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An Investigation of Shock Wave Propagation and Attenuation in the Lower Extremity Using Finite Element Analysis.

An Investigation of Shock Wave Propagation and Attenuation in the Lower Extremity Using Finite Element Analysis.

Across the ankle joint and along the length of the tibia, it was consistently found for both versions of the model that the peak accelerations were attenuated between each consecutive node (Tables 14 & 15). Although the ankle was responsible for a smaller proportion of shock attenuation than the distal tibia, this potentially could have been a function of the smaller distances between the most distal nodes. As previously discussed, version 3 exhibited the most biologically realistic peak acceleration values at the bone surface of the proximal tibia at 1 1 .3 g, which is similar to those reported previously in the literature (Chavet et al., 1997; Flynn et al., 2004; Holmes & Andrews, 2006; Lafortune et al., 1996 a, b; Schinkel-Ivy et al., 2010) (Table 16). With respect to the times to peak acceleration at each node, although the absolute TPA values may have been somewhat smaller than what were measured experimentally in the current study, the trend for each TPA value to be slightly delayed from that at the previous node indicated that the model reasonably represented the proximal movement of the shock wave across the ankle and along the tibia. Furthermore, previous work has reported that the peak accelerations at the distal tibia and head are removed in time by 10 ms (Derrick et al., 1998) and an average of 5.6 ms depending on impact velocity (Lafortune et al., 1996b). When these past results are taken into consideration, it appears that the small delays in time between adjacent nodes across the ankle and along the tibia may not be completely biologically
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Shock wave propagation in periodically layered composites

Shock wave propagation in periodically layered composites

IX 3 Experimental Systems for Shock Compression of Solids C-l 3.1 High Velocity Planar Impact Loading System C-l 3.2 Experimental Techniques: Diagnostic Systems C-3 3.2.l Arrival Time De[r]

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Shock Wave Propagation in Composites and Electro Thermomechanical Coupling of Ferroelectric Materials

Shock Wave Propagation in Composites and Electro Thermomechanical Coupling of Ferroelectric Materials

diagram of the impact problem for an impact speed of 75 ms −1 . Upon impact (t = 0), an elastic precursor travels into the target followed by a phase boundary marked by a large change in strain. It should be noted that the elastic wave is not sharp. This is because the computational method involved captures the elastic wave into the averaging process. To the contrary, the phase boundary is tracked by mesh updating and hence appears sharp in Figure 4.12b. The elastic precursor travels into the material, and reflects off the free edge of the target as a tensile wave. This tensile wave then interacts with the phase boundary. Figure 4.13a shows the current output through the external circuit for an impact speed of 75 ms −1 . The current output has an exponential profile with a steady current pulse, which is consistent with experimental observations. The profile is also consistent with the expression (4.73) derived using a simple one-dimensional uncoupled analysis in Section 4.3. The sharp decline corresponds to the time the reflected elastic precursor interacts with the phase boundary in Figure 4.12b. In real experiments, the sample used is ceramic, which gets damaged by the time the reflected wave comes back. As such, there is no current output after the sharp decline. Figure 4.13b shows the temperature map on the X − t diagram of the problem. Initially, both flyer and target are kept at room temperature of 298 K. It can be seen that the temperature rise associated with elastic waves is small, and can be barely seen in the flyer. The temperature increase across the phase boundary is around 5 − 10 K.
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Behavior   of a Pool Filled with Water and Loaded by an Internal Explosion

Behavior of a Pool Filled with Water and Loaded by an Internal Explosion

The pressure field value resulting from shock wave propagation is used to assess the behaviour of pool or tank walls when subjected to a rapid pressure change ver[r]

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Picosecond-resolution phase-sensitive imaging of transparent objects in a single shot

Picosecond-resolution phase-sensitive imaging of transparent objects in a single shot

With the growing interest in the optical imaging of ultrafast phenomena in transparent objects, from shock wave to neuronal action potentials, high contrast imaging at high frame rates has become desirable. While phase sensitivity provides the contrast, the frame rates and sequence depths are highly limited by the detectors. Here, we present phase-sensitive compressed ultrafast photography (pCUP) for single-shot real-time ultrafast imaging of transparent objects by combining the contrast of dark-field imaging with the speed and the sequence depth of CUP. By imaging the optical Kerr effect and shock wave propagation, we demonstrate that pCUP can image light- speed phase signals in a single shot with up to 350 frames captured at up to 1 trillion frames per second. We expect pCUP to be broadly used for a vast range of fundamental and applied sciences.
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Propagation of Exploding Uniform Strong Cylindrical Shock Wave in Condensed Medium (Water)

Propagation of Exploding Uniform Strong Cylindrical Shock Wave in Condensed Medium (Water)

The motion of converging cylindrical shock waves in a perfect gas with constant ratio specific heats has been studied by Stanyukovich (1960) using similar solutions. The propagation of spherically converging shock in various metals has been studied by Yadav and Singh (1982) by Whitham method. The shock wave propagation in water has been studied by Bhatnager et al.(1969), Singh(1972), Rango rao and Ramanna (1973), Singh et al.(1980), Singh and Shrivastava (1985) without taking gravity of earth. Viswakarma et al.(1988) considered earth’s gravitation and time dependant energy release. The analysis are completely analytical and are used for diverging shock only. The diverging shock propagation in uniform and non-uniform gas has been studied by Yadav (1992), Yadav and Tripathi (1995) considering the effect of overtaking disturbances.These results are in good agreement with experimental results.
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Considerations concerning the analysis of NPP structures subjected to blast loading

Considerations concerning the analysis of NPP structures subjected to blast loading

In this paper, uncertainties expected in the various stages of the process are examined in connection with the analysis of the air vent stack of a NPP presently under design. The spatial and temporal pressure distributions induced at the site by the blast were determined by means of a Finite Element model that simulates the shock wave propagation considering the topographical features of the site and the main structures of the NPP, as described in next section of the paper. The numerically determined pressures are compared with the IAEA NS-G-1.5 design recommendations and available experimental evidence, illustrating the expected variability of the prediction. In the following section, the loads induced by the shock wave in the air vent stack of the NPP as well as its dynamic response are determined employing several methods. On such basis, the validity of commonly accepted assumptions in the determination of the response of structures to blast loading is finally discussed.
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Propagation Regularity of Air Shock Wave in Turning Roadway

Propagation Regularity of Air Shock Wave in Turning Roadway

propagation of explosion shock waves in tunnels. Lu Hongqin et al. [6] compared the effects of straight wall arches, equal-span rectangular, square and circular tunnel cross-section shapes on the shock wave propagation characteristics in tunnels. Britan A et al. [7] studied the propagation attenuation law of air shock waves in complex network structures, and proposed the safety protection design and concept of underground space to deal with shock wave damage effects. Weiss [8] discussed the measures for the protection of underground facilities and personnel in explosion accidents through the study of the anti-blasting impact of underground structures and facilities. KANG Y et al [9]. studied the law of crack growth under the action of blast wave through experiments, and simulated the evolution law of explosive stress wave and explosion-induced crack growth with ANSYS/ ls-dyna. Results the relationship between the fracture zone and the natural fracture of rock containing natural fracture under the action of blast wave was obtained. LI Zhongxian et al [10]. used ls-dyna numerical simulation software to simulate the propagation law of blast wave in urban streets and its influence on surrounding buildings.
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This paper improves and perfects the theoretical model of jet penetrating a full-of-liquid single-cell structure. The theoretical results are in good agreement with the experimental results. The following findings were obtained: The theoretical model [6] of jet penetrating a full-of-liquid single structure is improved from the three aspects of shock wave propagation direction, propagation path, and reflection mode. The range of jet interference velocity is more accurate and the error is smaller in the theoretical model than the experiment results.

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Radiometric temperature analysis of the Hayabusa spacecraft re-entry

Radiometric temperature analysis of the Hayabusa spacecraft re-entry

designated World Heritage Sites, all relating to industrialisation. The success of modern Manchester is founded on scientific, industrial and social innovation; for historians, it is one of the world's key sites. Its early modern scientific connections date as far back as the 1600s, but it is from the late 1700s that Manchester establishes itself as a mercantile and industrial capital where sciences thrive. The key figures included John Dalton, the Quaker teacher who became famous for the atomic theory in chemistry; his friend William Henry (Henry's law); and his pupil James Prescott Joule, the brewer who established the mechanical equivalent of heat. The University of Manchester has recognised the importance of running international conferences as a way of promoting international cooperation in the dissemination of research and building collaborations between scholars across the world. The International Symposia on Shock Waves are the definitive meetings of the scientific community devoted to the study and use of the shock-wave phenomena, of all kinds. Started in 1957, they take place every two years, at places close to centres of activity in the field. After 1971 and 1999 in London, it was an honour for us to host the Symposium again in the United Kingdom.
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Multiplicity and structures for traveling wave solutions of the Kuramoto Sivashinsky equation

Multiplicity and structures for traveling wave solutions of the Kuramoto Sivashinsky equation

The rest of this paper is organized as follows. In Section 2, the problem is formulated and a far-field analysis is presented to elucidate the possibility of three classes of sta- tionary traveling wave solutions. Then, in Section 3, we present our numerical method and apply it to obtain traveling wave solutions of the KS equation. Finally, in Section 4, some comments and conclusion are given.

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Non-linear acoustic emissions from therapeutically driven contrast agent microbubbles

Non-linear acoustic emissions from therapeutically driven contrast agent microbubbles

Side-view imaging, with the FOV represented as a dashed rectangle in Figure 1a, was undertaken through a Monozoom 7 lens (Bausch & Lomb, Rochester, NY, USA) at 10 Mfps with a Shimadzu HPV-X2 camera (Shimadzu, Kyoto Japan) over a 25.6-ms duration from t = 125 ms, such that microbubble cavitation has evolved over »45 cycles of focused ultrasound driving. Illumina- tion was achieved with synchronous (to frame capture) 10-ns laser pulses (CAVILUX Smart, Cavitar, Tampere, Finland), coupled to a liquid light guide and collimating Fig. 1. (a) Schematic representation of the experimental configuration, depicting exposure of the capillary, orientated in the horizontal plane at 45˚ to the focused ultrasound, and the needle hydrophone in the emission collection position. Focused ultrasound propagates from left to right, and microbubble flow was from back right to front left, for this repre- sentation. The imaging axis and fields of view for the high-speed imaging are also represented (top view dotted, side view dashed). (b) Assessment of focused ultrasound propagation non-linearity, up to 4f 0 for the peak-negative pressure
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Impact of extracorporeal shock waves on the human skin with cellulite: A case study of an unique instance

Impact of extracorporeal shock waves on the human skin with cellulite: A case study of an unique instance

Affecting most post-adolescent women of all races, cellulite (gynoid lipodystrophy) – the dimpling of skin primarily on thighs and buttocks – can be considered as a normal macroscopic expression of the female skin (Müller and Nürnberger 1972; Pavicic et al 2006). It is uncommon in men. The majority of affected men also suffer androgen- defi ciency disorders (such as Klinefelter-syndrome, hypo-gonadism or cirrhosis; Baker et al 1976). While cellulite was the ideal type of women at the times of impressionism, today this “orange peel” aspect of the skin is severely unacceptable, such that it may induce embarrassment and psychosocial inhibition in those suffering its consequences. In itself cellulite is not potentially hazardous to health (Smith 2002). A few treatments ensured by some evidence-based support are available today (such as the mechanical therapy of folding-unfolding and suction called endermology, topically applied caffeine and retinol, and the recommendation of exercise and weight loss; Pavicic et al 2006). Medium-energy, high focused extracorporeal shock waves (ESW) applied locally to the skin with cellulite may be a potential noninvasive therapy approach. Recently low-energy defocused ESW treatment showed some evidence of remodeling of the collagen within the dermis (Angehrn et al 2007). Shock wave treatments are to be distinguished from high intensity ultrasound used in liposculpturing (Adamo et al 1997; Rohrich et al 2000).
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Wave propogation scattering due to defect on thin composite plates

Wave propogation scattering due to defect on thin composite plates

The engineering structures which based on laminated composites, have a high probability of unexpected damage development during services. The damage formations must be monitored from the beginning before it headed towards structural failure which could result in substantial damage. This lead to the necessity of Structural Health Monitoring (SHM) system to be installed during the construction of laminated composite structures. However, an understanding of damage area detection and damage characteristics is essential, before a SHM system can be integrated into the structures. This article presents the effects of propagating wave propagation through an existing damage on composite plates. Theoretically, a propagating wave that started from any source will vary when crossing an area with damage. This study shows a high frequency wave propagation (kHz range) show different reactions when passing through the damaged area, compared with the low frequency wave propagation. Results of the study will lead to good damage detection method, which utilizing the available vibration source; especially for the condition monitoring of thin laminated composite structures. Keywords: SHM; wave propagation; wavelet analysis; Gl/epoxy composites.
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A Shockwave Speed Estimation Method for Freeway Facilities Based on Archived Vehicle Probe Data.

A Shockwave Speed Estimation Method for Freeway Facilities Based on Archived Vehicle Probe Data.

In addition to the speeds of backward forming shock wave and forward recovery shock wave estimation in a speed index contour plot, the corresponding queue length can be estimated easily based on the proposed algorithm. The queue length refers to the maximum queue length in a congested regime during a peak period. In this thesis, two different methods were presented to estimate queue length after shockwave speed estimation. The first method is simply summing up the link lengths of all outputs, while in other method, the queue length was estimated in terms of speeds of backward forming shock wave and forward recovery shock wave as well as start time point of backward forming shock wave and end time point of forward recovery shock wave, as described below.
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EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

Aforementioned invasive methods are being gradually superseded by extracorporeal lithotripsy, available in Pakistan since August 1988, in which externally produced shock waves are focussed onto the stone. Repeated shocks act by alternately compressing the stone as the wave proceeds towards it and expanding it as the wave reflected from the far surface of the stone returns back as a tensile force. The shocks loosen up the texture of the stone, produce cracks in it and chip off minute particles from the surface..

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Influence of high latitude anomalies on tropical climate phenomena and global climate

Influence of high latitude anomalies on tropical climate phenomena and global climate

The first part of this thesis is a detailed examination of the “Tropical Atlantic Dipole” (TAD). Analysis of model data shows a dipole pattern in the SST, with strong cross-equatorial asymmetry in the surface mixed layer. Below the mixed layer the pattern becomes symmetric, and Kelvin and Rossby wave like adjustment can be seen to occur. However, the timeseries is not sufficiently long to provide confidence in resolving the power spectrum, and as such the results are inconclusive. The complexity of the model makes it difficult to identify the mechanism(s) which are responsible for driving the dipole. An idealised basin model is used to examine high latitude anomalies which create equatorward propagating coastal Kelvin waves as a possible driving mechanism for the TAD. The results show that coastal Kelvin wave propagation can quickly transmit a signal from the high latitude anomaly to the equator, and equatorial Kelvin and Rossby wave propagation can quickly influence the entire tropical ocean. This suggests that forcing of the TAD may come from higher latitudes, although it is still not fully understood how a symmetric sub-surface signal can become asymmetric at the surface. Restoring surface boundary conditions limit the response of the model, restricting the formation of a TAD. A similar experiment, using an idealised coupled model configuration is suggested, but not possible in the time available.
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Electromagnetic Wave Propagation into Fresh Water

Electromagnetic Wave Propagation into Fresh Water

Wireless communications from air to fresh water are studied here. Our analysis relies on plane wave propagation mod- els. Specifically, the transmission loss and propagation loss of RF waves penetrating into fresh water are calculated for various propagation depths. Even though RF wireless communications are not well suited for seawater due to its high attenuation, our paper illustrates that RF communications from air to fresh water are possible. Finally, this work de- rives the optimum frequencies, which provide minimum attenuation and maximum propagation depth, for RF commu- nications from air to fresh water.
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Influence of tidal sand wave fields on wind wave propagation

Influence of tidal sand wave fields on wind wave propagation

Modelling the true behaviour of wind-generated surface gravity waves (i.e. wind waves) is rather difficult due to the combined effects of several physical processes. In order to mathematically express the behaviour of wind waves, assumptions and simplifications are made to formulate the latter. The Mild-Slope Equation, which is the governing model equation, assumes linear harmonic waves, an inviscid, incompressible fluid, irrotational flow but moreover a slight variation of water depth over the distance of a wind wave length, i.e. a mild-sloping bathymetry. Beside these assumptions, boundary conditions are imposed in the model which require a priori knowledge about the angle of the inci- dence of the wind wave on these boundaries. In this model, these angles are estimated to be the same as the angle of the predefined incident, monochromatic wind wave at the incoming boundary. Errors in the expression of these boundary conditions might be reduced by for example iterative updating of these boundary conditions. All in all, the model is able to output the complex valued amplitudes, which should be interpret carefully due to the aforementioned assumptions.
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LASL Shock Hugoniot Data pdf

LASL Shock Hugoniot Data pdf

Dick, “Shock Wave Compression of Benzene, Carbon Disulfide, Carbon Tetrachloride, and Liquid Nitrogen,” Los Alamos Scientific Laboratory report LA-3915 1968.. Dick, “Shock Wave Compressi[r]

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