO; Mitsuharu MASUDA; Hiroshi KATANODA; Kazuyasu MATSUO

    2006-01-01

    In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation,and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves.The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.

  3. Change of guinea pig inner ear pressure by square wave middle ear cavity pressure variation

    NARCIS (Netherlands)

    Feijen, RA; Segenhout, JM; Albers, FWJ; Wit, HP

    2002-01-01

    The inner ear fluid pressure of guinea pigs was measured during square wave middle ear cavity pressure variation. Time constants were derived for the slopes of the inner ear pressure recovery curves after middle ear pressure change. A "single exponential" function did not fit well and therefore more

  4. Decay of weak pressure waves in a low-pressure tube

    Energy Technology Data Exchange (ETDEWEB)

    Takiya, Toshio; Terada, Yukihiro; Komura, Akio [Hitachi Zosen Corp., Osaka (Japan); Higashino, Fumio; Abe, Hideaki; Ando, Masami

    1997-05-01

    In this study, the characteristics of pressure wave propagation in a vacuum tube have been investigated experimentally from the viewpoint of vacuum protection in the beamlines of a synchrotron radiation facility. Baffle plates having a single orifice of 5, 10 or 15 mm in diameter were installed in shock tubes 5 m in length and 36.6 or 68.8 mm in diameter, in order to slow the pressure wave or shock wave propagation, as a model for the beamline. To evaluate the decay of pressure waves, pressure changes with time at several locations along the side wall as well as at the end wall of the tube were measured. The results showed that the effect of the orifices on pressure wave propagation and its decay was significant. The present investigation may contribute to the design and construction of high-energy synchrotron radiation facilities with long beamlines. (author)

  5. Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power.

    Science.gov (United States)

    Mynard, Jonathan P; Smolich, Joseph J

    2016-04-15

    Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward wave-related components (ΠP±and ΠQ±). Wave power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics.

  6. Nonlinear Pressure Wave Analysis by Concentrated Mass Model

    Science.gov (United States)

    Ishikawa, Satoshi; Kondou, Takahiro; Matsuzaki, Kenichiro

    A pressure wave propagating in a tube often changes to a shock wave because of the nonlinear effect of fluid. Analyzing this phenomenon by the finite difference method requires high computational cost. To lessen the computational cost, a concentrated mass model is proposed. This model consists of masses, connecting nonlinear springs, connecting dampers, and base support dampers. The characteristic of a connecting nonlinear spring is derived from the adiabatic change of fluid, and the equivalent mass and equivalent damping coefficient of the base support damper are derived from the equation of motion of fluid in a cylindrical tube. Pressure waves generated in a hydraulic oil tube, a sound tube and a plane-wave tube are analyzed numerically by the proposed model to confirm the validity of the model. All numerical computational results agree very well with the experimental results carried out by Okamura, Saenger and Kamakura. Especially, the numerical analysis reproduces the phenomena that a pressure wave with large amplitude propagating in a sound tube or in a plane tube changes to a shock wave. Therefore, it is concluded that the proposed model is valid for the numerical analysis of nonlinear pressure wave problem.

  7. Distal shift of arterial pressure wave reflection sites with aging.

    Science.gov (United States)

    Sugawara, Jun; Hayashi, Koichiro; Tanaka, Hirofumi

    2010-11-01

    An early return of reflected waves, the backward propagation of the arterial pressure wave from the periphery to the heart, is associated with the augmentation of central pulse pressure and cardiovascular risks. The locations of arterial pressure wave reflection, along with arterial stiffening, have a major influence on the timing of the reflected wave. To determine the influence of aging on the location of a major reflection site, arterial length (via 3D artery tracing of MRI) and central (carotid-femoral) and peripheral (femoral-ankle) pulse wave velocities were measured in 208 adults varying in age. The major reflection site was detected by carotid-femoral pulse wave velocity and the reflected wave transit time (via carotid arterial pressure wave analysis). The length from the aortic valve to the major reflection site (eg, effective reflecting length) significantly increased with aging. The effective reflecting length normalized by the arterial length demonstrated that the major reflection sites were located between the aortic bifurcation and femoral site in most of the subjects. The normalized effective reflecting length did not alter with aging until 65 years of age and increased remarkably thereafter in men and women. The effective reflecting length was significantly and positively associated with the difference between central and peripheral pulse wave velocities (r=0.76). This correlation remained significant even when the influence of aortic pulse wave velocity was partial out (r=0.35). These results suggest that the major reflection site shifts distally with aging partly because of the closer matching of impedance provided by central and peripheral arterial stiffness.

  8. Acoustic wave propagation in high-pressure system.

    Science.gov (United States)

    Foldyna, Josef; Sitek, Libor; Habán, Vladimír

    2006-12-22

    Recently, substantial attention is paid to the development of methods of generation of pulsations in high-pressure systems to produce pulsating high-speed water jets. The reason is that the introduction of pulsations into the water jets enables to increase their cutting efficiency due to the fact that the impact pressure (so-called water-hammer pressure) generated by an impact of slug of water on the target material is considerably higher than the stagnation pressure generated by corresponding continuous jet. Special method of pulsating jet generation was developed and tested extensively under the laboratory conditions at the Institute of Geonics in Ostrava. The method is based on the action of acoustic transducer on the pressure liquid and transmission of generated acoustic waves via pressure system to the nozzle. The purpose of the paper is to present results obtained during the research oriented at the determination of acoustic wave propagation in high-pressure system. The final objective of the research is to solve the problem of transmission of acoustic waves through high-pressure water to generate pulsating jet effectively even at larger distances from the acoustic source. In order to be able to simulate numerically acoustic wave propagation in the system, it is necessary among others to determine dependence of the sound speed and second kinematical viscosity on operating pressure. Method of determination of the second kinematical viscosity and speed of sound in liquid using modal analysis of response of the tube filled with liquid to the impact was developed. The response was measured by pressure sensors placed at both ends of the tube. Results obtained and presented in the paper indicate good agreement between experimental data and values of speed of sound calculated from so-called "UNESCO equation". They also show that the value of the second kinematical viscosity of water depends on the pressure.

  9. Quantification of wave reflection using peripheral blood pressure waveforms.

    Science.gov (United States)

    Kim, Chang-Sei; Fazeli, Nima; McMurtry, M Sean; Finegan, Barry A; Hahn, Jin-Oh

    2015-01-01

    This paper presents a novel minimally invasive method for quantifying blood pressure (BP) wave reflection in the arterial tree. In this method, two peripheral BP waveforms are analyzed to obtain an estimate of central aortic BP waveform, which is used together with a peripheral BP waveform to compute forward and backward pressure waves. These forward and backward waves are then used to quantify the strength of wave reflection in the arterial tree. Two unique strengths of the proposed method are that 1) it replaces highly invasive central aortic BP and flow waveforms required in many existing methods by less invasive peripheral BP waveforms, and 2) it does not require estimation of characteristic impedance. The feasibility of the proposed method was examined in an experimental swine subject under a wide range of physiologic states and in 13 cardiac surgery patients. In the swine subject, the method was comparable to the reference method based on central aortic BP and flow. In cardiac surgery patients, the method was able to estimate forward and backward pressure waves in the absence of any central aortic waveforms: on the average, the root-mean-squared error between actual versus computed forward and backward pressure waves was less than 5 mmHg, and the error between actual versus computed reflection index was less than 0.03.

  10. Dual mode acoustic wave sensor for precise pressure reading

    Science.gov (United States)

    Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong

    2014-09-01

    In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.

  11. Generation of High Pressure and Temperature by Converging Detonation Waves

    Directory of Open Access Journals (Sweden)

    V. P. Singh

    1987-07-01

    Full Text Available Generation of high pressure and temperature has various applications in defence. Several techniques, viz flying plate method, collapsing of linear, convergence of detonation waves in solid explosives, have been established in this connection. In the present paper, converging detonation waves in solid explosives, where variable heat of detonation is being added to the front, is studied, by using Whitham's characteristics rule. Results are compared with those reported elsewhere.

  12. Generation of High Pressure and Temperature by Converging Detonation Waves

    OpenAIRE

    Singh, V. P.; Shukla, S K

    1987-01-01

    Generation of high pressure and temperature has various applications in defence. Several techniques, viz flying plate method, collapsing of linear, convergence of detonation waves in solid explosives, have been established in this connection. In the present paper, converging detonation waves in solid explosives, where variable heat of detonation is being added to the front, is studied, by using Whitham's characteristics rule. Results are compared with those reported elsewhere.

  13. Generation of high pressure and temperature by converging detonation waves

    Science.gov (United States)

    Singh, V. P.; Shukla, S. K.

    1987-07-01

    Generation of high pressure and temperature has various applications in defense. Several techniques, viz flying plate method, collapsing of linear, convergence of detonation waves in solid explosives, have been established in this connection. In this paper, converging detonation waves in solid explosives, where variable heat of detonation is being added to the front, are studied by using Whitham's characteristics rule. Results are compared with those reported elsewhere.

  14. Terminal ballistics

    CERN Document Server

    Rosenberg, Zvi

    2016-01-01

    This book comprehensively discusses essential aspects of terminal ballistics, combining experimental data, numerical simulations and analytical modeling. Employing a unique approach to numerical simulations as a measure of sensitivity for the major physical parameters, the new edition also includes the following features: new figures to better illustrate the problems discussed; improved explanations for the equation of state of a solid and for the cavity expansion process; new data concerning the Kolsky bar test; and a discussion of analytical modeling for the hole diameter in a thin metallic plate impacted by a shaped charge jet. The section on thick concrete targets penetrated by rigid projectiles has now been expanded to include the latest findings, and two new sections have been added: one on a novel approach to the perforation of thin concrete slabs, and one on testing the failure of thin metallic plates using a hydrodynamic ram.

  15. Ultrasonic wave based pressure measurement in small diameter pipeline.

    Science.gov (United States)

    Wang, Dan; Song, Zhengxiang; Wu, Yuan; Jiang, Yuan

    2015-12-01

    An effective non-intrusive method of ultrasound-based technique that allows monitoring liquid pressure in small diameter pipeline (less than 10mm) is presented in this paper. Ultrasonic wave could penetrate medium, through the acquisition of representative information from the echoes, properties of medium can be reflected. This pressure measurement is difficult due to that echoes' information is not easy to obtain in small diameter pipeline. The proposed method is a study on pipeline with Kneser liquid and is based on the principle that the transmission speed of ultrasonic wave in pipeline liquid correlates with liquid pressure and transmission speed of ultrasonic wave in pipeline liquid is reflected through ultrasonic propagation time providing that acoustic distance is fixed. Therefore, variation of ultrasonic propagation time can reflect variation of pressure in pipeline. Ultrasonic propagation time is obtained by electric processing approach and is accurately measured to nanosecond through high resolution time measurement module. We used ultrasonic propagation time difference to reflect actual pressure in this paper to reduce the environmental influences. The corresponding pressure values are finally obtained by acquiring the relationship between variation of ultrasonic propagation time difference and pressure with the use of neural network analysis method, the results show that this method is accurate and can be used in practice.

  16. Influence of ambient air pressure on impact pressure caused by breaking waves

    NARCIS (Netherlands)

    Moutzouris, C.

    1979-01-01

    Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing engin

  17. Dynamic Wave Pressures on Deeply Embedded Large Cylindrical Structures due to Random Waves

    Institute of Scientific and Technical Information of China (English)

    刘海笑; 唐云; 周锡礽

    2003-01-01

    The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves, and accordingly to offer valuable findings for engineering, the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different embedment depths in response to two wave spectra.The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain. By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder, experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory, and detailed comparisons were also carried out between the single and continuous cylinders. Some new findings and the corresponding analysis are reported in present paper. The investigation on continuous cylinders will be used in particular for reference in engineering applications because information is scarce on studying such kind of problem both analytically and experimentally.

  18. Utilization of sparker induced pressure waves to tenderize meat

    Science.gov (United States)

    This study investigated the feasibility of tenderizing meat using high pressure waves generated from a sparker source. Beef strip loins were cut into steaks from the anterior end and one to two steaks from each strip loin were randomly selected to serve as non-treated controls and the remaining ste...

  19. Ion Acceleration by the Radiation Pressure of Slow Electromagnetic Wave

    CERN Document Server

    Bulanov, S V; Kando, M; Pegoraro, F; Bulanov, S S; Geddes, C G R; Schroeder, C; Esarey, E; Leemans, W

    2012-01-01

    When the ions are accelerated by the radiation pressure of the laser pulse, their velocity can not exceed the laser group velocity, in the case when it is less than the speed of light in vacuum. This is demonstrated in two cases corresponding to the thin foil target irradiated by a high intensity laser light and to the hole boring by the laser pulse in the extended plasma accompanied by the collisionless shock wave formation. It is found that the beams of accelerated at the collisionless shock wave front ions are unstable against the Buneman-lke and the Weibel-like instabilities which result in the ion energy spectrum broadening.

  20. Ballistics for the neurosurgeon.

    Science.gov (United States)

    Jandial, Rahul; Reichwage, Brett; Levy, Michael; Duenas, Vincent; Sturdivan, Larry

    2008-02-01

    Craniocerebral injuries from ballistic projectiles are qualitatively different from injuries in unconfined soft tissue with similar impact. Penetrating and nonpenetrating ballistic injuries are influenced not only by the physical properties of the projectile, but also by its ballistics. Ballistics provides information on the motion of projectiles while in the gun barrel, the trajectory of the projectile in air, and the behavior of the projectile on reaching its target. This basic knowledge can be applied to better understand the ultimate craniocerebral consequences of ballistic head injuries.

  1. Shock wave velocity and shock pressure for low density powders : A novel approach

    NARCIS (Netherlands)

    Dijken, D.K.; Hosson, J.Th.M. De

    1994-01-01

    A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new mod

  2. SHOCK-WAVE VELOCITY AND SHOCK PRESSURE FOR LOW-DENSITY POWDERS - A NOVEL-APPROACH

    NARCIS (Netherlands)

    DIJKEN, DK; DEHOSSON, JTM

    1994-01-01

    A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new mod

  3. Evaluation and performance enhancement of a pressure transducer under flows, waves, and a combination of flows and waves

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, J.A.E.; Foden, P.; Taylor, K.; McKeown, J.; Desa, E.

    The performance of a pressure transducer, with its inlet attached to differing hydromechanical front ends, has been evaluated in flow flume and wave flume experiments in which laminar and turbulent flows, and regular progressive gravity waves...

  4. Pressure wave model for action potential propagation in excitable cells

    CERN Document Server

    Rvachev, M M

    2003-01-01

    Speed of propagation of small-amplitude pressure waves through the cytoplasmic interior of myelinated and unmyelinated axons of different diameters is theoretically estimated and is found to generally agree with the action potential (AP) conduction velocities. This remarkable coincidence allows to surmise a model in which AP spread along axon is propelled not by straggling ionic currents as in the widely accepted local circuit theory, but by mechanoactivation of the membrane ion channels by a traveling pressure pulse. Hydraulic pulses propagating in the viscous axoplasm are calculated to decay over ~1 mm distances, and it is further hypothesized that it is the role of influxing during the AP calcium ions to activate membrane skeletal protein network attached to the membrane cytoplasmic side for a brief radial contraction amplifying the pressure pulse and preventing its decay. The model correctly predicts that the AP conduction velocity should vary as the one-half power of axon diameter for large unmyelinated ...

  5. A new technique for assessing arterial pressure wave forms and central pressure with tissue Doppler

    Science.gov (United States)

    Haluska, Brian A; Jeffriess, Leanne; Mottram, Phillip M; Carlier, Stephane G; Marwick, Thomas H

    2007-01-01

    Background Non-invasive assessment of arterial pressure wave forms using applanation tonometry of the radial or carotid arteries can be technically challenging and has not found wide clinical application. 2D imaging of the common carotid arteries is routinely used and we sought to determine whether arterial waveform measurements could be derived from tissue Doppler imaging (TDI) of the carotid artery. Methods We studied 91 subjects (52 men, age 52 ± 14 years) with and without cardiovascular disease. Tonometry was performed on the carotid artery simultaneously with pulsed wave Doppler of the LVOT and acquired digitally. Longitudinal 2D images of the common carotid artery with and without TDI were also acquired digitally and both TDI and tonometry were calibrated using mean and diastolic cuff pressure and analysed off line. Results Correlation between central pressure by TDI and tonometry was excellent for maximum pressure (r = 0.97, p < 0.0001). The mean differences between central pressures derived by TDI and tonometry were minimal (systolic 5.36 ± 5.5 mmHg; diastolic 1.2 ± 1.2 mmHg). Conclusion Imaging of the common carotid artery motion with tissue Doppler may permit acquisition of a waveform analogous to that from tonometry. This method may simplify estimation of central arterial pressure and calculation of total arterial compliance. PMID:17266772

  6. Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

    Energy Technology Data Exchange (ETDEWEB)

    IceCube Collaboration; Klein, Spencer

    2009-06-04

    We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.

  7. Pressure Distribution for Piezoelectric Extracorporeal Shock Wave Lithotripsy

    Science.gov (United States)

    Yanagida, Yuji; Iwama, Nobuyuki; Okazaki, Kiyoshi

    1993-05-01

    The objective of this study is to develop a safer and more effective extracorporeal shock wave lithotripter. The first stage of the study shows the sound pressure field of the shock wave made by an ECHOLITH ESL-500A. The sound pressure distribution is in a ring configuration on a 60 mm plane in front of the focal plane. As the plane approaches the focal plane, the sound pressure relatively increases at the cross point with the axis of the transducer and decreases at the ring. The focal zone is 2.5 mm × 16.1 mm at 60 V driving voltage and 1.8 mm × 14.2 mm at “INTENSITY 2.” In the next stage we propose a method for changing the field by electronic driving control of each piezoceramic element for effective therapy. The focal zone can be changed from 3.1 mm × 19.1 mm to 3.9 mm × 32.4 mm at 60 V driving voltage with this method. These focal zones are calculated by means of computer simulation.

  8. 骨科弹道式冲击波配合中药熏洗治疗软组织劳损%Orthopedic ballistic shock wave and herbal fumigation therapy for treatment of overuse injury of soft tissue

    Institute of Scientific and Technical Information of China (English)

    刘波; 刘辉; 赵卫侠; 伍萨

    2011-01-01

    BACKGROUND: Orthopedic ballistic shock wave is commonly used to cure the overuse injury of soft tissues, but this therapy combined with herbal fumigation simultaneously is rarely reported.OBJECTIVE: To observe the clinical effects of the orthopedic ballistic shock wave combined with Chinese medicinal herbal fumigation on overuse injury of soft tissues.METHODS: A total of 912 cases with soft tissue overuse injury were treated with the orthopedic ballistic shock wave and Chinese medicinal herbal fumigation. The pain intensity of trigger point was assessed by visual analogue scale.RESULTS AND CONCLUSION: The intensity of pain decreased obviously after one weak treatment, but there were no significant changes of visual analogue scale in the second week. Two weeks later, the intensity of pain decreased significantly compared with before treatment (P < 0.05). Compared with tennis elbow and tenovaginitis of flexor digitorum, the visual analogue scale of calcanodynia decreased slowly (P < 0.05). The therapy of orthopedic ballistic shock wave and herbal fumigation is significantly efficient for overuse injury of soft tissues.%背景:目前采用骨科弹道式冲击波治疗软组织劳损较为普遍,但与中药熏洗配合治疗的报道甚少.目的:观察骨科弹道式冲击波配合中药熏洗治疗软组织劳损的临床疗效.方法:将912 例软组织劳损患者采用骨科弹道式冲击波配合中药熏洗治疗.采用目测类比定级法评定患者痛点受压时的疼痛强度.结果与结论:经骨科弹道式冲击波配合中药熏洗治疗1周后,患者疼痛下降明显,第2周时测类比定级法评分变化不明显.2 周以后,患者疼痛强度与治疗前比较明显下降(P < 0.05).跟痛症与网球肘、屈指肌腱腱鞘炎比较,患者疼痛强度下降缓慢(P < 0.05).结果证实,骨科弹道式冲击波配合中药熏洗治疗软组织劳损疗效显著.

  9. Tunnel pressure waves - A smartphone inquiry on rail travel

    Science.gov (United States)

    Müller, Andreas; Hirth, Michael; Kuhn, Jochen

    2016-02-01

    When traveling by rail, you might have experienced the following phenomenon: The train enters a tunnel, and after some seconds a noticeable pressure change occurs, as perceived by your ears or even by a rapid wobbling of the train windows. The basic physics is that pressure waves created by the train travel down the tunnel, are reflected at its other end, and travel back until they meet the train again. Here we will show (i) how this effect can be well understood as a kind of large-scale outdoor case of a textbook paradigm, and (ii) how, e.g., a prediction of the tunnel length from the inside of a moving train on the basis of this model can be validated by means of a mobile phone measurement.

  10. Simulations of nonlinear continuous wave pressure fields in FOCUS

    Science.gov (United States)

    Zhao, Xiaofeng; Hamilton, Mark F.; McGough, Robert J.

    2017-03-01

    The Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation is a parabolic approximation to the Westervelt equation that models the effects of diffraction, attenuation, and nonlinearity. Although the KZK equation is only valid in the far field of the paraxial region for mildly focused or unfocused transducers, the KZK equation is widely applied in medical ultrasound simulations. For a continuous wave input, the KZK equation is effectively modeled by the Bergen Code [J. Berntsen, Numerical Calculations of Finite Amplitude Sound Beams, in M. F. Hamilton and D. T. Blackstock, editors, Frontiers of Nonlinear Acoustics: Proceedings of 12th ISNA, Elsevier, 1990], which is a finite difference model that utilizes operator splitting. Similar C++ routines have been developed for FOCUS, the `Fast Object-Oriented C++ Ultrasound Simulator' (http://www.egr.msu.edu/˜fultras-web) to calculate nonlinear pressure fields generated by axisymmetric flat circular and spherically focused ultrasound transducers. This new routine complements an existing FOCUS program that models nonlinear ultrasound propagation with the angular spectrum approach [P. T. Christopher and K. J. Parker, J. Acoust. Soc. Am. 90, 488-499 (1991)]. Results obtained from these two nonlinear ultrasound simulation approaches are evaluated and compared for continuous wave linear simulations. The simulation results match closely in the farfield of the paraxial region, but the results differ in the nearfield. The nonlinear pressure field generated by a spherically focused transducer with a peak surface pressure of 0.2MPa radiating in a lossy medium with β = 3.5 is simulated, and the computation times are also evaluated. The nonlinear simulation results demonstrate acceptable agreement in the focal zone. These two related nonlinear simulation approaches are now included with FOCUS to enable convenient simulations of nonlinear pressure fields on desktop and laptop computers.

  11. Experimental investigation of wave-driven pore-water pressure and wave attenuation in a sandy seabed

    Directory of Open Access Journals (Sweden)

    Jisheng Zhang

    2016-06-01

    Full Text Available Wave–seabed interaction has become a big concern of coastal researchers and engineers in the past decades as it may largely contribute to the seabed instability and failure of marine foundations. A series of laboratory experiments are carried out in a wave flume to study the wave-driven pore-water pressure in a sandy seabed and the attenuation of wave height. Waves propagating over a sandy seabed lead to oscillatory excess pore-water pressures within the porous seabed. Amplitude of pore-water pressure within the seabed decreases toward the bottom. A phase lag of pore-water pressure is clearly observed, and it contributes to net upward pressure related to seabed instability. Height of the incident wave is reduced as part of wave energy is dissipated by bottom friction, and a maximum attenuation of the incident wave height is up to 7.23% in the experiments. The influences of wave period and height of the incident wave on pore-water pressure and wave attenuation are also analyzed and discussed.

  12. Impact Pressure of Incident Regular Waves and Irregular Waves on the Subface of Open-Piled Structures

    Institute of Scientific and Technical Information of China (English)

    任冰; 王永学

    2004-01-01

    This paper presents the results of comparison of impact pressures on open-plied structures induced by regular waves and irregular waves in a laboratory channel. Regular waves with wave heights ranging from 0.1 ~ 0.2 m and periods ranging from 1.0 ~ 2.0 s are tested. The target spectrm for the irregular wave is JONSWAP spectrum. Irregular waves with significant wave heights in the range of 0.10 ~ 0.25 m and peak periods in the range of 1.0 ~ 2.0 s are tested. The relative clearance s/H1/3(H) is between - 0.1 and 0.4, s being the subface level of structure model above the still water level. Time series of impact pressure are analyzed to indicate whether the property of impact pressures induced by the regular wave significantly deviates from that by the irregular wave. The distribution of the impact pressure along the underside of the structure is compared for different types of incident waves. The effects of wave parameters, structure dimension and structure clearance on the impact pressure are also discussed.

  13. Decay of weak pressure waves in a low pressure tube; Teiatsu kannai ni okeru bisho atsuryokuha no gensui

    Energy Technology Data Exchange (ETDEWEB)

    Takiya, T.; Terada, Y.; Komura, A. [Hitachi Zosen Corp., Osaka (Japan); Higashino, F.; Abe, H. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Faculty of Technology; Abe, M. [National Lab. for High Energy Physics, Tsukuba (Japan)

    1996-04-25

    The characteristics of pressure wave propagation in a vacuum tube have been investigated experimentally from the viewpoint of vacuum protection in the beam lines of a synchrotrons radiation facility. Baffle plates having a single orifice of 5, 10 or 15 mm in diameter were installed in shock tubes 5 m in length, and 36.6 or 68.8 mm in diameter, in order to show the pressure wave or shock wave propagation as a model for the beam line. To evaluate the decay of pressure waves pressure changes with time at several locations along the side wall as well as at the end wall of the tube were measured. The results show that the effect of the orifices on pressure wave propagation and its decay is significant. The present investigation may contribute to the design and construction of high energy synchrotrons radiation facilities with long beam lines. 11 refs., 9 figs., 2 tabs.

  14. Wave-Induced Pressure Under an Internal Solitary Wave and Its Impact at the Bed

    Science.gov (United States)

    Rivera, Gustavo; Diamesis, Peter; Jenkins, James; Berzi, Diego

    2015-11-01

    The bottom boundary layer (BBL) under a mode-1 internal solitary wave (ISW) of depression propagating against an oncoming model barotropic current is examined using 2-D direct numerical simulation based on a spectral multidomain penalty method model. Particular emphasis is placed on the diffusion into the bed of the pressure field driven by the wake and any near-bed instabilities produced under specific conditions. To this end, a spectral nodal Galerkin approach is used for solving the diffusion equation for the wave-induced pressure. At sufficiently high ISW amplitude, the BBL undergoes a global instability which produces intermittent vortex shedding from within the separation bubble in the lee of the wave. The interplay between the bottom shear stress field and pressure perturbations during vortex ejection events and the subsequent evolution of the vortices is examined. The potential for bed failure upon the passage of the ISW trough and implications for resuspension of bottom particulate matter are both discussed in the context of specific sediment transport models.

  15. An Inexpensive Arterial Pressure Wave Sensor and its application in different physiological condition

    CERN Document Server

    Sur, S; Sur, Shantanu

    2005-01-01

    Arterial Blood Pressure wave monitoring is considered to be important in assessment of cardiovascular system. We developed a novel pulse wave detection system using low frequency specific piezoelectric material as pressure wave sensor. The transducer detects the periodic change in the arterial wall diameter produced by pressure wave and the amplified signal after integration represents the pressure wave. The signal before integration is proportional to the rate of change of pressure wave and it not only reproduces the pressure waveform faithfully, but also its sharper nature helps to reliably detect the heart period variability (HPV). We have studied the position-specific (e.g. over carotid or radial artery) nature of change of this pulse wave signal (shape and amplitude) and also the changes at different physiological states.

  16. A Comparison of Measured and Predicted Wave-Impact Pressures from Breaking and Non-breaking Waves

    CERN Document Server

    Fullerton, Anne M; Brewton, Susan; Brucker, Kyle A; O'Shea, Thomas T; Dommermuth, Douglas G

    2014-01-01

    Impact loads from waves on vessels and coastal structures are complex and may involve wave breaking, which has made these loads difficult to estimate numerically or empirically. Results from previous experiments have shown a wide range of forces and pressures measured from breaking and nonbreaking waves, with no clear trend between wave characteristics and the localized forces and pressures that they generate. In 2008, a canonical breaking wave impact data set was obtained at the Naval Surface Warfare Center, Carderock Division, by measuring the distribution of impact pressures of incident nonbreaking and breaking waves on one face of a cube. This experimental effort was sponsored by the Office of Naval Research (ONR), under the Dynamics of Interacting Platforms Program, Program Manager Dr. Ron Joslin. The effects of wave height, wavelength, face orientation, face angle, and submergence depth were investigated. Additionally, a limited number of runs were made at low forward speeds, ranging from about 0.5 to 2...

  17. Wave-induced stresses and pore pressures near a mudline

    Directory of Open Access Journals (Sweden)

    Andrzej Sawicki

    2008-12-01

    Full Text Available Conventional methods for the determination of water-wave induced stresses inseabeds composed of granular soils are based on Biot-type models, in which the soilskeleton is treated as an elastic medium. Such methods predict effective stressesin the soil that are unacceptable from the physical point of view, as they permittensile stresses to occur near the upper surface of the seabed. Therefore, in thispaper the granular soil is assumed to behave as an elastic-ideally plastic material,with the Coulomb-Mohr yield criterion adopted to bound admissible stress states inthe seabed. The governing equations are solved numerically by a~finite differencemethod. The results of simulations, carried out for the case of time-harmonicwater waves, illustrate the depth distributions of the excess pore pressures and theeffective stresses in the seabed, and show the shapes of zones of soil in the plastic state.~In particular, the effects on the seabed behaviour of suchparameters as the degree of pore water saturation, the soil permeability, and theearth pressure coefficient, are illustrated.

  18. Mathematical Modeling of the Pressure Field Generated by Ocean Wave at the Bottom of the Ocean

    Institute of Scientific and Technical Information of China (English)

    龚沈光; 唐劲飞; 颜冰

    2002-01-01

    This paper develops a new method for calculating the pressure-tirme processof the pressure field generated by ocean wave at sea bottom based on the surface wavespectrum of the ocean wave. The basic assumptions of modeling are that the surfaceocean wave pressure equals to the atmospheric pressure and that the viscidity of seawater is neglected. The steps of modeling are described below. First the power spectraldensity of ocean wave is discretized and the amplitude spectra of harmonic ocean waveare obtained. Then the amplitude spectra of harmonic pressure are obtained accordingto the amplitude spectrum of surface wave and the depth of the sea. Finally, based onthe oceanographic theory of representing a fixed wave surface by summing up random-phase sinusoids, the pressure-time process of pressure field at sea bottom is obtained bysumming up the amplitude spectrum of pressure. The paper also develops a method ofdetermining the relationship between mean wave period and wave heights undershallow water condition, thus the pressure-time process of pressure field produced bynon-well-developed ocean wave can be directly calculated once the mean wave heightand period are known.

  19. The Truth About Ballistic Coefficients

    CERN Document Server

    Courtney, Michael

    2007-01-01

    The ballistic coefficient of a bullet describes how it slows in flight due to air resistance. This article presents experimental determinations of ballistic coefficients showing that the majority of bullets tested have their previously published ballistic coefficients exaggerated from 5-25% by the bullet manufacturers. These exaggerated ballistic coefficients lead to inaccurate predictions of long range bullet drop, retained energy and wind drift.

  20. FAST TRACK COMMUNICATION: Small surface wave discharge at atmospheric pressure

    Science.gov (United States)

    Kiss'ovski, Zh; Kolev, M.; Ivanov, A.; Lishev, St.; Koleva, I.

    2009-09-01

    A small surface wave driven source produces plasma at atmospheric pressure. Microwave power at frequency 2.45 GHz is coupled with the source and a discharge is ignited at power levels below 10 W. The coaxial exciter of the surface waves has a length of 10 mm because its dielectric is a high permittivity discharge tube. The plasma source operates as a plasma jet in the case of plasma columns longer than the tube length. The source maintains stable plasma columns over a wide range of neutral gas flow and applied power in continuous and pulse regimes. An additional advantage of this source is the discharge self-ignition. An electron temperature of Te ~ 1.9 eV and a density of ne ~ 3.9 × 1014 cm-3 are estimated by the probe diagnostics method. The emission spectra in the wavelength range 200-1000 nm under different experimental conditions are analysed and they prove the applicability of the source for analytical spectroscopy. The dependences of column length, reflected power and plasma parameters on the gas flow and the input power are discussed.

  1. Effects of reverse waves on the hydrodynamic pressure acting on a dual porous horizontal plate

    Directory of Open Access Journals (Sweden)

    Kweon Hyuck-Min

    2014-03-01

    Full Text Available The seaward reverse wave, occurring on the submerged dual porous horizontal plate, can contribute to the reduction of the transmitted wave as it reflects the propagating wave. However, the collision between the propa¬gating and seaward reverse waves increases the water level and acts as a weight on the horizontal plate. This study investigated the characteristics of the wave pressure created by the seaward reverse wave through the analysis of expe¬rimental data. The analysis confirmed the following results: 1 the time series of the wave pressure showed reverse phase phenomena due to the collision, and the wave pressures acted simultaneously on both upper and lower surfaces of the horizontal plate; 2 the horizontal plate became repeatedly compressed and tensile before and after the occur¬rence of the seaward reverse wave; and 3 the seaward reverse wave created the total wave pressure to the maximum towards the direction of gravity, primarily on the upper plate. It was also confirmed that the wave distributions showed a similar trend to the wave steepness. Such outcome of the analysis will provide basic information to the structural analysis of the horizontal plate as a wave dissipater of the steel-type breakwater (STB.

  2. 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%.

  3. Experimental investigation on the wave-induced pore pressure around shallowly embedded pipelines

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of regular wave experiments have been done in a large-scale wave flume to investigate the wave-induced pore pressure around the submarine shallowly embedded pipelines. The model pipelines are buried in three kinds of soils, including gravel, sand and silt with different burial depth. The input waves change with height and period. The results show that the amplitudes of wave-induced pore pressure increase as the wave period increase, and decay from the surface to the bottom of seabed. Higher pore pressures are recorded at the pipeline top and the lower pore pressures at the bottom, especially in the sand seabed. The normalized pressure around pipeline decreases as the relative water depth, burial depth or scattering parameters increase. For the silt seabed, the wavelet transform has been successfully used to analyze the signals of wave-induced pore pressure, and the oscillatory and residual pore pressure can be extracted by wavelet analysis. Higher oscillatory pressures are recorded at the bottom and the lower pressures at the top of the pipeline. However, higher residual pressures are recorded at the top and the lower pressures at the bottom of the pipeline.

  4. Analysis on the Pressure Fluctuation Law of a Hydraulic Exciting System with a Wave-exciter

    Institute of Scientific and Technical Information of China (English)

    WEI Xiu-ye; KOU Zi-ming; LU Zi-rong

    2011-01-01

    A hydraulic exciting system with a wave exciter has been constructed in order to study the hydraulic vibra- tion law. The system consists of an oil source, wave-exciter and oil cylinder, and is controlled by a wave-exciter. The working principle of the hydraulic exciting system and wave exciter has been analyzed, and its excitation process has been illustrated. The law of every pipe's pressure fluctuation of the system is obtained by experiment. The theo- retical analysis and experimental data prove that the pipeline pressure periodically changes and the pipeline pressure fluctuation frequency is independently controlled by the excitation frequency of the wave-exciter. Every pipelinc's pressure wave is produced by system flow fluctuation and water hammer coupling. The pressure fluctuation rules of the system provide a theoretical basis for the study of the associated liberation system.

  5. Ballistic Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Ballistic Test Facility is comprised of two outdoor and one indoor test ranges, which are all instrumented for data acquisition and analysis. Full-size aircraft...

  6. An application of Love SH waves for the viscosity measurement of triglycerides at high pressures

    Science.gov (United States)

    Rostocki, A. J.; Siegoczyński, R. M.; Kiełczyński, P.; Szalewski, M.

    2010-03-01

    A new ultrasonic method of viscosity measurements at a high-pressure conditions has been presented. The method is based on the Love wave amplitude measurement. The same electronic setup as in the Bleustein-Gulyaev (B-G) wave method applied by the authors recently for a high-pressure measurement was adopted. The new sensors were made of metallic materials, which make them more reliable at high-pressure conditions. The method has been successfully applied for the viscosity measurement of some triglycerides at high-pressure conditions up to 1 GPa. The results have been compared with the earlier results obtained using B-G waves. This comparison has shown that Love wave method sensors are more reliable than B-G wave sensors and are also cheaper in fabrication, although the sensitivity of Love wave sensors is lower. During the measurement, the phase transitions in the investigated liquids were observed.

  7. Predicting S-wave velocities for unconsolidated sediments at low effective pressure

    Science.gov (United States)

    Lee, Myung W.

    2010-01-01

    Accurate S-wave velocities for shallow sediments are important in performing a reliable elastic inversion for gas hydrate-bearing sediments and in evaluating velocity models for predicting S-wave velocities, but few S-wave velocities are measured at low effective pressure. Predicting S-wave velocities by using conventional methods based on the Biot-Gassmann theory appears to be inaccurate for laboratory-measured velocities at effective pressures less than about 4-5 megapascals (MPa). Measured laboratory and well log velocities show two distinct trends for S-wave velocities with respect to P-wave velocity: one for the S-wave velocity less than about 0.6 kilometer per second (km/s) which approximately corresponds to effective pressure of about 4-5 MPa, and the other for S-wave velocities greater than 0.6 km/s. To accurately predict S-wave velocities at low effective pressure less than about 4-5 MPa, a pressure-dependent parameter that relates the consolidation parameter to shear modulus of the sediments at low effective pressure is proposed. The proposed method in predicting S-wave velocity at low effective pressure worked well for velocities of water-saturated sands measured in the laboratory. However, this method underestimates the well-log S-wave velocities measured in the Gulf of Mexico, whereas the conventional method performs well for the well log velocities. The P-wave velocity dispersion due to fluid in the pore spaces, which is more pronounced at high frequency with low effective pressures less than about 4 MPa, is probably a cause for this discrepancy.

  8. a Low Cost Pressure Wave Generator Using Diaphragms

    Science.gov (United States)

    Caughley, A. J.; Haywood, D. J.; Wang, C.

    2008-03-01

    The high cost of Pressure Wave Generators (PWGs) is a major barrier to the more widespread use of high-efficiency pulse tube and Stirling cryocoolers. This paper describes the development and testing of a low-cost industrial-style PWG which employs metal diaphragms. The use of diaphragms removes the need for rubbing or clearance seals, and eliminates contamination problems by hermetically separating the gas circuit and the lubricated driving mechanism. A conventional low-cost electric motor is used for power input, via a novel high-efficiency kinematic linkage. A first prototype of the diaphragm PWG produced 3.2 kW of PV power with a measured electro-acoustic efficiency of 72%. Accelerated testing predicts a diaphragm life time in excess of 40,000 hours. An additional advantage of the use of diaphragms is the ability to directly cool the gas in the compression space. This eliminates or significantly reduces the requirement for an after cooler, and further decreases the cost of the whole cryocooler system. A pulse tube cryocooler has been successfully run at Industrial Research Ltd to 59K with the diaphragm PWG and no aftercooler. Another pulse tube cryocooler with the diaphragm PWG is undergoing development at Cryomech, the results of which will be given in another presentation.

  9. Role of the vertical pressure gradient in wave boundary layers

    DEFF Research Database (Denmark)

    Jensen, Karsten Lindegård; Sumer, B. Mutlu; Vittori, Giovanna

    2014-01-01

    By direct numerical simulation (DNS) of the flow in an oscillatory boundary layer, it is possible to obtain the pressure field. From the latter, the vertical pressure gradient is determined. Turbulent spots are detected by a criterion involving the vertical pressure gradient. The vertical pressur...

  10. A Non-Intrusive Pressure Sensor by Detecting Multiple Longitudinal Waves.

    Science.gov (United States)

    Zhou, Hongliang; Lin, Weibin; Ge, Xiaocheng; Zhou, Jian

    2016-08-05

    Pressure vessels are widely used in industrial fields, and some of them are safety-critical components in the system-for example, those which contain flammable or explosive material. Therefore, the pressure of these vessels becomes one of the critical measurements for operational management. In the paper, we introduce a new approach to the design of non-intrusive pressure sensors, based on ultrasonic waves. The model of this sensor is built based upon the travel-time change of the critically refracted longitudinal wave (LCR wave) and the reflected longitudinal waves with the pressure. To evaluate the model, experiments are carried out to compare the proposed model with other existing models. The results show that the proposed model can improve the accuracy compared to models based on a single wave.

  11. Cardiac output in idiopathic normal pressure hydrocephalus: association with arterial blood pressure and intracranial pressure wave amplitudes and outcome of shunt surgery

    Directory of Open Access Journals (Sweden)

    Eide Per K

    2011-02-01

    Full Text Available Abstract Background In patients with idiopathic normal pressure hydrocephalus (iNPH responding to shunt surgery, we have consistently found elevated intracranial pressure (ICP wave amplitudes during diagnostic ICP monitoring prior to surgery. It remains unknown why ICP wave amplitudes are increased in these patients. Since iNPH is accompanied by a high incidence of vascular co-morbidity, a possible explanation is that there is reduced vascular compliance accompanied by elevated arterial blood pressure (ABP wave amplitudes and even altered cardiac output (CO. To investigate this possibility, the present study was undertaken to continuously monitor CO to determine if it is correlated to ABP and ICP wave amplitudes and the outcome of shunting in iNPH patients. It was specifically addressed whether the increased ICP wave amplitudes seen in iNPH shunt responders were accompanied by elevated CO and/or ABP wave amplitude levels. Methods Prospective iNPH patients (29 were clinically graded using an NPH grading scale. Continuous overnight minimally-invasive monitoring of CO and ABP was done simultaneously with ICP monitoring; the CO, ABP, and ICP parameters were parsed into 6-second time windows. Patients were assessed for shunt surgery on clinical grade, Evan's index, and ICP wave amplitude. Follow-up clinical grading was performed 12 months after surgery. Results ICP wave amplitudes but not CO or ABP wave amplitude, showed good correlation with the response to shunt treatment. The patients with high ICP wave amplitude did not have accompanying high levels of CO or ABP wave amplitude. Correlation analysis between CO and ICP wave amplitudes in individual patients showed different profiles [significantly positive in 10 (35% and significantly negative in 16 (55% of 29 recordings]. This depended on whether there was also a correlation between ABP and ICP wave amplitudes and on the average level of ICP wave amplitude. Conclusions These results gave no

  12. Experimental Study and Numerical Modeling of Wave Induced Pore Pressure Attenuation Inside a Rubble Mound Breakwater

    DEFF Research Database (Denmark)

    Troch, Peter; Rouck, Julien De; Burcharth, Hans Falk

    2003-01-01

    The main objective of this paper is to study the attenuation of the wave induced pore pressures inside the core of a rubble mound breakwater. The knowledge of the distribution and the attenuation of the pore pressures is important for the design of a stable and safe breakwater. The pore pressure...

  13. The Importance of Pressure Sampling Frequency in Models for Determination of Critical Wave Loadings on Monolithic Structures

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Andersen, Thomas Lykke; Meinert, Palle

    2008-01-01

    Wave induced pressures on model scale monolithic structures like caissons and concrete superstructures on rubble mound breakwaters show very peaky variations, even in cases without impacts from slamming waves.......Wave induced pressures on model scale monolithic structures like caissons and concrete superstructures on rubble mound breakwaters show very peaky variations, even in cases without impacts from slamming waves....

  14. Clinical review: Interpretation of arterial pressure wave in shock states

    OpenAIRE

    Lamia, Bouchra; Chemla, Denis; Richard, Christian; Teboul, Jean-Louis

    2005-01-01

    In critically ill patients monitored with an arterial catheter, the arterial pressure signal provides two types of information that may help the clinician to interpret haemodynamic status better: the mean values of systolic, diastolic, mean and pulse pressures; and the magnitude of the respiratory variation in arterial pressure in patients undergoing mechanical ventilation. In this review we briefly discuss the physiological mechanisms responsible for arterial pressure generation, with specia...

  15. Harmonics tracking of intracranial and arterial blood pressure waves.

    Science.gov (United States)

    Shahsavari, Sima; McKelvey, Tomas

    2008-01-01

    Considering cardiorespiratory interaction and heart rate variability, a new approach is proposed to decompose intracranial pressure and arterial blood pressure to their different harmonics. The method is based on tracking the amplitudes of the harmonics by a Kalman filter based tracking algorithm. The algorithm takes benefit of combined frequency estimation technique which uses both Fast Fourier Transform and RR-interval detection. The result would be of use in intracranial pressure and arterial blood pressure waveform analysis as well as other investigations which need to estimate contribution of specific harmonic in above mentioned signals such as Pressure-Volume Compensatory Reserve assessment.

  16. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs. Spin-dependen

  17. Internal wave-turbulence pressure above sloping sea bottoms

    NARCIS (Netherlands)

    van Haren, H.

    2011-01-01

    An accurate bottom pressure sensor has been moored at different sites varying from a shallow sea strait via open ocean guyots to a 1900 m deep Gulf of Mexico. All sites show more or less sloping bottom topography. Focusing on frequencies (sigma) higher than tidal, the pressure records are remarkably

  18. Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.

    Science.gov (United States)

    Berkouk, K; Carpenter, P W; Lucey, A D

    2003-12-01

    Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.

  19. Effect of pressurization on helical guided wave energy velocity in fluid-filled pipes.

    Science.gov (United States)

    Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2017-03-01

    The effect of pressurization stresses on helical guided waves in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb waves in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided wave propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided wave modes. For this purpose, an expression for the energy velocity of leaky Lamb waves in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent variations in energy velocity with respect to stress. An experimental setup is designed for measuring variations in helical wave energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental variations in energy velocity for the helical guided waves and the theoretical leaky Lamb wave solutions.

  20. Characterization of the pressure wave originating in the explosion of a gas cloud

    Science.gov (United States)

    Essers, J. A.

    Models for predicting the effects of hydrocarbon explosions on nuclear power plants are discussed. By solving the Euler equations for simple one dimensional models, formulas predicting wave speed, induced flow velocity, reflected wave speed and overpressure as functions of the local value of incident wave overpressure are obtained. A simplified nonlinear isentropic potential flow model is proposed. Errors in predicting wave characteristics from this model or from classical linear acoustic models are evaluated. Formulas to predict the evolution of main pressure pulse characteristics are given. The time and distance required for the formation of a sharp pressure pulse and to obtain a significant spreading of expansion phase is assessed. The ability of models to accurately predict these deformations is discussed. The isentropic model leads to an excellent prediction of all wave characteristics if the overpressure is not very large. Except for very weak overpressures, the accuracy of acoustic models is poor.

  1. Vertical pressure gradient and particle motions in wave boundary layers

    DEFF Research Database (Denmark)

    Jensen, Karsten Lindegård

    The present study covers both a numerical and experimental investigation of the processes in the oscillatory boundary layer. In the first part a direct numerical simulation (DNS) is conducted to study the vertical pressure gradient, and its role in relation to laminar to turbulent transition...... and its role in the fully turbulent boundary layer. The pressure in the flow is obtained from the flow fields of the oscillatory boundary layer. What differs, the vertical pressure gradient, from other turbulent quantities, like e.g. velocity fluctuations is that it can detect newly generated turbulence....... This is in contrast to velocity fluctuations that are diffusive, so they can also contain residual turbulence from the previous half cycle until they are dissipated. Furthermore, the magnitude of the mean value of conditionally averaged vertical pressure gradient (for −∂p∗/∂x∗ 2 > 0) is compared to the submerged...

  2. Coastal Trapped Waves, Alongshore Pressure Gradients, and the California Undercurrent

    Science.gov (United States)

    2014-01-01

    D. NM W. J. Teague. C. N. Bairon. M. R. Carnes . and C. M. Lee. 2002: The Modular Ocean Dala Assimilation System (MODAS). J. Annoy Oieanic Tniwol...waves by irreimlarilies in coastline and topouraphy. J. llns. ()i»m<w.. 20." 396 421. Willmott. C J.. 1981: On the validation of models. Ph \\s. Gnffr

  3. New ultrasonic Bleustein-Gulyaev wave method for measuring the viscosity of liquids at high pressure

    Science.gov (United States)

    Kiełczyński, P.; Szalewski, M.; Siegoczyński, R. M.; Rostocki, A. J.

    2008-02-01

    In this paper, a new method for measuring the viscosity of liquids at high pressure is presented. To this end the authors have applied an ultrasonic method using the Bleustein-Gulyaev (BG) surface acoustic wave. By applying the perturbation method, we can prove that the change in the complex propagation constant of the BG wave produced by the layer of liquid loading the waveguide surface is proportional to the shear mechanical impedance of the liquid. In the article, a measuring setup employing the BG wave for the purpose of measuring the viscosity of liquids at high pressure (up to 1GPa) is presented. The results of high-pressure viscosity measurements of triolein and castor oil are also presented. In this paper the model of a Newtonian liquid was applied. Using this new method it is also possible to measure the viscosity of liquids during the phase transition and during the decompression process (hysteresis of the dependence of viscosity on pressure).

  4. Limitations On The Creation of Continuously Surfable Waves Generated By A Pressure Source Moving In A Circular Path

    NARCIS (Netherlands)

    Schmied, S.A.

    2014-01-01

    The aim of the research presented in this work was to investigate the novel idea to produce continuous breaking waves, whereby a pressure source was rotated within an annular wave pool. The concept was that the pressure source generates non-breaking waves that propagate inward to the inner ring of t

  5. Ballistic negatron battery

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, M.S.R. [Koneru Lakshmiah Univ.. Dept. of Electrical and Electronics Engineering, Green fields, Vaddeswaram (India)

    2012-07-01

    If we consider the Statistics there is drastic increase in dependence of batteries from year to year, due to necessity of power storage equipment at homes, power generating off grid and on grid Wind, PV systems, etc.. Where wind power is leading in renewable sector, there is a need to look at its development. Considering the scenario in India, most of the wind resource areas are far away from grid and the remaining areas which are near to grid are of low wind currents which is of no use connecting these equipment directly to grid. So, there is a need for a power storage utility to be integrated, such as the BNB (Ballistic Negatron Battery). In this situation a country like India need a battery which should be reliable, cheap and which can be industrialized. So this paper presents the concept of working, design, operation, adaptability of a Ballistic Negatron Battery. Unlike present batteries with low energy density, huge size, more weight, more charging time and low resistant to wear level, this Ballistic Negatron Battery comes with, 1) High energy storage capability (many multiples more than the present most advanced battery). 2) Very compact in size. 3) Almost negligible in weight compared to present batteries. 4) Charges with in very less time. 5) Never exhibits a wear level greater than zero. Seems like inconceivable but adoptable with simple physics. This paper will explains in detail the principle, model, design, construction and practical considerations considered in making this battery. (Author)

  6. Frequency interpretation of tidal peak in intracranial pressure wave.

    Science.gov (United States)

    Shahsavari, Sima; McKelvey, Tomas

    2008-01-01

    A new approach to locate different components of ICP signal for each cardiac induced ICP beat is presented. In this method an initial timing map is used to define the appropriate part of the ICP wave which should be searched for the specific component. In parallel a recently proposed method was used to decompose the ICP wave to its different frequency harmonics. This algorithm, which is based on tracking the amplitude of the harmonic components using Kalman filtering, brings both heart rate variability and cardiorespiratory interaction into account and provides good time and frequency resolution. Comparing the results of two methods for seventeen ICP records, each one hour long, it has been observed that the fundamental cardiac component has the most significant contribution in the construction of the tidal peak in ICP and therefore tracking of this harmonic could be informative of the tidal peak evolution over the time.

  7. Survivability Armor Ballistic Laboratory (SABL)

    Data.gov (United States)

    Federal Laboratory Consortium — The SABL provides independent analysis, ballistic testing, data collection, data reduction and qualification of current and advanced armors. Capabilities: The SABL...

  8. Comparative experimental study on several methods for measuring elastic wave velocities in rocks at high pressure

    Institute of Scientific and Technical Information of China (English)

    XIE; Hongsen(谢鸿森); ZHOU; Wenge; 周文戈); LIU; Yonggang; (刘永刚); GUO; Jie; (郭捷); HOU; Wei; (侯渭); ZHAO; Zhidan(赵志丹)

    2002-01-01

    To measure elastic wave velocities in rocks at high temperature and high pressure is an important way to acquire the mechanics and thermodynamics data of rocks in the earth's interior and also a substantial approach to studying the structure and composition of materials there. In recent years, a rapid progress has been made in methodology pertaining to the measurements of elastic wave velocities in rocks at high temperature and high pressure with solids as the pressure-transfer media. However, no strict comparisons have been made of the elastic wave velocity data of rocks measured at high temperature and high pressure by various laboratories. In order to compare the experimental results from various laboratories, we have conducted a comparative experimental study on three measuring methods and made a strict comparison with the results obtained by using the transmission method with fluid as the pressure-transfer medium. Our experimental results have shown that the measurements obtained by the three methods are comparable in the pressure ranges of their application. The cubic sample pulse transmission method used by Kern is applicable to measuring elastic wave velocities in crustal rocks at lower temperature and lower pressure. The prism sample pulse reflection-transmission method has some advantages in pressure range, heating temperature and measuring precision. Although the measurements obtained under relatively low pressure conditions by the prism sample pulse transmission method are relatively low in precision, the samples are large in length and their assemblage is simple. So this method is suitable to the experiments that require large quantities of samples and higher pressures. Therefore, in practical application the latter two methods are usually recommended because their measurements can be mutually corrected and supplemented.

  9. Wave reflection quantification based on pressure waveforms alone--methods, comparison, and clinical covariates.

    Science.gov (United States)

    Hametner, Bernhard; Wassertheurer, Siegfried; Kropf, Johannes; Mayer, Christopher; Holzinger, Andreas; Eber, Bernd; Weber, Thomas

    2013-03-01

    Within the last decade the quantification of pulse wave reflections mainly focused on measures of central aortic systolic pressure and its augmentation through reflections based on pulse wave analysis (PWA). A complementary approach is the wave separation analysis (WSA), which quantifies the total amount of arterial wave reflection considering both aortic pulse and flow waves. The aim of this work is the introduction and comparison of aortic blood flow models for WSA assessment. To evaluate the performance of the proposed modeling approaches (Windkessel, triangular and averaged flow), comparisons against Doppler measurements are made for 148 patients with preserved ejection fraction. Stepwise regression analysis between WSA and PWA parameters are performed to provide determinants of methodological differences. Against Doppler measurement mean difference and standard deviation of the amplitudes of the decomposed forward and backward pressure waves are comparable for Windkessel and averaged flow models. Stepwise regression analysis shows similar determinants between Doppler and Windkessel model only. The results indicate that the Windkessel method provides accurate estimates of wave reflection in subjects with preserved ejection fraction. The comparison with waveforms derived from Doppler ultrasound as well as recently proposed simple triangular and averaged flow waves showed that this approach may reduce variability and provide realistic results.

  10. Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Sacchetti, A.; /Zurich, ETH; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P.; Lupi, S.; /Rome U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.; Degiorgi, L.; /Zurich, ETH

    2009-12-14

    We investigate the pressure dependence of the optical properties of CeTe{sub 3}, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe{sub 3}.

  11. Low-pressure hydro turbines and control equipment for wave energy converters (Wave Dragon). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, H.C.; Hansen, R.

    2001-06-01

    The Wave Dragon is a 4 MW floating offshore wave energy converter of the overtopping type. Through performing tests on a scale 1:50 model of the Wave Dragon, real-time overtopping time series were provided. These allowed the development of a feasible turbine and regulation strategy for handling the varying heads and flows occurring in the reservoir. A model turbine with a runner diameter of 340 mm was designed, and tested in a conventional turbine test stand. The results revealed very high efficiencies (91.3% peak efficiency), and more importantly a very flat performance curve yielding high turbine efficiency for the complete range of heads available at the Wave Dragon. A suitable power take-off and grid connection system was developed, addressing power quality issues, as well as more practical issues of flexible cabling solutions. It was concluded that feasible solutions to the technical barriers envisioned prior to the project had been found. Also means for improving the overtopping characteristics of the device were put forward. The feasibility of the Wave Dragon at original 1st generation design was investigated and key performance figures were given as net annual power production of 5.1-3.1 GWh/year, 2,775-3,150 Euro/kW in construction costs and a power production price of 0.19-0.27 Euro/kWh. The figures includes availability losses, all losses in the power train, and losses from restricted freedom of movement for two of the scenarios, with a wave energy potential of 16 and 24 kW/m wave front respectively. Significant scope for improvement, especially from enhanced overtopping from improved design, mass production and learning effects were also identified. Through implementing the known technical improvements to the Wave Dragon design identified through the project an annual net power production of 8.9 GWh/year and a production price of 0.12 Euro/kWh is foreseen for a 24 kW/m wave potential. With additional technical improvements, mass production benefits and

  12. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    Science.gov (United States)

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  13. Photon pressure induced test mass deformation in gravitational-wave detectors

    CERN Document Server

    Hild, S; Danzmann, K; Grote, H; Hewitson, M; Hough, J; Lueck, H; Martin, I; Mossavi, K; Rainer, N; Reid, S; Smith, J R; Strain, K; Weinert, M; Willems, P; Willke, B; Winkler, W

    2007-01-01

    A widely used assumption within the gravitational-wave community has so far been that a test mass acts like a rigid body for frequencies in the detection band, i.e. for frequencies far below the first internal resonance. In this article we demonstrate that localized forces, applied for example by a photon pressure actuator, can result in a non-negligible elastic deformation of the test masses. For a photon pressure actuator setup used in the gravitational wave detector GEO600 we measured that this effect modifies the standard response function by 10% at 1 kHz and about 100% at 2.5 kHz.

  14. Models of Ballistic Propagation of Heat at Low Temperatures

    Science.gov (United States)

    Kovács, R.; Ván, P.

    2016-09-01

    Heat conduction at low temperatures shows several effects that cannot be described by the Fourier law. In this paper, the performance of various theories is compared in case of wave-like and ballistic propagation of heat pulses in NaF.

  15. The Oblique Incident Effects of Electromagnetic Wave in Atmospheric Pressure Plasma Layers

    Institute of Scientific and Technical Information of China (English)

    HE Yong; JIANG Zhonghe; HU Xiwei; LIU Minghai

    2008-01-01

    The propagating behaviours, i.e. phase shift, transmissivity, reflectivity and absorptivity, of an electromagnetic (EM) wave in a two-dimensional atmospheric pressure plasma layer are described by the numerical solutions of integral-differential Maxwell's equations through a generalized finite-difference-time-domain (FDTD) algorithm. These propagating behaviours are found to be strongly affected by five factors: two EM wave characteristics relevan.t to the oblique incident and three dimensionless factors. The two EM wave factors are the polarization mode (TM mode or TE mode) and its incident angle. The three dimensionless factors are: the ratio of the maximum electron density to the critical density n0/ncr, the ratio of the plasma layer width to the wave length d/λ, and the ratio of the collision frequency between electrons and neutrals to the incident wave frequency ve0/f.

  16. Reconstruction of stratified steady water waves from pressure readings on the ocean bed

    CERN Document Server

    Chen, Robin Ming

    2015-01-01

    Consider a two-dimensional stratified solitary wave propagating through a body of water that is bounded below by an impermeable ocean bed. In this work, we study how such a wave can be reconstructed from data consisting of the wave speed, upstream and downstream density profile, and the trace of the pressure on the bed. First, we prove that this data uniquely determines the wave, both in the (real) analytic and Sobolev regimes. Second, for waves that consist of multiple layers of constant density immiscible fluids, we provide an exact formula describing each of the interfaces in terms of the data. Finally, for continuously stratified fluids, we detail a reconstruction scheme based on approximation by layer-wise constant density flows.

  17. Acoustic Pressure Waves in Vibrating 3-D Laminated Beam-Plate Enclosures

    Directory of Open Access Journals (Sweden)

    Charles A. Osheku

    2009-01-01

    Full Text Available The effect of structural vibration on the propagation of acoustic pressure waves through a cantilevered 3-D laminated beam-plate enclosure is investigated analytically. For this problem, a set of well-posed partial differential equations governing the vibroacoustic wave interaction phenomenon are formulated and matched for the various vibrating boundary surfaces. By employing integral transforms, a closed form analytical expression is computed suitable for vibroacoustic modeling, design analysis, and general aerospace defensive applications. The closed-form expression takes the form of a kernel of polynomials for acoustic pressure waves showing the influence of linear interface pressure variation across the axes of vibrating boundary surfaces. Simulated results demonstrate how the mode shapes and the associated natural frequencies can be easily computed. It is shown in this paper that acoustic pressure waves propagation are dynamically stable through laminated enclosures with progressive decrement in interfacial pressure distribution under the influence of high excitation frequencies irrespective of whether the induced flow is subsonic, sonic , supersonic, or hypersonic. Hence, in practice, dynamic stability of hypersonic aircrafts or jet airplanes can be further enhanced by replacing their noise transmission systems with laminated enclosures.

  18. Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

    Directory of Open Access Journals (Sweden)

    Zhenxiong Wang

    2015-01-01

    Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

  19. Modeling and numerical simulation of interior ballistic processes in a 120mm mortar system

    Science.gov (United States)

    Acharya, Ragini

    by using a high-resolution Godunov-type shock-capturing approach was used where the discretization is done directly on the integral formulation of the conservation laws. A linearized approximate Riemann Solver was modified in this work for the two-phase flows to compute fully non-linear wave interactions and to directly provide upwinding properties in the scheme. An entropy fix based on Harten-Heyman method was used with van Leer flux limiter for total variation diminishing. The three dimensional effects were simulated by incorporating an unsplit multi-dimensional wave propagation method, which accounted for discontinuities traveling in both normal and oblique coordinate directions. For each component, the predicted pressure-time traces showed significant pressure wave phenomena, which closely simulated the measured pressure-time traces obtained at PSU. The pressure-time traces at the breech-end of the mortar tube were obtained at Aberdeen Test Center with 0, 2, and 4 charge increments. The 3D-MIB code was also used to simulate the effect of flash tube vent-hole pattern on the pressure-wave phenomenon in the ignition cartridge. A comparison of the pressure difference between primer-end and projectile-end locations of the original and modified ignition cartridges with each other showed that the early-phase pressure-wave phenomenon can be significantly reduced with the modified pattern. The flow property distributions predicted by the 3D-MIB for 0, 2, and 4 charge increment cases as well the projectile dynamics predictions provided adequate validation of theory by experiments.

  20. Nonlinear wave transmission and pressure on the fixed truncated breakwater using NURBS numerical wave tank

    OpenAIRE

    Abbasnia,Arash; Ghiasi,Mahmoud

    2014-01-01

    Fully nonlinear wave interaction with a fixed breakwater is investigated in a numerical wave tank (NWT). The potential theory and high-order boundary element method are used to solve the boundary value problem. Time domain simulation by a mixed Eulerian-Lagrangian (MEL) formulation and high-order boundary integral method based on non uniform rational B-spline (NURBS) formulation is employed to solve the equations. At each time step, Laplace equation is solved in Eulerian frame and fully non-l...

  1. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    Science.gov (United States)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  2. In search of objective manometric criteria for colonic high-amplitude propagated pressure waves

    NARCIS (Netherlands)

    De Schryver, AMP; Samsom, M; Smout, AJPM

    2002-01-01

    The aims of this study were to explore all characteristics of high-amplitude propagated contractions (HAPCs) that would allow them to be distinguished from nonHAPC colonic pressure waves, and to develop computer algorithms for automated HAPC detection. Colonic manometry recordings obtained from 24 h

  3. External iliac artery injury secondary to indirect pressure wave effect from gunshot wound

    OpenAIRE

    Ng, Eugene; Choong, Andrew MTL

    2016-01-01

    In patients presenting with gunshot wounds, a high clinical suspicion of injury to vasculature and viscera remote from the projectile track is paramount. We present a case of a 17 year old male who sustained a gunshot wound to his abdomen and subsequently developed a right external iliac artery contusion requiring surgery as an indirect effect of the pressure wave from the bullet.

  4. Internal wave pressure, velocity, and energy flux from density perturbations

    CERN Document Server

    Allshouse, Michael R; Morrison, Philip J; Swinney, Harry L

    2016-01-01

    Determination of energy transport is crucial for understanding the energy budget and fluid circulation in density varying fluids such as the ocean and the atmosphere. However, it is rarely possible to determine the energy flux field $\\mathbf{J} = p \\mathbf{u}$, which requires simultaneous measurements of the pressure and velocity perturbation fields, $p$ and $\\mathbf{u}$. We present a method for obtaining the instantaneous $\\mathbf{J}(x,z,t)$ from density perturbations alone: a Green's function-based calculation yields $p$, and $\\mathbf{u}$ is obtained by integrating the continuity equation and the incompressibility condition. We validate our method with results from Navier-Stokes simulations: the Green's function method is applied to the density perturbation field from the simulations, and the result for $\\mathbf{J}$ is found to agree typically to within $1\\%$ with $\\mathbf{J}$ computed directly using $p$ and $ \\mathbf{u}$ from the Navier-Stokes simulation. We also apply the Green's function method to densit...

  5. Modeling wave-induced pore pressure and effective stress in a granular seabed

    Science.gov (United States)

    Scholtès, Luc; Chareyre, Bruno; Michallet, Hervé; Catalano, Emanuele; Marzougui, Donia

    2015-01-01

    The response of a sandy seabed under wave loading is investigated on the basis of numerical modeling using a multi-scale approach. To that aim, the discrete element method is coupled to a finite volume method specially enhanced to describe compressible fluid flow. Both solid and fluid phase mechanics are upscaled from considerations established at the pore level. Model's predictions are validated against poroelasticity theory and discussed in comparison with experiments where a sediment analog is subjected to wave action in a flume. Special emphasis is put on the mechanisms leading the seabed to liquefy under wave-induced pressure variation on its surface. Liquefaction is observed in both dilative and compactive regimes. It is shown that the instability can be triggered for a well-identified range of hydraulic conditions. Particularly, the results confirm that the gas content, together with the permeability of the medium are key parameters affecting the transmission of pressure inside the soil.

  6. Acoustoelastic effects on mode waves in a fluid-filled pressurized borehole in triaxially stressed formations

    Institute of Scientific and Technical Information of China (English)

    Ping'en Li; Youquan Yin; Xianyue Su

    2006-01-01

    Based on the nonlinear theory of acoustoelasticity,considering the triaxial terrestrial stress,the fluid static pressure in the borehole and the fluid nonlinear effect jointly,the dispersion curves of the monopole Stoneley wave and dipole flexural wave propagating along the borehole axis in a homogeneous isotropic formation are investigated by using the perturbation method.The relation of the sensitivity coefficient and the velocity-stress coefficient to frequency are also analyzed.The results show that variations of the phase velocity dispersion curve are mainly affected by three sensitivity coefficients related to third-order elastic constant.The borehole stress concentration causes a split of the flexural waves and an intersection of the dispersion curves of the flexural waves polarized in directions parallel and normal to the uniaxial horizontal stress direction.The stress-induced formation anisotropy is only dependent on the horizontal deviatoric terrestrial stress and independent of the horizontal mean terrestrial stress,the superimposed stress and the fluid static pressure.The horizontal terrestrial stress ratio ranging from 0 to 1 reduces the stress-induced formation anisotropy.This makes the intersection of flexural wave dispersion curves not distinguishable.The effect of the fluid nonlinearity on the dispersion curve of the mode wave is small and can be ignored.

  7. Experimental Study on a Standing Wave Thermoacoustic Prime Mover with Air Working Gas at Various Pressures

    Science.gov (United States)

    Setiawan, Ikhsan; Achmadin, Wahyu N.; Murti, Prastowo; Nohtomi, Makoto

    2016-04-01

    Thermoacoustic prime mover is an energy conversion device which converts thermal energy into acoustic work (sound wave). The advantages of this machine are that it can work with air as the working gas and does not produce any exhaust gases, so that it is environmentally friendly. This paper describes an experimental study on a standing wave thermoacoustic prime mover with air as the working gas at various pressures from 0.05 MPa to 0.6 MPa. We found that 0.2 MPa is the optimum pressure which gives the lowest onset temperature difference of 355 °C. This pressure value would be more preferable in harnessing low grade heat sources to power the thermoacoustic prime mover. In addition, we find that the lowest onset temperature difference is obtained when rh /δ k ratio is 2.85, where r h is the hydraulic radius of the stack and δ k is the thermal penetration depth of the gas. Moreover, the pressure amplitude of the sound wave is significantly getting larger from 2.0 kPa to 9.0 kPa as the charged pressure increases from 0.05 MPa up to 0.6 MPa.

  8. Experimental model for civilian ballistic brain injury biomechanics quantification.

    Science.gov (United States)

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A; Guan, Yabo; Gennarelli, Thomas A

    2007-01-01

    Biomechanical quantification of projectile penetration using experimental head models can enhance the understanding of civilian ballistic brain injury and advance treatment. Two of the most commonly used handgun projectiles (25-cal, 275 m/s and 9 mm, 395 m/s) were discharged to spherical head models with gelatin and Sylgard simulants. Four ballistic pressure transducers recorded temporal pressure distributions at 308kHz, and temporal cavity dynamics were captured at 20,000 frames/second (fps) using high-speed digital video images. Pressures ranged from 644.6 to -92.8 kPa. Entry pressures in gelatin models were higher than exit pressures, whereas in Sylgard models entry pressures were lower or equivalent to exit pressures. Gelatin responded with brittle-type failure, while Sylgard demonstrated a ductile pattern through formation of micro-bubbles along projectile path. Temporary cavities in Sylgard models were 1.5-2x larger than gelatin models. Pressures in Sylgard models were more sensitive to projectile velocity and diameter increase, indicating Sylgard was more rate sensitive than gelatin. Based on failure patterns and brain tissue rate-sensitive characteristics, Sylgard was found to be an appropriate simulant. Compared with spherical projectile data, full-metal jacket (FMJ) projectiles produced different temporary cavity and pressures, demonstrating shape effects. Models using Sylgard gel and FMJ projectiles are appropriate to enhance understanding and mechanisms of ballistic brain injury.

  9. Theory of azimuthally small-scale hydromagnetic waves in the axisymmetric magnetosphere with finite plasma pressure

    Directory of Open Access Journals (Sweden)

    D. Y. Klimushkin

    Full Text Available The structure of monochromatic MHD-waves with large azimuthal wave number m≫1 in a two-dimensional model of the magnetosphere has been investigated. A joint action of the field line curvature, finite plasma pressure, and transversal equilibrium current leads to the phenomenon that waves, standing along the field lines, are travelling across the magnetic shells. The wave propagation region, the transparency region, is bounded by the poloidal magnetic surface on one side and by the resonance surface on the other. In their meaning these surfaces correspond to the usual and singular turning points in the WKB-approximation, respectively. The wave is excited near the poloidal surface and propagates toward the resonance surface where it is totally absorbed due to the ionospheric dissipation. There are two transparency regions in a finite-beta magnetosphere, one of them corresponds to the Alfvén mode and the other to the slow magnetosound mode.

    Key words. Magnetosphere · Azimuthally small-scale waves · MHD waves

  10. Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse

    Science.gov (United States)

    Shen, X. C.; Shi, Q. Q.; Zong, Q.-G.; Tian, A. M.; Nowada, M.; Sun, W. J.; Zhao, H. Y.; Hudson, M. K.; Wang, H. Z.; Fu, S. Y.; Pu, Z. Y.

    2017-02-01

    Ultralow frequency (ULF) waves play an important role in the transport of the solar wind energy to the magnetosphere. In this paper, we present a ULF wave event in the dayside magnetosphere which shows a sudden decrease in frequency from 3.1 to 2.3 mHz around 0756 UT on 11 January 2010, when a solar wind dynamic pressure drop (from ˜5 to ˜2 nPa) was observed simultaneously. The wave exits globally. The phase differences between electric and magnetic fields indicate that the compressional mode wave is standing before and after the wave frequency decrease. This result suggests that the ULF wave should be associated with a cavity mode and the frequency decrease might be induced by the change of the cavity size. A theoretical calculation was made to estimate the cavity mode frequency. The calculated wave frequency before/after the negative impulse is 3.8/2.6 mHz, which is consistent with the observations.

  11. Water Waves from General, Time-Dependent Surface Pressure Distribution in the Presence of a Shear Current

    CERN Document Server

    Li, Yan

    2015-01-01

    We obtain a general solution for the water waves resulting from a general, time-dependent surface pressure distribution, in the presence of a shear current of uniform vorticity beneath the surface, in three dimensions. Linearized governing equations and boundary conditions including the effects of gravity, a distributed external pressure disturbance, and constant finite depth, are solved analytically, and particular attention is paid to classic initial value problems: an initial pressure impulse and a steady pressure distribution which appears suddenly. In the present paper, good agreement with previous results is demonstrated. We subsequently show both analytically and numerically how transient waves from a suddenly appearing steady pressure distribution vanis for large times, and steady ship waves remain. The transient contribution to wave resistance was derived. The results show that a shear current has significant impact on the transient wave motions, resulting in asymmetry between upstream and downstream...

  12. Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo [Tokyo Institute of Technology (Japan)

    1995-09-01

    In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that there exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.

  13. Gunshot wounds: A review of ballistics related to penetrating trauma

    Directory of Open Access Journals (Sweden)

    Panagiotis K. Stefanopoulos

    2014-01-01

    Full Text Available Civilian gunshot injuries from handgun and rifle ammunition vary in severity depending on the anatomic location involved and the different effects from the ballistic properties of the penetrating projectiles. Ballistic factors such as the impact velocity and energy should not be considered in isolation, as their specific effects are determined by the interaction between the projectile and tissues. Increased tissue damage can result from tumbling of non-deforming rifle bullets and deformation of expanding bullets. Both of these mechanisms increase substantially the energy transfer to the wound and its diameter, also producing a pulsating temporary cavity associated with pressure changes within tissue.

  14. Internal Ballistics of High Velocity Special Purpose Guns

    Directory of Open Access Journals (Sweden)

    V. K. Gupta

    1976-07-01

    Full Text Available More and more conventional guns are being utilized as special purpose guns to achieve very high velocity by using unconventionally high C/W ratios. The existing methods of internal ballistics give satisfactory results only for low (less than one C/W ratios. In the present paper the basic internal ballistic equations have been modified to cater for non-linear rate of burning, cubical form function and a realistic pressure gradient between breech face and the projectile base. The equations have been numerically solved. The results for low and high C/W ratios have been compared with those obtained by using conventional methods.

  15. Pressure Wave Measurements from Thermal Cook-off of an HMX Based Explosive

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2001-05-09

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  16. Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, F; Forbes, J W; Tarver, C M; Urtiew, P A; Greenwood, D W; Vandersall, K S

    2001-05-31

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  17. Pressure wave measurements from thermal cook-off of an HMX based high explosive

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2000-10-10

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  18. Superconductivity of Cu/CuOx interface formed by shock-wave pressure

    Science.gov (United States)

    Shakhray, D. V.; Avdonin, V. V.; Palnichenko, A. V.

    2016-11-01

    A mixture of powdered Cu and CuO has been subjected to shock-wave pressure of 350 kbar with following quenching of the vacuum-encapsulated product to 77 K. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 19 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the DC magnetization measurements infers that the superconductivity arises within the granular interfacial layer formed between metallic Cu and its oxides due to the shock-wave treatment.

  19. Ballistic Missile Defense System (BMDS)

    Science.gov (United States)

    2015-12-01

    Estimate RDT&E - Research , Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be Determined TY - Then...all ranges and in all phases of flight. Following guidance from the President, the Secretary of Defense approved the Ballistic Missile Defense (BMD...based Midcourse Defense (GMD) system to enhance our capability against Intercontinental Ballistic Missiles. We are currently sustaining 30

  20. Radial energy transport by magnetospheric ULF waves: Effects of magnetic curvature and plasma pressure

    Science.gov (United States)

    Kouznetsov, Igor; Lotko, William

    1995-01-01

    The 'radial' transport of energy by internal ULF waves, stimulated by dayside magnetospheric boundary oscillations, is analyzed in the framework of one-fluid magnetohydrodynamics. (the term radial is used here to denote the direction orthogonal to geomagnetic flux surfaces.) The model for the inhomogeneous magnetospheric plasma and background magnetic field is axisymmetric and includes radial and parallel variations in the magnetic field, magnetic curvature, plasma density, and low but finite plasma pressure. The radial mode structure of the coupled fast and intermediate MHD waves is determined by numerical solution of the inhomogeneous wave equation; the parallel mode structure is characterized by a Wentzel-Kramer-Brillouin (WKB) approximation. Ionospheric dissipation is modeled by allowing the parallel wave number to be complex. For boudnary oscillations with frequencies in the range from 10 to 48 mHz, and using a dipole model for the background magnetic field, the combined effects of magnetic curvature and finite plasma pressure are shown to (1) enhance the amplitude of field line resonances by as much as a factor of 2 relative to values obtained in a cold plasma or box-model approximation for the dayside magnetosphere; (2) increase the energy flux delivered to a given resonance by a factor of 2-4; and (3) broaden the spectral width of the resonance by a factor of 2-3. The effects are attributed to the existence of an 'Alfven buoyancy oscillation,' which approaches the usual shear mode Alfven wave at resonance, but unlike the shear Alfven mode, it is dispersive at short perpendicular wavelengths. The form of dispersion is analogous to that of an internal atmospheric gravity wave, with the magnetic tension of the curved background field providing the restoring force and allowing radial propagation of the mode. For nominal dayside parameters, the propagation band of the Alfven buoyancy wave occurs between the location of its (field line) resonance and that of the

  1. Arterial pulse pressure amplification described by means of a nonlinear wave model: characterization of human aging

    Science.gov (United States)

    Alfonso, M.; Cymberknop, L.; Armentano, R.; Pessana, F.; Wray, S.; Legnani, W.

    2016-04-01

    The representation of blood pressure pulse as a combination of solitons captures many of the phenomena observed during its propagation along the systemic circulation. The aim of this work is to analyze the applicability of a compartmental model for propagation regarding the pressure pulse amplification associated with arterial aging. The model was applied to blood pressure waveforms that were synthesized using solitons, and then validated by waveforms obtained from individuals from differentiated age groups. Morphological changes were verified in the blood pressure waveform as a consequence of the aging process (i.e. due to the increase in arterial stiffness). These changes are the result of both a nonlinear interaction and the phenomena present in the propagation of nonlinear mechanic waves.

  2. Central blood pressure assessment using 24-hour brachial pulse wave analysis

    Directory of Open Access Journals (Sweden)

    Muiesan ML

    2014-10-01

    Full Text Available Maria Lorenza Muiesan, Massimo Salvetti, Fabio Bertacchini, Claudia Agabiti-Rosei, Giulia Maruelli, Efrem Colonetti, Anna Paini Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy Abstract: This review describes the use of central blood pressure (BP measurements during ambulatory monitoring, using noninvasive devices. The principles of measuring central BP by applanation tonometry and by oscillometry are reported, and information on device validation studies is described. The pathophysiological basis for the differences between brachial and aortic pressure is discussed. The currently available methods for central aortic pressure measurement are relatively accurate, and their use has important clinical implications, such as improving diagnostic and prognostic stratification of hypertension and providing a more accurate assessment of the effect of treatment on BP. Keywords: aortic blood pressure measurements, ambulatory monitoring, pulse wave analysis

  3. Cavitation inception by the backscattering of pressure waves from a bubble interface

    Science.gov (United States)

    Takahira, Hiroyuki; Ogasawara, Toshiyuki; Mori, Naoto; Tanaka, Moe

    2015-10-01

    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t0 to a characteristic time of wave propagation tS, η = t0/ts, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  4. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    Science.gov (United States)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-09-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  5. Numerical simulation of pressure waves in the cochlea induced by a microwave pulse.

    Science.gov (United States)

    Yitzhak, Nir M; Ruppin, Raphael; Hareuveny, Ronen

    2014-10-01

    The pressure waves developing at the cochlea by the irradiation of the body with a plane wave microwave pulse are obtained by numerical simulation, employing a two-step finite-difference time-domain (FDTD) algorithm. First, the specific absorption rate (SAR) distribution is obtained by solving the Maxwell equations on a FDTD grid. Second, the temperature rise due to this SAR distribution is used to formulate the thermoelastic equations of motion, which are discretized and solved by the FDTD method. The calculations are performed for anatomically based full body human models, as well as for a head model. The dependence of the pressure amplitude at the cochlea on the frequency, the direction of propagation, and the polarization of the incident electromagnetic radiation, as well as on the pulse width, was investigated.

  6. New experimental capabilities and theoretical insights of high pressure compression waves

    Energy Technology Data Exchange (ETDEWEB)

    Orlikowski, D; Nguyen, J; Patterson, J R; Minich, R; Martin, L P; Holmes, N

    2007-07-20

    Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition of water plus its associated phase fraction history. We also introduce the Korteweg-deVries-Burgers equation as a means to understand the evolution these RWC waves that propagate through the thickness of the subject material. This equation has the necessary competition between non-linear, dispersion, and dissipation processes, which is shown through observed structures that are manifested in the experimental particle velocity histories. Such methodology points towards a possible quantifiable dissipation, through which RWC experiments may be analyzed.

  7. Nonlinear acoustics in a dispersive continuum: Random waves, radiation pressure, and quantum noise

    Science.gov (United States)

    Cabot, M. A.

    The nonlinear interaction of sound with sound is studied using dispersive hydrodynamics which derived from a variational principle and the assumption that the internal energy density depends on gradients of the mass density. The attenuation of sound due to nonlinear interaction with a background is calculated and is shown to be sensitive to both the nature of the dispersion and decay bandwidths. The theoretical results are compared to those of low temperature helium experiments. A kinetic equation which described the nonlinear self-inter action of a background is derived. When a Deybe-type cutoff is imposed, a white noise distribution is shown to be a stationary distribution of the kinetic equation. The attenuation and spectrum of decay of a sound wave due to nonlinear interaction with zero point motion is calculated. In one dimension, the dispersive hydrodynamic equations are used to calculate the Langevin and Rayleigh radiation pressures of wave packets and solitary waves.

  8. Low-frequency pressure wave propagation in liquid-filled, flexible tubes. (A)

    DEFF Research Database (Denmark)

    Bjørnø, Leif; Bjelland, C.

    1992-01-01

    A model has been developed for propagation of low-frequency pressure waves in viscoelastic tubes with distensibility of greater importance than compressibility of the liquid. The dispersion and attenuation are shown to be strongly dependent on the viscoelastic properties of the tube wall....... The complex, frequency-dependent moduli of relevant tube materials have been measured in a series of experiments using three different experimental procedures, and the data obtained are compared. The three procedures were: (1) ultrasonic wave propagation, (2) transversal resonance in bar samples, and (3......) moduli determined by stress wave transfer function measurements in simple extension experiments. The moduli are used in the model to produce realistic dispersion relations and frequency dependent attenuation. Signal transfer functions between positions in the liquid-filled tube can be synthesized from...

  9. The vibration of a box-type structure. II - Response to a travelling pressure wave.

    Science.gov (United States)

    Popplewell, N.

    1971-01-01

    A finite element method is formulated for determining the transient response of a box-type structure to a traveling, arbitrarily shaped pressure wave. The method is illustrated by considering an example of practical concern - the sonic boom. The acceleration-time histories of a closed box are compared with those obtained experimentally from a simulated boom. Satisfactory agreement is obtained with only four rectangular elements per individual face and a simplified loading of the box.

  10. Interactions of Delta Shock Waves for Zero-Pressure Gas Dynamics with Energy Conservation Law

    Directory of Open Access Journals (Sweden)

    Wei Cai

    2016-01-01

    Full Text Available We study the interactions of delta shock waves and vacuum states for the system of conservation laws of mass, momentum, and energy in zero-pressure gas dynamics. The Riemann problems with initial data of three piecewise constant states are solved case by case, and four different configurations of Riemann solutions are constructed. Furthermore, the numerical simulations completely coinciding with theoretical analysis are shown.

  11. External iliac artery injury secondary to indirect pressure wave effect from gunshot wound

    Institute of Scientific and Technical Information of China (English)

    Eugene Ng; Andrew MTL.Choong

    2016-01-01

    In patients presenting with gunshot wounds,a high clinical suspicion of injury to vasculature and viscera remote from the projectile track is paramount.We present a case of a 17 year old male who sustained a gunshot wound to his abdomen and subsequently developed a right external iliac artery contusion requiring surgery as an indirect effect of the pressure wave from the bullet.

  12. In situ measurements of impact-induced pressure waves in sandstone targets

    Science.gov (United States)

    Hoerth, Tobias; Schäfer, Frank; Nau, Siegfried; Kuder, Jürgen; Poelchau, Michael H.; Thoma, Klaus; Kenkmann, Thomas

    2014-10-01

    In the present study we introduce an innovative method for the measurement of impact-induced pressure waves within geological materials. Impact experiments on dry and water-saturated sandstone targets were conducted at a velocity of 4600 m/s using 12 mm steel projectiles to investigate amplitudes, decay behavior, and speed of the waves propagating through the target material. For this purpose a special kind of piezoresistive sensor capable of recording transient stress pulses within solid brittle materials was developed and calibrated using a Split-Hopkinson pressure bar. Experimental impact parameters (projectile size and speed) were kept constant and yielded reproducible signal curves in terms of rise time and peak amplitudes. Pressure amplitudes decreased by 3 orders of magnitude within the first 250 mm (i.e., 42 projectile radii). The attenuation for water-saturated sandstone is higher compared to dry sandstone which is attributed to dissipation effects caused by relative motion between bulk material and interstitial water. The proportion of the impact energy radiated as seismic energy (seismic efficiency) is in the order of 10-3. The present study shows the feasibility of real-time measurements of waves caused by hypervelocity impacts on geological materials. Experiments of this kind lead to a better understanding of the processes in the crater subsurface during a hypervelocity impact.

  13. Calculation Analysis of Pressure Wave Velocity in Gas and Drilling Mud Two-Phase Fluid in Annulus during Drilling Operations

    Directory of Open Access Journals (Sweden)

    Yuanhua Lin

    2013-01-01

    Full Text Available Investigation of propagation characteristics of a pressure wave is of great significance to the solution of the transient pressure problem caused by unsteady operations during management pressure drilling operations. With consideration of the important factors such as virtual mass force, drag force, angular frequency, gas influx rate, pressure, temperature, and well depth, a united wave velocity model has been proposed based on pressure gradient equations in drilling operations, gas-liquid two-fluid model, the gas-drilling mud equations of state, and small perturbation theory. Solved by adopting the Runge-Kutta method, calculation results indicate that the wave velocity and void fraction have different values with respect to well depth. In the annulus, the drop of pressure causes an increase in void fraction along the flow direction. The void fraction increases first slightly and then sharply; correspondingly the wave velocity first gradually decreases and then slightly increases. In general, the wave velocity tends to increase with the increase in back pressure and the decrease of gas influx rate and angular frequency, significantly in low range. Taking the virtual mass force into account, the dispersion characteristic of the pressure wave weakens obviously, especially at the position close to the wellhead.

  14. Analytical solutions for dynamic pressures of coupling fluid-solid-porous medium due to P wave incidence

    Institute of Scientific and Technical Information of China (English)

    王进廷; 张楚汉; 金峰

    2004-01-01

    Wave reflection and refraction in layered media is a topic closely related to seismology, acoustics, geophysics and earthquake engineering. Analytical solutions for wave reflection and refraction coefficients in multi-layered media subjected to P wave incidence from the elastic half-space are derived in terms of displacement potentials. The system is composed of ideal fluid, porous medium, and underlying elastic solid. By numerical examples, the effects of porous medium and the incident wave angle on the dynamic pressures of ideal fluid are analyzed. The results show that the existence of the porous medium, especially in the partially saturated case, may significantly affect the dynamic pressures of the overlying fluid.

  15. Optimizing Ballistic Imaging Operations.

    Science.gov (United States)

    Wang, Can; Beggs-Cassin, Mardy; Wein, Lawrence M

    2017-04-03

    Ballistic imaging systems can help solve crimes by comparing images of cartridge cases, which are recovered from a crime scene or test-fired from a gun, to a database of images obtained from past crime scenes. Many U.S. municipalities lack the resources to process all of their cartridge cases. Using data from Stockton, CA, we analyze two problems: how to allocate limited capacity to maximize the number of cartridge cases that generate at least one hit, and how to prioritize the cartridge cases that are processed to maximize the usefulness (i.e., obtained before the corresponding criminal case is closed) of hits. The number of hits can be significantly increased by prioritizing crime scene evidence over test-fires, and by ranking calibers by their hit probability and processing only the higher ranking calibers. We also estimate that last-come first-served increases the proportion of hits that are useful by only 0.05 relative to first-come first-served.

  16. Numerical Estimation of Incident Wave Parameters Based on the Air Pressure Measurements in Pico OWC Plant

    Energy Technology Data Exchange (ETDEWEB)

    Le Crom, I.; Brito-Melo, A.; Newman, F. Sarmento, A. [Wave Energy Centre, Av. Manuel da Maia, 36, r/c D., Lisbon (Portugal)

    2009-07-01

    The present study aims at assessing the key spectral parameters of the incident wave on a fixed oscillating water column (OWC) device, based on the air pressure measurements inside the chamber and on the numerical hydrodynamic coefficients of the device. The methodology is based on the equation of continuity of the air in the time-domain and linear decomposition of the air flow in the usual terms of radiation and diffraction flows. By applying the Fast Fourier Transform, the time-domain equation is transposed to the respective frequency-domain equation. This methodology was applied to the 400 kW OWC power plant, on the Island of Pico, Azores, which has been monitored since 2005 by the Wave Energy Centre. The numerical hydrodynamic coefficients obtained by the 3D radiation-diffraction boundary element code, AQUADYN-OWC, were used in this study. No measurements of the incident wave in front of the plant are available; therefore the results obtained for a set of records are compared with forecast estimations for the site of Pico plant provided by INETI and also with the measurements of two directional wave rider buoys offshore Pico and Terceira islands. These data are provided by the Centre of Climate, Meteorology and Global Changes and propagated via the SWAN spectral wave model to the zone of interest. Final objective is to improve the control of the Pico plant by assessing its performance for a range of sea states.

  17. Two-dimensional vertical moisture-pressure dynamics above groundwater waves: Sand flume experiments and modelling

    Science.gov (United States)

    Shoushtari, Seyed Mohammad Hossein Jazayeri; Cartwright, Nick; Perrochet, Pierre; Nielsen, Peter

    2017-01-01

    This paper presents a new laboratory dataset on the moisture-pressure relationship above a dispersive groundwater wave in a two-dimensional vertical unconfined sand flume aquifer driven by simple harmonic forcing. A total of five experiments were conducted in which all experimental parameters were kept constant except for the oscillation period, which ranged from 268 s to 2449 s between tests. Moisture content and suction head sensor pairings were co-located at two locations in the unsaturated zone both approximately 0.2 m above the mean watertable elevation and respectively 0.3 m and 0.75 m from the driving head boundary. For all oscillation periods except for the shortest (T = 268s), the formation of a hysteretic moisture-pressure scanning loop was observed. Consistent with the decay of the saturated zone groundwater wave, the size of the observed moisture-pressure scanning loops decayed with increasing distance landward and the decay rate is larger for the shorter oscillation periods. At the shortest period (T = 268s), the observed moisture-pressure relationship was observed to be non-hysteretic but with a capillary capacity that differs from that of the static equilibrium wetting and drying curves. This finding is consistent with observations from existing one-dimensional vertical sand column experiments. The relative damping of the moisture content with distance landward is higher than that for the suction head consistent with the fact that transmission of pressure through a porous medium occurs more readily than mass transfer. This is further supported by the fact that observed phase lags for the unsaturated zone variables (i.e. suction head and moisture content) relative to the driving head are greater than the saturated zone variables (i.e. piezometric head). Harmonic analysis of the data reveals no observable generation of higher harmonics in either moisture or pressure despite the strongly non-linear relationship between the two. In addition, a phase lag

  18. Laboratory measurement of longitudinal wave velocity of artificial gas hydrate under different temperatures and pressures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The longitudinal wave velocity and attenuation measurements of artificial gas hy- drate samples at a low temperature are reported. And the temperature and pressure dependence of longitudinal wave velocity is also investigated. In order to under- stand the acoustic properties of gas hydrate, the pure ice, the pure tetrahydrofuran (THF), the pure gas hydrate samples and sand sediment containing gas hydrate are measured at a low temperature between 0℃ and –15℃. For the pure ice, the pure THF and the pure gas hydrate samples, whose density is 898 kg/m3, 895 kg/m3 and 475 kg/m3, the velocity of longitudinal wave is respectively 3574 m/s, 3428 m/s and 2439 m/s. For synthesized and compacted samples, the velocity of synthesized samples is lower than that of compacted samples. The velocities increase when the densities of the samples increase, while the attenuation decreases. Under the con- dition of low temperature, the results show that the velocity is slightly affected by the temperature. The results also show that wave velocities increase with the in- crease of piston pressures. For example, the velocity of one sample increases from 3049 up to 3337 m/s and the other increases from 2315 up to 2995 m/s. But wave velocity decreases from 3800 to 3546 m/s when the temperature increases from –15℃ to 5℃ and changes significantly close to the melting point. Formation con- ditions of the two samples are the same but with different conversion ratios of wa- ter. The results of the experiment are important for exploration of the gas hydrate resources and development of acoustic techniques.

  19. Water-hammer pressure waves interaction at cross-section changes in series in viscoelastic pipes

    Science.gov (United States)

    Meniconi, S.; Brunone, B.; Ferrante, M.

    2012-08-01

    In view of scarcity of both experimental data and numerical models concerning transient behavior of cross-section area changes in pressurized liquid flow, the paper presents laboratory data and numerical simulation of the interaction of a surge wave with a partial blockage by a valve, a single pipe contraction or expansion and a series of pipe contraction/expansion in close proximity.With regard to a single change of cross-section area, laboratory data point out the completely different behavior with respect to one of the partially closed in-line valves with the same area ratio. In fact, for the former the pressure wave interaction is not regulated by the steady-state local head loss. With regard to partial blockages, transient tests have shown that the smaller the length, the more intense the overlapping of pressure waves due to the expansion and contraction in series.Numerically, the need for taking into account both the viscoelasticity and unsteady friction is demonstrated, since the classical water-hammer theory does not simulate the relevant damping of pressure peaks and gives rise to a time shifting between numerical and laboratory data. The transient behavior of a single local head loss has been checked by considering tests carried out in a system with a partially closed in-line valve. As a result, the reliability of the quasi steady-state approach for local head loss simulation has been demonstrated in viscoelastic pipes. The model parameters obtained on the basis of transients carried out in single pipe systems have then been used to simulate transients in the more complex pipe systems. These numerical experiments show the great importance of the length of the small-bore pipe with respect to one of the large-bore pipes. Precisely, until a gradually flow establishes in the small-bore pipe, the smaller such a length, the better the quality of the numerical simulation.

  20. Modeling Of Ballistic Missile Dynamics

    Directory of Open Access Journals (Sweden)

    Salih Mahmoud Attiya

    2013-05-01

    Full Text Available Aerodynamic modeling of ballistic missile in pitch plane is performed and the open-loop transfer function related to the jet deflector angle as input and pitch rate, normal acceleration as output has been derived with certain acceptable assumptions. For typical values of ballistic missile parameters such as mass, velocity, altitude, moment of inertia, thrust, moment and lift coefficient show that, the step time response and frequency response of the missile is unstable. The steady state gain, damping ratio and undraped natural frequency depend on the missile parameters. To stabilize the missile a lead compensator must be added to the forward loop.

  1. Modeling and simulations on the propagation characteristics of electromagnetic waves in sub-atmospheric pressure plasma slab

    Science.gov (United States)

    Wang, Z. B.; Nie, Q. Y.; Li, B. W.; Kong, F. R.

    2017-01-01

    Sub-atmospheric pressure plasma slabs exhibit the feature of relatively high plasma number density and high collisional frequency between electrons and neutral gases, as well as similar thickness to the electromagnetic (EM) wavelength in communication bands. The propagation characteristics of EM waves in sub-atmospheric pressure plasma slabs are attracting much attention of the researchers due to their applications in the plasma antenna, the blackout effect during reentry, wave energy injection in the plasma, etc. In this paper, a numerical model with a one-dimensional assumption has been established and therefore, it is used for the investigations of the propagation characteristics of the EM waves in plasma slabs. In this model, the EM waves propagating in both sub-wavelength plasma slabs and plasmas with thicker slabs can be studied simultaneously, which is superior to the model with geometrical optics approximation. The influence of EM wave frequencies and collisional frequencies on the amplitude of the transmitted EM waves is discussed in typical plasma profiles. The results will be significant for deep understanding of the propagation behaviors of the EM waves in sub-atmospheric pressure nonuniform plasma slabs, as well as the applications of the interactions between EM waves and the sub-atmospheric pressure plasmas.

  2. Cavitation inception by the backscattering of pressure waves from a bubble interface

    Energy Technology Data Exchange (ETDEWEB)

    Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp; Tanaka, Moe [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531 (Japan)

    2015-10-28

    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  3. First hints of pressure waves in a helical extragalactic jet: S5~0836+710

    CERN Document Server

    Perucho, Manel

    2013-01-01

    One of the open questions in extragalactic jet Astrophysics is related to the nature of the observed radio jet, namely whether it traces a pattern or the flow structure itself. In this paper I summarize the evidence collected for the presence of waves in extragalactic jets. The evidence points towards the peak of emission in helical jets corresponding to pressure-maxima of a wave that is generated within the core region and propagates downstream. Making use of a number of very long baseline interferometry (VLBI) observations of the radio jet in the quasar S5~0836+710 at different frequencies and epochs, Perucho et al. (2012) were able to observe wave-like behavior within the observed radio-jet. The ridge-line of the emission in the jet coincides within the errors at all frequencies. Moreover, small differences between epochs at 15 GHz reveal wave-like motion of the ridge-line transversal to the jet propagation axis. The authors conclude that the helicity is a real, physical structure. I report here on those r...

  4. All-Optical Detection of Acoustic Pressure Waves with applications in Photo-Acoustic Spectroscopy

    CERN Document Server

    Westergaard, Philip G

    2016-01-01

    An all-optical detection method for the detection of acoustic pressure waves is demonstrated. The detection system is based on a stripped (bare) single-mode fiber. The fiber vibrates as a standard cantilever and the optical output from the fiber is imaged to a displacement-sensitive optical detector. The absence of a conventional microphone makes the demonstrated system less susceptible to the effects that a hazardous environment might have on the sensor. The sensor is also useful for measurements in high temperature (above $200^{\\circ}$C) environments where conventional microphones will not operate. The proof-of-concept of the all-optical detection method is demonstrated by detecting sound waves generated by the photo-acoustic effect of NO$_2$ excited by a 455 nm LED, where a detection sensitivity of approximately 50 ppm was achieved.

  5. Droplet actuation by surface acoustic waves: an interplay between acoustic streaming and radiation pressure

    Science.gov (United States)

    Brunet, Philippe; Baudoin, Michael; Matar, Olivier Bou; Zoueshtiagh, Farzam

    2010-11-01

    Surface acoustic waves (SAW) are known to be a versatile technique for the actuation of sessile drops. Droplet displacement, internal mixing or drop splitting, are amongst the elementary operations that SAW can achieve, which are useful on lab-on-chip microfluidics benches. On the purpose to understand the underlying physical mechanisms involved during these operations, we study experimentally the droplet dynamics varying different physical parameters. Here in particular, the influence of liquid viscosity and acoustic frequency is investigated: it is indeed predicted that both quantities should play a role in the acoustic-hydrodynamic coupling involved in the dynamics. The key point is to compare the relative magnitude of the attenuation length, i.e. the scale within which the acoustic wave decays in the fluid, and the size of the drop. This relative magnitude governs the relative importance of acoustic streaming and acoustic radiation pressure, which are both involved in the droplet dynamics.

  6. Optimal pressure-sensitive cuts for surface acoustic waves on langasite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The crystal langasite manifests its unique advantages and potentials for high temperature applications due to a high electromechanical coupling coefficient, temperature compensated orientations for surface acoustic wave (SAW), and temperature stability. In order to analyze the pressure-induced frequency shift in SAW resonator type sensors at high temperature, this paper presents the electroelastic wave equations employing the effective material constants for small vibrations superimposed on biases originated from homogeneous temperature and external pressure fields in the Lagrangian description. Incorporated with the first-order perturbation integration, a model including both the mechanical and electrical perturbation items originating from thermal biases and small pressure fields is proposed. This universal model is suitable for substrate with high piezoelectricity and can be applied at either room temperature or high temperature circumstance. The criteria of optimal cuts for SAW pressure sensitivity, I.e., high electromechanical coupling coefficient and low temperature coefficient of delay, are proposed. A thorough investigation in trebly rotated cuts has shown that optimal pressure sensitive crystallographic areas can be obtained. The areas suitable for pressure sensors at room temperature are defined with Euler anglesThe areas suitable for pressure sensors at high temperature are defined with Euler anglesΩ1: φ= 0°―0.6°,θ= 144.4°―145.8°, ψ= 23.2°―24.1°,Ω2: φ=59.4°―61°,θ= 34.2°―36.2°, ψ= 24.1°―22.3°,Ω3: φ=119°―120°,θ = 143.8°―145.5°, ψ= 22.3°―23.5°.The areas suitable for pressure sensors at high temperature are defined with Euler anglesI:φ= 8°―30°,θ= 24°―36°,ψ= 4°―25°,II:φ = 30°―55°,θ= 144°―158°,ψ= 4°―28°.A set of experiments employing LGS (0, 150°, 22°) and (0, 90°, 0) has been performed to check the validity of the proposed calculation. The experimental relative sensitivity is

  7. Studies on an improved indigenous pressure wave generator and its testing with a pulse tube cooler

    Science.gov (United States)

    Jacob, S.; Karunanithi, R.; Narsimham, G. S. V. L.; Kranthi, J. Kumar; Damu, C.; Praveen, T.; Samir, M.; Mallappa, A.

    2014-01-01

    Earlier version of an indigenously developed Pressure Wave Generator (PWG) could not develop the necessary pressure ratio to satisfactorily operate a pulse tube cooler, largely due to high blow by losses in the piston cylinder seal gap and due to a few design deficiencies. Effect of different parameters like seal gap, piston diameter, piston stroke, moving mass and the piston back volume on the performance is studied analytically. Modifications were done to the PWG based on analysis and the performance is experimentally measured. A significant improvement in PWG performance is seen as a result of the modifications. The improved PWG is tested with the same pulse tube cooler but with different inertance tube configurations. A no load temperature of 130 K is achieved with an inertance tube configuration designed using Sage software. The delivered PV power is estimated to be 28.4 W which can produce a refrigeration of about 1 W at 80 K.

  8. BALLISTIC RESISTANT ARTICLES COMPRISING TAPES

    NARCIS (Netherlands)

    VAN DER EEM, JORIS; HARINGS, JULES; JANSE, GERARDUS; TJADEN, HENDRIK

    2015-01-01

    The invention pertains to a ballistic-resistant moulded article comprising a compressed stack of sheets comprising reinforcing tapes having a tensile strength of at least 1.0 GPa, a tensile modulus of at least 40 GPa, and a tensile energy-to-break of at least 15 J/g, the direction of the tapes withi

  9. Ballistics examination of air rifle.

    Science.gov (United States)

    Bogiel, G

    2014-01-01

    The aim of this paper is to determine the velocity, energy, maximum range and distance at which pellets fired from an air rifle of kinetic energy below 17 J can pose a threat to unprotected human skin. Doppler radar equipment and exterior ballistics software were used in this examination.

  10. Ballistics examination of air rifle

    Directory of Open Access Journals (Sweden)

    Grzegorz Bogiel

    2014-08-01

    Full Text Available The aim of this paper is to determine the velocity, energy, maximum range and distance at which pellets fired from an air rifle of kinetic energy below 17 J can pose a threat to unprotected human skin. Doppler radar equipment and exterior ballistics software were used in this examination.

  11. Ballistics examination of air rifle

    OpenAIRE

    2014-01-01

    The aim of this paper is to determine the velocity, energy, maximum range and distance at which pellets fired from an air rifle of kinetic energy below 17 J can pose a threat to unprotected human skin. Doppler radar equipment and exterior ballistics software were used in this examination.

  12. Changes in Central Aortic Pressure Levels, Wave Components and Determinants Associated with High Peripheral Blood Pressure States in Childhood: Analysis of Hypertensive Phenotype.

    Science.gov (United States)

    García-Espinosa, Victoria; Curcio, Santiago; Marotta, Marco; Castro, Juan M; Arana, Maite; Peluso, Gonzalo; Chiesa, Pedro; Giachetto, Gustavo; Bia, Daniel; Zócalo, Yanina

    2016-10-01

    The aims were to determine whether children's high peripheral blood pressure states (HBP) are associated with increased central aortic blood pressure (BP) and to characterize hemodynamic and vascular changes associated with HBP in terms of changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR) and net and relative contributions of reflected waves to the aortic pulse amplitude. We included 154 subjects (mean age 11; range 4-16 years) assigned to one of two groups: normal peripheral BP (NBP, n = 101), defined as systolic and diastolic BP wave-derived parameters (augmentation index, forward and backward wave components' amplitude) were measured using gold-standard techniques, applanation tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). Independent of the presence of dyslipidemia and/or obesity, aortic systolic and pulse BP were higher in HBP than in NBP children. The increase in central BP could not be explained by an increase in the relative contribution of reflections to the aortic pressure wave, higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP would be explained by an increase in the amplitude of both incident and reflected wave components.

  13. Incommensurate atomic density waves in the high-pressure IVb phase of barium

    Directory of Open Access Journals (Sweden)

    Alla Arakcheeva

    2017-03-01

    Full Text Available The host–guest structures of elements at high pressure discovered a decade ago still leave many open questions due to the lack of precise models based on full exploitation of the diffraction data. This concerns in particular Ba IV, which is stable in the range 12–45 GPa. With the example of phase Ba IVb, which is characterized here for the first time, a systematic analysis is presented of possible host–guest structure models based on high-quality single-crystal diffraction data obtained with synchrotron radiation at six different pressures between 16.5 and 19.6 GPa. It is shown that a new incommensurately modulated (IM structure model better fits the experimental data. Unlike the composite models which are commonly reported for the Ba IV phases, the IM model reveals a density wave and its pressure-dependent evolution. The crucial role played by the selected model in the interpretation of structure evolution under pressure is discussed. The findings give a new experimental basis for a better understanding of the nature of host–guest structures.

  14. Generation of shock-free pressure waves in shaped resonators by boundary driving.

    Science.gov (United States)

    Luo, C; Huang, X Y; Nguyen, N T

    2007-05-01

    Investigation of high amplitude pressure oscillations generated by boundary driving in shaped resonators has been carried out both theoretically and experimentally. In the theoretical modeling, the acoustic resonance in an axisymmetric resonator is studied by the Galerkin method. The resonator is exponentially expanded and the boundary driving is provided by a piston at one end. The pressure wave forms, amplitudes, resonance frequencies, and ratio of pressures at the two ends of the resonator are calculated for various expansion flare constants and driving strengths. These results are partially compared with those generated by shaking the resonator. They are also verified in the experiment, in which an exponentially expanded resonator is connected to a speaker box functioning as the piston. The experiment is further extended to a horn-shaped resonator with a rectangular cross section. The boundary driving in this case is generated by a circular piezoelectric disk, which forms one sidewall of the resonator cavity. The characteristics of axisymmetric resonators, such as the resonance frequency and amplitude ratio of pressures at the two ends, are observed in this low aspect ratio rectangular resonator with the sidewall driving.

  15. The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

    Science.gov (United States)

    Park, Suhyun; Yoon, Heechul; Larin, Kirill V.; Emelianov, Stanislav Y.; Aglyamov, Salavat R.

    2017-02-01

    Intraocular pressure (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic wave velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic wave velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear wave elasticity imaging. To generate and then image the elastic wave propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic wave velocity in the cornea increased from 0.96  ±  0.30 m s-1 to 6.27  ±  0.75 m s-1 as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic wave velocity in the crystalline lens with the minimum and the maximum speeds of 1.44  ±  0.27 m s-1 and 2.03  ±  0.46 m s-1, respectively. This study shows that ultrasound shear wave elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.

  16. Vibration and pressure wave therapy for calf strains: a proposed treatment.

    Science.gov (United States)

    Saxena, Amol; St Louis, Marie; Fournier, Magali

    2013-04-01

    Calf (lower leg) strains have a variety of treatment regimens with variable outcomes and return to activity (RTA) time frames. These injuries involve disruption of portions or the entire gastrocnemius-soleus myo-tendinous complex. Conservative treatment initially consists of rest, ice, compression, elevation (RICE). Immediately following calf injury, patients can utilize cryotherapy, massage, passive range of motion, and progressive exercise. In general, Grade I through Grade III calf strains can take up to 6 weeks before the athlete can return to training. It can also involve the loss of more than 50% of muscle integrity. Recently, vibration therapy and radial pressure waves have been utilized to treat muscular strains and other myo-tendinous injuries that involve trigger points. Studies have suggested vibration therapy with rehabilitation can increase muscle strength and flexibility in patients. Segmental vibration therapy (SVT) is treatment to a more focal area. Vibration therapy (VT) is applied directly to the area of injury. VT is a mechanical stimulus that is thought to stimulate the sensory receptors, as well as decrease inflammatory cells and receptors. Therefore, VT could be a valuable tool in treating athlete effectively and decreasing their recovery time. The purpose of this paper is to give the reader baseline knowledge of VT and propose a treatment protocol for calf strains using this technology along with radial pressure waves.

  17. Experimental determination of radiated internal wave power without pressure field data

    CERN Document Server

    Lee, Frank M; Swinney, Harry L; Morrison, P J

    2014-01-01

    We present a method to determine, using only velocity field data, the time-averaged energy flux $\\left$ and total radiated power $P$ for two-dimensional internal gravity waves. Both $\\left$ and $P$ are determined from expressions involving only a scalar function, the stream function $\\psi$. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method agree to within 0.5% with results obtained using pressure and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and pressure if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife ed...

  18. Development of a Two-Dimensional Implicit Interior Ballistics Code

    Science.gov (United States)

    1980-01-01

    the universal gas constant, W is the gas molecular weight, u m and n is the covolume factor, which is composition dependent . Following Gough (Ref...c is dependent on the gas composition but not temperature. v The static enthalpy is then h = p e + p The specific heat at constant pressure is...Gun Interior Ballistics Transient Combustion Time- dependent Adaptive Grid 20, ABST’RACT (Cazrt&au:e _. .. ._._ lliO 11 ~ llltld ldenllly by block

  19. Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

    Directory of Open Access Journals (Sweden)

    C. L. Gomez-Heredia

    2017-01-01

    Full Text Available Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen’s number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorrpressure reduces. The obtained results show that the proposed methodology can be used to study the molecular dynamics in gases supporting diffusive and ballistic heat transport.

  20. P-wave velocities of main upper mantle minerals at high temperature and high pressure and its geological implication

    Institute of Scientific and Technical Information of China (English)

    宋茂双; 谢鸿森; 郑海飞; 徐有生; 郭捷; 许祖鸣

    1996-01-01

    At 0 - 5.0GPa and room temperature to 1400℃, the P-wave velocities of olivine, clinopyroxene and orthopyroxene, which are three common minerals from upper mantle, are measured under both simulated oceanic and continental geothermal gradients. The experimental results indicate that the P-wave velocities of these minerals increase with depth under both geothermal gradients. This implicates that pressure is more important than temperature in deep earth in controlling the P-wave velocities of mantle minerals, but the increase of temperature has greater effect on P-wave velocities of main mantle minerals at greater depth than at smaller depth. At low pressure, the measured P-wave velocities of mantle minerals are smaller than their true values due to fracturing, compaction process and recrystallization of mineral powder. The true P-wave velocities of mantle minerals can be obtained at lower pressure by the extrapolation of measured velocities at a high pressure. At higher depth, all these three minerals sho

  1. LIGHT PRESSURE: Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    Science.gov (United States)

    Guzatov, D. V.; Gaida, L. S.; Afanas'ev, Anatolii A.

    2008-12-01

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves.

  2. Computational Analysis of the Compressible Flow Driven by a Piston in a Ballistic Range

    Institute of Scientific and Technical Information of China (English)

    G. Rajesh; R. Mishra; H. G. Kang; H. D. Kim

    2007-01-01

    The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics and aeroballistics, since it can create an extremely high-pressure state in very short time. Since the operation of the ballistic range includes many complicated phenomena, each process should be understood in detail for the performance enhancement of the device. One of the main processes which have significant influence on the device performance is the compression process of the driver gas. Most of the studies available in this field hardly discuss this phenomenon in detail and thus lack a proper understanding of its effect on the whole system performance. In the present study, a computational analysis has been made to investigate the fluid dynamic aspects of the compression process in the pump tube of a ballistic range and to assess how it affects the performance of the ballistic range, The results obtained are validated with the available experimental data. In order to evaluate the system performance, several performance parameters are defined. Effect of a shock tube added in between the pump tube and launch tube on the performance of the ballistic range is also studied analytically. Performance of the ballistic range could be significantly improved by the proper selection of the pump tube and high-pressure tube parameters and the addition of the shock tube.

  3. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2009-04-01

    Full Text Available In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

  4. One Dimensional Ballistic Electron Transport

    Directory of Open Access Journals (Sweden)

    Thomas K J

    2009-10-01

    Full Text Available Research in low-dimensional semiconductor systems over the last three decades has been largely responsible for the current progress in the areas of nanoscience and nanotechnology. The ability to control and manipulate the size, the carrier density, and the carrier type in two-, one-, and zero- dimensional structures has been widely exploited to study various quantum transport phenomena. In this article, a brief introduction is given to ballistic electron transport in one-dimensional quantum wires.

  5. Reference ballistic imaging database performance.

    Science.gov (United States)

    De Kinder, Jan; Tulleners, Frederic; Thiebaut, Hugues

    2004-03-10

    Ballistic imaging databases allow law enforcement to link recovered cartridge cases to other crime scenes and to firearms. The success of these databases has led many to propose that all firearms in circulation be entered into a reference ballistic image database (RBID). To assess the performance of an RBID, we fired 4200 cartridge cases from 600 9mm Para Sig Sauer model P226 series pistols. Each pistol fired two Remington cartridges, one of which was imaged in the RBID, and five additional cartridges, consisting of Federal, Speer, Winchester, Wolf, and CCI brands. Randomly selected samples from the second series of Remington cartridge cases and from the five additional brands were then correlated against the RBID. Of the 32 cartridges of the same make correlated against the RBID, 72% ranked in the top 10 positions. Likewise, of the 160 cartridges of the five different brands correlated against the database, 21% ranked in the top 10 positions. Generally, the ranking position increased as the size of the RBID increased. We obtained similar results when we expanded the RBID to include firearms with the same class characteristics for breech face marks, firing pin impressions, and extractor marks. The results of our six queries against the RBID indicate that a reference ballistics image database of new guns is currently fraught with too many difficulties to be an effective and efficient law enforcement tool.

  6. The transfer of atmospheric-pressure ionization waves via a metal wire

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yang; Liu, Dongping, E-mail: Dongping.liu@dlnu.edu.cn [Liaoning Key Lab of Optoelectronic Films & Materials, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Wang, Wenchun [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Peng, Yifeng; Niu, Jinhai; Bi, Zhenhua; Ji, Longfei; Song, Ying; Wang, Xueyang; Qi, Zhihua [Liaoning Key Lab of Optoelectronic Films & Materials, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China)

    2016-01-15

    Our study has shown that the atmospheric-pressure He ionization waves (IWs) may be transferred from one dielectric tube (tube 1) to the other one (tube 2) via a floating metal wire. The propagation of IWs along the two tubes is not affected by the diameter of a floating metal wire, however, their propagation is strongly dependent on the length of a floating metal wire. The propagation of one IW along the tube 1 may result in the second IW propagating reversely inside the tube in vicinity of a floating metal wire, which keeps from their further propagation through the tube 1. After they merge together as one conduction channel inside the tube 1, the transferred plasma bullet starts to propagate along the tube 2. The propagation of transferred plasma bullets along the tube 2 is mainly determined by the capacitance and inductance effects, and their velocity and density can be controlled by the length of a floating metal wire.

  7. One-Dimensional Simulation of the Pressure Wave near the Exit of a High-Speed Train Tunnel

    Institute of Scientific and Technical Information of China (English)

    杨宇光; 朱克勤; 席葆树

    2001-01-01

    The one-dimensional (1-D) unsteady flow induced by a high-speed train entering a tunnel isnumerically studied by the method of characteristics. The tube area is dependent on time and distance. Theenergy equation used by Kage et al. is corrected to avoid the conflict with the isentropic assumption. Theeffect of the tunnel hood on the pressure wave is studied near the tunnel exit. Results show that the tunnel hoodis useful in reducing the peak value and the time derivative of the pressure wave.``

  8. Pressure-induced quenching of the charge-density-wave state observed by x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sacchetti, A.

    2010-05-03

    We report an x-ray diffraction study on the charge-density-wave (CDW) LaTe{sub 3} and CeTe{sub 3} compounds as a function of pressure. We extract the lattice constants and the CDW modulation wave-vector, and provide direct evidence for a pressure-induced quenching of the CDW phase. We observe subtle differences between the chemical and mechanical compression of the lattice. We account for these with a scenario where the effective dimensionality in these CDW systems is dependent on the type of lattice compression and has a direct impact on the degree of Fermi surface nesting and on the strength of fluctuation effects.

  9. Characteristic enhancement of blood pressure V-shaped waves in sinoaortic-denervated rats in a conscious and quiet state.

    Science.gov (United States)

    Chang, Huan; Gu, Hong-Xia; Gong, Min; Han, Ji-Ju; Wang, Yun; Xia, Zuo-Li; Zhao, Xiao-Min

    2016-11-08

    A hemodynamic feature of chronic sinoaortic-denervated (SAD) rats is the increase in blood pressure variability (BPV) without significant changes in the average level of blood pressure (BP). The current study was designed to investigate the changes in BP V-shaped waves (V waves) in SAD rats. Sprague-Dawley (SD) rats were divided into 2 groups: SAD rats and sham-operated rats (n=13). Hemodynamics measurements were obtained in conscious, freely moving rats, four weeks after sinoaortic denervation or sham operation. V wave indices were evaluated in rats in both conscious and quiet states. Additionally, normal and high BPV was simulated by the production of V waves with different amplitudes. The results showed that the V wave amplitude was dramatically increased, with a significantly prolonged duration and reduced frequency in SAD rats. V wave BPV in SAD rats was significantly increased, though BP remained unchanged. The twenty-four hour BPV in all rats was positively correlated with amplitude, duration time and V wave BPV and negatively correlated with frequency. The systolic BP spectral powers in the low frequency range (0.38-0.45 Hz) were significantly reduced in the V waves of SAD rats. Moreover, there was a remarkable increase in mean BPV and a normal mean BP after simulating high BPV in SAD rats. These results suggest that enhancement of V waves might be a waveform character of BP in SAD rats in both the conscious and quiet states. These types of V waves appear to be related to a depression of sympathetic regulation of BP induced by sinoaortic denervation.

  10. Comparison of Blood Pressure and Thermal Responses in Rats Exposed to Millimeter Wave Energy or Environmental Heat

    Science.gov (United States)

    2005-12-22

    nerve injury rats exhibit millimeter wave length: potential occupational safety issues relating to surface thermal hyperalgesia on an automated...May 2006 1 Journal Article I Aug 2005 - May 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Comparison of Blood Pressure and Thermal Responses in Rats...Z39.18 5-1 •ATEThENTA SHOCK, Vol. 25, No. 6, pp. 625-632, 2006 Approved for Public Release Distribution Unlimited COMPARISON OF BLOOD PRESSURE AND THERMAL

  11. Analytical Stationary Acoustic Wave in a Liquid over Which a Moving Pressure Runs

    Directory of Open Access Journals (Sweden)

    André Langlet

    2010-01-01

    Full Text Available This paper presents an analytical study of the stationary response of a liquid loaded on its free surface by an ideal pressure step moving in a constant direction at a constant velocity. The acoustic pressure in the liquid is found, in four different examples, by means of the Fourier Transform. Two loading regimes are considered; subsonic and supersonic. Two configurations of liquid domains are also studied, the first one is a half infinite space while the second one is bounded by a rigid bottom at a finite depth. For the two supersonic cases, a simple reasoning based on the existence of a front of discontinuity in the liquid and on the property of reflection of waves confirms the result of the mathematical investigations. The results obtained for the steady state case are of intererest, even when the loading is not exactly stationary, such as the presure produced by an explosion occurring in the vicinity of the surface of a liquid. Two numerically resolved examples are presented, which confirm this assumption.

  12. Design and Experiment for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine

    Institute of Scientific and Technical Information of China (English)

    JI Chang-wei; ZHAO Yong; MA Hui; HAN Ai-min; LI Chao

    2007-01-01

    NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging (PWS). The diesel engine matched with PWS needs redesigning its exhaust pipes. Except for meeting the installation requirements, the exhaust gas must be stable in pressure before rushing into PWS. In this paper the lateral and center ported divergent exhaust pipes are designed, modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume. Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS. Moreover, the optimal exhaust pipes are determined comprehensively and cast for engine test. Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds. The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust pipes.

  13. Impulses and pressure waves cause excitement and conduction in the nervous system.

    Science.gov (United States)

    Barz, Helmut; Schreiber, Almut; Barz, Ulrich

    2013-11-01

    It is general accepted, that nerval excitement and conduction is caused by voltage changes. However, the influx of fluid into an elastical tube releases impulses or pressure waves. Therefore an influx of ion currents, respectively fluid motions into the elastic neuronal cells and fibres also induce impulses. This motion of charge carriers are measured by voltage devices as oscillations or action potentials, but the voltage changes may be an epiphenomenon of the (mechanical) impulses. Impulse waves can have a high speed. As stiffer or inelastic a tube wall, the greater is the speed of the impulse. Myelin sheaths cause a significant stiffening of the nerve fibre wall and myelinated fibres have a conduction velocity up to 120 m/s. The influx of fluid at the nodes of Ranvier intensifies periodically the impulse wave in the nerve fibres. The authors suggest that also the muscle end-plate acts as a conductor of axonal impulses to the inner of the muscle fibres and that the exocytosis of acetylcholine into the synaptic cleft may be an amplifier of the axonal impulse. It is discussed that intracellular actin filaments may also influence motions at the neuronal membrane. Many sensory nerve cells are excited due to exogenous or endogenous mechanical impulses. It may plausible that such impulses are conducted directly to the sensory nerve cell bodies in the dorsal root ganglia without the transformation in electric energy. Excitation conduction happens without noteworthy energy consumption because the flow of ion currents through the membranes takes place equivalent to the concentration gradient. Impulse waves cause short extensions of the lipid membranes of the cell- and fibres walls and therefore they can induce opening and closing of the included ion channels. This mechanism acts to "voltage gated" and "ligand-gated" channels likewise. The concept of neuronal impulses can be helpful to the understanding of other points of neurophysiology or neuronal diseases. This includes

  14. Optimally accurate thermal-wave cavity photopyroelectric measurements of pressure-dependent thermophysical properties of air: theory and experiments.

    Science.gov (United States)

    Kwan, Chi-Hang; Matvienko, Anna; Mandelis, Andreas

    2007-10-01

    An experimental technique for the measurement of thermal properties of air at low pressures using a photopyroelectric (PPE) thermal-wave cavity (TWC) was developed. In addition, two theoretical approaches, a conventional one-dimensional thermal-wave model and a three-dimensional theory based on the Hankel integral, were applied to interpret the thermal-wave field in the thermal-wave cavity. The importance of radiation heat transfer mechanisms in a TWC was also investigated. Radiation components were added to the purely conductive model by linearizing the radiation heat transfer component at the cavity boundary. The experimental results indicate that the three-dimensional model is necessary to describe the PPE signal, especially at low frequencies where thermal diffusion length is large and sideways propagation of the thermal-wave field becomes significant. Radiation is found to be the dominant contributor of the PPE signal at high frequencies and large cavity lengths, where heat conduction across the TWC length is relatively weak. The three-dimensional theory and the Downhill Simplex algorithm were used to fit the experimental data and extract the thermal diffusivity of air and the heat transfer coefficient in a wide range of pressures from 760 to 2.6 Torr. It was shown that judicious adjustments of cavity length and computational best fits to frequency-scanned data using three-dimensional photopyroelectric theory lead to optimally accurate value measurements of thermal diffusivity and heat transfer coefficient at various pressures.

  15. A new climate index controlling winter wave activity along the Atlantic coast of Europe: The West Europe Pressure Anomaly

    Science.gov (United States)

    Castelle, Bruno; Dodet, Guillaume; Masselink, Gerd; Scott, Tim

    2017-02-01

    A pioneering and replicable method based on a 66-year numerical weather and wave hindcast is developed to optimize a climate index based on the sea level pressure (SLP) that best explains winter wave height variability along the coast of western Europe, from Portugal to UK (36-52°N). The resulting so-called Western Europe Pressure Anomaly (WEPA) is based on the sea level pressure gradient between the stations Valentia (Ireland) and Santa Cruz de Tenerife (Canary Islands). The WEPA positive phase reflects an intensified and southward shifted SLP difference between the Icelandic low and the Azores high, driving severe storms that funnel high-energy waves toward western Europe southward of 52°N. WEPA outscores by 25-150% the other leading atmospheric modes in explaining winter-averaged significant wave height, and even by a largest amount the winter-averaged extreme wave heights. WEPA is also the only index capturing the 2013/2014 extreme winter that caused widespread coastal erosion and flooding in western Europe.

  16. The Cooperative Ballistic Missile Defence Game

    NARCIS (Netherlands)

    Evers, L.; Barros, A.I.; Monsuur, H.

    2013-01-01

    The increasing proliferation of ballistic missiles and weapons of mass destruction poses new risks worldwide. For a threatened nation and given the characteristics of this threat a layered ballistic missile defence system strategy appears to be the preferred solution. However, such a strategy involv

  17. Geometric Scaling for a Detonation Wave Governed by a Pressure-Dependent Reaction Rate and Yielding Confinement

    CERN Document Server

    Jianling, Li; Higgins, Andrew J

    2014-01-01

    The propagation of detonation waves in reactive media bounded by an inert, compressible layer is examined via computational simulations in two different geometries, axisymmetric cylinders and two dimensional, planar slabs. For simplicity, an ideal gas equation of state is used with a pressure-dependent reaction rate that results in a stable detonation wave structure. The detonation is initiated as an ideal Chapman-Jouguet (CJ) detonation with a one-dimensional structure, and then allowed to propagate into a finite diameter or thickness layer of explosive surrounded by an inert layer. The yielding confinement of the inert layer results in the detonation wave decaying to a sub-CJ steady state velocity or failing entirely. Simulations are performed with different values of the reaction rate pressure exponent (n = 2 and 3) and different impedance confinement (greater than, less than, and equal to the confinement of the explosive). The velocity decrement and critical dimension (critical diameter or thickness) are ...

  18. A Novel Dynamic Model for Predicting Pressure Wave Velocity in Four-Phase Fluid Flowing along the Drilling Annulus

    Directory of Open Access Journals (Sweden)

    Xiangwei Kong

    2015-01-01

    Full Text Available A dynamic pressure wave velocity model is presented based on momentum equation, mass-balance equation, equation of state, and small perturbation theory. Simultaneously, the drift model was used to analyze the flow characteristics of oil, gas, water, and drilling fluid multiphase flow. In addition, the dynamic model considers the gas dissolution, virtual mass force, drag force, and relative motion of the interphase as well. Finite difference and Newton-Raphson iterative are introduced to the numerical simulation of the dynamic model. The calculation results indicate that the wave velocity is more sensitive to the increase of gas influx rate than the increase of oil/water influx rate. Wave velocity decreases significantly with the increase of gas influx. Influenced by the pressure drop of four-phase fluid flowing along the annulus, wave velocity tends to increase with respect to well depth, contrary to the gradual reduction of gas void fraction at different depths with the increase of backpressure (BP. Analysis also found that the growth of angular frequency will lead to an increase of wave velocity at low range. Comparison with the calculation results without considering virtual mass force demonstrates that the calculated wave velocity is relatively bigger by using the presented model.

  19. Signal Analysis and Waveform Reconstruction of Shock Waves Generated by Underwater Electrical Wire Explosions with Piezoelectric Pressure Probes.

    Science.gov (United States)

    Zhou, Haibin; Zhang, Yongmin; Han, Ruoyu; Jing, Yan; Wu, Jiawei; Liu, Qiaojue; Ding, Weidong; Qiu, Aici

    2016-04-22

    Underwater shock waves (SWs) generated by underwater electrical wire explosions (UEWEs) have been widely studied and applied. Precise measurement of this kind of SWs is important, but very difficult to accomplish due to their high peak pressure, steep rising edge and very short pulse width (on the order of tens of μs). This paper aims to analyze the signals obtained by two kinds of commercial piezoelectric pressure probes, and reconstruct the correct pressure waveform from the distorted one measured by the pressure probes. It is found that both PCB138 and Müller-plate probes can be used to measure the relative SW pressure value because of their good uniformities and linearities, but none of them can obtain precise SW waveforms. In order to approach to the real SW signal better, we propose a new multi-exponential pressure waveform model, which has considered the faster pressure decay at the early stage and the slower pressure decay in longer times. Based on this model and the energy conservation law, the pressure waveform obtained by the PCB138 probe has been reconstructed, and the reconstruction accuracy has been verified by the signals obtained by the Müller-plate probe. Reconstruction results show that the measured SW peak pressures are smaller than the real signal. The waveform reconstruction method is both reasonable and reliable.

  20. Relations between diabetes, blood pressure and aortic pulse wave velocity in haemodialysis patients

    DEFF Research Database (Denmark)

    Peters, Christian Daugaard; Kjærgaard, Krista Dybtved; Dzeko, Mirela;

    Diabetes (DM) is common in haemodialysis (HD) patients and affects both blood pressure (BP) and arterial stiffness. Carotid femoral pulse wave velocity (PWV) reflects the stiffness of the aorta and is regarded as a strong risk factor for cardiovascular (CV) mortality in HD patients. However, PWV...... is highly influenced by the BP-level. Higher PWV-values among HD patients with DM could reflect a higher BP-level rather than increased arterial stiffness. The aim of this study was to investigate the effect of DM on BP and PWV in a group of HD patients. BP and PWV were measured in 66 HD patients without DM...... (HD) and 32 HD patients with DM (HD+DM). The SphygmoCor system was used for estimation of PWV. HD-duration, age, gender and BP medication were similar in the two groups. Mean DM-duration was 23±11 years and 25(78%) had type 2 DM. HD+DM had higher BMI (26±5 vs. 29±5 kg/m2, p=0.02), systolic BP (142...

  1. Acoustic model of micro-pressure wave emission from a high-speed train tunnel

    Science.gov (United States)

    Miyachi, T.

    2017-03-01

    The micro-pressure wave (MPW) radiated from a tunnel portal can, if audible, cause serious problems around tunnel portals in high-speed railways. This has created a need to develop an acoustic model that considers the topography around a radiation portal in order to predict MPWs more accurately and allow for higher speed railways in the future. An acoustic model of MPWs based on linear acoustic theory is developed in this study. First, the directivity of sound sources and the acoustical effect of topography are investigated using a train launcher facility around a portal on infinitely flat ground and with an infinite vertical baffle plate. The validity of linear acoustic theory is then discussed through a comparison of numerical results obtained using the finite difference method (FDM) and experimental results. Finally, an acoustic model is derived that considers sound sources up to the second order and Green's function to represent the directivity and effect of topography, respectively. The results predicted by this acoustic model are shown to be in good agreement with both numerical and experimental results.

  2. Shock wave equation of state experiments at multi-TPa pressures on NIF

    Science.gov (United States)

    Celliers, P. M.; Fratanduono, D. E.; Peterson, J. L.; Meezan, N. B.; MacKinnon, A. J.; Braun, D. G.; Millot, M.; Fry, J.; Boehm, K. J.; Sterne, P. A.; Collins, G. W.; Nikroo, A.; Fitzsimmons, P.

    2015-11-01

    The National Ignition Facility provides an unprecedented capability to generate steady, planar, ultra-high pressure shock waves (up to 10 TPa or more) in solid samples. Building on successful laser shock equation of state experiments performed on a variety of other laser facilities, we have designed and fielded experiments to perform impedance match experiments on samples of C, Be, SiO2 and CH, in the range of 3 to 7 TPa. The experiments use a line-imaging VISAR as the primary diagnostic to measure the shock velocity in an Al reference standard and in an array of the four samples. Initial tests with the line-imaging VISAR show that the NIF is capable of driving shocks that are steady to better than 2% in velocity for several ns, with smooth planar breakout patterns over a 2 mm diameter spot. Hugoniot data points will be compared to current equation-of-state models for the various materials under study. This work was performed under the auspices of the U.S. Department of Energy by LLNL under contract DE-AC52-07NA27344.

  3. Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

    Institute of Scientific and Technical Information of China (English)

    杨树锋; 陈汉林; 姜继双; 竺国强; 谢鸿森; 侯渭; 张月明; 徐惠刚

    1997-01-01

    The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure hoost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The "softening point" of compressional wave velocity ( Vp) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of "softening", Vp after "softening" and the percentage of Vp’ s drop around the "softening point" for two types of granitoids are obviously different. The depth of "softening" is 15 km approximately and Vp after "softening" is 5. 62 km/s for S-type granitoid. But for I-type granitoid the depth of "softening" is 26 km approximately and Vp after "softening" is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the "softening" of elastic-wave velocity is caused by t

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

    Energy Technology Data Exchange (ETDEWEB)

    Hull, Lawrence Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Miller, Phillip Isaac [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moro, Erik Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-28

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

  5. Numerical simulation of the nonlinear ultrasonic pressure wave propagation in a cavitating bubbly liquid inside a sonochemical reactor.

    Science.gov (United States)

    Dogan, Hakan; Popov, Viktor

    2016-05-01

    We investigate the acoustic wave propagation in bubbly liquid inside a pilot sonochemical reactor which aims to produce antibacterial medical textile fabrics by coating the textile with ZnO or CuO nanoparticles. Computational models on acoustic propagation are developed in order to aid the design procedures. The acoustic pressure wave propagation in the sonoreactor is simulated by solving the Helmholtz equation using a meshless numerical method. The paper implements both the state-of-the-art linear model and a nonlinear wave propagation model recently introduced by Louisnard (2012), and presents a novel iterative solution procedure for the nonlinear propagation model which can be implemented using any numerical method and/or programming tool. Comparative results regarding both the linear and the nonlinear wave propagation are shown. Effects of bubble size distribution and bubble volume fraction on the acoustic wave propagation are discussed in detail. The simulations demonstrate that the nonlinear model successfully captures the realistic spatial distribution of the cavitation zones and the associated acoustic pressure amplitudes.

  6. Numerical simulation of magnetospheric ULF waves excited by positive and negative impulses of solar wind dynamic pressure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The sources of ultra low frequency (ULF) waves in the magnetosphere are generally believed to be either the external solar wind perturbations or the internal plasma instabilities. When a sudden impulse of the solar wind dynamic pressure impinges on the magnetopause, ULF waves might be excited and thus the solar wind energy is transported into the earth’s magnetosphere. In this paper, we study the ULF waves excited by different kinds of sudden solar wind pressure impulses through an MHD simulation. We primarily focus on the responses of the earth’s magnetosphere to positive/negative impulses of solar wind dynamic pressure, and positive-negative impulse pairs. The simulation results show that the ULF waves excited by positive and negative impulse have the same amplitude and frequency, with 180° difference in phase, if the amplitude and durations of the input impulses are the same. In addition, it is found that field line resonances (FLRs) occur at certain L-shell regions of the earth’s magneto-sphere after the impact of different positive-negative impulse pairs, which appear to be related to the duration of the impulses and the time interval between the sequential impulses. Another result is that the energy from the solar wind could be transported deeper into the inner magnetosphere by an impulse pair than by a single pulse impact. The results presented in this paper could help us to better understand how energy is transported from solar wind to the earth’s magnetosphere via ULF waves. Also, these results provide some new clues to understanding of how energetic particles in the inner magnetosphere response to different kinds of solar wind pressure impulse impacts including inter-planetary shocks.

  7. Prediction of Impact Pressure Induced by Breaking Waves on Marine Systems in Random Seas.

    Science.gov (United States)

    1983-07-01

    probability density function of the excursion and time interval for Type I and Type II excursions U Figure 6 Spectral density function of significant wave...the wave spectral density function a = 0.196 for r-sec-units Wave breaking takes place in the region where the wave excursion exceeds the criterion...double amplitude), /m. with = A "A = magnitude of the positive maxima mo = area under the spectral density function The joint probability density

  8. Direct analysis of dispersive wave fields from near-field pressure measurements

    NARCIS (Netherlands)

    Horchens, L.

    2011-01-01

    Flexural waves play a significant role for the radiation of sound from plates. The analysis of flexural wave fields enables the detection of sources and transmission paths in plate-like structures. The measurement of these wave fields can be carried out indirectly by means of near-field acoustic hol

  9. Preservation and storage of prepared ballistic gelatine.

    Science.gov (United States)

    Mattijssen, E J A T; Alberink, I; Jacobs, B; van den Boogaard, Y

    2016-02-01

    The use of ballistic gelatine, generally accepted as a human muscle tissue simulant in wound ballistic studies, might be improved by adding a preservative (Methyl 4-hydroxybenzoate) which inhibits microbial growth. This study shows that replacing a part of the gelatine powder by the preservative does not significantly alter the penetration depth of projectiles. Storing prepared blocks of ballistic gelatine over time decreased the penetration depth of projectiles. Storage of prepared gelatine for 4 week already showed a significant effect on the penetration depth of projectiles.

  10. Assessment of Ballistic Performance for Transparent Material

    Directory of Open Access Journals (Sweden)

    Basim M. Fadhil

    2014-05-01

    Full Text Available A finite element method was used to investigate the ballistic behavior of Polymethylmethacrylate (PMMA under impact loading by spherical steel projectile with different ranges of velocities. Three different target thicknesses were used in the experimental and the numerical works. A mathematical model has been used for the ballistic limit based on the experimental results. It has been found that projectile velocity and target thickness play an important role in the ballistic behavior of PMMA. A good agreement was found between the numerical, experimental, and the analytical result.

  11. The mechanical response of piles with consideration of pile-soil interactions under a periodic wave pressure

    Institute of Scientific and Technical Information of China (English)

    朱峰; 徐卫亚; 王环玲

    2014-01-01

    The pile-soil interaction under wave loads is an extremely complex and difficult issue in engineering. In this study, a physical model test is designed based on the principle of the gravity similarity to obtain time histories of wave forces of unsteady regular waves, and to measure the magnitude and the distribution of wave forces acting on the piles. A numerical model and relevant numerical methods for the pile-soil contact surface are adopted based on the principles of elastic dynamics. For a practical project, the time histories of wave forces on the piles are obtained through physical model tests. The deformations of the piles in the pile-soil interactions and the distribution of the bending moment on the piles are studied. It is shown that, with the increase of the period of wave pressures, the absolute value of the horizontal displacement of the piles increases, the embedment depth of the piles increases, and the scope of influence of soils increases. The change of the bending moment on the piles is consistent with that of its theoretical results, and the proposed numerical method can very well simulate the properties of the piles.

  12. Ballistic Fracturing of Carbon Nanotubes.

    Science.gov (United States)

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome.

  13. Numerical simulation on the propagation of pressure waves in a kinked duct; Kussetsu kannai wo denpasuru shogekiha no suchi simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, I. [Traffic Safety and Nuisance Research Inst., Tokyo (Japan); Higashino, F. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Faculty of Technology

    1996-08-25

    In order to simulate behavior of shock wave propagating in a square kinked duct, a numerical method based on the TVD scheme was developed. Both initial conditions and mesh sizes were tested to simulate the experimental results obtained from exploding wire experiments. Numerical density contours showed qualitatively good agreement with experimental results of schlieren photographs. Measured pressure ratios across the shock front also showed good agreement when they were compared quantitatively with computations along the upper edge, lower edge and center line of the duct. The present method using a narrow high pressure region in a duct as an initial condition was shown to be useful for predicting blast wave decay. 6 refs., 11 figs., 1 tab.

  14. Pressure waves in liquid mercury target from pulsed heat loads and the possible way controlling their effects

    Energy Technology Data Exchange (ETDEWEB)

    Ni, L.; Skala, K. [Paul Scherrer Institute, Villingen (Switzerland)

    1996-06-01

    In ESS project liquid metals are selected as the main target for the pulsed spallation neutron source. Since the very high instantaneous energy is deposited on the heavy molten target in a very short period time, pressure waves are generated. They travel through the liquid and cause high stress in the container. Also, additional stress should be considered in the wall which is the result of direct heating of the target window. These dynamic processes were simulated with computational codes with the static response being analized first. The total resulting dynamic wall stress has been found to have exceeded the design stress for the selected container material. Adding a small amount of gas bubbles in the liquid could be a possible way to reduce the pressure waves.

  15. Ballistic Rail Gun Soft Recovery Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Ballistic Rail Gun Soft Recovery Facility accommodates a 155mm Howitzer, fired horizontally into a 104-foot long water trough to slow the projectile and recover...

  16. An experimental study of the self-healing behavior of ionomeric systems under ballistic impact tests

    Science.gov (United States)

    Grande, A. M.; Coppi, S.; Di Landro, L.; Sala, G.; Giacomuzzo, C.; Francesconi, A.; Rahman, M. A.

    2012-04-01

    This research deals with the investigation of the self-healing behavior after ballistic damage of ethylene-methacrylic acid ionomers and theirs blends with epoxidized natural rubber (ENR). The self-healing capability was studied by ballistic puncture tests under different experimental conditions as sample thickness, bullet speed, diameter and shape. Bullet speed ranging from few hundreds meters per second to few km/s were employed. The healing efficiency was evaluated by applying a pressure gradient trough the plates and by checking for possible flow at the damage zone. A morphology analysis of the impact area was made observing all samples by scanning electron microscope.

  17. Gunshot wounds:A review of ballistics related to penetrating trauma

    Institute of Scientific and Technical Information of China (English)

    SPanagiotis K Stefanopoulos; Georgios F Hadjigeorgiou; Konstantinos Filippakis; Dimitrios Gyftokostas

    2014-01-01

    Civilian gunshot injuries from handgun and rifle ammunition vary in severity depending on the anatomic location involved and the different effects from the ballistic properties of the penetrating projectiles.Ballistic factors such as the impact velocity and energy should not be considered in isolation, as their specific effects are determined by the interaction between the projectile and tissues.Increased tissue damage can result from tumbling of non-deforming rifle bullets and deformation of expanding bullets.Both of these mechanisms increase substantially the energy transfer to the wound and its diameter, also producing a pulsating temporary cavity associated with pressure changes within tissue.

  18. Failure analysis of high performance ballistic fibers

    OpenAIRE

    Spatola, Jennifer S

    2015-01-01

    High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mo...

  19. The association of 25(OH)D with blood pressure, pulse pressure and carotid–radial pulse wave velocity in African women

    OpenAIRE

    Iolanthé M Kruger; Schutte, Aletta E.; Huisman, Hugo W.; Van Rooyen, Johannes M.; Schutte, Rudolph; Malan, Leoné; Malan, Nicolaas T.; Carla M T Fourie; Kruger, Annamarie

    2013-01-01

    High susceptibility of the African population to develop cardiovascular disease obliges us to investigate possible contributing risk factors. Our aim was to determine whether low 25(OH)D status is associated with increased blood pressure and carotid-radial pulse wave velocity in black South African women. We studied 291 urban women (mean age: 57.5669.00 yrs.). 25(OH)D status was determined by serum 25(OH)D levels. Women were stratified into sufficient (.30 ng/ ml), and insufficien...

  20. Workbook for Predicting Pressure Wave and Fragment Effect of Exploding Propellent Tanks and Gas Storage Vessels

    Science.gov (United States)

    1975-11-01

    infermtrilon Is presented in the form of grasphs, tablas , and nouwraphs to allow easy esileuilaisu without reoourse to diffiult matthemnatical onsiililatlom...34Blast Wave Interactions from Multiple Fxplosions." Paper No. XII , Proceedinas of the Conference on Mechanisms of Explosion and Blast Waves, J

  1. Spatial Distribution of Wave Pressures on Seawave Slot-Cone Generator

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Frigaard, Peter

    2009-01-01

    above the other. Comprehensive 2D and 3D wave tank model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark) in the 3D deep water wave tank. The model scale used was 1:60 of the SSG prototype at the planned location of a pilot plant at the west coast of the island...

  2. Pressure measurements and an analytical model for laser-generated shock waves in solids at low irradiance

    CERN Document Server

    Romain, J P; Dayma, G; Boustie, M; Resseguier, T D; Combis, P

    2002-01-01

    Low amplitude shock waves (from 1 to 300 bar) have been generated in gold layers deposited on a quartz substrate, by laser pulses at an incident fluence from 0.4 to 4.0 J cm sup - sup 2. The quartz was used as a pressure gauge for recording the induced shock profile. At a fluence <1.4 J cm sup - sup 2 , the shock pressure does not exceed 10 bar and the shock front is followed by a tension peak typical of an absorption in solid state. An analytical model of the compression-tension process has been developed, accounting for shock pressure and shock profile evolution as a function of irradiation conditions and material properties. From this model a mechanical interpretation is given to previous observations of spalling of the irradiated target surface.

  3. Correlation of pulse wave velocity with left ventricular mass in patients with hypertension once blood pressure has been normalized

    Directory of Open Access Journals (Sweden)

    Siu H. Chan

    2012-02-01

    Full Text Available Vascular stiffness has been proposed as a simple method to assess arterial loading conditions of the heart which induce left ventricular hypertrophy (LVH. There is some controversy as to whether the relationship of vascular stiffness to LVH is independent of blood pressure, and which measurement of arterial stiffness, augmentation index (AI or pulse wave velocity (PWV is best. Carotid pulse wave contor and pulse wave velocity of patients (n=20 with hypertension whose blood pressure (BP was under control (<140/90 mmHg with antihypertensive drug treatment medications, and without valvular heart disease, were measured. Left ventricular mass, calculated from 2D echocardiogram, was adjusted for body size using two different methods: body surface area and height. There was a significant (P<0.05 linear correlation between LV mass index and pulse wave velocity. This was not explained by BP level or lower LV mass in women, as there was no significant difference in PWV according to gender (1140.1+67.8 vs 1110.6+57.7 cm/s. In contrast to PWV, there was no significant correlation between LV mass and AI. In summary, these data suggest that aortic vascular stiffness is an indicator of LV mass even when blood pressure is controlled to less than 140/90 mmHg in hypertensive patients. The data further suggest that PWV is a better proxy or surrogate marker for LV mass than AI and the measurement of PWV may be useful as a rapid and less expensive assessment of the presence of LVH in this patient population.

  4. Evaluation of the Colin STBP-680 at rest and during exercise: an automated blood pressure monitor using R-wave gating.

    OpenAIRE

    Bond, V.; Bassett, D R; Howley, E T; Lewis, J.; Walker, A J; Swan, P D; Tearney, R J; Adams, R.G.

    1993-01-01

    The application of automated blood pressure measurement during exercise has been limited by inaccuracies introduced by the effects of accompanying motion and noise. We evaluated a newly developed automated blood pressure monitor for measuring exercise blood pressure (Colin STBP-680; Colin, San Antonio, Texas, USA). The STBP-680 uses acoustic transduction with the assistance of the electrocardiogram R-wave to trigger the sampling period for blood pressure measurement. The automated monitor rea...

  5. Effect of environmental factors (wave exposure and depth) and anthropogenic pressure in the C sink capacity of Posidonia oceanica meadows

    KAUST Repository

    Mazarrasa, Inés

    2017-03-20

    Seagrass are among the most important natural carbon sinks on Earth with Posidonia oceanica (Mediterranean Sea) considered as the most relevant species. Yet, the number of direct measurements of organic carbon burial rates in P. oceanica is still scarce and the effect of local environmental factors remains largely unexplored. In addition, P. oceanica meadows are declining due to the increase in anthropogenic pressure in coastal areas during the last century. The aim of this study is to assess the recent carbon sink capacity of P. oceanica and particularly the effect of human pressure and two environmental factors, water depth and exposure to wave energy (based on a fetch index), on the carbon burial rate since 1900. We conducted an extensive survey of sediment cores in meadows distributed across a gradient of depth, fetch, and human pressure around The Balearic Islands. Sediment and carbon accumulation rates were obtained from 210Pb concentrations profiles. Top-30 centimeters carbon stocks (6.1 ± 1.4 kg C m−2) and burial rates (26 ± 6 g C m−2 yr1) varied up to fivefold across meadows. No significant effect of water depth in carbon burial rates was observed. Although fetch was significantly correlated with sediment mean grain size, confirming the effect of wave exposure in the patterns of sedimentation, fetch alone could not explain the differences in carbon burial rates among the meadows examined. Human pressure affected carbon burial rates, leading to increased rates since the onset of the rise in anthropogenic pressure, particularly so in sheltered meadows supporting high human pressure.

  6. The Importance of Pressure Sampling Frequency in Models for Determination of Critical Wave Loadingson Monolithic Structures

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Andersen, Thomas Lykke; Meinert, Palle

    2008-01-01

    This paper discusses the influence of wave load sampling frequency on calculated sliding distance in an overall stability analysis of a monolithic caisson. It is demonstrated by a specific example of caisson design that for this kind of analyses the sampling frequency in a small scale model could...... be as low as 100 Hz in model scale. However, for design of structure elements like the wave wall on the top of a caisson the wave load sampling frequency must be much higher, in the order of 1000 Hz in the model. Elastic-plastic deformations of foundation and structure were not included in the analysis....

  7. PROGRESS OF ACOUSTIC WAVE TECHNIQUE AND ITS APPLICATION IN UNDERGROUND PRESSURE MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    周楚良; 李新元; 张晓龙

    1994-01-01

    This paper carries out the experiment study on the correlation between full stress-strain process of rock samples and the acoustic parameter change of rock by using the measurement system of KS acoustic wave data processing device. On the spot, the stability of surrounding rock is studied by means of experiments on the relationship between the change process (from elastic to plastic failure zone) in surrounding rock of roadway and the change law of acoustic parameters of rock. These acoustic parameters include wave amplitude, spectral amplitude, spectrum area, spectral density, wave velocity and attenuation coefficient etc.

  8. Experimental study on the pressure and pulse wave propagation in viscoelastic vessel tubes-effects of liquid viscosity and tube stiffness.

    Science.gov (United States)

    Ikenaga, Yuki; Nishi, Shohei; Komagata, Yuka; Saito, Masashi; Lagrée, Pierre-Yves; Asada, Takaaki; Matsukawa, Mami

    2013-11-01

    A pulse wave is the displacement wave which arises because of ejection of blood from the heart and reflection at vascular bed and distal point. The investigation of pressure waves leads to understanding the propagation characteristics of a pulse wave. To investigate the pulse wave behavior, an experimental study was performed using an artificial polymer tube and viscous liquid. A polyurethane tube and glycerin solution were used to simulate a blood vessel and blood, respectively. In the case of the 40 wt% glycerin solution, which corresponds to the viscosity of ordinary blood, the attenuation coefficient of a pressure wave in the tube decreased from 4.3 to 1.6 dB/m because of the tube stiffness (Young's modulus: 60 to 200 kPa). When the viscosity of liquid increased from approximately 4 to 10 mPa·s (the range of human blood viscosity) in the stiff tube, the attenuation coefficient of the pressure wave changed from 1.6 to 3.2 dB/m. The hardening of the blood vessel caused by aging and the increase of blood viscosity caused by illness possibly have opposite effects on the intravascular pressure wave. The effect of the viscosity of a liquid on the amplitude of a pressure wave was then considered using a phantom simulating human blood vessels. As a result, in the typical range of blood viscosity, the amplitude ratio of the waves obtained by the experiments with water and glycerin solution became 1:0.83. In comparison with clinical data, this value is much smaller than that seen from blood vessel hardening. Thus, it can be concluded that the blood viscosity seldom affects the attenuation of a pulse wave.

  9. The ballistic transport instability in Saturn's rings III: numerical simulations

    CERN Document Server

    Latter, Henrik; Chupeau, Marie

    2014-01-01

    Saturn's inner B-ring and its C-ring support wavetrains of contrasting amplitudes but with similar length scales, 100-1000 km. In addition, the inner B-ring is punctuated by two intriguing `flat' regions between radii 93,000 km and 98,000 km in which the waves die out, whereas the C-ring waves coexist with a forest of plateaus, narrow ringlets, and gaps. In both regions the waves are probably generated by a large-scale linear instability whose origin lies in the meteoritic bombardment of the rings: the ballistic transport instability. In this paper, the third in a series, we numerically simulate the long-term nonlinear evolution of this instability in a convenient local model. Our C-ring simulations confirm that the unstable system forms low-amplitude wavetrains possessing a preferred band of wavelengths. B-ring simulations, on the other hand, exhibit localised nonlinear wave `packets' separated by linearly stable flat zones. Wave packets travel slowly while spreading in time, a result that suggests the obser...

  10. On the Role of Osmosis for Non-Linear Shock Waves f Pressure and Solute in Porous Media

    Science.gov (United States)

    Kanivesky, Roman; Salusti, Ettore; Caserta, Arrigo

    2013-04-01

    A novel non-Osanger model focusing on non-linear mechanic and chemo-poroelastic coupling of fluids and solute in porous rocks is developed based on the modern wave theory. Analyzing in 1-D a system of two adjacent rocks with different conditions we obtain two coupled non-linear equations for fluid pressure and solute (salt or pollutants) concentration, evolving under the action of strong stress from one "source" rock towards the other rock. Their solutions allow to identify quick non-linear solitary (Burgers) waves of coupled fluid pressure and solute density, that are different from diffusive or perturbative solutions found in other analyses. The strong transient waves for low permeability porous media, such as clay and shale, are analyzed in detail. For medium and high-permeability porous media (sandstones) this model is also tentatively applied. Indeed in recent works of Alexander (1990) and Hart(2009) is supported the presence of small osmotic phenomena in other rocks where osmosis was previously ignored. An attempt to apply our model to soils in Calabria (Italy), such as clastic marine and fluvial deposits as well as discontinuous remnants of Miocene and Pliocene carbonate and terrigeneous deposits, is also discussed.

  11. PASSIVE WIRELESS MULTI-SENSOR TEMPERATURE AND PRESSURE SENSING SYSTEM USING ACOUSTIC WAVE DEVICES Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes the development of passive surface acoustic wave (SAW) sensors and multi-sensor systems for NASA application to remote wireless sensing of...

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

    Science.gov (United States)

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

    2012-05-01

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

  13. Passive Wireless Multi-Sensor Temperature and Pressure Sensing System Using Acoustic Wave Devices Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes the continued development of passive, orthogonal frequency coded (OFC) surface acoustic wave (SAW) sensors and multi-sensor systems, an...

  14. Space and time structure of helium pulsed surface-wave discharges at intermediate pressures (5-50 Torr)

    Science.gov (United States)

    Hamdan, Ahmad; Valade, Fabrice; Margot, Joëlle; Vidal, François; Matte, Jean-Pierre

    2017-01-01

    In this paper, the ignition and development of a plasma created by pulsed surface wave discharges (PSWDs) was experimentally investigated using time-resolved imaging techniques and optical spectroscopy in helium at intermediate gas pressures between 5 and 50 Torr. We found that the ionization front moves at a few km s-1 during the ignition phase and decreases to hundreds of m s-1 after only some tens of µs. Once the plasma has reached a sufficient length, a standing wave pattern is observed in the light emission of the discharge. We attribute its formation to the reflection of the surface wave on the ionization front, which results in a pattern of nodes and antinodes. We have also determined the time and space evolution of the gas temperature. It is shown that the gas temperature increases from the room temperature value to a plateau at several hundreds of degrees over a short time (typically 100 µs). These results supports those obtained by light emission imaging and also show that the standing wave pattern does not affect the gas temperature.

  15. Pulse wave myelopathy: An update of an hypothesis highlighting the similarities between syringomyelia and normal pressure hydrocephalus.

    Science.gov (United States)

    Bateman, Grant A

    2015-12-01

    Most hypotheses trying to explain the pathophysiology of idiopathic syringomyelia involve mechanisms whereby CSF is pumped against a pressure gradient, from the subarachnoid space into the cord parenchyma. On review, these theories have universally failed to explain the disease process. A few papers have suggested that the syrinx fluid may originate from the cord capillary bed itself. However, in these papers, the fluid is said to accumulate due to impaired fluid drainage out of the cord. Again, there is little evidence to substantiate this. This proffered hypothesis looks at the problem from the perspective that syringomyelia and normal pressure hydrocephalus are almost identical in their manifestations but only differ in their site of effect within the neuraxis. It is suggested that the primary trigger for syringomyelia is a reduction in the compliance of the veins draining the spinal cord. This reduces the efficiency of the pulse wave dampening, occurring within the cord parenchyma, increasing arteriolar and capillary pulse pressure. The increased capillary pulse pressure opens the blood-spinal cord barrier due to a direct effect upon the wall integrity and interstitial fluid accumulates due to an increased secretion rate. An increase in arteriolar pulse pressure increases the kinetic energy within the cord parenchyma and this disrupts the cytoarchitecture allowing the fluid to accumulate into small cystic regions in the cord. With time the cystic regions coalesce to form one large cavity which continues to increase in size due to the ongoing interstitial fluid secretion and the hyperdynamic cord vasculature.

  16. Pulse Wave Velocity as Marker of Preclinical Arterial Disease: Reference Levels in a Uruguayan Population Considering Wave Detection Algorithms, Path Lengths, Aging, and Blood Pressure

    Directory of Open Access Journals (Sweden)

    Ignacio Farro

    2012-01-01

    Full Text Available Carotid-femoral pulse wave velocity (PWV has emerged as the gold standard for non-invasive evaluation of aortic stiffness; absence of standardized methodologies of study and lack of normal and reference values have limited a wider clinical implementation. This work was carried out in a Uruguayan (South American population in order to characterize normal, reference, and threshold levels of PWV considering normal age-related changes in PWV and the prevailing blood pressure level during the study. A conservative approach was used, and we excluded symptomatic subjects; subjects with history of cardiovascular (CV disease, diabetes mellitus or renal failure; subjects with traditional CV risk factors (other than age and gender; asymptomatic subjects with atherosclerotic plaques in carotid arteries; patients taking anti-hypertensives or lipid-lowering medications. The included subjects (n=429 were categorized according to the age decade and the blood pressure levels (at study time. All subjects represented the “reference population”; the group of subjects with optimal/normal blood pressures levels at study time represented the “normal population.” Results. Normal and reference PWV levels were obtained. Differences in PWV levels and aging-associated changes were obtained. The obtained data could be used to define vascular aging and abnormal or disease-related arterial changes.

  17. Determination of the elastic wave velocities in porous rocks with the change of overburden pressure and its universal significance

    Institute of Scientific and Technical Information of China (English)

    史謌; 杨东全

    2002-01-01

    Typical rock samples with different lithologic characteristics were collected from exploring wells drilled in sandstone-conglomerate sedimental reservoirs with positive rhythm. In different pore fluid states (fully saturated with gas, water and oil), the velocities of compressional and shear waves (Vp, Vs) were measured under different overburden pressure in laboratory. The effects of pore fluid and different fluid types on the velocities were analyzed. The velocities (Vp, Vs) of the samples fully saturated with water were calculated by use of Gassmann's formula that is suitable for low frequency. The calculated values were compared with the experimental values obtained at high frequency. The result shows that Gassmann's theory can be used to calculate elastic wave velocities in porous rocks saturated with fluid. By this result, the change of elastic velocities with the change of fluid can be predicted. The error is allowable in petroleum engineering. This conclusion is useful for sonic logging interpretation and seismic datum processing.

  18. Multidimensional Hall magnetohydrodynamics with isotropic or anisotropic thermal pressure: numerical scheme and its validation using solitary waves

    CERN Document Server

    Strumik, Marek

    2016-01-01

    We present a numerical solver for plasma dynamics simulations in Hall magnetohydrodynamic (HMHD) approximation in one, two and three dimensions. We consider both isotropic and anisotropic thermal pressure cases, where a general gyrotropic approximation is used. Both explicit energy conservation equation and general polytropic state equations are considered. The numerical scheme incorporates second-order Runge-Kutta advancing in time and Kurganov-Tadmor scheme with van Leer flux limiter for the approximation of fluxes. A flux-interpolated constrained-transport approach is used to preserve solenoidal magnetic field in the simulations. The implemented code is validated using several test problems previously described in the literature. Additionally, we propose a new validation method for HMHD codes based on solitary waves that provides a possibility of quantitative rigorous testing in nonlinear (large amplitude) regime as an extension to standard tests using small-amplitude whistler waves. Quantitative tests of ...

  19. The Application of Erosive Burning to Propellant Charge Interior Ballistics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-lin

    2009-01-01

    Erosive burning is a common burning phenomenon of the gunpowder with inner holes. The actual combustion law of the gunpowder with inner holes can be changed by erosive burning. Pressure difference between the inner and the outer of hole caused by loading density variation of the propellant charge makes erosive burning occur at inner holes during in-bore burning. The effect of erosive burning on burning speed of the propellant is studied by using the effects of flow rate, heat transfer and erosion of the combustion gas in inner holes on burning rate. The mathematic model of erosive burning of the propellant is established. The effects of the factors such as loading density, inner hole size and grain length on erosive burning and interior ballistic performance are analyzed .The method to improve the bore pressure for small charge mass and small firing range by erosive burning is proposed.

  20. Tracking Ocean Gravity Waves in Real-time: Highlights of Bottom Pressure Data Recorded on Ocean Networks Canada's NEPTUNE observatory

    Science.gov (United States)

    Heesemann, Martin; Mihaly, Steve; Gemmrich, Johannes; Davis, Earl; Thomson, Richard; Dewey, Richard

    2016-04-01

    Ocean Networks Canada operates two cabled ocean observatories off Vancouver Island on Canada's west coast. The regional NEPTUNE observatory spans the entire Juan de Fuca tectonic plate from the coast across the subduction zone to the hydrothermally active Endeavour Segment of the Juan de Fuca Ridge Segment while the VENUS observatory focuses on coastal processes. Both observatories collect data on physical, chemical, biological, and geological aspects of the ocean over long time periods, supporting research on complex earth processes. High-precision bottom pressure recorders (BPR) deployed on the NEPTUNE observatory are capable of detecting a wide range of phenomena related to sea level variations. The observatory BPRs provide observations of nano-resolution (with respect to full scale of the instrument) pressure variations which correspond to sub-millimeter scale surface water displacements in several kilometers of water. Detected signals include tides, tsunamis, infragravity waves, swell, wave-induced microseisms, storm surge, and seismic signals. Spectral analysis reveals many of these phenomena with periods ranging from a few seconds to many hours. Dispersion patterns from distant swells are prominent in the swell and microseism bands. By comparing the difference of arrival times between longer period waves, which arrive first, and shorter period waves we can estimate the distance the swells travelled since they were generated. Using this information, swell can be tracked back to specific storms across the Pacific. The presentation will high-light some examples of the mentioned phenomena in the continuous time-series that in some instances are more than seven years long.

  1. Signal-Pressure Curves of Cascaded Four-Wave Mixing in Gas-Filled Capillary by fs Pulses

    Institute of Scientific and Technical Information of China (English)

    CHEN Bao-Zhen; HUANG Zu-Qia

    2005-01-01

    The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and Phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.

  2. Hazard map for volcanic ballistic impacts at Popocatépetl volcano (Mexico)

    Science.gov (United States)

    Alatorre-Ibargüengoitia, Miguel A.; Delgado-Granados, Hugo; Dingwell, Donald B.

    2012-11-01

    During volcanic explosions, volcanic ballistic projectiles (VBP) are frequently ejected. These projectiles represent a threat to people, infrastructure, vegetation, and aircraft due to their high temperatures and impact velocities. In order to protect people adequately, it is necessary to delimit the projectiles' maximum range within well-defined explosion scenarios likely to occur in a particular volcano. In this study, a general methodology to delimit the hazard zones for VBP during volcanic eruptions is applied to Popocatépetl volcano. Three explosion scenarios with different intensities have been defined based on the past activity of the volcano and parameterized by considering the maximum kinetic energy associated with VBP ejected during previous eruptions. A ballistic model is used to reconstruct the "launching" kinetic energy of VBP observed in the field. In the case of Vulcanian eruptions, the most common type of activity at Popocatépetl, the ballistic model was used in concert with an eruptive model to correlate ballistic range with initial pressure and gas content, parameters that can be estimated by monitoring techniques. The results are validated with field data and video observations of different Vulcanian eruptions at Popocatépetl. For each scenario, the ballistic model is used to calculate the maximum range of VBP under optimum "launching" conditions: ballistic diameter, ejection angle, topography, and wind velocity. Our results are presented in the form of a VBP hazard map with topographic profiles that depict the likely maximum ranges of VBP under explosion scenarios defined specifically for Popocatépetl volcano. The hazard zones shown on the map allow the responsible authorities to plan the definition and mitigation of restricted areas during volcanic crises.

  3. Shock wave velocity measurement in the Al2O3 under ultrahigh pressure

    Institute of Scientific and Technical Information of China (English)

    Wang Feng; Peng Xiao-Shi; Liu Shen-Ye; Li Yong-Sheng; Jiang Xiao-Hua; Ding Yong-Kun

    2011-01-01

    In indirect-drive experiment, the blank effect caused by X-rays from Hohlraum will show the dark area in time scale of optical streak camera (OSC). This blank effect, which was a serious problem in indirect-drive shock wave experiments,has been explained by the semiconductor model. The X-rays cause the band to band transition and the probe laser is absorbed by the intraband transition, which leads to a dark region in time scale of the OSC image. In the experiment,the refiectivity of shock wave front was measured to be about 50% at shock wave velocity 32 km/s and was compared to the theoretical calculations with the Drude free electron model. From the experimental data, it is found that the blank effect can be avoided at radiation temperature of 170 eV if the Al layer is thicker than 60 μm.

  4. Modeling and experiments with low-frequency pressure wave propagation in liquid-filled, flexible tubes

    DEFF Research Database (Denmark)

    Bjelland, C; Bjarnø, Leif

    1992-01-01

    A model for wave propagation in a liquid-filled viscoelastic tube with arrays of receivers inside, is being used to analyze the influence of noise generated by in-line vibrational noise sources. In this model, distensibility is of greater importance than compressibility of the liquid....... The dispersion and attenuation is shown to be strongly dependent on the viscoelastic properties of the tube wall. The complex, frequency-dependent moduli of relevant tube materials have been measured in stress wave transfer function experiments. The moduli are used in the model to produce realistic dispersion...... relations and frequency-dependent attenuation. A 12-m-long, liquid-filled tube with interior stress members and connectors in each end is hanging vertically from an upper fixture. The lower end connector is excited by a power vibrator to generate the relevant wave modes. Measurements with reference...

  5. Ballistic Response of Fabrics: Model and Experiments

    Science.gov (United States)

    Orphal, Dennis L.; Walker Anderson, James D., Jr.

    2001-06-01

    Walker (1999)developed an analytical model for the dynamic response of fabrics to ballistic impact. From this model the force, F, applied to the projectile by the fabric is derived to be F = 8/9 (ET*)h^3/R^2, where E is the Young's modulus of the fabric, T* is the "effective thickness" of the fabric and equal to the ratio of the areal density of the fabric to the fiber density, h is the displacement of the fabric on the axis of impact and R is the radius of the fabric deformation or "bulge". Ballistic tests against Zylon^TM fabric have been performed to measure h and R as a function of time. The results of these experiments are presented and analyzed in the context of the Walker model. Walker (1999), Proceedings of the 18th International Symposium on Ballistics, pp. 1231.

  6. Digital Array Radar for Ballistic Missile Defense and Counter-Stealth Systems Analysis and Parameter Tradeoff Study

    Science.gov (United States)

    2006-09-14

    Missile BMD Ballistic Missile Defense CAS Computer Algebra System CDD Capability Development Document CONOPS Concept of Operations CONUS Continental...this section. Analysis and calculations described in this section were conducted using Waterloo Maple® 7 Computer Algebra System (CAS). Initially...When two or more electromagnetic waves combine, their electric fields are integrated vectorially at each point in space for any

  7. Numerical survey of pressure wave propagation around and inside an underground cavity with high order FEM

    Science.gov (United States)

    Esterhazy, Sofi; Schneider, Felix; Schöberl, Joachim; Perugia, Ilaria; Bokelmann, Götz

    2016-04-01

    The research on purely numerical methods for modeling seismic waves has been more and more intensified over last decades. This development is mainly driven by the fact that on the one hand for subsurface models of interest in exploration and global seismology exact analytic solutions do not exist, but, on the other hand, retrieving full seismic waveforms is important to get insides into spectral characteristics and for the interpretation of seismic phases and amplitudes. Furthermore, the computational potential has dramatically increased in the recent past such that it became worthwhile to perform computations for large-scale problems as those arising in the field of computational seismology. Algorithms based on the Finite Element Method (FEM) are becoming increasingly popular for the propagation of acoustic and elastic waves in geophysical models as they provide more geometrical flexibility in terms of complexity as well as heterogeneity of the materials. In particular, we want to demonstrate the benefit of high-order FEMs as they also provide a better control on the accuracy. Our computations are done with the parallel Finite Element Library NGSOLVE ontop of the automatic 2D/3D mesh generator NETGEN (http://sourceforge.net/projects/ngsolve/). Further we are interested in the generation of synthetic seismograms including direct, refracted and converted waves in correlation to the presence of an underground cavity and the detailed simulation of the comprehensive wave field inside and around such a cavity that would have been created by a nuclear explosion. The motivation of this application comes from the need to find evidence of a nuclear test as they are forbidden by the Comprehensive Nuclear-Test Ban Treaty (CTBT). With this approach it is possible for us to investigate the wave field over a large bandwidth of wave numbers. This again will help to provide a better understanding on the characteristic signatures of an underground cavity, improve the protocols for

  8. Study of atmospheric gravity waves and infrasonic sources using the USArray Transportable Array pressure data

    Science.gov (United States)

    Hedlin, Michael; de Groot-Hedlin, Catherine; Hoffmann, Lars; Alexander, M. Joan; Stephan, Claudia

    2016-04-01

    The upgrade of the USArray Transportable Array (TA) with microbarometers and infrasound microphones has created an opportunity for a broad range of new studies of atmospheric sources and the large- and small-scale atmospheric structure through which signals from these events propagate. These studies are akin to early studies of seismic events and the Earth's interior structure that were made possible by the first seismic networks. In one early study with the new dataset we use the method of de Groot-Hedlin and Hedlin (2015) to recast the TA as a massive collection of 3-element arrays to detect and locate large infrasonic events. Over 2,000 events have been detected in 2013. The events cluster in highly active regions on land and offshore. Stratospherically ducted signals from some of these events have been recorded more than 2,000 km from the source and clearly show dispersion due to propagation through atmospheric gravity waves. Modeling of these signals has been used to test statistical models of atmospheric gravity waves. The network is also useful for making direct observations of gravity waves. We are currently studying TA and satellite observations of gravity waves from singular events to better understand how the waves near ground level relate to those observed aloft. We are also studying the long-term statistics of these waves from the beginning of 2010 through 2014. Early work using data bandpass filtered from 1-6 hr shows that both the TA and satellite data reveal highly active source regions, such as near the Great Lakes. de Groot-Hedlin and Hedlin, 2015, A method for detecting and locating geophysical events using clusters of arrays, Geophysical Journal International, v203, p960-971, doi: 10.1093/gji/ggv345.

  9. Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

    Science.gov (United States)

    Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.; Wygant, J. R.

    2017-01-01

    Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. Here on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration with the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.

  10. Consolidation and dynamics of 3D unsaturated porous seabed under rigid caisson breakwater loaded by hydrostatic pressure and wave

    Institute of Scientific and Technical Information of China (English)

    YE JianHong; JENG DongSheng; CHAN A H C

    2012-01-01

    In this study,based on the dynamic Biot's theory "u-p" approximation,a 3D finite element method (FEM) numerical soil model is developed,in which the Generalized Newmark-β method is adopted to determine the time integration.The developed 3D FEM soil model is a part of the coupled model PORO-WSSI 3D for 3D wave-seabed-marine structures interaction problem,and is validated by the analytical solution proposed by Wang (2000) for a laterally infinite seabed loaded by a uniform force.By adopting the developed 3D soil model,the consolidation of seabed under a caisson breakwater and hydrostatic pressure is investigated.The numerical results show that the caisson breakwater built on seabed has very significant effect on the stresses/displacements fields in the seabed foundation after the transient deformation and primary consolidation are completed.The parametric study indicates that the Young's modulus E of seabed is the most important parameter to affect the settlement of breakwater,and the displacement fields in seabed foundation.Taking the consolidation status as the initial condition,the interaction between ocean wave,caisson breakwater and seabed foundation is briefly investigated.The 3D ocean wave is determined by solving the Navier-Stokes equations with finite volume method (FVM).The numerical results indicate that there is intensive interaction between ocean wave,caisson breakwater and seabed foundation; and the breakwater indeed can effectively block the wave energy propagating to the coastline.

  11. Small unmanned aircraft ballistic impact speed

    DEFF Research Database (Denmark)

    La Cour-Harbo, Anders

    2018-01-01

    A study of how smaller unmanned aircraft will fall in case of failure. The aim is to determine the impact speed of a drone givens its general shape and aerodynamic behavior. This will include both CFD simulations and real world test of ballistic drops of smaller drones.......A study of how smaller unmanned aircraft will fall in case of failure. The aim is to determine the impact speed of a drone givens its general shape and aerodynamic behavior. This will include both CFD simulations and real world test of ballistic drops of smaller drones....

  12. Pressure dependence of the optical properties of the charge-density-wave compound LaTe2

    Energy Technology Data Exchange (ETDEWEB)

    Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; /Zurich, ETH; Arcangeletti, E.; Baldassarre, L.; Postorino, P.; Lupi, S.; /Rome U.; Perucchi, A.; /INFM, Trieste; Shin, K.Y.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2009-12-14

    We report the pressure dependence of the optical response of LaTe{sub 2}, which is deep in the charge-density-wave (CDW) ground state even at 300 K. The reflectivity spectrum is collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 7 GPa. We extract the energy scale due to the single particle excitation across the CDW gap and the Drude weight. We establish that the gap decreases upon compressing the lattice, while the Drude weight increases. This signals a reduction in the quality of nesting upon applying pressure, therefore inducing a lesser impact of the CDW condensate on the electronic properties of LaTe{sub 2}. The consequent suppression of the CDW gap leads to a release of additional charge carriers, manifested by the shift of weight from the gap feature into the metallic component of the optical response. On the contrary, the power-law behavior, seen in the optical conductivity at energies above the gap excitation and indicating a weakly interacting limit within the Tomonaga-Luttinger liquid scenario, seems to be only moderately dependent on pressure.

  13. Pressure-induced forces and shear stresses on rubble mound breakwater armour layers in regular waves

    DEFF Research Database (Denmark)

    Jensen, Bjarne; Christensen, Erik Damgaard; Sumer, B. Mutlu

    2014-01-01

    measurements in the core material: (1) core material with an idealized armour layer made out of spherical objects that also allowed for detailed velocity measurements between and above the armour, and (2) core material with real rock armour stones. The same core material was applied through the entire......This paper presents the results from an experimental investigation of the pressure-induced forces in the core material below the main armour layer and shear stresses on the armour layer for a porous breakwater structure. Two parallel experiments were performed which both involved pore pressure...... pressure gradients were found which exerted a lift force up to ≈60% of the submerged weight of the core material. These maximum outward directed pressure gradients were linked to the maximum run-down event and were in general situated at, or slightly below, the maximum run-down level. Detailed velocity...

  14. Workbook for predicting pressure wave and fragment effects of exploding propellant tanks and gas storage vessels

    Science.gov (United States)

    Baker, W. E.; Kulesz, J. J.; Ricker, R. E.; Bessey, R. L.; Westine, P. S.; Parr, V. B.; Oldham, G. A.

    1975-01-01

    Technology needed to predict damage and hazards from explosions of propellant tanks and bursts of pressure vessels, both near and far from these explosions is introduced. Data are summarized in graphs, tables, and nomographs.

  15. Nonlinear Acoustics in a Dispersive Continuum: Random Waves, Radiation Pressure, and Quantum Noise.

    Science.gov (United States)

    1983-03-01

    Karpman , Nonlinear Waves in Dispersive Media, Pergamon Press, New York, 1975, p. 76. 26. R. Beyers, Nonlinear Acoustics, U.S. Government Printing...20301 U. S. Army Research nffice 2 copies Box 12211 Research Triangle Park tlorth Carolina 27709 Defense Technical Information Center 12 copies Cameron

  16. Does wave reflection explain the increase in blood pressure during leg crossing?

    NARCIS (Netherlands)

    Velthoven, M.H. van; Holewijn, S.; Wilt, G.J. van der; Thien, Th.; Deinum, J.

    2014-01-01

    OBJECTIVE: To assess the effect of crossing legs at the knee level on wave reflection, as measured by the augmentation index. METHODS: Forty-two participants crossed their legs at the knee level (popliteal fossa over the suprapatellar bursa) in the sitting position for 12 min. One trained investigat

  17. Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 2: Mechanisms for the pathogenesis of syringomyelia.

    Science.gov (United States)

    Carpenter, P W; Berkouk, K; Lucey, A D

    2003-12-01

    Our aim in this paper is to use a simple theoretical model of the intraspinal cerebrospinal-fluid system to investigate mechanisms proposed for the pathogenesis of syringomyelia. The model is based on an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. According to this model, the leading edge of a pressure pulse tends to steepen and form an elastic jump, as it propagates up the intraspinal cerebrospinal-fluid system. We show that when an elastic jump is incident on a stenosis of the spinal subarachnoid space, it reflects to form a transient, localized region of high pressure within the spinal cord that for a cough-induced pulse is estimated to be 50 to 70 mm Hg or more above the normal level in the spinal subarachnoid space. We propose this as a new mechanism whereby pressure pulses created by coughing or sneezing can generate syrinxes. We also use the same analysis to investigate Williams' suck mechanism. Our results do not support his concept, nor, in cases where the stenosis is severe, the differential-pressure-propagation mechanism recently proposed by Greitz et al. Our analysis does provide some support for the piston mechanism recently proposed by Oldfield et al. and Heiss et al. For instance, it shows clearly how the spinal cord is compressed by the formation of elastic jumps over part of the cardiac cycle. What appears to be absent for this piston mechanism is any means whereby the elastic jumps can be focused (e.g., by reflecting from a stenosis) to form a transient, localized region of high pressure within the spinal cord. Thus it would seem to offer a mechanism for syrinx progression, but not for its formation.

  18. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many t...

  19. Enhancement of Transdermal Drug Delivery by ns Q-swithed Nd:YAG Laser-induced Pressure Wave

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A non-invasive laser enhancing transdermal drug delivery technique has been investigated. The second harmonic wavelength of 532 nm of a Q-Switched Nd:YAG laser with pulse duration of 15 ns was used to irradiate on a black polyethylene sheet covering on the surface of the drug solution, and hence produced pressure waves in the solution. Porcine skin and Rhodamine B were used as skin model and reagent respectively.Fluorescence microscope was employed to examine the mechanisms of drug delivery via the skin samples after laser treatment. The experiment revealed that the penetration depth of Rhodamine B under the illumination of laser increased with the energy density of the laser beam. After 20 laser shots at laser energy density of 70 mJ/cm2, the penetration depth reached 440 μm in 30 minutes, which was about three times as that without laser illumination. One possible explanation was that laser-induced pressure waves formed microchannels in the stratum corneum of the skin tissue. These microchannels provided much more effective paths for infiltration of Rhodamine B through the SC than follicular and intercellular paths. The drug solution diffused into the SC under the concentration gradient through the channels.

  20. Black Tea Lowers Blood Pressure and Wave Reflections in Fasted and Postprandial Conditions in Hypertensive Patients: A Randomised Study

    Directory of Open Access Journals (Sweden)

    Davide Grassi

    2015-02-01

    Full Text Available Hypertension and arterial stiffening are independent predictors of cardiovascular mortality. Flavonoids may exert some vascular protection. We investigated the effects of black tea on blood pressure (BP and wave reflections before and after fat load in hypertensives. According to a randomized, double-blind, controlled, cross-over design, 19 patients were assigned to consume black tea (129 mg flavonoids or placebo twice a day for eight days (13 day wash-out period. Digital volume pulse and BP were measured before and 1, 2, 3 and 4 h after tea consumption. Measurements were performed in a fasted state and after a fat load. Compared to placebo, reflection index and stiffness index decreased after tea consumption (p < 0.0001. Fat challenge increased wave reflection, which was counteracted by tea consumption (p < 0.0001. Black tea decreased systolic and diastolic BP (−3.2 mmHg, p < 0.005 and −2.6 mmHg, p < 0.0001; respectively and prevented BP increase after a fat load (p < 0.0001. Black tea consumption lowers wave reflections and BP in the fasting state, and during the challenging haemodynamic conditions after a fat load in hypertensives. Considering lipemia-induced impairment of arterial function may occur frequently during the day, our findings suggest regular consumption of black tea may be relevant for cardiovascular protection.

  1. Effects of weak periodic pressure waves on time to ignition of fuel mixtures

    Science.gov (United States)

    Vainshtein, P.; Gutfinger, C.

    2001-09-01

    The accumulation of small-amplitude gas dynamic perturbations accelerates the process of self-ignition of a homogeneous explosive mixture. In the present paper the cumulative effect of forced acoustic oscillations is studied when timescales of piston motions in a closed cylinder are comparable with the acoustic timescale. It is shown that the most significant shortening of the time to ignition takes place in a resonant system, where periodic shock waves travel back and forth in the cylinder.

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

    OpenAIRE

    Sochet, Isabelle; Sauvan, Pierre-Emmanuel; Trelat, Sophie

    2012-01-01

    International audience; To understand the blast effects of confined explosions, it is necessary to study the characteristic parameters of the blast wave in terms of overpressure, impulse and arrival time. In a previous study, experiments were performed using two different scales of a pyrotechnic workshop. The main purpose of these experiments was to compare the TNT equivalent for solid and gaseous explosives in terms of mass to define a TNT equivalent in a reflection field and to validate the...

  3. Experimental and numerical characterization of the sound pressure in standing wave acoustic levitators.

    Science.gov (United States)

    Stindt, A; Andrade, M A B; Albrecht, M; Adamowski, J C; Panne, U; Riedel, J

    2014-01-01

    A novel method for predictions of the sound pressure distribution in acoustic levitators is based on a matrix representation of the Rayleigh integral. This method allows for a fast calculation of the acoustic field within the resonator. To make sure that the underlying assumptions and simplifications are justified, this approach was tested by a direct comparison to experimental data. The experimental sound pressure distributions were recorded by high spatially resolved frequency selective microphone scanning. To emphasize the general applicability of the two approaches, the comparative studies were conducted for four different resonator geometries. In all cases, the results show an excellent agreement, demonstrating the accuracy of the matrix method.

  4. Experimental studies of electrical conductivities and P-wave velocities of gabbro at high pressures and high temperatures

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2003-01-01

    The P-wave velocities and electrical conductivities of gabbro were measured using ultrasonic transmission method and impedance spectroscopy from room temperature to 1100℃ at 1-2 GPa, and the factors controlling the P-wave velocity and the microscopic conductance mechanisms of the rock were analyzed. The experimental results show that the P-wave velocities of gabbro drop abruptly at temperatures of 800-850℃ and under pressures of 1-2 GPa due to the occurrence of grain boundary phases and dehydration melting; however, the electrical conductivities and electronic conduction mechanisms have not changed obviously at temperatures of 800-850℃. At temperatures Below 680℃, only one impedance arc (I) corresponding to grain interior conduction occurs at frequencies between 12 Hz and 105 Hz, the second arc (II) corresponding to grain boundary conduction occurs at temperatures above 680℃. The total conductivity of this rock is dominated by the grain interior conductivity as the occurrence of grain boundary conduction has a small effect on the total conductivity. The laboratory-measured velocities are consistent with the average P-wave velocity observations of lower crust and upper mantle. The conductivity values correspond well with the gabbroite composition of the lower crust and upper mantle; however, they are about 1-2 orders of magnitude lower than MT data from the high conductive layers. The experiments confirm that the dehydration of hydrous minerals can induce the partial melting, and the low seismic velocity zones might be correlated with the high conductive layers if partial melting occurs.

  5. Graphene Triangular Ballistic Rectifier: Fabrication and Characterisation

    Science.gov (United States)

    Auton, Gregory; Kumar, Roshan Krishna; Hill, Ernie; Song, Aimin

    2016-09-01

    It has been shown that graphene can demonstrate ballistic transport at room temperature. This opens up a range of practical applications that do not require graphene to have a band gap, which is one of the most significant challenges for its use in the electronics industry. Here, the very latest high mobility graphene (>100,000 cm2 V-1 s-1) fabrication techniques will be demonstrated so that one such device, called the triangular ballistic rectifier (TBR), can be characterised. The TBR is a four-terminal device with a triangular anti-dot at their intersection; two sides of the triangle are positioned and angled such that ballistic carriers from the two input electrodes are redirected like billiard balls to one of the two output contacts irrespective of the instantaneous polarity of the input. A responsivity of 2400 mV mW-1 is demonstrated at room temperature from a low-frequency input signal. The ballistic nature of the device is justified and explained in more detail with low-temperature measurements.

  6. First Soviet Sea-Launched Ballistic Rockets

    Directory of Open Access Journals (Sweden)

    Yuri F. Katorin

    2013-03-01

    Full Text Available In the article it is told about the creation of the first generation of Soviet ballistic missiles for the armament of submarines. The basic stages of their development, tests and adoption for the armament are described. Are cited the data about the people, is most which actively participated in these processes.

  7. The Ballistic Cart on an Incline Revisited.

    Science.gov (United States)

    Serway, Raymond A.; And Others

    1995-01-01

    Presents the theory behind the mechanics demonstration that involves projecting a ball vertically upward from a ballistic cart moving along an inclined plane. The measured overshoot is believed to be due, in part, to the presence of rolling friction and the inertial properties of the cart wheels. (JRH)

  8. The Internal Ballistics of an Air Gun

    Science.gov (United States)

    Denny, Mark

    2011-01-01

    The internal ballistics of a firearm or artillery piece considers the pellet, bullet, or shell motion while it is still inside the barrel. In general, deriving the muzzle speed of a gunpowder firearm from first principles is difficult because powder combustion is fast and it very rapidly raises the temperature of gas (generated by gunpowder…

  9. Electron Interference in Ballistic Graphene Nanoconstrictions

    DEFF Research Database (Denmark)

    Baringhaus, Jens; Settnes, Mikkel; Aprojanz, Johannes

    2016-01-01

    We realize nanometer size constrictions in ballistic graphene nanoribbons grown on sidewalls of SiC mesa structures. The high quality of our devices allows the observation of a number of electronic quantum interference phenomena. The transmissions of Fabry-Perot-like resonances are probed...

  10. Characteristics of pressure wave in common rail fuel injection system of high-speed direct injection diesel engines

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Herfatmanesh

    2016-05-01

    Full Text Available The latest generation of high-pressure common rail equipment now provides diesel engines possibility to apply as many as eight separate injection pulses within the engine cycle for reducing emissions and for smoothing combustion. With these complicated injection arrangements, optimizations of operating parameters for various driving conditions are considerably difficult, particularly when integrating fuel injection parameters with other operating parameters such as exhaust gas recirculation rate and boost pressure together for evaluating calibration results. Understanding the detailed effects of fuel injection parameters upon combustion characteristics and emission formation is therefore particularly critical. In this article, the results and discussion of experimental investigations on a high-speed direct injection light-duty diesel engine test bed are presented for evaluating and analyzing the effects of main adjustable parameters of the fuel injection system on all regulated emission gases and torque performance. Main injection timing, rail pressure, pilot amount, and particularly pilot timing have been examined. The results show that optimization of each of those adjustable parameters is beneficial for emission reduction and torque improvement under different operating conditions. By exploring the variation in the interval between the pilot injection and the main injection, it is found that the pressure wave in the common rail has a significant influence on the subsequent injection. This suggests that special attentions must be paid for adjusting pilot timing or any injection interval when multi-injection is used. With analyzing the fuel amount oscillation of the subsequent injections to pilot separation, it demonstrates that the frequency of regular oscillations of the actual fuel amount or the injection pulse width with the variation in pilot separation is always the same for a specified fuel injection system, regardless of engine speed

  11. Principles of ballistics applicable to the treatment of gunshot wounds.

    Science.gov (United States)

    Swan, K G; Swan, R C

    1991-04-01

    Ballistics is the science of the motion of a projectile through the barrel of a firearm (internal ballistics), during its subsequent flight (external ballistics), and during its final complicated motion after it strikes a target (terminal ballistics). Wound ballistics is a special case of terminal ballistics. Although wound ballistics is at best sets of approximations, its principles enter usefully into an evaluation of a gunshot wound and its treatment. A special consideration in these cases is their medicolegal aspects. At a minimum, the medical team receiving the patient should exert care not to destroy the clothing and in particular to cut around and not through bullet holes, to turn over to law enforcement officials any metallic foreign body recovered from the patient, and to describe precisely, or even to photograph, any entrance or exit wounds.

  12. Ballistic evaluationof LOVA propellant in high calibre gun

    Directory of Open Access Journals (Sweden)

    A.G.S. Pillai

    2001-04-01

    Full Text Available 'This paper presents the data obrained on dynamic firing of a cellulose acetate binder-based low vulnerability ammunition (LOV A propellant using 120 mm fin-stabilised armour piercing discarding sabot (FSAPDS kinetic energyammunition. An optimised propellant composition formulated ~sing fine RDX as an energetic ingredient and a mixture of cellulose acetate and nitrocellulose as binder was qualified fit for firing in a high calibre gun by its successful static evaluation for absolute ballistics using high pressure closed vessel technique. Dynamic firing of the propellant processed in heptatubular geometry was undertaken to assess the propellant charge mass. This propellant achieved higher muzzle velocity as compared to the standard NQ/M119 triple-base propellant while meeting the non-vulnerability characteristics convincingly.

  13. A boundary integral approach to analyze the viscous scattering of a pressure wave by a rigid body

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N.

    2008-01-01

    The paper provides boundary integral equations for solving the problem of viscous scattering of a pressure wave by a rigid body. By using this mathematical tool uniqueness and existence theorems are proved. Since the boundary conditions are written in terms of velocities, vector boundary integral equations are obtained for solving the problem. The paper introduces single-layer viscous potentials and also a stress tensor. Correspondingly, a viscous double-layer potential is defined. The properties of all these potentials are investigated. By representing the scattered field as a combination of a single-layer viscous potential and a double-layer viscous potential the problem is reduced to the solution of a singular vectorial integral equation of Fredholm type of the second kind. In the case where the stress vector on the boundary is the main quantity of interest the corresponding boundary singular integral equation is proved to have a unique solution. PMID:18709178

  14. Influence of viscosity on the scattering of an air pressure wave by a rigid body: a regular boundary integral formulation

    Science.gov (United States)

    Homentcovschi, Dorel

    2008-01-01

    This paper gives a regular vector boundary integral equation for solving the problem of viscous scattering of a pressure wave by a rigid body. Firstly, single-layer viscous potentials and a generalized stress tensor are introduced. Correspondingly, generalized viscous double-layer potentials are defined. By representing the scattered field as a combination of a single-layer viscous potential and a generalized viscous double-layer potential, the problem is reduced to the solution of a vectorial Fredholm integral equation of the second kind. Generally, the vector integral equation is singular. However, there is a particular stress tensor, called pseudostress, which yields a regular integral equation. In this case, the Fredholm alternative applies and permits a direct proof of the existence and uniqueness of the solution. The results presented here provide the foundation for a numerical solution procedure. PMID:19865494

  15. Experimental study of propagation characteristics of a pulse-modulated surface-wave argon plasma at atmospheric pressure

    Science.gov (United States)

    Chen, Chuan-Jie; Li, Shou-Zhe; Wu, Yue; Li, Zhen-Ye; Zhang, Jialiang; Wang, Yong-Xing

    2016-12-01

    An atmospheric-pressure, pulse-modulated surface wave argon plasma is investigated with respect to its propagation of the ionization front. The time-resolved photographs about the advance of the ionization front are taken using a high speed camera. The ionization front velocity and its rise time when propagating along the discharge tube are measured with respect to a series of values of input power, duty ratio, and the pulse repetition frequency. The interpretations are given on the basis of the ionization and diffusion processes. And it is also found that the reduced electric field and memory effect from previous discharge impose the influence on both the ionization front velocity and its rise time strongly.

  16. Measurement of high-pressure shock waves in cryogenic deuterium-tritium ice layered capsule implosions on NIF.

    Science.gov (United States)

    Robey, H F; Moody, J D; Celliers, P M; Ross, J S; Ralph, J; Le Pape, S; Berzak Hopkins, L; Parham, T; Sater, J; Mapoles, E R; Holunga, D M; Walters, C F; Haid, B J; Kozioziemski, B J; Dylla-Spears, R J; Krauter, K G; Frieders, G; Ross, G; Bowers, M W; Strozzi, D J; Yoxall, B E; Hamza, A V; Dzenitis, B; Bhandarkar, S D; Young, B; Van Wonterghem, B M; Atherton, L J; Landen, O L; Edwards, M J; Boehly, T R

    2013-08-09

    The first measurements of multiple, high-pressure shock waves in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these shocks must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of shock timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique.

  17. Multidimensional Hall magnetohydrodynamics with isotropic or anisotropic thermal pressure: Numerical scheme and its validation using solitary waves

    Science.gov (United States)

    Strumik, Marek; Stasiewicz, Krzysztof

    2017-02-01

    We present a numerical solver for plasma dynamics simulations in Hall magnetohydrodynamic (HMHD) approximation in one, two and three dimensions. We consider both isotropic and anisotropic thermal pressure cases, where a general gyrotropic approximation is used. Both explicit energy conservation equation and general polytropic state equations are considered. The numerical scheme incorporates second-order Runge-Kutta advancing in time and Kurganov-Tadmor scheme with van Leer flux limiter for the approximation of fluxes. A flux-interpolated constrained-transport approach is used to preserve solenoidal magnetic field in the simulations. The implemented code is validated using several test problems previously described in the literature. Additionally, we propose a new validation method for HMHD codes based on solitary waves that provides a possibility of quantitative rigorous testing in nonlinear (large amplitude) regime as an extension to standard tests using small-amplitude whistler waves. Quantitative tests of accuracy and performance of the implemented code show the fidelity of the proposed approach.

  18. Numerical study with experimental comparison of pressure waves in the air intake system of an internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, Carlos E.G.; Vielmo, Horacio A. [Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Mechanical Engineering Dept.], E-mails: vielmoh@mecanica.ufrgs.br; Hanriot, Sergio M. [Pontifical Catholic University of Minas Gerais (PUC-Minas), Belo Horizonte, MG (Brazil). Mechanical Engineering Dept.], E-mail: hanriot@pucminas.br

    2010-07-01

    The work investigates the pressure waves behavior in the intake system of an internal combustion engine. For the purpose of examining this problem, it was chosen an experimental study in order to validate the results of the present simulation. At the literature there are several experimental studies, and some numerical simulations, but the most of the numerical studies treat the problem only in one dimension in practical problems, or two dimensions in specific problems. Using a CFD code it is possible to analyze more complex systems, including tridimensional effects. The pulsating phenomenon is originated from the periodic movement of the intake valve, and produces waves that propagate within the system. The intake system studied was composed by a straight pipe connected to a 1000 cc engine with a single operating cylinder. The experiments were carried out in a flow bench. In the present work, the governing equations was discretized by Finite Volumes Method with an explicit formulation, and the time integration was made using the multi-stage Runge-Kutta time stepping scheme. The solution is independent of mesh or time step. The numerical analysis presents a good agreement with the experimental results. (author)

  19. Black tea lowers blood pressure and wave reflections in fasted and postprandial conditions in hypertensive patients: a randomised study.

    Science.gov (United States)

    Grassi, Davide; Draijer, Richard; Desideri, Giovambattista; Mulder, Theo; Ferri, Claudio

    2015-02-04

    Hypertension and arterial stiffening are independent predictors of cardiovascular mortality. Flavonoids may exert some vascular protection. We investigated the effects of black tea on blood pressure (BP) and wave reflections before and after fat load in hypertensives. According to a randomized, double-blind, controlled, cross-over design, 19 patients were assigned to consume black tea (129 mg flavonoids) or placebo twice a day for eight days (13 day wash-out period). Digital volume pulse and BP were measured before and 1, 2, 3 and 4 h after tea consumption. Measurements were performed in a fasted state and after a fat load. Compared to placebo, reflection index and stiffness index decreased after tea consumption (ptea consumption (pBlack tea decreased systolic and diastolic BP (-3.2 mmHg, pBlack tea consumption lowers wave reflections and BP in the fasting state, and during the challenging haemodynamic conditions after a fat load in hypertensives. Considering lipemia-induced impairment of arterial function may occur frequently during the day, our findings suggest regular consumption of black tea may be relevant for cardiovascular protection.

  20. Fluorescence microscopy beyond the ballistic regime by ultrasound pulse guided digital phase conjugation

    CERN Document Server

    Cui, Meng; Fiolka, Reto

    2012-01-01

    Fluorescence microscopy has revolutionized biomedical research over the past three decades. Its high molecular specificity and unrivaled single molecule level sensitivity have enabled breakthroughs in a variety of research fields. For in vivo applications, its major limitation is the superficial imaging depth as random scattering in biological tissues causes exponential attenuation of the ballistic component of a light wave. Here we present fluorescence microscopy beyond the ballistic regime by combining single cycle pulsed ultrasound modulation and digital optical phase conjugation. We demonstrate near isotropic 3D localized sound-light interaction with an imaging depth as high as thirteen scattering path lengths. With the exceptionally high optical gain provided by the digital optical phase conjugation system, we can deliver sufficient optical power to a focus inside highly scattering media for not only fluorescence microscopy but also a variety of linear and nonlinear spectroscopy measurements. This techno...

  1. Transport measurements of negative refractive behavior in ballistic graphene hetero junctions

    Science.gov (United States)

    Lee, Gil-Ho; Park, Geon-Hyoung; Kim, Minsoo; Lee, Jae Hyeong; Lee, Hu-Jong

    2015-03-01

    We investigated the electronic current refraction at p-n junctions (PNJs) in ballistic monolayer graphene. Given a peculiar band structure of the graphene, the transmission of electrons through a PNJ is predicted to be similar to the optical refraction at the boundary of metamaterials with negative refractive index. In consequence, electrons waves injected at a point in one side of a junction can be refocused into a single point in the other side of the junction, which demonstrates Veselago lensing for the electrons. By adopting high-yield dry-transfer technique, we fabricated fully ballistic graphene devices encapsulated by hexagonal boron nitrides with a local top gate. We will present the signatures of negative refractive transport behavior of electrons in PNJs and also discuss about the electronic current focusing in p-n-p heterojunctions in terms of Veselago lensing.

  2. Ballistic phonon transport through a Fibonacci array of acoustic nanocavities in a narrow constriction

    Energy Technology Data Exchange (ETDEWEB)

    Mo Yuan [Department of Applied Physics, Hunan University, Changsha 410082 (China); Huang Weiqing, E-mail: wqhuang2000@yahoo.co [Department of Applied Physics, Hunan University, Changsha 410082 (China); Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan University, Changsha 410082 (China); CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China); Huang Guifang, E-mail: gfhuang@hnu.edu.c [Department of Applied Physics, Hunan University, Changsha 410082 (China); Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan University, Changsha 410082 (China); Hu Wangyu; Wang Lingling; Pan Anlian [Department of Applied Physics, Hunan University, Changsha 410082 (China); Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan University, Changsha 410082 (China)

    2011-05-09

    We investigate the ballistic phonon transport through a Fibonacci array of acoustic nanocavities in a narrow constriction of a semiconductor nanowire at low temperatures. It is found that the transmission spectrum of such a system consists of quasiband gaps and narrow resonances caused by the coupling of phonon waves. Both phonon transmission and thermal conductance exhibit the similarity due to the Fibonacci sequence structure. The similarity is sensitive to the number n and parameters of nanocavities. The results are compared with those in a periodic acoustic nanocavities. - Highlights: Ballistic phonon transport in a Fibonacci array of acoustic nanocavities is studied. The transmission spectrum consists of quasiband gaps and narrow resonances. Both phonon transmission and thermal conductance exhibit the similarity. The similarity is sensitive to the number and parameters of nanocavities.

  3. Two-wave photon Doppler velocimetry measurements in direct impact Hopkinson pressure bar experiments

    Directory of Open Access Journals (Sweden)

    Lea Lewis J.

    2015-01-01

    Full Text Available Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion and faster achievement of force equilibrium. Currently advantages are gained at a significant cost: the fact that input bar data is unavailable removes all information about the striker impacted specimen face, preventing the determination of force equilibrium, and requiring approximations to be made on the sample deformation history. Recently photon Doppler velocimetry methods have been developed, which can replace strain gauges on Hopkinson bars. In this paper we discuss an experimental method and complementary data analysis for using Doppler velocimetry to measure surface velocities of the striker and output bars in a direct impact bar experiment, allowing similar data to be recorded as in a split bar system, with the same level of convenience. We discuss extracting velocity and force measurements, and improving the accuracy and convenience of Doppler velocimetry on Hopkinson bars. Results obtained using the technique are compared to equivalent split bar tests, showing improved stress measurements for the lowest and highest strains.

  4. Influence of Various Process Parameters on Mechanical Properties and Ballistics of Nitramine-Based Advanced CMDB Propellants

    Directory of Open Access Journals (Sweden)

    S. N. Asthana

    1991-10-01

    Full Text Available This paper reports the influence of important process parameters, namely mixing time and batch size; on the mechanical properties and ballistics of nitramine-based advanced CMDB propellants. Considerable improvement to the tune of 67 per cent in tensile strength was observed at a mixing time increase of 60-135 min. Scaling up of batch size from 8 to 25 kg resulted in 30 per cent higher tensile strength. Recorded enhancement of burning rate was of the order of 8 per cent in both the sets of experiments. Ballistically modified composition revealed 11-12 per cent increase in burning rate at all the pressure ranges, on combined increase in mixing time (55 to 85 min and batch size(5-17kg. These findings are in line with those reported for composite and ballistically modified double-base propellants.

  5. Ballistic model to estimate microsprinkler droplet distribution

    Directory of Open Access Journals (Sweden)

    Conceição Marco Antônio Fonseca

    2003-01-01

    Full Text Available Experimental determination of microsprinkler droplets is difficult and time-consuming. This determination, however, could be achieved using ballistic models. The present study aimed to compare simulated and measured values of microsprinkler droplet diameters. Experimental measurements were made using the flour method, and simulations using a ballistic model adopted by the SIRIAS computational software. Drop diameters quantified in the experiment varied between 0.30 mm and 1.30 mm, while the simulated between 0.28 mm and 1.06 mm. The greatest differences between simulated and measured values were registered at the highest radial distance from the emitter. The model presented a performance classified as excellent for simulating microsprinkler drop distribution.

  6. Ballistic Missile Silo Door Monitoring Analysis

    Energy Technology Data Exchange (ETDEWEB)

    EDENBURN,MICHAEL W.; TROST,LAWRENCE C.

    2000-01-01

    This paper compares the cost and effectiveness of several potential options that may be used to monitor silo-based ballistic missiles. Silo door monitoring can be used to verify that warheads removed to deactivate or download silo-based ballistic missiles have not been replaced. A precedent for monitoring warhead replacement using reentry vehicle on site inspections (RV-OSIs) and using satellites has been established by START-I and START-II. However, other monitoring options have the potential to be less expensive and more effective. Three options are the most promising if high verification confidence is desired: random monitoring using door sensors; random monitoring using manned or unmanned aircraft; and continuous remote monitoring using unattended door sensors.

  7. Ballistic penetration of Perma-Gel

    Science.gov (United States)

    Ryckman, Raymond Albert; Powell, David Arthur; Lew, Adrian

    2012-03-01

    In this study a number of experiments were performed by taking high-speed footage of the firing spherical steel bullets at different speeds into Perma-Gel, a new synthetic thermoplastic material touted to exhibit similar properties to ordnance ballistic gelatin. We found that the gel undergoes very large and recoverable elastic deformations, which could strongly affect the dynamics of the temporary cavity formed behind the projectile. As with ordnance ballistic gelatin, the diameter of the temporary cavity can be many times the diameter of the projectile, in contrast with that of the permanent cavity which is several times smaller.We also observed that the closure of the cavity chokes the air inside, which could affect its dynamics in noticeable ways. Finally, one of the experiments suggest that the precise model of material failure may not be important to determine the dynamics of the temporary cavity.

  8. Ballistic Missile Defense. Past and Future

    Science.gov (United States)

    2010-04-01

    and deployed. These are the two big questions of the anti-ballistic missile ( ABM ) debate. It must be emphasized that the...is the extreme polarization of the opposing positions that have been taken. Consider this statement: “The whole ABM question touched off so intense...earlier that same year by the Washington Post and ABC News11 reported that 80 percent of the American population was in favor of building a missile

  9. Attacking the Theater Mobile Ballistic Missile Threat

    Science.gov (United States)

    1993-06-01

    and Record, �Theater Ballistic Missile Defense and US Contingency Operations,� 13. 43Greg Myre, Associated Press, �De Klerk Reveals South African...possession). ____. Briefing, subject: �WarBreaker.� 17 December 1992. Myre, Greg. Associated Press. �De Klerk Reveals South African Nuclear...April�3 May 1992, 1,44. Ordway, Frederick I. III and Ronald C. Wakeford. International Missile and Spacecraft Guide. New York: McGraw

  10. New investigations on shock-wave synthesized high-pressure phases in the system Si-Al-O-N

    Science.gov (United States)

    Schlothauer, T.; Greif, A.; Keller, K.; Schwarz, M. R.; Kroke, E.; Heide, G.

    2012-12-01

    The shock-wave synthesis of nanostructured high-pressure phases at a gram-scale permits the analysis of spinel type nitrides with different chemical composition using methods not suitable for microgram amounts of material. Methods with a significant mass loss through the analytical process like TG-MS or FT-IR or bulk methods at the g-scale like 29Si-MAS-NMR or neutron diffraction were used. The synthesis of pure high-pressure modifications (gamma-phases) of different SiAlON-compounds using amorphous H-bearing precursors at pressures of 30-40 GPa is a necessary prerequisite for precise determinations of crystal chemical features. Etching with HF is a well-known method to purify the high-pressure nitrides (Sekine 2002). The etched parts were analyzed by neutron diffraction, TG-MS, and carrier gas hot extraction (CGHE). Volatile elements like H2 and Cl2, as well as non-stoichiometric oxygen and nitrogen, and NOx, H2O are enriched in the disordered rims. This degassing process ends at temperatures of approximately 600°C, while the spinel structure remains well preserved up to 1300°C. Under these conditions the gamma-phases stay unchanged under air, argon and vacuum. Furthermore chlorine, an important impurity of the H-bearing precursors neither influences the synthesized products nor the synthesis process itself. IR-spectroscopy of gamma-Si3(O,N)4 shows that peak shifts of octahedral lattice vibrations (≈ 680 cm-1) and both tetrahedral vibrations (ny3 and ny4) (Jeanloz 1980, Preudhomme & Tarte 1971) to higher frequencies with decreasing oxygen content occur. This effect is also visible in samples contaminated with impurities of low pressure modifications. The more complex structure of gamma-SiAlON and the simultaneously exchange of the cation- and the anion-positions prevents the appearance of this important feature. Yet to be synthesized pure gamma-SiAlON using similar H-bearing precursors is necessary to resolve its structure. Sekine, T., H. He, T. Kobayashi, K

  11. Thermo-Electron Ballistic Coolers or Heaters

    Science.gov (United States)

    Choi, Sang H.

    2003-01-01

    Electronic heat-transfer devices of a proposed type would exploit some of the quantum-wire-like, pseudo-superconducting properties of single-wall carbon nanotubes or, optionally, room-temperature-superconducting polymers (RTSPs). The devices are denoted thermo-electron ballistic (TEB) coolers or heaters because one of the properties that they exploit is the totally or nearly ballistic (dissipation or scattering free) transport of electrons. This property is observed in RTSPs and carbon nanotubes that are free of material and geometric defects, except under conditions in which oscillatory electron motions become coupled with vibrations of the nanotubes. Another relevant property is the high number density of electrons passing through carbon nanotubes -- sufficient to sustain electron current densities as large as 100 MA/square cm. The combination of ballistic motion and large current density should make it possible for TEB devices to operate at low applied potentials while pumping heat at rates several orders of magnitude greater than those of thermoelectric devices. It may also enable them to operate with efficiency close to the Carnot limit. In addition, the proposed TEB devices are expected to operate over a wider temperature range

  12. Targeting Low-Energy Ballistic Lunar Transfers

    Science.gov (United States)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  13. EMS wave logger data processing

    NARCIS (Netherlands)

    Verhagen, H.J.

    2013-01-01

    Waves can be measured in several ways. One way of measuring waves is by measuring the wave pressure at a certain depth using a pressure sensor and calculate the wave information from the pressure record. The EMS wave logger uses a Honeywell MLH 050 PGP 06A pressure sensor. The information is stored

  14. Injuries of the head from backface deformation of ballistic protective helmets under ballistic impact.

    Science.gov (United States)

    Rafaels, Karin A; Cutcliffe, Hattie C; Salzar, Robert S; Davis, Martin; Boggess, Brian; Bush, Bryan; Harris, Robert; Rountree, Mark Steve; Sanderson, Ellory; Campman, Steven; Koch, Spencer; Dale Bass, Cameron R

    2015-01-01

    Modern ballistic helmets defeat penetrating bullets by energy transfer from the projectile to the helmet, producing helmet deformation. This deformation may cause severe injuries without completely perforating the helmet, termed "behind armor blunt trauma" (BABT). As helmets become lighter, the likelihood of larger helmet backface deformation under ballistic impact increases. To characterize the potential for BABT, seven postmortem human head/neck specimens wearing a ballistic protective helmet were exposed to nonperforating impact, using a 9 mm, full metal jacket, 124 grain bullet with velocities of 400-460 m/s. An increasing trend of injury severity was observed, ranging from simple linear fractures to combinations of linear and depressed fractures. Overall, the ability to identify skull fractures resulting from BABT can be used in forensic investigations. Our results demonstrate a high risk of skull fracture due to BABT and necessitate the prevention of BABT as a design factor in future generations of protective gear.

  15. Transition edge sensors with few-mode ballistic thermal isolation

    Science.gov (United States)

    Osman, D.; Withington, S.; Goldie, D. J.; Glowacka, D. M.

    2014-08-01

    We have fabricated Transition Edge Sensors (TESs) whose thermal characteristics are completely characterised by few-mode ballistic phonon exchange with the heat bath. These TESs have exceptionally small amorphous SiNx support legs: 0.2 μm thick, 0.7-1.0 μm wide, and 1.0 to 4.0 μm long. We show, using classical elastic wave theory, that it is only necessary to know the geometry and bulk elastic constants of the material to calculate the thermal conductance and fluctuation noise. Our devices operate in the few-mode regime, between 5 and 7 modes per leg, and have noise equivalent powers (NEPs) of 1.2 aW Hz-1/2. The NEP is dominated by the thermal fluctuation noise in the legs, which itself is dominated by phonon shot-noise. Thus, TESs have been demonstrated whose thermal characteristics are fully accounted for by an elastic noise-wave model. Our current devices, and second-generation devices based on patterned phononic filters, can be used to produce optically compact, mechanically robust, highly sensitive TES imaging arrays, circumventing many of the problems inherent in conventional long-legged designs.

  16. Childhood Obesity Associates Haemodynamic and Vascular Changes That Result in Increased Central Aortic Pressure with Augmented Incident and Reflected Wave Components, without Changes in Peripheral Amplification

    Directory of Open Access Journals (Sweden)

    Juan M. Castro

    2016-01-01

    Full Text Available The aims were to determine if childhood obesity is associated with increased central aortic blood pressure (BP and to characterize haemodynamic and vascular changes associated with BP changes in obese children and adolescents by means of analyzing changes in cardiac output (stroke volume, SV, arterial stiffness (aortic pulse wave velocity, PWV, peripheral vascular resistances (PVR, and net and relative contributions of reflected waves to the aortic pulse wave amplitude. We included 117 subjects (mean/range age: 10 (5–15 years, 49 females, who were obese (OB or had normal weight (NW. Peripheral and central aortic BP, PWV, and pulse wave-derived parameters (augmentation index, amplitude of forward and backward components were measured with tonometry (SphygmoCor and oscillometry (Mobil-O-Graph. With independence of the presence of dyslipidemia, hypertension, or sedentarism, the aortic systolic and pulse BP were higher in OB than in NW subjects. The increase in central BP could not be explained by the elevation in the relative contribution of reflections to the aortic pressure wave and higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP could be explained by an increase in the amplitude of both incident and reflect wave components associated to augmented SV and/or PWV.

  17. Childhood Obesity Associates Haemodynamic and Vascular Changes That Result in Increased Central Aortic Pressure with Augmented Incident and Reflected Wave Components, without Changes in Peripheral Amplification

    Science.gov (United States)

    Castro, Juan M.; García-Espinosa, Victoria; Curcio, Santiago; Arana, Maite; Chiesa, Pedro; Giachetto, Gustavo; Zócalo, Yanina; Bia, Daniel

    2016-01-01

    The aims were to determine if childhood obesity is associated with increased central aortic blood pressure (BP) and to characterize haemodynamic and vascular changes associated with BP changes in obese children and adolescents by means of analyzing changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR), and net and relative contributions of reflected waves to the aortic pulse wave amplitude. We included 117 subjects (mean/range age: 10 (5–15) years, 49 females), who were obese (OB) or had normal weight (NW). Peripheral and central aortic BP, PWV, and pulse wave-derived parameters (augmentation index, amplitude of forward and backward components) were measured with tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). With independence of the presence of dyslipidemia, hypertension, or sedentarism, the aortic systolic and pulse BP were higher in OB than in NW subjects. The increase in central BP could not be explained by the elevation in the relative contribution of reflections to the aortic pressure wave and higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP could be explained by an increase in the amplitude of both incident and reflect wave components associated to augmented SV and/or PWV. PMID:26881081

  18. Improved theory of generalized meteo-ballistic weighting factor functions and their use

    Directory of Open Access Journals (Sweden)

    Vladimir Cech

    2016-06-01

    Full Text Available It follows from the analysis of artillery fire errors that approximately two-thirds of the inaccuracy of indirect artillery fire is caused by inaccuracies in the determination of the meteo parameters included in fire error budget model. Trajectories calculated under non-standard conditions are considered to be perturbed. The tools utilized for the analysis of perturbed trajectories are weighting factor functions (WFFs which are a special kind of sensitivity functions. WFFs are used for calculation of meteo ballistic elements µB (ballistic wind wB, density ρB, virtual temperature τB, pressure pB as well. We have found that the existing theory of WFF calculation has several significant shortcomings. The aim of the article is to present a new, improved theory of generalized WFFs that eliminates the deficiencies found. Using this theory will improve methods for designing firing tables, fire control systems algorithms, and meteo message generation algorithms.

  19. The effects of blood pressure lowering on P-wave dispersion in patients with hypertensive crisis in emergency setting.

    Science.gov (United States)

    Aksoy, Sukru; Gurkan, Ufuk; Oz, Dilaver; Dayi, Sennur Unal; Demirci, Deniz; Eksik, Abdurrahman; Sayar, Nurten; Agirbasli, Mehmet

    2010-01-01

    Hypertensive emergency refers to a severe hypertension (HT) that is associated with new or progressive end-organ damage. In these clinical situations, blood pressure (BP) should be reduced immediately to prevent or minimize organ dysfunction. The present study evaluated the diagnostic value of two electrocardiographic indices in detecting patients, who are at risk for paroxysmal atrial fibrillation (PAF), in the setting hypertensive crisis. The study population consisted of 30 consecutive patients aged ≥40 years, who were admitted to the emergency room with hypertensive crisis. Electrocardiographic (ECG) recordings of the patients were performed before and after the treatment. The minimum (Pmin) and maximum (Pmax) P wave duration on ECG, and P-wave dispersion (P(d)), which was defined as the difference between Pmin and Pmax, were measured. The mean P(d) was 118.0 ± 32.1 and 94.0 ± 44.3 before and after the treatment, respectively. The decrease observed in the mean P(d) was statistically significant (p = 0.005). The mean Pmax was 214.7 ± 37.1 before the treatment, while it was 194.0 ± 47.3 after the treatment, and the difference was significant (p = 0.021). The mean Pmin was 96.7 ± 26.3 and 100.0 ± 41.0 before and after the treatment, respectively; however, the difference was not significant (p = 0.624). Pmax and P(d) display significant changes with acute treatment of HT. There is a need for larger prospective studies to clearly elucidate the diagnostic value of ECG indices, Pmax and P(d) as indicators of future PAF.

  20. 3D velocity distribution of P- and S-waves in a biotite gneiss, measured in oil as the pressure medium: Comparison with velocity measurements in a multi-anvil pressure apparatus and with texture-based calculated data

    Science.gov (United States)

    Lokajíček, T.; Kern, H.; Svitek, T.; Ivankina, T.

    2014-06-01

    Ultrasonic measurements of the 3D velocity distribution of P- and S-waves were performed on a spherical sample of a biotite gneiss from the Outokumpu scientific drill hole. Measurements were done at room temperature and pressures up to 400 and 70 MPa, respectively, in a pressure vessel with oil as a pressure medium. A modified transducer/sample assembly and the installation of a new mechanical system allowed simultaneous measurements of P- and S-wave velocities in 132 independent directions of the sphere on a net in steps of 15°. Proper signals for P- and S-waves could be recorded by coating the sample surface with a high-viscosity shear wave gel and by temporal point contacting of the transmitter and receiver transducers with the sample surface during the measurements. The 3D seismic measurements revealed a strong foliation-related directional dependence (anisotropy) of P- and S-wave velocities, which is confirmed by measurements in a multi-anvil apparatus on a cube-shaped specimen of the same rock. Both experimental approaches show a marked pressure sensitivity of P- and S-wave velocities and velocity anisotropies. With increasing pressure, P- and S-wave velocities increase non-linearly due to progressive closure of micro-cracks. The reverse is true for velocity anisotropy. 3D velocity calculations based on neutron diffraction measurements of crystallographic preferred orientation (CPO) of major minerals show that the intrinsic bulk anisotropy is basically caused by the CPO of biotite constituting about 23 vol.% of the rock. Including the shape of biotite grains and oriented low-aspect ratio microcracks into the modelling increases bulk anisotropy. An important finding from this study is that the measurements on the sample sphere and on the sample cube displayed distinct differences, particularly in shear wave velocities. It is assumed that the differences are due to the different geometries of the samples and the configuration of the transducer-sample assembly

  1. Status of R&D on mitigating the effects of pressure waves for the Spallation Neutron Source mercury target

    Science.gov (United States)

    Riemer, Bernard W.; Wendel, Mark W.; Felde, David K.; Abdou, Ashraf A.; McClintock, David A.

    2012-12-01

    The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of pressure waves in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity - and hence its neutron intensity performance. The R&D program has moved from verification of the beam-induced damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the pressure waves volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effective during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target's beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-induced changes

  2. A Short-Barrelled 105-mm Howitzer for Interior Ballistic Studies

    Science.gov (United States)

    1983-01-01

    PROGRAM ELEMENT, PROJECT, TASK AREA 4 WORK UNIT NUMBERS US Army Ballistic Research Laboratory ATTN: DRDAR-BLI 1L162618AH80 Aberdeen Proving Ground...P )A b f where Pb = Pressure acting on base of the projectile Pf = Engraving and resistive pressure and A = Cross-sectional area of the bore; w...Army Armament R&D Command ATTN: DRDAR-SCA, L. Stiefel B. Brodman DRDAR-LCB-I, D. Spring DRDAR-LCE, R. Walker DRDAR-LCU-CT E. Barrieres R

  3. Unified Application of Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    Science.gov (United States)

    Erickson, Gary E.

    2010-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack. The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  4. Unified Application Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    Science.gov (United States)

    Erickson, Gary E.

    2008-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack (alpha). The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  5. The effect of spherical hub-nose position on pressure drop in an oscillating water column system for wave energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Taha, Z.; Ahmad, N.; Ghazilla, R.A.R.; Yap, H.J.; Ya, T.Y.T.; Passarella, R.; Hasanuddin, I.; Yunus, M. [Malaya Univ. (Malaysia). Centre for Product Design and Manufacturing; Sugiyono [Malaya Univ., (Malaysia). Centre for Product Design and Manufacturing; Gadjah Mada Univ. (Indonesia). Dept. of Mechanical and Industrial Engineering

    2009-07-01

    The use of renewable energy sources as an alternative to conventional fuels was discussed with particular reference to ocean wave energy and its potential to contribute to the energy requirements of coastal nations. Ocean wave energy has been harnessed and converted into electricity using processes and technologies that are environmentally sound. The oscillating water column (OWC) system is considered to be among the most promising technology for harnessing wave energy. This paper presented the results of a study that investigated the pressure drop in an OWC system and the effect of spherical hub-nose position in an annular duct. Computational fluid dynamics (CFD) analysis was used under steady flow conditions for several hub-nose positions to determine the characteristic of pressure drop. The study showed that the hub-nose position influenced the pressure drop in the OWC system. The highest value of the pressure drop in this study occurred when the hub-nose was at the position of 0.0 m relative to the end of the converging cone. The pressure drop decreased when the hub-nose position moved away from the end of converging cone. The lowest value occurred at the position of -0.5 m. It was concluded that despite the numerically small change in pressure drop, this phenomenon should be considered in the design process of the OWC system because of the operational condition of the system at low-pressure pneumatic power. The pressure drop actually reduces the amount of energy that will be converted by the air turbine. 9 refs., 2 tabs., 6 figs.

  6. The internal ballistics of a high: low pressure gun

    Directory of Open Access Journals (Sweden)

    J. N. Kapur

    1957-04-01

    Full Text Available In the present paper the system of equations for the Non-Isothermal Model for a H/L gun has been developed and from this, the systems of equations for Isothermal and Non-isothermal models for orthodox gun and solid fuel rockets have been deduced. The Non-Isothermal Model for H/L gun has been integrated for a tubular charge. For isothermal model, reduction to an equivalent non-leaking problem has been discussed and the partially non-isothermal model has been integrated for the linear law. After all-burnt modification needed in Corner's energy equation is obtained.

  7. Dependence of P-wave dispersion on mean arterial pressure as an independent hemodynamic variable in school children

    Directory of Open Access Journals (Sweden)

    Elibet Chávez González

    2013-09-01

    Full Text Available Introduction:The relationship between diastolic dysfunction and P-wave dispersion (PWD in the electrocardiogram has been studied for some time. In this regard, echocardiography is emerging as a diagnostic tool to improve risk stratification for mild hypertension.Objective:To determine the dependence of PWD on the electrocardiogram and on echocardiographic variables in a pediatric population.Methods: Five hundred and fifteen children from three elementary schools were studiedfrom a total of 565 children. Those whose parents did not want them to take part in the study, as well as those with known congenital diseases, were excluded. Tests including 12-lead surface ECGs and 4 blood pressure (BP measurements were performed. Maximum and minimum P-values were measured, and the PWD on the electrocardiogram was calculated. Echocardiography for structural measurements and the pulsed Doppler of mitral flow were also performed.Results: A significant correlation in statistical variables was found between PWD and mean BP for pre-hypertensive and hypertensive children, i.e., r= 0.32, p <0.01 and r= 0.33, p <0.01, respectively. There was a significant correlation found between PWD and the left atrial area (r= 0.45 and p <0.01.Conclusions: We highlight the dependency between PWD, the electrocardiogram and  mean  blood pressure. We also draw attention to the dependence of PWD on the left atrial area.  This result provides an explanation for earlier changes in atrial electrophysiological and hemodynamic characteristics in pediatric patients.

  8. The Generation of Gravity-Capillary Solitary Waves by a Pressure Source Moving at a Trans-critical Speed

    CERN Document Server

    Masnadi, Naeem

    2016-01-01

    The unsteady response of a water free surface to a localized pressure source moving at constant speed $U$ in the range $0.95c_\\mathrm{min} \\lesssim U \\leq 1.02 c_\\mathrm{min}$, where $c_\\mathrm{min}$ is the minimum phase speed of linear gravity-capillary waves in deep water, is investigated through experiments and numerical simulations. This unsteady response state, which consists of a V-shaped pattern behind the source and features periodic shedding of pairs of depressions from the tips of the V, was first observed qualitatively by Diorio et al. (Phys. Rev. Let., 103, 214502, 2009) and called state III. In the present investigation, cinematic shadowgraph and refraction-based techniques are utilized to measure the temporal evolution of the free surface deformation pattern downstream of the source as it moves along a towing tank, while numerical simulations using the model equation proposed by Cho et al. (J. Fluid Mech., 672, 288-306, 2011) are used to extend the experimental results over longer times than are...

  9. Development and testing of a flexible ballistic neck protection

    NARCIS (Netherlands)

    Roebroeks, G.H.J.J.; Rensink, P.

    2016-01-01

    Sufficient ballistic protection of the neck area would significantly reduce the vulnerability of an infantry soldier. So far this protection is offered by extensions on the ballistic vest or combat helmet. However, the requirements for head agility and the various body to head positions combined wit

  10. Ballistic performance and microstructure of four armor ceramics

    NARCIS (Netherlands)

    Abadjieva, E.; Carton, E.P.

    2013-01-01

    The ballistic behavior of four different armor ceramic materials with thicknesses varying from 3 mm to 14 mm has been investigated. These are two types of alumina Al2O3 armor grades and two types of SiC armor grades produced by different armor ceramic producers. The ballistic study has been performe

  11. Towards reliable simulations of ballistic impact on concrete structures

    NARCIS (Netherlands)

    Khoe, Y.S.; Tyler Street, M.D.; Maravalalu Suresh,, R.S.; Weerheijm, J.

    2013-01-01

    Protection against weapon effects like ballistic impacts, fragmenting shells and explosions is the core business of the Explosions, Ballistics and Protection department of TNO (The Netherlands). Experimental and numerical research is performed to gain and maintain the knowledge to support the Dutch

  12. Ballistic Characterization of the Scalability of Magnesium Alloy AMX602

    Science.gov (United States)

    2015-07-01

    Magnesium Alloy AMX602 by Tyrone L Jones Weapons and Materials Research Directorate, ARL Katsuyoshi Kondoh Joining and Welding Research...formed a collaborative partnership with Osaka University Joining and Welding Research Institute (JWRI), Taber Extrusions, Epson Atmix, Pacific Sowa...Powder Metallurgy 4 5. Fabrication Procedure 4 6. Mechanical Property Analysis 5 7. Ballistic Experimental Procedures 6 8. Ballistic Experimental

  13. The reference ballistic imaging database revisited.

    Science.gov (United States)

    De Ceuster, Jan; Dujardin, Sylvain

    2015-03-01

    A reference ballistic image database (RBID) contains images of cartridge cases fired in firearms that are in circulation: a ballistic fingerprint database. The performance of an RBID was investigated a decade ago by De Kinder et al. using IBIS(®) Heritage™ technology. The results of that study were published in this journal, issue 214. Since then, technologies have evolved quite significantly and novel apparatus have become available on the market. The current research article investigates the efficiency of another automated ballistic imaging system, Evofinder(®) using the same database as used by De Kinder et al. The results demonstrate a significant increase in correlation efficiency: 38% of all matches were on first position of the Evofinder correlation list in comparison to IBIS(®) Heritage™ where only 19% were on the first position. Average correlation times are comparable to the IBIS(®) Heritage™ system. While Evofinder(®) demonstrates specific improvement for mutually correlating different ammunition brands, ammunition dependence of the markings is still strongly influencing the correlation result because the markings may vary considerably. As a consequence a great deal of potential hits (36%) was still far down in the correlation lists (positions 31 and lower). The large database was used to examine the probability of finding a match as a function of correlation list verification. As an example, the RBID study on Evofinder(®) demonstrates that to find at least 90% of all potential matches, at least 43% of the items in the database need to be compared on screen and this for breech face markings and firing pin impression separately. These results, although a clear improvement to the original RBID study, indicate that the implementation of such a database should still not be considered nowadays.

  14. Method of optical self-mixing for pulse wave transit time in comparison with other methods and correlation with blood pressure

    Science.gov (United States)

    Meigas, Kalju; Lass, Jaanus; Kattai, Rain; Karai, Deniss; Kaik, Juri

    2004-07-01

    This paper is a part of research to develop convenient method for continuous monitoring of arterial blood pressure by non-invasive and non-oscillometric way. A simple optical method, using self-mixing in a diode laser, is used for detection of skin surface vibrations near the artery. These vibrations, which can reveal the pulsate propagation of blood pressure waves along the vasculature, are used for pulse wave registration. The registration of the Pulse Wave Transit Time (PWTT) is based on computing the time delay in different regions of the human body using an ECG as a reference signal. In this study, the comparison of method of optical self-mixing with other methods as photoplethysmographic (PPG) and bioimpedance (BI) for PWTT is done. Also correlation of PWTT, obtained with different methods, with arterial blood pressure is calculated. In our study, we used a group of volunteers (34 persons) who made the bicycle exercise test. The test consisted of cycling sessions of increasing workloads during which the HR changed from 60 to 180 beats per minute. In addition, a blood pressure (NIBP) was registered with standard sphygmomanometer once per minute during the test and all NIBP measurement values were synchronized to other signals to find exact time moments where the systolic blood pressure was detected (Korotkoff sounds starting point). Computer later interpolated the blood pressure signal in order to get individual value for every heart cycle. The other signals were measured continuously during all tests. At the end of every session, a recovery period was included until person's NIBP and heart rate (HR) normalized. As a result of our study it turned out that time intervals that were calculated from plethysmographic (PPG) waveforms were in the best correlation with systolic blood pressure. The diastolic pressure does not correlate with any of the parameters representing PWTT. The pulse wave signals measured by laser and piezoelectric transducer are very similar

  15. Going ballistic: Graphene hot electron transistors

    Science.gov (United States)

    Vaziri, S.; Smith, A. D.; Östling, M.; Lupina, G.; Dabrowski, J.; Lippert, G.; Mehr, W.; Driussi, F.; Venica, S.; Di Lecce, V.; Gnudi, A.; König, M.; Ruhl, G.; Belete, M.; Lemme, M. C.

    2015-12-01

    This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance.

  16. More Inaccurate Specifications of Ballistic Coefficients

    Science.gov (United States)

    2012-01-02

    The rifles used in the study were all Remington 700s with factory barrels. The 223 Remington , 308 Winchester, and 30-06 were all ADLs with...Berger 62 grain flat base varmint bullet. This bullet demonstrates excellent accuracy (0.5 MOA) in the Remington 700 test rifle out to 300 yards and...factor. The earlier paper (Courtney and Courtney 2009) reported a BC of 0.308 +/- 0.010 for the 125 grain Nosler Ballistic Tip from the Remington

  17. Dynamic conductance of a ballistic quantum wire

    Energy Technology Data Exchange (ETDEWEB)

    Quan Jun [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Tian Ying [Center of Liberal Education, Zhanjiang Normal University, Zhanjiang 524048 (China); Zhang, Jun, E-mail: ntu_submit@yahoo.c [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Shenzhen Institute of Advanced Integration Technology, Shenzhen 518055 (China); Shao Lexi [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China)

    2011-04-01

    Within the framework of exact linear response theory, we derive a general formula, with which the dynamic conductance of mesoscopic system can be determined in the absence of Coulomb interaction. In addition, we present a solution to the problem of current partition in the system. These allow the derivation of dynamic conductance in time-dependent case. As a natural consequence, the current (charge) conservation and gauge invariance conditions are fulfilled. To give an example, we discuss the dynamic conductance of a ballistic quantum wire, and the effect of contacts on the conductance is also discussed.

  18. Feasibility of ballistic strengthening exercises in neurologic rehabilitation.

    Science.gov (United States)

    Williams, Gavin; Clark, Ross A; Hansson, Jessica; Paterson, Kade

    2014-09-01

    Conventional methods for strength training in neurologic rehabilitation are not task specific for walking. Ballistic strength training was developed to improve the functional transfer of strength training; however, no research has investigated this in neurologic populations. The aim of this pilot study was to evaluate the feasibility of applying ballistic principles to conventional leg strengthening exercises in individuals with mobility limitations as a result of neurologic injuries. Eleven individuals with neurologic injuries completed seated and reclined leg press using conventional and ballistic techniques. A 2 × 2 repeated-measures analysis of variance was used to compare power measures (peak movement height and peak velocity) between exercises and conditions. Peak jump velocity and peak jump height were greater when using the ballistic jump technique rather than the conventional concentric technique (P exercises, the incorporation of ballistic principles was associated with increased peak height and peak velocities.

  19. Impacts of Deflection Nose on Ballistic Trajectory Control Law

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2014-01-01

    Full Text Available The deflection of projectile nose is aimed at changing the motion of the projectile in flight with the theory of motion control and changing the exterior ballistics so as to change its range and increase its accuracy. The law of external ballistics with the deflectable nose is considered as the basis of the design of a flight control system and an important part in the process of projectile development. Based on the existing rigid external ballistic model, this paper establishes an external ballistic calculation model for deflectable nose projectile and further establishes the solving programs accordingly. Different angle of attack, velocity, coefficients of lift, resistance, and moment under the deflection can be obtained in this paper based on the previous experiments and emulation researches. In the end, the author pointed out the laws on the impaction of external ballistic trajectory by the deflection of nose of the missile.

  20. Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. Part 1: Pressure distribution. Part 2: Wall shear stress. Part 3: Simplified formulas for the prediction of surface pressures and skin friction

    Science.gov (United States)

    Adamson, T. C., Jr.; Liou, M. S.; Messiter, A. F.

    1980-01-01

    An asymptotic description is derived for the interaction between a shock wave and a turbulent boundary layer in transonic flow, for a particular limiting case. The dimensionless difference between the external flow velocity and critical sound speed is taken to be much smaller than one, but large in comparison with the dimensionless friction velocity. The basic results are derived for a flat plate, and corrections for longitudinal wall curvature and for flow in a circular pipe are also shown. Solutions are given for the wall pressure distribution and the shape of the shock wave. Solutions for the wall shear stress are obtained, and a criterion for incipient separation is derived. Simplified solutions for both the wall pressure and skin friction distributions in the interaction region are given. These results are presented in a form suitable for use in computer programs.

  1. Short report of an unusual ballistic trauma

    Science.gov (United States)

    Inchingolo, Francesco; Tatullo, Marco; Marrelli, Massimo; Inchingolo, Alessio D.; Pinto, Giorgia; Inchingolo, Angelo M.; Dipalma, Gianna

    2011-01-01

    INTRODUCTION Portable firearms have a relevant medico-legal interest, being a major cause of injury. Bullet entry wounds generally have a particular appearance, including contusion, skin introflection, and simple or excoriated ecchymosis. The skin wound is typically a hole with frayed margins, whose diameter is smaller than that of the bullet. PRESENTATION OF CASE We report the case of a 19-year-old man with ballistic trauma. Examination of the patient's lesions indicated that the bullet had entered from the left mandibular parasymphysis, creating a small hole without the typical bullet wipe and blackening. Subsequently, the bullet seemed to have fractured the left chin region immediately below the lower alveolar process, and it finally stopped in the submandibular area in the suprahyoid region of the neck. DISCUSSION This case is peculiar because the distinctive features of a firearm injury were absent; the lack of bleeding and edema made the case difficult to interpret without additional diagnostic investigations. CONCLUSION Ballistic trauma can manifest in different ways; therefore, internal trauma should be suspected even in the absence of clear external signs. This case report shows how an unusual bullet entry hole can mask quite serious injuries. PMID:22096751

  2. The Dynamic Behaviour of Ballistic Gelatin

    Science.gov (United States)

    Shepherd, C. J.; Appleby-Thomas, G. J.; Hazell, P. J.; Allsop, D. F.

    2009-12-01

    In order to characterise the effect of projectiles it is necessary to understand the mechanism of both penetration and resultant wounding in biological systems. Porcine gelatin is commonly used as a tissue simulant in ballistic tests because it elastically deforms in a similar manner to muscular tissue. Bullet impacts typically occur in the 350-850 m/s range; thus knowledge of the high strain-rate dynamic properties of both the projectile and target materials are desirable to simulate wounds. Unlike projectile materials, relatively little data exists on the dynamic response of flesh simulants. The Hugoniot for a 20 wt.% porcine gelatin, which exhibits a ballistic response similar to that of human tissues at room temperature, was determined using the plate-impact technique at impact velocities of 75-860 m/s. This resulted in impact stresses around three times higher than investigated elsewhere. In US-uP space the Hugoniot had the form US = 1.57+1.77 uP, while in P-uP space it was essentially hydrodynamic. In both cases this was in good agreement with the limited available data from the literature.

  3. Advanced geometries for ballistic neutron guides

    Science.gov (United States)

    Schanzer, Christian; Böni, Peter; Filges, Uwe; Hils, Thomas

    2004-08-01

    Sophisticated neutron guide systems take advantage of supermirrors being used to increase the neutron flux. However, the finite reflectivity of supermirrors becomes a major loss mechanism when many reflections occur, e.g. in long neutron guides and for long wavelengths. In order to reduce the number of reflections, ballistic neutron guides have been proposed. Usually linear tapered sections are used to enlarge the cross-section and finally, focus the beam to the sample. The disadvantages of linear tapering are (i) an inhomogeneous phase space at the sample position and (ii) a decreasing flux with increasing distance from the exit of the guide. We investigate the properties of parabolic and elliptic tapering for ballistic neutron guides, using the Monte Carlo program McStas with a new guide component dedicated for such geometries. We show that the maximum flux can indeed be shifted away from the exit of the guide. In addition we explore the possibilities of parabolic and elliptic geometries to create point like sources for dedicated experimental demands.

  4. Advanced geometries for ballistic neutron guides

    Energy Technology Data Exchange (ETDEWEB)

    Schanzer, Christian E-mail: christian.schanzer@frm2.tum.de; Boeni, Peter; Filges, Uwe; Hils, Thomas

    2004-08-21

    Sophisticated neutron guide systems take advantage of supermirrors being used to increase the neutron flux. However, the finite reflectivity of supermirrors becomes a major loss mechanism when many reflections occur, e.g. in long neutron guides and for long wavelengths. In order to reduce the number of reflections, ballistic neutron guides have been proposed. Usually linear tapered sections are used to enlarge the cross-section and finally, focus the beam to the sample. The disadvantages of linear tapering are (i) an inhomogeneous phase space at the sample position and (ii) a decreasing flux with increasing distance from the exit of the guide. We investigate the properties of parabolic and elliptic tapering for ballistic neutron guides, using the Monte Carlo program McStas with a new guide component dedicated for such geometries. We show that the maximum flux can indeed be shifted away from the exit of the guide. In addition we explore the possibilities of parabolic and elliptic geometries to create point like sources for dedicated experimental demands.

  5. The generation of gravity-capillary solitary waves by a pressure source moving at a trans-critical speed

    Science.gov (United States)

    Masnadi, Naeem; Duncan, James H.

    2017-01-01

    The unsteady response of a water free surface to a localized pressure source moving at constant speed $U$ in the range $0.95c_\\mathrm{min} \\lesssim U \\leq 1.02 c_\\mathrm{min}$, where $c_\\mathrm{min}$ is the minimum phase speed of linear gravity-capillary waves in deep water, is investigated through experiments and numerical simulations. This unsteady response state, which consists of a V-shaped pattern behind the source and features periodic shedding of pairs of depressions from the tips of the V, was first observed qualitatively by Diorio et al. (Phys. Rev. Let., 103, 214502, 2009) and called state III. In the present investigation, cinematic shadowgraph and refraction-based techniques are utilized to measure the temporal evolution of the free surface deformation pattern downstream of the source as it moves along a towing tank, while numerical simulations of the model equation described by Cho et al. (J. Fluid Mech., 672, 288-306, 2011) are used to extend the experimental results over longer times than are possible in the experiments. From the experiments, it is found that the speed-amplitude characteristics and the shape of the depressions are nearly the same as those of the freely propagating gravity-capillary lumps of inviscid potential theory. The decay rate of the depressions is measured from their height-time characteristics, which are well fitted by an exponential decay law with an order 1 decay constant. It is found that the shedding period of the depression pairs decreases with increasing source strength and speed. As the source speed approaches $c_\\mathrm{min}$, this period tends to about 1~s for all source magnitudes. At the low-speed boundary of state III, a new response with unsteady asymmetric shedding of depressions is found. This response is also predicted by the model equation.

  6. Field-induced charge-density-wave transitions in the organic metal α-(BEDT-TTF)2KHg(SCN)4 under pressure

    Science.gov (United States)

    Andres, D.; Kartsovnik, M. V.; Biberacher, W.; Neumaier, K.; Sheikin, I.; Müller, H.; Kushch, N. D.

    2011-10-01

    Successive magnetic-field-induced charge-density-wave transitions in the layered molecular conductor α-(BEDT-TTF)2KHg(SCN)4 are studied in a hydrostatic pressure regime in which the zero field charge-density- wave (CDW) state is completely suppressed. It is shown that the orbital effect of the magnetic field restores the density wave, while orbital quantization induces transitions between different CDW states as the field strength is varied. The latter show up as distinct anomalies in the magnetoresistance as a function of field. The interplay between the orbital and Pauli paramagnetic effects, which act, respectively, to enhance and to suppress the CDW instability, is particularly manifest in the angular dependence of the field-induced anomalies.

  7. Effects of Acupuncture Stimulation on the Radial artery’s Pressure Pulse Wave in Healthy Young Participants: Protocol for a prospective, single-Arm, Exploratory, Clinical Study

    OpenAIRE

    Jae-Young Shin; Boncho Ku; Tae-Hun Kim; Jang Han Bae; Min-Ho Jun; Jun-Hwan Lee; Kim, Jaeuk U.

    2016-01-01

    Introduction: This study aims to investigate the effects of acupuncture stimulation on the radial artery’s pressure pulse wave, along with various hemodynamic parameters, and to explore the possible underlying mechanism of pulse diagnosis in healthy participants in their twenties. Methods and analysis: This study is a prospective, single-arm, exploratory clinical study. A total of 25 healthy participants, without regard to gender, in their twenties will be recruited by physicians. Written inf...

  8. On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2015-01-01

    Full Text Available At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements.

  9. Comparison of EMS ultrasonic pressure ballistic lithotripsy and holmium laser lithotripsy in ther-apy of complex renal calculi%EMS 超声-气压弹道碎石与微通道钬激光碎石治疗复杂性肾结石对比研究

    Institute of Scientific and Technical Information of China (English)

    安家利

    2016-01-01

    目的:比较 EMS 超声-气压弹道碎石与微通道钬激光碎石治疗复杂性肾结石的临床疗效。方法选择2012年1月至2015年1月收治的400例复杂性肾结石患者作为研究对象,根据其治疗方式分为两组,每组200例,观察组给予 EMS 超声-气压弹道碎石术治疗,对照组给予微通道钬激光碎石术治疗,比较两组患者临床疗效、围术期情况及并发症发生率。结果观察组碎石时间、造瘘管留置时间、住院时间均低于对照组(P ﹤0.05);观察组鹿角形结石患者术后5 d、1个月清除率分别高于对照组(P ﹤0.05);两组患者术后并发症发生率比较差异均未见统计学意义(P ﹥0.05)。结论 EMS 超声-气压弹道碎石术治疗复杂性肾结石效果显著,能促进患者早期康复,值得临床重视。%Objective To compare the clinical curative effect of EMS ultrasonic pressure ballistic lithotripsy and holmium laser lithotripsy in therapy of complex renal calculi. Methods From January 2012 to January 2015,400 patients with complex renal calculi were selected as the research objects,and were divided into two groups according to different treatment methods with 200 cases in each group. The observation group were treated by the EMS ultrasonic and pneumatic lithotripsy,control group were trea-ted by micro channel holmium laser lithotripsy. The clinical curative effect,confining operation period and the incidence of complications were compared between the two groups. Results The lithotripsy time,making the fistula indwelling time and hospitalization time in observation group were lower than those in the control group(P ﹤ 0. 05);the clearance rates of patients with staghorn calculi in observation group 5 d,one month after operation were higher than those in control group(P ﹤ 0. 05);the postopera-tive complication rate after operation had no significant difference between the two groups(P ﹥ 0. 05). Conclusions EMS

  10. Effect of Clamping Rigidity of the Armour on Ballistic Performance

    Directory of Open Access Journals (Sweden)

    S. N. Dikshit

    1992-04-01

    Full Text Available Influence of the manner in which the armour plates are held during their ballistic testing on the armour performance, has been evaluated. One armour plate was clamped rigidly to the test stand while a second plate of identical composition, hardness, and dimensions was hung loosely from the target holder. Both these plates were impacted with the same type of projectiles and over the same impact velocity range. The nature of ballistic damage evaluated indicates that the manner in which the armour is held during ballistic testing has a negligible influence on its performance at least when the mass of the plate is substantially higher than that of the projectile.

  11. Study on Titanium Alloy TC4 Ballistic Penetration Resistance Part Ⅰ: Ballistic Impact Tests

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tao; CHEN Wei; GUAN Yupu; GAO Deping

    2012-01-01

    Ballistic impact test of different-scale casings is an efficient way to demonstrate the casing containment capability at the preliminary design stage of the engine.For the sake of studying the titanium alloy TC4 casing performance,the ballistic tests of flat and curved simulation casing are implemented by using two flat blades of different sizes as the projectile.The impact mechanism and failure of the target are discussed.Impact of the projectile is a highly nonlinear transient process with the large deformation of the target.On the impact,failures of the flat casing and the subscale casing are similar,concluding two parts,the global dishing and localized ductile tearing.The main localized failure mode combines plugging (shear) and petaling (shear) if the projectile perforates or penetrates,while crater (shear) if the projectile rebounds.The ballistic limit equation is verified by the test data and the results show that this empirical equation could be a practical way to estimate the critical velocity.

  12. Ballistics of space launch by a rail gun

    Science.gov (United States)

    Panin, Alexander

    2010-10-01

    The idea of using a big gun to launch objects to space has been around for years -- even Isaac Newton considered the concept. However the technology of accelerating a payload with a gun only recently began approaching orbital velocity (8 km/sec). NASA is currently experimenting with a rail gun which utilizes a magnetic field powered by electricity to accelerate a projectile along a set of rails, similar to train rails. Velocities up to 3 km/sec have been reported for small projectiles, and it seems that orbital velocities can soon become a reality too. We model a launch of various projectiles from Earth surface into the elevation corresponding to the low Earth orbit (about 200-250 km above Earth's surface). The goal of this modeling is to study feasibility of such launch (and accelerations induced), and the ballistics of the flight via Earth's atmosphere (the trajectory, air drag induced, pressure and temperature generated by air drag, etc) and thus the requirements for a mass, size, strength, heat shield, and general design of a payload capsule.

  13. Ballistic reentry vehicles dispersion due to precession stoppage

    Science.gov (United States)

    Lin, T. C.; Grabowsky, W. R.; Yelmgren, K. E.; Landa, M.

    1982-08-01

    Ballistic reentry vehicle (RV) precession stoppage phenomena are investigated analytically and several postulated reasons for its occurrence are discussed. Both analytical solutions and six-degree-of-freedom (6DOF) simulations are presented. In addition to the familiar phenomena of roll through zero (RTZ), roll near zero (RNZ) and angle-of-attack divergence, there are four additional aerodynamic forcing functions that are found to be particularly interesting and significant since they can induce the so-called 'space-fixed-trim' phenomena, i.e., the lift-vector becomes momentarily stationary in space. These four forcing functions are: (1) a shift from body-fixed to wind-fixed trim moment in high freestream dynamic pressure environments; (2) RV with transient unstable aerodynamic stability derivative; (3) trim plane migrations induced by a series of asymmetric nose spallations, and (4) a Magnus-type out-of-plane moment in conjunction with the wind-fixed moment induced by ablation lag phenomena. When this occurs, the trajectory deflection becomes prohibitively large. According to the present analytical/numerical results, the initial spin rate can be crucial for the magnitude as well as the direction of the RV dispersion. Finally, some possible physical mechanisms which would cause RV precession stoppage are suggested.

  14. Incident shock wave attenuation in oscillatory tube and influence on performance of pressure wave refrigerator%振荡管内入射激波衰减及其对冷效应的影响

    Institute of Scientific and Technical Information of China (English)

    郑闽锋; 刘曦; 黄成; 林跃东; 雷晓健; 李学来

    2014-01-01

    The pressure wave refrigerator represents a simple arrangement for gas cooling by its decompression and has many applications in chemical processes and energy transformation. The mechanism of the cooling effect of oscillatory tube is the conversion of the pressure energy of gas to heat through the movement of pressure waves, which are moving shock wave and unsteady expansion wave. In the present paper, the regular pattern of incident shock wave attenuation and its influence on the performance of pressure wave refrigerator are investigated by means of a single-tube set up. In the experiments, the expansion ratio is from 2.0 to 6.0, the relative length of the oscillatory tube L/d is from 87 to 737, and the exciting frequency is from 10 Hz to 240 Hz. The experimental results show that the relative strength of incident shock wave is reduced with the increase of relative position in length x/L because the energy of the reflected shock wave is exhausted by the viscosity and friction of the gas inside the tube. The other reason is the result of the gas in the tube pressurized and heated by the shock wave. The shock wave strength is also influenced by transmission and reflection effects resulted from the reflected shock wave. When the tube is relatively short, the relative strength of incident shock wave is less reduced as the tube length decreases, while the strength of the reflected shock wave at the closed end of the tube increases. The maximum refrigeration efficiencyηmax of the refrigerator increases with the tube length, but the value ofηmax is not affected obviously when the tube length increases to some value. The recommended optimal tube length L/d is 300-435 for the tube in this experiment. It helps to improve the performance of the pressure wave refrigerator under variable work condition when the amplitude of the refrigeration efficiency fluctuation is reduced as the length increases. The relative strength of the incident shock wave attenuation is concerned

  15. Broadband hydroseismograms observed by closed borehole wells in the Kamioka mine, central Japan: Response of pore pressure to seismic waves from 0.05 to 2 Hz

    Science.gov (United States)

    Kano, Yasuyuki; Yanagidani, Takashi

    2006-03-01

    We obtained broadband hydroseismograms by monitoring the pore pressure changes of a rock mass in the Kamioka mine, using borehole wells. The wellhead was sealed to maintain an undrained condition, under which there is no flow of water through the interface between the well and the rock mass. This reduces the wellbore storage effect, which can cause a high-frequency cutoff response for systems of conventional open wells and rock mass. Using these closed borehole wells, 16 hydroseismograms were recorded for earthquakes in a range of magnitudes of 4.5-7.9 and epicentral distances of 1.0°-71.6°. Direct P waves, SV waves converted to P, and Rayleigh phases are clearly observed on the hydroseismograms. The similarity between hydroseismograms and seismograms reveals a clear relationship between radial ground velocity and pore pressure. The relationship is expressed as a zero-order system, which is characterized by no distortion or time lag between the input and output, and the pore pressure has no coupling with shear deformation. These results are consistent with an undrained constitutive relation of linear poroelastic theory and confirm that the relation is valid for the seismic frequency range. We determined in situ values of pore pressure sensitivity to volumetric change of the rock mass, which were then used to estimate in situ Skempton coefficients with values of 0.70-0.85.

  16. Relationship between pressure wave amplitude and esophageal bolus clearance assessed by combined manometry and multichannel intraluminal impedance measurement

    NARCIS (Netherlands)

    Nguyen, Nam Q.; Tippett, Marcus; Smout, Andre J. P. M.; Holloway, Richard H.

    2006-01-01

    OBJECTIVES: Esophageal wave amplitude is an important determinant of esophageal clearance. A threshold of 30 mmHg is widely accepted as the threshold for effective clearance in the distal esophagus. However, the precise relationship between wave amplitude and clearance has received relatively little

  17. Wave Pressures and Loads on a Small Scale Model of the Svåheia SSG Pilot Project

    DEFF Research Database (Denmark)

    Buccino, Mariano; Vicinanza, Diego; Ciardulli, Francesco;

    2011-01-01

    The paper reports on 2D small scale experiments conducted to investigate wave loadings acting on a pilot project of device for the conversion of wave energy into electricity. The conversion concept is based on the overtopping principle and the structure is worldwide known with the acronym SSG. Th...

  18. Ballistic energy transport in PEG oligomers

    Directory of Open Access Journals (Sweden)

    Kireev Victor V.

    2013-03-01

    Full Text Available Energy transport between the terminal groups of the azido-PEG-succinimide ester compounds with a number of repeating PEG units of 0, 4, 8, and 12 was studied using relaxation-assisted two-dimensional infrared spectroscopy. The through-bond energy transport time, evaluated as the waiting time at which the cross peak maximum is reached, Tmax, was found to be linearly dependent on the chain length for chain lengths up to 60 Å suggesting a ballistic energy transport regime. The through-bond energy transport speed is found to be ca. 500 m/s. The cross-peak amplitude at the maximum decays exponentially with the chain length with a characteristic decay distance of 15.7 ± 1 Å. Substantial mode delocalization across the PEG bridge is found, which can support the energy propagation as a wavepacket.

  19. Real-world ballistics: A dropped bucket

    CERN Document Server

    Hogg, David W

    2007-01-01

    I discuss an apparently simple ballistics problem: the time it takes an object to fall a small vertical distance near the surface of the Earth. It turns out to be not so simple; I spend a great deal of time on the quantitative assessment of the assumptions involved, especially with regards to the influence of the air. The point is \\emph{not} to solve the problem; indeed I don't even end up solving the problem exactly. I introduce dimensional analysis to perform all of the calculations approximately. The principal theme of the lecture is that \\emph{real} physics can be very different from ``textbook'' physics, since in the real world you aren't ever told what equations are appropriate, or why.

  20. Gate tuneable beamsplitter in ballistic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Rickhaus, Peter; Makk, Péter, E-mail: Peter.Makk@unibas.ch; Schönenberger, Christian [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Liu, Ming-Hao; Richter, Klaus [Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg (Germany)

    2015-12-21

    We present a beam splitter in a suspended, ballistic, multiterminal, bilayer graphene device. By using local bottomgates, a p-n interface tilted with respect to the current direction can be formed. We show that the p-n interface acts as a semi-transparent mirror in the bipolar regime and that the reflectance and transmittance of the p-n interface can be tuned by the gate voltages. Moreover, by studying the conductance features appearing in magnetic field, we demonstrate that the position of the p-n interface can be moved by 1 μm. The herein presented beamsplitter device can form the basis of electron-optic interferometers in graphene.

  1. Ballistic miniband conduction in a graphene superlattice

    Science.gov (United States)

    Lee, Menyoung; Wallbank, John R.; Gallagher, Patrick; Watanabe, Kenji; Taniguchi, Takashi; Fal'ko, Vladimir I.; Goldhaber-Gordon, David

    2016-09-01

    Rational design of long-period artificial lattices yields effects unavailable in simple solids. The moiré pattern in highly aligned graphene/hexagonal boron nitride (h-BN) heterostructures is a lateral superlattice with high electron mobility and an unusual electronic dispersion whose miniband edges and saddle points can be reached by electrostatic gating. We investigated the dynamics of electrons in moiré minibands by measuring ballistic transport between adjacent local contacts in a magnetic field, known as the transverse electron focusing effect. At low temperatures, we observed caustics of skipping orbits extending over hundreds of superlattice periods, reversals of the cyclotron revolution for successive minibands, and breakdown of cyclotron motion near van Hove singularities. At high temperatures, electron-electron collisions suppress focusing. Probing such miniband conduction properties is a necessity for engineering novel transport behaviors in superlattice devices.

  2. Ballistic Missile Defense: New Plans, Old Challenges

    Directory of Open Access Journals (Sweden)

    Elizabeth Zolotukhina

    2010-01-01

    Full Text Available On September 17, 2009—the 70th anniversary of the Soviet invasion of Poland in 1939 that marked the beginning of World War II—the Obama Administration announced its intention to shelve plans for the U.S. Ballistic Missile Defense (BMD that had been developed under former President George W. Bush. Pointing to a new intelligence assessment, President Obama argued that his predecessor's plan to deploy an X-band radar station outside of Prague, Czech Republic, and 10 two-stage interceptor missiles in Poland would not adequately protect America and its European allies from the Iranian threat and reiterated his opposition to utilizing unproven technology in any European BMD architecture.

  3. Ballistics firearm identification by digital holography

    Institute of Scientific and Technical Information of China (English)

    LI Dong-guang

    2009-01-01

    The need for firearm identification systems by police services continues to increase with greater accessibility to weapons in the national and international contexts. The difficulties associated with traditional imaging of ballistics specimens are numerous, and include the smallness of the samples, the nature of the surfaces and shapes for the cartridge cases and projectiles. The digital holography has been introduced to create the 3D image of the fired bullets in order to identify firearms. In digital holography a CCD camera records optically generated holograms which is then reconstructed numerically by a calculation of scalar diffraction in the Fresnel approximation. The digital photography facilitates real time transmission of the message via traditional communication methods. In this paper the principle of digital holography and its application to the 3D image encryption-decryption were reviewed. The experimental results of firearm identification recording using digital holography and their numerical reconstruction were presented.

  4. Ultrasonic P-wave velocity measurements with variable effective pressure at the boundary between slope basin sediments and the accretionary prism: IODP Expedition 315 Site C0001

    Science.gov (United States)

    Hashimoto, Y.; Knuth, M. W.; Tobin, H. J.; 314/315/316 Scientist, I.

    2008-12-01

    IODP Expedition 315 Site C0001 is located on the hanging wall of the midslope megasplay fault in the Nankai subduction zone off Kii peninsula (SW Japan), and penetrated an unconformity between ~200 m thick slope basin sediments and the accretionary prism. While a down-section porosity increase was clearly observed at the boundary from ~50% to ~60%, logging velocity does not appear to decrease at the boundary, which suggests that different diagenetic processes might exist above and below the boundary. In this study, we conducted ultrasonic P-wave velocity measurements with pore pressure control. We also conducted observations of sediment and chemical analysis. We examined the relationships between the acoustic properties, sediment textures, logging data from IODP Expedition 314 Site C0001 and data from shipboard core analysis. The ultrasonic P-wave velocity measurements were conducted under constant pore pressure (500 kPa) and varying confining pressure to control effective pressure. The confining pressure ranges from 550 kPa to a maximum calculated from the density of overlying sediments (lithostatic pressure - hydrostatic pressure). 8 samples were analyzed, located from ~70 m to ~450 m below the sea floor. P-wave velocity ranges from ~1620 m/s to ~1990 m/s under the hydrostatic pressure condition. These velocities are in good agreement with the logging data. Porosity-velocity relationship in the analyzed data also coincide with that observed in the logging data. Samples shallower than ~300 m fall within previously-defined empirical relationships for normal- and high- consolidation. The deeper samples (at ~370 m and ~450 m below sea floor) show much higher velocity than that predicted by the empirical relationship, suggesting that significant cementation is present in those samples. The textural observations of sediments indicate a decrease in pore space with depth. Quartz and feldspar grains are surrounded by clay mineral matrices. Grain size seems to be almost

  5. Continuously Phase-Modulated Standing Surface Acoustic Waves for Separation of Particles and Cells in Microfluidic Channels Containing Multiple Pressure Nodes

    CERN Document Server

    Lee, Junseok; Kang, Byungjun; Lee, Hyungsuk

    2016-01-01

    This paper describes continuously phase-modulated standing surface acoustic waves (CPM-SSAW) and its application for particle separation in multiple pressure nodes. A linear change of phase in CPM-SSAW applies a force to particles whose magnitude depends on their size and contrast factors. During continuous phase modulation, we demonstrate that particles with the target dimension are translated in the direction of moving pressure nodes, whereas smaller particles show oscillatory movements. The rate of phase modulation is optimized for separation of target particles from the relationship between mean particle velocity and period of oscillation. The developed technique is applied to separate particles of the target dimension from the particle mixture. Furthermore, we also demonstrate human keratinocyte cells can be separated in the cell and bead mixture. The separation technique is incorporated with a microfluidic channel spanning multiple pressure nodes, which is advantageous over separation in a single pressu...

  6. Evaluation of the Colin STBP-680 at rest and during exercise: an automated blood pressure monitor using R-wave gating.

    Science.gov (United States)

    Bond, V; Bassett, D R; Howley, E T; Lewis, J; Walker, A J; Swan, P D; Tearney, R J; Adams, R G

    1993-06-01

    The application of automated blood pressure measurement during exercise has been limited by inaccuracies introduced by the effects of accompanying motion and noise. We evaluated a newly developed automated blood pressure monitor for measuring exercise blood pressure (Colin STBP-680; Colin, San Antonio, Texas, USA). The STBP-680 uses acoustic transduction with the assistance of the electrocardiogram R-wave to trigger the sampling period for blood pressure measurement. The automated monitor readings were compared with simultaneous technician mercury sphygmomanometric readings in the same arm. Blood pressure was measured in 18 men at rest and during exercise at 40% VO2 peak, (low intensity), 70% VO2 peak (moderate intensity) and VO2 peak (high intensity) on the cycle ergometer. Mean(s.d.) systolic blood pressure difference between the automated monitor and mercury manometer readings at rest and during exercise at low, moderate and high work intensities were 3(0) mmHg, 3(2) mmHg, 1(1) mmHg, and 0(11) mmHg respectively (analysis of variance; P > 0.05). Resting diastolic blood pressure obtained with the STBP-680 was similar to the mercury manometer readings (78(10) versus 81(7) mmHg (P > 0.05). Exercise diastolic pressure at the low level of work intensity was almost identical between the automated monitor and mercury manometer readings (64(8) versus 65(10) mmHg (not significant)). Diastolic blood pressure readings between the STBP-680 and mercury manometer showed a greater difference at the moderate and high workloads (11 mmHg and 9 mmHg, respectively), but this difference was not significant (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Phase transition and optical properties of CaCl2 under high pressure by ab initio pseudopotential plane-wave calculations

    Science.gov (United States)

    Liu, Y. H.; Ma, Y. M.; He, Z.; Cui, T.; Liu, B. B.; Zou, G. T.

    2007-10-01

    We present a detailed investigation of CaCl2 under high pressure in CaCl2 (Pnnm,Z = 2) and α-PbO2 (Pbcn, Z = 4) phases, respectively. Theoretical calculations are performed by using the ab initio pseudopotential plane-wave method based on the density functional method. We estimate the transition pressure between the two phases by the crossing point of their enthalpies, which are equivalent to the Gibbs free energy at zero temperature, after optimizing the structures under high pressure. Our results show that the transition happens at about 2.9 GPa, which is in agreement with the experimental data. We calculate the structural parameters, charge transfers, bond structures, density of states and optical properties. The calculated results show that there are no charge transfers in CaCl2 structure under high pressure. It is found that the transitions from the Cl 3p to Ca 4s and Cl 3s to Ca 3p orbitals contribute mainly to the dielectric function. The optical properties of CaCl2 (Pnnm, Z = 2) do not vary much under pressure. However, some of the dispersion curves of optical constants in the α-PbO2 (Pbcn, Z = 4) phase are changed significantly under pressure.

  8. Phase transition and optical properties of CaCl{sub 2} under high pressure by ab initio pseudopotential plane-wave calculations

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y H; Ma, Y M; He, Z; Cui, T; Liu, B B; Zou, G T [National Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2007-10-24

    We present a detailed investigation of CaCl{sub 2} under high pressure in CaCl{sub 2} (Pnnm,Z = 2) and {alpha}-PbO{sub 2} (Pbcn, Z = 4) phases, respectively. Theoretical calculations are performed by using the ab initio pseudopotential plane-wave method based on the density functional method. We estimate the transition pressure between the two phases by the crossing point of their enthalpies, which are equivalent to the Gibbs free energy at zero temperature, after optimizing the structures under high pressure. Our results show that the transition happens at about 2.9 GPa, which is in agreement with the experimental data. We calculate the structural parameters, charge transfers, bond structures, density of states and optical properties. The calculated results show that there are no charge transfers in CaCl{sub 2} structure under high pressure. It is found that the transitions from the Cl 3p to Ca 4s and Cl 3s to Ca 3p orbitals contribute mainly to the dielectric function. The optical properties of CaCl{sub 2} (Pnnm, Z = 2) do not vary much under pressure. However, some of the dispersion curves of optical constants in the {alpha}-PbO{sub 2} (Pbcn, Z = 4) phase are changed significantly under pressure.

  9. CTD, current meter, pressure gauge, and wave spectra data from fixed platforms and other platforms from the Coastal Waters of California as part of the Santa Barbara Channel project from 27 April 1983 to 04 January 1985 (NODC Accession 8500177)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD, current meter, pressure gauge, and wave spectra data were collected from fixed platforms and other platforms from the Coastal Waters of California from 27 April...

  10. Underway pressure, temperature, and salinity data from the MOANA WAVE from the Pacific warm pool in support of the Coupled Ocean-Atmosphere Response Experiment (COARE) from 02 February 1993 to 21 February 1993 (NODC Accession 9600090)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pressure, temperature, and salinity data were collected while underway from the MOANA WAVE from the Pacific warm pool. Data were collected in support of the Coupled...

  11. The ballistic Mars hopper: An alternative Mars mobility concept

    OpenAIRE

    1987-01-01

    The ballistic Mars hopper is proposed as an alternative mobility concept for unmanned exploration of the martian surface. In the ballistic Mars hopper concept, oxygen and carbon monoxide produced from the martian atmosphere are used as propellants in a rocket propulsion system for an unmanned vehicle on suborbital trajectories between landing sights separated by distances of up to 1000 km. This mobility concept is seen as uniquely capable of allowing both intensive and extensive exploration o...

  12. An innovative method to measure the peripheral arterial elasticity: spring constant modeling based on the arterial pressure wave with radial vibration.

    Science.gov (United States)

    Wei, Ching-Chuan

    2011-11-01

    In this study, we propose an innovative method for the direct measurement of the peripheral artery elasticity using a spring constant model, based on the arterial pressure wave equation, vibrating in a radial direction. By means of the boundary condition of the pressure wave equation at the maximum peak, we can derive the spring constant used for evaluating peripheral arterial elasticity. The calculated spring constants of six typical subjects show a coincidence with their proper arterial elasticities. Furthermore, the comparison between the spring constant method and pulse wave velocity (PWV) was investigated in 70 subjects (21-64 years, 47 normotensives and 23 hypertensives). The results reveal a significant negative correlation for the spring constant vs. PWV (correlation coefficient = -0.663, p constant method to assess the arterial elasticity is carefully verified, and it is shown to be effective as well as fast. This method should be useful for healthcare, not only in improving clinical diagnosis of arterial stiffness but also in screening subjects for early evidence of cardio-vascular diseases and in monitoring responses to therapy in the future.

  13. Analysis of quantum semiconductor heterostructures by ballistic electron emission spectroscopy

    Science.gov (United States)

    Guthrie, Daniel K.

    1998-09-01

    The microelectronics industry is diligently working to achieve the goal of gigascale integration (GSI) by early in the 21st century. For the past twenty-five years, progress toward this goal has been made by continually scaling down device technology. Unfortunately, this trend cannot continue to the point of producing arbitrarily small device sizes. One possible solution to this problem that is currently under intensive study is the relatively new area of quantum devices. Quantum devices represent a new class of microelectronic devices that operate by utilizing the wave-like nature (reflection, refraction, and confinement) of electrons together with the laws of quantum mechanics to construct useful devices. One difficulty associated with these structures is the absence of measurement techniques that can fully characterize carrier transport in such devices. This thesis addresses this need by focusing on the study of carrier transport in quantum semiconductor heterostructures using a relatively new and versatile measurement technique known as ballistic electron emission spectroscopy (BEES). To achieve this goal, a systematic approach that encompasses a set of progressively more complex structures is utilized. First, the simplest BEES structure possible, the metal/semiconductor interface, is thoroughly investigated in order to provide a foundation for measurements on more the complex structures. By modifying the semiclassical model commonly used to describe the experimental BEES spectrum, a very complete and accurate description of the basic structure has been achieved. Next, a very simple semiconductor heterostructure, a Ga1-xAlxAs single-barrier structure, was measured and analyzed. Low-temperature measurements on this structure were used to investigate the band structure and electron-wave interference effects in the Ga1-xAlxAs single barrier structure. These measurements are extended to a simple quantum device by designing, measuring, and analyzing a set of

  14. A Residual Mass Ballistic Testing Method to Compare Armor Materials or Components (Residual Mass Ballistic Testing Method)

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin Langhorst; Thomas M Lillo; Henry S Chu

    2014-05-01

    A statistics based ballistic test method is presented for use when comparing multiple groups of test articles of unknown relative ballistic perforation resistance. The method is intended to be more efficient than many traditional methods for research and development testing. To establish the validity of the method, it is employed in this study to compare test groups of known relative ballistic performance. Multiple groups of test articles were perforated using consistent projectiles and impact conditions. Test groups were made of rolled homogeneous armor (RHA) plates and differed in thickness. After perforation, each residual projectile was captured behind the target and its mass was measured. The residual masses measured for each test group were analyzed to provide ballistic performance rankings with associated confidence levels. When compared to traditional V50 methods, the residual mass (RM) method was found to require fewer test events and be more tolerant of variations in impact conditions.

  15. The application of a calibrated 3D ballistic trajectory model to ballistic hazard assessments at Upper Te Maari, Tongariro

    Science.gov (United States)

    Fitzgerald, R. H.; Tsunematsu, K.; Kennedy, B. M.; Breard, E. C. P.; Lube, G.; Wilson, T. M.; Jolly, A. D.; Pawson, J.; Rosenberg, M. D.; Cronin, S. J.

    2014-10-01

    On 6 August, 2012, Upper Te Maari Crater, Tongariro volcano, New Zealand, erupted for the first time in over one hundred years. Multiple vents were activated during the hydrothermal eruption, ejecting blocks up to 2.3 km and impacting ~ 2.6 km of the Tongariro Alpine Crossing (TAC) hiking track. Ballistic impact craters were mapped to calibrate a 3D ballistic trajectory model for the eruption. This was further used to inform future ballistic hazard. Orthophoto mapping revealed 3587 impact craters with a mean diameter of 2.4 m. However, field mapping of accessible regions indicated an average of at least four times more observable impact craters and a smaller mean crater diameter of 1.2 m. By combining the orthophoto and ground-truthed impact frequency and size distribution data, we estimate that approximately 13,200 ballistic projectiles were generated during the eruption. The 3D ballistic trajectory model and a series of inverse models were used to constrain the eruption directions, angles and velocities. When combined with eruption observations and geophysical observations, the model indicates that the blocks were ejected in five variously directed eruption pulses, in total lasting 19 s. The model successfully reproduced the mapped impact distribution using a mean initial particle velocity of 200 m/s with an accompanying average gas flow velocity over a 400 m radius of 150 m/s. We apply the calibrated model to assess ballistic hazard from the August eruption along the TAC. By taking the field mapped spatial density of impacts and an assumption that an average ballistic impact will cause serious injury or death (casualty) over an 8 m2 area, we estimate that the probability of casualty ranges from 1% to 16% along the affected track (assuming an eruption during the time of exposure). Future ballistic hazard and probabilities of casualty along the TAC are also assessed through application of the calibrated model. We model a magnitude larger eruption and illustrate

  16. On the response of a water surface to a surface pressure source moving at trans-critical gravity-capillary wave speeds

    Science.gov (United States)

    Masnadi, Naeem; Cho, Yeunwoo; Duncan, James H.; Akylas, Triantaphyllos

    2015-11-01

    The non-linear response of a water free surface to a pressure source moving at speeds near the minimum speed of linear gravity-capillary waves (Cmin ~ 23 cm/s) is investigated with experiments and theory. In the experiments, waves are generated by a vertically oriented air-jet that moves at a constant speed over the water surface in a long tank. The 3-D surface shape behind the air-jet is measured using a cinematic refraction-based technique combined with an LIF technique. At towing speeds just below Cmin, an unsteady pattern is formed where localized depressions periodically appear in pairs and move away from the source along the arms of a downstream V-shaped pattern. This behavior is analogous to the periodic shedding of solitary waves upstream of a source moving at the maximum wave speed in shallow water. The gravity-capillary depressions are rapidly damped by viscosity and their speed-amplitude characteristics closely match those from inviscid calculations of gravity-capillary lumps. The shedding frequency of the lumps in the present experiments increases with both increasing towing speed and air-flow rate. Predictions of this behavior using a model equation that incorporates damping and a quadratic nonlinearity are in good agreement with the experiments. The partial support of the National Science Foundation under grant OCE0751853 is gratefully acknowledged.

  17. Proof of Concept of Crack Localization Using Negative Pressure Waves in Closed Tubes for Later Application in Effective SHM System for Additive Manufactured Components

    Directory of Open Access Journals (Sweden)

    Michaël F. Hinderdael

    2016-01-01

    Full Text Available Additive manufactured components have a different metallurgic structure and are more prone to fatigue cracks than conventionally produced metals. In earlier papers, an effective Structural Health Monitoring solution was presented to detect fatigue cracks in additive manufactured components. Small subsurface capillaries are embedded in the structure and pressurized (vacuum or overpressure. A crack that initiated at the component’s surface will propagate towards the capillary and finally breach it. One capillary suffices to inspect a large area of the component, which makes it interesting to locate the crack on the basis of the pressure measurements. Negative pressure waves (NPW arise from the abrupt encounter of high pressure fluid with low pressure fluid and can serve as a basis to locate the crack. A test set-up with a controllable leak valve was built to investigate the feasibility of using NPW to localize a leak in closed tubes with small lengths. Reflections are expected to occur at the ends of the tube, possibly limiting the localization accuracy. In this paper, the results of the tests on the test set-up are reported. It will be shown that the crack could be localized with high accuracy (millimeter accuracy which proves the concept of crack localization on basis of NPW in a closed tube of small length.

  18. Dynamics and thermal sensitivity of ballistic and non-ballistic feeding in salamanders.

    Science.gov (United States)

    Deban, Stephen M; Scales, Jeffrey A

    2016-02-01

    Low temperature reduces the performance of muscle-powered movements, but in movements powered by elastic recoil mechanisms, this effect can be mitigated and performance can be increased. To better understand the morphological basis of high performance and thermal robustness of elastically powered movements, we compared feeding dynamics at a range of temperatures (5-25°C) in two species of terrestrial plethodontid salamanders, Plethodon metcalfi and Ensatina eschscholtzii, which differ in tongue muscle architecture and the mechanism of tongue projection. We found that Ensatina is capable of ballistic projection with a mean muscle mass-specific power of 2100 W kg(-1), revealing an elastic mechanism. Plethodon, in contrast, projected its tongue non-ballistically with a mean power of only 18 W kg(-1), indicating it is muscle powered. Ensatina projected its tongue significantly farther than Plethodon and with dynamics that had significantly lower thermal sensitivity at temperatures below 15°C. These performance differences were correlated with morphological differences, namely elongated collagenous aponeuroses in the projector muscle of Ensatina as compared with Plethodon, which are likely the site of energy storage, and the absence in Ensatina of projector muscle fibers attaching to the tongue skeleton that allows projection to be truly ballistic. These findings demonstrate that, in these otherwise similar species, the presence in one species of elaborated connective tissue in series with myofibers confers not only 10-fold greater absolute performance but also greater thermal robustness of performance. We conclude that changes in muscle and connective tissue architecture are sufficient to alter significantly the mechanics, performance and thermal robustness of musculoskeletal systems.

  19. CFD Simulations of the Supersonic Inflatable Aerodynamic Decelerator (SIAD) Ballistic Range Tests

    Science.gov (United States)

    Brock, Joseph; Stern, Eric; Wilder, Michael

    2017-01-01

    A series of ballistic range tests were performed on a scaled model of the Supersonic Flight Demonstration Test (SFDT) intended to test the Supersonic Inflatable Aerodynamic Decelerator (SIAD) geometry. The purpose of these experiments were to provide aerodynamic coefficients of the vehicle to aid in mission and vehicle design. The experimental data spans the moderate Mach number range, $3.8-2.0$, with a total angle of attack ($alpha_T$) range, $10o-20o$. These conditions are intended to span the Mach-$alpha$ space for the majority of the SFDT experiment. In an effort to validate the predictive capabilities of Computational Fluid Dynamics (CFD) for free-flight aerodynamic behavior, numerical simulations of the ballistic range experiment are performed using the unstructured finite volume Navier-Stokes solver, US3D. Comparisons to raw vehicle attitude, and post-processed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data gives further insights into dynamic flow coupling leading to a potential mechanism for dynamic instability.

  20. Equation of State of Ballistic Gelatin

    Science.gov (United States)

    2008-06-23

    del’agitation thermique . Ann. Phys. (Paris) 17, 88 (1922). 4. Gross, E., Change of wave-length of light due to elastic heat waves at scattering in liquids...124, 14502 (2006). 17 8. Sandercock, J. R., Trends in Brillouin-Scattering - Studies of Opaque Materials, Supported Films, and Central Modes, in

  1. The Role of Sub-Target in the Transversely Excited Atmospheric Pressure CO 2 Laser-Induced Shock-Wave Plasma

    Science.gov (United States)

    Suliyanti, Maria; Hedwig, Rinda; Kurniawan, Hendrik; Kagawa, Kiichiro

    1998-12-01

    A transversely excited atmospheric pressure (TEA) CO2 laser pulse (50 mJ, 100 ns) was focused on silicon grease which is painted on a copper plate as a subtarget with a power density of 6 GW/cm2 under reduced pressure. The comparison of the characteristics of the induced laser plasma between two cases, with subtarget and without subtarget was made. It is proved that the emission spectrum assigned to the silicon atom can be detected only for the case with the subtarget. It is also proved that in the absence of the subtarget, the gushing speed of the atom is very low, while for the case with subtarget, the gushing speed of atoms becomes very fast. It is shown that the setting of subtarget is very effective for producing laser-induced shock wave plasma and it is very effective for the realize quantitative analysis of a soft material.

  2. Superconducting Graphene Nanodevices in Ballistic Transport Regime

    Science.gov (United States)

    Chen, Yu-An; Wang, Joel I.-Jan; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo; Pablo Jarillo-Herrero's Group Team

    2013-03-01

    Superconductivity carried by Dirac fermions can be realized through induced superconductivity in grapheme. Observation of novel phenomena anticipated by theories requires graphene devices with low disorder whereas the carrier transport is ballistic. Current fabrication procedures to make graphene devices with low disorder like suspension or ultra-flat substrates all call for certain kinds of annealing to remove organic residues derived from the fabrication process. Applying these methods to superconducting devices can be challenging since the transparency at the graphene/superconductor interface will be destroyed. Here we present a method to do dry transfer of patterned hexagonal Boron Nitride (hBN) flakes onto graphene. The ultra flatness and lack of dangling bond in the boron nitride substrate reduces the disorder in graphene, and the top layer hBN can protect the graphene from contamination in the nanofabrication procedures and yield the geometry desired for different experimental exploration. National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan

  3. Allegany Ballistics Lab: sensor test target system

    Science.gov (United States)

    Eaton, Deran S.

    2011-06-01

    Leveraging the Naval Surface Warfare Center, Indian Head Division's historical experience in weapon simulation, Naval Sea Systems Command commissioned development of a remote-controlled, digitally programmable Sensor Test Target as part of a modern, outdoor hardware-in-the-loop test system for ordnance-related guidance, navigation and control systems. The overall Target system design invokes a sciences-based, "design of automated experiments" approach meant to close the logistical distance between sensor engineering and developmental T&E in outdoor conditions over useful real world distances. This enables operating modes that employ broad spectrum electromagnetic energy in many a desired combination, variably generated using a Jet Engine Simulator, a multispectral infrared emitter array, optically enhanced incandescent Flare Simulators, Emitter/Detector mounts, and an RF corner reflector kit. As assembled, the recently tested Sensor Test Target prototype being presented can capably provide a full array of useful RF and infrared target source simulations for RDT&E use with developmental and existing sensors. Certain Target technologies are patent pending, with potential spinoffs in aviation, metallurgy and biofuels processing, while others are variations on well-established technology. The Sensor Test Target System is planned for extended installation at Allegany Ballistics Laboratory (Rocket Center, WV).

  4. Ballistic spin transport in exciton gases

    Science.gov (United States)

    Kavokin, A. V.; Vladimirova, M.; Jouault, B.; Liew, T. C. H.; Leonard, J. R.; Butov, L. V.

    2013-11-01

    Traditional spintronics relies on spin transport by charge carriers, such as electrons in semiconductor crystals. The challenges for the realization of long-range electron spin transport include rapid spin relaxation due to electron scattering. Scattering and, in turn, spin relaxation can be effectively suppressed in excitonic devices where the spin currents are carried by electrically neutral bosonic quasiparticles: excitons or exciton-polaritons. They can form coherent quantum liquids that carry spins over macroscopic distances. The price to pay is a finite lifetime of the bosonic spin carriers. We present the theory of exciton ballistic spin transport which may be applied to a range of systems supporting bosonic spin transport, in particular to indirect excitons in coupled quantum wells. We describe the effect of spin-orbit interaction for the electron and the hole on the exciton spin, account for the Zeeman effect induced by external magnetic fields and long-range and short-range exchange splittings of the exciton resonances. We also consider exciton transport in the nonlinear regime and discuss the definitions of the exciton spin current, polarization current, and spin conductivity.

  5. Effect of modest salt reduction on blood pressure, urinary albumin, and pulse wave velocity in white, black, and Asian mild hypertensives.

    Science.gov (United States)

    He, Feng J; Marciniak, Maciej; Visagie, Elisabeth; Markandu, Nirmala D; Anand, Vidya; Dalton, R Neil; MacGregor, Graham A

    2009-09-01

    A reduction in salt intake lowers blood pressure. However, most previous trials were in whites with few in blacks and Asians. Salt reduction may also reduce other cardiovascular risk factors (eg, urinary albumin excretion, arterial stiffness). However, few well-controlled trials have studied these effects. We carried out a randomized double-blind crossover trial of salt restriction with slow sodium or placebo, each for 6 weeks, in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. From slow sodium to placebo, urinary sodium was reduced from 165+/-58 (+/-SD) to 110+/-49 mmol/24 hours (9.7 to 6.5 g/d salt). With this reduction in salt intake, there was a significant decrease in blood pressure from 146+/-13/91+/-8 to 141+/-12/88+/-9 mm Hg (P<0.001), urinary albumin from 10.2 (IQR: 6.8 to 18.9) to 9.1 (6.6 to 14.0) mg/24 hours (P<0.001), albumin/creatinine ratio from 0.81 (0.47 to 1.43) to 0.66 (0.44 to 1.22) mg/mmol (P<0.001), and carotid-femoral pulse wave velocity from 11.5+/-2.3 to 11.1+/-1.9 m/s (P<0.01). Subgroup analysis showed that the reductions in blood pressure and urinary albumin/creatinine ratio were significant in all groups, and the decrease in pulse wave velocity was significant in blacks only. These results demonstrate that a modest reduction in salt intake, approximately the amount of the current public health recommendations, causes significant falls in blood pressure in all 3 ethnic groups. Furthermore, it reduces urinary albumin and improves large artery compliance. Although both could be attributable to the falls in blood pressure, they may carry additional benefits on reducing cardiovascular disease above that obtained from the blood pressure falls alone.

  6. Ballistic Missile Defense Glossary Version 3.0.

    Science.gov (United States)

    2007-11-02

    pulsed electro- magnetic radiation. A thin layer of the object’s surface violently and rapidly boils off; the resulting vapor suddenly exerts pressure...Standards Institute. The ratio of the power available at the terminals of an antenna to the incident power density of a plane wave from the direction...resultant presentation to become a random series of tonal impressions. Execution of acquisition strategy to convert some parts or systems components from

  7. Pressure dependency of aortic pulse wave velocity in vivo is not affected by vasoactive substances that alter aortic wall tension ex vivo.

    Science.gov (United States)

    Butlin, Mark; Lindesay, George; Viegas, Kayla D; Avolio, Alberto P

    2015-05-15

    Aortic stiffness, a predictive parameter in cardiovascular medicine, is blood pressure dependent and experimentally requires isobaric measurement for meaningful comparison. Vasoactive drug administration to change peripheral resistance and blood pressure allows such isobaric comparison but may alter large conduit artery wall tension, directly changing aortic stiffness. This study quantifies effects of sodium nitroprusside (SNP, vasodilator) and phenylephrine (PE, vasoconstrictor) on aortic stiffness measured by aortic pulse wave velocity (aPWV) assessed by invasive pressure catheterization in anaesthetized Sprague-Dawley rats (n = 7). This was compared with nondrug-dependent alteration of blood pressure through reduced venous return induced by partial vena cava occlusion. In vivo drug concentration was estimated by modeling clearance rates. Ex vivo responses of excised thoracic and abdominal aortic rings to drugs was measured using myography. SNP administration did not alter aPWV compared with venous occlusion (P = 0.21-0.87). There was a 5% difference in aPWV with PE administration compared with venous occlusion (P arteries in vivo. However, similar drug concentrations affect aortic ring wall tension ex vivo. Future studies investigating in vivo and ex vivo kinetics will need to elucidate mechanisms for this marked difference.

  8. Lower bounds for ballistic current and noise in non-equilibrium quantum steady states

    Directory of Open Access Journals (Sweden)

    Benjamin Doyon

    2015-03-01

    Full Text Available Let an infinite, homogeneous, many-body quantum system be unitarily evolved for a long time from a state where two halves are independently thermalized. One says that a non-equilibrium steady state emerges if there are nonzero steady currents in the central region. In particular, their presence is a signature of ballistic transport. We analyze the consequences of the current observable being a conserved density; near equilibrium this is known to give rise to linear wave propagation and a nonzero Drude peak. Using the Lieb–Robinson bound, we derive, under a certain regularity condition, a lower bound for the non-equilibrium steady-state current determined by equilibrium averages. This shows and quantifies the presence of ballistic transport far from equilibrium. The inequality suggests the definition of “nonlinear sound velocities”, which specialize to the sound velocity near equilibrium in non-integrable models, and “generalized sound velocities”, which encode generalized Gibbs thermalization in integrable models. These are bounded by the Lieb–Robinson velocity. The inequality also gives rise to a bound on the energy current noise in the case of pure energy transport. We show that the inequality is satisfied in many models where exact results are available, and that it is saturated at one-dimensional criticality.

  9. Improvement of Interior Ballistic Performance Utilizing Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Hazem El Sadek

    2014-01-01

    Full Text Available This paper investigates the interior ballistic propelling charge design using the optimization methods to select the optimum charge design and to improve the interior ballistic performance. The propelling charge consists of a mixture propellant of seven-perforated granular propellant and one-hole tubular propellant. The genetic algorithms and some other evolutionary algorithms have complex evolution operators such as crossover, mutation, encoding, and decoding. These evolution operators have a bad performance represented in convergence speed and accuracy of the solution. Hence, the particle swarm optimization technique is developed. It is carried out in conjunction with interior ballistic lumped-parameter model with the mixture propellant. This technique is applied to both single-objective and multiobjective problems. In the single-objective problem, the optimization results are compared with genetic algorithm and the experimental results. The particle swarm optimization introduces a better performance of solution quality and convergence speed. In the multiobjective problem, the feasible region provides a set of available choices to the charge’s designer. Hence, a linear analysis method is adopted to give an appropriate set of the weight coefficients for the objective functions. The results of particle swarm optimization improved the interior ballistic performance and provided a modern direction for interior ballistic propelling charge design of guided projectile.

  10. Transition to ballistic regime for heat transport in helium II

    Energy Technology Data Exchange (ETDEWEB)

    Sciacca, Michele, E-mail: michele.sciacca@unipa.it [Dipartimento Scienze Agrarie e Forestali, Università degli studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Sellitto, Antonio, E-mail: ant.sellitto@gmail.com [Dipartimento di Matematica, Informatica ed Economia, Università della Basilicata, Campus Macchia Romana, 85100 Potenza (Italy); Jou, David, E-mail: david.jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)

    2014-07-04

    The size-dependent and flux-dependent effective thermal conductivity of narrow capillaries filled with superfluid helium is analyzed from a thermodynamic continuum perspective. The classical Landau evaluation of the effective thermal conductivity of quiescent superfluid, or the Gorter–Mellinck regime of turbulent superfluids, is extended to describe the transition to ballistic regime in narrow channels wherein the radius R is comparable to (or smaller than) the phonon mean-free path ℓ in superfluid helium. To do so, we start from an extended equation for the heat flux incorporating non-local terms, and take into consideration a heat slip flow along the walls of the tube. This leads from an effective thermal conductivity proportional to R{sup 2} (Landau regime) to another one proportional to Rℓ (ballistic regime). We consider two kinds of flows: along cylindrical pipes and along two infinite parallel plates. - Highlights: • Heat transport in counterflow helium in the ballistic regime. • The one-fluid model based on the Extended Thermodynamics is used. • The transition from the Landau regime to the ballistic regime. • The transition from quantum turbulence to ballistic regime.

  11. Using Hertzian Indentation to Understand the Strength and Ballistic Resistance of Silicon Carbide

    Energy Technology Data Exchange (ETDEWEB)

    Holmquist, T J [Network Computing Services, Inc., Minneapolis; Wereszczak, Andrew A [ORNL

    2010-01-01

    This article presents an initial evaluation of the usefulness of spherical or Hertzian indentation for the determination and/or validation of constitutive models and for a potential link to ballistic resistance (interface defeat). Recent advancements in producing more confident elevated stress levels in Hertzian indentation make the usefulness of this test much more feasible. There are very few experimental techniques that can produce the high stresses, strains, and pressures produced in Hertzian indentation tests. Additionally, they are also relatively simple, repeatable, timely, and inexpensive. There is still the disadvantage that the stresses, strains, and pressures are not explicit outputs of the experiments requiring the constitutive response to be inferred by performing computations and comparing the computed force-deflection results to the experiment. Preliminary results indicate that Hertzian indentation can be used to help define the constitutive response but it is still uncertain if it can be used to rank a ceramic's ability to produce interface defeat.

  12. Relationship between Ballistic Coefficient and Static Mechanical Properties for Armor Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The relationship between the ballistic coefficient and the static mechanical properties of armor materials was studied. The results show that the ballistic coefficient is determined by the strength, hardness and the toughness of materials. According to the Martel rule, the equation of the relationship between ballistic coefficient and static mechanical properties satisfies the following formula: . From the mixture law of composite, the prerequisite, for which ballistic coefficient has maximum to reinforcement volume fraction, is obtained by the following equation: .

  13. Novel formulations of ballistic gelatin. 1. Rheological properties.

    Science.gov (United States)

    Zecheru, Teodora; Său, Ciprian; Lăzăroaie, Claudiu; Zaharia, Cătălin; Rotariu, Traian; Stănescu, Paul-Octavian

    2016-06-01

    Ballistic gelatin is the simulant of the human body during field tests in forensics and other related fields, due to its physical and mechanical similarities to human trunk and organs. Since the ballistic gelatin used in present has important issues to overcome, an alternative approach is the use of gelatin-polymer composites, where a key factor is the insertion of biocompatible materials, which replicate accurately the human tissues. In order to be able to obtain an improved material in terms of mechanical performances by an easy industrial-scale technology, before the verification of the ballistic parameters by shooting in agreement with military standards, one of the best and cheapest solutions is to perform a thorough check of their rheological properties, in standard conditions.

  14. ["Piggyback" shot: ballistic parameters of two simultaneously discharged airgun pellets].

    Science.gov (United States)

    Frank, Matthias; Schönekess, Holger C; Grossjohann, Rico; Ekkernkamp, Axel; Bockholdt, Britta

    2014-01-01

    Green and Good reported an uncommon case of homicide committed with an air rifle in 1982 (Am. J. Forensic Med. Pathol. 3: 361-365). The fatal wound was unusual in that two airgun pellets were loaded in so-called "piggyback" fashion into a single shot air rifle. Lack of further information on the ballistic characteristics of two airgun pellets as opposed to one conventionally loaded projectile led to this investigation. The mean kinetic energy (E) of the two pellets discharged in "piggyback" fashion was E = 3.6 J and E = 3.4 J, respectively. In comparison, average kinetic energy values of E = 12.5 J were calculated for conventionally discharged single diabolo pellets. Test shots into ballistic soap confirmed the findings of a single entrance wound as reported by Green and Good. While the ballistic background of pellets discharged in "piggyback" fashion could be clarified, the reason behind this mode of shooting remains unclear.

  15. Ballistic spin filtering across the ferromagnetic-semiconductor interface

    Directory of Open Access Journals (Sweden)

    Y.H. Li

    2012-03-01

    Full Text Available The ballistic spin-filter effect from a ferromagnetic metal into a semiconductor has theoretically been studied with an intention of detecting the spin polarizability of density of states in FM layer at a higher energy level. The physical model for the ballistic spin filtering across the interface between ferromagnetic metals and semiconductor superlattice is developed by exciting the spin polarized electrons into n-type AlAs/GaAs superlattice layer at a much higher energy level and then ballistically tunneling through the barrier into the ferromagnetic film. Since both the helicity-modulated and static photocurrent responses are experimentally measurable quantities, the physical quantity of interest, the relative asymmetry of spin-polarized tunneling conductance, could be extracted experimentally in a more straightforward way, as compared with previous models. The present physical model serves guidance for studying spin detection with advanced performance in the future.

  16. Design and Manufacturing Process for a Ballistic Missile

    Directory of Open Access Journals (Sweden)

    Zaharia Sebastian Marian

    2016-12-01

    Full Text Available Designing a ballistic missile flight depends on the mission and the stress to which the missile is subject. Missile’s requests are determined by: the organization of components; flight regime type, engine configuration and aerodynamic performance of the rocket flight. In this paper has been developed a ballistic missile with a smooth fuselage type, 10 control surfaces, 8 directional surfaces for cornering execution, 2 for maneuvers of execution to change the angle of incidence and 4 stabilizers direction. Through the technology of gluing and clamping of the shell and the use of titanium components, mass of ballistic missile presented a significant decrease in weight and a structure with high strength.

  17. 深圳地铁11号线隧道空气压力波研究%Study on Air Pressure Waves in Tunnels on Shenzhen Metro Line 11

    Institute of Scientific and Technical Information of China (English)

    张海天; 陈健

    2011-01-01

    The article proposes pressure comfort standards in high-speed metro tunnels. By using the tunnel pressure wave analysis software ThermoTun, authors analyzed tunnel pressure waves and comfort of pressure considering different section design for tunnels on Shenzhen metro line 11. They also put forward design proposals for tunnel pressure relief system and tunnel profile.%分析并提出高速地铁隧道压力舒适度标准.采用隧道压力波分析软件ThermoTun,对深圳地铁11号线隧道段不同断面设计情况下的压力波及压力舒适度进行分析,提出对隧道泄压系统及隧道断面的设计建议.

  18. Geometrical optimization of a local ballistic magnetic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kanda, Yuhsuke; Hara, Masahiro [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Nomura, Tatsuya [Advanced Electronics Research Division, INAMORI Frontier Research Center, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kimura, Takashi [Advanced Electronics Research Division, INAMORI Frontier Research Center, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

    2014-04-07

    We have developed a highly sensitive local magnetic sensor by using a ballistic transport property in a two-dimensional conductor. A semiclassical simulation reveals that the sensitivity increases when the geometry of the sensor and the spatial distribution of the local field are optimized. We have also experimentally demonstrated a clear observation of a magnetization process in a permalloy dot whose size is much smaller than the size of an optimized ballistic magnetic sensor fabricated from a GaAs/AlGaAs two-dimensional electron gas.

  19. Research on ballistic missile laser SIMU error propagation mechanism

    Institute of Scientific and Technical Information of China (English)

    Wei Shihui; Xiao Longxu

    2008-01-01

    It is necessary that the laser inertial system is used to further improve the fire accuracy and quick reaction capability in the ballistic missile strapdown inertial navigation system. According to the guidance con-trolling method and the output and error model of ballistic missile laser SIMU, the mathematical model of error propagation mechanism is set up and any transfer environmental function of error coefficient that affects the fire accuracy is deduced. Also, the missile longitudinal/lateral impact point is calculated using MATLAB. These estab-lish the technical foundation for further researching the dispersion characteristics of impact point and reducing the laser guidance error.

  20. Advanced Computer Science on Internal Ballistics of Solid Rocket Motors

    Science.gov (United States)

    Shimada, Toru; Kato, Kazushige; Sekino, Nobuhiro; Tsuboi, Nobuyuki; Seike, Yoshio; Fukunaga, Mihoko; Daimon, Yu; Hasegawa, Hiroshi; Asakawa, Hiroya

    In this paper, described is the development of a numerical simulation system, what we call “Advanced Computer Science on SRM Internal Ballistics (ACSSIB)”, for the purpose of improvement of performance and reliability of solid rocket motors (SRM). The ACSSIB system is consisting of a casting simulation code of solid propellant slurry, correlation database of local burning-rate of cured propellant in terms of local slurry flow characteristics, and a numerical code for the internal ballistics of SRM, as well as relevant hardware. This paper describes mainly the objectives, the contents of this R&D, and the output of the fiscal year of 2008.

  1. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    Science.gov (United States)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  2. Solid propellant rocket motor internal ballistics performance variation analysis, phase 3

    Science.gov (United States)

    Sforzini, R. H.; Foster, W. A., Jr.; Murph, J. E.; Adams, G. W., Jr.

    1977-01-01

    Results of research aimed at improving the predictability of off nominal internal ballistics performance of solid propellant rocket motors (SRMs) including thrust imbalance between two SRMs firing in parallel are reported. The potential effects of nozzle throat erosion on internal ballistic performance were studied and a propellant burning rate low postulated. The propellant burning rate model when coupled with the grain deformation model permits an excellent match between theoretical results and test data for the Titan IIIC, TU455.02, and the first Space Shuttle SRM (DM-1). Analysis of star grain deformation using an experimental model and a finite element model shows the star grain deformation effects for the Space Shuttle to be small in comparison to those of the circular perforated grain. An alternative technique was developed for predicting thrust imbalance without recourse to the Monte Carlo computer program. A scaling relationship used to relate theoretical results to test results may be applied to the alternative technique of predicting thrust imbalance or to the Monte Carlo evaluation. Extended investigation into the effect of strain rate on propellant burning rate leads to the conclusion that the thermoelastic effect is generally negligible for both steadily increasing pressure loads and oscillatory loads.

  3. Monte Carlo Uncertainty Quantification Using Quasi-1D SRM Ballistic Model

    Directory of Open Access Journals (Sweden)

    Davide Viganò

    2016-01-01

    Full Text Available Compactness, reliability, readiness, and construction simplicity of solid rocket motors make them very appealing for commercial launcher missions and embarked systems. Solid propulsion grants high thrust-to-weight ratio, high volumetric specific impulse, and a Technology Readiness Level of 9. However, solid rocket systems are missing any throttling capability at run-time, since pressure-time evolution is defined at the design phase. This lack of mission flexibility makes their missions sensitive to deviations of performance from nominal behavior. For this reason, the reliability of predictions and reproducibility of performances represent a primary goal in this field. This paper presents an analysis of SRM performance uncertainties throughout the implementation of a quasi-1D numerical model of motor internal ballistics based on Shapiro’s equations. The code is coupled with a Monte Carlo algorithm to evaluate statistics and propagation of some peculiar uncertainties from design data to rocker performance parameters. The model has been set for the reproduction of a small-scale rocket motor, discussing a set of parametric investigations on uncertainty propagation across the ballistic model.

  4. A computational study of influence of helmet padding materials on the human brain under ballistic impacts.

    Science.gov (United States)

    Salimi Jazi, Mehdi; Rezaei, Asghar; Karami, Ghodrat; Azarmi, Fardad; Ziejewski, Mariusz

    2014-01-01

    The results of a computational study of a helmeted human head are presented in this paper. The focus of the work is to study the effects of helmet pad materials on the level of acceleration, inflicted pressure and shear stress in a human brain model subjected to a ballistic impact. Four different closed cell foam materials, made of expanded polystyrene and expanded polypropylene, are examined for the padding material. It is assumed that bullets cannot penetrate the helmet shell. Finite element modelling of the helmet, padding system, head and head components is used for this dynamic nonlinear analysis. Appropriate contacts and conditions are applied between the different components of the head, as well as between the head and the pads, and the pads and the helmet. Based on the results of simulations in this work, it is concluded that the stiffness of the foam has a prominent role in reducing the level of the transferred load to the brain. A pad that is less stiff is more efficient in absorbing the impact energy and reducing the sudden acceleration of the head and consequently lowers the brain injury level. Using the pad with the least stiffness, the influence of the angle of impacts as well as the locations of the ballistic strike is studied.

  5. The experimental studies on electrical conductivities and P-wave velocities of anorthosite at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    白利平; 杜建国; 刘巍; 周文戈

    2002-01-01

    Results of P-wave velocity (vP) and electrical conductivity measurements on anorthosite are presented from room temperature to 880 (C at 1.0 GPa using ultrasonic transmission technique and impedance spectra technique respectively. The experiments show that the P-wave velocities in anorthosite decrease markedly above 680 (C following the dehydration of hydrous minerals in the rock, and the complex impedances collected from 12 Hz to 105 Hz only indicate the grain interior conduction mechanism at 1.0 GPa, from 410 (C to 750 (C. Because the fluids in the rock have not formed an interconnected network, the dehydration will not pronouncedly enhance the electrical conductivity and change the electrical conduction mechanism. It is concluded that the formation and evolution of the low-velocity zones and high-conductivity layers in the crust may have no correlations, and the dehydration can result in the formation of the low-velocity zones, but cannot simultaneously result in the high-conductivity layers.

  6. Memory Effects on Nonlinear Temperature and Pressure Wave Propagation in the Boundary between Two Fluid-Saturated Porous Rocks

    OpenAIRE

    Garra, R.; Salusti, E.; Droghei, R.

    2015-01-01

    The evolution of strong transients of temperature and pressure in two adjacent fluid-saturated porous rocks is described by a Burgers equation in an early model of Natale and Salusti (1996). We here consider the effect of a realistic intermediate region between the two media and infer how transient processes can also happen, such as chemical reactions, diffusion of fine particles, and filter cake formations. This suggests enlarging our analysis and taking into account not only punctual quanti...

  7. 体检人群脉搏波传导速度与动态血压监测指标的相关性研究%Relationship between pulse wave velocity and parameters from ambulatory blood pressure monitoring

    Institute of Scientific and Technical Information of China (English)

    李曦; 胡荣; 芦燕玲; 于利群; 周生来

    2013-01-01

    目的:脉搏波传导速度与动态血压监测指标的关系.方法:行动态血压监测的体检者582例,根据血压水平分为正常血压组、血压正常高值组和高血压组,分析脉搏波传导速度与动态血压各指标之间的关系.结果:三组间动态血压各指标显著增高;颈股脉搏波传导速度三组间差异有统计学意义(P<0.05);高血压组颈桡脉搏波传导速度显著高于血压正常组.Pearson相关性分析:颈桡脉搏波传导速度与24 h平均SBP/DBP、白天平均SBP/DBP、夜间平均DBP、白天DBP负荷、夜间DBP负荷均呈正相关.颈股脉搏波传导速度与24h平均SBP、白天/夜间平均SBP、白天/夜间SBP负荷、白天SBP变化标准差均呈正相关.多元线性回归发现颈股脉搏波传导速度与24h平均SBP独立相关,颈桡脉搏波传导速度与白天平均DBP独立相关.结论:随血压水平程度升高,脉搏波传导速度明显增快.%Objective:To investigate relationship between pulse wave velocity and parameters from ambulatory blood pressure monitoring in examination persons.Methods:The 582 examination persons were taken ambulatory blood pressure monitoring and pulse wave velocity,the parameters were analyzed according blood pressure level.Results:The parameters from ambulatory blood pressure monitoring increase obviously in 3 groups.The carotid-femoral pulse wave velocity increase obviously in 3 groups.The carotid-radial pulse wave velocity were higher in hypertension group than normotensive.After analysis of pearson correlation,The carotidradial pulse wave velocity positively correlated with the mean 24h blood pressure,daytime mean blood pressure,night diastolic blood pressure,daytime diastolic blood pressure load,night diastolic blood pressure load.The carotid-femoral pulse wave velocity positively correlated with 24h systolic blood pressure,daytime and night systolic blood pressure,daytime and night systolic blood pressure load,daytime systolic blood

  8. Magnetic field effects on the charge-density-wave and superconducting states in pressurized {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kartsovnik, M.V., E-mail: mark.kartsovnik@wmi.badw.de [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Biberacher, W.; Andres, D.; Jakob, S.; Kunz, M.; Neumaier, K. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Mueller, H. [European Synchrotron Radiation Facility, 38043 Grenoble (France); Kushch, N.D. [Institute of Problems of Chemical Physics, 142432 Chernogolovka (Russian Federation)

    2012-06-01

    Coupling of a magnetic field to the orbital and spin degrees of freedom of charge carriers is well known to cause suppression of superconductivity. While the orbital pair-breaking generally dominates in conventional superconductors, the Pauli paramagnetic effect may become important in some heavy fermion compounds or strongly anisotropic materials such as high-T{sub c} or organic superconductors. The same two mechanisms are predicted to be operative also in the case of charge-density-wave (CDW) ordering. However, now they lead to opposite effects: the paramagnetic coupling weakens the CDW interaction whereas the orbital coupling enhances it in a system with an imperfectly nested Fermi surface. Here we report on the experimental evidence of both kinds of magnetic field effects on the CDW and superconducting instabilities in the layered organic metal {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} under quasihydrostatic pressure.

  9. Magnetic field effects on the charge-density-wave and superconducting states in pressurized α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Kartsovnik, M. V.; Biberacher, W.; Andres, D.; Jakob, S.; Kunz, M.; Neumaier, K.; Müller, H.; Kushch, N. D.

    2012-06-01

    Coupling of a magnetic field to the orbital and spin degrees of freedom of charge carriers is well known to cause suppression of superconductivity. While the orbital pair-breaking generally dominates in conventional superconductors, the Pauli paramagnetic effect may become important in some heavy fermion compounds or strongly anisotropic materials such as high-Tc or organic superconductors. The same two mechanisms are predicted to be operative also in the case of charge-density-wave (CDW) ordering. However, now they lead to opposite effects: the paramagnetic coupling weakens the CDW interaction whereas the orbital coupling enhances it in a system with an imperfectly nested Fermi surface. Here we report on the experimental evidence of both kinds of magnetic field effects on the CDW and superconducting instabilities in the layered organic metal α-(BEDT-TTF)2KHg(SCN)4 under quasihydrostatic pressure.

  10. Birch's law for high-pressure metals and ionic solids: Sound velocity data comparison between shock wave experiments and recent diamond anvil cell experiments

    Science.gov (United States)

    Boness, David A.; Ware, Lucas

    2017-01-01

    Sound velocity-density systematics has long been a fruitful way to take shock wave measurements on elements, alloys, oxides, rocks, and other materials, and allow reasonable extrapolation to densities found deep in the Earth. Recent detection of super-Earths has expanded interest in terrestrial planetary interiors to an even greater range of materials and pressures. Recent published diamond anvil cell (DAC) experimental measurements of sound velocities in iron and iron alloys, relevant to planetary cores, are inconsistent with each other with regard to the validity of Birch's Law, a linear relation between sound velocity and density. We examine the range of validity of Birch's Law for several shocked metallic elements, including iron, and shocked ionic solids and make comparisons to the recent DAC data.

  11. Relation between burnout and differential pressure fluctuation characteristics by the disturbance waves near the flow obstacle in a vertical annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shoji; Fukano, Tohru [Kyushu Univ., Graduate School of Engineering, Fukuoka (Japan)

    2002-07-01

    If a flow obstruction such as a spacer is set in a boiling two-phase flow within an annular channel, the inner tube of which is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some cases the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. But the thermo-fluid dynamic mechanism to cause burnout near the spacer is not still clear. In the present paper we discuss temperature fluctuation characteristics in relation to the change of the differential pressure across the spacer caused by the passing of the disturbance waves in case that the burnout generates. (author)

  12. The ballistic performance of the bombard Mons Meg

    Directory of Open Access Journals (Sweden)

    Ian Lewtas

    2016-04-01

    Full Text Available The bombard Mons Meg, located in Edinburgh Castle, with a diameter of 19 inches (48 cm, was one of the largest calibre cannons ever built. Constructed in 1449 and presented to King James II of Scotland in 1454, Mons Meg was used in both military and ceremonial roles in Scotland until its barrel burst in 1680. This paper examines the history, internal, external and terminal ballistics of the cannon and its shot. The likely muzzle velocity was estimated by varying the propellant type and the cannon profile was investigated to identify weak spots in the design that may have led to its failure. Using the muzzle velocity calculated from the internal ballistics, simulations were performed with granite and sandstone shot for varying launch angle and ground temperature. The likely trajectory and range of the cannonballs are described. The internal and external ballistics informed the initial conditions of the terminal ballistic impact scenarios. The performance of the cannonball against both period and modern targets, in the form of a pseudo-castle wall and a monolithic concrete target, respectively, were simulated and are presented and discussed.

  13. The ballistic performance of the bombard Mons Meg

    Institute of Scientific and Technical Information of China (English)

    Ian LEWTAS; Rachael MCALISTER; Adam WALLIS; Clive WOODLEY; Ian CULLIS

    2016-01-01

    The bombard Mons Meg, located in Edinburgh Castle, with a diameter of 19 inches (48 cm), was one of the largest calibre cannons ever built. Constructed in 1449 and presented to King James II of Scotland in 1454, Mons Meg was used in both military and ceremonial roles in Scotland until its barrel burst in 1680. This paper examines the history, internal, external and terminal ballistics of the cannon and its shot. The likely muzzle velocity was estimated by varying the propellant type and the cannon profile was investigated to identify weak spots in the design that may have led to its failure. Using the muzzle velocity calculated from the internal ballistics, simulations were performed with granite and sandstone shot for varying launch angle and ground temperature. The likely trajectory and range of the cannonballs are described. The internal and external ballistics informed the initial conditions of the terminal ballistic impact scenarios. The performance of the cannonball against both period and modern targets, in the form of a pseudo-castle wall and a monolithic concrete target, respectively, were simulated and are presented and discussed.

  14. On the Trajectories of Projectiles Depicted in Early Ballistic Woodcuts

    Science.gov (United States)

    Stewart, Sean M.

    2012-01-01

    Motivated by quaint woodcut depictions often found in many late 16th and 17th century ballistic manuals of cannonballs fired in air, a comparison of their shapes with those calculated for the classic case of a projectile moving in a linear resisting medium is made. In considering the asymmetrical nature of such trajectories, the initial launch…

  15. The application of computed tomography in wound ballistics research

    Science.gov (United States)

    Tsiatis, Nick; Moraitis, Konstantinos; Papadodima, Stavroula; Spiliopoulou, Chara; Kelekis, Alexis; Kelesis, Christos; Efstathopoulos, Efstathios; Kordolaimi, Sofia; Ploussi, Agapi

    2015-09-01

    In wound ballistics research there is a relationship between the data that characterize a bullet and the injury resulted after shooting when it perforates the human body. The bullet path in the human body following skin perforation as well as the damaging effect cannot always be predictable as they depend on various factors such as the bullet's characteristics (velocity, distance, type of firearm and so on) and the tissue types that the bullet passes through. The purpose of this presentation is to highlight the contribution of Computed Tomography (CT) in wound ballistics research. Using CT technology and studying virtual “slices” of specific areas on scanned human bodies, allows the evaluation of density and thickness of the skin, the subcutaneous tissue, the muscles, the vital organs and the bones. Density data taken from Hounsfield units can be converted in g/ml by using the appropriate software. By evaluating the results of this study, the anatomy of the human body utilizing ballistic gel will be reproduced in order to simulate the path that a bullet follows. The biophysical analysis in wound ballistics provides another application of CT technology, which is commonly used for diagnostic and therapeutic purposes in various medical disciplines.

  16. Optimal control of the ballistic motion of Airy beams.

    Science.gov (United States)

    Hu, Yi; Zhang, Peng; Lou, Cibo; Huang, Simon; Xu, Jingjun; Chen, Zhigang

    2010-07-01

    We demonstrate the projectile motion of two-dimensional truncated Airy beams in a general ballistic trajectory with controllable range and height. We show that the peak beam intensity can be delivered to any desired location along the trajectory as well as repositioned to a given target after displacement due to propagation through disordered or turbulent media.

  17. Chicxulub High-Altitude Ballistic Ejecta from Central Belize

    Science.gov (United States)

    Pope, K. O.; Ocampo, A. C.

    2000-01-01

    Chicxulub ejecta are found in central Belize, 475 km southeast of the impact crater center. These deposits are ballistic ejecta launched along high-altitude trajectories above the atmosphere and deposited as a discontinuous sheet on the terminal Cretaceous land surface.

  18. Shock Wave Structure in Particulate Composites

    Science.gov (United States)

    Rauls, Michael; Ravichandran, Guruswami

    2015-06-01

    Shock wave experiments are conducted on a particulate composite consisting of a polymethyl methacrylate (PMMA) matrix reinforced by glass beads. Such a composite with an impedance mismatch of 4.3 closely mimics heterogeneous solids of interest such as concrete and energetic materials. The composite samples are prepared using a compression molding process. The structure and particle velocity rise times of the shocks are examined using forward ballistic experiments. Reverse ballistic experiments are used to track how the interface density influences velocity overshoot above the steady state particle velocity. The effects of particle size (0.1 to 1 mm) and volume fraction of glass beads (30-40%) on the structure of the leading shock wave are investigated. It is observed that the rise time increases with increasing particle size and scales linearly for the range of particle sizes considered here. Results from numerical simulations using CTH are compared with experimental results to gain insights into wave propagation in heterogeneous particulate composites.

  19. Pressure and stress waves in a spallation neutron source mercury target generated by high-power proton pulses

    CERN Document Server

    Futakawa, M; Conrad, H; Stechemesser, H

    2000-01-01

    The international ASTE collaboration has performed a first series of measurements on a spallation neutron source target at the Alternating Gradient Synchrotron (AGS) in Brookhaven. The dynamic response of a liquid mercury target hit by high-power proton pulses of about 40 ns duration has been measured by a laser Doppler technique and compared with finite elements calculations using the ABAQUS code. It is shown that the calculation can describe the experimental results for at least the time interval up to 100 mu s after the pulse injection. Furthermore, it has been observed that piezoelectric pressure transducers cannot be applied in the high gamma-radiation field of a spallation target.

  20. Ballistic parameters and trauma potential of pistol crossbows.

    Science.gov (United States)

    Frank, Matthias; Schikorr, Wolfgang; Tesch, Ralf; Werner, Ronald; Hanisch, Steffen; Peters, Dieter; Ekkernkamp, Axel; Bockholdt, Britta; Seifert, Julia

    2013-07-01

    Hand-held pistol crossbows, which are smaller versions of conventional crossbows, have recently increased in popularity. Similar to conventional crossbows, life threatening injuries due to bolts discharged from pistol crossbows are reported in forensic and traumatological literature. While the ballistic background of conventional crossbows is comprehensively investigated, there are no investigations on the characteristic ballistic parameters (draw force, potential energy, recurve factor, kinetic energy, and efficiency) of pistol crossbows. Two hand-held pistol crossbows (Barnett Commando and Mini Cross Bow, rated draw force 362.9 N or 80 lbs) were tested. The maximum draw force was investigated using a dynamic tensile testing machine (TIRAtest 2705, TIRA GmbH). The potential energy was determined graphically by polynomial regression as area under the force-draw curve. External ballistic parameters of the bolts discharged from pistol crossbows were measured using a redundant ballistic speed measurement system (Dual-BMC 21a and Dual-LS 1000, Werner Mehl Kurzzeitmesstechnik). The average maximum draw force was 190.3 and 175.6 N for the Barnett and Mini Cross Bow, respectively. The corresponding total energy expended was 10.7 and 11 J, respectively. The recurve factor was calculated to be 0.705 and 1.044, respectively. Average bolt velocity was measured 43 up to 52 m/s. The efficiency was calculated up to 0.94. To conclude, this work provides the pending ballistic data on this special subgroup of crossbows which operate on a remarkable low kinetic energy level. Furthermore, it demonstrates that the nominal draw force pretended in the sales brochure is grossly exaggerated.

  1. Signs of muscle thixotropy during human ballistic wrist joint movements.

    Science.gov (United States)

    Axelson, H W

    2005-11-01

    A study was conducted on healthy subjects to determine whether voluntary ballistic wrist flexion movements are influenced by immediately preceding conditioning of the forearm muscles. Single rapid wrist flexion movements were made in response to an auditory "Go" signal. Rectified surface EMG was recorded from wrist flexors and extensors, and joint position was measured by a goniometer. The movements were preceded (2-3 s) by four different conditioning routines: 40-s rest (Rest), 10-s voluntary alternating wrist joint flexion and extension movements (Osc), and 10 s of 25 degrees weak isometric wrist extensor (Ext) or flexor contractions (Flex). When subjects made ballistic movements after Osc compared with Rest, peak velocity was higher (P = 0.02) and movement time shorter (P = 0.06), but there was no difference (P = 0.83) in motor reaction time (time between the onset of the first agonist burst and movement onset). If the movements were preceded by Ext compared with Flex, motor reaction time was longer (P = 0.01), indicating a longer electromechanical delay. There were no indications that postconditioning differences in agonist or antagonist muscle activity could explain the results. It was also demonstrated that, after Rest, peak velocity was lower (P < 0.01) for the first than for the second of a series of repetitive ballistic movements. The observations corresponded to results from passive experiments in which the median nerve was electrically stimulated. In conclusion, history-dependent (thixotropic) changes in skeletal muscle resistance seem to have implications for voluntary ballistic wrist movements. The study also provided evidence that muscle conditioning influences the central nervous reaction time preceding ballistic contractions.

  2. High-efficiency generation of pulsed Lyman-α radiation by resonant laser wave mixing in low pressure Kr-Ar mixture.

    Science.gov (United States)

    Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Louchev, Oleg A; Iwasaki, Masahiko; Wada, Satoshi

    2016-04-04

    We report an experimental generation of ns pulsed 121.568 nm Lyman-α radiation by the resonant nonlinear four-wave mixing of 212.556 nm and 845.015 nm radiation pulses providing a high conversion efficiency 1.7x10-3 with the output pulse energy 3.6 μJ achieved using a low pressure Kr-Ar mixture. Theoretical analysis shows that this efficiency is achieved due to the advantage of using (i) the high input laser intensities in combination with (ii) the low gas pressure allowing us to avoid the onset of full-scale discharge in the laser focus. In particular, under our experimental conditions the main mechanism of photoionization caused by the resonant 2-photon 212.556 nm radiation excitation of Kr atoms followed by the 1-photon ionization leads to ≈17% loss of Kr atoms and efficiency loss only by the end of the pulse. The energy of free electrons, generated by 212.556 nm radiation via (2 + 1)-photon ionization and accelerated mainly by 845.015 nm radiation, remains during the pulse below the level sufficient for the onset of full-scale discharge by the electron avalanche. Our analysis also suggests that ≈30-fold increase of 845.015 nm pulse energy can allow one to scale up the L-α radiation pulse energy towards the level of ≈100 μJ.

  3. Low-Pressure Burst-Mode Focused Ultrasound Wave Reconstruction and Mapping for Blood-Brain Barrier Opening: A Preclinical Examination

    Science.gov (United States)

    Xia, Jingjing; Tsui, Po-Hsiang; Liu, Hao-Li

    2016-06-01

    Burst-mode focused ultrasound (FUS) exposure has been shown to induce transient blood-brain barrier (BBB) opening for potential CNS drug delivery. FUS-BBB opening requires imaging guidance during the intervention, yet current imaging technology only enables postoperative outcome confirmation. In this study, we propose an approach to visualize short-burst low-pressure focal beam distribution that allows to be applied in FUS-BBB opening intervention on small animals. A backscattered acoustic-wave reconstruction method based on synchronization among focused ultrasound emission, diagnostic ultrasound receiving and passively beamformed processing were developed. We observed that focal beam could be successfully visualized for in vitro FUS exposure with 0.5–2 MHz without involvement of microbubbles. The detectable level of FUS exposure was 0.467 MPa in pressure and 0.05 ms in burst length. The signal intensity (SI) of the reconstructions was linearly correlated with the FUS exposure level both in-vitro (r2 = 0.9878) and in-vivo (r2 = 0.9943), and SI level of the reconstructed focal beam also correlated with the success and level of BBB-opening. The proposed approach provides a feasible way to perform real-time and closed-loop control of FUS-based brain drug delivery.

  4. Experimental study of the coupling parameters influencing the terminal effects of thoracic blunt ballistic impacts.

    Science.gov (United States)

    Pavier, Julien; Langlet, André; Eches, Nicolas; Prat, Nicolas; Bailly, Patrice; Jacquet, Jean-François

    2015-07-01

    The objective of the study is to better understand how blunt projectile ballistic parameters and material properties influence the events leading to injuries. The present work focuses on lateral thoracic impacts and follows an experimental approach. The projectiles are made with a soft foam nose assembled with a rigid rear plastic part. The dynamic properties of the foams were first determined using the Split Hopkinson Pressure Bar (SHPB) system. The impact forces on a rigid wall were then measured to provide reference load data. Lastly, shots were made on isolated thoraxes of porcine cadavers to investigate the response in the vicinity of the impact (wall displacements, rib accelerations and strains, rib fractures). Results show that the severity of the response appears to be mainly correlated with the impulse and with the pre-impact momentum.

  5. Memory Effects on Nonlinear Temperature and Pressure Wave Propagation in the Boundary between Two Fluid-Saturated Porous Rocks

    Directory of Open Access Journals (Sweden)

    R. Garra

    2015-01-01

    Full Text Available The evolution of strong transients of temperature and pressure in two adjacent fluid-saturated porous rocks is described by a Burgers equation in an early model of Natale and Salusti (1996. We here consider the effect of a realistic intermediate region between the two media and infer how transient processes can also happen, such as chemical reactions, diffusion of fine particles, and filter cake formations. This suggests enlarging our analysis and taking into account not only punctual quantities but also “time averaged” quantities. These boundary effects are here analyzed by using a “memory formalism”; that is, we replace the ordinary punctual time-derivatives with Caputo fractional time-derivatives. We therefore obtain a nonlinear fractional model, whose explicit solution is shown, and finally discuss its geological importance.

  6. Improvement of erectile dysfunction by the active pepide from Urechis unicinctus by high temperature/pressure and ultra - wave assisted lysis in Streptozotocin Induced Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Kang Sup Kim

    Full Text Available ABSTRACT Introduction: We investigate the effect of active peptide from Urechis unicinctus (UU by high temperature/pressure and ultra-wave assisted lysis on erectile dysfunction in streptozotocin-induced diabetic rats. Materials and Methods: Forty 12-week-old Sprague-Dawley rats were used in this study. Diabetes was induced by a one-time intraperitoneal injection of streptozotocin (50mg/kg. One week later, the diabetic rats were randomly divided into four groups: normal control, untreated diabetes control, and groups treated with 100 or 500mg/kg/d UU peptide. Rats were fed with UU peptide by intragastric administration for 8 weeks. After 8 weeks, penile hemodynamic function was evaluated in all groups by measuring the intracavernosal pressure after electrostimulating the cavernous nerve. Nitric oxide (NO and cyclic guanosine monophosphate (cGMP activities were measured and endothelial nitric oxide synthase (eNOS and neuronal NOS (nNOS protein expression was determined by Western blot. Results: Maximum intracavernosal pressure in diabetic control rats decreased significantly compared to normal control rats, and was increased significantly compared to untreated diabetic rats after UU peptide supplementation. Treatment with the higher dose of UU peptide significantly increased the NO and cGMP levels compared with the diabetic control group. Decreased activity and expression eNOS and nNOS were found in the diabetic rats compared with the normal control group. Decreased eNOS and nNOS in diabetic rats were improved by UU peptide administration. Conclusions: Active peptide from UU ameliorates erectile function in a streptozotocin induced diabetic rat model of erectile dysfunction.

  7. Improvement of erectile dysfunction by the active pepide from Urechis unicinctus by high temperature/pressure and ultra - wave assisted lysis in Streptozotocin Induced Diabetic Rats

    Science.gov (United States)

    Kim, Kang Sup; Bae, Woong Jin; Kim, Su Jin; Kang, Kyong-Hwa; Kim, Se-Kwon; Cho, Hyuk Jin; Hong, Sung-Hoo; Lee, Ji Youl; Kim, Sae Woong

    2016-01-01

    ABSTRACT Introduction: We investigate the effect of active peptide from Urechis unicinctus (UU) by high temperature/pressure and ultra-wave assisted lysis on erectile dysfunction in streptozotocin-induced diabetic rats. Materials and Methods: Forty 12-week-old Sprague-Dawley rats were used in this study. Diabetes was induced by a one-time intraperitoneal injection of streptozotocin (50mg/kg). One week later, the diabetic rats were randomly divided into four groups: normal control, untreated diabetes control, and groups treated with 100 or 500mg/kg/d UU peptide. Rats were fed with UU peptide by intragastric administration for 8 weeks. After 8 weeks, penile hemodynamic function was evaluated in all groups by measuring the intracavernosal pressure after electrostimulating the cavernous nerve. Nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) activities were measured and endothelial nitric oxide synthase (eNOS) and neuronal NOS (nNOS) protein expression was determined by Western blot. Results: Maximum intracavernosal pressure in diabetic control rats decreased significantly compared to normal control rats, and was increased significantly compared to untreated diabetic rats after UU peptide supplementation. Treatment with the higher dose of UU peptide significantly increased the NO and cGMP levels compared with the diabetic control group. Decreased activity and expression eNOS and nNOS were found in the diabetic rats compared with the normal control group. Decreased eNOS and nNOS in diabetic rats were improved by UU peptide administration. Conclusions: Active peptide from UU ameliorates erectile function in a streptozotocin induced diabetic rat model of erectile dysfunction. PMID:27564297

  8. Violent breaking wave impacts

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Peregrine, D.H.; Bullock, G.N.

    2009-01-01

    for a homogeneous mixture of incompressible liquid and ideal gas. This enables a numerical description of both trapped air pockets and the propagation of pressure shock waves through the aerated water. An exact Riemann solver is developed to permit a finite-volume solution to the flow model with smallest possible...... local error. The high pressures measured during wave impacts on a breakwater are reproduced and it is shown that trapped air can be compressed to a pressure of several atmospheres. Pressure shock waves, reflected off nearby surfaces such as the seabed, can lead to pressures comparable with those...

  9. Slime mould logical gates: exploring ballistic approach

    CERN Document Server

    Adamatzky, Andrew

    2010-01-01

    Plasmodium of \\emph{Physarum polycephalum} is a single cell visible by unaided eye. On a non-nutrient substrate the plasmodium propagates as a traveling localization, as a compact wave-fragment of protoplasm. The plasmodium-localization travels in its originally predetermined direction for a substantial period of time even when no gradient of chemo-attractants is present. We utilize this property of \\emph{Physarum} localizations to design a two-input two-output Boolean logic gates $ \\to $ and $ \\to $. We verify the designs in laboratory experiments and computer simulations. We cascade the logical gates into one-bit half-adder and simulate its functionality.

  10. The propagation of pressure wave in closed channel filed of periodic alternate corks with the gas–liquid mixture and gas

    Directory of Open Access Journals (Sweden)

    Grigoryan Sh.A.

    2015-09-01

    Full Text Available The propagation of wave in closed channel filed of corks is considered. It is supposed that the discrete structure of corks is periodic. The dispersion equation of the Bloch wave number dependence on wave numbers of corks is derived. It is obtained the frequencies bands of transmitting waves.

  11. Hybrid carbon-glass fiber/toughened epoxy thick composites subject to drop-weight and ballistic impacts

    Science.gov (United States)

    Sevkat, Ercan

    The goals of this study are to investigate the low velocity and ballistic impact response of thick-section hybrid fiber composites at room temperature. Plain-woven S2-Glass and IM7 Graphite fabrics are chosen as fiber materials reinforcing the SC-79 epoxy. Four different types of composites consisting of alternating layers of glass and graphite woven fabric sheets are considered. Tensile tests are conducted using 98 KN (22 kip) MTS testing machine equipped with environmental chamber. Low-velocity impact tests are conducted using an Instron-Dynatup 8250 impact test machine equipped with an environmental chamber. Ballistic impact tests are performed using helium pressured high-speed gas-gun. Tensile tests results were used to define the material behavior of the hybrid and non-hybrid composites in Finite Element modeling. The low velocity and ballistic impact tests showed that hybrid composites performance was somewhere between non-hybrid woven composites. Using woven glass fabrics as outer skin improved the impact performance of woven graphite composite. However hybrid composites are prone to delamination especially between dissimilar layers. The ballistic limit velocity V50 hybrid composites were higher that of woven graphite composite and lower than that of woven glass composite. Both destructive cross-sectional micrographs and nondestructive ultrasonic techniques are used to evaluate the damage created by impact. The Finite Element code LS-DYNA is chosen to perform numerical simulations of low velocity and ballistic impact on thick-section hybrid composites. The damage progression in these composites shows anisotropic nonlinearity. The material model to describe this behavior is not available in LS-DYNA material library. Initially, linear orthotropic material with damage (Chan-Chan Model) is employed to simulate some of the experimental results. Then, user-defined material subroutine is incorporated into LS-DYNA to simulate the nonlinear behavior. The

  12. 改性单基发射药内弹道模型%Interior Ballistic Model of Modified Single-base Propellant

    Institute of Scientific and Technical Information of China (English)

    张江波; 王琼林; 张玉成

    2012-01-01

    为研究改性单基发射药装药的内弹道特性,基于经典内弹道理论,建立了能够表征改性单基发射药燃烧特征的双气源项内弹道模型,制备了样品并进行了30mm火炮的内弹道试验验证.计算结果与试验结果相符合.通过模型计算,深入讨论了浸渍剂含量及分布、浸渍深度等因素对内弹道性能的影响.当浸渍含量分布函数为右抛物线类型时比左抛物线类型最大膛压降低了3MPa,初速提高了10m/s,实现了在较低最大膛压下更高初速的期望;浸渍深度在计算中出现临界值,当浸渍深度大于外层厚度的0.6倍时,能够得到初速增加而最大膛压不增加的内弹道效果.%In order to investigate the interior ballistic performance of Modified Single-Base Propellant(MSBP) charge,a interior ballistic model containing a item of double gas source,which is capable of expressing the burning characteristic of MSBP, was founded based on classical interior ballistics. The propellant samples were prepared,and the interior ballistic experiments of 30 mm gun were carried out to verify the model. The computational results are accordant with ex- perimental results. The deep discussion was also carried out. By the model computation, the influence of some factors on the interior ballistic performance was studied such as the content and distribution of dipping reagent, the dipping depth. Compared with a left type of parabola, the maximum chamber pressure decreases 3 MPa,and the muzzle velocity increases 10m/s when the distribution function of dipping reagent is a right type of parabola. The expectation of higher muzzle velocity under lower chamber pressure comes true. A critical value is present in the dipping depth calculation;when the dipping depth is 0.6 times greater than outer thickness,the interior ballistic effect that the maximum chamber pressure is kept invariable while the muzzle velocity is on the increase can be achieved.

  13. Possible influences on bullet trajectory deflection in ballistic gelatine.

    Science.gov (United States)

    Riva, Fabiano; Kerkhoff, Wim; Bolck, Annabel; Mattijssen, Erwin J A T

    2017-02-01

    The influence of the distance to the top and bottom of a gelatine block and to bullet tracks from previously fired shots on a bullet's trajectory, when passing through ballistic gelatine, was studied. No significant difference in deflection was found when trajectories of 9mm Luger bullets, fired at a 3.5cm distance to the top and bottom of a gelatine block and to bullet tracks from previously fired shots, were compared to trajectories of bullets fired 7cm or more away from any of the aforementioned aspects. A surprisingly consistent 6.5° absolute deflection angle was found when these bullets passed through 22.5 to 23.5cm of ballistic gelatine. The projection angle, determined by the direction of the deflection, appeared to be random. The consistent absolute angle, in combination with the random projection angle, resulted in a cone-like deflection pattern.

  14. Ballistic Missile Warhead Recognition based on Micro-Doppler Frequency

    Directory of Open Access Journals (Sweden)

    Sun Hui-Xia

    2008-11-01

    Full Text Available To elucidate the spinning-precession signatures of ballistic warhead, the model of spinning precessionfor ballistic missile warhead is established and the mathematics of micro-Doppler signatures caused by spinning-precession is derived. Then the micro-Doppler features are analysed using high-resolution time-frequencytransform, and the model predictions match the experimental data well. Based on  different mass of warheadsand decoys, the feature, which can reflect the mass of the targets, is extracted from the time-frequency plane,proving a new method for recognising warheads and discriminating these from decoys. Finally the validityof the feature extracted in this study is verified by computer simulations even with low signal-to-noise ratio.Defence Science Journal, 2008, 58(6, pp.705-709, DOI:http://dx.doi.org/10.14429/dsj.58.1697

  15. A ballistic gate-tunable contact junction in graphene

    Science.gov (United States)

    Wilmart, Quentin; Rosticher, Michael; Boukhicha, Mohamed; Inhofer, Andreas; Morfin, Pascal; Feve, Gwendal; Berroir, Jean-Marc; Placais, Bernard; Equipe de Physique Mésoscopique Team

    2015-03-01

    Field-effect control of carrier is very efficient in graphene and allows controlling the doping profile with a great accuracy and high spatial resolution. This is needed if one wants to implement Dirac fermion optics experiments or simply to improve the performance of graphene devices. In this work we realize graphene transistors equipped with a set of local back-gates that provide control of local electric fields in the 108 V / m range at the 10 nanometer scale. In particular we demonstrate ballistic contact junctions using transistors with independent channel and contact back-gates. We shall discuss the possibilities offered by this technology for ballistic electronic and opto-electronic applications.

  16. Learning without knowing: subliminal visual feedback facilitates ballistic motor learning

    DEFF Research Database (Denmark)

    Lundbye-Jensen, Jesper; Leukel, Christian; Nielsen, Jens Bo

    During daily life we are constantly bombarded by sensory input providing information on the state of our body and the surrounding world. Although we do not consciously perceive all sensory inputs, these may nevertheless have consequences for our future behavior (e.g. Goodale and Milner...... was on the screen during learning. Despite of this, there was a significantly larger learning effect in the subliminal 13-26 ms group compared to the subliminal 0 ms group. In conclusion, the results demonstrate that in addition to supraliminal feedback, subliminal feedback, which was not consciously perceived...... by the learner, indeed facilitated ballistic motor learning. This effect likely relates to multiple (conscious versus unconscious) processing of visual feedback and to the specific neural circuitries involved in optimization of ballistic motor performance....

  17. Ballistic transport in Saturn's rings - An analytic theory

    Science.gov (United States)

    Lissauer, J. J.

    1984-01-01

    Ejecta from impacts of micrometeoroids on Saturn's ring particles will, in most cases, remain in orbit about Saturn and eventually be reaccreted by the rings, possibly at a different radial location. The resulting mass transport has been suggested as the cause of some of the features observed in Saturn's rings. Previous attempts to model this transport have used numerical simulations which have not included the effects of the angular momentum transport coincident with mass transport. An analytical model for ballistic mass transport in Saturn's rings is developed. The model includes the effects of angular momentum advection and shows that the net material movement due to angular momentum advection is comparable to that caused by direct ballistic mass transport.

  18. Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

    Science.gov (United States)

    Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

    2014-01-01

    Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

  19. Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

    Directory of Open Access Journals (Sweden)

    Elias Randjbaran

    2014-01-01

    Full Text Available Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

  20. Quadrennial Defense Review and Ballistic Missile Defense Review

    Science.gov (United States)

    2010-03-11

    global defense posture 3 BMDR Highlights • Outlines a strategy and policy framework to – Defend the homeland against limited ballistic missile attack...abroad – Collaborate closely with allies and partners – Pursue a cooperative and tailored global defense posture – Strengthen US civilian capacity...reviews in 2010 – QDR and BMDR released February 1, 2010 – Nuclear Posture Review to be released this spring – Space Posture Review, with Director of

  1. Ballistic Thermal Transistor of Dielectric Four-terminal Nanostructures

    OpenAIRE

    Yang, Ping; Hu, Bambi

    2009-01-01

    We report a theoretical model for a thermal transistor in dielectric four-terminal nanostructures based on mesoscopic ballistic phonon transport, in which a steady thermal flow condition of system is obtained to set up the temperature field effect of gate. In the environment, thermal flow shows the transisting behaviors at low temperatures: saturation, asymmetry, and rectification. The phenomena can be explained reasonably by the nonlinear variation of the temperature dependence of propagatin...

  2. Pseudomagnetic fields and ballistic transport in a suspended graphene sheet.

    Science.gov (United States)

    Fogler, M M; Guinea, F; Katsnelson, M I

    2008-11-28

    We study a suspended graphene sheet subject to the electric field of a gate underneath. We compute the elastic deformation of the sheet and the corresponding effective gauge field, which modifies the electronic transport. In a clean system the two-terminal conductance of the sample is reduced below the ballistic limit and is almost totally suppressed at low carrier concentrations in samples under tension. Residual disorder restores a small finite conductivity.

  3. Model of risk assessment under ballistic statistical tests

    Science.gov (United States)

    Gabrovski, Ivan; Karakaneva, Juliana

    The material presents the application of a mathematical method for risk assessment under statistical determination of the ballistic limits of the protection equipment. The authors have implemented a mathematical model based on Pierson's criteria. The software accomplishment of the model allows to evaluate the V50 indicator and to assess the statistical hypothesis' reliability. The results supply the specialists with information about the interval valuations of the probability determined during the testing process.

  4. Ballistics Modeling for Non-Axisymmetric Hypervelocity Smart Bullets

    Science.gov (United States)

    2014-06-03

    rapidly spinning rifle bullet [2]. However, the Magnus moment can be important in terms of stability. The Magnus moment is the one effect we consider...is the result when the magnus moment is neglected. Although the magnus effect is small, the effect of neglecting it is discernable. The solution 19...11 2. Spin and Pitch Damping 11 3. Magnus Moment 12 IV. CFD Simulations and Ballistic Trajectories 12 A. CFD Modeling of a Standard Bullet 12 B

  5. Ballistic anomalies in solid rocket motors due to migration effects

    Science.gov (United States)

    Pröbster, M.; Schmucker, R. H.

    Double base and composite propellants are generally used for rocket motors, whereby double base propellants basically consist of nitrocellulose plasticized with an explosive plasticizer, mostly nitroglycerine, and in some cases with an additional inert plasticizer and ballistic additives. Composite propellants consist of an oxidizer like ammonium perchlorate and of aluminum, binder and plasticizer and often contain liquid or solid burning rate catalysts. A common feature of both propellants is that they contain smaller or larger amounts of chemically unbonded liquid species which tend to migrate. If these propellants loose part of the plasticizer by migration into the insulation layer, not only will there be a change in mechanical propellant properties but also the bond between propellant and insulation may degrade. However, depending on the severity of these effects, the change in the ballistic properties of the propellant grain caused by plasticizer migration may be of even more importance. In the past, most emphasis was placed on the behaviour of end-burning configurations. However, more recent theoretical and experimental studies revealed that not only for end-burning grain configurations but also for internal burning configurations there is a common effect which is responsible for ballistic anomalies: migration of liquid species from the propellant into the insulation. By using a plasticizer equilibrated insulation in an internal burning configuration the liquid species migration and thus the previously observed ballistic anomalies are avoided. Using this approach for end-burning configurations provides similar positive results. The various factors affecting plasticizer migration are studied and discussed, and several methods to prevent liquid species migration are described as well as methods to obtain plasticizer resistant insulations.

  6. Ballistic Evaluation of Magnesium Alloy AZ31B

    Science.gov (United States)

    2007-04-01

    S. Burkins, and William A. Gooch Weapons and Materials Research Directorate, ARL Richard D. DeLorme Magnesium Elektron North America, Inc...ballistic properties. In order to fill this gap, the U.S. Army Research Laboratory (ARL) and Magnesium Elektron North America (MENA), Inc., conducted a...plate (H24 condition). The magnesium plate was alloyed, cast, rolled, thermally treated and tensile tested by Magnesium Elektron North America (MENA

  7. System Architecture for Anti-Ship Ballistic Missile Defense (ASBMD)

    OpenAIRE

    Hobgood, Jean; Madison, Kimberly; Pawlowski, Geoffrey; Nedd, Steven.; Roberts, Michael; Rumberg, Paige

    2009-01-01

    Approved for public release; distribution is unlimited. Recent studies suggest that China is developing a new class of ballistic missiles that can be used against moving targets, such as ships. One such technology is anticipated to cover a range of 2,000 kilometers and operate at a speed of Mach 10. The threat is also capable of maneuvering both during the midcourse and terminal flight phases for the purposes of guidance, target acquisition, and countermeasures. This threat could greatl...

  8. Long-Range Ballistic Missile Defense in Europe

    Science.gov (United States)

    2010-04-26

    Standard Missile 3) missile defenses. Czech President Vaclav Klaus pronounced himself unsurprised by the announcement, and assured that he was “100...was holding the six-month revolving European Union (EU) presidency. On May 15, President Vaclav Klaus announced the installation of an interim...September 17, 2009. 5 Withdrawal From Radar No Cooling of Czech-U.S. Relations – Klaus . CTK Daily News. September 17, 2009. . Long-Range Ballistic Missile

  9. Numerical Simulation of Ballistic Impact of Layered Aluminum Nitride Ceramic

    Science.gov (United States)

    2015-09-01

    sufficient for cessation of relative motion of the projectile to that of the target. Impact velocities of 1,030; 1,100; and 1,160 m/s were considered...estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington...Distribution List 12 iv List of Figures Fig. 1 Ballistic impact problem: a) projectile and target (3 tiles) and b) finite element mesh

  10. Going ballistic:dealing with guns, gangs and knives

    OpenAIRE

    2008-01-01

    Murders involving knives and firearms never fail to grab the headlines, yet they are relatively rare. Gun crime represents only 0.4% of all recorded crime in England and Wales. The public are often sceptical, however, when they read figures such as this – and they have reason to be so. Going Ballistic's findings support four primary arguments: that official crime figures do not reflect the experiences of many communities in England and Wales; that information and intelligence sharing between ...

  11. Theory of vortices in hybridized ballistic/diffusive-band superconductors

    Science.gov (United States)

    Tanaka, K.; Eschrig, M.; Agterberg, D. F.

    2007-06-01

    We study the electronic structure in the vicinity of a vortex in a two-band superconductor in which the quasiparticle motion is ballistic in one band and diffusive in the other. This study is based on a model appropriate for such a case, that we have introduced recently [Tanaka , Phys. Rev. B 73, 220501(R) (2006)]. We argue that in the two-band superconductor MgB2 , such a case is realized. Motivated by the experimental findings on MgB2 , we assume that superconductivity in the diffusive band is “weak,” i.e., mostly induced. We examine intriguing features of the order parameter, the current density, and the vortex core spectrum in the “strong” ballistic band under the influence of hybridization with the “weak” diffusive band. Although the order parameter in the diffusive band is induced, the characteristic length scales in the two bands differ due to Coulomb interactions. The current density in the vortex core is dominated by the contribution from the ballistic band, while outside the core the contribution from the diffusive band can be substantial, or even dominating. The current density in the diffusive band has strong temperature dependence, exhibiting the Kramer-Pesch effect when hybridization is strong. A particularly interesting feature of our model is the possibility of additional bound states near the gap edge in the ballistic band, that are prominent in the vortex center spectra. This contrasts with the single band case, where there is no gap-edge bound state in the vortex center. We find the above-mentioned unique features for parameter values relevant for MgB2 .

  12. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices.

    Science.gov (United States)

    Wulf, Thomas; Schmelcher, Peter

    2016-04-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be understood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  13. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices

    CERN Document Server

    Wulf, Thomas

    2016-01-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be under- stood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  14. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices

    Science.gov (United States)

    Wulf, Thomas; Schmelcher, Peter

    2016-04-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be understood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  15. Pneumatic capillary gun for ballistic delivery of microparticles

    CERN Document Server

    Rinberg, D; Groisman, A; Rinberg, Dmitry; Simonnet, Claire; Groisman, Alex

    2005-01-01

    A pneumatic gun for ballistic delivery of microparticles to soft targets is proposed and demonstrated. The particles are accelerated by a high speed flow of Helium in a capillary tube. Vacuum suction applied to a concentric, larger diameter tube is used to completely divert the flow of Helium from the gun nozzle and prevent it from hitting the target. Depths of penetration of micron-sized gold particles into agarose gels and their speeds of ejection from the gun nozzle are measured.

  16. Analysis on Venting Time of Rarefaction Wave Gun

    Institute of Scientific and Technical Information of China (English)

    WANG Ying-ze; ZHANG Xiao-bing; YUAN Yax-iong

    2008-01-01

    Based on the operation principle of rarefaction wave gun, the selection and calculation methods for venting opportune moment are invastigated. Considering property of the rarefaction wave, taking the center of muzzle section as initial calculation point, supposing that at the moment projectile arrives to the muzzle, the rarefaction wave arrives to the base of projectile, the rarefaction wave velocity along the barrel can be obtained by fitting calculation of the interior ballis-tic data of the same closed gun and reverse deduction. And then, the optimal venting time can be found out correctly based on the rarefaction wave velocity.

  17. Pivotal role of ballistic and quasi-ballistic electrons on LED efficiency

    Science.gov (United States)

    Ni, X.; Li, X.; Lee, J.; Liu, S.; Avrutin, V.; Matulionis, A.; Özgür, Ü.; Morkoç, H.

    2010-08-01

    Significant progress in the power conversion efficiency and brightness of InGaN-based light emitting diodes (LEDs) has paved the way for these devices to be considered for LED lighting. In this realm, however, the efficiency must be retained at high injection levels in order to generate the lumens required. Unfortunately, LEDs undergo a monotonic efficiency degradation starting at current densities even lower than 50 A/cm 2 which would hinder LED insertion into the general lighting market. The physical origins for the loss of efficiency retention are at present a topic of intense debate given its enormous implications. This paper reviews the current status of the field regarding the mechanisms that have been put forward as being responsible for the loss of efficiency, such as Auger recombination, electron overflow (spillover), current crowding, asymmetric injection of electrons and holes, and poor transport of holes through the active region, the last one being applicable to multiple quantum well designs. While the Auger recombination received early attention, increasing number of researchers seem to think otherwise at the moment in that it alone (if any) cannot explain the progressively worsening loss of efficiency reduction as the InN mole fraction is increased. Increasing number of reports seems to suggest that the electron overflow is one of the major causes of efficiency degradation. The physical driving force for this is likely to be the relatively poor hole concentration and transport, and skewed injection favoring electrons owing to their relatively high concentration. Most intriguingly there is recent experimental convincing evidence to suggest that quasi-ballistic electrons in the active region, which are not able to thermalize within the residence time and possibly longitudinal optical phonon lifetime, contribute to the carrier overflow which would require an entirely new thought process in the realm of LEDs.

  18. Evaluation of bone surrogates for indirect and direct ballistic fractures.

    Science.gov (United States)

    Bir, Cynthia; Andrecovich, Chris; DeMaio, Marlene; Dougherty, Paul J

    2016-04-01

    The mechanism of injury for fractures to long bones has been studied for both direct ballistic loading as well as indirect. However, the majority of these studies have been conducted on both post-mortem human subjects (PMHS) and animal surrogates which have constraints in terms of storage, preparation and testing. The identification of a validated bone surrogate for use in forensic, medical and engineering testing would provide the ability to investigate ballistic loading without these constraints. Two specific bone surrogates, Sawbones and Synbone, were evaluated in comparison to PMHS for both direct and indirect ballistic loading. For the direct loading, the mean velocity to produce fracture was 121 ± 19 m/s for the PMHS, which was statistically different from the Sawbones (140 ± 7 m/s) and Synbone (146 ± 3 m/s). The average distance to fracture in the indirect loading was .70 cm for the PMHS. The Synbone had a statistically similar average distance to fracture (.61 cm, p=0.54) however the Sawbones average distance to fracture was statistically different (.41 cm, pballistic testing was not identified and future work is warranted.

  19. Comparing ballistic wounds with experiments on body simulator.

    Science.gov (United States)

    Bresson, F; Franck, O

    2010-05-20

    This paper demonstrates how ballistic experiments on body simulator can bring a key information in the forensic science field. In the investigated case, a hunter was shot by accident in the back. Two hunters were suspected of having inadvertently shot towards the victim. The deadly bullet left the body and cannot be found on the scene neither in the body. The only way to discriminate the two options was to perform ballistic tests in body simulators. Even though the knowledge about body simulators is not enough advanced yet to expect accurate quantitative results, it was supposed to fully discriminate the two investigated cases as its respective impact energy are highly different (respectively 1200J and 2400J). For each investigated possibility, bullet's expansion state and body wounds were simulated. Bullet impact characteristics were determined by measuring the muzzle velocity, compute the impact velocity in the considered range (the position of each hunter is accurately known). Reloading cartridges allowed to reproduce accuretaly the corresponding velocity. The body was simulated by 3 different means in order to explore the accuracy of the simulation process. We demonstrated that the reported case is situated in a velocity/energy range in which body simulators do not need to be particularly accurate to reproduce the bullet expansion/non-expansion state. It furthermore demonstrated that only one case is compatible with the ballistic wounds of the victim. In the other case, the bullet's expansion would lead to a completely different wound shape.

  20. The Second National Ballistics Imaging Comparison (NBIC-2)

    Science.gov (United States)

    Vorburger, TV; Yen, J; Song, JF; Thompson, RM; Renegar, TB; Zheng, A; Tong, M; Ols, M

    2014-01-01

    In response to the guidelines issued by the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLD/LAB-International) to establish traceability and quality assurance in U.S. crime laboratories, NIST and the ATF initiated a joint project, entitled the National Ballistics Imaging Comparison (NBIC). The NBIC project aims to establish a national traceability and quality system for ballistics identifications in crime laboratories utilizing ATF’s National Integrated Ballistics Information Network (NIBIN). The original NBIC was completed in 2010. In the second NBIC, NIST Standard Reference Material (SRM) 2461 Cartridge Cases were used as reference standards, and 14 experts from 11 U.S. crime laboratories each performed 17 image acquisitions and correlations of the SRM cartridge cases over the course of about half a year. Resulting correlation scores were collected by NIST for statistical analyses, from which control charts and control limits were developed for the proposed quality system and for promoting future assessments and accreditations for firearm evidence in U.S. forensic laboratories in accordance with the ISO 17025 Standard. PMID:26601051

  1. Quantum ballistic evolution in quantum mechanics application to quantum computers

    CERN Document Server

    Benioff, P

    1996-01-01

    Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators T is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e. motion restricted to a collection of nonintersecting or distinct paths on an arbitrary basis. The main goal of this paper is proof of a theorem which gives necessary and sufficient conditions that T must satisfy so that there exists a Hamiltonian description of quantum ballistic evolution for the process, namely, that T is a partial isometry and is orthogonality preserving and stable on some basis. Simple examples of quantum ballistic evolution for quantum Turing machines with one and with more than one type of elementary step are discussed. It is seen that for nondeterministic machines the basis set can be quite complex with much entanglement present. It is also pr...

  2. Excellent Ballistic Impact Properties Demonstrated By New Fabric

    Science.gov (United States)

    Pereira, J. Michael; Revilock, Duane M.; Hopkins, Dale A.

    2002-01-01

    Recently, a relatively new industrial fiber known by the trade name Zylon has been under commercial development by Toyobo Co., Ltd., Japan. In ballistic impact tests conducted at the NASA Glenn Research Center, it was found that dry fabric braided of Zylon had greater ballistic impact capacity than comparable (braid style and weight) fabric braided of Kevlar. To study the potential use of Zylon fabric in jet engine containment systems, the fabric was tested in Glenn's Structures and Acoustics Division Ballistic Impact Facility under conditions simulating those which occur in a jet engine blade-out event. Circular ring test specimens were fabricated by wrapping five layers of braided Zylon or Kevlar fabric around an inner ring made of a thin sheet of aluminum and a 1-in.-thick layer of aluminum honeycomb. The test specimens had an inner diameter of 40 in., an axial length of 10 in., and a wall thickness of approximately 1.5in. A test specimen is shown in the photograph.

  3. Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

    Directory of Open Access Journals (Sweden)

    Stuart Leigh Phoenix

    2017-03-01

    Full Text Available Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex, twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i a reverse-fired, fragment simulating projectile (FSP where the flat rear face impacted the yarn rather than the beveled nose; and (ii a ‘saddle-nosed projectile’ having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young’s modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre

  4. Converting Between PLY and Ballistic Research Laboratory-Computer-Aided Design (BRL-CAD) File Formats

    Science.gov (United States)

    2015-02-01

    Converting Between PLY and Ballistic Research Laboratory–Computer-Aided Design (BRL- CAD ) File Formats by Rishub Jain ARL-CR-0760...0760 February 2015 Converting Between PLY and Ballistic Research Laboratory–Computer-Aided Design (BRL- CAD ) File Formats Rishub Jain US...and Ballistic Research Laboratory–Computer-Aided Design (BRL- CAD ) File Formats 5a. CONTRACT NUMBER W911NF-10-2-0076 5b. GRANT NUMBER 5c. PROGRAM

  5. Theory of ballistic quantum transport in the presence of localized defects

    Science.gov (United States)

    Kolasiński, K.; Mreńca-Kolasińska, A.; Szafran, B.

    2016-09-01

    We present an efficient numerical approach for treating ballistic quantum transport across devices described by tight-binding (TB) Hamiltonians designated to systems with localized potential defects. The method is based on the wave function matching approach, Lippmann-Schwinger equation (LEQ), and the scattering matrix formalism. We show that the number of matrix elements of the Green's function to be evaluated for the unperturbed system can be essentially reduced by projection of the time reversed scattering wave functions on LEQ which radically improves the speed and lowers the memory consumption of the calculations. Our approach can be applied to quantum devices of an arbitrary geometry and any number of degrees of freedom or leads attached. We provide a couple of examples of possible applications of the theory, including current equilibration at the p -n junction in graphene and scanning gate microscopy mapping of electron trajectories in the magnetic focusing experiment on a graphene ribbon. Additionally, we provide a simple toy example of electron transport through 1D wire with added onsite perturbation and obtain a simple formula for conductance showing that Green's function of the device can be obtained from the conductance versus impurity strength characteristics.

  6. Development of Mortar Simulator with Shell-In-Shell System – Problem of External Ballistics

    Directory of Open Access Journals (Sweden)

    A. Fedaravicius

    2007-01-01

    Full Text Available The shell-in-shell system used in the mortar simulator raises a number of non-standard technical and computational problems starting from the requirement to distribute the propelling blast energy between the warhead and the ballistic barrel, finishing with the requirement that the length of warhead's flight path must be scaled to combat shell firing tables. The design problem of the simulator is split into two parts – the problem of external ballistics where the initial velocities of the warhead must be determined, and the problem of internal ballistics – where the design of the cartridge and the ballistic barrel must be performed.

  7. Plasma Renalase is Not Associated with Blood Pressure and Brachial-Ankle Pulse Wave Velocity in Chinese Adults With Normal Renal Function

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2016-11-01

    Full Text Available Background/Aims: This study aimed to investigate the association of renalase with blood pressure (BP and brachial-ankle pulse wave velocity (baPWV in order to better understand the role of renalase in the pathogenesis of hypertension and atherosclerosis. Methods: A total of 344 subjects with normal kidney function were recruited from our previously established cohort in Shaanxi Province, China. They were divided into the normotensive (NT and hypertensive (HT groups or high baPWV and normal baPWV on the basis of BP levels or baPWV measured with an automatic waveform analyzer. Plasma renalase was determined through an enzyme-linked immunosorbent assay. Results: Plasma renalase did not significantly differ between HT and NT groups (3.71 ± 0.69 µg/mL vs. 3.72 ± 0.73 μg/mL, P = 0.905 and between subjects with and without high baPWV (3.67 ± 0.66 µg/mL vs. 3.73 ± 0.74 µg/mL, P = 0.505. However, baPWV was significantly higher in the HT group than in the NT group (1460.4 ± 236.7 vs. 1240.7 ± 174.5 cm/s, P Conclusion: Plasma renalase may not be associated with BP and baPWV in Chinese subjects with normal renal function.

  8. Development of numerical model to investigate the laser driven shock waves from aluminum target into ambient air at atmospheric pressure and its comparison with experiment

    Science.gov (United States)

    Shiva, S. Sai; Leela, Ch.; Chaturvedi, S.; Sijoy, C. D.; Kiran, P. Prem

    2017-01-01

    A one-dimensional, three-temperature (electron, ion and thermal radiation) numerical model was developed to study the laser induced shock wave (LISW) propagation from aluminum target in ambient air at atmospheric pressure. The hydrodynamic equations of mass, momentum and energy are solved by using an implicit scheme in Lagrangian form. The model considers the laser absorption to take place via inverse-bremsstrahlung due to electron-ion (e-i) process. The flux limited electron thermal energy transport due e-i and e-n thermal energy relaxation equations are solved implicitly. The experimental characterization of spatio-temporal evolution of the LISW in air generated by focusing a second harmonic (532 nm, 7ns) of Nd:YAG laser on to surface of Al is performed using shadowgraphy technique with a temporal resolution of 1.5 ns. The velocity of SW observed in the experiments over 0.2 µs-8 µs time scales was compared with the numerical results to understand the SW transition from planar to spherical evolution.

  9. Analysis of pressure blips in aft-finocyl solid rocket motor

    Science.gov (United States)

    Di Giacinto, M.; Favini, B.; Cavallini, E.

    2016-07-01

    Ballistic anomalies have frequently occurred during the firing of several solid rocket motors (SRMs) (Inertial Upper Stage, Space Shuttle Redesigned SRM (RSRM) and Titan IV SRM Upgrade (SRMU)), producing even relevant and unexpected variations of the SRM pressure trace from its nominal profile. This paper has the purpose to provide a numerical analysis of the following possible causes of ballistic anomalies in SRMs: an inert object discharge, a slag ejection, and an unexpected increase in the propellant burning rate or in the combustion surface. The SRM configuration under investigation is an aft-finocyl SRM with a first-stage/small booster design. The numerical simulations are performed with a quasi-one-dimensional (Q1D) unsteady model of the SRM internal ballistics, properly tailored to model each possible cause of the ballistic anomalies. The results have shown that a classification based on the head-end pressure (HEP) signature, relating each other the HEP shape and the ballistic anomaly cause, can be made. For each cause of ballistic anomalies, a deepened discussion of the parameters driving the HEP signatures is provided, as well as qualitative and quantitative assessments of the resultant pressure signals.

  10. 一种基于APDL语言的船舶波浪压力自动加载方法%An Approach to Automatically Loading Wave Pressure Using APDL in ANSYS

    Institute of Scientific and Technical Information of China (English)

    丁德勇; 郑杰; 谢伟; 胡要武; 杨龙

    2011-01-01

    针对全船结构强度直接计算中,波浪加载较为麻烦的问题,提出了一种ANSYS环境下的波浪压力自动加载的方法。该方法将三维水动力程序计算的船体表面的波浪压力经过插值算法转换到有限元结构单元上,压力数据文件读入ANSYS实现了自动加载。最后,利用该自动加载方法对一艘穿浪双体船进行加载。结果表明,该方法将波浪载荷计算和结构强度分析有机结合起来了,提高了波浪压力加载的准确性和效率。%Since wave pressure loading in the direct calculation of overall ship structural strength is a time-consuming job, an automatic loading approach in the ANSYS environment was proposed. Using this method, wave pressure on ship surface calculated by 3D hydrodynamic program was transferred to Finite Element model by interpolation algorithm. The pressure data file was read into ANSYS to fulfill the automatic loading process. The automatic approach was applied to a wave piercing catamaran as an example. The results show that the proposed approach can combine the wave load calculation with ship structural strength analysis, greatly improving accuracy and efficiency of wave pressure loading.

  11. Pulse Pressure in Clinical Practice

    Directory of Open Access Journals (Sweden)

    Jiri Parenica

    2012-02-01

    Full Text Available The review presents basic information about the pulse pressure. The variables related to pulse pressure are briefly explained - arterial stiffness, arterial compliance, pulse wave velocity, pulse pressure amplification and augmentation index. We present some recent trials and observational studies that show the importance of pulse pressure in clinical practice. Briefly the possibilities of influencing the pulse pressure are discussed.

  12. Results of a Round Robin ballistic load sensing headform test series

    NARCIS (Netherlands)

    Philippens, M.A.G.; Anctil, B.; Markwardt, K.C.

    2014-01-01

    The majority of methods to assess the behind armour blunt trauma (BABT) risk for ballistic helmets is based on plastic deformable headforms. An alternative, the Ballistic Load Sensing Headform (BLSH) can record the dynamic contact force between helmet back face and the skull. Helmet BABT methods are

  13. Multiple-Sensor Discrimination of Closely-Spaced Objects on a Ballistic Trajectory

    Science.gov (United States)

    2015-05-18

    aim_point; Determine Interceptor Trajectory This segment of code calculates the trajectory necessary for the interceptor to converge on the target ...identifying and tracking an object of interest within closely-spaced objects traveling on a ballistic trajectory. The algorithms utilize a target object map...ballistic objects, dissimilar sensor correlation, target object map, Dempster-Shafer discrimination algorithms, simulation environment for various

  14. A model for evaluating the ballistic resistance of stratified packs

    Science.gov (United States)

    Pirvu, C.; Georgescu, C.; Badea, S.; Deleanu, L.

    2016-08-01

    Models for evaluating the ballistic performance of stratified packs are useful in reducing the time for laboratory tests, understanding the failure process and identifying key factors to improve the architecture of the packs. The authors present the results of simulating the bullet impact on a packs made of 24 layers, taking into consideration the friction between layers (μ = 0.4) and the friction between bullet and layers (μ = 0.3). The aim of this study is to obtain a number of layers that allows for the bullet arrest in the packs and to have several layers undamaged in order to offer a high level of safety for this kind of packs that could be included in individual armors. The model takes into account the yield and fracture limits of the two materials the bullet is made of and those for one layer, here considered as an orthotropic material, having maximum equivalent plastic strain of 0.06. All materials are considered to have bilinear isotropic hardening behavior. After documentation, the model was designed as isothermal because thermal influence of the impact is considered low for these impact velocities. The model was developed with the help of Ansys 14.5. Each layer has 200 mm × 200 × 0.35 mm. The bullet velocity just before impact was 400 m/s, a velocity characterizing the average values obtained in close range with a ballistic barrel and the bullet model is following the shape and dimensions of the 9 mm FMJ (full metal jacket). The model and the results concerning the number of broken layers were validated by experiments, as the number of broken layers for the actual pack (made of 24 layers of LFT SB1) were also seven...eight. The models for ballistic impact are useful when they are particularly formulated for resembling to the actual system projectile - target.

  15. Scaling of ballistic deposition from a Langevin equation.

    Science.gov (United States)

    Haselwandter, Christoph A; Vvedensky, Dimitri D

    2006-04-01

    An exact lattice Langevin equation is derived for the ballistic deposition model of surface growth. The continuum limit of this equation is dominated by the Kardar-Parisi-Zhang (KPZ) equation at all length and time scales. For a one-dimensional substrate the solution of the exact lattice Langevin equation yields the KPZ scaling exponents without any extrapolation. For a two-dimensional substrate the scaling exponents are different from those found from computer simulations. This discrepancy is discussed in relation to analytic approaches to the KPZ equation in higher dimensions.

  16. Ballistic Reconstruction of a Migrating Bullet in the Parapharyngeal Space

    Directory of Open Access Journals (Sweden)

    David Bächinger

    2015-01-01

    Full Text Available A 21-year-old male suffering from severe throat pain after being hit by a bullet in Syria claimed that he was shot through his eye and that the bullet subsequently descended behind his throat. Even though the first medical report stated that this course is implausible, meticulous workup provided evidence that the bullet might have entered the parapharyngeal space in a more cranial position than the one it was found eight months later. Our case highlights that bullets are able to move within the body, rendering ballistic reconstruction difficult. However, after removal of the bullet the patient’s symptoms completely resolved.

  17. Aerodynamic heating of ballistic missile including the effects of gravity

    Indian Academy of Sciences (India)

    S N Maitra

    2000-10-01

    The aerodynamic heating of a ballistic missile due to only convection is analysed taking into consideration the effects of gravity. The amount of heat transferred to the wetted area and to the nose region has been separately determined, unlike A Miele's treatise without consideration of gravity. The peak heating ratesto the wetted area and to the nose of the missile are also investigated. Finally four numerical examples are cited to estimate the errors, in heat transfers and heating ratesto both wetted area and nose region of the missile, arising out of neglecting the gravitational forces.

  18. Two-wavelength phase shift interferometry to characterize ballistic features

    Science.gov (United States)

    Pagano, Glenn W.; Mann, Christopher J.

    2014-05-01

    We apply two-wavelength phase shifting interferometry to generate 3D surface profile maps of spent bullet cartridge cases. From the captured interferograms, an optimized algorithm was used to calculate a phase profile from which a precise digital surface map of the cartridge casing may be produced. This 3D surface profile is used to enhance a firearms examiner's ability to uniquely identify distinct features or toolmarks imprinted on the casing when the weapon is fired. These features play a key role in the matching process of ballistic forensic examination.

  19. Probing magnetic microstructures with quasi-ballistic Hall crosses

    Science.gov (United States)

    Fasbender, S.; Schluck, J.; Cerchez, M.; Heinzel, T.; Sievers, S.; Pierz, K.; Schumacher, H. W.

    2016-03-01

    Hall sensing is performed on a localized magnetic field pattern using a quasi-ballistic Hall cross device. The Hall resistance shows a pronounced peak as a function of the magnetic field amplitude which is absent in the magnetization hysteresis loop. This non-monotonic response exemplifies qualitatively the failure of conventional Hall sensing. It is demonstrated how, by using a numerical simulation based on the Landauer-Büttiker model, the amplitude of the magnetic field profile can be determined from such measurements.

  20. Ballistic electron propagation through periodic few-layer graphene nanostructures

    Science.gov (United States)

    Dragoman, Daniela; Mihalache, Iulia

    2016-10-01

    We have studied electron propagation in periodic structures containing mono- and few-layer graphene regions and/or semiconducting stripes. The calculation of the transmission coefficient in all cases has been performed using transfer matrices inside regions with the same material/potential energy, as well as interface matrices between regions in which the evolution laws of charge carriers differ. Numerical simulations of the transmission coefficient, as well as of the low-temperature conductance, suggest that different periodic structures modulate differently the electrical current. The obtained results can be used to model ballistic transport in all-graphene devices, in particular in few-layer graphene structures.

  1. Persistent currents for interacting electrons in ballistic/chaotic billiards

    Science.gov (United States)

    Zelyak, Oleksandr; Murthy, Ganpathy

    2005-03-01

    We study persistent currents in a quantum billiard enclosing a magnetic flux φ by analytical and numerical methods. We concentrate on the family of Robnik-Berry billiards generated by conformal maps of the unit disk. We study the persistent current as a function of magnetic flux and parameters of the billiard in the chaotic regime. We include Fermi-liquid interactions in a mean-field approach, justified by the recent large-N approach[1] for ballistic/chaotic quantum dots. [1] G. Murthy, R. Shankar, D. Herman, and H. Mathur, Phys. Rev. B 69, 075321 (2004); G. Murthy, R. Shankar, and H. Mathur, cond-mat/0411280.

  2. Computer Aided Ballistic Orbit Classification Around Small Bodies

    Science.gov (United States)

    Villac, Benjamin F.; Anderson, Rodney L.; Pini, Alex J.

    2016-09-01

    Orbital dynamics around small bodies are as varied as the shapes and dynamical states of these bodies. While various classes of orbits have been analyzed in detail, the global overview of relevant ballistic orbits at particular bodies is not easily computed or organized. Yet, correctly categorizing these orbits will ease their future use in the overall trajectory design process. This paper overviews methods that have been used to organize orbits, focusing on periodic orbits in particular, and introduces new methods based on clustering approaches.

  3. Ballistic Applications of Glass and Kevlar Fibre Vinylester Composites

    Directory of Open Access Journals (Sweden)

    S. P. Panda

    1994-10-01

    Full Text Available Void-free E-glass and Kevlar-49 fibre reinforced vinylester laminates prepared under compression moulding were found to have Charpy impact strength of 576 KJlm2 and 304 KJlm2, respectively. Ballistic immunisation tests carried out on the glass reinforced vinylester laminates with thickness ranging from 12 mm to 54 mm against 7.62 mm rifle bullets produced an exponential relationship between the per cent attenuation in bullet velocity and the areal density of the laminates; whereas the relationship was linear for 9 mm carbine fire with laminate thicknessvarying from 5.5 mm to 12 mm .

  4. Minimum Ballistic Factor Problem of Slender Axial Symmetric Missiles

    Directory of Open Access Journals (Sweden)

    V. B. Tawakley

    1979-01-01

    Full Text Available The problem of determining the geometry of slender, axisymmetric missiles of minimum ballistic factor in hypersonic flow has been solved via the calculus of variations under the assumptions that the flow is Newtonian and the surface averaged skin-friction coefficient is constant. The study has been made for conditions of given length and diameter, given diameter and surfacearea, and given surface area and length. The earlier investigations/sup 8/ where only regular shapes were determined has been extended to cover those class of bodies which consist of regular shapes followed or preceded by zero slope shapes.

  5. Development of ballistics identification—from image comparison to topography measurement in surface metrology

    Science.gov (United States)

    Song, J.; Chu, W.; Vorburger, T. V.; Thompson, R.; Renegar, T. B.; Zheng, A.; Yen, J.; Silver, R.; Ols, M.

    2012-05-01

    Fired bullets and ejected cartridge cases have unique ballistics signatures left by the firearm. By analyzing the ballistics signatures, forensic examiners can trace these bullets and cartridge cases to the firearm used in a crime scene. Current automated ballistics identification systems are primarily based on image comparisons using optical microscopy. The correlation accuracy depends on image quality which is largely affected by lighting conditions. Because ballistics signatures are geometrical micro-topographies by nature, direct measurement and correlation of the surface topography is being investigated for ballistics identification. A Two-dimensional and Three-dimensional Topography Measurement and Correlation System was developed at the National Institute of Standards and Technology for certification of Standard Reference Material 2460/2461 bullets and cartridge cases. Based on this system, a prototype system for bullet signature measurement and correlation has been developed for bullet signature identifications, and has demonstrated superior correlation results.

  6. Wave Loads on Cylinders

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Frigaard, Peter

    1989-01-01

    Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area.......Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area....

  7. Wave-particle interaction in the Faraday waves.

    Science.gov (United States)

    Francois, N; Xia, H; Punzmann, H; Shats, M

    2015-10-01

    Wave motion in disordered Faraday waves is analysed in terms of oscillons or quasi-particles. The motion of these oscillons is measured using particle tracking tools and it is compared with the motion of fluid particles on the water surface. Both the real floating particles and the oscillons, representing the collective fluid motion, show Brownian-type dispersion exhibiting ballistic and diffusive mean squared displacement at short and long times, respectively. While the floating particles motion has been previously explained in the context of two-dimensional turbulence driven by Faraday waves, no theoretical description exists for the random walk type motion of oscillons. It is found that the r.m.s velocity ⟨μ̃(osc)⟩(rms) of oscillons is directly related to the turbulent r.m.s. velocity ⟨μ̃⟩(rms) of the fluid particles in a broad range of vertical accelerations. The measured ⟨μ̃(osc)⟩(rms) accurately explains the broadening of the frequency spectra of the surface elevation observed in disordered Faraday waves. These results suggest that 2D turbulence is the driving force behind both the randomization of the oscillons motion and the resulting broadening of the wave frequency spectra. The coupling between wave motion and hydrodynamic turbulence demonstrated here offers new perspectives for predicting complex fluid transport from the knowledge of wave field spectra and vice versa.

  8. Mission Sizing and Trade Studies for Low Ballistic Coefficient Entry Systems to Venus

    Science.gov (United States)

    Dutta, Soumyo; Smith, Brandon; Prabhu, Dinesh; Venkatapathy, Ethiraj

    2012-01-01

    The U.S and the U.S.S.R. have sent seventeen successful atmospheric entry missions to Venus. Past missions to Venus have utilized rigid aeroshell systems for entry. This rigid aeroshell paradigm sets performance limitations since the size of the entry vehicle is constrained by the fairing diameter of the launch vehicle. This has limited ballistic coefficients (beta) to well above 100 kg/m2 for the entry vehicles. In order to maximize the science payload and minimize the Thermal Protection System (TPS) mass, these missions have entered at very steep entry flight path angles (gamma). Due to Venus thick atmosphere and the steep-gamma, high- conditions, these entry vehicles have been exposed to very high heat flux, very high pressures and extreme decelerations (upwards of 100 g's). Deployable aeroshells avoid the launch vehicle fairing diameter constraint by expanding to a larger diameter after the launch. Due to the potentially larger wetted area, deployable aeroshells achieve lower ballistic coefficients (well below 100 kg/m2), and if they are flown at shallower flight path angles, the entry vehicle can access trajectories with far lower decelerations (50-60 g's), peak heat fluxes (400 W/cm2) and peak pressures. The structural and TPS mass of the shallow-gamma, low-beta deployables are lower than their steep-gamma, high-beta rigid aeroshell counterparts at larger diameters, contributing to lower areal densities and potentially higher payload mass fractions. For example, at large diameters, deployables may attain aeroshell areal densities of 10 kg/m2 as opposed to 50 kg/m2 for rigid aeroshells. However, the low-beta, shallow-gamma paradigm also raises issues, such as the possibility of skip-out during entry. The shallow-gamma could also increase the landing footprint of the vehicle. Furthermore, the deployable entry systems may be flexible, so there could be fluid-structure interaction, especially in the high altitude, low-density regimes. The need for precision in

  9. Robust Hybrid Control for Ballistic Missile Longitudinal Autopilot

    Institute of Scientific and Technical Information of China (English)

    WAEL Mohsen Ahmed; QUAN Quana

    2011-01-01

    This paper investigates the boost phase's longitudinal autopilot of a ballistic missile equipped with thrust vector control.The existing longitudinal autopilot employs time-invariant passive resistor-inductor-capacitor (RLC) network compensator as a control strategy,which does not take into account the time-varying missile dynamics.This may cause the closed-loop system instability in the presence of large disturbance and dynamics uncertainty.Therefore,the existing controller should be redesigned to achieve more stable vehicle response.In this paper,based on gain-scheduling adaptive control strategy,two different types of optimal controllers are proposed.The first controller is gain-scheduled optimal tuning-proportional-integral-derivative (PID) with actuator constraints,which supplies better response but requires a priori knowledge of the system dynamics.Moreover,the controller has oscillatory response in the presence of dynamic uncertainty.Taking this into account,gain-scheduled optimal linear quadratic (LQ) in conjunction with optimal tuning-compensator offers the greatest scope for controller improvement in the presence of dynamic uncertainty and large disturbance.The latter controller is tested through various scenarios for the validated nonlinear dynamic flight model of the real ballistic missile system with autopilot exposed to external disturbances.

  10. Four-terminal resistance of a ballistic quantum wire.

    Science.gov (United States)

    de Picciotto, R; Stormer, H L; Pfeiffer, L N; Baldwin, K W; West, K W

    2001-05-03

    The electrical resistance of a conductor is intimately related to the relaxation of the momentum of charge carriers. In a simple model, the accelerating force exerted on electrons by an applied electric field is balanced by a frictional force arising from their frequent collisions with obstacles such as impurities, grain boundaries or other deviations from a perfect crystalline order. Thus, in the absence of any scattering, the electrical resistance should vanish altogether. Here, we observe such vanishing four-terminal resistance in a single-mode ballistic quantum wire. This result contrasts the value of the standard two-probe resistance measurements of h/2e2 approximately 13 kOmega. The measurements are conducted in the highly controlled geometry afforded by epitaxial growth onto the cleaved edge of a high-quality GaAs/AlGaAs heterostructure. Two weakly invasive voltage probes are attached to the central section of a ballistic quantum wire to measure the inherent resistance of this clean one-dimensional conductor.

  11. BALLISTICS TESTING OF THE 9977 SHIPPING PACKAGE FOR STORAGE APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Loftin, B.; Abramczyk, G.; Koenig, R.

    2012-06-06

    Radioactive materials are stored in a variety of locations throughout the DOE complex. At the Savannah River Site (SRS), materials are stored within dedicated facilities. Each of those facilities has a documented safety analysis (DSA) that describes accidents that the facility and the materials within it may encounter. Facilities at the SRS are planning on utilizing the certified Model 9977 Shipping Package as a long term storage package and one of these facilities required ballistics testing. Specifically, in order to meet the facility DSA, the radioactive materials (RAM) must be contained within the storage package after impact by a .223 caliber round. In order to qualify the Model 9977 Shipping Package for storage in this location, the package had to be tested under these conditions. Over the past two years, the Model 9977 Shipping Package has been subjected to a series of ballistics tests. The purpose of the testing was to determine if the 9977 would be suitable for use as a storage package at a Savannah River Site facility. The facility requirements are that the package must not release any of its contents following the impact in its most vulnerable location by a .223 caliber round. A package, assembled to meet all of the design requirements for a certified 9977 shipping configuration and using simulated contents, was tested at the Savannah River Site in March of 2011. The testing was completed and the package was examined. The results of the testing and examination are presented in this paper.

  12. Development of a New Armor Steel and its Ballistic Performance

    Directory of Open Access Journals (Sweden)

    S. Hakan Atapek

    2013-05-01

    Full Text Available In this study, a boron added armor steel was developed according to standard rolled homogenous armor steel, MIL-A-12560, and metallographic-fractographic examinations were carried out to understand its deformation characteristics and perforation mode after interaction with a 7.62 mm armor piercing projectile. The microstructure of the developed steel was characterized by light and scanning electron microscope to evaluate its matrix after application of several heat treatments consisting of austenization, quenching and tempering. The mechanical properties of the developed steel were determined by tensile test at room temperature and notched impact test at -40 ºC. The ballistic performance of developed steel was determined by its V50 ballistic protection limit according to MIL-STD-662F standard and it was found to be higher than that of MIL-A-12560 steel. After perforation deformation induced adiabatic shear bands, that have an important role on the crack nucleation, were observed close to the penetration in the etched steel and perforation occurred by typical ductile hole enlargement with certain radial flows.Defence Science Journal, 2013, 63(3, pp.271-277, DOI:http://dx.doi.org/10.14429/dsj.63.1341

  13. Deformation and Damage of Two Aluminum Alloys from Ballistic Impact

    Science.gov (United States)

    Anderson, Charles E., Jr.; Dannemann, Kathryn A.

    2002-07-01

    A series of impact experiments were conducted on 4.76-mm-thick aluminum plates to investigate the deformation and damage behavior of two aluminum alloys, 6061-T6 and 7075-T6. The Sierra 165 lead-filled bullet was used to load the plates. Impact velocities were varied from approximately 260 m/s to 370 m/s. The flow stress for 7075-T6 aluminum is approximately twice that for 6061-T6 aluminum; however, the ballistic limit velocities differ by only 10%. The 7075-T6 aluminum plates exhibit less deformation than the 6061-T6 plates at the same impact velocity, but at some critical velocity, a through-thickness crack appears in the 7075-T6 plate, ultimately leading to plate perforation. In contrast, the 6061-T6 plates continue to deform and fail by ductile tearing. These differences in damage/failure result in the two alloys having much closer ballistic limit velocities than expected based on differences in strength.

  14. Graphene ballistic nano-rectifier with very high responsivity

    Science.gov (United States)

    Auton, Gregory; Zhang, Jiawei; Kumar, Roshan Krishna; Wang, Hanbin; Zhang, Xijian; Wang, Qingpu; Hill, Ernie; Song, Aimin

    2016-05-01

    Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ~200,000 cm2 V-1 s-1 is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW-1 with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz-1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization.

  15. Ballistic modeling of InAs nanowire transistors

    Science.gov (United States)

    Jansson, Kristofer; Lind, Erik; Wernersson, Lars-Erik

    2016-01-01

    In this work, the intrinsic performance of InAs nanowire transistors is evaluated in the ballistic limit. A self-consistent Schrödinger-Poisson solver is utilized in the cylindrical geometry, while accounting for conduction band non-parabolicity. The transistor characteristics are derived from simulations of ballistic transport within the nanowire. Using this approach, the performance is calculated for a continuous range of nanowire diameters and the transport properties are mapped. A transconductance exceeding 4S /mm is predicted at a gate overdrive of 0.5V and it is shown that the performance is improved with scaling. Furthermore, the influence from including self-consistency and non-parabolicity in the band structure simulations is quantified. It is demonstrated that the effective mass approximation underestimates the transistor performance due to the highly non-parabolic conduction band in InAs. Neglecting self-consistency severely overestimates the device performance, especially for thick nanowires. The error introduced by both of these approximations gets increasingly worse under high bias conditions.

  16. Quasi-ballistic Electronic Thermal Conduction in Metal Inverse Opals.

    Science.gov (United States)

    Barako, Michael T; Sood, Aditya; Zhang, Chi; Wang, Junjie; Kodama, Takashi; Asheghi, Mehdi; Zheng, Xiaolin; Braun, Paul V; Goodson, Kenneth E

    2016-04-13

    Porous metals are used in interfacial transport applications that leverage the combination of electrical and/or thermal conductivity and the large available surface area. As nanomaterials push toward smaller pore sizes to increase the total surface area and reduce diffusion length scales, electron conduction within the metal scaffold becomes suppressed due to increased surface scattering. Here we observe the transition from diffusive to quasi-ballistic thermal conduction using metal inverse opals (IOs), which are metal films that contain a periodic arrangement of interconnected spherical pores. As the material dimensions are reduced from ∼230 nm to ∼23 nm, the thermal conductivity of copper IOs is reduced by more than 57% due to the increase in surface scattering. In contrast, nickel IOs exhibit diffusive-like conduction and have a constant thermal conductivity over this size regime. The quasi-ballistic nature of electron transport at these length scales is modeled considering the inverse opal geometry, surface scattering, and grain boundaries. Understanding the characteristics of electron conduction at the nanoscale is essential to minimizing the total resistance of porous metals for interfacial transport applications, such as the total electrical resistance of battery electrodes and the total thermal resistance of microscale heat exchangers.

  17. Characterization of the ballistic limit curve for metallic Whipple shield

    Directory of Open Access Journals (Sweden)

    Lee M.

    2012-08-01

    Full Text Available It has been known that space debris or meteoroid impact damage can have significant effects on spacecraft. Experimental test has been conducted up to 7 km/s, and numerical simulations are performed at higher velocities. Studies on the hypervelocity impact onto single plate, double spaced plates (Whipple shield, and multiple plates (MS shield have been performed and ballistic limit curves (BLCs are proposed. Last 15 years SPH (Smoothed Particle Hydrodynamics has been applied to the hypervelocity impact problems because of cost of test and numerical efficiency especially in the hypervelocity impact regime. Although most of the simulations captured the debris shape well, somehow they do not seem to match well with the empirical ballistic limit curves. We have recently developed a new axisymmetric SPH hydrocode. In order to assess the confidence that should be placed in such simulations we simulated the hypervelocity impacts on aluminum Whipple shields and compared with the empirical BLCs. The SPH simulations indicated an improved accuracy compared with the previously published SPH simulation results. Other effort we put was using different types of equation of state, however no further improvement was achieved.

  18. Influence of Polymer Restraint on Ballistic Performanceof Alumina Ceramic Tiles

    Directory of Open Access Journals (Sweden)

    P.R.S. Reddy

    2008-03-01

    Full Text Available An experimental study has been carried out to evaluate the influence of confinement ofalumina ceramic tiles through polymer restraint, on its ballistic performance. Tiles of 99.5 per centpurity alumina were subjected to ballistic impact against 7.62 mm armour piercing projectiles atvelocities of about 820 m/s. The tiles of size 75 mm x 75 mm x 7 mm were confined on both facesby effectively bonding varying numbers of layers of polymer fabrics. These were then bondedto a 10 mm thick fibre glass laminate as a backing using epoxy resin. High performance polyethyleneand aramid polymer fabrics were used in the current set of experiments for restraining the tiles.Comparative effects of confinement on energy absorption of tiles with varied number of layersof fabrics were evaluated. It was observed that by providing effective confinement to the tile,energy absorption could be doubled with increase in areal density by about 13 per cent.Photographs of the damage and the effects of restraint on improvement in energy absorptionof ceramic tiles are presented and discussed.

  19. Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

    Directory of Open Access Journals (Sweden)

    M. F. Uddin

    2009-01-01

    Full Text Available We report improving ballistic performance of polyurethane foam by reinforcing it with nanoscale TiO2 particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt% of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nanophased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nanophased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

  20. 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.

  1. The ballistic transport instability in Saturn's rings I: formalism and linear theory

    CERN Document Server

    Latter, Henrik; Chupeau, Marie

    2012-01-01

    Planetary rings sustain a continual bombardment of hypervelocity meteoroids that erode the surfaces of ring particles on time scales of 10^5 - 10^7 years. The debris ejected from such impacts re-accretes on to the ring, though often at a slightly different orbital radius from the point of emission. This `ballistic transport' leads to a rearrangement of the disk's mass and angular momentum, and gives rise to a linear instability that generates structure on relatively large scales. It is likely that the 100-km undulations in Saturn's inner B-ring and the plateaus and 1000-km waves in Saturn's C-ring are connected to the nonlinear saturation of the instability. In this paper the physical problem is reformulated so as to apply to a local patch of disk (the shearing sheet). This new streamlined model helps facilitate our physical understanding of the instability, and also makes more tractable the analysis of its nonlinear dynamics. We concentrate on the linear theory in this paper, showing that the instability is ...

  2. 基于容积脉搏波的无创连续血压测量系统%A Non-invasive Continuous Blood Pressure Measurement System Based on Plethysmographic Pulse Wave

    Institute of Scientific and Technical Information of China (English)

    梁永波; 陈真诚; 朱健铭; 殷世民

    2013-01-01

    Objective To develop a non-invasive continuous blood pressure measurement system without the cuff based on plethysmographic pulse wave. Methods A blood pressure estimation equation was established by the stepwise regression analysis on blood pressure and pulse wave transit time which was extracted from a single circle of plethysmographic pulse wave, and then the non-invasive continuous blood pressure measurement was realized. Results Compared blood pressure value with detection by the system and Yu-Yue brand mercury sphygmomanometer from various populations, the results indicated that the two methods exhibit good coherence , and the measurement error is better than the Association for the Advancement of Medical Instrumentation (AAMI) recommendation standard. Conclusion Compared with traditional blood pressure measurement method , the non-invasive continuous blood pressure measurement method is more convenient. It can measure blood pressure continuously without cuff and invasion, and may have promising application in the future.%目的 设计一种基于容积脉搏波的无袖套连续血压测量系统.方法 从单一容积脉搏波中提取脉搏波传导时间,经逐步回归分析与血压建立血压估算方程,实现无创连续血压测量.结果 通过对不同人群血压检测,并与鱼跃牌水银血压计进行对比,结果表明该方法和传统方法具有较好的测试一致性,测量误差优于美国医疗仪器促进协会(AAMI)推荐标准.结论 该方法同传统血压测量方法相比,测量方便,可彻底摆脱缚带,并能实现无创连续测量,具有更广阔的应用前景.

  3. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources.

    Science.gov (United States)

    Shavorskiy, Andrey; Neppl, Stefan; Slaughter, Daniel S; Cryan, James P; Siefermann, Katrin R; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P; Zegkinoglou, Ioannis; Fraund, Matthew W; Khurmi, Champak; Hertlein, Marcus P; Wright, Travis W; Huse, Nils; Schoenlein, Robert W; Tyliszczak, Tolek; Coslovich, Giacomo; Robinson, Joseph; Kaindl, Robert A; Rude, Bruce S; Ölsner, Andreas; Mähl, Sven; Bluhm, Hendrik; Gessner, Oliver

    2014-09-01

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with

  4. The Independent and Joint Association of Blood Pressure, Serum Total Homocysteine, and Fasting Serum Glucose Levels With Brachial-Ankle Pulse Wave Velocity in Chinese Hypertensive Adults.

    Science.gov (United States)

    Liu, Xiaoyun; Sun, Ningling; Yu, Tao; Fan, Fangfang; Zheng, Meili; Qian, Geng; Wang, Binyan; Wang, Yu; Tang, Genfu; Li, Jianping; Qin, Xianhui; Hou, Fanfan; Xu, Xiping; Yang, Xinchun; Chen, Yundai; Wang, Xiaobin; Huo, Yong

    2016-09-28

    This study aimed to investigate the independent and joint association of blood pressure (BP), homocysteine (Hcy), and fasting blood glucose (FBG) levels with brachial-ankle pulse wave velocity (baPWV, a measure of arterial stiffness) in Chinese hypertensive adults.The analyses included 3967 participants whose BP, Hcy, FBG, and baPWV were measured along with other covariates. Systolic BP (SBP) was analyzed as 3 categories (SBP < 160 mmHg; 160 to 179 mmHg; ≥ 180 mmHg); Hcy as 3 categories (< 10 μmol/L; 10 to 14.9 μmol/L; ≥ 15.0 μmol/L) and FBG: normal (FBG < 5.6 mmol/L), impaired (5.6 mmol/L ≤ FBG < 7.0 mmol/L), and diabetes mellitus (FBG ≥ 7.0 mmol/L). We performed linear regression analyses to evaluate their associations with baPWV with adjustment for covariables.When analyzed individually, BP, Hcy, and FBG were each associated with baPWV. When BP and FBG were analyzed jointly, the highest baPWV value (mean ± SD: 2227 ± 466 cm/s) was observed in participants with FBG ≥ 7.0 mmol/L and SBP ≥ 180 mmHg (β = 432.5, P < 0.001), and the lowest baPWV value (mean ± SD: 1692 ± 289 cm/s) was seen in participants with NFG and SBP < 160 mmHg. When Hcy and FBG were analyzed jointly, the highest baPWV value (2072 ± 480 cm/s) was observed in participants with FBG ≥ 7.0 mmol/L and Hcy ≥ 15.0 μmol/L (β = 167.6, P < 0.001), while the lowest baPWV value (mean ± SD: 1773 ± 334 cm/s) was observed in participants with NFG and Hcy < 10 μmol/L.In Chinese hypertensive adults, SBP, Hcy, and FBG are individually and jointly associated with baPWV.Our findings underscore the importance of identifying individuals with multiple risk factors of baPWV including high SBP, FBG, and Hcy.

  5. High pressure generation by laser driven shock waves: application to equation of state measurement; Generation de hautes pressions par choc laser: application a la mesure d'equations d'etat

    Energy Technology Data Exchange (ETDEWEB)

    Benuzzi, A

    1997-12-15

    This work is dedicated to shock waves and their applications to the study of the equation of state of compressed matter.This document is divided into 6 chapters: 1) laser-produced plasmas and abrasion processes, 2) shock waves and the equation of state, 3) relative measuring of the equation of state, 4) comparison between direct and indirect drive to compress the target, 5) the measurement of a new parameter: the shock temperature, and 6) control and measurement of the pre-heating phase. In this work we have reached relevant results, we have shown for the first time the possibility of generating shock waves of very high quality in terms of spatial distribution, time dependence and of negligible pre-heating phase with direct laser radiation. We have shown that the shock pressure stays unchanged as time passes for targets whose thickness is over 10 {mu}m. A relative measurement of the equation of state has been performed through the simultaneous measurement of the velocity of shock waves passing through 2 different media. The great efficiency of the direct drive has allowed us to produce pressures up to 40 Mbar. An absolute measurement of the equation of state requires the measurement of 2 parameters, we have then performed the measurement of the colour temperature of an aluminium target submitted to laser shocks. A simple model has been developed to infer the shock temperature from the colour temperature. The last important result is the assessment of the temperature of the pre-heating phase that is necessary to know the media in which the shock wave propagates. The comparison of the measured values of the reflectivity of the back side of the target with the computed values given by an adequate simulation has allowed us to deduce the evolution of the temperature of the pre-heating phase. (A.C.)

  6. 超高射频串联发射内弹道一致性研究%Interior Ballistic Consistency of Serial Launch with Super-high Firing Rate

    Institute of Scientific and Technical Information of China (English)

    罗乔; 张小兵

    2012-01-01

    In order to correct the interior ballistic consistency for the serial launch with the super-high firing rate, the interior ballistic process is simulated by the code based on the classic interior ballistic model. The effects of load conditions on interior ballistic performances are analyzed under different firing rates. The modified quantitative formulas of the maximum chamber pressure and the muzzle velocity are obtained. Their consistency correction of the maximum chamber pressure and the muzzle velocity is performed by modified formulas and the simulation code. The corrected results under different firing rates show that combinely using modified formulas and the simulation code is a simple and efficient way to correct the interior ballistic consistency for the serial launch with the super-high firing rate.%为对超高射频串联发射内弹道性能进行一致性校正,该文采用经典内弹道模型编制程序,对串联发射内弹道过程进行了数值模拟.分析了不同射击频率下装填条件对内弹道性能的影响,得到了最大膛内压力和初速的定量修正公式.结合定量修正公式和数值模拟程序,对最大膛内压力和初速进行了一致性校正,得到了不同射击频率下的一致性校正结果.结果表明,联合使用定量修正公式和数值模拟程序是对超高射频串联发射内弹道性能进行一致性校正的简便而高效的方法.

  7. A new experimental setup to characterize the dynamic mechanical behaviour of ballistic yarns

    Science.gov (United States)

    Chevalier, C.; Kerisit, C.; Boussu, F.; Coutellier, D.; Faderl, N.; Klavzar, A.

    2016-10-01

    Fabrics have been widely used as part of ballistic protections since the 1970s and the development of new ballistic solutions made from fabrics need numerical simulations, in order to predict the performance of the ballistic protection. The performances and the induced mechanisms in ballistic fabrics during an impact depend on the weaving parameters and also on the inner parameters of the yarns used inside these structures. Thus, knowing the dynamic behaviour of yarn is essential to determine the ballistic behaviour of fabrics during an impact. Two major experimental devices exist and are used to test ballistic yarns in a dynamic uniaxial tension. The first one corresponds to the Split Hopkinson Tensile Bars device, which is commonly used to characterize the mechanical properties of materials in uniaxial tension and under high loading. The second one is the transversal impact device. The real conditions of ballistic impact can be realized with this device. Then, this paper deals with a new experimental setup developed in our laboratory and called the ‘tensile impact test for yarn’ (TITY) device. With this device, specific absorbed energy measurements of para-aramid yarns (336 Tex, Twaron™, 1000 filaments) have been carried out and revealed that static and dynamic properties of para-aramid are different.

  8. Ballistic Studies on TiB2-Ti Functionally Graded Armor Ceramics

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2012-11-01

    Full Text Available The objective of this paper is to discuss the results of the ballistic testing of the spark plasma sintered TiB2-Ti based functionally graded materials (FGMs with an aim to assess their performance in defeating small-calibre armor piercing projectiles. We studied the efficacy of FGM design and compared its ballistic properties with those of TiB2-based composites as well as other competing ceramic armors. The ballistic properties are critically analyzed in terms of depth of penetration, ballistic efficiency, fractographs of fractured surfaces as well as quantification of the shattered ceramic fragments. It was found that all the investigated ceramic compositions exhibit ballistic efficiency (η of 5.1 -5.9. We also found that by increasing the thickness of FGM from 5mm to 7.8 mm, the ballistic property of the composite degraded. On comparing the results with available armor systems, it has been concluded that TiB2 based composites show better ballistic properties except B4C. SEM analysis of the fragments showed that the FGM fractured by mixed mode of failure.Defence Science Journal, 2012, 62(6, pp.382-389, DOI:http://dx.doi.org/10.14429/dsj.62.2666

  9. Effect of Ballistic-Type Hot Atom Adsorption Mechanism on the Phase Diagram of Monomer-Dimer CO-O2 Surface Catalytic Reaction:A Monte Carlo Simulation

    Institute of Scientific and Technical Information of China (English)

    M. Khalid; K. M. Khan; A. U. Qaisrani; Q. N. Malik

    2004-01-01

    @@ We investigate the effect of the ballistic mechanism on the phase diagram using a square surface. While using this mechanism whenever an O2 molecule hits a randomly vacant selected site, the molecule breaks up into atomic form and then executes a ballistic flight. The paths of the two oxygen atoms are taken exactly to be opposite to each other, i.e. anti-parallel, and the ranges of the atoms are taken to be equal, i.e. they may fly up to 1 or 1.414 or 2 of the atomic spacing from the site of impact. Four cases have been studied on the basis of the range of hot atoms. The range of the hot oxygen atoms executing a ballistic flight might be up to the first nearest neighbourhood (1 atomic spacing from the site of impact), the second nearest neighbourhood (1.414 atomic spacing from the site of impact), the third nearest neighbourhood (2 atomic spacing from the site of impact),known as cases a, b, and c, respectively, while for case d the range of the oxygen atoms executing the ballistic flight might be up to 1 atomic spacing or 1.414 atomic spacing or 2 atomic spacing from the site of impact. The steady reactive window is observed and the continuous transition disappears. As soon as the CO partial pressure departs from zero, the production of CO2 is observed, which clearly verifies the experimental observation.

  10. lamb波在耐腐蚀高压容器衬里层无损检测中的应用研究%The application research of lamb waves in corrosion resistant lining layer nondestructive testing of high pressure vessel

    Institute of Scientific and Technical Information of China (English)

    吴後飞; 张艳飞

    2011-01-01

    耐腐蚀高压容器衬里层的背侧裂纹是影响设备安全性的的重要因素之一.采用常规无损检测方法对其进行检测时常存在漏检、难检等问题,对容器的安全性造成很大的威胁.通过对lamb波传播特性的分析,对自行设计制作的8mm厚的316Mod尿素级不锈钢板的人工设计制作缺陷试块进行了lamb波探伤的实验研究,研究结果表明,lamb波探伤能够实现对耐腐蚀高压容器衬里背侧裂纹的快速检测.%Dorsal crack of Corrosion resistant lining layer of high pressure vessel is one of the important factors in the safety equipment.Using conventional NDT methods often exist undetection or difficult test,and it is a great threat to the safety of vessel. It based on the analysis of the lamb wave propagation characteristics of itself,to 8mm thick 316Mod tainless steel plate artificially design flaws for the test experiments used lamb wave and verifies the lamb waves can achieve the fast test for crack detection dorsal of corrosion pressure vessel lining.

  11. Room temperature ballistic transport in InSb quantum well nanodevices.

    Science.gov (United States)

    Gilbertson, A M; Kormányos, A; Buckle, P D; Fearn, M; Ashley, T; Lambert, C J; Solin, S A; Cohen, L F

    2011-12-12

    We report the room temperature observation of significant ballistic electron transport in shallow etched four-terminal mesoscopic devices fabricated on an InSb/AlInSb quantum well (QW) heterostructure with a crucial partitioned growth-buffer scheme. Ballistic electron transport is evidenced by a negative bend resistance signature which is quite clearly observed at 295 K and at current densities in excess of 10(6) A/cm(2). This demonstrates unequivocally that by using effective growth and processing strategies, room temperature ballistic effects can be exploited in InSb/AlInSb QWs at practical device dimensions.

  12. Enhanced Rectification Efficiency In Cascaded Ballistic GaAs/AlGaAs Rectifiers

    Science.gov (United States)

    Wieser, U.; Knop, M.; Koop, P.; Kunze, U.; Reuter, D.; Wieck, A. D.

    2007-04-01

    We report on an enhanced efficiency of inertial-ballistic rectification in a cascade of rectifier stages. Each rectifier stage is composed of a pair of current injecting branches which oppositely merge into a central voltage stem. The voltages obtained at both ends of the stem enable to separate inertial-ballistic and mode-controlled rectification. In a cascade composed of two rectifier stages the total inertial-ballistic signal is enhanced compared to the single contributions while the mode-controlled signal is almost unaffected.

  13. A discussion on the usefulness of a shared European ballistic image database.

    Science.gov (United States)

    De Ceuster, J; Hermsen, R; Mastaglio, M; Nennstiel, R

    2012-12-01

    The introduction of electronic systems into the comparison of weapon marks in the mid 1990s caused a revolution in the discipline of "forensic ballistics". Most European states now use this technology to search their national open case files. Globalisation of crime and the loss of effective border controls have made the idea of a unified European ballistic system seem logical. The article critically considers the requirements and possible outcomes of such a system. Based on the experience of forensic practitioners it seems probable that a shared European electronic ballistic system will be of a very limited value at present. Further improvements of existing systems to reach compatibility are encouraged.

  14. Performance Comparison of EKF/UKF/CKF for the Tracking of Ballistic Target

    Directory of Open Access Journals (Sweden)

    Wu Guang-bin

    2012-11-01

    Full Text Available This paper considers three well know nonlinear Kalman Filters for the tracking of a ballistic target. Extended Kalman Filter (EKF, Unscented Kalman Filter (UKF, and the Cubature Kalman Filter (CKF are applied for estimating the position, velocity and the ballistic coefficient of the ballistic target. The theory formulation and computer simulation has been done for the comparison of the three nonlinear Kalman Filters. Results show that all of them can accomplish the estimation task, but the UKF and CKF both have higher accuracy and less computation cost than the EKF.

  15. Closed vessel technique for assessment of ballistic characteristics in quality control of propellant manufacture

    Directory of Open Access Journals (Sweden)

    G. Siva Ramakrishnan

    1958-07-01

    Full Text Available "In order to assess the ballistic performance of a propellant it is necessary to measure its following characteristics: (aForce constant, (bvivacity, and (cshape. It is possible to determine (aand (bby the closed vessel technique which enables ballistic performance of the propellant in the gun to be estimated. It can be very usefully employed for quality control of propellant manufacture. As more and more experience is gained in the closed vessel technique these tests have several other possible practical applications such as those: (afor inspection of propellants, (bfor assessment of quality, (c to reduce proof in guns, and (dto check ballistics of a lot after long storage."

  16. Application of Extended Kalman Filter to Tactical Ballistic Missile Re-entry Problem

    CERN Document Server

    Bhowmik, Subrata

    2007-01-01

    The objective is to investigate the advantages and performance of Extended Kalman Filter for the estimation of non-linear system where linearization takes place about a trajectory that was continually updated with the state estimates resulting from the measurement. Here tactile ballistic missile Re-entry problem is taken as a nonlinear system model and Extended Kalman Filter technique is used to estimate the positions and velocities at the X and Y direction at different values of ballistic coefficients. The result shows that the method gives better estimation with the increase of ballistic coefficient.

  17. Influence of Material Properties on the Ballistic Performance of Ceramics for Personal Body Armour

    Directory of Open Access Journals (Sweden)

    Christian Kaufmann

    2003-01-01

    Full Text Available In support of improved personal armour development, depth of penetration tests have been conducted on four different ceramic materials including alumina, modified alumina, silicon carbide and boron carbide. These experiments consisted of impacting ceramic tiles bonded to aluminum cylinders with 0.50 caliber armour piercing projectiles. The results are presented in terms of ballistic efficiency, and the validity of using ballistic efficiency as a measure of ceramic performance was examined. In addition, the correlation between ballistic performance and ceramic material properties, such as elastic modulus, hardness, spall strength and Hugoniot Elastic Limit, has been considered.

  18. Ballistic Resistance of Armored Passenger Vehicles: Test Protocols and Quality Methods

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey M. Lacy; Robert E. Polk

    2005-07-01

    This guide establishes a test methodology for determining the overall ballistic resistance of the passenger compartment of assembled nontactical armored passenger vehicles (APVs). Because ballistic testing of every piece of every component of an armored vehicle is impractical, if not impossible, this guide describes a testing scheme based on statistical sampling of exposed component surface areas. Results from the test of the sampled points are combined to form a test score that reflects the probability of ballistic penetration into the passenger compartment of the vehicle.

  19. General-Service Ballistic Computer Programming Based on B-Method

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yu-jun; ZHANG Zi-qiu; WANG Jin-quan; XUE Jin-yun

    2006-01-01

    Formal methods offer the promise of significant improvement on quality and reliability of critical embedded software. B-Method is employed to develop general-service ballistic computer programs in the paper, each of which can be adapted to a family of service/weapon-specific ballistic computers. Based on the structuring mechanisms of B-method, a unified approach is proposed to systematically control the complexity of ballistic parameters in the process of type and operation refinement, and ultimately a series of high reliable, reusable, and scalable programs are produced. Experiences with the application of the method and tools are also discussed.

  20. Comparison of magnetoresistances of triangular and rectangular ballistic graphene npn junctions

    Science.gov (United States)

    Morikawa, Sei; Masubuchi, Satroru; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki

    2016-10-01

    We compared the magnetotransport properties of ballistic graphene npn junctions with two different geometries. We found that a rectangular npn junction shows a positive magnetoresistance around zero magnetic field; this finding can be explained by the suppression of Klein tunneling in a finite magnetic field. In contrast, a triangular npn junction shows a negative magnetoresistance because the transmission is enhanced in a commensurability magnetic field where the ballistic carriers in a cyclotron motion are injected perpendicularly to both the np and pn interfaces. These results suggest possibilities for manipulating ballistic carrier trajectories through the designs of local-gate geometries.

  1. Ultrasonic Lamb Wave Testing of Hydrogen Bubble in Pressure Vessel Plate%压力容器板材中氢鼓泡缺陷的超声Lamb波检测

    Institute of Scientific and Technical Information of China (English)

    杨齐; 陈定岳; 陈虎; 王杜

    2016-01-01

    采用 WAVE 2000数值计算软件对一16 mm 厚人工模拟试板的内壁鼓包缺陷进行超声Lamb 波仿真模拟,模拟结果表明,采用Lamb 波从外壁对压力容器板材内壁氢鼓泡检测是可行的;同时,给出了最优检测参数,为实际检测提供了 Lamb 波模式、频率、入射角度等参数的选择参考。根据仿真结果,采用最优检测参数对人工模拟试板进行 Lamb 波的实际检测试验,结果表明:该方法检测效果良好,不仅能够检出缺陷,而且缺陷定位精度也较高。%WAVE 2000 numerical software was used for ultrasonic Lamb wave simulation of the inner wall bubble defect of a 1 6 mm thick artificial test plate.The results showed that it was feasible to detect the hydrogen bubbles in the inner wall of pressure vessel plate by using Lamb wave from the outer wall,and the optimal detection parameters were given,the reference of important parameters such as Lamb wave mode,frequency,incidence angle for actual testing was provided.According to the simulation results,the optimal detection parameters were used for Lamb wave testing,which was not only able to detect defect,but also had high localization accuracy.

  2. 可压缩流体饱和孔隙介质中孔隙压力波传播数值分析%Numerical analysis of propagation of pore pressure waves in compressible fluid saturated porous media

    Institute of Scientific and Technical Information of China (English)

    杨多兴; 李琦; 王舒

    2014-01-01

    首次将高精度时空守恒元/解元方法推广到可压缩流体饱和孔隙介质中孔隙压力波传播的数值计算中。将孔隙度梯度从源(汇)项中分离,直接引入流通量,改进了理论模型。通过对孔隙介质激波问题的数值模拟,验证了方法的精度和有效性。在此基础上,提出了孔隙介质中二维黎曼问题,并揭示了孔隙压力波存在接触间断、激波、膨胀波、压缩波等复杂的结构特征。该成果对二氧化碳地质封存、二氧化碳提高石油采收率、页岩气压裂开采以及地震破裂过程的研究具有重要的理论与应用意义。%The governing equations of the propagation of shock waves in compressible fluid saturated deformable porous media are improved by the way the porosity gradient terms are treated in the flow flux vector. An updated space-time conservation element and solution element (CE/SE) method, which is a new approach in computational fluid dynamics (CFD), is presented to depict global and local flux conservation in space-time domain. The physical model and the CE/SE method are both validated with the experimental study based on the head-on collision of a planar shock wave through a rigid porous material;and then good agreements are found to be evident. After that, the two-dimensional Riemann problem in the porous media is established. It is found that the wave structures of the pore pressure consist of shock waves, compaction waves, expansion waves and the contact discontinuity. To our best knowledge, this is the first time that pore pressure waves have been successfully simulated with the CE/SE method inside a multiphase deformable porous medium. The findings are potentially applicable to CO2 geological storage, CO2 enhanced oil recovery, shale gas exploration and earthquake rupture processes.

  3. A ballistic-pendulum test stand to characterize small cold-gas thruster nozzles

    Science.gov (United States)

    Lugini, Claudio; Romano, Marcello

    2009-03-01

    This paper deals with the design, development and experimentation of a new test stand for the accurate and precise characterization of small cold-gas nozzles having thrust of the order of 0.1 N and specific impulse of the order of 10 s. As part of the presented research, a new cold-gas supersonic nozzle was designed and developed based on the quasi one-dimensional theory. The test stand is based on the ballistic-pendulum principle: in particular, it consists of a suspended gondola hosting the propulsion system and the sample nozzle. The propulsion system consists of an air tank, pressure regulator, solenoid valve, battery and digital timer to command the valve. The gondola is equipped with a fin, immersed in water, to provide torsional and lateral oscillation damping. A laser sensor measures the displacement of the gondola. The developed test stand was calibrated by using a mathematical model based on the inelastic collision theory. The obtained accuracy was of ˜1%. Sample experimental results are reported regarding the comparison of the new supersonic nozzle with a commercially available subsonic nozzle. The obtained measurements of thrust, mass flow rate and specific impulse are precise to a level of ˜3%. The broad goal of the presented research was to contribute to an upgraded design of a spacecraft simulator used for laboratory validation of guidance, navigation and control algorithms for autonomous docking manoeuvres.

  4. Internal Ballistic Code for Solid Rocket Motors using Minimum Distance Function for Grain Burnback

    Directory of Open Access Journals (Sweden)

    Afroz Javed

    2015-05-01

    Full Text Available A computer code has been developed for internal ballistic performance evaluation of solid rocket motors, using minimum distance function (MDF approach for prediction of geometry evolution. This method can handle any complex geometry without the need to define different geometrical shapes and their evolution as used in several existing analytical geometry evolution-based methodologies. The code is validated with both experimental results published in literature, as well as for solid rocket motors of tactical and strategic missiles and a very good match is obtained with static test results. The output of the code gives p-t (pressure-time curve as well as the detailed parameters of the flow along the axial direction, and geometries in the form of mesh file, which can be further used as input to codes for CFD analysis.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.181-188, DOI: http://dx.doi.org/10.14429/dsj.65.8304

  5. Numerical Modelling of Caseless Ammunition with Coreless Bullet in Internal Ballistics

    Directory of Open Access Journals (Sweden)

    U. S. Silva-Rivera

    2015-05-01

    Full Text Available In the search of a new weapon for combat in short range, it is proposed the use of a new experimentally designed 7.62 mm calibre ammunition with a lighter weight (caseless-coreless. This can be used in carbine assault rifles with short barrel or pistols. In this work, the compressible gases flowing through the gun barrel caused by the proposed ammunition were experimentally and numerically analysed. The Large Eddy Simulation was used for the numerical simulation, considering a compressible and turbulent flow, with the chemical species transport model and a complete conversion of the propellant reaction. Variations in pressure and temperature were compared with the results obtained from a conventional 7.62 mm full metal jacket (FMJ ammunition. Results of ballistic experimental tests and numerical simulations were similar than those of the 9 mm x 19 mm FMJ ammunitions, showing feasibility for the development of new weapons intended for operations of short range shots.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.203-207, DOI: http://dx.doi.org/10.14429/dsj.65.8511

  6. Constitutive equations of a ballistic steel alloy as a function of temperature

    Directory of Open Access Journals (Sweden)

    Coghe F.

    2012-08-01

    Full Text Available In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB. The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.

  7. Fascial hierarchies and the relevance of crossed-helical arrangements of collagen to changes in shape; part II: The proposed effect of blood pressure (Traube-Hering-Mayer) waves on the fascia.

    Science.gov (United States)

    Scarr, Graham

    2016-07-01

    Periodic changes in arterial pressure and volume have long been related to respiratory and sympathetic nerve activity (Traube-Hering-Mayer waves) but their origins and nomenclature have caused considerable confusion since they were first discovered in the eighteenth century. However, although they remain poorly understood and the underlying details of their control are complicated, these waves do provide valuable clinical information on the state of blood pressure regulation in both normal and pathological conditions; and a correlation with oscillatory motions observed by certain practitioners suggests that they may also have some physiological value that relates to changes in the volume of fascial 'tubes'. Part I of this paper (Scarr, 2016) described a complex fascial network of collagen-reinforced tubular sheaths that are an integral part of muscle structure and function, and continuous with 'higher-level' fascial tubes surrounding groups of muscles, the limbs and entire body. The anisotropic arrangements of collagen fibres within the walls of these tubes reflect the most efficient distribution of mechanical stresses and have been considered to coordinate changes in shape, and a proposed link between cyclic variations in arterial pressure and volume, and the behaviour of these fascial compartments is now described.

  8. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Friis-Madsen, Erik

    2006-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57!27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world’s first offshore wave energy...

  9. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter Bak; Friis-Madsen, Erik

    2004-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57 x 27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world's first offshore wave energy...

  10. Parametric Studies on Star Port Propellant Grain For Ballistic Evaluation

    Directory of Open Access Journals (Sweden)

    Himanshu Shekhar

    2005-10-01

    Full Text Available Star port propellant grains have been extensively studied for their operating as well as geometrical parameters. It is observed that reduced tail-off and better neutrality cannot be achieved simultaneously in a configuration. Parametric study is conducted to know the effect of various parameters of star-shaped propellant grains for ballistic evaluation motor. For reduced tail-off, higher characteristic velocity, lower outer diameter of the star, and lower value of angular fraction is preferred. Star angle, burning rate, and throat diameter have negligible effects on the tail-off factor. For better neutrality, higher value of angular  fraction, higher star outer diameter, and star angle near to neutrality, is needed. An alternate configuration is suggested using this parametric study to ascertain least tail-off and enhanced neutrality.

  11. Electron optics with p-n junctions in ballistic graphene

    Science.gov (United States)

    Chen, Shaowen; Han, Zheng; Elahi, Mirza M.; Habib, K. M. Masum; Wang, Lei; Wen, Bo; Gao, Yuanda; Taniguchi, Takashi; Watanabe, Kenji; Hone, James; Ghosh, Avik W.; Dean, Cory R.

    2016-09-01

    Electrons transmitted across a ballistic semiconductor junction are expected to undergo refraction, analogous to light rays across an optical boundary. In graphene, the linear dispersion and zero-gap band structure admit highly transparent p-n junctions by simple electrostatic gating. Here, we employ transverse magnetic focusing to probe the propagation of carriers across an electrostatically defined graphene junction. We find agreement with the predicted Snell’s law for electrons, including the observation of both positive and negative refraction. Resonant transmission across the p-n junction provides a direct measurement of the angle-dependent transmission coefficient. Comparing experimental data with simulations reveals the crucial role played by the effective junction width, providing guidance for future device design. Our results pave the way for realizing electron optics based on graphene p-n junctions.

  12. A Predictive Explicit Guidance Scheme for Ballistic Missiles

    Directory of Open Access Journals (Sweden)

    N. Prabhakar

    2013-09-01

    Full Text Available A new approach to the design of ballistic missile guidance is presented in this paper. The proposed method uses the missile model to predict the likely impact point at every guidance cycle and apply course corrections based on the predicted impact point (PIP deviations. The algorithm also estimates the in-flight thrust variation from nominal and accordingly updates the model to reduce the uncertainty in the prediction of the impact point. The performance of the algorithm is tested through 6-DOF simulation. The simulation results show excellent performance of the proposed guidance scheme in nominal & off nominal cases.Defence Science Journal, 2013, 63(5, pp.456-461, DOI:http://dx.doi.org/10.14429/dsj.63.2575

  13. Steepest descent ballistic deposition of complex shaped particles

    Science.gov (United States)

    Topic, Nikola; Pöschel, Thorsten

    2016-03-01

    We present an efficient event-driven algorithm for sequential ballistic deposition of complex-shaped rigid particles. Each of the particles is constructed from hard spheres (typically 5 … 1000) of variable radii. The sizes and relative positions of the spheres may mutually overlap and can be chosen such that the surface of the resulting particle appears relatively smooth. In the sequential deposition process, by performing steps of rolling and linear motion, the particles move along the steepest descent in a landscape formed by the boundaries and previously deposited particles. The computer time for the simulation of a deposition process depends on the total number of spheres but only weakly on the sizes and shapes of the particles. The proposed algorithm generalizes the Visscher-Bolsterli algorithm [1] which is frequently used for packing of spheres, to non-spherical particles. The proposed event-driven algorithm allows simulations of multi-million particle systems using desktop computers.

  14. Study of surface charges in ballistic deflection transistors

    Science.gov (United States)

    Millithaler, J.-F.; Iñiguez-de-la-Torre, I.; Mateos, J.; GonzáIez, T.; Margala, M.

    2015-12-01

    This paper presents a comprehensive study of the behavior of surface charges in ballistic deflection transistors, at room temperature, where the in-plane geometry associating two drains with two gates in push-pull modes allows the control of electron path. Monte Carlo simulations were performed and compared with experimental data by using different models for accounting for surface charge effects. The simple model which assumes a constant and uniform value of the surface charge provides good results at equilibrium, but it is not able to correctly reproduce the BDT’s complex behavior when biased. We have confirmed that for a correct description of the device operation it is necessary to use a model allowing the surface charge to adapt itself locally to the carrier concentration in its surroundings.

  15. Ballistic Impact on Glass/Epoxy Composite Laminates

    Directory of Open Access Journals (Sweden)

    R. Velmurugan

    2014-07-01

    Full Text Available Glass/epoxy composite laminates are subjected to impact loading and the energy absorbing capacity of the laminates is studied. In the present study, laminates with four different orientations and thickness values are considered. Analytical study is carried out based on energy method and results are compared with FE results obtained from Abaqus/Explicit software. Results obtained from the analytical methods are showing good agreement with the FE results. It is found that cross-ply laminates are most efficient in ballistic resistance when compared with the laminates of other orientations. It is also noticed that the energy absorbing capacity is decreasing with increase in velocity of the projectile for a given lay-up and thickness value.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 393-399, DOI:http://dx.doi.org/10.14429/dsj.64.3882 

  16. Semiclassical Quantization of Spinning Quasiparticles in Ballistic Josephson Junctions

    Science.gov (United States)

    Konschelle, François; Bergeret, F. Sebastián; Tokatly, Ilya V.

    2016-06-01

    A Josephson junction made of a generic magnetic material sandwiched between two conventional superconductors is studied in the ballistic semiclassic limit. The spectrum of Andreev bound states is obtained from the single valuedness of a particle-hole spinor over closed orbits generated by electron-hole reflections at the interfaces between superconducting and normal materials. The semiclassical quantization condition is shown to depend only on the angle mismatch between initial and final spin directions along such closed trajectories. For the demonstration, an Andreev-Wilson loop in the composite position-particle-hole-spin space is constructed and shown to depend on only two parameters, namely, a magnetic phase shift and a local precession axis for the spin. The details of the Andreev-Wilson loop can be extracted via measuring the spin-resolved density of states. A Josephson junction can thus be viewed as an analog computer of closed-path-ordered exponentials.

  17. Design and Ballistic Performance of Hybrid Composite Laminates

    Science.gov (United States)

    Ćwik, Tomasz K.; Iannucci, Lorenzo; Curtis, Paul; Pope, Dan

    2016-10-01

    This paper presents an initial design assessment of a series of novel, cost-effective, and hybrid composite materials for applications involving high velocity impacts. The proposed hybrid panels were designed in order to investigate various physical phenomenon occurring during high velocity impact on compliant laminates from a previous study on Dyneema® and Spectra®. In the first, screening phase of the study twenty different hybrid composite laminates were impacted with 20 mm Fragment Simulating Projectiles at 1 km/s striking velocity. The best performing concepts were put forward to phase II with other hybrid concepts involving shear thickening fluids, commonly used in low velocity impacts. The results indicated that it is possible to design hybrid laminates of similar ballistic performance as the reference Dyneema® laminate, but with lower material costs. The optimal hybrid concept involves a fibre reinforced Polypropylene front and a Dyneema® backing.

  18. Interacting electrons in ballistic conformal billiard quantum dots

    Science.gov (United States)

    Murthy, Ganpathy; Mathur, Harsh; Shankar, Ramamurti

    2004-03-01

    Interacting electrons in a ballistic quantum dot present a novel regime of disorder + interactions. An instability of the ground state towards a spontaneous deformation of the Fermi surface (the Pomeranchuk transition) has been found by the present authors[1], by assuming that Random Matrix Theory describes the states in the Thouless shell near the Fermi energy. However, the question of whether the mesoscopic transition occurs before the bulk transition remains open[2]. Here we describe calculations on the conformal billiard[3] and attempt to see how well RMT assumptions hold, and to what extent the physics of the transition is described by our previous work. 1. G. Murthy, R. Shankar, D. Herman, and H. Mathur, cond-mat/0306529. 2. S. Adam, P. W. Brouwer, and P. Sharma, cond-mat/0309074. 3. M. V. Berry and M. Robnik, J. Phys. A19, 669 (1986).

  19. Ballistic gelatin as a putative substrate for EEG phantom devices

    CERN Document Server

    Hairston, W David; Yu, Alfred B

    2016-01-01

    Phantom devices allow the human variable to be controlled for in order to allow clear comparison and validation of biomedical imaging hardware and software. There is currently no standard phantom for electroencephalography (EEG). To be useful, such a device would need to: (a) accurately recreate the real and imaginary components of scalp electrical impedance, (b) contain internal emitters to create electrical dipoles, and (c) be easily replicable across various labs and research groups. Cost-effective materials, which are conductive, repeatable, and easily formed are a missing key enabler for EEG phantoms. Here, we explore the use of ballistics gelatin, an inexpensive, easily-formable and repeatable material, as a putative substrate by examining its electrical properties and physical stability over time. We show that varied concentrations of NaCl salt relative to gelatin powder shifts the phase/frequency response profile, allowing for selective tuning of the material electrical properties.

  20. Prediction of the ballistic limit of an aluminium sandwich panel

    Science.gov (United States)

    Campbell, J.; De Vuyst, T.; Vignjevic, R.; Hughes, K.

    2016-08-01

    This paper presents research on modelling the impact of a 150g projectile on a 35mm thick aluminium sandwich panel. The objective of the work is a predictive modelling capability for the ballistic limit of the panel. A predictive modelling capability supports the design of capture and deorbit missions for large items of space debris such as satellites and rocket upper stages. A detailed explicit finite element model was built using the LSDYNA software and results were compared with experimental data for the projectile exit velocity to establish key parameters. The primary parameters influencing the model behaviour were the strength and failure of the aluminium face sheets and the friction between projectile and panel. The model results showed good agreement with experimental results for ogive nose projectiles, but overestimated the exit velocity for flat nose projectiles.