The Ballistic Pressure Wave Theory of Handgun Bullet Incapacitation
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.
Ballistic pressure wave contributions to rapid incapacitation in the Strasbourg goat tests
Courtney, M; Courtney, Amy; Courtney, Michael
2007-01-01
This article presents empirical models for the relationship between peak ballistic pressure wave magnitude and incapacitation times in the Strasbourg goat test data. Using a model with the expected limiting behavior at large and small pressure wave magnitudes, the average incapacitation times are highly correlated (R = 0.91) with peak pressure wave magnitude. The cumulative incapacitation probability as a function of time reveals both fast (t 5 s) incapacitation mechanisms. The fast incapacitation mechanism can be accurately modeled as a function of peak pressure wave magnitude. The slow incapacitation mechanism is presumably due to blood loss via damaged vascular tissue.
Courtney, Amy; Courtney, Michael
2008-01-01
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 pig...
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...
Phonon wave propagation in ballistic-diffusive regime
Tang, Dao-Sheng; Hua, Yu-Chao; Nie, Ben-Dian; Cao, Bing-Yang
2016-03-01
Wide applications of ultra-short pulse laser technique in micromachining and thermophysical properties' measurements make the study on ultrafast transient thermal transport necessarily essential. When the characteristic time is comparable to the phonon relaxation time, phonons propagate in ballistic-diffusive regime and thermal wave occurs. Here, ultrafast transient phonon transport is systematically investigated based on the Monte Carlo (MC) simulations, the Cattaneo-Vernotte (C-V) model, and the phonon Boltzmann transport equation (BTE). It is found that remarkable differences exist between the C-V model and the MC simulations when describing the evolution of the thermal wave excited by the ultra-short heat pulse. The C-V model predicts a non-dispersive dissipative thermal wave, while the MC simulation with Lambert emission predicts a dispersive dissipative thermal wave. Besides, different phonon emissions can significantly influence the evolution of the thermal wave in the MC simulations. A modified C-V model with a time- and position-dependent effective thermal conductivity is derived based on the phonon BTE to characterize the evolution of the transport regime from ballistic to diffusive. The integrations on moments of the distribution function cause the loss of the information of the phonon distribution in wave vector space, making the macroscopic quantities incomplete when describing the ballistic transport processes and corresponding boundary conditions. Possible boundary conditions for the phonon BTE in practice are also discussed on different heating methods.
A Thoracic Mechanism of Mild Traumatic Brain Injury Due to Blast Pressure Waves
Courtney, Amy; Courtney, Michael
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 b...
Comparison of third-order plasma wave echoes with ballistic second-order plasma wave echoes
The apparent dispersion of third-order plasma wave echoes observed in a high frequency plasma is compared with that of simultaneously observed ballistic second-order echoes. Amplitude and wavelength of third-order echoes are found to be always smaller than those of second-order echoes, however, the dispersion curves of both types of echoes are very similar. These observations are in qualitative agreement with calculations of special ballistic third-order echoes. The ballistic nature of the observed third-order echoes may, therefore, be concluded from these measurements. (author)
Ballistic quench-induced correlation waves in ultracold gases
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...
A Thoracic Mechanism of Mild Traumatic Brain Injury Due to Blast Pressure Waves
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. ...
Comments on "Ballistics: a primer for the surgeon"
Courtney, Michael; Courtney, Amy
2008-01-01
In response to a published assertion to the contrary, this paper briefly reviews many studies that document remote wounding effects of ballistic pressure waves including experiments in pigs and dogs that find brain injury resulting from animal models shot in the thigh and case studies in humans that document both remote brain and spinal cord injuries ascribed to ballistic pressure waves.
On Ballistics Solution of HL Pressure Gun for Composite Charges Taking Most General Form Function
Padam Chand Gupta
1977-01-01
Full Text Available The present paper gives the solution of the equation of internal ballistics of H/L gun for composite charges taking most general form function assuming constant pressure in both the chambers during the second stage of burning, i.e., after the burning of the first component charge.
Observation of strong reflection of electron waves exiting a ballistic channel at low energy
Vaz, Canute I.; Liu, Changze; Campbell, Jason P.; Ryan, Jason T.; Southwick, Richard G., III; Gundlach, David; Oates, Anthony S.; Huang, Ru; Cheung, Kin. P.
2016-06-01
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.
Ballistic orbits in Schwarzschild space-time and gravitational waves from EMR binary mergers
We describe a special class of ballistic geodesics in Schwarzschild space-time, extending to the horizon in the infinite past and future of observer time, which are characterized by the property that they are in 1–1 correspondence, and completely degenerate in energy and angular momentum, with stable circular orbits. We derive analytic expressions for the source terms in the Regge–Wheeler and Zerilli–Moncrief equations for a point-particle moving on such a ballistic orbit, and compute the gravitational waves emitted during the infall in an extreme mass ratio black-hole binary coalescence. In this way a geodesic approximation to the plunge phase of compact binaries is obtained. (paper)
Calculations are presented for the scattering and ballistic transport of spin waves (SW) incident from cobalt leads, on ultrathin ferrimagnetic cobalt–gadolinium ‥Co][Co(1−c)Gd(c)]ℓ[Co‥ nanojunction systems. The nanojunction [Co(1−c)Gd(c)]ℓ itself is a randomly disordered alloy of thickness ℓ hcp lattice planes between matching hcp planes of the Co leads, at known stable concentrations c≤0.5 for this alloy system. To compute the spin dynamics, and the SW scattering and ballistic transport, this alloy nanojunction is modeled in the virtual crystal approximation (VCA), valid in particular at the length scale of the nanojunction for submicroscopic SW wavelengths. The phase field matching theory (PFMT) is applied to compute the localized and resonant magnons on the nanojunction. These magnons, characteristic of the embedded nanostructure, propagate in its symmetry plane with spin precession amplitudes that decay or match the spin wave states in the semi-infinite leads. The eigenvectors of these magnon modes are calculated for certain cases to illustrate the spin precession configurations on the nanojunction. The VCA-PFMT approach is also used to calculate the reflection and transmission spectra for the spin waves incident from the Co leads on the nanojunction. The results demonstrate resonance assisted maxima for the ballistic SW transmission spectra due to interactions between the incident spin waves and the nanojunction magnon modes. These properties are general for variable nanojunction thicknesses and alloy stable concentrations c≤0.5. In particular, the positions of the resonance assisted maxima of spin wave transmission can be modified with nanojunction thickness and alloy concentration. - Highlights: • Model is presented for spin wave scattering at CoGd disordered alloy nanojunctions. • Computations yield the localized and resonant magnon modes on the nanojunctions. • The spin waves ballistic reflection and transmission spectra are
The ballistic transport instability in Saturn's rings II: nonlinear wave dynamics
Latter, Henrik; Chupeau, Marie
2014-01-01
The ejecta discharged by impacting meteorites can redistribute a planetary ring's mass and angular momentum. This `ballistic transport' of ring properties instigates a linear instability that could generate the 100--1000-km undulations observed in Saturn's inner B-ring and in its C-ring. We present semi-analytic results demonstrating how the instability sustains steadily travelling nonlinear wavetrains. At low optical depths, the instability produces approximately sinusoidal waves of low amplitude, which we identify with those observed between radii 77,000 and 86,000 km in the C-ring. On the other hand, optical depths of 1 or more exhibit hysteresis, whereby the ring falls into multiple stable states: the homogeneous background equilibrium or large-amplitude wave states. Possibly the `flat zones' and `wave zones' between radii 93,000 and 98,000 km in the B-ring correspond to the stable homogeneous and wave states, respectively. In addition, we test the linear stability of the wavetrains and show that only a s...
The ballistic electron wave swing device has previously been presented as a possible candidate for a simple power conversion technique to the THz -domain. This paper gives a simulative estimation of the power conversion efficiency. The harmonic balance simulations use an equivalent circuit model, which is also derived in this work from a mechanical model. To verify the validity of the circuit model, current waveforms are compared to Monte Carlo simulations of identical setups. Model parameters are given for a wide range of device configurations. The device configuration exhibiting the most conforming waveform is used further for determining the best conversion efficiency. The corresponding simulation setup is described. Simulation results implying a conversion efficiency of about 22% are presented. (paper)
Schildbach, Christian; Ong, Duu Sheng; Hartnagel, Hans; Schmidt, Lorenz-Peter
2016-06-01
The ballistic electron wave swing device has previously been presented as a possible candidate for a simple power conversion technique to the THz -domain. This paper gives a simulative estimation of the power conversion efficiency. The harmonic balance simulations use an equivalent circuit model, which is also derived in this work from a mechanical model. To verify the validity of the circuit model, current waveforms are compared to Monte Carlo simulations of identical setups. Model parameters are given for a wide range of device configurations. The device configuration exhibiting the most conforming waveform is used further for determining the best conversion efficiency. The corresponding simulation setup is described. Simulation results implying a conversion efficiency of about 22% are presented.
Structure and apparent dispersion of ballistic plasma wave echoes of second order
The spatial structure of electron plasma wave echoes is investigated with special regard to the apparent dispersion, i.e. the relation between echo wavelength and frequency. The apparent dispersion is obtained by separately recording echo phase and amplitude, using an r.f.-interferometer combined with a network analyzer. Comparison with theory reveals the ballistic nature of the second order echoes investigated; due to the dispersion as a quantitative measure of the velocity diffusion, it yields furthermore a velocity-independent diffusion coefficient D2 = (1.5 +- 0.5) x 1017 m2 s-3, two orders of magnitude larger than expected from equilibrium theory. The enhanced velocity diffusion can be related to non-equilibrium fluctuations due to ion-acoustic turbulence present in the target plasma. (author)
1977-01-01
Two parameters, side on overpressure and side on impulse loads, and their application to the determination of structural damage to buildings and vehicles in the vicinity of an explosion are investigated. Special consideration was given to what constitutes damage and what level of damage is acceptable. Solutions were sorted through the examination of glass breakage, curve fit to bomb damage, overturning of marginal structures (buses, trucks, mobile homes) subject to toppling, and initiation of yielding in either beam or plate structural components. Three different empirical pressure versus impulse diagrams were presented - the first is for minor structural damage involving wrenched joints and partitions, the second is for major damage structural damage with load bearing members at least partially destroyed, and the third is for 50% to 75% of the building demolished. General guidelines were obtained from the results when the accurate structural details are unknown.
Elkarous, L.; Coghe, F.; Pirlot, M.; Golinval, J. C.
2013-09-01
This paper presents a study carried out with the commonly used experimental techniques of ballistic pressure measurement. The comparison criteria were the peak chamber pressure and its standard deviation inside specific weapon/ammunition system configurations. It is impossible to determine exactly how precise either crusher, direct or conformal transducer methods are, as there is no way to know exactly what the actual pressure is; Nevertheless, the combined use of these measuring techniques could improve accuracy. Furthermore, a particular attention has been devoted to the problem of calibration. Calibration of crusher gauges and piezoelectric transducers is paramount and an essential task for a correct determination of the pressure inside a weapon. This topic has not been completely addressed yet and still requires further investigation. In this work, state of the art calibration methods are presented together with their specific aspects. Many solutions have been developed to satisfy this demand; nevertheless current systems do not cover the whole range of needs, calling for further development effort. In this work, research being carried out for the development of suitable practical calibration methods will be presented. The behavior of copper crushers under different high strain rates by the use of the Split Hopkinson Pressure Bars (SHPB) technique is investigated in particular. The Johnson-Cook model was employed as suitable model for the numerical study using FEM code
This paper presents a study carried out with the commonly used experimental techniques of ballistic pressure measurement. The comparison criteria were the peak chamber pressure and its standard deviation inside specific weapon/ammunition system configurations. It is impossible to determine exactly how precise either crusher, direct or conformal transducer methods are, as there is no way to know exactly what the actual pressure is; Nevertheless, the combined use of these measuring techniques could improve accuracy. Furthermore, a particular attention has been devoted to the problem of calibration. Calibration of crusher gauges and piezoelectric transducers is paramount and an essential task for a correct determination of the pressure inside a weapon. This topic has not been completely addressed yet and still requires further investigation. In this work, state of the art calibration methods are presented together with their specific aspects. Many solutions have been developed to satisfy this demand; nevertheless current systems do not cover the whole range of needs, calling for further development effort. In this work, research being carried out for the development of suitable practical calibration methods will be presented. The behavior of copper crushers under different high strain rates by the use of the Split Hopkinson Pressure Bars (SHPB) technique is investigated in particular. The Johnson-Cook model was employed as suitable model for the numerical study using FEM code
J. N. Kapur
1960-04-01
Full Text Available In the present paper, an exact analytical solution of the equation of ballistics, for the specific case of a tubular charge has been given. This solution applies to some particular values, of the pressure-index alpha greater than unity, and for these values, the function G (gamma, alfa of Clemmow has also been explicitly determined.
Srebrenkoska, Vineta; Dimeski, Dimko; Spaseska, Dijana; Smileski, Rose
2003-01-01
The influence of molding pressure on blunt traume effect and ballistic strength of unidirectional and bidirectional composites based on UHMWPE (Ultra Hight Molecular Weight Polyethylene) fibers is investigated. Two types of unidirectional and one type of bidirectional composites molded at 20, 60 and 100 bar were tested on their ballistic strength and their blunt traume depth and area were measured. It was found out that by increasing the molding pressure the blunt trauma effect was decreas...
Wave effects on a pressure sensor
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...
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
Blast waves with cosmic-ray pressure
The effects of cosmic-ray pressure on the dynamics of self-similar, spherical blast waves and driven waves are investigated on the assumptions that the ratio of relativistic cosmic-ray pressure to total pressure at the shock front is a constant w and the the cosmic rays and thermal gas evolve as independent adiabatic fluids in the postshock flow. For blast waves from a point explosion in a uniform medium, the cosmic rays dominate the pressure near r = 0 if w>0. The solutions show that, if w is small, the ratio of cosmic-ray energy to total energy in the blast wave is several times w. The solutions are used to make specific predictions of the pion-decay γ-ray flux from a blast wave as a function of w. If w is large, the predicted fluxes from supernova remnants are close to the current observational limits. It is also noted that cosmic rays may limit the compression in the radiative shock waves of supernova remnants. The addition of cosmic pressure does not change the geneal nature of the driven wave self-similar solutions. The solutions are used to predict the pion-decay γ-ray flux from a young Type II supernova interacting with circumstellar material. Observations these γ-rays from extragalactic supernovae are not promising, but a galactic supernova could be very bright in γ-rays
Blast wave parameters at diminished ambient pressure
Silnikov, M. V.; Chernyshov, M. V.; Mikhaylin, A. I.
2015-04-01
Relation between blast wave parameters resulted from a condensed high explosive (HE) charge detonation and a surrounding gas (air) pressure has been studied. Blast wave pressure and impulse differences at compression and rarefaction phases, which traditionally determine damage explosive effect, has been analyzed. An initial pressure effect on a post-explosion quasi-static component of the blast load has been investigated. The analysis is based on empirical relations between blast parameters and non-dimensional similarity criteria. The results can be directly applied to flying vehicle (aircraft or spacecraft) blast safety analysis.
Transient flows and pressure waves in pipes
Transient laminar flows and pressure-wave propagations in pipes connected with components, commonly known as water hammer, are analyzed. The system studied consists of a constant-pressure vessel, a uniform circular pipe, a valve between them, and a receiver vessel. A pressure-wave equation and a linearized velocity equation are derived from the equations of mass and momentum conservation. Waveform distortion due to viscous dissipation and pipe-wall elastic expansion is characterized by a dimensionless transmission number, K. The coefficients of the damping of the pressure waves were found to be related to the roots of the Bessel function J0. An exact solution of the pressure-wave equation was obtained numerically. The relationship between the distortion of a traveling wave and the transmission number K was studied. The problem is also calculated with a general-purpose computer code, COMMIX, which solves the exact mass conservation equation and Navier-Stokes equations. The COMMIX calculational results agreed well with the analytical solutions
Metamaterials for Ballistic Electrons
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.
Modulated pressure waves in large elastic tubes.
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. PMID:24089964
Pressure measurements of nonplanar stress waves
A useful gage has been developed for measuring pressure of nonplanar or obliquely incident stress waves. The measurements made with these gages are not as precise as direct strain gage measurements, but are very good considering the conditions under which these gages are used. We feel a need to further develop our ability to measure nonplanar stress waves in the 0 to 10 kbar range. Carbon or ytterbium will probably be chosen for the sensing element
Propagation of Nonlinear Pressure Waves in Blood
Elgarayhi, A.; E. K. El-Shewy; MAHMOUD, ABEER A.; Elhakem, Ali A.
2013-01-01
The propagation of weakly nonlinear pressure waves in a fluid-filled elastic tube has been investigated. The reductive perturbation method has been employed to derive the Korteweg-de Vries equation for small but finite amplitude. The effect of the final inner radius of the tube on the basic properties of the soliton wave was discussed. Moreover, the conditions of stability and the soliton existence via the potential and the corresponding phase portrait were computed. The applicability of the ...
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...
Internal ballistics of recoilless high-low pressure guns using hepta-tubular powders
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.
K.S. Bhaskara Rao
1982-04-01
Full Text Available A review of the computations in Internal Ballistic Systems for developing pressure and velocity space curves, called primary problem and differential variations due to change in initial phase space of loading conditions, called secondary problem, is presented. In the concluding part, the general aspects of the secondary problem are analysed and reported.
K.S. Bhaskara Rao; Sharma, K. C.
1982-01-01
A review of the computations in Internal Ballistic Systems for developing pressure and velocity space curves, called primary problem and differential variations due to change in initial phase space of loading conditions, called secondary problem, is presented. In the concluding part, the general aspects of the secondary problem are analysed and reported.
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.
Rosenberg, Zvi
2012-01-01
This book covers the important issues of terminal ballistics in a comprehensive way combining experimental data, numerical simulations and analytical modeling. The first chapter reviews the experimental equipment which are used for ballistic tests and the diagnostics for material characterization under impulsive loading conditions. The second chapter covers essential features of the codes which are used for terminal ballistics such as the Euler vs. Lagrange schemes and meshing techniques, as well as the most popular material models. The third chapter, devoted to the penetration mechanics of rigid penetrators, brings the update of modeling in this field. The fourth chapter deals with plate perforation and the fifth chapter deals with the penetration mechanics of shaped charge jets and eroding long rods. The last two chapters discuss several techniques for the disruption and defeating of the main threats in armor design. Throughout the book the authors demonstrate the advantages of numerical simulations in unde...
Wave-induced pore water pressure in marine cohesive soils
无
2005-01-01
Cyclic triaxial tests and numerical analyses were undertaken, in order to evaluate the wave-induced pore water pressure in seabed sediments in the Hangzhou Bay. The cyclic triaxial tests indicate that the rate of pore water pressure generation in cohesive soils decreases with time, and the development of the pore water pressure can be represented by a hyperbolic curve. Numerical analyses, taking into account the generation and dissipation of pore water pressure simultaneously, suggest that the pore water pressure buildup in cohesive soils may increase with time continuously until the pore water pressure ratio approaches to 1, or it may decrease after a certain time, which is controlled by drain conditions. These phenomena are different from those in sands. For waves with a return period of 100 a in the Hangzhou Bay, ifthe wave duration is more than 60 h, then the pore water pressure ratio will be close to 1 and soil fabric failure will take place.
Surface wave propagation characteristics in atmospheric pressure plasma column
In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance
Surface wave propagation characteristics in atmospheric pressure plasma column
Pencheva, M.; Benova, E.; Zhelyazkov, I.
2007-04-01
In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.
Surface wave propagation characteristics in atmospheric pressure plasma column
Pencheva, M [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria); Benova, E [Department for Language Teaching and International Students, Sofia University, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria); Zhelyazkov, I [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria)
2007-04-15
In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency ({nu}/{omega}) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption {nu}/{omega} = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary {nu}/{omega}. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.
Numerical Study of Unsteady Supercavitation Perturbed by a Pressure Wave
Zheng, J. G.; Khoo, B. C.
2016-06-01
The unsteady features of supercavitation disturbed by an introduced pressure wave are investigated numerically using a one-fluid cavitation model. The supercavitating flow is assumed to be the homogeneous mixture of liquid and vapour which are locally under both kinetic and thermodynamic equilibrium. The compressibility effects of liquid water are taken into account to model the propagation of pressure wave through flow and its interaction with supercavitation bubble. The interaction between supercavity enveloping an underwater flat-nose cylinder and pressure wave is simulated and the resulting unsteady behavior of supercavitation is illustrated. It is observed that the supercavity will become unstable under the impact of the pressure wave and may collapse locally, which depends on the strength of perturbation. The huge pressure surge accompanying the collapse of supercavitation may cause the material erosion, noise, vibration and efficiency loss of operating underwater devices.
The Measurement and Analysis of Pressure Square Wave Generator
Investigating the dynamic characteristics is a significant study for actual hydraulic pressure system because the dynamic environment is used more often than static one. A dynamic pressure generator is called pressure square wave generator (PSWG) that developed in our team and generate square-like waveform and change testing pressure and frequency form 0.1 to 5 MPa and 12 to 2 KHz, respectively. In this study, dynamic performance of PSWG was investigated under different testing tangent velocity of rotor of PSWG including detailed transient response of a pressure square-like wave, rise time and deviation of magnitude. Results show that the tangent velocity of the rotor of PSWG affects the transient response of pressure square-like wave form. The desired transient response can be obtained when the tangent velocity is larger than 0.5 m/s. Furthermore, the larger the tangent velocity used, the smaller the rise time will be
Damping Pressure Pulsations in a Wave-Powered Desalination System
Padhye, Nikhil; Torres, James, Ph. D. Massachusetts Institute of Technology.; Thomas, Levon; Ljubicic, Dean M.; Kassner, Mortiz P.; Slocum, Alexander H.; Hopkins, Brandon James; Greenlee, Alison S.
2014-01-01
Wave-driven reverse osmosis desalination systems can be a cost-effective option for providing a safe and reliable source of drinking water for large coastal communities. Such systems usually require the stabilization of pulsating pressures for desalination purposes. The key challenge is to convert a fluctuating pressure flow into a constant pressure flow. To address this task, stub-filters, accumulators, and radially elastic-pipes are considered for smoothing the pressure fluctuations in the ...
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.
Fackler, M L
1986-12-01
Wound profiles made under controlled conditions in the wound ballistics laboratory at the Letterman Army Institute of Research showed the location along their tissue path at which projectiles cause tissue disruption and the type of disruption (crush from direct contact with the projectile or stretch from temporary cavitation). Comparison of wound profiles showed the fallacy in attempting to judge wound severity using velocity alone, and laid to rest the common belief that in treating a wound caused by a high-velocity missile, one needs to excise tissue far in excess of that which appears damaged. All penetrating projectile wounds, whether civilian or military, therefore should be treated the same regardless of projectile velocity. Diagnosis of the approximate amount and location of tissue disruption is made by physical examination and appropriate radiographic studies. These wounds are contaminated, and coverage with a penicillin-type antibiotic should be provided. PMID:3777618
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. PMID:26873972
Ultrahigh pressure laser-driven shock wave experiments
We review recent laser-driven shock wave experiments, with a view toward assessing the prospects of making accurate physical properties measurements at ultrahigh pressures. Recent experimental results on the scaling of shock pressure with laser intensity and wavelength are presented, and preliminary impedance matching experiments are discussed
Bender, D. F.
1978-01-01
The only ballistic trajectory mode feasible for a close solar probe or for an orbit inclined approximately 90 degrees to the ecliptic is the Jupiter gravity assisted mode. A comparison of the trajectories of the Solar Polar and the Solar Probe Mission for 1983 launches is shown. The geometry of the solar encounter phase is practically the same for the 4.3 year orbit achieved by a Jupiter gravity assist and for a one year orbit. Data describing the geometry of an orbit with perihelion at 4 solar radii and aphelion at Jupiter are listed. The range of apparent directions of the solar wind if it is flowing radially outward from the Sun with a speed of either 150 or 300 km/sec is shown. The minimum sun-earth-probe angle during the solar encounter as a function of the earth-node angle and the orbital inclination is also shown. If the inclination is 60 degrees or more, the minimum SEP angle is not greatly different from the 90 degree value.
Dual mode acoustic wave sensor for precise pressure reading
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.
Two distinct ballistic processes in graphene
A dynamical approach to ballistic transport in mesoscopic graphene samples of finite length Land contact potential difference with leads U is developed. It is shown that at ballistic times shorter than both relevant time scales, tL = L/vg (vg - Fermi velocity) and tu = ħ/(eU), the major effect of electric field is to creates the electron - hole pairs, namely causes interband transitions. At ballistic times lager than the two scales the mechanism is very different. The conductivity has its “nonrelativistic” or intraband value equal to the one obtained within the Landauer-Butticker approach for the barrier Uresulting from evanescent waves tunneling through the barrier.
Influence of ambient air pressure on impact pressure caused by breaking waves
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
Dynamic Wave Pressures on Deeply Embedded Large Cylindrical Structures due to Random Waves
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.
Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride
Hamlin, J.J.; Zocco, D.A.; Sayles, T.A.; Maple, M.B.; /UC, Davis; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.
2010-02-15
A series of high-pressure electrical resistivity measurements on single crystals of TbTe{sub 3} reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge density wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near {approx} 12.4 GPa.
Measurement of Blast Waves from Bursting Pressureized Frangible Spheres
Esparza, E. D.; Baker, W. E.
1977-01-01
Small-scale experiments were conducted to obtain data on incident overpressure at various distances from bursting pressurized spheres. Complete time histories of blast overpressure generated by rupturing glass spheres under high internal pressure were obtained using eight side-on pressure transducers. A scaling law is presented, and its nondimensional parameters are used to compare peak overpressures, arrival times, impulses, and durations for different initial conditions and sizes of blast source. The nondimensional data are also compared, whenever possible, with results of theoretical calculations and compiled data for Pentolite high explosive. The scaled data are repeatable and show significant differences from blast waves generated by condensed high-explosives.
Attenuation characteristics of nonlinear pressure waves propagating in pipes
Shih, C. C.
1974-01-01
A series of experiments was conducted to investigate temporal and spatial velocity distributions of fluid flow in 3-in. open-end pipes of various lengths up to 210 ft, produced by the propagation of nonlinear pressure waves of various intensities. Velocity profiles across each of five sections along the pipes were measured as a function of time with the use of hot-film and hot-wire anemometers for two pressure waves produced by a piston. Peculiar configurations of the velocity profiles across the pipe section were noted, which are uncommon for steady pipe flow. Theoretical consideration was given to this phenomenon of higher velocity near the pipe wall for qualitative confirmation. Experimentally time-dependent velocity distributions along the pipe axis were compared with one-dimensional theoretical results obtained by the method of characteristics with or without diffusion term for the purpose of determining the attenuation characteristics of the nonlinear wave propagation in the pipes.
Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; Harnafi, M.
2014-12-01
The westernmost Mediterranean comprises the Iberian Peninsula and Morocco, separated by the Alboran Sea and the Algerian Basin. From north to south this region consists of the Pyrenees, resulting from Iberia-Eurasia collision; the Iberian Massif, which has been undeformed since the end of the Paleozoic; the Central System and Iberian Chain, regions with intracontinental Oligocene-Miocene deformation; the Gibraltar Arc (Betics, Rif and Alboran terranes), resulting from post-Oligocene subduction roll-back; and the Atlas Mountains. We analyzed data from recent broad-band array deployments and permanent stations in the area (IberArray and Siberia arrays, the PICASSO array, the University of Munster array, and the Spanish, Portuguese and Moroccan National Networks) to characterize its lithospheric structure. The combined array of 350 stations has an average interstation spacing of ~60 km. We calculated the Rayleigh waves phase velocities from ambient noise (periods 4 to 40 s) and teleseismic events (periods 20 to 167 s). We inverted the phase velocities to obtain a shear velocity model for the lithosphere to ~200 km depth. Our results correlate well with the surface expression of the main structural units with higher crustal velocity for the Iberian Massif than for the Alpine Iberia and Atlas Mountains. The Gibraltar Arc has lower crustal shear velocities than the regional average at all crustal depths. It also shows an arc shaped anomaly with high upper mantle velocities (>4.6 km/s) at shallow depths (Atlas, the northeastern end of the Betic Mountains and the Late Cenozoic volcanic fields in Iberia and Morocco, indicative of high temperatures at relatively shallow depths, and suggesting that the lithosphere has been removed beneath these areas.
Calculations of pressure wave bursts in steam pipes
Using as an example the live steam system of a boiling water reactor, the pressure wave propagation phenomena resulting from turbine trips in response to the by-pass system are described. The results of a previous calculation, using linearised characteristics methods are compared with those of a calculation using a differential procedure based on results of measurements. In a second example the periodic operation of safety valves of the steam generating system of a sodium cooled reactor is studied. (orig.)
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...
Shock wave velocity and shock pressure for low density powders : A novel approach
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
SHOCK-WAVE VELOCITY AND SHOCK PRESSURE FOR LOW-DENSITY POWDERS - A NOVEL-APPROACH
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
Pressure wave model for action potential propagation in excitable cells
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 ...
Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves
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.
Nonlinear Modeling and Analysis of Pressure Wave inside CEUP Fuel Pipeline
Qaisar Hayat
2014-01-01
Full Text Available Operating conditions dependent large pressure variations are one of the working characteristics of combination electronic unit pump (CEUP fuel injection system for diesel engines. We propose a precise and accurate nonlinear numerical model of pressure inside HP fuel pipeline of CEUP using wave equation (WE including both viscous and frequency dependent frictions. We have proved that developed hyperbolic approximation gives more realistic description of pressure wave as compared to classical viscous damped wave equation. Frictional effects of various frequencies on pressure wave have been averaged out across valid frequencies to represent the combined effect of all frequencies on pressure wave. Dynamic variations of key fuel properties including density, acoustic wave speed, and bulk modulus with varying pressures have also been incorporated. Based on developed model we present analysis on effect of fuel pipeline length on pressure wave propagation and variation of key fuel properties with both conventional diesel and alternate fuel rapeseed methyl ester (RME for CEUP pipeline.
The Truth About Ballistic Coefficients
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.
Tunnel pressure waves - A smartphone inquiry on rail travel
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.
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.
Wave-Induced Pressure Under an Internal Solitary Wave and Its Impact at the Bed
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.
Electron density measurements of high pressure argon surface wave plasmas
The electron density of an argon standing surface wave plasma has been measured from Stark broadening of the hydrogen H/sub beta/ (4861A) line. The experimental setup, consisting of two coaxial cavities, was similar to that reported by Rogers and Asmussen. The plasma was generated by 45 watts per cavity of CW, 2.54 GHz microwave power in a 6 mm O.D. (4 mm I.D.) quartz tube. Experimental argon gas pressure varied from 50 torr to over one atmosphere. Small amounts (1-5%) of hydrogen added to the argon plasma were found to shorten the plasma by as much as 80%. Thus, the Stark measurements were made using trace amounts of hydrogen. The line width of H/sub beta/ was measured with a 1 meter Czerny-Turner grating spectrometer. The Stark broadening measurements revealed that the electron density is between 1013 and 1014 electrons/cc for a pressure range of 50 to 1000 torr. These measurements agree very well with the electron density determined from the wavelength of standing surface waves. The volume of the plasma was also measured photographically and average plasma power densities (absorbed power in the plasma divided by the plasma volume) was calculated
Wave-induced stresses and pore pressures near a mudline
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.
Internal wave pressure, velocity, and energy flux from density perturbations
Allshouse, Michael R.; Lee, Frank M.; Morrison, Philip J.; Swinney, Harry L.
2016-05-01
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 J =p u , which requires simultaneous measurements of the pressure and velocity perturbation fields p and u , respectively. We present a method for obtaining the instantaneous J (x ,z ,t ) from density perturbations alone: A Green's function-based calculation yields p ; 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 J is found to agree typically to within 1% with J computed directly using p and u from the Navier-Stokes simulation. We also apply the Green's function method to density perturbation data from laboratory schlieren measurements of internal waves in a stratified fluid and the result for J agrees to within 6 % with results from Navier-Stokes simulations. Our method for determining the instantaneous velocity, pressure, and energy flux fields applies to any system described by a linear approximation of the density perturbation field, e.g., to small-amplitude lee waves and propagating vertical modes. The method can be applied using our matlab graphical user interface EnergyFlux.
A Comparison of Measured and Predicted Wave-Impact Pressures from Breaking and Non-breaking Waves
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...
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.
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...
Internal ballistics of guns and rockets
Asim Ray
1964-07-01
Full Text Available An exact analytical solutions of the equations relating to the internals ballistics of guns and rockets in the non-isothermal model using tubular propellants which burns according to the pressure-index law has been obtained. An approximate solution to a pre-assigned level of accuracy has been presented.
Sychev, A. I.
2016-05-01
The effect of the initial pressure of multicomponent bubble media on the conditions of initiation, the structure, the velocity, and the pressure of detonation waves is experimentally studied. The variation of the initial pressure of a bubble medium is found to be an effective method to control the parameters of bubble detonation waves.
Mass Spectrometry of Atmospheric Pressure Surface Wave Discharges
Ridenti, M. A.; Souza-Corrêa, J. A.; Amorim, J.
2016-05-01
By applying mass spectrometry techniques, we carried out measurements of ionic mass spectrum and their energy distribution in order to investigate an atmospheric argon discharge by using a surfatron surface-wave device. The mass and energy distribution measurements were performed with fixed flow rate (2.5 SLM) of pure argon gas (99.999%) and different Ar-O2 gas mixture compositions (99-1, 98-2 and 97-3). The mass spectra and energy distributions were recorded for Ar+, O+, O+ 2, N+ and N2 +. The axial distribution profiles of ionic mass and their energy were obtained for different experimental conditions as a function of the plasma length. The results showed that the peak of the positive ion energy distributions shifted to higher energies and also that the distribution width increased as the distance between the sampling orifice and the launcher gap was increased. It was also found that under certain experimental conditions the ion flux of atomic species were higher than the ion flux of their diatomic counterpart. The motivation of this study was to obtain a better understanding of a surface wave discharge in atmospheric pressure that may play a key role on new second generation biofuel technologies.
Modeling internal ballistics of gas combustion guns.
Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias
2016-05-01
Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur. PMID:26239103
THE EFFECTS OF AREA CONTRACTION ON SHOCK WAVE STRENGTH AND PEAK PRESSURE IN SHOCK TUBE
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%.
Charge transport and shot noise in ballistic graphene sheet
Sonin, E. B.
2008-01-01
The current and the shot noise in a graphene sheet were analyzed in the ballistic regime for arbitrary voltage drops between leads and the sheet in the limit of infinite aspect ratio of the sheet width to its length, when quantization of transversal wave vectors is not essential. The cases of coherent and incoherent ballistic transport were compared. At high voltages the difference with coherent transport is not essential. But at low voltages conductance and Fano-factor dependences for incohe...
Ballistic electron transport in wrinkled superlattices
Mitran, T. L.; Nemnes, G. A.; Ion, L.; Dragoman, Daniela
2016-07-01
Inspired by the problem of elastic wave scattering on wrinkled interfaces, we studied the scattering of ballistic electrons on a wrinkled potential energy region. The electron transmission coefficient depends on both wrinkle amplitude and periodicity, having different behaviors for positive and negative scattering potential energies. For scattering on potential barriers, minibands appear in the electron transmission, as in superlattices, whereas for scattering on periodic potential wells the transmission coefficient has a more complex form. Besides suggesting that tuning of electron transmission is possible by modifying the scattering potential via voltages on wrinkled gate electrodes, our results emphasize the analogies between ballistic electrons and elastic waves even in scattering problems on non-typical configurations.
Calculation of pressure wave inside the steam line with turbine trip
After turbine trip, a pressure wave phenomenon happens inside the steam lines and has disadvantageous effects on the steam generator and steam lines. To study this effect, the mathematical models for pressure wave calculation are developed and the calculating results are analyzed
A mathematical model and numerical simulation of pressure wave in horizontal gas-liquid bubbly flow
HUANG Fei; BAI Bofeng; GUO Liejin
2004-01-01
By using an ensemble-averaged two-fluid model,with valid closure conditions of interfacial momentum exchange due to virtual mass force,viscous shear stress and drag force,a model for pressure wave propagation in a horizontal gas-liquid bubbly flow is proposed.According to the small perturbation theory and solvable condition of one-order linear uniform equations,a dispersion equation of pressure wave is induced.The pressure wave speed calculated from the model is compared and in good agreement with existing data.According to the dispersion equation,the propagation and attenuation of pressure wave are investigated systemically.The factors affecting pressure wave,such as void fraction,pressure,wall shear stress,perturbation frequency,virtual mass force and drag force,are analyzed.The result shows that the decrease in system pressure,the increase in void fraction and the existence of wall shear stress,will cause a decrease in pressure wave speed and an increase in the attenuation coefficient in the horizontal gas-liquid bubbly flow.The effects of perturbation frequency,virtual mass and drag force on pressure wave in the horizontal gas-liquid bubbly flow at low perturbation frequency are different from that at high perturbation frequency.
Thalen, E; Wit, H; Segenhout, H; Albers, F
2002-01-01
Inner ear pressure was measured in scala tympani with a micropipette during square wave pressure manipulation of the intracranial compartment and, subsequently, of the external ear canal (EEC) in the same guinea pig. As expected, the combination of the cochlear aqueduct and the inner ear behaves as
Influence of the initial pressure in bubble media on the detonation wave parameters
Sychev, A. I.
2015-04-01
The influence of the initial pressure in bubble media on the initiation, structure, velocity, and pressure of detonation waves in single-component bubble media is studied. The test medium (bubbles of a stoichiometric acetylene-oxygen mixture in a hydroglyceric solution) falls under the category of "chemically inactive liquid—bubbles of a chemically active gas." It is found that one can effectively control the parameters of bubble detonation waves by varying the initial pressure in the bubble medium.
Generation and propagation of pressure waves in supersonic deep-cavity flows
Handa, Taro; Ozaki, Takaya [Kyushu University, Department of Energy and Environmental Engineering, Kasuga City, Fukuoka (Japan); Miyachi, Hiroaki [Mitsubishi Heavy Industries, Power Systems Plant Engineering Department, Takasago, Hyogo (Japan); Kakuno, Hatsuki [Nippon Steel and Sumikin Engineering, Plant and Machinery Division, Kitakyushu, Fukuoka (Japan)
2012-12-15
The mechanism behind cavity-induced pressure oscillations in supersonic flows past a deep rectangular cavity is not well understood despite several investigations having been carried out. In particular, the process by which the pressure wave is generated and the path of the pressure wave propagating inside the cavity remains unclear. In the present study, the pressure waves around a deep rectangular cavity over which nitrogen gas flows at a Mach number of 1.7 are visualized using the schlieren method. The length of the cavity is 14.0 mm. The depths of the cavity are selected as 20.0 and 11.7 mm, corresponding to length-to-depth ratios of 0.70 and 1.2, respectively. The pressure waves propagating inside as well as outside the cavity have been successfully visualized using a high-speed camera, and the propagation pattern of these waves is found to be different from that previously predicted by numerical simulation and from those expected in previous oscillation models. In addition, the pressure oscillation near the trailing edge of the cavity is also measured using semiconductor-type pressure transducers simultaneously with the capture of the schlieren images. As a result, the relationship between the shear-layer motion, pressure-wave generation, and pressure oscillation at the trailing edge of the cavity is clarified experimentally. (orig.)
Rogue wave formation under the action of quasi-stationary pressure
Abrashkin, A. A.; Oshmarina, O. E.
2016-05-01
The process of rogue wave formation on deep water is considered. A wave of extreme amplitude is born against the background of uniform waves (Gerstner waves) under the action of external pressure on free surface. The pressure distribution has a form of a quasi-stationary "pit". The fluid motion is supposed to be a vortex one and is described by an exact solution of equations of 2D hydrodynamics for an ideal fluid in Lagrangian coordinates. Liquid particles are moving around circumferences of different radii in the absence of drift flow. Values of amplitude and wave steepness optimal for rogue wave formation are found numerically. The influence of vorticity distribution and pressure drop on parameters of the fluid is investigated.
Propagation of pore pressure diffusion waves in saturated dual-porosity media (II)
Yang, Duoxing; Li, Qi; Zhang, Lianzhong
2016-04-01
A mechanism has been established for pressure diffusion waves in dual-porosity media. Pressure diffusion waves are heavily damped with relatively low velocities and short wavelengths. The characteristic frequency dominates the attenuation behavior of pressure diffusions and separates wave fields into two asymptotic regimes: relaxed and unrelaxed. Characteristic delay times control the pressure diffusion between the matrix and the fractures. The transition zones in wavelength and attenuation peak shift toward high frequencies when the characteristic delay time decreases. In contrast, the transition zones in both phase and group velocity shift toward low frequencies as the characteristic time of the delay increases. In a spatially dependent diffusivity field, the pressure diffusion waves in dual-porosity media obey an accumulation-depletion law.
Pressure increase in two-phase media behind air shock waves and by shock wave accelerated pistons
Patz, G.; Smeets, G.
Results are summarized from experimental and theoretical studies of the effects of a shock wave on a two-phase medium (TPM) and the compression of a TPM by a piston accelerated by the pressure behind a reflected shock. Attention is also given to the use of foam as the TPM and actions of the changing pressure as the shock moves to the end of the shock tube and returns. The situation is extended to the situation where the returning wave drives a piston into the foam. Analysis of the pressure variations in the foam shows that the peak pressure will depend only on the piston pressure. No shocks formed in the TMP, either in the model predictions or in an experimental validation, because the piston speed was always well below the sonic velocity in the lather.
Role of the vertical pressure gradient in wave boundary layers
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 pressure...... gradient is also treated as any other turbulence quantity like velocity fluctuations and statistical properties of the vertical pressure gradient are calculated from the DNS data. The presence of a vertical pressure gradient in the near bed region has significant implications for sediment transport....
Campana, Mylène; Laumond, Jean-Paul
2016-01-01
This paper addresses the motion planning problem for a jumping point-robot. Each jump consists in a ballistic motion linking two positions in contact with obstacle surfaces. A solution path is thus a sequence of parabola arcs. The originality of the approach is to consider non-sliding constraints at contact points: slipping avoidance is handled by constraining takeoff and landing velocity vectors to belong to 3D friction cones. Furthermore the magnitude of these velocities is bounded. A balli...
王育维; 郭映华; 董彦诚; 张洪汉
2016-01-01
An analysis is made of the interior ballistics structural characteristics of low-zone in Bi-modular charge. In response to the problem of much more prominent pressure wave of zone 2,a two-phase and one-dimensional model of interior ballistics was built with combustible case combustion law provided. An analysis is made of the effects of combustible case energy parameter on pressure waves. Through the comparative experimental study of different energy combustible cases and theoretical simu-lation analysis of interior ballistics multiphase flow,the effect laws of combustible case energy parame-ter on zone 2 pressure waves was obtained. Great agreement is shown between model and experimental measurements. The study results can serve as a guideline for pressure wave and optimizing combustible case energy parameter of zone 2 in Bi-modular charge.%分析了双元模块装药小号装药的结构特点，针对小号装药的2号装药压力波现象较为突出的问题，建立了双一维多相流内弹道模型，给出了可燃容器燃烧规律，分析了可燃容器能量参数对压力波的影响。通过对可燃容器不同能量参数的对比试验研究及利用多相流内弹道理论仿真分析，得到了可燃容器能量特性对2号装药压力波的影响规律，理论仿真结果与试验结果一致，为分析小号装药压力波现象及可燃容器参数优化设计提供一定参考。
The EUROGAM data-acquisition has to handle a large number of events/s. Typical in-beam experiments using heavy-ion fusion reactions assume the production of about 50 000 compound nuclei per second deexciting via particle and γ-ray emissions. The very powerful γ-ray detection of EUROGAM is expected to produce high-fold event rates as large as 104 events/s. Such high count rates introduce, in a common dead time mode, large dead times for the whole system associated with the processing of the pulse, its digitization and its readout (from the preamplifier pulse up to the readout of the information). In order to minimize the dead time the shaping time constant τ, usually about 3 μs for large volume Ge detectors has to be reduced. Smaller shaping times, however, will adversely affect the energy resolution due to ballistic deficit. One possible solution is to operate the linear amplifier, with a somewhat smaller shaping time constant (in the present case we choose τ = 1.5 μs), in combination with a ballistic deficit compensator. The ballistic deficit can be corrected in different ways using a Gated Integrator, a hardware correction or even a software correction. In this paper we present a comparative study of the software and hardware corrections as well as gated integration
Bullet Retarding Forces in Ballistic Gelatin by Analysis of High Speed Video
Gaylord, Steven; Courtney, Michael; Courtney, Amy
2013-01-01
Though three distinct wounding mechanisms (permanent cavity, temporary cavity, and ballistic pressure wave) are described in the wound ballistics literature, they all have their physical origin in the retarding force between bullet and tissue as the bullet penetrates. If the bullet path is the same, larger retarding forces produce larger wounding effects and a greater probability of rapid incapacitation. By Newton's third law, the force of the bullet on the tissue is equal in magnitude and opposite in direction to the force of the tissue on the bullet. For bullets penetrating with constant mass, the retarding force on the bullet can be determined by frame by frame analysis of high speed video of the bullet penetrating a suitable tissue simulant such as calibrated 10% ballistic gelatin. Here the technique is demonstrated with 9mm NATO bullets, 32 cm long blocks of gelatin, and a high speed video camera operating at 20,000 frames per second. It is found that different 9mm NATO bullets have a wide variety of pot...
Using Clifford Algebra to Understand the Nature of Negative Pressure Waves
McClellan, Gene
2014-03-01
The geometric algebra of 3-D Euclidean space, a sub-discipline of Clifford algebra, is a useful tool for analyzing wave propagation. We use geometric algebra to explore the concept of negative pressure. In free space a straightforward extension of Maxwell's equations using geometric algebra yields a theory in which classical electromagnetic waves coexist with nonelectromagnetic waves having retrograde momentum. By retrograde momentum we mean waves carrying momentum pointing in the opposite direction of energy flow. If such waves exist, they would have negative pressure. In rebounding from a wall, they would pull rather than push. In this presentation we use standard methods of analyzing energy and momentum conservation and their flow through the surface of an enclosed volume to illustrate the properties of both the electromagnetic and nonelectromagnetic solutions of the extended Maxwell equations. The nonelectromagnetic waves consist of coupled scalar and electric waves and coupled magnetic and pseudoscalar waves. They superimpose linearly with electromagnetic waves. We show that the nonelectromagnetic waves, besides having negative pressure, propagate with the speed of light and do not interact with conserved electric currents. Hence, they have three properties in common with dark energy.
Survivability Armor Ballistic Laboratory (SABL)
Federal Laboratory Consortium — The SABL provides independent analysis, ballistic testing, data collection, data reduction and qualification of current and advanced armors. Capabilities: The SABL...
Naidu, M.U.R; C Prabhakar Reddy
2012-01-01
Objective: The aim of the present study was to validate and compare novel methods to determine aortic blood pressure non-invasively based on Oscillometric Pulse Wave Velocity (PWV) measurement using four limb-cuff pressure waveforms and two lead Electrocardiogram (ECG) with a validated tonometric pulse wave analysis system in patients. Materials and Methods: After receiving the consent, in 49 patients with hypertension, coronary artery disease, diabetes mellitus, PWV, and central blood p...
Mohiuddin, Mohammad W.; Rihani, Ryan J.; Laine, Glen A.; Quick, Christopher M.
2012-01-01
The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (Ctot) and increases in total peripheral resistance (Rtot) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because increases in pulse wave velocity (cph) make the reflected pressure wave arrive earlier, augmenting systol...
Measuring high pressure equation of state of polystyrene using laser driven shock wave
Shu, Hua; Huang, Xiuguang; Ye, Junjian; Wu, Jiang; Jia, Guo; Fang, Zhiheng; Xie, Zhiyong; Zhou, Huazhen; Fu, Sizu
2015-11-01
High precision polystyrene equation of state data were measured using laser-driven shock waves with pressures from 180 GPa to 700 GPa. α quartz was used as standard material, the shock wave trajectory in quartz and polystyrene was measured using the Velocity Interferometer for Any Reflector (VISAR). Instantaneous shock velocity in quartz and polystyrene was obtained when the shock wave pass the interface. This provided ~1% precision in shock velocity measurements.
Measuring high pressure equation of state of polystyrene using laser driven shock wave
High precision polystyrene equation of state data were measured using laser-driven shock waves with pressures from 180 GPa to 700 GPa. Alpha quartz was used as standard material, the shock wave trajectory in quartz and polystyrene was measured using the Velocity Interferometer for Any Reflector (VISAR). Instantaneous shock velocity in quartz and polystyrene was obtained when the shock wave pass the interface. This provided ∼1% precision in shock velocity measurements. (authors)
Remya, B.; Tsurutani, B. T.; Reddy, R. V.; Lakhina, G. S.; Hajra, R.
2015-09-01
Electromagnetic ion (proton) cyclotron (EMIC) waves and whistler mode chorus are simultaneously detected in the Earth's dayside subsolar outer magnetosphere. The observations were made near the magnetic equator 3.1°-1.5° magnetic latitude at 1300 magnetic local time from L = 9.9 to 7.0. It is hypothesized that the solar wind external pressure caused preexisting energetic 10-100 keV protons and electrons to be energized in the T⊥ component by betatron acceleration and the resultant temperature anisotropy (T⊥>T∥) formed led to the simultaneous generation of both EMIC (ion) and chorus (electron) waves. The EMIC waves had maximum wave amplitudes of ˜6 nT in a ˜60 nT ambient field B0. The observed EMIC wave amplitudes were about ˜10 times higher than the usually observed chorus amplitudes (˜0.1-0.5 nT). The EMIC waves are found to be coherent to quasi-coherent in nature. Calculations of relativistic ˜1-2 MeV electron pitch angle transport are made using the measured wave amplitudes and wave packet lengths. Wave coherency was assumed. Calculations show that in a ˜25-50 ms interaction with an EMIC wave packet, relativistic electron can be transported ˜27° in pitch. Assuming dipole magnetic field lines for a L = 9 case, the cyclotron resonant interaction is terminated ˜±20° away from the magnetic equator due to lack of resonance at higher latitudes. It is concluded that relativistic electron anomalous cyclotron resonant interactions with coherent EMIC waves near the equatorial plane is an excellent loss mechanism for these particles. It is also shown that E > 1 MeV electrons cyclotron resonating with coherent chorus is an unlikely mechanism for relativistic microbursts. Temporal structures of ˜30 keV precipitating protons will be ˜2-3 s which will be measurable at the top of the ionosphere.
Analysis of pressure waves in the cone-type combustion chamber under SI engine knock
Highlights: • A 3D numerical model is conducted to investigate the shock waves in the engine knock. • Overpressure distribution on the top piston surface is caught while knocking. • Numerical simulation shows that shock waves converge in the combustion chamber. • The converged shock waves damage piston during severe knock. - Abstract: For the internal-combustion engine, super knock produced by the engine downsizing technology induces severe oscillations in a combustion chamber, which may damage the piston. In this work, 3D numerical simulation is used to study the propagation and reflection of pressure waves produced in the cone roof type combustion chamber. Overpressure distribution of top piston surface is caught. Numerical simulation shows that the pressure waves are amplified in a special zone because of the shape of the combustion chamber, which induces the overpressure much higher than that in other zones. The numerical results are validated by the damaged pistons. It is found that the converged pressure waves could be the reason which causes damage in the local region of the piston under super knock. The results obtained in the study provide assistance in the design of combustion chamber shape in order to avoid piston destroyed by the pressure waves
This review describes the ballistic quality assurance for stereotactic intracranial irradiation treatments delivered with Gamma KnifeR either dedicated or adapted medical linear accelerators. Specific and periodic controls should be performed in order to check the mechanical stability for both irradiation and collimation systems. If this step remains under the responsibility of the medical physicist, it should be done in agreement with the manufacturer's technical support. At this time, there are no recent published guidelines. With technological developments, both frequency and accuracy should be assessed in each institution according to the treatment mode: single versus hypo-fractionated dose, circular collimator versus micro-multi-leaf collimators. In addition, 'end-to-end' techniques are mandatory to find the origin of potential discrepancies and to estimate the global ballistic accuracy of the delivered treatment. Indeed, they include frames, non-invasive immobilization devices, localizers, multimodal imaging for delineation and in-room positioning imaging systems. The final precision that could be reasonably achieved is more or less 1 mm. (authors)
On the recovery of traveling water waves with vorticity from the pressure at the bed
Hur, Vera Mikyoung
2015-01-01
We propose higher-order approximation formulae recovering the surface elevation from the pressure at the bed and the background shear flow for small-amplitude Stokes and solitary water waves. They offer improvements over the pressure transfer function and the hydrostatic approximation. The formulae compare reasonably well with asymptotic approximations of the exact relation between the pressure at the bed and the surface wave in the zero vorticity case, but they incorporate the effects of vorticity through solutions of the Rayleigh equation. Several examples are discussed.
Energy transfer from a laser pulse to a blast wave in reduced-pressure air atmospheres
Focusing a transversely excited atmospheric CO2 laser beam in air atmospheres induced a blast wave. The kinetic energy of a laser-induced blast wave was determined from shadowgraph images of shock wave expansion. Results showed that the fraction of input laser energy that is converted into the blast wave energy decreased from 0.45 to 0.2 concomitant with the decrease in ambient pressure from 100 to 10 kPa. Also, it was insensitive to input laser energy from 4 to 13 J
Rubber-induced uniform laser shock wave pressure for thin metal sheets microforming
Highlights: • The rubber is introduced to smooth laser shock wave pressure. • The mechanism of rubber-induced smoothing effect is proposed. • Smoothing effect is mainly due to the radial expansion of plasma cloud on rubber. • The good surface quality can be obtained under rubber dynamic loading. - Abstract: Laser shock microforming of thin metal sheets is a new high velocity forming technique, which employs laser shock wave to deform the thin metal sheets. The spatial distribution of forming pressure is mainly dependent on the laser beam. A new type of laser shock loading method is introduced which gives a uniform pressure distribution. A low density rubber is inserted between the laser beam and the thin metal sheets. The mechanism of rubber-induced smoothing effect on confined laser shock wave is proposed. Plasticine is used to perform the smoothing effect experiments due to its excellent material flow ability. The influence of rubber on the uniformity of laser shock wave pressure is studied by measuring the surface micro topography of the deformed plasticine. And the four holes forming experiment is used to verify the rubber-induced uniform pressure on thin metal sheets surface. The research results show the possibility of smoothing laser shock wave pressure using rubber. And the good surface quality can be obtained under rubber dynamic loading
Quantification of wave reflection in the human aorta from pressure alone: a proof of principle.
Westerhof, Berend E; Guelen, Ilja; Westerhof, Nico; Karemaker, John M; Avolio, Alberto
2006-10-01
Wave reflections affect the proximal aortic pressure and flow waves and play a role in systolic hypertension. A measure of wave reflection, receiving much attention, is the augmentation index (AI), the ratio of the secondary rise in pressure and pulse pressure. AI can be limiting, because it depends not only on the magnitude of wave reflection but also on wave shapes and timing of incident and reflected waves. More accurate measures are obtainable after separation of pressure in its forward (P(f)) and reflected (P(b)) components. However, this calculation requires measurement of aortic flow. We explore the possibility of replacing the unknown flow by a triangular wave, with duration equal to ejection time, and peak flow at the inflection point of pressure (F(tIP)) and, for a second analysis, at 30% of ejection time (F(t30)). Wave form analysis gave forward and backward pressure waves. Reflection magnitude (RM) and reflection index (RI) were defined as RM=P(b)/P(f) and RI=P(b)/(P(f)+P(b)), respectively. Healthy subjects, including interventions such as exercise and Valsalva maneuvers, and patients with ischemic heart disease and failure were analyzed. RMs and RIs using F(tIP) and F(t30) were compared with those using measured flow (F(m)). Pressure and flow were recorded with high fidelity pressure and velocity sensors. Relations are: RM(tIP)=0.82RM(mf)+0.06 (R(2)=0.79; n=24), RM(t30)=0.79RM(mf)+0.08 (R(2)=0.85; n=29) and RI(tIP)=0.89RI(mf)+0.02 (R(2)=0.81; n=24), RI(t30)=0.83RI(mf)+0.05 (R(2)=0.88; n=29). We suggest that wave reflection can be derived from uncalibrated aortic pressure alone, even when no clear inflection point is distinguishable and AI cannot be obtained. Epidemiological studies should establish its clinical value. PMID:16940207
Low-pressure sustainment of surface-wave microwave plasma with modified microwave coupler
Sasai, Kensuke; Suzuki, Haruka; Toyoda, Hirotaka
2016-01-01
Sustainment of long-scale surface-wave plasma (SWP) at pressures below 1 Pa is investigated for the application of the SWP as an assisting plasma source for roll-to-roll sputter deposition. A modified microwave coupler (MMC) for easier surface-wave propagation is proposed, on the basis of the concept of the power direction alignment of the slot antenna and surface-wave propagation. The superiority of the MMC-SWP over conventional SWPs is shown at a sustainment pressure as low as 0.6 Pa and an electron density as high as 3 × 1017 m-3. A polymer film is treated with the MMC-SWP at a low pressure of 0.6 Pa, and surface modification at a low pressure is proved using Ar plasma. These results show the availability of the MMC-SWP as the surface treatment plasma source that is compatible with sputter deposition in the same processing chamber.
Chorowski, M.; Grabowski, M.; Jędrusyna, A.; Wach, J.
Helium inventory in high energy accelerators, tokamaks and free electron lasers may exceed tens of tons. The gaseous helium is stored in steel tanks under a pressure of about 20 bar and at environment temperature. Accidental rupture of any of the tanks filled with the gaseous helium will create a rapid energy release in form of physical blast. An estimation of pressure wave distribution following the tank rupture and potential consequences to the adjacent research infrastructure and buildings is a very important task, critical in the safety aspect of the whole cryogenic system. According to the present regulations the TNT equivalent approach is to be applied to evaluate the pressure wave following a potential gas storage tank rupture. A special test stand was designed and built in order to verify experimentally the blast effects in controlled conditions. In order to obtain such a shock wave a pressurized plastic tank was used. The tank was ruptured and the resulting pressure wave was recorded using a spatially-distributed array of pressure sensors connected to a high-speed data acquisition device. The results of the experiments and the comparison with theoretical values obtained from thermodynamic model of the blast are presented. A good agreement between the simulated and measured data was obtained. Recommendations regarding the applicability of thermodynamic model of physical blast versus TNT approach, to estimate consequences of gas storage tank rupture are formulated. The laboratory scale experimental results have been scaled to ITER pressurized helium storage tanks.
Increased hepatic venous pressure can be observed in patients with advanced liver disease and congestive heart failure. This elevated portal pressure also leads to variation in acoustic radiation-force-derived shear wave-based liver stiffness estimates. These changes in stiffness metrics with hepatic interstitial pressure may confound stiffness-based predictions of liver fibrosis stage. The underlying mechanism for this observed stiffening behavior with pressurization is not well understood and is not explained with commonly used linear elastic mechanical models. An experiment was designed to determine whether the stiffness increase exhibited with hepatic pressurization results from a strain-dependent hyperelastic behavior. Six excised canine livers were subjected to variations in interstitial pressure through cannulation of the portal vein and closure of the hepatic artery and hepatic vein under constrained conditions (in which the liver was not free to expand) and unconstrained conditions. Radiation-force-derived shear wave speed estimates were obtained and correlated with pressure. Estimates of hepatic shear stiffness increased with changes in interstitial pressure over a physiologically relevant range of pressures (0–35 mmHg) from 1.5 to 3.5 m s−1. These increases were observed only under conditions in which the liver was free to expand while pressurized. This behavior is consistent with hyperelastic nonlinear material models that could be used in the future to explore methods for estimating hepatic interstitial pressure noninvasively. (paper)
Influence of dielectric barrier discharges on low Mach number shock waves at low to medium pressures
For shock wave propagation in nonequilibrium plasmas, it has been shown that when the electron Debye length exceeds the shock wave discontinuity dimension, strong double layers are generated, propagating with the shock wave. Strong double layer formation leads to the enhancement of the local excitation, ionization, and local neutral gas heating which increases the shock wave velocity. It is shown that dielectric barrier discharges (DBD) in pure N2 also increase the shock wave velocity and broaden the shock wave. The DBD is considerably more energy efficient in producing these effects compared to a dc glow discharge and can operate over a wide pressure range. It is shown that these effects are also operative in the pure N2 discharge afterglow, allowing a wide range of pulse repetition frequencies
A new method to record subglottal pressure waves : potential applications
Neumann, K; Gall, [No Value; Schutte, HK; Miller, DG
2003-01-01
Rapid subglottal pressure changes related to the glottal cycles influence the aerodynamics of phonation. Various methods to measure these have been developed, but are not practical for routine phoniatric use. For that reason, a noninvasive measurement tool is necessary. This article presents a techn
Analytical evaluation of special numerical calculations of pressure waves in the fluid. Pt. 1
The practise of applying control calculations to the results of extensive numerical calculations in the field of scientific engineering is indispensable, especially with regard to safety assessments. Analytical methods are often best suited for this purpose. Furthermore, they allow developing a sound understanding of the physical processes involved. This also applies to several methods for determining the pressure behavior inside a fluid. In the present report, the results of calculations are checked by the method of the so-called one-dimensional wave propagation. It is presumed that the propagation of the pressure wave in a fluid-filled system can be closely approximated by a function which, in addition to time and other parameters depends only on the coordinate of the direction of wave propagation. Satisfactory approximations are obtained wherever the averaging of certain parameters in the direction perpendicular to the direction of propagation is sufficient with regard to the mathematical evaluation of essential effects. The examples presented in this report start with approximative descriptions of non-linear effects in pressure waves. Starting from a certain location and point in time, the pressure waves have a linear characteristic. This is because pressure pulses introduced into the fluid are usually dampened to a considerable extent. Going backward in time, perturbation calculations can then be carried out. Certain aspects of the resulting approximation are well suited to check the results of extensive numerical calculations. The comparisons presented show good to reasonable results. (orig./GL)
Lin, Yuanhua; Kong, Xiangwei; Qiu, Yijie; Yuan, Qiji
2013-01-01
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 tw...
Operating process optimization in a ballistic plasmatron with multistage heating
The study on operating modes of ballistic plasmatrons is carried out. Optimization parameters and operating modes of these devices made it possible to increase by 10-20 times their efficiency. The energy characteristics achieved as well as self-regulation and high coefficient of the pushing gas energy conversion into the plasma emission energy in the optical and ultraviolet wave ranges (up to 30% in real experimental devices) enable the extension of the application area of the sources of the optical and ultraviolet radiation on the basis of ballistic plasmatrons
Quantum Interference and Ballistic Transmission in Nanotube Electron Waveguides
The electron transport properties of well-contacted individual single-walled carbon nanotubes are investigated in the ballistic regime. Phase coherent transport and electron interference manifest as conductance fluctuations as a function of Fermi energy. Resonance with standing waves in finite-length tubes and localized states due to imperfections are observed for various Fermi energies. Two units of quantum conductance 2G0=4e2/h are measured for the first time, corresponding to the maximum conductance limit for ballistic transport in two channels of a nanotube
A computational study of pressure wave reflections in the pulmonary arteries.
Qureshi, M Umar; Hill, N A
2015-12-01
Experiments using wave intensity analysis suggest that the pulmonary circulation in sheep and dogs is characterized by negative or open-end type wave reflections, that reduce the systolic pressure. Since the pulmonary physiology is similar in most mammals, including humans, we test and verify this hypothesis by using a subject specific one-dimensional model of the human pulmonary circulation and a conventional wave intensity analysis. Using the simulated pressure and velocity, we also analyse the performance of the P-U loop and sum of squares techniques for estimating the local pulse wave velocity in the pulmonary arteries, and then analyse the effects of these methods on linear wave separation in the main pulmonary artery. P-U loops are found to provide much better estimates than the sum of squares technique at proximal locations, but both techniques accumulate progressive error at distal locations away from heart, particularly near junctions. The pulse wave velocity estimated using the sum of squares method also gives rise to an artificial early systolic backward compression wave. Finally, we study the influence of three types of pulmonary hypertension viz. pulmonary arterial hypertension, chronic thromboembolic pulmonary hypertension and pulmonary hypertension associated with hypoxic lung disease. Simulating these conditions by changing the relevant parameters in the model and then applying the wave intensity analysis, we observe that for each group the early systolic backward decompression wave reflected from proximal junctions is maintained, whilst the initial forward compression and the late systolic backward compression waves amplify with increasing pathology and contribute significantly to increases in systolic pressure. PMID:25754476
Marini, F; Mangiante, G; Dagradi, V; Radin, S; Carolo, F; Giarolli, M; Della Giacoma, G; Tosi, D; Merico, G; Tenci, A
1993-01-01
This brief chapter, focusing essentially on a single topic, has been written in homage to Emile Theodor Kocker, a masterful exponent of the art of surgery and founder of the culture of terminal ballistics. For most of the literature we are indebted to Fackler and Dougherty, who, with the particular grasp, and fair of historians, act as guides on a trial which is only apparently retrograde, but which actually bears eloquent witness to the fact that even in the most physically tangible of arts, namely the art of surgery, inspired curiosity may help us to go well beyond the limits of our day and age. This chapter is also dedicated to the memory of another great surgeon, Vittorio Pettinari, who for one of the authors was an incomparable mentor and past-master of such curiosity. PMID:7923495
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.
Vertical pressure gradient and particle motions in wave boundary layers
Jensen, Karsten Lindegård
is a function of phase. Therefore the particle will settle towards the end of each half period, and after flow reversal, when the turbulent intensity becomes large enough it can be suspended. If the particle is light enough it can be maintained in suspension, otherwise it will settle before it is....... 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 weight of sediment. This revels that the upward directed vertical pressure gradient on average has a magnitude that yields in a contribution to the force needed to overcome the submerged weight of the water-sediment mixture. Secondly particle motion in the oscillatory boundary layer is...
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....
Pressure dependence of the charge-density-wave gap in rare-earth tritellurides.
Sacchetti, A; Arcangeletti, E; Perucchi, A; Baldassarre, L; Postorino, P; Lupi, S; Ru, N; Fisher, I R; Degiorgi, L
2007-01-12
We investigate the pressure dependence of the optical properties of CeTe3, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the midinfrared 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 RTe3. PMID:17358625
Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides
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}.
Pressure dependence of the charge-density-wave gap in rare-earth tri-tellurides
A. Sacchetti; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P.; Lupi, S.; Ru, N.; Fisher, I. R.; Degiorgi, L.
2006-01-01
We investigate the pressure dependence of the optical properties of CeTe$_3$, 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 com...
Analysis of behind the armor ballistic trauma.
Wen, Yaoke; Xu, Cheng; Wang, Shu; Batra, R C
2015-05-01
The impact response of body armor composed of a ceramic plate with an ultrahigh molecular weight polyethylene (UHMWPE) fiber-reinforced composite and layers of UHMWPE fibers shielding a block of ballistic gelatin has been experimentally and numerically analyzed. It is a surrogate model for studying injuries to human torso caused by a bullet striking body protection armor placed on a person. Photographs taken with a high speed camera are used to determine deformations of the armor and the gelatin. The maximum depth of the temporary cavity formed in the ballistic gelatin and the peak pressure 40mm behind the center of the gelatin front face contacting the armor are found to be, respectively, ~34mm and ~15MPa. The Johnson-Holmquist material model has been used to simulate deformations and failure of the ceramic. The UHMWPE fiber-reinforced composite and the UHMWPE fiber layers are modeled as linear elastic orthotropic materials. The gelatin is modeled as a strain-rate dependent hyperelastic material. Values of material parameters are taken from the open literature. The computed evolution of the temporary cavity formed in the gelatin is found to qualitatively agree with that seen in experiments. Furthermore, the computed time histories of the average pressure at four points in the gelatin agree with the corresponding experimentally measured ones. The maximum pressure at a point and the depth of the temporary cavity formed in the gelatin can be taken as measures of the severity of the bodily injury caused by the impact; e.g. see the United States National Institute of Justice standard 0101.06-Ballistic Resistance of Body Armor. PMID:25676500
Smith, N; P Zhong
2012-01-01
To investigate the roles of lithotripter shock wave (LSW) parameters and cavitation in stone comminution, a series of in vitro fragmentation experiments have been conducted in water and 1,3-butanediol (a cavitation-suppressive fluid) at a variety of acoustic field positions of an electromagnetic shock wave lithotripter. Using field mapping data and integrated parameters averaged over a circular stone holder area (Rh = 7 mm), close logarithmic correlations between the average peak pressure (P+...
Molecular modeling of high-pressure ramp waves in tantalum
Lane, J. Matthew D.; Lim, Hojun; Brown, Justin L.
2015-03-01
Ramp wave compression experiments of bcc metals under extreme conditions have produced differing measurements of material strength response. These variations are often attributed to differing experimental techniques, and varying material factors such as microstructure, and strain-rate. We present non-equilibrium molecular dynamics simulations of tantalum for single crystal and two polycrystalline nanostructures out to 250 GPa, over strain states ranging from 108 to 1011 1/s. Results will be compared to recent Z-machine strength experiments, meso-scale crystal plasticity models and continuum-scale polycrystalline model. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Wave pattern in the wake of an arbitrary moving surface pressure disturbance
Miao, Sha; Liu, Yuming
2015-12-01
We study the problem of wave pattern in the wake of an arbitrary surface pressure disturbance that moves forward at constant speed U in deep water. We seek the dependence of the location of the maximum amplitude of waves upon the pressure distribution and the Froude number F ≡ U / √{ g L } , where L is the characteristic length of the pressure disturbance and g is the gravitational acceleration. We show by theoretical analysis and direct numerical evaluation that half of the included angle (ϕmax) of the V-shape corresponding to the maximum amplitude of the waves in the wake at large Froude numbers behaves asymptotically as ϕ max = C F - a for F > F c , with the constant a, coefficient C, and threshold value of Froude number F c all being functions of the pressure distribution. It is found that for most pressure disturbances, a equals 1, but a can equal 2 for special non-smooth pressure disturbances. The condition in terms of the order of discontinuity and distribution shape of the pressure disturbance for the result of a = 2 is provided. These findings imply that for ship wakes, ϕmax generally decreases with increasing F at large Froude numbers, while the exact value of ϕmax is dependent on ship geometry and F .
Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves
Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ηbw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case. (paper)
Ballistic studies on layered structures
This paper presents the ballistic behavior and penetration mechanism of metal-metal and metal-fabric layered structures against 7.62 armour piercing projectiles at a velocity of 840 ± 15 m/s at 30o angle of impact and compares the ballistic results with that of homogeneous metallic steel armour. This study also describes the effect of keeping a gap between the target layers. Experimental results showed that among the investigated materials, the best ballistic performance was attained with metal-fabric layered structures. The improvements in ballistic performance were analyzed in terms of mode of failure and fracture mechanisms of the samples by using optical and electron microscope, X-ray radiography and hardness measurement equipments.
Internal Ballistics of Recoilless Guns
Asim Ray
1967-01-01
Full Text Available A new method for calculating the ballistics of recoilless guns during the period of burning of the propellant has been obtained. Ballistics have also been calculated by exact numerical integration in a few cases and these results have been compared with those obtained by the method described in this paper. It has been found that the results obtained by these two methods agree satisfactorily.
Decoherence in ballistic mesoscopic interferometers
Seelig, Georg; Pilgram, Sebastian; Buttiker, Markus
2003-01-01
We provide a theoretical explanation for two recent experiments on decoherence of Aharonov-Bohm oscillations in two- and multi-terminal ballistic rings. We consider decoherence due to charge fluctuations and emphasize the role of charge exchange between the system and the reservoir or nearby gates. A time-dependent scattering matrix approach is shown to be a convenient tool for the discussion of decoherence in ballistic conductors.
The Oblique Incident Effects of Electromagnetic Wave in Atmospheric Pressure Plasma Layers
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.
Modeling and simulation of pressure waves generated by nano-thermite reactions
Martirosyan, Karen S.; Zyskin, Maxim; Jenkins, Charles M.; (Yuki) Horie, Yasuyuki
2012-11-01
This paper reports the modeling of pressure waves from the explosive reaction of nano-thermites consisting of mixtures of nanosized aluminum and oxidizer granules. Such nanostructured thermites have higher energy density (up to 26 kJ/cm3) and can generate a transient pressure pulse four times larger than that from trinitrotoluene (TNT) based on volume equivalence. A plausible explanation for the high pressure generation is that the reaction times are much shorter than the time for a shock wave to propagate away from the reagents region so that all the reaction energy is dumped into the gaseous products almost instantaneously and thereby a strong shock wave is generated. The goal of the modeling is to characterize the gas dynamic behavior for thermite reactions in a cylindrical reaction chamber and to model the experimentally measured pressure histories. To simplify the details of the initial stage of the explosive reaction, it is assumed that the reaction generates a one dimensional shock wave into an air-filled cylinder and propagates down the tube in a self-similar mode. Experimental data for Al/Bi2O3 mixtures were used to validate the model with attention focused on the ratio of specific heats and the drag coefficient. Model predictions are in good agreement with the measured pressure histories.
Acoustic Pressure Waves in Vibrating 3-D Laminated Beam-Plate Enclosures
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.
Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water
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.
Zimei, Su; Wei, Xu; Hui, Yu; Fei, Du; Jicun, Wang; Kexin, Xu
2009-08-01
In this study the pulse wave characteristics were used as a new approach to measure the human blood pressure. Based the principle of pulse wave and theory of the elastic vascular, the authors analyzed the characteristic of the pulse waveforms and revealed the characteristics points which could be used to represent the blood pressure. In this investigation the relevant mathematical feature was used to identify the relationship between the blood pressure and pulse wave parameters in a more accurate way. It also provided an experimental basis to carry out continuing non-invasive blood pressure monitoring using the pulse wave method.
Pressure and wall heat transfer behind a hydrogen/azide detonation wave in narrow tubes
The reported study is concerned with the pressure evolution behind the detonation wave in tubes with an interior diameter in the range from 1 to 10 mm. Hydrogen azide in tubes with length-to-diameter ratios greater than 375 was detonated. The initial pressures were in the range from 1 to 20 Torr. The pressure behind the leading shock was measured with piezoelectrical transducers made of lead titanate and lead zirconate. It was found that the detonation velocity depends on wall heat losses. The wall heat flux observed behind the wave front was not in agreement with that calculated for constant flow parameters. In the diameter and pressure range considered, the wall heat flux varies strongly with tube diameter. This observation can be related to flow deviations regarding the Chapman-Jouguet parameters
Non-invasive measurement of local pulse pressure by pulse wave-based ultrasound manometry (PWUM)
Vappou, J.; Luo, J; Okajima, K.; Di Tullio, M; Konofagou, E E
2011-01-01
The central Blood Pressure (CBP) has been established as a relevant indicator of cardiovascular disease. Despite its significance, CBP remains particularly challenging to measure in standard clinical practice. The objective of this study is to introduce Pulse Wave-based Ultrasound Manometry (PWUM) as a simple-touse, non-invasive ultrasound-based method for quantitative measurement of the central pulse pressure. Arterial wall displacements are estimated using radiofrequency (RF) ultrasound sig...
Wilder, Michael C.; Reda, Daniel C.
2004-01-01
The NASA-Ames ballistic range provides a unique capability for aerothermodynamic testing of configurations in hypersonic, real-gas, free-flight environments. The facility can closely simulate conditions at any point along practically any trajectory of interest experienced by a spacecraft entering an atmosphere. Sub-scale models of blunt atmospheric entry vehicles are accelerated by a two-stage light-gas gun to speeds as high as 20 times the speed of sound to fly ballistic trajectories through an 24 m long vacuum-rated test section. The test-section pressure (effective altitude), the launch velocity of the model (flight Mach number), and the test-section working gas (planetary atmosphere) are independently variable. The model travels at hypersonic speeds through a quiescent test gas, creating a strong bow-shock wave and real-gas effects that closely match conditions achieved during actual atmospheric entry. The challenge with ballistic range experiments is to obtain quantitative surface measurements from a model traveling at hypersonic speeds. The models are relatively small (less than 3.8 cm in diameter), which limits the spatial resolution possible with surface mounted sensors. Furthermore, since the model is in flight, surface-mounted sensors require some form of on-board telemetry, which must survive the massive acceleration loads experienced during launch (up to 500,000 gravities). Finally, the model and any on-board instrumentation will be destroyed at the terminal wall of the range. For these reasons, optical measurement techniques are the most practical means of acquiring data. High-speed thermal imaging has been employed in the Ames ballistic range to measure global surface temperature distributions and to visualize the onset of transition to turbulent-flow on the forward regions of hypersonic blunt bodies. Both visible wavelength and infrared high-speed cameras are in use. The visible wavelength cameras are intensified CCD imagers capable of integration
Internal Ballistics of High Velocity Special Purpose Guns
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.
Gunshot wounds: A review of ballistics related to penetrating trauma
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.
Experimental study on pressure wave propagation through the open end of pipe
The steam generators of a double pool type liquid metal fast breeder reactor (LMFBR) are used in a large sodium pool which is formed between the primary vessel and the secondary vessel and accommodates the entire secondary heat transport system. Therefore, if there is a sodium-water reaction event in the steam generator, it becomes important to evaluate the pressure rises at the walls of the primary and secondary vessels as well as those at the other secondary components. An experimental study was performed, focusing on the propagation of the initial pressure spike of the-sodium-water reaction from the bottom end of the steam generator to the sodium pool. Pressure wave propagation from inside of a pipe to an open space through the pipe end was measured. Two kinds of pressure propagation media, water and air, ensured a wide range of experimental conditions. The experimental results revealed that the pressure attenuation at the open end of a pipe can be put in order using the concept of inertial length, and that the dimensionless inertial length, i.e., the inertial length divided by the half wave length of the pressure pulse, is proportional to the square of the dimensionless diameter. These results provide a prediction method for a pressure rise by the initial pressure spike in the secondary sodium pool of the Double Pool LMFBR
Internal wave pressure, velocity, and energy flux from density perturbations
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...
Mangiante, G; Dagradi, V; Radin, S; Carolo, F; Giarolli, M; Tenci, A; Merico, G; Tosi, D; Acerbi, A; Della Giacoma, G
1993-01-01
We have chosen to conceive of terminal ballistics as a violent and extremely rapid confrontation between two forms of resistance before the final state of rest is reached. This definition, which cannot help but don the admittedly loud and outlandish garb of physics, is the most promising for the purposes of biological interpretation. The main characters on this stage are two, but only one of these really plays the lead, namely the human target, which acts out the basic roles inherent in its physical make-up; the other, the bullet, remains a background figure, frozen in its walk-on part, and ready for the next performance. This modus operandi, which is no simplification, but rather an academic necessity, enables us to focus on images which stand out more clearly as a result of an intensive macroscopic spotlight which brings out the features of the individual phenomena, broken down into a succession of close-ups, and subtracts them from the cold physical nature of this or that form of inert matter, which here is merely an occasional, disagreeable witness, or even more, a standing from time to time for but one of the infinite facets of the biological composite being. Here, then, faced with a kind of exploded macrophotograph of a complex kaleidoscope, we see the animal universe, of which we capture so far the plasticity, the subdivisibility, the anisotropy and the cavitation. PMID:7923493
A theoretical study on the propagation of a pressure wave in a diphasic medium, when compared to the onset mechanism of pulmonary lesions in subjects exposed to strong shock waves, shows an increase in the incident overpressure at the interface level. Using hydrophones, intracorporal pressure was measured in pigs. The authors recorded the costal wall acceleration on the side directly exposed to the shock wave and calculated the displacement of the costal wall after a shock wave passed by. These experiments were conducted for shock waves in a free field, at an overpressure peak level ranging from 26 kFPa to 380 kPa and for a first positive phase lasting 2 ms. Sensors placed in an intracorporal position detected no increase of the overpressure level for any value of the incident pressure. A comparison of the costal wall displacement, measured experimentally, relative to the theoretical displacement of the entire animal mass indicates that the largest relative displacement of the costal wall could be the origin of the pulmonary lesions found. 5 refs., 13 figs
A MW-class mercury target for the spallation neutron source is subjected to the pressure waves and cavitation erosion induced by high-intense pulsed-proton beam bombardment. Helium-gas microbubbles injection into mercury is one of the effective techniques to suppress the pressure waves. The microbubble injection technique was developed. The selection test of bubble generators indicated that the bubble generator utilizing swirl flow of liquid (swirl-type bubble-generator) will be suitable from the viewpoint of the produced bubble size. However, when single swirl-type bubble-generator was used in flowing mercury, swirl flow of mercury remains at downstream of the generator. The remaining swirl flow causes the coalescence of bubbles which results in ineffective suppression of pressure waves. To solve this concern, a multi-swirl type bubble-generator, which consists of several single swirl-type bubble-generators arraying in the plane perpendicular to mercury flow direction, was invented. The multi-swirl type bubble-generator was tested in mercury and the geometry was optimized to generate small bubble with low flow resistance based on the test results. It is estimated to generate the microbubbles of 65 μm in radius under the operational condition of the Japanese Spallation Neutron Source mercury target, which is the sufficient size to suppress the pressure waves. (author)
George, Atanasiu; Chiru, Anghel
2014-06-01
This paper aims on comparison between a turbocharged engine and a pressure wave charged engine. The comparison was accomplished using the engine simulation software AVL Boost, version 2010. The grahps were extracted using AVL Impress, version 2010. The performance increase is limited by the mechanical side of the simulated engine.
3D problem of pressure wave propagation in the tube with inconstant
Pochylý, F.; Habán, V.; Foldyna, Josef; Sitek, Libor
Vienna: Viena University of Technology , 2007, s. 1-4. ISBN N. [International Congress on Ultrasonics. Vienna (AT), 09.04.2007-12.04.2007] R&D Projects: GA ČR GA101/07/1451 Institutional research plan: CEZ:AV0Z30860518 Keywords : pressure pulsations * wave equation * second viscosity Subject RIV: JQ - Machines ; Tools
Relations between diabetes, blood pressure and aortic pulse wave velocity in haemodialysis patients
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...
The most common method of clinical measurement of arterial blood pressure is by means of the cuff sphygmomanometer. This instrument has provided fundamental quantitative information on arterial pressure in individual subjects and in populations and facilitated estimation of cardiovascular risk related to levels of blood pressure obtained from the brachial cuff. Although the measurement is taken in a peripheral limb, the values are generally assumed to reflect the pressure throughout the arterial tree in large conduit arteries. Since the arterial pressure pulse becomes modified as it travels away from the heart towards the periphery, this is generally true for mean and diastolic pressure, but not for systolic pressure, and so pulse pressure. The relationship between central and peripheral pulse pressure depends on propagation characteristics of arteries. Hence, while the sphygmomanometer gives values of two single points on the pressure wave (systolic and diastolic pressure), there is additional information that can be obtained from the time-varying pulse waveform that enables an improved quantification of the systolic load on the heart and other central organs. This topical review will assess techniques of pressure measurement that relate to the use of the cuff sphygmomanometer and to the non-invasive registration and analysis of the peripheral and central arterial pressure waveform. Improved assessment of cardiovascular function in relation to treatment and management of high blood pressure will result from future developments in the indirect measurement of arterial blood pressure that involve the conventional cuff sphygmomanometer with the addition of information derived from the peripheral arterial pulse. (topical review)
Avolio, Alberto P; Butlin, Mark; Walsh, Andrew
2010-01-01
The most common method of clinical measurement of arterial blood pressure is by means of the cuff sphygmomanometer. This instrument has provided fundamental quantitative information on arterial pressure in individual subjects and in populations and facilitated estimation of cardiovascular risk related to levels of blood pressure obtained from the brachial cuff. Although the measurement is taken in a peripheral limb, the values are generally assumed to reflect the pressure throughout the arterial tree in large conduit arteries. Since the arterial pressure pulse becomes modified as it travels away from the heart towards the periphery, this is generally true for mean and diastolic pressure, but not for systolic pressure, and so pulse pressure. The relationship between central and peripheral pulse pressure depends on propagation characteristics of arteries. Hence, while the sphygmomanometer gives values of two single points on the pressure wave (systolic and diastolic pressure), there is additional information that can be obtained from the time-varying pulse waveform that enables an improved quantification of the systolic load on the heart and other central organs. This topical review will assess techniques of pressure measurement that relate to the use of the cuff sphygmomanometer and to the non-invasive registration and analysis of the peripheral and central arterial pressure waveform. Improved assessment of cardiovascular function in relation to treatment and management of high blood pressure will result from future developments in the indirect measurement of arterial blood pressure that involve the conventional cuff sphygmomanometer with the addition of information derived from the peripheral arterial pulse. PMID:19940350
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.
Modeling wave-induced pore pressure and effective stress in a granular seabed
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.
Effect of the dynamic pressure on the shock wave structure in a rarefied polyatomic gas
Taniguchi, Shigeru, E-mail: taniguchi@stat.nitech.ac.jp; Sugiyama, Masaru, E-mail: sugiyama@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Arima, Takashi, E-mail: tks@stat.nitech.ac.jp [Center for Social Contribution and Collaboration, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Ruggeri, Tommaso, E-mail: tommaso.ruggeri@unibo.it [Department of Mathematics and Research Center of Applied Mathematics (CIRAM), University of Bologna, Bologna (Italy)
2014-01-15
We study the shock wave structure in a rarefied polyatomic gas based on a simplified model of extended thermodynamics in which the dissipation is due only to the dynamic pressure. In this case the differential system is very simple because it is a variant of Euler system with a new scalar equation for the dynamic pressure [T. Arima, S. Taniguchi, T. Ruggeri, and M. Sugiyama, Phys. Lett. A 376, 2799–2803 (2012)]. It is shown that this theory is able to describe the three types of the shock wave structure observed in experiments: the nearly symmetric shock wave structure (Type A, small Mach number), the asymmetric structure (Type B, moderate Mach number), and the structure composed of thin and thick layers (Type C, large Mach number)
Effects of Shelves on Amplification of Long Waves Generated by Atmospheric Pressure Differences
Duha Metin, Ayse; Cevdet Yalciner, Ahmet; Ozyurt Tarakcıoglu, Gulizar; Zaytsev, Andrey
2016-04-01
Meteotsunami is a type of long period ocean wave generated by different types of meteorological disturbances such as atmospheric gravity waves, spatial and temporal pressure distributions and squall lines. The main idea behind the occurrence of this type of long wave is that low atmospheric pressure leads to static water level rise in a part of the marine area and high atmospheric pressure leads to static water level drop in another zone. Then, it causes deformation of the water level throughout the entire sea area. The relation between the pressure difference and change of water level from normal position (η =0.99Δ P where η is the water level change (cm) according to the pressure difference from normal pressure Δ P) can be used to determine the sea level deformation. The relation represents that 1 hPa decrease in air pressure causes 1 cm rise in mean sea level. Due to the spatial and temporal changes of atmospheric pressure, the respective small amplitude long waves propagate along the entire marine area. This type of tsunami-like waves can propagate through long distances and can also be amplified due to resonant effects in the enclosed basins, offshore shelves, and nearshore/offshore coastal morphology. Therefore, it can result in considerable amplifications and causes unexpected effects in some coastal regions. This study is mainly focused on understanding of amplification of long waves generated by atmospheric pressure differences when they encounter the offshore shelves while it is propagating towards to the shore. The problem is investigated by numerically solving nonlinear shallow water equations by using regular shaped basins with different depth and shelf characteristics. In all cases, the rectangular shape large basin is triggered by spatial and temporal distributions of atmospheric pressure. The water depth and shelf formation is changed for different cases. Initially, a deep flat bottom basin is used in simulations and the reference data of water
Ballistic propagation of turbulence front in tokamak edge plasmas
The flux-driven nonlinear simulation of resistive ballooning mode turbulence with tokamak edge geometry is performed to study the non-steady component in the edge turbulence. The large-scale and dynamical events in transport are investigated in a situation where the mean flow is suppressed. Two types of dynamics are observed. One is the radial propagation of the pulse of pressure gradient, the other is the appearance/disappearance of radially elongated global structure of turbulent heat flux. The ballistic propagation is observed in the pulse of pressure gradient, which is associated with the front of turbulent heat flux. We focus on this ballistic propagation phenomenon. Both of the bump of pressure gradient and the front of heat flux propagate inward and outward direction. It is confirmed that the strong fluctuation propagates with the pulse front. It is observed that the number of pulses going outward is close to those going inward. This ballistic phenomenon does not contradict to the turbulence spreading theory. Statistical characteristics of the ballistic propagation of pulses are evaluated and compared with scaling laws which is given by the turbulence spreading theory. It is found that they give qualitatively good agreement. (paper)
Continuous blood pressure monitoring during exercise using pulse wave transit time measurement.
Lass, J; Meigas, K; Karai, D; Kattai, R; Kaik, J; Rossmann, M
2004-01-01
This paper gives an overview of a research, which is focused on the development of the convenient device for continuous non-invasive monitoring of arterial blood pressure. The blood pressure estimation method is based on a presumption that there is a singular relationship between the pulse wave propagation time in arterial system and blood pressure. The parameter used in this study is pulse wave transit time (PWTT). The measurement of PWTT involves the registration of two time markers, one of which is based on ECG R peak detection and another on the detection of pulse wave in peripheral arteries. The reliability of beat to beat systolic blood pressure calculation during physical exercise was the main focus for the current paper. Sixty-one subjects (healthy and hypertensive) were studied with the bicycle exercise test. As a result of current study it is shown that with the correct personal calibration it is possible to estimate the beat to beat systolic arterial blood pressure during the exercise with comparable accuracy to conventional noninvasive methods. PMID:17272172
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.
Pressure transducer used for measuring close-in shock waves of nuclear explosions in the atmosphere
This paper introduces a variable reluctance pressure transducer. It has been successfully used for the measurement of close-in shock waves of nuclear explosions in the atmosphere. This transducer's highest pressure range is 100kg/cm2 and its response rise time for all ranges is lms. It uses a specially made oil-filled pressure which allows the transducer to be able to realize underground installation. In this way, it can endure the intense nuclear radiation of nuclear explosions without losing its fast speed response characteristics. This transducer has undergone a series of environmental tests and dynamic standardizations. Therefore, it was used to measure the complete waveform of shock wave overpressure in areas near the fire ball of nuclear explosions. This paper lists the test data of a group of nuclear explosion tests
Comparison of actinide production in traveling wave and pressurized water reactors
The geopolitical problems associated with civilian nuclear energy production arise in part from the accumulation of transuranics in spent nuclear fuel. A traveling wave reactor is a type of breed-burn reactor that could, if feasible, reduce the overall production of transuranics. In one possible configuration, a cylinder of natural or depleted uranium would be subjected to a fast neutron flux at one end. The neutrons would transmute the uranium, producing plutonium and higher actinides. Under the right conditions, the reactor could become critical, at which point a self-stabilizing fission wave would form and propagate down the length of the reactor cylinder. The neutrons from the fission wave would burn the fissile nuclides and transmute uranium ahead of the wave to produce additional fuel. Fission waves in uranium are driven largely by the production and fission of 239Pu. Simulations have shown that the fuel burnup can reach values greater than 400 MWd/kgIHM, before fission products poison the reaction. In this work we compare the production of plutonium and minor actinides produced in a fission wave to that of a UOX fueled light water reactor, both on an energy normalized basis. The nuclide concentrations in the spent traveling wave reactor fuel are computed using a one-group diffusion model and are verified using Monte Carlo simulations. In the case of the pressurized water reactor, a multi-group collision probability model is used to generate the nuclide quantities. We find that the traveling wave reactor produces about 0.187 g/MWd/kgIHM of transuranics compared to 0.413 g/MWd/kgIHM for a pressurized water reactor running fuel enriched to 4.95 % and burned to 50 MWd/kgIHM. (authors)
Comparison of actinide production in traveling wave and pressurized water reactors
Osborne, A.G.; Smith, T.A.; Deinert, M.R. [Department of Mechanical Engineering, University of Texas at Austin, Austin, TX (United States)
2013-07-01
The geopolitical problems associated with civilian nuclear energy production arise in part from the accumulation of transuranics in spent nuclear fuel. A traveling wave reactor is a type of breed-burn reactor that could, if feasible, reduce the overall production of transuranics. In one possible configuration, a cylinder of natural or depleted uranium would be subjected to a fast neutron flux at one end. The neutrons would transmute the uranium, producing plutonium and higher actinides. Under the right conditions, the reactor could become critical, at which point a self-stabilizing fission wave would form and propagate down the length of the reactor cylinder. The neutrons from the fission wave would burn the fissile nuclides and transmute uranium ahead of the wave to produce additional fuel. Fission waves in uranium are driven largely by the production and fission of {sup 239}Pu. Simulations have shown that the fuel burnup can reach values greater than 400 MWd/kgIHM, before fission products poison the reaction. In this work we compare the production of plutonium and minor actinides produced in a fission wave to that of a UOX fueled light water reactor, both on an energy normalized basis. The nuclide concentrations in the spent traveling wave reactor fuel are computed using a one-group diffusion model and are verified using Monte Carlo simulations. In the case of the pressurized water reactor, a multi-group collision probability model is used to generate the nuclide quantities. We find that the traveling wave reactor produces about 0.187 g/MWd/kgIHM of transuranics compared to 0.413 g/MWd/kgIHM for a pressurized water reactor running fuel enriched to 4.95 % and burned to 50 MWd/kgIHM. (authors)
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
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...
Low-frequency pressure wave propagation in liquid-filled, flexible tubes. (A)
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 com......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......) 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...... the model and are compared with results of experimental pressure wave propagation in the liquid-filled, flexible tube. A good agreement between experimental data and theoretical predictions is found....
Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave
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.
The dynamics of pressure and form drag on a sloping headland: Internal waves versus eddies
Warner, Sally J.; MacCready, Parker
2014-03-01
Topographically generated eddies and internal waves have traditionally been studied separately even though bathymetry that creates both phenomena is abundant in coastal regions. Here a numerical model is used to understand the dynamics of eddy and wave generation as tidal currents flow past Three Tree Point, a 1 km long, 200 m deep, sloping headland in Puget Sound, WA. Bottom pressure anomalies due to vertical perturbations of the sea surface and isopycnals are used to calculate form drag in different regions of the topography to assess the relative importance of eddies versus internal waves. In regions where internal waves dominate, sea surface and isopycnal perturbations tend to work together to create drag, whereas in regions dominated by eddies, sea surface, and isopycnal perturbations tend to counteract each other. Both phenomena are found to produce similar amounts of form drag even though the bottom pressure anomalies from the eddy have much larger magnitudes than those created by the internal waves. Topography like Three Tree Point is common in high latitude, coastal regions, and therefore the findings here have implications for understanding how coastal topography removes energy from tidal currents.
Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells
Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.
2014-01-01
The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction.
Pressure wave measurements from thermal cook-off of an HMX based high explosive
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.
Pressure Wave Measurements from Thermal Cook-off of an HMX Based Explosive
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.
Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501
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.
Loads on structures inside reactor pressure vessels due to loca - decompression waves
A theoretical model is described to calculate forces and moments onto core barrels, guide tubes of control rods, grid plates etc. inside the reactor pressure vessel due to decompression waves propagating with sonic velocity from the fracture during loss-of-coolant accidents in light water reactors. Simplicity of the model, short computer times and sufficient accuracy were the boundary conditions for the development. Therefore, no fluid dynamic coupling with the structure is considered. The main equations of the model are given and explained. The results of parametric studies as well as comparison to decompression wave experiments and calculations with coupling are presented. (orig.)
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
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.
Central blood pressure assessment using 24-hour brachial pulse wave analysis
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
Combined ultrasonic elastic wave velocity and microtomography measurements at high pressures
Combined ultrasonic and microtomographic measurements were conducted for simultaneous determination of elastic property and density of noncrystalline materials at high pressures. A Paris-Edinburgh anvil cell was placed in a rotation apparatus, which enabled us to take a series of x-ray radiography images under pressure over a 180 deg. angle range and construct accurately the three-dimensional sample volume using microtomography. In addition, ultrasonic elastic wave velocity measurements were carried out simultaneously using the pulse reflection method with a 10 deg. Y-cut LiNbO3 transducer attached to the end of the lower anvil. Combined ultrasonic and microtomographic measurements were carried out for SiO2 glass up to 2.6 GPa and room temperature. A decrease in elastic wave velocities of the SiO2 glass was observed with increasing pressure, in agreement with previous studies. The simultaneous measurements on elastic wave velocities and density allowed us to derive bulk (Ks) and shear (G) moduli as a function of pressure. Ks and G of the SiO2 glass also decreased with increasing pressure. The negative pressure dependence of Ks is stronger than that of G, and as a result the value of Ks became similar to G at 2.0-2.6 GPa. There is no reason why we cannot apply this new technique to high temperatures as well. Hence the results demonstrate that the combined ultrasonic and microtomography technique is a powerful tool to derive advanced (accurate) P-V-Ks-G-(T) equations of state for noncrystalline materials.
Cavitation inception by the backscattering of pressure waves from a bubble interface
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.
CMOS-compatible ruggedized high-temperature Lamb wave pressure sensor
This paper describes the development of a novel ruggedized high-temperature pressure sensor operating in lateral field exited (LFE) Lamb wave mode. The comb-like structure electrodes on top of aluminum nitride (AlN) were used to generate the wave. A membrane was fabricated on SOI wafer with a 10 µm thick device layer. The sensor chip was mounted on a pressure test package and pressure was applied to the backside of the membrane, with a range of 20–100 psi. The temperature coefficient of frequency (TCF) was experimentally measured in the temperature range of −50 °C to 300 °C. By using the modified Butterworth–van Dyke model, coupling coefficients and quality factor were extracted. Temperature-dependent Young's modulus of composite structure was determined using resonance frequency and sensor interdigital transducer (IDT) wavelength which is mainly dominated by an AlN layer. Absolute sensor phase noise was measured at resonance to estimate the sensor pressure and temperature sensitivity. This paper demonstrates an AlN-based pressure sensor which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications. (paper)
CMOS-compatible ruggedized high-temperature Lamb wave pressure sensor
Kropelnicki, P.; Muckensturm, K.-M.; Mu, X. J.; Randles, A. B.; Cai, H.; Ang, W. C.; Tsai, J. M.; Vogt, H.
2013-08-01
This paper describes the development of a novel ruggedized high-temperature pressure sensor operating in lateral field exited (LFE) Lamb wave mode. The comb-like structure electrodes on top of aluminum nitride (AlN) were used to generate the wave. A membrane was fabricated on SOI wafer with a 10 µm thick device layer. The sensor chip was mounted on a pressure test package and pressure was applied to the backside of the membrane, with a range of 20-100 psi. The temperature coefficient of frequency (TCF) was experimentally measured in the temperature range of -50 °C to 300 °C. By using the modified Butterworth-van Dyke model, coupling coefficients and quality factor were extracted. Temperature-dependent Young's modulus of composite structure was determined using resonance frequency and sensor interdigital transducer (IDT) wavelength which is mainly dominated by an AlN layer. Absolute sensor phase noise was measured at resonance to estimate the sensor pressure and temperature sensitivity. This paper demonstrates an AlN-based pressure sensor which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications.
On the pressure wave problem in liquid metal targets for pulsed spallation neutron sources
A liquid metal target for a pulsed spallation source was modelled on the computer to investigate the effect of the high instantaneous power deposition (60 KJ in 1 μs) on the pressure in the liquid and the resulting stress on the container. It was found that for the short pulse duration the resulting stress would be likely to exceed the allowable design stress for steels of the HT-9 type with low nickel content. Adding a small volume fraction of gas bubbles might be a way to suppress almost completely the generation of pressure waves. (author) 12 figs., 5 refs
A Treatise on Quantum Ballistic Motion and its Applications
Bracher, Christian
2007-01-01
The motion of a charged quantum particle in a homogeneous electric field is one of the rare examples of an analytically solvable problem in quantum mechanics in realistic three-dimensional configuration space. In the thesis, an exact expression for the propagator (energy Green function) describing this quantum ballistic motion for particles of some fixed energy emitted by a pointlike isotropic source is derived. Also, it is shown how to extend this theory to higher partial waves, thereby esta...
From ballistic to Brownian vortex motion in complex oscillatory media
Davidsen, Jörn; Erichsen, Ronaldo; Kapral, Raymond; Chaté, Hugues
2004-01-01
We show that the breaking of the rotation symmetry of spiral waves in two-dimensional complex (period-doubled or chaotic) oscillatory media by synchronization defect lines (SDL) is accompanied by an intrinsic drift of the pattern. Single vortex motion changes from ballistic flights at a well-defined angle from the SDL to Brownian-like diffusion when the turbulent character of the medium increases. It gives rise, in non-turbulent multi-spiral regimes, to a novel ``vortex liquid''.
Pressure broadening measurement of submillimeter-wave lines of O3
Yamada, M. M.; Amano, T.
2005-10-01
The pressure broadening coefficients and their temperature dependences for two submillimeter-wave transitions of ozone, one being monitored with Odin and the other to be monitored with JEM/SMILES and EOS-MLS, have been determined by using a BWO based submillimeter-wave spectrometer. The measurements have also been extended to one of the symmetric isotopic species, 16O18O16O. The isotopic species is observed in natural abundance and as a consequence the temperature dependence is not determined due to weak signal intensity. The pressure broadening parameters are determined with better than 1% accuracy, while the temperature dependence exponents are obtained within 1.5 3% accuracy for the normal species transitions.
Pressure broadening measurement of submillimeter-wave lines of O{sub 3}
Yamada, M.M. [Institute for Astrophysics and Planetary Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512 (Japan); Amano, T. [Institute for Astrophysics and Planetary Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512 (Japan)]. E-mail: amano@mx.ibaraki.ac.jp
2005-10-01
The pressure broadening coefficients and their temperature dependences for two submillimeter-wave transitions of ozone, one being monitored with Odin and the other to be monitored with JEM/SMILES and EOS-MLS, have been determined by using a BWO based submillimeter-wave spectrometer. The measurements have also been extended to one of the symmetric isotopic species, {sup 16}O{sup 18}O{sup 16}O. The isotopic species is observed in natural abundance and as a consequence the temperature dependence is not determined due to weak signal intensity. The pressure broadening parameters are determined with better than 1% accuracy, while the temperature dependence exponents are obtained within 1.5-3% accuracy for the normal species transitions.
Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.
2016-07-01
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.
Mohiuddin, Mohammad W; Rihani, Ryan J; Laine, Glen A; Quick, Christopher M
2012-07-01
The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (C(tot)) and increases in total peripheral resistance (R(tot)) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because increases in pulse wave velocity (c(ph)) make the reflected pressure wave arrive earlier, augmenting systolic pressure. It has recently been shown, however, that increases in c(ph) do not have a commensurate effect on the timing of the reflected wave. We therefore used a validated, large-scale, human arterial system model that includes realistic pulse wave transmission to determine whether increases in c(ph) cause increased PP with age. First, we made the realistic arterial system model age dependent by altering cardiac output (CO), R(tot), C(tot), and c(ph) to mimic the reported changes in these parameters from age 30 to 70. Then, c(ph) was theoretically maintained constant, while C(tot), R(tot), and CO were altered. The predicted increase in PP with age was similar to the observed increase in PP. In a complementary approach, C(tot), R(tot), and CO were theoretically maintained constant, and c(ph) was increased. The predicted increase in PP was negligible. We found that increases in c(ph) have a limited effect on the timing of the reflected wave but cause the system to degenerate into a windkessel. Changes in PP can therefore be attributed to a decrease in C(tot). PMID:22561301
Interactions of Delta Shock Waves for Zero-Pressure Gas Dynamics with Energy Conservation Law
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.
M.U.R. Naidu
2012-01-01
Full Text Available Objective: The aim of the present study was to validate and compare novel methods to determine aortic blood pressure non-invasively based on Oscillometric Pulse Wave Velocity (PWV measurement using four limb-cuff pressure waveforms and two lead Electrocardiogram (ECG with a validated tonometric pulse wave analysis system in patients. Materials and Methods: After receiving the consent, in 49 patients with hypertension, coronary artery disease, diabetes mellitus, PWV, and central blood pressures were recorded in a randomised manner using both the oscillometric and tonometric devices. All recordings were performed 10 minutes after the patient lying comfortably in a noise-free temperature-controlled room. The test was performed between 09 am and 10 am after overnight fast. A minimum of three measurements were performed by the same skilled and trained operator. From the raw data obtained with two devices, software calculated the final vascular parameters. Results: A total of 49 patients (8 women and 41 men, of mean age 40.5 years (range: 19-81 years participated in the present study. After transforming the brachial pressures into aortic pressures, the correlation coefficient between the Aortic Systolic Pressure (ASP values obtained with two methods was 0.9796 (P<0.0001. The mean difference between ASP with two methods was 0.3 mm Hg. Similarly, Aortic Diastolic Pressure (ADP values obtained with two methods also correlated significantly with correlation coefficient of 0.9769 (P<0.0001. The mean difference of ADP was 0.2 mm Hg. In case of Aortic Pulse Pressure (APP, the mean difference was 0.1 mm Hg. All parameters of central aortic pressures obtained with two methods correlated significantly. Conclusion: The new method of transforming the Carotid Femoral PWV (cfPWV and brachial blood pressure values into aortic blood pressure values seems to be reasonably good. The significant correlation between the values obtained by tonometric device and
Ballistics examination of air rifle
Grzegorz Bogiel
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.
Ballistics examination of air rifle
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.
Drift wave excitation in the THETA-pinch high pressure plasma
Excitation of low-frequency (LF) drift waves has been experimentally investigated in a high-pressure plasma in a gas discharge of the direct THETA-pinch type. The electrodeless inductive gas discharge is produced in an alundum tube of 150 cm length and 6.5 cm internal diameter filled with hydrogen at the pressure of (1-20).10-3 mm Hg. The discharge magnetic field (MF) has been investigated by a system of five magnetic probes both oriented along the radius and the length of the discharge chamber. The longitudinal temperature of electrons reaches 4 keV at the 6 kV voltage on the coil. Successive development of two types of instability has been observed: HF ''starting'' and LF ones. The LF oscillations observed have been identified as drift waves in a system with large β. The amplitude of the MF oscillations for the given instability may be compared with the value of the main MF, and the transverse wave lengths for these oscillations are of the order of the plasma filament radius. The longitudinal wave lengths are comparable with the magnetic system length
Isothermal self-similar blast wave theory of supernova remnants driven by relativistic gas pressure
The spherically symmetric, self-similar flow behind a blast wave from a point explosion in a medium whose density varies with distance as rsup(-ω) is investigated with the assumption that the flow is both isothermal and contains a relativistic component of pressure. A self-similar solution is shown to exist only if both the blast wave speed, usub(s), and the local sound speed, w, are constant. If Ω [equivalent to ω(1-w2/c2)] lies in 1 >Ω>0, there exists a critical point in the radial distance-flow velocity plane. To be physically acceptable, the solution must pass through the origin and through the critical point and then through to the blast front; solution branches between these points exist, although a proper connection at the critical point has not been demonstrated. It is concluded that isothermal self-similar blast waves do not provide a valid model for a supernova remnant driven by a relativistic gas pressure. Since the validity of the adiabatic blast wave models has elsewhere been shown to be questionable, it is doubtful whether the self-similar property can be involved at all in the case of supernova remnants. This raises serious questions of interpretation of quantities deduced for supernova remnants on the basis of the use of self-similar models. (Auth.)
Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.
Wang, Junjie; Wang, Meng; Xu, Jian; Peng, Li; Yang, Minghong; Xia, Minghe; Jiang, Desheng
2014-10-01
This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55 MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767 μs. Finally, three aspects that need further study for practical use are pointed out. PMID:25322237
Evaluation of sloshing wave crest impact pressure acting on a fixed roof cylindrical tank
This report describes the applicability of a newly developed computer code SLOSH-3D on estimating of sloshing wave crest impact pressure acting on a fixed roof of cylindrical tank. Based on the computed results, slosh-induced pressure loads and distribution on the tank roof is presented. A large shaking table test conducted on the E-Defense shaking table by a joint study group, composed of some electric companies, has been analyzed. In the shaking table test, partially water-filled cylindrical tank (diameter: 3m, height: 3m, water depth: 2.3m or 1.9m) with a flat fixed roof was subjected to a sinusoidal excitation at the first sloshing resonant frequency. The computer code well simulated the observed waveform with a spiky rising large pressure at the time of liquid impact on the tank wall, including appearance of negative pressures in the post impact period, with sufficient accuracy. As for the liquid impact zone of the tank roof including the water splash phenomena, the numerical computations indicated good agreement with the observed results. Furthermore, the numerical computations provided the total pressure load and pressure distribution on the tank wall at an instant of time when maximum pressure peak occurs. Consequently, the computer code SLOSH-3D was capable of predicting the complex nonlinear sloshing behavior with the collision of the liquid surface against the thank roof with an acceptable level of accuracy. (author)
In situ measurements of impact-induced pressure waves in sandstone targets
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.
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.
Non-invasive measurement of local pulse pressure by pulse wave-based ultrasound manometry (PWUM)
Central blood pressure (CBP) has been established as a relevant indicator of cardiovascular disease. Despite its significance, CBP remains particularly challenging to measure in standard clinical practice. The objective of this study is to introduce pulse wave-based ultrasound manometry (PWUM) as a simple-to-use, non-invasive ultrasound-based method for quantitative measurement of the central pulse pressure. Arterial wall displacements are estimated using radiofrequency ultrasound signals acquired at high frame rates and the pulse pressure waveform is estimated using both the distension waveform and the local pulse wave velocity. The method was tested on the abdominal aorta of 11 healthy subjects (age 35.7±16 y.o.). PWUM pulse pressure measurements were compared to those obtained by radial applanation tonometry using a commercial system. The average intra-subject variability of the pulse pressure amplitude was found to be equal to 4.2 mmHg, demonstrating good reproducibility of the method. Excellent correlation was found between the waveforms obtained by PWUM and those obtained by tonometry in all subjects (0.94 < r < 0.98). A significant bias of 4.7 mmHg was found between PWUM and tonometry. PWUM is a highly translational method that can be easily integrated in clinical ultrasound imaging systems. It provides an estimate of the pulse pressure waveform at the imaged location, and may offer therefore the possibility to estimate the pulse pressure at different arterial sites. Future developments include the validation of the method against invasive estimates on patients, as well as its application to other large arteries
Pressure Wave Measurements During Thermal Explosion of HMX-Based High Explosives
Forbes, J W; Garcia, F; Tarver, C M; Urtiew, P A; Greenwood, D W; Vandersall, K S
2002-06-27
Five different experiments on thermal heating of explosive materials have been performed. Three experiments thermally exploded PBX 9501 (HMX/Estane/BDNPA-F; 9512.512.5 wt %) donor charges while two others thermally exploded LX-04 (HMX/Viton A; 85/15 wt %). These donor charges were encased in 304 stainless steel. The transmitted two-dimensional pressure waves were measured by gauges in acceptor cylinders of Teflon, PBX 9501, or LX-04 that were in contact with the donors' steel case. A fifth experiment measured the pressure in an acceptor charge of PBX 9501 that had a 100 mm stand-off from the top of the steel case of the thermally cooked off PBX 9501 donor charge. Reactive flow hydrodynamic modeling using a rapid deflagration velocity of approximately 500 m/s was able to reproduce the pressure gauge records for both the in contact and stand off experiments that used PBX 9501 donors and acceptors.
Balakalyani, G.; Saravanan, S.; Jagadeesh, G.
Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.
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.
High pressure generation by laser driven shock waves: application to equation of state measurement
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 μm. 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.)
Vanneste, D.; Troch, P.
2012-01-01
The spatial distribution of the wave-induced pore pressure height in the core of a conventional rubble-mound breakwater is studied in this work. Use is made of existing theoretical and experimental knowledge to establish a calculation model for the pressure distribution on the front core slope and the attenuation of pore pressures within the breakwater core. The new model formulae are derived empirically and calibrated by means of a non-linear regression analysis of pore pressure measurements...
Qingmin Hou; Liang Ren; Wenling Jiao; Pinghua Zou; Gangbing Song
2013-01-01
Methods that more quickly locate leakages in natural gas pipelines are urgently required. In this paper, an improved negative pressure wave method based on FBG based strain sensors and wavelet analysis is proposed. This method takes into account the variation in the negative pressure wave propagation velocity and the gas velocity variation, uses the traditional leak location formula, and employs Compound Simpson and Dichotomy Searching for solving this formula. In addition, a FBG based strain...
Cavitation inception by the backscattering of pressure waves from a bubble interface
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.
Attenuation of wave-induced groundwater pressure in shallow water. Part 2. Theory
Stanisław R. Massel
2005-09-01
Full Text Available In this Part 2 of the paper (Part 1 was published by Massel et al. 2004 an exact close-form solution for the pore-water pressure component and velocity circulation pattern induced by surface waves is developed. This comprehensive theoretical model, based on Biot's theory, takes into account soil deformations, volume change and pore-water flow. The calculations indicate that for the stiffness ratio G/E'w ≥ 100, the vertical distribution of the pore pressure becomes very close to the Moshagen & Tørum (1975 approach, when the soil is rigid and the fluid is incompressible. The theoretical results of the paper have been compared with the experimental data collected during the laboratory experiment in the Large Wave Channel in Hannover (see Massel et al. 2004 and showed very good agreement. The apparent bulk modulus of pore water was not determined in the experiment but was estimated from the best fit of the experimental pore-water pressure with the theoretical one. In the paper only a horizontal bottom is considered and the case of an undulating bottom will be dealt with in another paper.
PHERMEX applications to study high-pressure flow and detonation waves
Pulsed High-Energy Radiographic Machine Emitting X Rays (PHERMEX), has been used as a diagnostic tool to make quantitative measurements from radiographs of inert materials under dynamic high-pressure conditions and of explosives during the detonation process. In some experiments, radiography is the best method (compared to high-speed optical cameras and contactor pins) to study complicated hydrodynamic flow occurring in a dynamic experiment. To demonstrate the versatility and uniqueness of PHERMEX and the radiographic method, several experiments on inert solids having high and low atomic numbers will be discussed with some particulars. This includes the observation of the 11.0-GPa-pressure phase transition for antimony and the accompanying two-shock structure and the off-Hugoniot data for lead using regular reflection. Also, by careful design of a radiographic experiment, the Hugoniot state behind a shock front can be completely and precisely specified. Aluminum is an example of a material studies in this manner. PHERMEX is useful in studying some detonation properties of explosives. As an illustration, the discussion will include radiographic results of divergence characteristics of a detonation wave in sensitive and insensitive explosives as it propagates past a corner and the effect of preshocking on the detonation process of insensitive explosives when the detonation wave interacts with a region that has been shock-compressed at a pressure too low to cause detonation
First hints of pressure waves in a helical extragalactic jet: S5~0836+710
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...
Qingmin Hou
2013-01-01
Full Text Available Methods that more quickly locate leakages in natural gas pipelines are urgently required. In this paper, an improved negative pressure wave method based on FBG based strain sensors and wavelet analysis is proposed. This method takes into account the variation in the negative pressure wave propagation velocity and the gas velocity variation, uses the traditional leak location formula, and employs Compound Simpson and Dichotomy Searching for solving this formula. In addition, a FBG based strain sensor instead of a traditional pressure sensor was developed for detecting the negative pressure wave signal produced by leakage. Unlike traditional sensors, FBG sensors can be installed anywhere along the pipeline, thus leading to high positioning accuracy through more frequent installment of the sensors. Finally, a wavelet transform method was employed to locate the pressure drop points within the FBG signals. Experiment results show good positioning accuracy for natural gas pipeline leakage, using this new method.
Constrained ballistics and geometrical optics
Epstein, Marcelo
2014-01-01
The problem of constant-speed ballistics is studied under the umbrella of non-linear non-holonomic constrained systems. The Newtonian approach is shown to be equivalent to the use of Chetaev's rule to incorporate the constraint within the initially unconstrained formulation. Although the resulting equations are not, in principle, obtained from a variational statement, it is shown that the trajectories coincide with those of geometrical optics in a medium with a suitably chosen refractive inde...
Optimal pressure-sensitive cuts for surface acoustic waves on langasite
无
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
On the ballistic response of comminuted ceramics
Recent results have strongly suggested that the ballistic-resistance of different comminuted ceramics is similar, independent of the original strength of the material. In particular, experimental work focused on the ballistic response of such materials has suggested that ballistic response is largely controlled by shattered material morphology. Consequently, it has been postulated that control of the nature of ceramic fragmentation should provide a potential route to optimise post-impact ballistic resistance. In particular, such an approach would open up a route to control in multi-hit capabilities. Here, ballistic tests into pre-formed 'fragmented-ceramic' analogues assembled from compacted alumina powders with two differing morphologies were conducted. Strong hints of a morphology-based contribution to ballistic resistance were apparent, although there was insufficient fidelity in the experimental data set to categorically identify the nature of this contribution.
The influence of ALN-Al gradient material gradient index on ballistic performance
Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.
The influence of ALN-Al gradient material gradient index on ballistic performance
Wang, Youcong; Liu, Qiwen; Li, Yao; Shen, Qiang
2013-03-01
Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.
Evaluation of mechanical losses in a linear motor pressure wave generator
Jacob, Subhash; Rangasamy, Karunanithi; Jonnalagadda, Kranthi Kumar; Chakkala, Damu; Achanur, Mallappa; Govindswamy, Jagadish; Gour, Abhay Singh
2012-06-01
A moving magnet linear motor compressor or pressure wave generator (PWG) of 2 cc swept volume with dual opposed piston configuration has been developed to operate miniature pulse tube coolers. Prelimnary experiments yielded only a no-load cold end temperature of 180 K. Auxiliary tests and the interpretation of detailed modeling of a PWG suggest that much of the PV power has been lost in the form of blow-by at piston seals due to large and non-optimum clearance seal gap between piston and cylinder. The results of experimental parameters simulated using Sage provide the optimum seal gap value for maximizing the delivered PV power.
Earth--Mars Transfers with Ballistic Capture
Topputo, Francesco; Belbruno, Edward
2014-01-01
We construct a new type of transfer from the Earth to Mars, which ends in ballistic capture. This results in a substantial savings in capture $\\Delta v$ from that of a classical Hohmann transfer under certain conditions. This is accomplished by first becoming captured at Mars, very distant from the planet, and then from there, following a ballistic capture transfer to a desired altitude within a ballistic capture set. This is achieved by manipulating the stable sets, or sets of initial condit...
Structural ballistic armour for transport aircraft
Horsfall, I; Austin, S J; Bishop, W.
2000-01-01
This paper describes the structural response of a current ceramic-faced composite armour system and a proposed structural armour system for aircraft use. The proposed structural ballistic armour system is shown to be capable of providing significant structural integrity even after ballistic impact whilst providing ballistic protection equivalent to an existing applique system. The addition of a carbon fibre reinforced plastic front panel to the existing ceramic faced composite armour system i...
Seismic attenuation: effects of interfacial impedance on wave-induced pressure diffusion
Qi, Qiaomu; Müller, Tobias M.; Rubino, J. Germán
2014-12-01
Seismic attenuation and dispersion in layered sedimentary structures are often interpreted in terms of the classical White model for wave-induced pressure diffusion across the layers. However, this interlayer flow is severely dependent on the properties of the interface separating two layers. This interface behaviour can be described by a pressure jump boundary condition involving a non-vanishing interfacial impedance. In this paper, we incorporate the interfacial impedance into the White model by solving a boundary value problem in the framework of quasi-static poroelasticity. We show that the White model predictions for attenuation and dispersion substantially change. These changes can be attributed to petrophysically plausible scenarios such as imperfect hydraulic contacts or the presence of capillarity.
Studies on an improved indigenous pressure wave generator and its testing with a pulse tube cooler
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.
High Definition Oscillometry: Non-invasive Blood Pressure Measurement and Pulse Wave Analysis.
Egner, Beate
2015-01-01
Non-invasive monitoring of blood pressure has become increasingly important in research. High-Definition Oscillometry (HDO) delivers not only accurate, reproducible and thus reliable blood pressure but also visualises the pulse waves on screen. This allows for on-screen feedback in real time on data validity but even more on additional parameters like systemic vascular resistance (SVR), stroke volume (SV), stroke volume variances (SVV), rhythm and dysrhythmia. Since complex information on drug effects are delivered within a short period of time, almost stress-free and visible in real time, it makes HDO a valuable technology in safety pharmacology and toxicology within a variety of fields like but not limited to cardiovascular, renal or metabolic research. PMID:26091643
Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao
2014-01-01
Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications. PMID:25316410
Simard, J. Marc; Pampori, Adam; Keledjian, Kaspar; Tosun, Cigdem; Schwartzbauer, Gary; Ivanova, Svetlana; Gerzanich, Volodymyr
2014-01-01
Traumatic brain injury (TBI) caused by an explosive blast (blast-TBI) is postulated to result, in part, from transvascular transmission to the brain of a hydrodynamic pulse (a.k.a., volumetric blood surge, ballistic pressure wave, hydrostatic shock, or hydraulic shock) induced in major intrathoracic blood vessels. This mechanism of blast-TBI has not been demonstrated directly. We tested the hypothesis that a blast wave impacting the thorax would induce a hydrodynamic pulse that would cause pa...
The Atucha II Nuclear Power Plant is being built in a riverside site located about 100 km north of the city of Buenos Aires. When completed it will become Argentina's third operating station. The Service Water Pump House of the 740 MW Natural Uranium NPP is supplied directly by the Parana de las Palmas River, which is a navigable waterway with heavy fluvial traffic that links the River Plate Estuary with ports along the Parana River, including Rosario, Argentina's third city. Although dolphins were built to protect the water intake structures from direct impact from ships or barges, an accidental escape of gas or flammable material outside the protected area that may result in an explosion with a subsequent pressure wave, could not be precluded. Thus, the water intake structures had to be designed against this event. In addition, concern with the margin of safety against foundation instability due to the overturning moment associated to the induced pressures, made an evaluation of the conditional probability of failure for this loading condition, desirable. The task placed still uncommon demands on the Project Engineers, who were required to provide estimates of the Pump House reliability. In the process, it became necessary to introduce assumptions concerning the unspecified variability of the loads which, according to current international practice, were defined in the form of 'deterministic' design criteria. It seems appropriate to underline these deficiencies in current standards, as well as in aspects of the dynamic of soils that are responsible for a quite large model uncertainty. On the basis of available information, it may be established that the probability of occurrence of a pressure wave at the site is less than 10-3 per year. Accordingly, the probability of failure of the foundation due to a pressure wave does not exceed 1.5 -8 per year, value that is considered admissible by current standards. The use of triangular probability density functions for
Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs
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.
Employing the reductive perturbation technique, Zakharov–Kuznetzov (ZK) equation is derived for dust acoustic (DA) solitary waves in a magnetized plasma which consists the effects of dust anisotropic pressure, arbitrary charged dust particles, Boltzmann distributed ions, and Kappa distributed superthermal electrons. The ZK solitary wave solution is obtained. Using the small-k expansion method, the stability analysis for DA solitary waves is also discussed. The effects of the dust pressure anisotropy and the electron superthermality on the basic characteristics of DA waves as well as on the three-dimensional instability criterion are highlighted. It is found that the DA solitary wave is rarefactive (compressive) for negative (positive) dust. In addition, the growth rate of instability increases rapidly as the superthermal spectral index of electrons increases with either positive or negative dust grains. A brief discussion for possible applications is included
Gas cloud explosions cause air pressure waves which propagate over the ground surface. The ground motion induced by these loads and their effect on structures are studied. The soil is modelled as a linear viscoelastic medium. A semianalytical method is used to compute the ground motion produced by a deflagration and by a detonation in a stiff and a soft layered soil. For a PWR reactor building subjected to the direct impact of an air pressure wave the additional effects of the ground waves on the motion of the building are studied. Whereas the vertical structural response is increased, the horizontal response decreases, when the effect of the ground waves is included. For the case studied the additional effect of the ground waves is small. (orig.)
Experimental determination of radiated internal wave power without pressure field data
We present a method to determine, using only velocity field data, the time-averaged energy flux (J) and total radiated power P for two-dimensional internal gravity waves. Both (J) and P are determined from expressions involving only a scalar function, the stream function ψ. 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 edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data
Beigelbeck, Roman; Antlinger, Hannes; Cerimovic, Samir; Clara, Stefan; Keplinger, Franz; Jakoby, Bernhard
2013-12-01
Increasing demands for online monitoring of liquids have not only resuted in many new devices relying on well-established sensing parameters like shear viscosity but also initiated research on alternative parameters. Recently, the longitudinal viscosity has been evaluated as a promising candidate because the devices arising enable the bulk of the liquid to be probed rather than a thin surface layer. We report on a multi-purpose sensor which allows simultaneous measurement of the sound velocity and longitudinal viscosity of liquids. The device embodiment features a cube-shaped chamber containing the sample liquid, where one boundary surface carries a flush-mounted PZT transducer. In operation, the transducer induces standing, resonant pressure waves in the liquid under test. We studied the influences of sound velocity and longitudinal viscosity on the generated pressure waves by means of the Navier-Stokes equation for adiabatic compressible liquids and exploited both parameters as the basic sensing mechanism. Furthermore, a three-port network model describing the interaction of the transducer and sample liquid was developed in order to be applied for extracting the parameters of interest from the raw measurement data. Finally, we demonstrate the device and method by carrying out and discussing test measurements on glycerol-water solutions.
DAPSY - a computer program for the pressure wave propagation in reactor cooling systems
The computer code DAPSY is developed to calculate pressure wave phenomena in the primary coolant system. For this purpose it is necessary to treat 3-dimensional single-phase and two-phase flow of water and steam. The technique used in DAPSY is the simulation of the real geometry by a pipe network with connected one-dimensional flow paths. The calculation of the unsteady one-dimensional flow is taken from the BLAST code. In this code pressure wave propagation and delayed attainment of thermal equilibrium is taken into consideration. Integration by the method of characteristics in a fixed grid, which is used in this code, is very convenient for the computation of boundary value problems, especially for critical state of flow. In order to determine the boundary conditions of each pipe, calculated by the one-dimensional code, subroutines were developed, which simulate several components of the primary system, e.g. strong cross-section variations with eventual critical flow, valves, pumps, dead ends of pipes, perhaps with a gas bulb, breaking points with critical mass-flow rate and eventual orifices, connection points of several pipes, free surfaces of water with transition to steam phase, and separators in which two-phase mixture is divided in steam and water flow. These components can be composed in any way so that a whole primary system is described. (orig.)
Study of Internal Ballistics of Hepta-Tubular Powders
M. C. Gupta
1959-04-01
Full Text Available In thin paper a solution of the system of equations in Internal Ballistics of a, conventional gun has been discussed for the hepta-tubular powder. The shot-start pressure is taken diffe- rent from zero and the covolume correction also is taken I. into amount and thus some of the results of Tavernierl who has taken zero shot-start preasure and has neglected the . covolume~omtion, have been generalised. It has been. found out that the maximum pressure in the case of hepta-tubular powders always occurs before the all-burnt position.
Quantum Computation with Ballistic Electrons
Ionicioiu, Radu; Amaratunga, Gehan; Udrea, Florin
2000-01-01
We describe a solid state implementation of a quantum computer using ballistic single electrons as flying qubits in 1D nanowires. We show how to implement all the steps required for universal quantum computation: preparation of the initial state, measurement of the final state and a universal set of quantum gates. An important advantage of this model is the fact that we do not need ultrafast optoelectronics for gate operations. We use cold programming (or pre-programming), i.e., the gates are...
Graham, John B., Jr.
1958-01-01
Heat-transfer and pressure measurements were obtained from a flight test of a 1/18-scale model of the Titan intercontinental ballistic missile up to a Mach number of 3.86 and Reynolds number per foot of 23.5 x 10(exp 6) and are compared with the data of two previously tested 1/18-scale models. Boundary-layer transition was observed on the nose of the model. Van Driest's theory predicted heat-transfer coefficients reasonably well for the fully laminar flow but predictions made by Van Driest's theory for turbulent flow were considerably higher than the measurements when the skin was being heated. Comparison with the flight test of two similar models shows fair repeatability of the measurements for fully laminar or turbulent flow.
Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Fujii, T.; Nagao, J.
2014-12-01
P-wave velocity is an important parameter to estimate gas hydrate saturation in sediments. In this study, the relationship between gas hydrate saturation and P-wave velocity have been analyzed using natural hydrate-bearing-sediments obtained in the Eastern Nankai Trough, Japan. The sediment samples were collected by the Hybrid Pressure Coring System developed by Japan Agency for Marine-Earth Science and Technology during June-July 2012, aboard the deep sea drilling vessel CHIKYU. P-wave velocity was measured on board by the Pressure Core Analysis and Transfer System developed by Geotek Ltd. The samples were maintained at a near in-situ pressure condition during coring and measurement. After the measurement, the samples were stored core storage chambers and transported to MHRC under pressure. The samples were manipulated and cut by the Pressure-core Non-destructive Analysis Tools or PNATs developed by MHRC. The cutting sections were determined on the basis of P-wave velocity and visual observations through an acrylic window equipped in the PNATs. The cut samples were depressurized to measure gas volume for saturation calculations. It was found that P-wave velocity correlates well with hydrate saturation and can be reproduced by the hydrate frame component model. Using pressure cores and pressure core analysis technology, nondestructive and near in-situ correlation between gas hydrate saturation and P-wave velocity can be obtained. This study was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.
Saint-Remy, Annie; Krzesinski, Jean-Marie
2010-01-01
The present study aimed to define reference values of central blood pressure (cBP) and Pulse Wave Velocity (PWV) together with 24H ABPM in healthy normotensive young adults before starring a follow-up of their CV profile modifications over time. Peer reviewed
Saint-Remy, Annie; Krzesinski, Jean-Marie
2010-01-01
The present study aimed to define reference values of central blood pressure (cBP) and Pulse Wave Velocity (PWV) together with 24H APPM in healththy normotensive young adults before starting a follow-up of their CV profile modifications over time. Peer reviewed
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.
Ballistic electron transport in mesoscopic samples
In the framework of this thesis, the electron transport in the ballistic regime has been studied. Ballistic means that the lateral sample dimensions are smaller than the mean free path of the electrons, i.e. the electrons can travel through the whole device without being scattered. This leads to transport characteristics that differ significantly from the diffusive regime which is realised in most experiments. Making use of samples with high mean free path, features of ballistic transport have been observed on samples with sizes up to 100 μm. The basic device used in ballistic electron transport is the point contact, from which a collimated beam of ballistic electrons can be injected. Such point contacts were realised with focused ion beam (FIB) implantation and the collimating properties were analysed using a two opposite point contact configuration. The typical angular width at half maximum is around 50 , which is comparable with that of point contacts defined by other methods. (orig.)
崔秀国; 艾慕阳; 姜保良; 霍连风; 张立新
2008-01-01
In order to research start-up pressure wave propagation mechanism and determine pressure wave speed in gelled crude oil pipelines accurately,experiment of Large-scale flow loop was carried out.In the experiment,start-up pressure wave speeds under various operation conditions were measured,and effects of correlative factors on pressure wave were analyzed.The experimental and theoretical analysis shows that thermal shrinkage and structural properties of gelled crude oils are key factors influencing on start-up pressure wave propagation.The quantitative analysis for these effects can be done by using volume expansion coefficient and structural property parameter of gelled crude oil.A new calculation model of pressure wave speed was developed on the basis of Large-scale flow loop experiment and theoretical analysis.
Li, Jianling; Mi, XiaoCheng; 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 p...
The transfer of atmospheric-pressure ionization waves via a metal wire
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
The transfer of atmospheric-pressure ionization waves via a metal wire
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.
Shen, X. C.; Zong, Q.-G.; Shi, Q. Q.; Tian, A. M.; Sun, W. J.; Wang, Y. F.; Zhou, X. Z.; Fu, S. Y.; Hartinger, M. D.; Angelopoulos, V.
2015-09-01
Ultralow frequency (ULF) waves play an important role in transferring energy by buffeting the magnetosphere with solar wind pressure impulses. The amplitudes of magnetospheric ULF waves, which are induced by solar wind dynamic pressure enhancements or shocks, are thought to damp in one half a wave cycle or an entire wave cycle. We report in situ observations of solar wind dynamic pressure impulse-induced magnetospheric ULF waves with increasing amplitudes. We found six ULF wave events induced by solar wind dynamic pressure enhancements with slow but clear wave amplitude increase. During three or four wave cycles, the amplitudes of ion velocities and electric field of these waves increased continuously by 1.3-4.4 times. Two significant events were selected to further study the characteristics of these ULF waves. We found that the wave amplitude growth is mainly contributed by the toroidal mode wave. Three possible mechanisms of causing the wave amplitude increase are discussed. First, solar wind dynamic pressure perturbations, which are observed in a duration of 20-30 min, might transfer energy to the magnetospheric ULF waves continually. Second, the wave amplitude increase in the radial electric field may be caused by superposition of two wave modes, a standing wave excited by the solar wind dynamic impulse and a propagating compressional wave directly induced by solar wind oscillations. When superposed, the two wave modes fit observations as does a calculation that superposes electric fields from two wave sources. Third, the normal of the solar wind discontinuity is at an angle to the Sun-Earth line. Thus, the discontinuity will affect the dayside magnetopause continuously for a long time.
Star-grain rocket motor - nonsteady internal ballistics
Loncaric, S.; Greatrix, D.R.; Fawaz, Z. [Ryerson University, Dept. of Aerospace Engineering, Toronto (Canada)
2004-01-01
The nonsteady internal ballistics of a star-grain solid-propellant rocket motor are investigated through a numerical simulation model that incorporates both the internal flow and surrounding structure. The effects of structural vibration on burning rate augmentation and wave development in nonsteady operation are demonstrated. The amount of damping plays a role in influencing the predicted axial combustion instability symptoms of the motor. The variation in oscillation frequencies about a given star grain section periphery, and along the grain with different levels of burn-back, also influences the means by which the local acceleration drives the combustion and flow behaviour. (authors)
Wang, C. J.; Guo, C. M.
2014-09-01
The two-dimensional, time-dependent and reactive Navier-Stokes equations were solved to obtain an insight into Mach reflection of gaseous detonation in a stoichiometric hydrogen-oxygen mixture diluted by 25 % argon. This mixture generates a mode-7 detonation wave under an initial pressure of 8.00 kPa. Chemical kinetics was simulated by an eight-species, forty-eight-reaction mechanism. It was found that a Mach reflection mode always occurs for a planar detonation wave or planar air shock wave sweeping over wedges with apex angles ranging from to . However, for cellular detonation waves, regular reflection always occurs first, which then transforms into Mach reflection. This phenomenon is more evident for detonations ignited under low initial pressure. Low initial pressure may lead to a curved wave front, that determines the reflection mode. The stochastic nature of boundary shape and transition distance, during deflagration-to-detonation transition, leads to relative disorder of detonation cell location and cell shape. Consequently, when a detonation wave hits the wedge apex, there appears a stochastic variation of triple point origin and variation of the angle between the triple point trajectory and the wedge surface. As the wedge apex angle increases, the distance between the triple point trajectory origin and the wedge apex increases, and the angle between the triple point trajectory and the wedge surface decreases exponentially.
Ballistic and non-ballistic gas flow through ultrathin nanopores
We show that ultrathin porous nanocrystalline silicon membranes exhibit gas permeance that is several orders of magnitude higher than other membranes. Using these membranes, gas flow obeying Knudsen diffusion has been studied in pores with lengths and diameters in the tens of nanometers regime. The components of the flow due to ballistic transport and transport after reflection from the pore walls were separated and quantified as a function of pore diameter. These results were obtained in pores made in silicon. We demonstrate that changing the pore interior to carbon leads to flow enhancement resulting from a change in the nature of molecule–pore wall interactions. This result confirms previously published flow enhancement results obtained in carbon nanotubes. (paper)
One-Dimensional Simulation of the Pressure Wave near the Exit of a High-Speed Train Tunnel
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.``
Design and Experiment for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine
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.
An algorithm for extracting intracranial pressure latency relative to electrocardiogram R wave
Intracranial pressure (ICP) latency is defined as the time interval between the peak of the QRS complex of the electrocardiogram (ECG) and the corresponding onset of intracranial pressure (ICP) pulse. Due to its inherent relationship with arterial pulse wave velocity, ICP latency may allow continuous monitoring of pathophysiological changes in the cerebrovasculature. The objective of the present work was to develop and validate a computerized algorithm for extracting ICP latency in a beat-by-beat fashion. The proposed ICP latency extraction algorithm exploits the mature technique of ECG QRS detection and includes a new adaptive peak detection methodology. The results were validated by comparing the performance of two human observers versus the algorithm in terms of locating the onset points of ICP pulses for 59 recordings extracted from 25 adult patients. The average ICP latency was 72.6 ± 19.5 ms (range 40.0–159.8). The ICP pulse detection algorithm demonstrated a baseline sensitivity of 0.97 and a positive predictivity of 0.88. No difference was found in the mean location errors from comparing the results obtained by the two observers and those from comparing the results from the algorithm to those from the two observers. Further investigation is needed to demonstrate the role of ICP latency in characterizing dynamic cerebral vascular pathophysiological changes in clinical states such as subarachnoid hemorrhage and traumatic brain injury
Optimization of pressure waveform, distribution and sequence in shock wave lithotripsy
Zhou, Yufeng
This work aims to improve shock wave lithotripsy (SWL) technology by increasing stone comminution efficiency while reducing simultaneously the propensity of tissue injury. First, the mechanism of vascular injury in SWL was investigated. Based on in vitro vessel phantom experiment and theoretical calculation, it was found that SWL-induced large intraluminal bubble expansion may constitute a primary mechanism for the rupture of capillaries and small blood vessels. However, when the large intraluminal bubble expansion is suppressed by inversion of the pressure waveform of the lithotripter shock wave (LSW), rupture of a 200-mum cellulose hollow fiber vessel phantom can be avoided. Based on these experimental observations and theoretical assessment of bubble dynamics using the Gilmore model an in situ pulse superposition technique was developed to reduce tissue injury without compromising stone comminution in SWL. A thin shell ellipsoidal reflector insert was fabricated to fit snugly with the original HM-3 reflector. Using the Hamilton model, the effects of reflector geometry on the pulse profile and sequence of the shock waves were evaluated qualitatively. Guided by this analysis, the design of the reflector insert had been refined to suppress the intraluminal bubble expansion, which was confirmed by high-speed imaging of bubble dynamics both in free field and inside a vessel phantom. The pulse pressure, beam size and stone comminution efficiency of the upgraded reflector were all found to be comparable to those of the original reflector. However, the greatest difference lies in the propensity for tissue injury. At the lithotripter focus, about 30 shocks are needed to cause a rupture of the vessel phantom using the original reflector, but no rupture can be produced after 200 shocks by the upgraded reflector. Overall, the upgraded reflector could significantly reduce the propensity of vessel rupture while maintaining satisfactory stone comminution. Second, to improve
Decoherence and disorder in quantum walks: From ballistic spread to localization
Schreiber, A; Potoček, V; Gábris, A; Jex, I; Silberhorn, Ch
2011-01-01
We investigate the impact of decoherence and static disorder on the dynamics of quantum particles moving in a periodic lattice. Our experiment relies on the photonic implementation of a one-dimensional quantum walk. The pure quantum evolution is characterized by a ballistic spread of a photon's wave packet along 28 steps. By applying controlled time-dependent operations we simulate three different environmental influences on the system, resulting in a fast ballistic spread, a diffusive classical walk and the first Anderson localization in a discrete quantum walk architecture.