High-speed measurement of firearm primer blast waves

OpenAIRE

Courtney, Michael; Daviscourt, Joshua; Eng, Jonathan; Courtney, Amy

2012-01-01

This article describes a method and results for direct high-speed measurements of firearm primer blast waves employing a high-speed pressure transducer located at the muzzle to record the blast pressure wave produced by primer ignition. Key findings are: 1) Most of the lead styphnate based primer models tested show 5.2-11.3% standard deviation in the magnitudes of their peak pressure. 2) In contrast, lead-free diazodinitrophenol (DDNP) based primers had standard deviations of the peak blast p...

The tank's dynamic response under nuclear explosion blast wave

International Nuclear Information System (INIS)

Xu Mei; Wang Lianghou; Li Xiaotian; Yu Suyuan; Zhang Zhengming; Wan Li

2005-01-01

To weapons and equipment, blast wave is the primary destructive factor. In this paper, taken the real model-59 tank as an example, we try to transform the damage estimation problem into computing a fluid structure interaction problem with finite element method. The response of tank under nuclear explosion blast wave is computed with the general-coupling algorithm. Also, the dynamical interaction of blast wave and tank is reflected in real time. The deformation of each part of the tank is worked out and the result corresponds to the real-measured data. (authors)

Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

Energy Technology Data Exchange (ETDEWEB)

Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

2013-12-15

Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

Computational modeling of blast wave interaction with a human body and assessment of traumatic brain injury

Science.gov (United States)

Tan, X. G.; Przekwas, A. J.; Gupta, R. K.

2017-11-01

The modeling of human body biomechanics resulting from blast exposure poses great challenges because of the complex geometry and the substantial material heterogeneity. We developed a detailed human body finite element model representing both the geometry and the materials realistically. The model includes the detailed head (face, skull, brain and spinal cord), the neck, the skeleton, air cavities (lungs) and the tissues. Hence, it can be used to properly model the stress wave propagation in the human body subjected to blast loading. The blast loading on the human was generated from a simulated C4 explosion. We used the highly scalable solvers in the multi-physics code CoBi for both the blast simulation and the human body biomechanics. The meshes generated for these simulations are of good quality so that relatively large time-step sizes can be used without resorting to artificial time scaling treatments. The coupled gas dynamics and biomechanics solutions were validated against the shock tube test data. The human body models were used to conduct parametric simulations to find the biomechanical response and the brain injury mechanism due to blasts impacting the human body. Under the same blast loading condition, we showed the importance of inclusion of the whole body.

The use of computer blast simulations to improve blast quality

International Nuclear Information System (INIS)

Favreau, R.F.; Kuzyk, G.W.; Babulic, P.J.; Tienkamp, N.J.

1989-01-01

Atomic Energy of Canada Limited is constructing an Underground Research Laboratory (URL) as part of a comprehensive program to evaluate the concept of nuclear fuel waste disposal deep in crystalline rock formations. Careful blasting methods have been used to minimize damage to the excavation surfaces. Good wall quality is desirable in any excavation. In excavations required for nuclear waste disposal, the objective will be to minimize blast-induced fractures which may complicate the sealing requirements necessary to control subsequent movement of groundwater around a sealed disposal vault. The construction of the URL has provided an opportunity for the development of controlled blasting methods, especially for drilling accuracy and optimization of explosive loads in the perimeter and cushion holes. The work has been assisted by the use of blast simulations with the mathematical model Blaspa. This paper reviews the results of a recent project to develop a controlled method of full-face blasting, and compares the observed field results with the results of a blast simulator called Blaspa. Good agreement is found between the two, and the Blaspa results indicate quantitatively how the blasting may induce damage in the final excavation surface. In particular, the rock in the final wall may be stressed more severely by the cushion holes than by the perimeter holes. Bootleg of the rock between the perimeter and cushion rows occurs when the burst-out velocity imparted to it by the explosive loads in the perimeter holes is inadequate. In practice, these findings indicate that quantitative rock stress and rock burst-out velocity criteria can be established to minimize wall damage and bootleg. Thus, blast simulations become an efficient way to design controlled blasting and to optimize quality of the excavation surface

Numerical simulation of the fluid-structure interaction between air blast waves and soil structure

Science.gov (United States)

Umar, S.; Risby, M. S.; Albert, A. Luthfi; Norazman, M.; Ariffin, I.; Alias, Y. Muhamad

2014-03-01

Normally, an explosion threat on free field especially from high explosives is very dangerous due to the ground shocks generated that have high impulsive load. Nowadays, explosion threats do not only occur in the battlefield, but also in industries and urban areas. In industries such as oil and gas, explosion threats may occur on logistic transportation, maintenance, production, and distribution pipeline that are located underground to supply crude oil. Therefore, the appropriate blast resistances are a priority requirement that can be obtained through an assessment on the structural response, material strength and impact pattern of material due to ground shock. A highly impulsive load from ground shocks is a dynamic load due to its loading time which is faster than ground response time. Of late, almost all blast studies consider and analyze the ground shock in the fluid-structure interaction (FSI) because of its influence on the propagation and interaction of ground shock. Furthermore, analysis in the FSI integrates action of ground shock and reaction of ground on calculations of velocity, pressure and force. Therefore, this integration of the FSI has the capability to deliver the ground shock analysis on simulation to be closer to experimental investigation results. In this study, the FSI was implemented on AUTODYN computer code by using Euler-Godunov and the arbitrary Lagrangian-Eulerian (ALE). Euler-Godunov has the capability to deliver a structural computation on a 3D analysis, while ALE delivers an arbitrary calculation that is appropriate for a FSI analysis. In addition, ALE scheme delivers fine approach on little deformation analysis with an arbitrary motion, while the Euler-Godunov scheme delivers fine approach on a large deformation analysis. An integrated scheme based on Euler-Godunov and the arbitrary Lagrangian-Eulerian allows us to analyze the blast propagation waves and structural interaction simultaneously.

Study of Perturbations on High Mach Number Blast Waves in Various Gasses

Science.gov (United States)

Edens, A.; Adams, R.; Rambo, P.; Shores, J.; Smith, I.; Atherton, B.; Ditmire, T.

2006-10-01

We have performed a series of experiments examining the properties of high Mach number blast waves. Experiments were conducted on the Z-Beamlet^1 laser at Sandia National Laboratories. We created blast waves in the laboratory by using 10 J- 1000 J laser pulses to illuminate millimeter scale solid targets immersed in gas. Our experiments studied the validity of theories forwarded by Vishniac and Ryu^2-4 to explain the dynamics of perturbations on astrophysical blast waves. These experiments consisted of an examination of the evolution of perturbations of known primary mode number induced on the surface of blast waves by means of regularly spaced wire arrays. The temporal evolution of the amplitude of the induced perturbations relative to the mean radius of the blast wave was fit to a power law in time. Measurements were taken for a number of different mode numbers and background gasses and the results show qualitative agreement with previously published theories for the hydrodynamics of thin shell blast wave. The results for perturbations on nitrogen gas have been recently published^5. .^1 P. K. Rambo, I. C. Smith, J. L. Porter, et al., Applied Optics 44, 2421 (2005). ^2 D. Ryu and E. T. Vishniac, Astrophysical Journal 313, 820 (1987). ^3 D. Ryu and E. T. Vishniac, Astrophysical Journal 368, 411 (1991). ^4 E. T. Vishniac, Astrophysical Journal 274, 152 (1983). ^5 A. D. Edens, T. Ditmire, J. F. Hansen, et al., Physical Review Letters 95 (2005).

Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology

Science.gov (United States)

Chen, Yun; Huang, Wei; Constantini, Shlomi

2012-01-01

A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

Modeling and simulations of radiative blast wave driven Rayleigh-Taylor instability experiments

Science.gov (United States)

Shimony, Assaf; Huntington, Channing M.; Trantham, Matthew; Malamud, Guy; Elbaz, Yonatan; Kuranz, Carolyn C.; Drake, R. Paul; Shvarts, Dov

2017-10-01

Recent experiments at the National Ignition Facility measured the growth of Rayleigh-Taylor RT instabilities driven by radiative blast waves, relevant to astrophysics and other HEDP systems. We constructed a new Buoyancy-Drag (BD) model, which accounts for the ablation effect on both bubble and spike. This ablation effect is accounted for by using the potential flow model ]Oron et al PoP 1998], adding another term to the classical BD formalism: βDuA / u , where β the Takabe constant, D the drag term, uA the ablation velocity and uthe instability growth velocity. The model results are compared with the results of experiments and 2D simulations using the CRASH code, with nominal radiation or reduced foam opacity (by a factor of 1000). The ablation constant of the model, βb / s, for the bubble and for the spike fronts, are calibrated using the results of the radiative shock experiments. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207, and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Numerical simulation of muzzle blast

NARCIS (Netherlands)

Tyler-Street, M.

2014-01-01

Structural design methods for naval ships include environmental, operational and military load cases. One of the operational loads acting on a typical naval vessel is the muzzle blast from a gun. Simulating the muzzle blast load acting on a ship structure with CFD and ALE methods leads to large

The use of computer blast simulations to improve blast quality

International Nuclear Information System (INIS)

Favreau, R.F.; Kuzzyk, G.W.; Babulic, P.J.; Morin, R.A.; Tienkamp, N.J.

1987-01-01

An underground research laboratory (URL) has been constructed as part of a comprehensive program to evaluate the concept of nuclear fuel waste disposal in deep crystalline rock formations. Careful blasting methods have been used to minimize damage to the excavation surfaces. This paper reviews the results of the program to develop controlled blasting for the full-face method, comparing the field observed results achieved with the simulated theoretical results. The simulated results indicate how the blasting may damage the excavation surface. Results suggest that the rock around the final wall is stressed more severely by the cushion holes than by the perimeter holes and that bootleg of the rock between the perimeter and cushion rows occurs when the burst-out velocity imparted to it by the explosive loads in the perimeter holes is inadequate

Computational Study of Thrust Generation from Laser-Driven Blast Wave

International Nuclear Information System (INIS)

Ohnishi, Naofumi; Ogino, Yousuke

2008-01-01

We have performed axisymmetric simulations in order to investigate the thrust generation resulting from the interference between the projectile and the blast wave produced by a pulsed laser. The results obtained by our numerical code well agree for the pressure history and the momentum coupling coefficient with the experimental data. In such analysis, it is found that the approximate impulse estimated only by the pressure history at the projectile base is difficult to predict the actual one. Since the shock wave rapidly attenuates in low fill pressure, and the interaction with the projectile almost finishes in the shroud, a high momentum coupling coefficient can be achieved unlike the case of high fill pressure in which the projectile experiences the subsequent negative thrust

A study on impulsive sound attenuation for a high-pressure blast flow field

International Nuclear Information System (INIS)

Kang, Kuk Jeong; Ko, Sung Ho; Lee, Dong Soo

2008-01-01

The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flow field; these characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical solver for analyzing the high pressure blast flow field is developed in this study. From numerical simulations, wave dynamic processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle blasts) are simulated and discussed. The pressure variation of the blast flow field is analyzed to evaluate the effect of a silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful in understanding blast wave and in designing silencers

A study on impulsive sound attenuation for a high-pressure blast flow field

Energy Technology Data Exchange (ETDEWEB)

Kang, Kuk Jeong [Agency for Defence Development, Daejeon (Korea, Republic of); Ko, Sung Ho; Lee, Dong Soo [Chungnam National University, Daejeon (Korea, Republic of)

2008-01-15

The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flow field; these characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical solver for analyzing the high pressure blast flow field is developed in this study. From numerical simulations, wave dynamic processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle blasts) are simulated and discussed. The pressure variation of the blast flow field is analyzed to evaluate the effect of a silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful in understanding blast wave and in designing silencers

Spike morphology in blast-wave-driven instability experiments

International Nuclear Information System (INIS)

Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.; Fryxell, B.; Budde, A.; Hansen, J. F.; Miles, A. R.; Plewa, T.; Hearn, N.; Knauer, J.

2010-01-01

The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh-Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He-H interface during the explosion phase of a supernova. The experimental target is a 150 μm thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 μm and a wavelength of 71 μm. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh-Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetration observed in the experiments. The amount of mass reaching the shock front is analyzed and potential causes for the spike morphology and the spikes reaching the shock are discussed. One such hypothesis is that these phenomena may be caused by magnetic pressure, generated by an azimuthal magnetic field produced by the plasma dynamics.

Full-scale testing of leakage of blast waves inside a partially vented room exposed to external air blast loading

Science.gov (United States)

Codina, R.; Ambrosini, D.

2018-03-01

For the last few decades, the effects of blast loading on structures have been studied by many researchers around the world. Explosions can be caused by events such as industrial accidents, military conflicts or terrorist attacks. Urban centers have been prone to various threats including car bombs, suicide attacks, and improvised explosive devices. Partially vented constructions subjected to external blast loading represent an important topic in protective engineering. The assessment of blast survivability inside structures and the development of design provisions with respect to internal elements require the study of the propagation and leakage of blast waves inside buildings. In this paper, full-scale tests are performed to study the effects of the leakage of blast waves inside a partially vented room that is subjected to different external blast loadings. The results obtained may be useful for proving the validity of different methods of calculation, both empirical and numerical. Moreover, the experimental results are compared with those computed using the empirical curves of the US Defense report/manual UFC 3-340. Finally, results of the dynamic response of the front masonry wall are presented in terms of accelerations and an iso-damage diagram.

Nineteen-Foot Diameter Explosively Driven Blast Simulator; TOPICAL

International Nuclear Information System (INIS)

VIGIL, MANUEL G.

2001-01-01

This report describes the 19-foot diameter blast tunnel at Sandia National Laboratories. The blast tunnel configuration consists of a 6 foot diameter by 200 foot long shock tube, a 6 foot diameter to 19 foot diameter conical expansion section that is 40 feet long, and a 19 foot diameter test section that is 65 feet long. Therefore, the total blast tunnel length is 305 feet. The development of this 19-foot diameter blast tunnel is presented. The small scale research test results using 4 inch by 8 inch diameter and 2 foot by 6 foot diameter shock tube facilities are included. Analytically predicted parameters are compared to experimentally measured blast tunnel parameters in this report. The blast tunnel parameters include distance, time, static, overpressure, stagnation pressure, dynamic pressure, reflected pressure, shock Mach number, flow Mach number, shock velocity, flow velocity, impulse, flow duration, etc. Shadowgraphs of the shock wave are included for the three different size blast tunnels

CHALLENGING SOME CONTEMPORARY VIEWS OF CORONAL MASS EJECTIONS. I. THE CASE FOR BLAST WAVES

International Nuclear Information System (INIS)

Howard, T. A.; Pizzo, V. J.

2016-01-01

Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced the “traditional” view that CMEs were blast waves driven by solar flares. While the flux rope CME narrative is supported by a vast quantity of measurements made over five decades, it does not adequately describe every observation of what have been termed CME-related phenomena. In this paper we present evidence that some large-scale coronal eruptions, particularly those associated with EIT waves, exhibit characteristics that are more consistent with a blast wave originating from a localized region (such as a flare site) rather than a large-scale structure driven by an intrinsic flux rope. We present detailed examples of CMEs that are suspected blast waves and flux ropes, and show that of our small sample of 22 EIT-wave-related CMEs, 91% involve a blast wave as at least part of the eruption, and 50% are probably blast waves exclusively. We conclude with a description of possible signatures to look for in determining the difference between the two types of CMEs and with a discussion on modeling efforts to explore this possibility.

CHALLENGING SOME CONTEMPORARY VIEWS OF CORONAL MASS EJECTIONS. I. THE CASE FOR BLAST WAVES

Energy Technology Data Exchange (ETDEWEB)

Howard, T. A. [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Pizzo, V. J., E-mail: howard@boulder.swri.edu [NOAA Space Weather Prediction Center, Boulder, CO (United States)

2016-06-20

Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced the “traditional” view that CMEs were blast waves driven by solar flares. While the flux rope CME narrative is supported by a vast quantity of measurements made over five decades, it does not adequately describe every observation of what have been termed CME-related phenomena. In this paper we present evidence that some large-scale coronal eruptions, particularly those associated with EIT waves, exhibit characteristics that are more consistent with a blast wave originating from a localized region (such as a flare site) rather than a large-scale structure driven by an intrinsic flux rope. We present detailed examples of CMEs that are suspected blast waves and flux ropes, and show that of our small sample of 22 EIT-wave-related CMEs, 91% involve a blast wave as at least part of the eruption, and 50% are probably blast waves exclusively. We conclude with a description of possible signatures to look for in determining the difference between the two types of CMEs and with a discussion on modeling efforts to explore this possibility.

Investigations of primary blast-induced traumatic brain injury

Science.gov (United States)

Sawyer, T. W.; Josey, T.; Wang, Y.; Villanueva, M.; Ritzel, D. V.; Nelson, P.; Lee, J. J.

2018-01-01

The development of an advanced blast simulator (ABS) has enabled the reproducible generation of single-pulse shock waves that simulate free-field blast with high fidelity. Studies with rodents in the ABS demonstrated the necessity of head restraint during head-only exposures. When the head was not restrained, violent global head motion was induced by pressures that would not produce similar movement of a target the size and mass of a human head. This scaling artefact produced changes in brain function that were reminiscent of traumatic brain injury (TBI) due to impact-acceleration effects. Restraint of the rodent head eliminated these, but still produced subtle changes in brain biochemistry, showing that blast-induced pressure waves do cause brain deficits. Further experiments were carried out with rat brain cell aggregate cultures that enabled the conduct of studies without the gross movement encountered when using rodents. The suspension nature of this model was also exploited to minimize the boundary effects that complicate the interpretation of primary blast studies using surface cultures. Using this system, brain tissue was found not only to be sensitive to pressure changes, but also able to discriminate between the highly defined single-pulse shock waves produced by underwater blast and the complex pressure history exposures experienced by aggregates encased within a sphere and subjected to simulated air blast. The nature of blast-induced primary TBI requires a multidisciplinary research approach that addresses the fidelity of the blast insult, its accurate measurement and characterization, as well as the limitations of the biological models used.

A geophysical shock and air blast simulator at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Fournier, K. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, C. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); May, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Compton, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walton, O. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shingleton, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kane, J. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Holtmeier, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Loey, H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mirkarimi, P. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dunlop, W. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Guyton, R. L. [National Security Technologies, Livermore, CA (United States); Huffman, E. [National Security Technologies, Livermore, CA (United States)

2014-09-01

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.

A geophysical shock and air blast simulator at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Fournier, K. B.; Brown, C. G.; May, M. J.; Compton, S.; Walton, O. R.; Shingleton, N.; Kane, J. O.; Holtmeier, G.; Loey, H.; Mirkarimi, P. B.; Dunlop, W. H. [Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550 (United States); Guyton, R. L.; Huffman, E. [National Securities Technologies, Vasco Rd., Livermore, California 94551 (United States)

2014-09-15

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.

Supernova blast wave within a stellar cluster outflow

Science.gov (United States)

Rodríguez-Ramírez, J. C.; Raga, A. C.; Velázquez, P. F.; Rodríguez-González, A.; Toledo-Roy, J. C.

2014-11-01

In this paper, we develop a semi-analytic model of a supernova which goes off in the centre of a stellar cluster. The supernova remnant interacts with a stratified, pre-existent outflow produced by the winds of the cluster stars. We compare our semi-analytic model with numerical simulations using the spherically symmetric Euler equations with appropriate mass and energy source terms. We find good agreement between these two approaches, and we find that for typical parameters the blast wave is likely to reach the Taylor-Sedov regime outside the cluster radius. We also calculate the predicted X-ray luminosity of the flow as a function of time, and we obtain its dependence on the outer radius and the number of stars of the cluster.

Modeling and simulation of explosion effectiveness as a function of blast and crowd characteristics

Science.gov (United States)

Usmani, Zeeshan-Ul-Hassan

Suicide bombing has become one of the most lethal and favorite modus operandi of terrorist organizations around the world. On average, there is a suicide bombing attack every six days somewhere in the world. While various attempts have been made to assess the impact of explosions on structures and military personnel, little has been done on modeling the impact of a blast wave on a crowd in civilian settings. The assessment of an explosion's effect on a crowd can lead to better management of disasters, triage of patients, locating blast victims under the debris, development of protective gear, and safe distance recommendations to reduce the casualties. The overall goal of this work is to predict the magnitude of injuries and lethality on humans from a blast-wave with various explosive and crowd characteristics, and to compare, contrast, and analyze the performance of explosive and injury models against the real-life data of suicide bombing incidents. This thesis introduces BlastSim---a physics based stationary multi-agent simulation platform to model and simulate a suicide bombing event. The agents are constrained by the physical characteristics and mechanics of the blast wave. The BlastSim is programmed to test, analyze, and validate the results of different model combinations under various conditions with different sets of parameters, such as the crowd and explosive characteristics, blockage and human shields, fragmentation and the bomber's position, in 2-dimensional and 3-dimensional environments. The suicide bombing event can be re-created for forensic analysis. The proposed model combinations show a significant performance---the Harold Brode explosive model with Catherine Lee injury model using the blockage stands out consistently to be the best with an overall cumulative accuracy of 87.6%. When comparing against actual data, overall, prediction accuracy can be increased by 71% using this model combination. The J. Clutter with Reflection explosive model using

Blast wave injury prediction models for complex scenarios

NARCIS (Netherlands)

Teland, J.A.; Doormaal, J.C.A.M. van

2012-01-01

Blast waves from explosions can cause lethal injuries to humans. Development of injury criteria has been ongoing for many years, but with the main focus on free field conditions. However, with terrorist actions as a new threat, explosions in urban areas have become of much more interest. Urban areas

Distinguishing Realistic Military Blasts from Firecrackers in Mitigation Studies of Blast Induced Traumatic Brain Injury

Energy Technology Data Exchange (ETDEWEB)

Moss, W C; King, M J; Blackman, E G

2011-01-21

In their Contributed Article, Nyein et al. (1,2) present numerical simulations of blast waves interacting with a helmeted head and conclude that a face shield may significantly mitigate blast induced traumatic brain injury (TBI). A face shield may indeed be important for future military helmets, but the authors derive their conclusions from a much smaller explosion than typically experienced on the battlefield. The blast from the 3.16 gm TNT charge of (1) has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 10 atm, 0.25 ms, and 3.9 psi-ms at the front of the head (14 cm from charge), and 1.4 atm, 0.32 ms, and 1.7 psi-ms at the back of a typical 20 cm head (34 cm from charge). The peak pressure of the wave decreases by a factor of 7 as it traverses the head. The blast conditions are at the threshold for injury at the front of the head, but well below threshold at the back of the head (4). The blast traverses the head in 0.3 ms, roughly equal to the positive phase duration of the blast. Therefore, when the blast reaches the back of the head, near ambient conditions exist at the front. Because the headform is so close to the charge, it experiences a wave with significant curvature. By contrast, a realistic blast from a 2.2 kg TNT charge ({approx} an uncased 105 mm artillery round) is fatal at an overpressure of 10 atm (4). For an injury level (4) similar to (1), a 2.2 kg charge has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 2.1 atm, 2.3 ms, and 18 psi-ms at the front of the head (250 cm from charge), and 1.8 atm, 2.5 ms, and 16.8 psi-ms at the back of the head (270 cm from charge). The peak pressure decreases by only a factor of 1.2 as it traverses the head. Because the 0.36 ms traversal time is much smaller than the positive phase duration, pressures on the head become relatively uniform when the blast reaches the back of the head. The larger standoff implies

Performance testing of lead free primers: blast waves, velocity variations, and environmental testing

OpenAIRE

Courtney, Elya; Courtney, Amy; Summer, Peter David; Courtney, Michael

2014-01-01

Results are presented for lead free primers based on diazodinitrophenol (DDNP)compared with tests on lead styphnate based primers. First, barrel friction measurements in 5.56 mm NATO are presented. Second, shot to shot variations in blast waves are presented as determined by detonating primers in a 7.62x51mm rifle chamber with a firing pin, but without any powder or bullet loaded and measuring the blast wave at the muzzle with a high speed pressure transducer. Third, variations in primer blas...

Effects of blast wave to main steam piping under high energy line break condition by TNT model

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung Hyun; Lee, Eung Seok; Chang, Yoon Suk [Kyung Hee University, Yongin (Korea, Republic of)

2016-05-15

The aim of this study is to examine effect of the blast wave according to pipe break position through FE (Finite Element) analyses. If HELB (High Energy Line Break) accident occurs in nuclear power plants, not only environmental effect such as release of radioactive material but also secondary structural defects should be considered. Sudden pipe rupture causes ejection of high temperature and pressure fluid, which acts as a blast wave around the break location. The blast wave caused by the HELB has a possibility to induce structural defects around the components such as safe-related injection pipes and other structures.

High resolution imaging of colliding blast waves in cluster media

Energy Technology Data Exchange (ETDEWEB)

Smith, Roland A [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Lazarus, James [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Hohenberger, Matthias [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Marocchino, Alberto [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Robinson, Joseph S [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Chittenden, Jeremy P [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Moore, Alastair S [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Gumbrell, Edward T [Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ (United Kingdom); Dunne, Mike [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 OQX (United Kingdom)

2007-12-15

Strong shocks and blast wave collisions are commonly observed features in astrophysical objects such as nebulae and supernova remnants. Numerical simulations often underpin our understanding of these complex systems, however modelling of such extreme phenomena remains challenging, particularly so for the case of radiative or colliding shocks. This highlights the need for well-characterized laboratory experiments both to guide physical insight and to provide robust data for code benchmarking. Creating a sufficiently high-energy-density gas medium for conducting scaled laboratory astrophysics experiments has historically been problematic, but the unique ability of atomic cluster gases to efficiently couple to intense pulses of laser light now enables table top scale (1 J input energy) studies to be conducted at gas densities of >10{sup 19} particles cm{sup -3} with an initial energy density >5 x 10{sup 9} J g{sup -1}. By laser heating atomic cluster gas media we can launch strong (up to Mach 55) shocks in a range of geometries, with and without radiative precursors. These systems have been probed with a range of optical and interferometric diagnostics in order to retrieve electron density profiles and blast wave trajectories. Colliding cylindrical shock systems have also been studied, however the strongly asymmetric density profiles and radial and longitudinal mass flow that result demand a more complex diagnostic technique based on tomographic phase reconstruction. We have used the 3D magnetoresistive hydrocode GORGON to model these systems and to highlight interesting features such as the formation of a Mach stem for further study.

Dissipation of Impact Stress Waves within the Artificial Blasting Damage Zone in the Surrounding Rocks of Deep Roadway

Directory of Open Access Journals (Sweden)

Jianguo Ning

2016-01-01

Full Text Available Artificial explosions are commonly used to prevent rockburst in deep roadways. However, the dissipation of the impact stress wave within the artificial blasting damage zone (ABDZ of the rocks surrounding a deep roadway has not yet been clarified. The surrounding rocks were divided into the elastic zone, blasting damage zone, plastic zone, and anchorage zone in this research. Meanwhile, the ABDZ was divided into the pulverizing area, fractured area, and cracked area from the inside out. Besides, the model of the normal incidence of the impact stress waves in the ABDZ was established; the attenuation coefficient of the amplitude of the impact stress waves was obtained after it passed through the intact rock mass, and ABDZ, to the anchorage zone. In addition, a numerical simulation was used to study the dynamic response of the vertical stress and impact-induced vibration energy in the surrounding rocks. By doing so, the dissipation of the impact stress waves within the ABDZ of the surrounding rocks was revealed. As demonstrated in the field application, the establishment of the ABDZ in the surrounding rocks reduced the effect of the impact-induced vibration energy on the anchorage support system of the roadway.

Simulation of crack propagation in rock in plasma blasting technology

Science.gov (United States)

Ikkurthi, V. R.; Tahiliani, K.; Chaturvedi, S.

Plasma Blasting Technology (PBT) involves the production of a pulsed electrical discharge by inserting a blasting probe in a water-filled cavity drilled in a rock, which produces shocks or pressure waves in the water. These pulses then propagate into the rock, leading to fracture. In this paper, we present the results of two-dimensional hydrodynamic simulations using the SHALE code to study crack propagation in rock. Three separate issues have been examined. Firstly, assuming that a constant pressure P is maintained in the cavity for a time τ , we have determined the P- τ curve that just cracks a given rock into at least two large-sized parts. This study shows that there exists an optimal pressure level for cracking a given rock-type and geometry. Secondly, we have varied the volume of water in which the initial energy E is deposited, which corresponds to different initial peak pressures Ppeak. We have determined the E- Ppeak curve that just breaks the rock into four large-sized parts. It is found that there must be an optimal Ppeak that lowers the energy consumption, but with acceptable probe damage. Thirdly, we have attempted to identify the dominant mechanism of rock fracture. We also highlight some numerical errors that must be kept in mind in such simulations.

The Foulness multi-ton air blast simulator. Part 2. Recent developments - the linear charge driven facility

International Nuclear Information System (INIS)

Clare, P.M.

1978-02-01

The gun-driven facility for simulating nuclear air blast has been described in Part 1 (AWRE Report 031/74). It was, however, subject to certain limitations in providing the requisite blast parameters for nuclear hardening. The efficiency of the simulator has been improved beyond that of the gun-driven facility to produce blast waves of higher peak overpressure, longer positive duration and greater equivalent yield. This has been done by firing in the 1.8 m (6 ft) diameter section of the tunnel instead of in the guns. Various line charge arrangements were investigated and the pressures and strains developed in the 1.8 m (6 ft) diameter section were measured. The shock loading on the tube walls was less than that produced by firing in the guns and consisted of a short duration shock decaying to a lower amplitude pressure pulse of longer duration (1 ms), followed by a few reflected shocks which the tube walls were well able to withstand. The equipment is described and results discussed. (author)

Modeling blast waves, gas and particles dispersion in urban and hilly ground areas

International Nuclear Information System (INIS)

Hank, S.; Saurel, R.; Le Metayer, O.; Lapebie, E.

2014-01-01

The numerical simulation of shock and blast waves as well as particles dispersion in highly heterogeneous media such as cities, urban places, industrial plants and part of countries is addressed. Examples of phenomena under study are chemical gas products dispersion from damaged vessels, gas dispersion in urban places under explosion conditions, shock wave propagation in urban environment. A three-dimensional simulation multiphase flow code (HI2LO) is developed in this aim. To simplify the consideration of complex geometries, a heterogeneous discrete formulation is developed. When dealing with large scale domains, such as countries, the topography is considered with the help of elevation data. Meteorological conditions are also considered, in particular regarding complex temperature and wind profiles. Heat and mass transfers on sub-scale objects, such as buildings, trees and other obstacles are considered as well. Particles motion is addressed through a new turbulence model involving a single parameter to describe accurately plumes. Validations against experiments in basic situations are presented as well as examples of industrial and environmental computations. (authors)

Quality of computerized blast load simulation for non-linear dynamic ...

African Journals Online (AJOL)

Quality of computerized blast load simulation for non-linear dynamic response ... commercial software system and a special-purpose, blast-specific software product to ... depend both on the analysis model of choice and the stand-off distances.

Finite Element Simulation of Medium-Range Blast Loading Using LS-DYNA

Directory of Open Access Journals (Sweden)

Yuzhen Han

2015-01-01

Full Text Available This study investigated the Finite Element simulation of blast loading using LS-DYNA. The objective is to identify approaches to reduce the requirement of computation effort while maintaining reasonable accuracy, focusing on blast loading scheme, element size, and its relationship with scale of explosion. The study made use of the recently developed blast loading scheme in LS-DYNA, which removes the necessity to model the explosive in the numerical models but still maintains the advantages of nonlinear fluid-structure interaction. It was found that the blast loading technique could significantly reduce the computation effort. It was also found that the initial density of air in the numerical model could be purposely increased to partially compensate the error induced by the use of relatively large air elements. Using the numerical approach, free air blast above a scaled distance of 0.4 m/kg1/3 was properly simulated, and the fluid-structure interaction at the same location could be properly duplicated using proper Arbitrary Lagrangian Eulerian (ALE coupling scheme. The study also showed that centrifuge technique, which has been successfully employed in model tests to investigate the blast effects, may be used when simulating the effect of medium- to large-scale explosion at small scaled distance.

Large Blast and Thermal Simulator Reflected Wave Eliminator Study

Science.gov (United States)

1990-03-01

it delays the passage of this wave through the test section until after the test is complete. The required length of extra duct depends on the strength...tube axis, which acts like an additional contraction effect since Se = Sj/[Cqsin(aj)]. Tii extra area is illustrated best by plotting (Se-Ae)/Ac versus...34Simulation de Choc et de Soaffie. Comimpensateur d’Ondes de Detente de Bouche pour tube a Choc de 2400 mm de diametre de Veine. Description, Compte- Renda

Numerical Simulation of Blast Action on Civil Structures in Urban Environment

Science.gov (United States)

Valger, Svetlana A.; Fedorova, Natalya N.; Fedorov, Alexander V.

2017-10-01

Nowadays, a lot of industrial accidents accompanied by explosions are happening throughout the world. Also, increase in the number of terrorist acts committed by means of explosions is observed. For improving safety of buildings and structures it is necessary to raise their resistance to explosive effects, as well as to be able to predict degree of potential damage upon explosive loads of various intensities. One of the principal goals in designing the structure resistant to explosive effects is to determine the dynamic response of structures to the impact of the blast wave. To this end, the transient pressure loads on the walls of the civil engineering structures are to be determined. The simulation of explosion is highly complicated, involving an explosion causing the shock wave propagation in air and then interaction with a structure. The engineering-level techniques permit one to estimate an explosive shock impact only for isolated buildings. The complexity of the building, the presence of nearby structures and the surrounding environment cannot be taken into account. Advanced computer aid engineering (CAE) software techniques combined with the latest methods of discrete three-dimensional city modelling permits one to simulate and analyse the effects of explosions in urban areas with a precision which previously was not possible. In the paper, the simulation results are presented of shock wave forming due to a spherical explosive charge and its propagation in the vicinity of geometrical configuration imitating an urban environment. The numerical simulation of a flow in the vicinity of prisms of different cross-sections and heights located on a flat plate was performed. The calculations are carried out in a three-dimensional non-viscous formulation using ANSYS software. On a basis of simulation results, a complex wave structures were analysed, and all the peculiarities of flows and pressure history records on building walls were described and explained. The

Brain response to primary blast wave using validated finite element models of human head and advanced combat helmet

Directory of Open Access Journals (Sweden)

Liying eZhang

2013-08-01

Full Text Available Blast-induced traumatic brain injury has emerged as a signature injury in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH, a finite element (FE study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27-0.66 MPa from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP in the head ranged from 0.68-1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10-35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44% was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%. The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence "iso-damage" curves for brain injury are likely different than the Bowen curves

Localization of small arms fire using acoustic measurements of muzzle blast and/or ballistic shock wave arrivals.

Science.gov (United States)

Lo, Kam W; Ferguson, Brian G

2012-11-01

The accurate localization of small arms fire using fixed acoustic sensors is considered. First, the conventional wavefront-curvature passive ranging method, which requires only differential time-of-arrival (DTOA) measurements of the muzzle blast wave to estimate the source position, is modified to account for sensor positions that are not strictly collinear (bowed array). Second, an existing single-sensor-node ballistic model-based localization method, which requires both DTOA and differential angle-of-arrival (DAOA) measurements of the muzzle blast wave and ballistic shock wave, is improved by replacing the basic external ballistics model (which describes the bullet's deceleration along its trajectory) with a more rigorous model and replacing the look-up table ranging procedure with a nonlinear (or polynomial) equation-based ranging procedure. Third, a new multiple-sensor-node ballistic model-based localization method, which requires only DTOA measurements of the ballistic shock wave to localize the point of fire, is formulated. The first method is applicable to situations when only the muzzle blast wave is received, whereas the third method applies when only the ballistic shock wave is received. The effectiveness of each of these methods is verified using an extensive set of real data recorded during a 7 day field experiment.

Effectiveness of eye armor during blast loading.

Science.gov (United States)

Bailoor, Shantanu; Bhardwaj, Rajneesh; Nguyen, Thao D

2015-11-01

Ocular trauma is one of the most common types of combat injuries resulting from the interaction of military personnel with improvised explosive devices. Ocular blast injury mechanisms are complex, and trauma may occur through various injury mechanisms. However, primary blast injuries (PBI) are an important cause of ocular trauma that may go unnoticed and result in significant damage to internal ocular tissues and visual impairment. Further, the effectiveness of commonly employed eye armor, designed for ballistic and laser protection, in lessening the severity of adverse blast overpressures (BOP) is unknown. In this paper, we employed a three-dimensional (3D) fluid-structure interaction computational model for assessing effectiveness of the eye armor during blast loading on human eyes and validated results against free field blast measurements by Bentz and Grimm (2013). Numerical simulations show that the blast waves focused on the ocular region because of reflections from surrounding facial features and resulted in considerable increase in BOP. We evaluated the effectiveness of spectacles and goggles in mitigating the pressure loading using the computational model. Our results corroborate experimental measurements showing that the goggles were more effective than spectacles in mitigating BOP loading on the eye. Numerical results confirmed that the goggles significantly reduced blast wave penetration in the space between the armor and the eyes and provided larger clearance space for blast wave expansion after penetration than the spectacles. The spectacles as well as the goggles were more effective in reducing reflected BOP at higher charge mass because of the larger decrease in dynamic pressures after the impact. The goggles provided greater benefit of reducing the peak pressure than the spectacles for lower charge mass. However, the goggles resulted in moderate, sustained elevated pressure loading on the eye, that became 50-100% larger than the pressure loading

Blast event simulation for a structure subjected to a landmine explosion

NARCIS (Netherlands)

Sun, J.; Vlahopoulos, N.; Stabryla, T.J.; Goetz, R.; Velde, R. van de

2006-01-01

One of the main threats to military vehicles originates from landmine blasts. In order to improve the survivability of the occupants it is important to design a military vehicle for increased occupant safety. Simulation technology that combines modeling of the blast loads from the landmine

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

Science.gov (United States)

Pontalier, Q.; Loiseau, J.; Goroshin, S.; Frost, D. L.

2018-05-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/ C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/ C (compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/ C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

Science.gov (United States)

Pontalier, Q.; Loiseau, J.; Goroshin, S.; Frost, D. L.

2018-04-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/C (pressure levels in the mid-to-far field. Solid particles are more effective at mitigating the blast overpressure than liquids, particularly in the near field and at low values of M/C, suggesting that the energy dissipation during compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Field of infrasound wave on the earth from blast wave, produced by supersonic flight of a rocket

International Nuclear Information System (INIS)

Drobzheva, Ya.V.; Krasnov, V.M.

2006-01-01

It was developed a physical model, which allowed calculating a field of infrasound wave on the earth from blast wave, produced by supersonic flight of a rocket. For space launching site Baikonur it is shown that the nearest horizontal distance from launching site of rocket up to which arrive infrasound waves, produced by supersonic flight of a rocket, is 56 km. Amplitude of acoustic impulse decreases in 5 times on distance of 600 km. Duration of acoustic impulse increases from 1.5 to 3 s on the same distance. Values of acoustic field parameters on the earth surface, practically, do not depend from season of launching of rocket. (author)

Blast-Induced Acceleration in a Shock Tube: Distinguishing Primary and Tertiary Blast Injury

Science.gov (United States)

2016-10-01

injury conditions (blast and acceleration vs acceleration alone) undergo neurobehavioral and histopathological assessments to comprehensively... reversal . To facilitate mid-air blasts, a release mechanism was devised. Balls were attached to the bail of the mechanism. The blast wave would cause

Examination of the protective roles of helmet/faceshield and directionality for human head under blast waves.

Science.gov (United States)

Sarvghad-Moghaddam, Hesam; Jazi, Mehdi Salimi; Rezaei, Asghar; Karami, Ghodrat; Ziejewski, Mariusz

2015-01-01

A parametric study was conducted to delineate the efficacy of personal protective equipment (PPE), such as ballistic faceshields and advanced combat helmets, in the case of a blast. The propagations of blast waves and their interactions with an unprotected head, a helmeted one, and a fully protected finite element head model (FEHM) were modeled. The biomechanical parameters of the brain were recorded when the FEHM was exposed to shockwaves from the front, back, top, and bottom. The directional dependent tissue response of the brain and the variable efficiency of PPE with respect to the blast orientation were two major results of this study.

Time development of a blast wave with shock heated electrons

International Nuclear Information System (INIS)

Edgar, R.J.; Cox, D.P.

1983-01-01

Accurate approximations are presented for the time development of both edge conditions and internal structures of a blast wave with shock heated electrons, and equal ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform ambient density case) and have negligible external pressure. Account is taken of possible saturation of the thermal conduction flux. The structures evolve smoothly to the adiabatic structures

A Phased Array Approach to Rock Blasting

Energy Technology Data Exchange (ETDEWEB)

Leslie Gertsch; Jason Baird

2006-07-01

A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

Blast wave interaction with a rigid surface

International Nuclear Information System (INIS)

Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.

2004-01-01

A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)

Design of blast simulators for nuclear testing

International Nuclear Information System (INIS)

Mark, A.; Opalka, K.O.; Kitchens, C.W. Jr.

1983-01-01

A quasi-one-dimensional computational technique is used to model the flow of a large, complicated shock tube. The shock tube, or Large Blast Simulator, is used to simulate conventional or nuclear explosions by shaping the pressure history. Results from computations show favorable agreement when compared with data taken in the facility at Gramat, France. Such future shock tubes will include a thermal irradiation capability to better simulate a nuclear event. The computations point to the need for venting of the combustion products since the pressure history will be considerably altered as the shock propagates through these hot gases

Simulation for the powder movement and accumulation in the lower part of blast furnace

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Takashi [Mineral Resources Research Center, Nippon Steel Technoresearch, Futtsu-shi Chiba (Japan)

1998-12-31

The behavior of unburnt char and coke powder in the blast furnace becomes material for discussion with the increase in injection rate of pulverized coal into the blast furnace. An analysis was made as to the simulation of powder accumulation at the deadman and dripping zone of blast furnace by using a powder/gas two-phases flow experimental data. When an excessive powder has penetrated at a low gas velocity, it brings an increment in holdup and the controlling factors are powder/gas ratio and gas velocity. An empirical formula used for estimating the powder hold-up in the blast furnace internal conditions has proposed based on similarity. The controlling {pi} numbers are Floude number, powder/gas ratio and particle diameter ratio of powder/lump. This empirical formular was connected with Blast Furnace Total Model `BRIGHT` for the simulation of powder amount distribution in the lower part of blast furnace. When Powder diameter Dk exceeds 100 {mu} and gas velocity becomes lower than 0.7m/s at PC1OOkg/T, the powder tends to accumulate in the deadman. These results was available for the decision of optimum blast conditions and optimum powder diameter in the high amount of pulverized coal injection to the blast furnace. (author) 10 refs.

Simulation for the powder movement and accumulation in the lower part of blast furnace

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Takashi [Mineral Resources Research Center, Nippon Steel Technoresearch, Futtsu-shi Chiba (Japan)

1997-12-31

The behavior of unburnt char and coke powder in the blast furnace becomes material for discussion with the increase in injection rate of pulverized coal into the blast furnace. An analysis was made as to the simulation of powder accumulation at the deadman and dripping zone of blast furnace by using a powder/gas two-phases flow experimental data. When an excessive powder has penetrated at a low gas velocity, it brings an increment in holdup and the controlling factors are powder/gas ratio and gas velocity. An empirical formula used for estimating the powder hold-up in the blast furnace internal conditions has proposed based on similarity. The controlling {pi} numbers are Floude number, powder/gas ratio and particle diameter ratio of powder/lump. This empirical formular was connected with Blast Furnace Total Model `BRIGHT` for the simulation of powder amount distribution in the lower part of blast furnace. When Powder diameter Dk exceeds 100 {mu} and gas velocity becomes lower than 0.7m/s at PC1OOkg/T, the powder tends to accumulate in the deadman. These results was available for the decision of optimum blast conditions and optimum powder diameter in the high amount of pulverized coal injection to the blast furnace. (author) 10 refs.

Monte Carlo simulation as a tool to predict blasting fragmentation based on the Kuz Ram model

Science.gov (United States)

Morin, Mario A.; Ficarazzo, Francesco

2006-04-01

Rock fragmentation is considered the most important aspect of production blasting because of its direct effects on the costs of drilling and blasting and on the economics of the subsequent operations of loading, hauling and crushing. Over the past three decades, significant progress has been made in the development of new technologies for blasting applications. These technologies include increasingly sophisticated computer models for blast design and blast performance prediction. Rock fragmentation depends on many variables such as rock mass properties, site geology, in situ fracturing and blasting parameters and as such has no complete theoretical solution for its prediction. However, empirical models for the estimation of size distribution of rock fragments have been developed. In this study, a blast fragmentation Monte Carlo-based simulator, based on the Kuz-Ram fragmentation model, has been developed to predict the entire fragmentation size distribution, taking into account intact and joints rock properties, the type and properties of explosives and the drilling pattern. Results produced by this simulator were quite favorable when compared with real fragmentation data obtained from a blast quarry. It is anticipated that the use of Monte Carlo simulation will increase our understanding of the effects of rock mass and explosive properties on the rock fragmentation by blasting, as well as increase our confidence in these empirical models. This understanding will translate into improvements in blasting operations, its corresponding costs and the overall economics of open pit mines and rock quarries.

Primary blast-induced traumatic brain injury: lessons from lithotripsy

Science.gov (United States)

Nakagawa, A.; Ohtani, K.; Armonda, R.; Tomita, H.; Sakuma, A.; Mugikura, S.; Takayama, K.; Kushimoto, S.; Tominaga, T.

2017-11-01

Traumatic injury caused by explosive or blast events is traditionally divided into four mechanisms: primary, secondary, tertiary, and quaternary blast injury. The mechanisms of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury mechanism is associated with the response of brain tissue to the initial blast wave. Among the four mechanisms of bTBI, there is a remarkable lack of information regarding the mechanism of primary bTBI. On the other hand, 30 years of research on the medical application of shock waves (SWs) has given us insight into the mechanisms of tissue and cellular damage in bTBI, including both air-mediated and underwater SW sources. From a basic physics perspective, the typical blast wave consists of a lead SW followed by shock-accelerated flow. The resultant tissue injury includes several features observed in primary bTBI, such as hemorrhage, edema, pseudo-aneurysm formation, vasoconstriction, and induction of apoptosis. These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation are all important factors in determining the extent of SW-induced tissue and cellular injury. In addition, neuropsychiatric aspects of blast events need to be taken into account, as evidenced by reports of comorbidity and of some similar symptoms between physical injury resulting in bTBI and the psychiatric sequelae of post-traumatic stress. Research into blast injury biophysics is important to elucidate specific pathophysiologic mechanisms of blast injury, which enable accurate differential diagnosis, as well as development of effective treatments. Herein we describe the requirements for an adequate experimental setup when investigating blast-induced tissue and cellular injury; review SW physics

Modelling human eye under blast loading.

Science.gov (United States)

Esposito, L; Clemente, C; Bonora, N; Rossi, T

2015-01-01

Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues.

A Numerical Method for Blast Shock Wave Analysis of Missile Launch from Aircraft

Directory of Open Access Journals (Sweden)

Sebastian Heimbs

2015-01-01

Full Text Available An efficient empirical approach was developed to accurately represent the blast shock wave loading resulting from the launch of a missile from a military aircraft to be used in numerical analyses. Based on experimental test series of missile launches in laboratory environment and from a helicopter, equations were derived to predict the time- and position-dependent overpressure. The method was finally applied and validated in a structural analysis of a helicopter tail boom under missile launch shock wave loading.

Consideration on local blast vibration control by delay blasting; Danpatsu happa ni yoru kyokuchiteki shindo seigyo ni kansuru ichikosatsu

Energy Technology Data Exchange (ETDEWEB)

Mogi, Gento; Adachi, Tsuyoshi; Yamatomi, Jiro [The University of Tokyo School of Engineering Department of Geosystem Engineering, Tokyo (Japan); Hoshino, Tatsuya [Mitsui Mining and Smelting Corp., Tokyo (Japan)

1999-10-31

In this research, local blast vibration control based on the theory of superposition of waves was investigated. Firstly, the influence of delay time errors of conventional electric detonators upon the level of local blast vibration was examined. Secondly, for a further effective local blast vibration control, a new delay blasting design concept 'combined delay blasting' that postulates the use of electronic detonators, which virtually have no delay time errors, is proposed. For a delay blasting with uniform detonation time intervals, an optimum time interval to minimize the local PPV (Peak Particle Velocity) is obtained based on the relationship between the PPV and the time interval, which is derived by superposing identical vibration time histories of each single hole shot. However, due to the scattering of the actual delay time caused by errors, PPV of a production blast seldom coincides with the estimated one. Since the expected value and the variance of PPV mainly depend on sensitivity of PPV around the nominal delay time, it is proposed that not only the optimum but also several sub-optimum candidates of delay time should be examined taking error into consideration. Concerning the 'combined delay blasting', its concept and some simulation results are presented. The estimated reduction effect of blast vibration of a delay blast based on this concept was quite favorable, indicating a possibility for further effective local blast vibration control. (author)

The Air Blast Wave from a Nuclear Explosion

Science.gov (United States)

Reines, Frederick

The sudden, large scale release of energy in the explosion of a nuclear bomb in air gives rise, in addition to nuclear emanations such as neutrons and gamma rays, to an extremely hot, rapidly expanding mass of air.** The rapidly expanding air mass has an initial temperature in the vicinity of a few hundred thousand degrees and for this reason it glows in its early stages with an intensity of many suns. It is important that the energy density in this initial "ball of fire" is of the order of 3 × 103 times that found in a detonating piece of TNT and hence that the initial stages of the large scale air motion produced by a nuclear explosion has no counterpart in an ordinary. H. E. explosion. Further, the relatively low temperatures ˜2,000°C associated with the initial stages of an H. E. detonation implies that the thermal radiation which it emits is a relatively insignificant fraction of the total energy involves. This point is made more striking when it is remembered that the thermal energy emitted by a hot object varies directly with the temperature in the Rayleigh Jeans region appropriate to the present discussion. The expansion of the air mass heated by the nuclear reaction produces, in qualitatively the same manner as in an H.E. explosion or the bursting of a high pressure balloon, an intense sharp pressure pulse, a shock wave, in the atmosphere. As the pressure pulse spreads outward it weakens due to the combined effects of divergence and the thermodynamically irreversible nature of the shock wave. The air comprising such a pressure pulse or blast wave moves first radially outward and then back towards the center as the blast wave passes. Since a permanent outward displacement of an infinite mass of air would require unlimited energy, the net outward displacement of the air distant from an explosion must approach zero with increasing distance. As the distance from the explosion is diminished the net outward displacement due to irreversible shock heating of

Air blasts generated by rockfall impacts: Analysis of the 1996 Happy Isles event in Yosemite National Park

Science.gov (United States)

Morrissey, M. M.; Savage, W. Z.; Wieczorek, G. F.

1999-10-01

The July 10, 1996, Happy Isles rockfall in Yosemite National Park, California, released 23,000 to 38,000 m3 of granite in four separate events. The impacts of the first two events which involved a 550-m free fall, generated seismic waves and atmospheric pressure waves (air blasts). We focus on the dynamic behavior of the second air blast that downed over 1000 trees, destroyed a bridge, demolished a snack bar, and caused one fatality and several injuries. Calculated velocities for the air blast from a two-phase, finite difference model are compared to velocities estimated from tree damage. From tornadic studies of tree damage, the air blast is estimated to have traveled <108-120 m/s within 50 m from the impact and decreased to <10-20 m/s within 500 m from the impact. The numerical model simulates the two-dimensional propagation of an air blast through a dusty atmosphere with initial conditions defined by the impact velocity and pressure. The impact velocity (105-107 m/s) is estimated from the Colorado Rockfall Simulation Program that simulates rockfall trajectories. The impact pressure (0.5 MPa) is constrained by the kinetic energy of the impact (1010-1012 J) estimated from the seismic energy generated by the impact. Results from the air blast simulations indicate that the second Happy Isles air blast (weak shock wave) traveled with an initial velocity above the local sound speed. The size and location of the first impact are thought to have injected <50 wt% dust into the atmosphere. This amount of dust lowered the local atmospheric sound speed to ˜220 m/s. The discrepancy between calculated velocity data and field estimated velocity data (˜220 m/s versus ˜110 m/s) is attributed to energy dissipated by the downing of trees and additional entrainment of debris into the atmosphere not included in the calculations.

Development of a Strategy for Simulating Blast-Vehicle Interactions

Science.gov (United States)

2010-09-01

Magnus effect . Although large rotational speeds were measured, it was concluded that the Magnus force had little influence and did not significantly...CHEM (rigid flat-plate). 104 Figure 5.3: Geometry used for blast wave interacting with a cylinder (Ofengeim and Drikakis 1997). 105 Figure 5.4: CFD...their effects on vehicles and their human occupants. The framework couples the MPMICE CFD code with DYNA3D and LS-DYNA finite element codes

Physics of IED blast shock tube simulations for mTBI research

NARCIS (Netherlands)

Mediavilla Varas, J.; Philippens, M.M.G.M.; Meijer, S.R.; Berg, A.C. van den; Sibma, P.C.; Bree, J.L.M.J. van; Vries, D.V.W.M. de

2011-01-01

Shock tube experiments and simulations are conducted with a spherical gelatin filled skull- brain surrogate, in order to study the mechanisms leading to blast induced mild traumatic brain injury. A shock tube including sensor system is optimized to simulate realistic impro-vised explosive device

Investigation of the Propagation Characteristics of Underwater Shock Waves in Underwater Drilling Blasting

Directory of Open Access Journals (Sweden)

Xin Liu

2018-01-01

Full Text Available During the first-stage project of the main channel of Ningbo-Zhoushan Port’s Shipu Harbor, underwater shock waves were monitored. By analyzing a typical measured pressure time history curve, the characteristics of underwater shock waves in an engineering context were obtained. We obtained a traditional exponential attenuation formula for underwater shock waves based on the measured data, simplified the model of underwater drilling blasting based on engineering practice, deduced a revised formula for underwater shock wave peak overpressure on the basis of dimensional analysis, established a linear fitting model, and obtained the undetermined coefficients of the revised formula using a linear regression analysis. In addition, the accuracies of the two formulas used to predict underwater shock wave peak overpressure and the significance order of influence and influence mechanism of factors included in the revised formula on the underwater shock wave peak overpressure were discussed.

Experiments on cylindrically converging blast waves in atmospheric air

Science.gov (United States)

Matsuo, Hideo; Nakamura, Yuichi

1980-06-01

Cylindrically converging blast waves have been produced in normal atmospheric conditions by the detonation of the explosives, pentaerythritoltetranitrate, (PETN), over cylindrical surfaces. The shocks generated in this way are so strong that the fronts propagating through the air become luminous of themselves. The production and the propagation of the shocks have been monitored with a framing camera and a streak camera, and the time-space relations of the shock propagations have been determined using an electrical ionization probing system. The results have shown that the trajectory of the shock fronts near the axis of the cylinder can be approximately represented by the Guderley's formula.

Spalling of concrete walls under blast load

International Nuclear Information System (INIS)

Kot, C.A.

1977-01-01

A common effect of the detonation of explosives in close proximity of concrete shield walls is the spalling (scabbing) of the back face of the wall. Spalling is caused by the free surface reflection of the shock wave induced in the wall by high pressure air blast and occurs whenever the dynamic tensile rupture strength is exceeded. While a complex process, reasonable analytical spall estimates can be obtained for brittle materials with low tensile strengths, such as concrete, by assuming elastic material behavior and instantaneous spall formation. Specifically, the spall thicknesses and velocities for both normal and oblique incidence of the shock wave on the back face of the wall are calculated. The complex exponential decay wave forms of the air blast are locally approximated by simple power law expressions. Variations of blast wave strength with distance to the wall, charge weight and angle of incidence are taken into consideration. The shock wave decay in the wall is also accounted for by assuming elastic wave propagation. For explosions close-in to the wall, where the reflected blast wave pressures are sufficiently high, multiple spall layers are formed. Successive spall layers are of increasing thickness, at the same time the spall velocities decrease. The spall predictions based on elastic theory are in overall agreement with experimntal results and provide a rapid means of estimating spalling trends of concrete walls subjected to air blast. (Auth.)

A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

Science.gov (United States)

Park, Dohyun; Jeon, Byungkyu; Jeon, Seokwon

2009-06-01

Blasting is often a necessary part of mining and construction operations, and is the most cost-effective way to break rock, but blasting generates both noise and ground vibration. In urban areas, noise and vibration have an environmental impact, and cause structural damage to nearby structures. Various wave-screening methods have been used for many years to reduce blast-induced ground vibration. However, these methods have not been quantitatively studied for their reduction effect of ground vibration. The present study focused on the quantitative assessment of the effectiveness in vibration reduction of line-drilling as a screening method using a numerical method. Two numerical methods were used to analyze the reduction effect toward ground vibration, namely, the “distinct element method” and the “non-linear hydrocode.” The distinct element method, by particle flow code in two dimensions (PFC 2D), was used for two-dimensional parametric analyses, and some cases of two-dimensional analyses were analyzed three-dimensionally using AUTODYN 3D, the program of the non-linear hydrocode. To analyze the screening effectiveness of line-drilling, parametric analyses were carried out under various conditions, with the spacing, diameter of drill holes, distance between the blasthole and line-drilling, and the number of rows of drill holes, including their arrangement, used as parameters. The screening effectiveness was assessed via a comparison of the vibration amplitude between cases both with and without screening. Also, the frequency distribution of ground motion of the two cases was investigated through fast Fourier transform (FFT), with the differences also examined. From our study, it was concluded that line-drilling as a screening method of blast-induced waves was considerably effective under certain design conditions. The design details for field application have also been proposed.

Piecewise parabolic method for simulating one-dimensional shear shock wave propagation in tissue-mimicking phantoms

Science.gov (United States)

Tripathi, B. B.; Espíndola, D.; Pinton, G. F.

2017-11-01

The recent discovery of shear shock wave generation and propagation in the porcine brain suggests that this new shock phenomenology may be responsible for a broad range of traumatic injuries. Blast-induced head movement can indirectly lead to shear wave generation in the brain, which could be a primary mechanism for injury. Shear shock waves amplify the local acceleration deep in the brain by up to a factor of 8.5, which may tear and damage neurons. Currently, there are numerical methods that can model compressional shock waves, such as comparatively well-studied blast waves, but there are no numerical full-wave solvers that can simulate nonlinear shear shock waves in soft solids. Unlike simplified representations, e.g., retarded time, full-wave representations describe fundamental physical behavior such as reflection and heterogeneities. Here we present a piecewise parabolic method-based solver for one-dimensional linearly polarized nonlinear shear wave in a homogeneous medium and with empirical frequency-dependent attenuation. This method has the advantage of being higher order and more directly extendable to multiple dimensions and heterogeneous media. The proposed numerical scheme is validated analytically and experimentally and compared to other shock capturing methods. A Riemann step-shock problem is used to characterize the numerical dissipation. This dissipation is then tuned to be negligible with respect to the physical attenuation by choosing an appropriate grid spacing. The numerical results are compared to ultrasound-based experiments that measure planar polarized shear shock wave propagation in a tissue-mimicking gelatin phantom. Good agreement is found between numerical results and experiment across a 40 mm propagation distance. We anticipate that the proposed method will be a starting point for the development of a two- and three-dimensional full-wave code for the propagation of nonlinear shear waves in heterogeneous media.

Controlled Low-Pressure Blast-Wave Exposure Causes Distinct Behavioral and Morphological Responses Modelling Mild Traumatic Brain Injury, Post-Traumatic Stress Disorder, and Comorbid Mild Traumatic Brain Injury-Post-Traumatic Stress Disorder.

Science.gov (United States)

Zuckerman, Amitai; Ram, Omri; Ifergane, Gal; Matar, Michael A; Sagi, Ram; Ostfeld, Ishay; Hoffman, Jay R; Kaplan, Zeev; Sadot, Oren; Cohen, Hagit

2017-01-01

The intense focus in the clinical literature on the mental and neurocognitive sequelae of explosive blast-wave exposure, especially when comorbid with post-traumatic stress-related disorders (PTSD) is justified, and warrants the design of translationally valid animal studies to provide valid complementary basic data. We employed a controlled experimental blast-wave paradigm in which unanesthetized animals were exposed to visual, auditory, olfactory, and tactile effects of an explosive blast-wave produced by exploding a thin copper wire. By combining cognitive-behavioral paradigms and ex vivo brain MRI to assess mild traumatic brain injury (mTBI) phenotype with a validated behavioral model for PTSD, complemented by morphological assessments, this study sought to examine our ability to evaluate the biobehavioral effects of low-intensity blast overpressure on rats, in a translationally valid manner. There were no significant differences between blast- and sham-exposed rats on motor coordination and strength, or sensory function. Whereas most male rats exposed to the blast-wave displayed normal behavioral and cognitive responses, 23.6% of the rats displayed a significant retardation of spatial learning acquisition, fulfilling criteria for mTBI-like responses. In addition, 5.4% of the blast-exposed animals displayed an extreme response in the behavioral tasks used to define PTSD-like criteria, whereas 10.9% of the rats developed both long-lasting and progressively worsening behavioral and cognitive "symptoms," suggesting comorbid PTSD-mTBI-like behavioral and cognitive response patterns. Neither group displayed changes on MRI. Exposure to experimental blast-wave elicited distinct behavioral and morphological responses modelling mTBI-like, PTSD-like, and comorbid mTBI-PTSD-like responses. This experimental animal model can be a useful tool for elucidating neurobiological mechanisms underlying the effects of blast-wave-induced mTBI and PTSD and comorbid mTBI-PTSD.

A computational model of blast loading on the human eye.

Science.gov (United States)

Bhardwaj, Rajneesh; Ziegler, Kimberly; Seo, Jung Hee; Ramesh, K T; Nguyen, Thao D

2014-01-01

Ocular injuries from blast have increased in recent wars, but the injury mechanism associated with the primary blast wave is unknown. We employ a three-dimensional fluid-structure interaction computational model to understand the stresses and deformations incurred by the globe due to blast overpressure. Our numerical results demonstrate that the blast wave reflections off the facial features around the eye increase the pressure loading on and around the eye. The blast wave produces asymmetric loading on the eye, which causes globe distortion. The deformation response of the globe under blast loading was evaluated, and regions of high stresses and strains inside the globe were identified. Our numerical results show that the blast loading results in globe distortion and large deviatoric stresses in the sclera. These large deviatoric stresses may be indicator for the risk of interfacial failure between the tissues of the sclera and the orbit.

COLLIMATION AND ASYMMETRY OF THE HOT BLAST WAVE FROM THE RECURRENT NOVA V745 Sco

Energy Technology Data Exchange (ETDEWEB)

Drake, Jeremy J.; Kashyap, Vinay [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Delgado, Laura; Hernanz, M. [Institute of Space Sciences, ICE (CSIC-IEEC), E-08193 Cerdanyola del Vallés, Barcelona (Spain); Laming, J. Martin [Space Science Division, Naval Research Laboratory, Code 7674L, Washington, DC 20375 (United States); Starrfield, Sumner [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Orlando, Salvatore [INAF—Osservatorio Astronomico di Palermo G. S. Vaiana, Piazza del Parlamento 1, I-90134 Palermo (Italy); Page, Kim L. [Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom); Ness, J.-U. [Science Operations Division, Science Operations Department of ESA, ESAC, E-28691 Villanueva de la Cañada (Madrid) (Spain); Gehrz, R. D.; Woodward, Charles E. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Van Rossum, Daan [Flash Center for Computational Science, Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2016-07-10

The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 10{sup 7} K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s{sup 1}, an FWHM of 1200 ± 30 km s{sup 1}, and an average net blueshift of 165 ± 10 km s{sup 1}. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 10{sup 43} erg and confirms an ejected mass of approximately 10{sup 7} M {sub ⊙}. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.

Computer Simulation of Blast Waves in a Tunnel with Sudden Decrease in Cross Section

Energy Technology Data Exchange (ETDEWEB)

Glenn, L. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Neuscamman, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2011-08-22

The case of an explosion in a tunnel where the blast wave encounters a sudden decrease in cross section is studied with quasi-one-dimensional (1D) and two-dimensional axisymmetric codes (2D) and the results are compared to experimental data. It is found that the numerical results from both codes are in good agreement until the interface at the change in cross section is encountered. Thereafter, however, the peak pressure derived with the codes is found to be significantly higher than the experimental results although the agreement between the 2D result and the experiment improves with increasing distance down the tunnel. Peak pressure and impulse per unit area obtained downstream of the interface with the 1D analysis are found to be substantially higher than with either the experiment or the 2D results. The reason for this is the time delay for the shock reflecting off the (vertical) rigid wall between the inner and outer tunnel radii to interact with the (supersonic) core flow into the decreased cross section. In the 1D case the reflected and transmitted shocks are formed instantaneously across the entire cross section resulting in higher pressure and increased shock speed downstream of the interface.

A novel rat model of blast-induced traumatic brain injury simulating different damage degree: implications for morphological, neurological, and biomarker changes

Directory of Open Access Journals (Sweden)

Mengdong eLiu

2015-05-01

Full Text Available In current military conflicts and civilian terrorism, blast-induced traumatic brain injury (bTBI is the primary cause of neurotrauma. However, the effects and mechanisms of bTBI are poorly understood. Although previous researchers have made significant contributions to establishing animal models for the simulation of bTBI, the precision and controllability of blast-induced injury in animal models must be improved. Therefore, we established a novel rat model to simulate blast-wave injury to the brain. To simulate different extents of bTBI injury, the animals were divided into moderate and severe injury groups. The miniature spherical explosives (PETN used in each group were of different sizes (2.5 mm diameter in the moderate injury group and 3.0 mm diameter in the severe injury group. A specially designed apparatus was able to precisely adjust the positions of the miniature explosives and create eight rats with bTBI simultaneously, using a single electric detonator. Neurological functions, gross pathologies, histopathological changes and the expression levels of various biomarkers were examined after the explosion. Compared with the moderate injury group, there were significantly more neurological dysfunctions, cortical contusions, intraparenchymal hemorrhages, cortical expression of S-100β, MBP, NSE, IL-8, IL-10, iNOS and HIF-1α in the severe injury group. These results demonstrate that we have created a reliable and reproducible bTBI model in rats. This model will be helpful for studying the mechanisms of bTBI and developing strategies for clinical bTBI treatment.

Blast Overpressure Studies. Nonauditory Damage Risk Assessment for Simulated Muzzle Blast from a l2Omm Ml2l Mortar System

National Research Council Canada - National Science Library

Yelverton, John

1997-01-01

This study was undertaken to establish the subthreshold, threshold, and suprathresholds for nonauditory injuries in a simulated muzzle blast environment like that produced when firing a 120mm M121 mortar system...

International Symposium on Military Applications of Blast Simulation (5th)

Science.gov (United States)

1977-06-22

Centre d’Etudes de Grainat, Gramat , France, de- scribed their work in designing a blast simulator with a test section of 12—rn width and 7—rn height...de Gramat , Gramat , France) on the dynamic behavior of limestone. Through a series of high—pressure experiments of the type developed in the recent

Viscoelastic Materials Study for the Mitigation of Blast-Related Brain Injury

Science.gov (United States)

Bartyczak, Susan; Mock, Willis, Jr.

2011-06-01

Recent preliminary research into the causes of blast-related brain injury indicates that exposure to blast pressures, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficient to protect the warfighter from this danger and the effects are debilitating, costly, and long-lasting. Commercially available viscoelastic materials, designed to dampen vibration caused by shock waves, might be useful as helmet liners to dampen blast waves. The objective of this research is to develop an experimental technique to test these commercially available materials when subject to blast waves and evaluate their blast mitigating behavior. A 40-mm-bore gas gun is being used as a shock tube to generate blast waves (ranging from 1 to 500 psi) in a test fixture at the gun muzzle. A fast opening valve is used to release nitrogen gas from the breech to impact instrumented targets. The targets consist of aluminum/ viscoelastic polymer/ aluminum materials. Blast attenuation is determined through the measurement of pressure and accelerometer data in front of and behind the target. The experimental technique, calibration and checkout procedures, and results will be presented.

Numerical Simulation of Rock Mass Damage Evolution During Deep-Buried Tunnel Excavation by Drill and Blast

Science.gov (United States)

Yang, Jianhua; Lu, Wenbo; Hu, Yingguo; Chen, Ming; Yan, Peng

2015-09-01

Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by drill and blast, it is generally accepted that a combination of effects of stress redistribution and blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the blasting-induced damage. Influence of repeated blast loadings on the damage extension for practical millisecond delay blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by drill and blast.

Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

Energy Technology Data Exchange (ETDEWEB)

Moss, W C; King, M J; Blackman, E G

2009-04-30

Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

A PC-Based Tool for Coupled CFD and CSD Simulation of Blast-Barrier Responses

National Research Council Canada - National Science Library

Chen, Zen; Bewick, Bryan; Salim, Hani A; Kiger, Sam A; Dinan, Robert J; Hu, Wenquin

2006-01-01

... for predicting the responses of a blast barrier. An axisymmetrical model is formulated using a coupled CFD and CSD simulation procedure designed via the Material Point Method in spatial discretization...

A coupling of empirical explosive blast loads to ALE air domains in LS-DYNA (registered)

International Nuclear Information System (INIS)

Slavik, Todd P

2010-01-01

A coupling method recently implemented in LS-DYNA (registered) allows empirical explosive blast loads to be applied to air domains treated with the multi-material arbitrary Lagrangian-Eulerian (ALE) formulation. Previously, when simulating structures subjected to blast loads, two methods of analysis were available: a purely Lagrangian approach or one involving the ALE and Lagrangian formulations coupled with a fluid-structure interaction (FSI) algorithm. In the former, air blast pressure is computed with empirical equations and directly applied to Lagrangian elements of the structure. In the latter approach, the explosive as well as the air are explicitly modeled and the blast wave propagating through the ALE air domain impinges on the Lagrangian structure through FSI. Since the purely Lagrangian approach avoids modeling the air between the explosive and structure, a significant computational cost savings can be realized - especially so when large standoff distances are considered. The shortcoming of the empirical blast equations is their inability to account for focusing or shadowing of the blast waves due to their interaction with structures which may intervene between the explosive and primary structure of interest. The new method presented here obviates modeling the explosive and air leading up the structure. Instead, only the air immediately surrounding the Lagrangian structures need be modeled with ALE, while effects of the far-field blast are applied to the outer face of that ALE air domain with the empirical blast equations; thus, focusing and shadowing effects can be accommodated yet computational costs are kept to a minimum. Comparison of the efficiency and accuracy of this new method with other approaches shows that the ability of LS-DYNA (registered) to model a variety of new blast scenarios has been greatly extended.

Assessment of dynamic mechanical behaviour of reinforced concrete beams using a blast simulator

Directory of Open Access Journals (Sweden)

Peroni Marco

2015-01-01

Full Text Available Critical infrastructures may become the target of terrorist bombing attacks or may have to withstand explosive loads due to accidents. The impulsive load connected to explosions is delivered to the structure in a few milliseconds forcing it to respond or fail in a peculiar mode. With reference to the above scientific framework this work presents an innovative apparatus designed and developed at the European Laboratory for Structural Assessment to reproduce a blast pressure history without using explosives. This apparatus is practically a hybrid nitrogen-spring-driven actuator that accelerates masses of up to 100 kg to a maximum velocity of about 25 m/s that impact against the tested structure. The pressure-load history applied to the structure is modulated and reshaped using appropriate layers of elastic soft materials (such as polymeric foams placed between the specimen and the impacting masses. Specific instrumentation has extensively been utilised to investigate the blast simulator performance and to precisely measure the pressure loads applied to the specimen. A series of tests on real scale reinforced concrete beams/columns (250 × 250 × 2200 mm has been performed to efficiently assess the performance and potentiality of the new blast simulator. Results are under evaluation. In addition to the experimental work, a series of numerical simulations by means of the explicit FEM code EUROPLEXUS have been carried out to support and improve the equipment design.

Numerical investigation of particle-blast interaction during explosive dispersal of liquids and granular materials

Science.gov (United States)

Pontalier, Q.; Lhoumeau, M.; Milne, A. M.; Longbottom, A. W.; Frost, D. L.

2018-04-01

Experiments show that when a high-explosive charge with embedded particles or a charge surrounded by a layer of liquid or granular material is detonated, the flow generated is perturbed by the motion of the particles and the blast wave profile differs from that of an ideal Friedlander form. Initially, the blast wave overpressure is reduced due to the energy dissipation resulting from compaction, fragmentation, and heating of the particle bed, and acceleration of the material. However, as the blast wave propagates, particle-flow interactions collectively serve to reduce the rate of decay of the peak blast wave overpressure. Computations carried out with a multiphase hydrocode reproduce the general trends observed experimentally and highlight the transition between the particle acceleration/deceleration phases, which is not accessible experimentally, since the particles are obscured by the detonation products. The dependence of the particle-blast interaction and the blast mitigation effectiveness on the mitigant to explosive mass ratio, the particle size, and the initial solid volume fraction is investigated systematically. The reduction in peak blast overpressure is, as in experiments, primarily dependent on the mass ratio of material to explosive, with the particle size, density, and initial porosity of the particle bed playing secondary roles. In the near field, the blast overpressure decreases sharply with distance as the particles are accelerated by the flow. When the particles decelerate due to drag, energy is returned to the flow and the peak blast overpressure recovers and reaches values similar to that of a bare explosive charge for low mass ratios. Time-distance trajectory plots of the particle and blast wave motion with the pressure field superimposed, illustrate the weak pressure waves generated by the motion of the particle layer which travel upstream and perturb the blast wave motion. Computation of the particle and gas momentum flux in the multiphase

Numerical investigation of particle-blast interaction during explosive dispersal of liquids and granular materials

Science.gov (United States)

Pontalier, Q.; Lhoumeau, M.; Milne, A. M.; Longbottom, A. W.; Frost, D. L.

2018-05-01

Experiments show that when a high-explosive charge with embedded particles or a charge surrounded by a layer of liquid or granular material is detonated, the flow generated is perturbed by the motion of the particles and the blast wave profile differs from that of an ideal Friedlander form. Initially, the blast wave overpressure is reduced due to the energy dissipation resulting from compaction, fragmentation, and heating of the particle bed, and acceleration of the material. However, as the blast wave propagates, particle-flow interactions collectively serve to reduce the rate of decay of the peak blast wave overpressure. Computations carried out with a multiphase hydrocode reproduce the general trends observed experimentally and highlight the transition between the particle acceleration/deceleration phases, which is not accessible experimentally, since the particles are obscured by the detonation products. The dependence of the particle-blast interaction and the blast mitigation effectiveness on the mitigant to explosive mass ratio, the particle size, and the initial solid volume fraction is investigated systematically. The reduction in peak blast overpressure is, as in experiments, primarily dependent on the mass ratio of material to explosive, with the particle size, density, and initial porosity of the particle bed playing secondary roles. In the near field, the blast overpressure decreases sharply with distance as the particles are accelerated by the flow. When the particles decelerate due to drag, energy is returned to the flow and the peak blast overpressure recovers and reaches values similar to that of a bare explosive charge for low mass ratios. Time-distance trajectory plots of the particle and blast wave motion with the pressure field superimposed, illustrate the weak pressure waves generated by the motion of the particle layer which travel upstream and perturb the blast wave motion. Computation of the particle and gas momentum flux in the multiphase

Characterization of viscoelastic materials for low-magnitude blast mitigation

Science.gov (United States)

Bartyczak, S.; Mock, W.

2014-05-01

Recent research indicates that exposure to low amplitude blast waves, such as IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of the present work is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. The 40-mm-bore gas gun was used as a shock tube to generate blast waves (ranging from 0.5 to 2 bar) in the test fixture mounted on the gun muzzle. A fast opening valve was used to release helium gas from the breech which formed into a blast wave and impacted instrumented targets in the test fixture. Blast attenuation of selected materials was determined through the measurement of stress data in front of and behind the target. Materials evaluated in this research include polyurethane foam from currently fielded US Army and Marine Corps helmets, polyurea 1000, and three hardnesses of Sorbothane (48, 58, and 70 durometer, Shore 00). Polyurea 1000 and 6061-T6 aluminum were used to calibrate the stress gauges.

BLAST: Building energy simulation in Hong Kong

Science.gov (United States)

Fong, Sai-Keung

1999-11-01

The characteristics of energy use in buildings under local weather conditions were studied and evaluated using the energy simulation program BLAST-3.0. The parameters used in the energy simulation for the study and evaluation include the architectural features, different internal building heat load settings and weather data. In this study, mathematical equations and the associated coefficients useful to the industry were established. A technology for estimating energy use in buildings under local weather conditions was developed by using the results of this study. A weather data file of Typical Meteorological Years (TMY) has been compiled for building energy studies by analyzing and evaluating the weather of Hong Kong from the year 1979 to 1988. The weather data file TMY and the example weather years 1980 and 1988 were used by BLAST-3.0 to evaluate and study the energy use in different buildings. BLAST-3.0 was compared with other building energy simulation and approximation methods: Bin method and Degree Days method. Energy use in rectangular compartments of different volumes varying from 4,000 m3 to 40,000 m3 with different aspect ratios were analyzed. The use of energy in buildings with concrete roofs was compared with those with glass roofs at indoor temperature 21°C, 23°C and 25°C. Correlation relationships among building energy, space volume, monthly mean temperature and solar radiation were derived and investigated. The effects of space volume, monthly mean temperature and solar radiation on building energy were evaluated. The coefficients of the mathematical relationships between space volume and energy use in a building were computed and found satisfactory. The calculated coefficients can be used for quick estimation of energy use in buildings under similar situations. To study energy use in buildings, the cooling load per floor area against room volume was investigated. The case of an air-conditioned single compartment with 5 m ceiling height was

Higher-order anisotropies in the blast-wave model: Disentangling flow and density field anisotropies

Energy Technology Data Exchange (ETDEWEB)

Cimerman, Jakub [Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Comenius University, FMPI, Bratislava (Slovakia); Tomasik, Boris [Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Univerzita Mateja Bela, FPV, Banska Bystrica (Slovakia); Csanad, Mate; Loekoes, Sandor [Eoetvoes Lorand University, Budapest (Hungary)

2017-08-15

We formulate a generalisation of the blast-wave model which is suitable for the description of higher-order azimuthal anisotropies of the hadron production. The model includes anisotropy in the density profile as well as an anisotropy in the transverse expansion velocity field. We then study how these two kinds of anisotropies influence the single-particle distributions and the correlation radii of two-particle correlation functions. Particularly we focus on the third-order anisotropy and consideration is given averaging over different orientations of the event plane. (orig.)

Interaction of Supernova Blast Waves with Wind-Driven Shells: Formation of "Jets", "Bullets", "Ears", Etc.

Science.gov (United States)

Gvaramadze, V. V.

Most of middle-aged supernova remnants (SNRs) have a distorted and complicated appearance which cannot be explained in the framework of the Sedov-Taylor model. We consider three typical examples of such SNRs (Vela SNR, MSH15-52, G309.2-00.6) and show that their structure could be explained as a result of interaction of a supernova (SN) blast wave with the ambient medium preprocessed by the action of the SN progenitor's wind and ionized emission.

Blast-wave analysis of strange particle $m_{T}$ spectra in Pb-Pb collisions at the SPS

CERN Document Server

Bruno, Giuseppe E

2005-01-01

The transverse mass spectra of high statistics, high purity samples of K/sup 0//sub S/, Lambda , Xi and Omega particles produced in Pb-Pb collisions at SPS energy have been studied in the framework of the blast-wave model. The dependence of the freezeout parameters on particle species and event centrality is discussed. Results at 40 A GeV/c are presented here for the first time.

A multiscale approach to blast neurotrauma modeling:Part II: Methodology for inducing blast injury to in vitro models

Directory of Open Access Journals (Sweden)

Gwen B. Effgen

2012-02-01

Full Text Available Due to the prominent role of improvised explosive devices (IEDs in wounding patterns of U.S. war-fighters in Iraq and Afghanistan, blast injury has risen to a new level of importance and is recognized to be a major cause of injuries to the brain. However, an injury risk-function for microscopic, macroscopic, behavioral, and neurological deficits has yet to be defined. While operational blast injuries can be very complex and thus difficult to analyze, a simplified blast injury model would facilitate studies correlating biological outcomes with blast biomechanics to define tolerance criteria. Blast-induced traumatic brain injury (bTBI results from the translation of a shock wave in air, such as that produced by an IED, into a pressure wave within the skull-brain complex. Our blast injury methodology recapitulates this phenomenon in vitro, allowing for control of the injury biomechanics via a compressed-gas shock tube used in conjunction with a custom-designed, fluid-filled receiver that contains the living culture. The receiver converts the air shock wave into a fast-rising pressure transient with minimal reflections, mimicking the intracranial pressure history in blast. We have developed an organotypic hippocampal slice culture model that exhibits cell death when exposed to a 530  17.7 kPa peak overpressure with a 1.026 ± 0.017 ms duration and 190 ± 10.7 kPa-ms impulse in-air. We have also injured a simplified in vitro model of the blood-brain barrier, which exhibits disrupted integrity immediately following exposure to 581  10.0 kPa peak overpressure with a 1.067 ms ± 0.006 ms duration and 222 ± 6.9 kPa-ms impulse in-air. To better prevent and treat bTBI, both the initiating biomechanics and the ensuing pathobiology must be understood in greater detail. A well-characterized, in vitro model of bTBI, in conjunction with animal models, will be a powerful tool for developing strategies to mitigate the risks of bTBI.

Research on Effects of Blast Casting Vibration and Vibration Absorption of Presplitting Blasting in Open Cast Mine

Directory of Open Access Journals (Sweden)

Li Ma

2016-01-01

Full Text Available The impact energy produced by blast casting is able to break and cast rocks, yet the strong vibration effects caused at the same time would threaten the safety of mines. Based on the theory of Janbu’s Limit Equilibrium Method (LEM, pseudo-static method has been incorporated to analyze the influence of dynamic loads of blasting on slope stability. The horizontal loads produced by blast vibrations cause an increase in sliding forces, and this leads to a lower slope stability coefficient. When the tensile stresses of the two adjacent blast holes are greater than the tensile strength of rock mass, the radical oriented cracks are formed, which is the precondition for the formation of presplit face. Thus, the formula for calculating the blast hole spacing of presplit blasting can be obtained. Based on the analysis of the principles of vibration tester and vibration pick-up in detecting blast vibrations, a detection scheme of blast vibration is worked out by taking the blast area with precrack rear and non-precrack side of the detection object. The detection and research results of blast vibration show that presplit blasting can reduce the attenuation coefficient of stress wave by half, and the vibration absorption ratio could reach 50.2%; the impact of dynamic loads on the end-wall slope stability coefficient is 1.98%, which proves that presplit blasting plays an important role in shock absorption of blast casting.

Blasting Vibration Safety Criterion Analysis with Equivalent Elastic Boundary: Based on Accurate Loading Model

Directory of Open Access Journals (Sweden)

Qingwen Li

2015-01-01

Full Text Available In the tunnel and underground space engineering, the blasting wave will attenuate from shock wave to stress wave to elastic seismic wave in the host rock. Also, the host rock will form crushed zone, fractured zone, and elastic seismic zone under the blasting loading and waves. In this paper, an accurate mathematical dynamic loading model was built. And the crushed zone as well as fractured zone was considered as the blasting vibration source thus deducting the partial energy for cutting host rock. So this complicated dynamic problem of segmented differential blasting was regarded as an equivalent elastic boundary problem by taking advantage of Saint-Venant’s Theorem. At last, a 3D model in finite element software FLAC3D accepted the constitutive parameters, uniformly distributed mutative loading, and the cylindrical attenuation law to predict the velocity curves and effective tensile curves for calculating safety criterion formulas of surrounding rock and tunnel liner after verifying well with the in situ monitoring data.

Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of rho and Structure of the Circumburst Medium

Science.gov (United States)

Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.

2008-01-01

We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 medium.

Improvements to the Sandia CTH Hydro-Code to Support Blast Analysis and Protective Design of Military Vehicles

Science.gov (United States)

2014-04-15

used for advertising or product endorsement purposes. 6.0 REFERENCES [1] McGlaun, J., Thompson, S. and Elrick, M. “CTH: A Three-Dimensional Shock-Wave...Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles,” 7 th International LS-DYNA Users Conference, Detroit, MI 2002. [14

Hydrodynamic Simulations of Kepler's Supernova Remnant

Science.gov (United States)

Sullivan, Jessica; Blondin, John; Borkowski, Kazik; Reynolds, Stephen

2018-01-01

Kepler’s supernova remnant contains unusual features that strongly suggest an origin in a single-degenerate Type Ia explosion, including anisotropic circumstellar medium (CSM), a strong brightness gradient, and spatially varying expansion proper motions. We present 3Dhydrodynamic simulations to test a picture in which Kepler's progenitor binary emitted a strong asymmetric wind, densest in the orbital plane, while the system moved at high velocity through the ISM. We simulate the creation of the presupernova environment as well as the supernova blast wave, using the VH-1 grid-based hydrodynamics code. We first modeled an anisotropic wind to create an asymmetric bowshock around the progenitor, then the blast wave from thesupernova. The final simulation places both previous model pieces onto a single grid and allows the blast wave to expand into the bowshock. Models were completed on a Yin-Yang grids with matching angular resolutions. By manipulating parameters that control the asymmetry of the system, we attempted to find conditions that recreated the current state of Kepler. We analyzed these models by comparing images of Kepler from the Chandra X-ray Observatory to line-of-sight projections from the model results. We also present comparisons of simulated expansion velocities with recent observations of X-ray proper motions from Chandra images. We were able to produce models that contained similar features to those seen in Kepler. We find the greatest resemblance to Kepler images with a presupernova wind with an equator-to-pole density contrast of 3 and a moderately disk-like CSM at a 5° angle between equatorial plane and system motion.

Modelling and Simulation of Wave Loads

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Thoft-Christensen, Palle

velocity can be approximated by a Gaussian Markov process. Known approximate results for the first-passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on slender members of offshore structures is described. The wave elevation of the sea state is modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

Modelling and Simulation of Wave Loads

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Thoft-Christensen, Palle

1985-01-01

velocity can be approximated by a Gaussian Markov process. Known approximate results for the first passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on stender members of offshore structures is described . The wave elevation of the sea stateis modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

Study of blasting seismic effects of underground powerhouse of pumped storage project in granite condition

Science.gov (United States)

Wan, Sheng; Li, Hui

2018-03-01

Though the test of blasting vibration, the blasting seismic wave propagation laws in southern granite pumped storage power project are studied. Attenuation coefficient of seismic wave and factors coefficient are acquired by the method of least squares regression analysis according to Sadaovsky empirical formula, and the empirical formula of seismic wave is obtained. This paper mainly discusses on the test of blasting vibration and the procedure of calculation. Our practice might as well serve as a reference for similar projects to come.

Comparison of Some Blast Vibration Predictors for Blasting in Underground Drifts and Some Observations

Science.gov (United States)

Bhagwat, Vaibhab Pramod; Dey, Kaushik

2016-04-01

Drilling and blasting are the most economical excavation techniques in underground drifts driven through hard rock formation. Burn cut is the most popular drill pattern, used in this case, to achieve longer advance per blast round. The ground vibration generated due to the propagation of blast waves on the detonation of explosive during blasting is the principal cause for structural and rock damage. Thus, ground vibration is a point of concern for the blasting engineers. The ground vibration from a blast is measured using a seismograph placed at the blast monitoring station. The measured vibrations, in terms of peak particle velocity, are related to the maximum charge detonated at one instant and the distance of seismograph from the blast point. The ground vibrations from a number of blast rounds of varying charge/delay and distances are monitored. A number of scaling factors of these dependencies (viz. Distance and maximum charge/delay) have been proposed by different researchers, namely, square root, cube root, CMRI, Langefors and Kihlstrom, Ghosh-Daemon, Indian standard etc. Scaling factors of desired type are computed for all the measured blast rounds. Regression analysis is carried out between the scaling factors and peak particle velocities to establish the coefficients of the vibration predictor equation. Then, the developed predictor equation is used for designing the blast henceforth. Director General of Mine Safety, India, specified that ground vibrations from eight to ten blast rounds of varying charge/delay and distances should be monitored to develop a predictor equation; however, there is no guideline about the type of scaling factor to be used. Further to this, from the statistical point of view, a regression analysis on a small sample population cannot be accepted without the testing of hypothesis. To show the importance of the above, in this paper, seven scaling factors are considered for blast data set of a hard-rock underground drift using burn

Mathematical models of blast induced TBI: current status, challenges and prospects

Directory of Open Access Journals (Sweden)

Raj K Gupta

2013-05-01

Full Text Available Blast induced traumatic brain injury (TBI has become a signature wound of recent military activities and is the leading cause of death and long-term disability among U.S. soldiers. The current limited understanding of brain injury mechanisms impedes the development of protection, diagnostic and treatment strategies. We believe mathematical models of blast wave brain injury biomechanics and neurobiology, complemented with in vitro and in vivo experimental studies, will enable a better understanding of injury mechanisms and accelerate the development of both protective and treatment strategies. The goal of this paper is to review the current state of the art in mathematical and computational modeling of blast induced TBI, identify research gaps and recommend future developments. A brief overview of blast wave physics, injury biomechanics and the neurobiology of brain injury is used as a foundation for a more detailed discussion of multiscale mathematical models of primary biomechanics and secondary injury and repair mechanisms. The paper also presents a discussion of model development strategies, experimental approaches to generate benchmark data for model validation and potential applications of the model for prevention and protection against blast wave TBI.

Modeling of Combined Impact and Blast Loading on Reinforced Concrete Slabs

Directory of Open Access Journals (Sweden)

P. Del Linz

Full Text Available Abstract Explosive devices represent a significant threat to military and civilian structures. Specific design procedures have to be followed to account for this and ensure buildings will have the capacity to resist the imposed pressures. Shrapnel can also be produced during explosions and the resulting impacts can weaken the structure, reducing its capacity to resist the blast pressure wave and potentially causing failures to occur. Experiments were performed by the Defence Science and Technology Agency (DSTA of Singapore to study this combined loading phenomenon. Slabs were placed on the ground and loaded with approximately 9 kg TNT charges at a standoff distance of 2.1 m. Spherical steel ball bearings were used to reproduce the shrapnel loading. Loading and damage characteristics were recorded from the experiments. A finite element analysis (FEA model was then created which could simulate the effect of combined shrapnel impacts and blast pressure waves in reinforced concrete slabs, so that its results could be compared to experimental data from the blast tests. Quarter models of the experimental concrete slabs were built using LS-Dyna. Material models available in the software were employed to represent all the main components, taking into account projectile deformations. The penetration depth and damage areas measured were then compared to the experimental data and an analytical solution to validate the models.

Blast resistance behaviour of steel frame structrures

NARCIS (Netherlands)

Mediavilla Varas, J.; Soetens, F.

2010-01-01

The effect of a blast explosion on a typical steel frame building is investigated by means of computer simulations. The simulations help to identify possible hot spots that may lead to local or global failure. Since the blast energy is transferred to the structure by means of the façade, it is

Blast resistance behaviour of steel frame structures

NARCIS (Netherlands)

Varas, J.M.; Soetens, F.

2010-01-01

The effect of a blast explosion on a typical steel frame building is investigated by means of computer simulations. The simulations help to identify possible hot spots that may lead to local or global failure. The blast energy is transferred to the structure by means of the façade. In particular

Protection of the lung from blast overpressure by stress wave decouplers, buffer plates or sandwich panels.

Science.gov (United States)

Sedman, Andrew; Hepper, A

2018-03-19

This paper outlines aspects of UK Ministry of Defence's research and development of blast overpressure protection technologies appropriate for use in body armour, with the aim of both propagating new knowledge and updating existing information. Two simple models are introduced not only to focus the description of the mechanism by which the lungs can be protected, but also to provide a bridge between fields of research that may hold the key to further advances in protection technology and related body armour. Protection can be provided to the lungs by decoupling the stress wave transmission into the thorax by managing the blast energy imparted through the protection system. It is proposed that the utility of the existing 'simple decoupler' blast overpressure protection is reviewed in light of recent developments in the treatment of those sustaining both overpressure and fragment injuries. It is anticipated that further advances in protection technology may be generated by those working in other fields on the analogous technologies of 'buffer plates' and 'sandwich panels'. © Crown copyright (2018), Dstl. This material is licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gsi.gov.uk.

Computer simulation of driven Alfven waves

International Nuclear Information System (INIS)

Geary, J.L. Jr.

1986-01-01

The first particle simulation study of shear Alfven wave resonance heating is presented. Particle simulation codes self-consistently follow the time evolution of the individual and collective aspects of particle dynamics as well as wave dynamics in a fully nonlinear fashion. Alfven wave heating is a possible means of increasing the temperature of magnetized plasmas. A new particle simulation model was developed for this application that incorporates Darwin's formulation of the electromagnetic fields with a guiding center approximation for electron motion perpendicular to the ambient magnetic field. The implementation of this model and the examination of its theoretical and computational properties are presented. With this model, several cases of Alfven wave heating is examined in both uniform and nonuniform simulation systems in a two dimensional slab. For the inhomogeneous case studies, the kinetic Alfven wave develops in the vicinity of the shear Alfven resonance region

Simulation analyses of vibration tests on pile-group effects using blast-induced ground motions

International Nuclear Information System (INIS)

Takayuki Hashimoto; Kazushige Fujiwara; Katsuichirou Hijikata; Hideo Tanaka; Kohji Koyamada; Atsushi Suzuki; Osamu Kontani

2005-01-01

Extensive vibration tests have been performed on pile-supported structures at a large-scale mining site to promote better understanding of the dynamic behavior of pile-supported structures, especially pile-group effects. Two test structures were constructed in an excavated pit. One structure was supported on 25 tubular steel piles and the other on 4. The test pit was backfilled with sand of an appropriate grain size distribution to ensure good compaction. Ground motions induced by large-scale blasting operations were used as excitation forces for the tests. The 3D Finite Element Method (3D FEM)and a Genetic Algorithm (GA) were employed to identify the shear wave velocities and damping factors of the compacted sand, especially of the surface layer. A beam-interaction spring model was employed to simulate the test results of the piles and the pile-supported structures. The superstructure and pile foundation were modeled by a one-stick model comprising lumped masses and beam elements. The pile foundations were modeled just as they were, with lumped masses and beam elements to simulate the test results showing that, for the 25-pile structure, piles at different locations showed different responses. It was confirmed that the analysis methods employed were very useful for evaluating the nonlinear behavior of the soil-pile-structure system, even under severe ground motions. (authors)

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

Directory of Open Access Journals (Sweden)

Xiaoqiu Xu

2017-01-01

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

Observation and modeling of mixing-layer development in high-energy-density, blast-wave-driven shear flow

International Nuclear Information System (INIS)

Di Stefano, C. A.; Kuranz, C. C.; Klein, S. R.; Drake, R. P.; Malamud, G.; Henry de Frahan, M. T.; Johnsen, E.; Shimony, A.; Shvarts, D.; Smalyuk, V. A.; Martinez, D.

2014-01-01

In this work, we examine the hydrodynamics of high-energy-density (HED) shear flows. Experiments, consisting of two materials of differing density, use the OMEGA-60 laser to drive a blast wave at a pressure of ∼50 Mbar into one of the media, creating a shear flow in the resulting shocked system. The interface between the two materials is Kelvin-Helmholtz unstable, and a mixing layer of growing width develops due to the shear. To theoretically analyze the instability's behavior, we rely on two sources of information. First, the interface spectrum is well-characterized, which allows us to identify how the shock front and the subsequent shear in the post-shock flow interact with the interface. These observations provide direct evidence that vortex merger dominates the evolution of the interface structure. Second, simulations calibrated to the experiment allow us to estimate the time-dependent evolution of the deposition of vorticity at the interface. The overall result is that we are able to choose a hydrodynamic model for the system, and consequently examine how well the flow in this HED system corresponds to a classical hydrodynamic description

Shock wave interaction with turbulence: Pseudospectral simulations

International Nuclear Information System (INIS)

Buckingham, A.C.

1986-01-01

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

Novel method to dynamically load cells in 3D-gel culture for primary blast injury studies

Science.gov (United States)

Sory, David; Cepa-Areias, Anabela; Overby, Darryl; Proud, William; Institute of Shock Physics, Department of Bioengineering; Royal British Legion CentreBlast I Collaboration

2015-06-01

For at least a century explosive devices have been reported as one of the most important causes of injuries on battlefield in military conflicts as well as in terrorist attacks. Although significant experimental and modelling efforts have been focussed on blast injury at the organ or tissue level, few studies have investigated the mechanism of blast injury at the cellular level. This paper introduces an in vitro method compatible with living cells to examine the effects of high stress and short-duration pulses similar to those observed in blast waves. The experimental phase involved high strain rate axial compression of biological cylindrical specimens within a hermetically sealed sample holder made of a biocompatible polymer. Numerical simulations were performed in order to characterize the loading path within the sample and assess the loading conditions. A proof of concept is presented so as to establish a new window to address fundamental questions regarding primary blast injury at the cellular level. The Institute of Shock Physics acknowledges the support of AWE, Aldermaston, UK and Imperial College London. The Centre for Blast Injury Studies acknowledges the support of the Royal British Legion and Imperial College London.

In silico investigation of blast-induced intracranial fluid cavitation as it potentially leads to traumatic brain injury

Science.gov (United States)

Haniff, S.; Taylor, P. A.

2017-11-01

We conducted computational macroscale simulations predicting blast-induced intracranial fluid cavitation possibly leading to brain injury. To further understanding of this problem, we developed microscale models investigating the effects of blast-induced cavitation bubble collapse within white matter axonal fiber bundles of the brain. We model fiber tracks of myelinated axons whose diameters are statistically representative of white matter. Nodes of Ranvier are modeled as unmyelinated sections of axon. Extracellular matrix envelops the axon fiber bundle, and gray matter is placed adjacent to the bundle. Cavitation bubbles are initially placed assuming an intracranial wave has already produced them. Pressure pulses, of varied strengths, are applied to the upper boundary of the gray matter and propagate through the model, inducing bubble collapse. Simulations, conducted using the shock wave physics code CTH, predict an increase in pressure and von Mises stress in axons downstream of the bubbles after collapse. This appears to be the result of hydrodynamic jetting produced during bubble collapse. Interestingly, results predict axon cores suffer significantly lower shear stresses from proximal bubble collapse than does their myelin sheathing. Simulations also predict damage to myelin sheathing, which, if true, degrades axonal electrical transmissibility and general health of the white matter structures in the brain.

Rapid Monte Carlo Simulation of Gravitational Wave Galaxies

Science.gov (United States)

Breivik, Katelyn; Larson, Shane L.

2015-01-01

With the detection of gravitational waves on the horizon, astrophysical catalogs produced by gravitational wave observatories can be used to characterize the populations of sources and validate different galactic population models. Efforts to simulate gravitational wave catalogs and source populations generally focus on population synthesis models that require extensive time and computational power to produce a single simulated galaxy. Monte Carlo simulations of gravitational wave source populations can also be used to generate observation catalogs from the gravitational wave source population. Monte Carlo simulations have the advantes of flexibility and speed, enabling rapid galactic realizations as a function of galactic binary parameters with less time and compuational resources required. We present a Monte Carlo method for rapid galactic simulations of gravitational wave binary populations.

Simulation of Wave Overtopping of Maritime Structures in a Numerical Wave Flume

Directory of Open Access Journals (Sweden)

Tiago C. A. Oliveira

2012-01-01

Full Text Available A numerical wave flume based on the particle finite element method (PFEM is applied to simulate wave overtopping for impermeable maritime structures. An assessment of the performance and robustness of the numerical wave flume is carried out for two different cases comparing numerical results with experimental data. In the first case, a well-defined benchmark test of a simple low-crested structure overtopped by regular nonbreaking waves is presented, tested in the lab, and simulated in the numerical wave flume. In the second case, state-of-the-art physical experiments of a trapezoidal structure placed on a sloping beach overtopped by regular breaking waves are simulated in the numerical wave flume. For both cases, main overtopping events are well detected by the numerical wave flume. However, nonlinear processes controlling the tests proposed, such as nonlinear wave generation, energy losses along the wave propagation track, wave reflection, and overtopping events, are reproduced with more accuracy in the first case. Results indicate that a numerical wave flume based on the PFEM can be applied as an efficient tool to supplement physical models, semiempirical formulations, and other numerical techniques to deal with overtopping of maritime structures.

Minimization of Blast furnace Fuel Rate by Optimizing Burden and Gas Distribution

Energy Technology Data Exchange (ETDEWEB)

Dr. Chenn Zhou

2012-08-15

The goal of the research is to improve the competitive edge of steel mills by using the advanced CFD technology to optimize the gas and burden distributions inside a blast furnace for achieving the best gas utilization. A state-of-the-art 3-D CFD model has been developed for simulating the gas distribution inside a blast furnace at given burden conditions, burden distribution and blast parameters. The comprehensive 3-D CFD model has been validated by plant measurement data from an actual blast furnace. Validation of the sub-models is also achieved. The user friendly software package named Blast Furnace Shaft Simulator (BFSS) has been developed to simulate the blast furnace shaft process. The research has significant benefits to the steel industry with high productivity, low energy consumption, and improved environment.

Computer simulation of ultrasonic waves in solids

International Nuclear Information System (INIS)

Thibault, G.A.; Chaplin, K.

1992-01-01

A computer model that simulates the propagation of ultrasonic waves has been developed at AECL Research, Chalk River Laboratories. This program is called EWE, short for Elastic Wave Equations, the mathematics governing the propagation of ultrasonic waves. This report contains a brief summary of the use of ultrasonic waves in non-destructive testing techniques, a discussion of the EWE simulation code explaining the implementation of the equations and the types of output received from the model, and an example simulation showing the abilities of the model. (author). 2 refs., 2 figs

The determination of Fe, Mn and Ca in sintered iron and blast-furnace slag by X-ray fluorescent analyses of energy and wave dispersion-comparison of results

International Nuclear Information System (INIS)

Dworak, B.; Gajek, Sz.

1980-01-01

The results of sintered iron and of blast-furnace slag examination obtained by X-ray fluorescent analyses of energy and of wave dispersion are compared. They show that the methods are comparable for such elements as Ca and Fe, whereas for Mn (in sinter) the X-ray fluorescent analysis of wave dispersion is less precise. (author)

Gamma-ray burst afterglows as probes of environment and blast wave physics. II. The distribution of p and structure of the circumburst medium

NARCIS (Netherlands)

Starling, R.L.C.; van der Horst, A.J.; Rol, E.; Wijers, R.A.M.J.; Kouveliotou, C.; Wiersema, K.; Curran, P.A.; Weltevrede, P.

2008-01-01

We constrain blast wave parameters and the circumburst media of a subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral

Comprehensive Numerical Modeling of the Blast Furnace Ironmaking Process

Science.gov (United States)

Zhou, Chenn; Tang, Guangwu; Wang, Jichao; Fu, Dong; Okosun, Tyamo; Silaen, Armin; Wu, Bin

2016-05-01

Blast furnaces are counter-current chemical reactors, widely utilized in the ironmaking industry. Hot reduction gases injected from lower regions of the furnace ascend, reacting with the descending burden. Through this reaction process, iron ore is reduced into liquid iron that is tapped from the furnace hearth. Due to the extremely harsh environment inside the blast furnace, it is difficult to measure or observe internal phenomena during operation. Through the collaboration between steel companies and the Center for Innovation through Visualization and Simulation, multiple computational fluid dynamics (CFD) models have been developed to simulate the complex multiphase reacting flow in the three regions of the furnace, the shaft, the raceway, and the hearth. The models have been used effectively to troubleshoot and optimize blast furnace operations. In addition, the CFD models have been integrated with virtual reality. An interactive virtual blast furnace has been developed for training purpose. This paper summarizes the developments and applications of blast furnace CFD models and the virtual blast furnace.

Conversion of piston-driven shocks from powerful solar flares to blast wave shocks in the solar wind

International Nuclear Information System (INIS)

Pinter, S.

1990-01-01

It was suggested by Smart and Shea (1985) that the time of arrival of solar-flare-generated shock waves at any point in space may be predicted by assuming that they are first driven from the Sun after which they decay into blast shocks. Their study was extended by using the duration of the Type IV radio emission as a phenomenological symptom of the piston-driven phase of these shocks. Using a sample of 39 cases of combined Type II/Type IV observations from 1972 to 1982 solar flares, it was found that the average predicted times-of-arrival of these shocks to Earth (and elsewhere) deviate from the actual times by 1.40 hr with a standard deviation of 1.25 hr. On the average, a representative shock from this sample is emitted from a powerful flare with a velocity of 1,560 km sec -1 ; moves at a constant inertial velocity to a distance of 0.12 AU after which it begins to decelerate as a classical (Sedov-type) blast shock that is convected by the ambient solar wind as suggested by Smart and Shea; and arrives to Earth 45.8 hr after its initiation in the Sun. Shocks that appear to deviate from this phenomenological scenario by virtue of lack of detection on Earth are assumed to decay into fast mode MHD waves. (author). 7 figs., 1 tab., 53 refs

Blast overpressure after tire explosion: a fatal case.

Science.gov (United States)

Pomara, Cristoforo; D'Errico, Stefano; Riezzo, Irene; Perilli, Gabriela; Volpe, Umberto; Fineschi, Vittorio

2013-12-01

Fatal blast injuries are generally reported in literature as a consequence of the detonation of explosives in war settings. The pattern of lesion depends on the position of the victim in relation to the explosion, on whether the blast tracks through air or water, and whether it happens in the open air or within an enclosed space and the distance from the explosion. Tire explosion-related injuries are rarely reported in literature. This study presents a fatal case of blast overpressure due to the accidental explosion of a truck tire occurring in a tire repair shop. A multidisciplinary approach to the fatality involving forensic pathologists and engineers revealed that the accidental explosion, which caused a series of primary and tertiary blast wave injuries, was due to tire deterioration.

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

Science.gov (United States)

Groenig, Hans

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

Ocean Wave Simulation Based on Wind Field.

Directory of Open Access Journals (Sweden)

Zhongyi Li

Full Text Available Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

Primary Blast-Induced Changes in Akt and GSK3β Phosphorylation in Rat Hippocampus

Directory of Open Access Journals (Sweden)

Yushan Wang

2017-08-01

Full Text Available Traumatic brain injury (TBI due to blast from improvised explosive devices has been a leading cause of morbidity and mortality in recent conflicts in Iraq and Afghanistan. However, the mechanisms of primary blast-induced TBI are not well understood. The Akt signal transduction pathway has been implicated in various brain pathologies including TBI. In the present study, the effects of simulated primary blast waves on the phosphorylation status of Akt and its downstream effector kinase, glycogen synthase kinase 3β (GSK3β, in rat hippocampus, were investigated. Male Sprague-Dawley (SD rats (350–400 g were exposed to a single pulse shock wave (25 psi; ~7 ms duration and sacrificed 1 day, 1 week, or 6 weeks after exposure. Total and phosphorylated Akt, as well as phosphorylation of its downstream effector kinase GSK3β (at serine 9, were detected with western blot analysis and immunohistochemistry. Results showed that Akt phosphorylation at both serine 473 and threonine 308 was increased 1 day after blast on the ipsilateral side of the hippocampus, and this elevation persisted until at least 6 weeks postexposure. Similarly, phosphorylation of GSK3β at serine 9, which inhibits GSK3β activity, was also increased starting at 1 day and persisted until at least 6 weeks after primary blast on the ipsilateral side. In contrast, p-Akt was increased at 1 and 6 weeks on the contralateral side, while p-GSK3β was increased 1 day and 1 week after primary blast exposure. No significant changes in total protein levels of Akt and GSK were observed on either side of the hippocampus at any time points. Immunohistochemical results showed that increased p-Akt was mainly of neuronal origin in the CA1 region of the hippocampus and once phosphorylated, the majority was translocated to the dendritic and plasma membranes. Finally, electrophysiological data showed that evoked synaptic N-methyl-d-aspartate (NMDA receptor activity was

The importance of systemic response in the pathobiology of blast-induced neurotrauma

Directory of Open Access Journals (Sweden)

Ibolja eCernak

2010-12-01

Full Text Available Due to complex injurious environment where multiple blast effects interact with the body, parallel blast-induced neurotrauma is a unique clinical entity induced by systemic, local, and cerebral responses. Activation of autonomous nervous system; sudden pressure-increase in vital organs such as lungs and liver; and activation of neuroendocrine-immune system are among the most important mechanisms that contribute significantly to molecular changes and cascading injury mechanisms in the brain. It has been hypothesized that vagally mediated cerebral effects play a vital role in the early response to blast: this assumption has been supported by experiments where bilateral vagotomy mitigated bradycardia, hypotension, and apnea, and also prevented excessive metabolic alterations in the brain of animals exposed to blast. Clinical experience suggests specific blast-body-nervous system interactions such as 1 direct interaction with the head either through direct passage of the blast wave through the skull or by causing acceleration and/or rotation of the head; and 2 via hydraulic interaction, when the blast overpressure compresses the abdomen and chest, and transfers its kinetic energy to the body’s fluid phase, initiating oscillating waves that traverse the body and reach the brain. Accumulating evidence suggests that inflammation plays important role in the pathogenesis of long-term neurological deficits due to blast. These include memory decline, motor function and balance impairments, and behavioral alterations, among others. Experiments using rigid body- or head protection in animals subjected to blast showed that head protection failed to prevent inflammation in the brain or reduce neurological deficits, whereas body protection was successful in alleviating the blast-induced functional and morphological impairments in the brain.

Blast-induced electromagnetic fields in the brain from bone piezoelectricity.

Science.gov (United States)

Lee, Ka Yan Karen; Nyein, Michelle K; Moore, David F; Joannopoulos, J D; Socrate, Simona; Imholt, Timothy; Radovitzky, Raul; Johnson, Steven G

2011-01-01

In this paper, we show that bone piezoelectricity-a phenomenon in which bone polarizes electrically in response to an applied mechanical stress and produces a short-range electric field-may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects. We compute the induced charge density in the skull from stress data on the skull from a finite-element full-head model simulation of a typical IED-scale blast wave incident on an unhelmeted human head as well as a human head protected by a kevlar helmet, and estimate the resulting electric fields in the brain in both cases to be on the order of 10 V/m in millisecond pulses. These fields are more than 10 times stronger than the IEEE safety guidelines for controlled environments (IEEE Standards Coordinating Committee 28, 2002) and comparable in strength and timescale to fields from repetitive Transcranial Magnetic Stimulation (rTMS) that are designed to induce neurological effects (Wagner et al., 2006a). They can be easily measured by RF antennas, and may provide the means to design a diagnostic tool that records a quantitative measure of the head's exposure to blast insult. Copyright © 2010 Elsevier Inc. All rights reserved.

A Software Framework for Blast Event Simulation

National Research Council Canada - National Science Library

Swensen, D. A; Denison, M. K; Guilkey, James; Harman, Todd; Goetz, Richard

2006-01-01

.... The BCF will provide a virtual test-bed where disparate computational models can seamlessly interact with one another to provide a unified modeling solution for blast-vehicle-occupant scenarios...

Experimental Study of Bilinear Initiating System Based on Hard Rock Pile Blasting

Directory of Open Access Journals (Sweden)

Yusong Miao

2017-01-01

Full Text Available It is difficult to use industrial explosives to excavate hard rock and achieve suitable blasting effect due to the low energy utilization rate resulting in large rocks and short blasting footage. Thus, improving the utilization ratio of the explosive energy is important. In this study, a novel bilinear initiation system based on hard rock blasting was proposed to improve the blasting effects. Furthermore, on the basis of the detonation wave collision theory, frontal collision, oblique reflection, and Mach reflection during detonation wave propagation were studied. The results show that the maximum detonation pressure at the Mach reflection point where the incident angle is 46.9° is three times larger than the value of the explosive complete detonation. Then, in order to analyze the crack propagation in different initiation forms, a rock fracture test slot was designed, and the results show that bilinear initiating system can change the energy distribution of explosives. Finally, field experiment was implemented at the hard rock pile blasting engineering, and experimental results show that the present system possesses high explosive energy utilization ratio and low rock fragments size. The results of this study can be used to improve the efficiency in hard rock blasting.

2D RADIATION-HYDRODYNAMIC SIMULATIONS OF SUPERNOVA SHOCK BREAKOUT IN BIPOLAR EXPLOSIONS OF A BLUE SUPERGIANT PROGENITOR

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Akihiro; Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, 606-8502 (Japan); Shigeyama, Toshikazu [Research Center for the Early Universe, School of Science, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 (Japan)

2016-07-10

A two-dimensional special relativistic radiation-hydrodynamics code is developed and applied to numerical simulations of supernova shock breakout in bipolar explosions of a blue supergiant. Our calculations successfully simulate the dynamical evolution of a blast wave in the star and its emergence from the surface. Results of the model with spherical energy deposition show a good agreement with previous simulations. Furthermore, we calculate several models with bipolar energy deposition and compare their results with the spherically symmetric model. The bolometric light curves of the shock breakout emission are calculated by a ray-tracing method. Our radiation-hydrodynamic models indicate that the early part of the shock breakout emission can be used to probe the geometry of the blast wave produced as a result of the gravitational collapse of the iron core.

Integration of Tuyere, Raceway and Shaft Models for Predicting Blast Furnace Process

Science.gov (United States)

Fu, Dong; Tang, Guangwu; Zhao, Yongfu; D'Alessio, John; Zhou, Chenn Q.

2018-06-01

A novel modeling strategy is presented for simulating the blast furnace iron making process. Such physical and chemical phenomena are taking place across a wide range of length and time scales, and three models are developed to simulate different regions of the blast furnace, i.e., the tuyere model, the raceway model and the shaft model. This paper focuses on the integration of the three models to predict the entire blast furnace process. Mapping output and input between models and an iterative scheme are developed to establish communications between models. The effects of tuyere operation and burden distribution on blast furnace fuel efficiency are investigated numerically. The integration of different models provides a way to realistically simulate the blast furnace by improving the modeling resolution on local phenomena and minimizing the model assumptions.

Blast Impact Prediction Studies at Ghana Manganese Company ...

African Journals Online (AJOL)

Michael

2015-06-01

Jun 1, 2015 ... Keywords: Blast impact, Environment, Prediction, Regulatory threshold. 1 Introduction ... Noise is an environmental nuisance. .... explosion energy released into the ground generates vibration waves within the rock. Several.

Large eddy simulation of breaking waves

DEFF Research Database (Denmark)

Christensen, Erik Damgaard; Deigaard, Rolf

2001-01-01

A numerical model is used to simulate wave breaking, the large scale water motions and turbulence induced by the breaking process. The model consists of a free surface model using the surface markers method combined with a three-dimensional model that solves the flow equations. The turbulence....... The incoming waves are specified by a flux boundary condition. The waves are approaching in the shore-normal direction and are breaking on a plane, constant slope beach. The first few wave periods are simulated by a two-dimensional model in the vertical plane normal to the beach line. The model describes...... the steepening and the overturning of the wave. At a given instant, the model domain is extended to three dimensions, and the two-dimensional flow field develops spontaneously three-dimensional flow features with turbulent eddies. After a few wave periods, stationary (periodic) conditions are achieved...

Simulation Engine for Fluid Solid Interaction Problems and its Application to the Modelling of Air Blast Hazards in Block Cave Mining.

Science.gov (United States)

Galindo Torres, S. A.; Scheuermann, A.; Ruest, M.

2016-12-01

Air blasts that may occur in a block caving mining operation represent a significant hazard for personnel as well as to mining infrastructure. Uncontrolled caving of a large volume of broken rock into a mine void causes compression of the air within, forcing it to flow at high velocities into connecting tunnels such as extraction points beneath the cave or observation points intersecting the cave. This high velocity flow of air can cause injury to personnel and significant damage to equipment. In this presentation, we introduce a simulation engine for the air blast problem. The solid material is modelled using the Discrete Element Method (DEM) and the fluid (air) is modelled using the Lattice Boltzmann Method (LBM). The combined DEM-LBM approach has been introduced by our group at the University of Queensland[1]. LBM allows us to introduce an appropriate equation of state for the air that simulates compressibility as a function of the speed of sound. Validation examples are presented to justify the use of this tool for an air blasting situation. A section view of one simulation is provided in Fig 1. An investigation into the risk of developing air pockets as a function of fragment size distribution is also conducted and described. The fragment size distribution can be assessed during mining and the risk of air pockets forming (and consequently of air blast occurring) can be deduced and mitigation measures put in place. The effect of other key variables that can be determined from geotechnical investigations, such as fracture frequency, are also systematically explored. It is expected that the results of this study can elucidate key features of the air blasting phenomenon in order to formulate safer mining protocols. references 1. Galindo-Torres, S.A., A coupled Discrete Element Lattice Boltzmann Method for the simulation of fluid-solid interaction with particles of general shapes. Computer Methods in Applied Mechanics and Engineering, 2013. 265(0): p. 107-119.

A multiphysics-viscoplastic cap model for simulating blast response of cemented tailings backfill

Directory of Open Access Journals (Sweden)

Gongda Lu

2017-06-01

Full Text Available Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill, an evolutive porous medium used in underground mine cavities, very few efforts have been made to improve the knowledge on its response under sudden dynamic loading during the curing process. In fact, there is a great need for such information given that cemented backfill structures are often subjected to blast loadings due to mine exploitations. In this study, a coupled thermo-hydro-mechanical-chemical (THMC-viscoplastic cap model is developed to describe the behavior of cementing mine backfill material under blast loading. A THMC model for cemented backfill is adopted to evaluate its behavior and evolution of its properties in curing processes with coupled thermal, hydraulic, mechanical and chemical factors. Then, the model is coupled to a Perzyna type of viscoplastic model with a modified smooth surface cap envelope and a variable bulk modulus, in order to reasonably capture the nonlinear and rate-dependent behaviors of the cemented tailings backfill under blast loading. All of the parameters required for the variable-modulus viscoplastic cap model were obtained by applying the THMC model to reproducing evolution of cemented paste backfill (CPB properties in the curing process. Thus, the behavior of hydrating cemented backfill under high-rate impacts can be evaluated under any curing time of concern. The validation results of the proposed model indicate a good agreement between the experimental and the simulated results. The authors believe that the proposed model will contribute to a better understanding of the performance of hydrating cemented backfill under blasting, and also to practical risk management of backfill structures associated with such a dynamic condition.

Fragment Size Distribution of Blasted Rock Mass

Science.gov (United States)

Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

2017-12-01

Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

2D full wave simulation on electromagnetic wave propagation in toroidal plasma

International Nuclear Information System (INIS)

Hojo, Hitoshi; Uruta, Go; Nakayama, Kazunori; Mase, Atsushi

2002-01-01

Global full-wave simulation on electromagnetic wave propagation in toroidal plasma with an external magnetic field imaging a tokamak configuration is performed in two dimensions. The temporal behavior of an electromagnetic wave launched into plasma from a wave-guiding region is obtained. (author)

DRI internal Wave Simulations

National Research Council Canada - National Science Library

Reynolds, Stephen A; Levine, Murray D

2005-01-01

.... A processing module is developed that takes profile estimates as input and uses numerically simulated linear internal wave displacements to create two-dimensional range-dependent sound speed fields...

An ultra-fast fiber optic pressure sensor for blast event measurements

International Nuclear Information System (INIS)

Wu, Nan; Tian, Ye; Wang, Xingwei; Zou, Xiaotian; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie

2012-01-01

Soldiers who are exposed to explosions are at risk of suffering traumatic brain injury (TBI). Since the causal relationship between a blast and TBI is poorly understood, it is critical to have sensors that can accurately quantify the blast dynamics and resulting wave propagation through a helmet and skull that are imparted onto and inside the brain. To help quantify the cause of TBI, it is important to record transient pressure data during a blast event. However, very few sensors feature the capabilities of tracking the dynamic pressure transients due to the rapid change of the pressure during blast events, while not interfering with the physical material layers or wave propagation. In order to measure the pressure transients efficiently, a pressure sensor should have a high resonant frequency and a high spatial resolution. This paper describes an ultra-fast fiber optic pressure sensor based on the Fabry–Perot principle for the application of measuring the rapid pressure changes in a blast event. A shock tube experiment performed in US Army Natick Soldier Research, Development and Engineering Center has demonstrated that the resonant frequency of the sensor is 4.12 MHz, which is relatively close to the designed theoretical value of 4.113 MHz. Moreover, the experiment illustrated that the sensor has a rise time of 120 ns, which demonstrates that the sensor is capable of observing the dynamics of the pressure transient during a blast event. (paper)

Discrete element simulation of charging and mixed layer formation in the ironmaking blast furnace

Science.gov (United States)

Mitra, Tamoghna; Saxén, Henrik

2016-11-01

The burden distribution in the ironmaking blast furnace plays an important role for the operation as it affects the gas flow distribution, heat and mass transfer, and chemical reactions in the shaft. This work studies certain aspects of burden distribution by small-scale experiments and numerical simulation by the discrete element method (DEM). Particular attention is focused on the complex layer-formation process and the problems associated with estimating the burden layer distribution by burden profile measurements. The formation of mixed layers is studied, and a computational method for estimating the extent of the mixed layer, as well as its voidage, is proposed and applied on the results of the DEM simulations. In studying a charging program and its resulting burden distribution, the mixed layers of coke and pellets were found to show lower voidage than the individual burden layers. The dynamic evolution of the mixed layer during the charging process is also analyzed. The results of the study can be used to gain deeper insight into the complex charging process of the blast furnace, which is useful in the design of new charging programs and for mathematical models that do not consider the full behavior of the particles in the burden layers.

On firework blasts and qualitative parameter dependency.

Science.gov (United States)

Zohdi, T I

2016-01-01

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given.

Gas explosion characterization, wave propagation (small scale experiments)

International Nuclear Information System (INIS)

Larsen, G.C.

1985-08-01

A number of experiments have been performed with blast waves arising from the ignition of homogeneous and well defined mixtures of methane, oxygen and nitrogen, contained within spherical balloons with controlled initial dimensions. The pressure characteristics has been studied for blast waves with and without influence from reflected waves. The influence of obstacles in the flow field has also been treated. Both configuration with one box and two closely spaced boxes have been considered, and a wave-wave interaction phenomenon was observed in the case of closely spaced obstacles. Moreover reflection coefficients have been established and some pressure variations over the surfaces have been observed. An acoustic appriximation has been used to model the blast wave originating from an expanding sphere. It has been demonstrated, that the generated pressure pulse is very sensitive to the expansion rate. Calculated and measured data have been compared, and a reasonable agreement has been found. (author)

A Model to Simulate Titanium Behavior in the Iron Blast Furnace Hearth

Science.gov (United States)

Guo, Bao-Yu; Zulli, Paul; Maldonado, Daniel; Yu, Ai-Bing

2010-08-01

The erosion of hearth refractory is a major limitation to the campaign life of a blast furnace. Titanium from titania addition in the burden or tuyere injection can react with carbon and nitrogen in molten pig iron to form titanium carbonitride, giving the so-called titanium-rich scaffold or buildup on the hearth surface, to protect the hearth from subsequent erosion. In the current article, a mathematical model based on computational fluid dynamics is proposed to simulate the behavior of solid particles in the liquid iron. The model considers the fluid/solid particle flow through a packed bed, conjugated heat transfer, species transport, and thermodynamic of key chemical reactions. A region of high solid concentration is predicted at the hearth bottom surface. Regions of solid formation and dissolution can be identified, which depend on the local temperature and chemical equilibrium. The sensitivity to the key model parameters for the solid phase is analyzed. The model provides an insight into the fundamental mechanism of solid particle formation, and it may form a basic model for subsequent development to study the formation of titanium scaffold in the blast furnace hearth.

Blast-Resistant Improvement of Sandwich Armor Structure with Aluminum Foam Composite

OpenAIRE

Yang, Shu; Qi, Chang

2013-01-01

Sandwich armor structures with aluminum foam can be utilized to protect a military vehicle from harmful blast load such as a landmine explosion. In this paper, a system-level dynamic finite element model is developed to simulate the blast event and to evaluate the blast-resistant performance of the sandwich armor structure. It is found that a sandwich armor structure with only aluminum foam is capable of mitigating crew injuries under a moderate blast load. However, a severe blast load causes...

2D full-wave simulation of waves in space and tokamak plasmas

Directory of Open Access Journals (Sweden)

Kim Eun-Hwa

2017-01-01

Full Text Available Simulation results using a 2D full-wave code (FW2D for space and NSTX fusion plasmas are presented. The FW2D code solves the cold plasma wave equations using the finite element method. The wave code has been successfully applied to describe low frequency waves in planetary magnetospheres (i.e., dipole geometry and the results include generation and propagation of externally driven ultra-low frequency waves via mode conversion at Mercury and mode coupling, refraction and reflection of internally driven field-aligned propagating left-handed electromagnetic ion cyclotron (EMIC waves at Earth. In this paper, global structure of linearly polarized EMIC waves is examined and the result shows such resonant wave modes can be localized near the equatorial plane. We also adopt the FW2D code to tokamak geometry and examine radio frequency (RF waves in the scape-off layer (SOL of tokamaks. By adopting the rectangular and limiter boundary, we compare the results with existing AORSA simulations. The FW2D code results for the high harmonic fast wave heating case on NSTX with a rectangular vessel boundary shows excellent agreement with the AORSA code.

2D full-wave simulation of waves in space and tokamak plasmas

Science.gov (United States)

Kim, Eun-Hwa; Bertelli, Nicola; Johnson, Jay; Valeo, Ernest; Hosea, Joel

2017-10-01

Simulation results using a 2D full-wave code (FW2D) for space and NSTX fusion plasmas are presented. The FW2D code solves the cold plasma wave equations using the finite element method. The wave code has been successfully applied to describe low frequency waves in planetary magnetospheres (i.e., dipole geometry) and the results include generation and propagation of externally driven ultra-low frequency waves via mode conversion at Mercury and mode coupling, refraction and reflection of internally driven field-aligned propagating left-handed electromagnetic ion cyclotron (EMIC) waves at Earth. In this paper, global structure of linearly polarized EMIC waves is examined and the result shows such resonant wave modes can be localized near the equatorial plane. We also adopt the FW2D code to tokamak geometry and examine radio frequency (RF) waves in the scape-off layer (SOL) of tokamaks. By adopting the rectangular and limiter boundary, we compare the results with existing AORSA simulations. The FW2D code results for the high harmonic fast wave heating case on NSTX with a rectangular vessel boundary shows excellent agreement with the AORSA code.

Transition to turbulence and effect of initial conditions on three-dimensional compressible mixing in planar blast-wave-driven systems

International Nuclear Information System (INIS)

Miles, A.R.; Blue, B.; Edwards, M.J.; Greenough, J.A.; Hansen, J.F.; Robey, H.F.; Drake, R.P.; Kuranz, C.; Leibrandt, D.R.

2005-01-01

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional (3D) numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pretransition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernovae are discussed

Numerical Simulation of 3-D Wave Crests

Institute of Scientific and Technical Information of China (English)

YU Dingyong; ZHANG Hanyuan

2003-01-01

A clear definition of 3-D wave crest and a description of the procedures to detect the boundary of wave crest are presented in the paper. By using random wave theory and directional wave spectrum, a MATLAB-platformed program is designed to simulate random wave crests for various directional spectral conditions in deep water. Statistics of wave crests with different directional spreading parameters and different directional functions are obtained and discussed.

Advanced computational simulations of water waves interacting with wave energy converters

Science.gov (United States)

Pathak, Ashish; Freniere, Cole; Raessi, Mehdi

2017-03-01

Wave energy converter (WEC) devices harness the renewable ocean wave energy and convert it into useful forms of energy, e.g. mechanical or electrical. This paper presents an advanced 3D computational framework to study the interaction between water waves and WEC devices. The computational tool solves the full Navier-Stokes equations and considers all important effects impacting the device performance. To enable large-scale simulations in fast turnaround times, the computational solver was developed in an MPI parallel framework. A fast multigrid preconditioned solver is introduced to solve the computationally expensive pressure Poisson equation. The computational solver was applied to two surface-piercing WEC geometries: bottom-hinged cylinder and flap. Their numerically simulated response was validated against experimental data. Additional simulations were conducted to investigate the applicability of Froude scaling in predicting full-scale WEC response from the model experiments.

Bomb blast mass casualty incidents: initial triage and management of injuries.

Science.gov (United States)

Goh, S H

2009-01-01

Bomb blast injuries are no longer confined to battlefields. With the ever present threat of terrorism, we should always be prepared for bomb blasts. Bomb blast injuries tend to affect air-containing organs more, as the blast wave tends to exert a shearing force on air-tissue interfaces. Commonly-injured organs include the tympanic membranes, the sinuses, the lungs and the bowel. Of these, blast lung injury is the most challenging to treat. The clinical picture is a mix of acute respiratory distress syndrome and air embolism, and the institution of positive pressure ventilation in the presence of low venous pressures could cause systemic arterial air embolism. The presence of a tympanic membrane perforation is not a reliable indicator of the presence of a blast injury in the other air-containing organs elsewhere. Radiological imaging of the head, chest and abdomen help with the early identification of blast lung injury, head injury, abdominal injury, eye and sinus injuries, as well as any penetration by foreign bodies. In addition, it must be borne in mind that bomb blasts could also be used to disperse radiological and chemical agents.

Effects of low-level blast exposure on the nervous system: Is there really a controversy?

Directory of Open Access Journals (Sweden)

Gregory A Elder

2014-12-01

Full Text Available High-pressure blast waves can cause extensive CNS injury in humans. However, in combat settings such as Iraq and Afghanistan, lower level exposures associated with mild TBI (mTBI or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD. We describe how TBI is defined in humans and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in humans is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments a condition of low-level blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet animal studies show that low-level blast pressure waves are transmitted to the brain. In brain low-level blast exposures cause behavioral, biochemical, pathological and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system.

Advanced radiometric and interferometric milimeter-wave scene simulations

Science.gov (United States)

Hauss, B. I.; Moffa, P. J.; Steele, W. G.; Agravante, H.; Davidheiser, R.; Samec, T.; Young, S. K.

1993-01-01

Smart munitions and weapons utilize various imaging sensors (including passive IR, active and passive millimeter-wave, and visible wavebands) to detect/identify targets at short standoff ranges and in varied terrain backgrounds. In order to design and evaluate these sensors under a variety of conditions, a high-fidelity scene simulation capability is necessary. Such a capability for passive millimeter-wave scene simulation exists at TRW. TRW's Advanced Radiometric Millimeter-Wave Scene Simulation (ARMSS) code is a rigorous, benchmarked, end-to-end passive millimeter-wave scene simulation code for interpreting millimeter-wave data, establishing scene signatures and evaluating sensor performance. In passive millimeter-wave imaging, resolution is limited due to wavelength and aperture size. Where high resolution is required, the utility of passive millimeter-wave imaging is confined to short ranges. Recent developments in interferometry have made possible high resolution applications on military platforms. Interferometry or synthetic aperture radiometry allows the creation of a high resolution image with a sparsely filled aperture. Borrowing from research work in radio astronomy, we have developed and tested at TRW scene reconstruction algorithms that allow the recovery of the scene from a relatively small number of spatial frequency components. In this paper, the TRW modeling capability is described and numerical results are presented.

Blasting in hot zone - a case study

Energy Technology Data Exchange (ETDEWEB)

Nabiullah, B.M.P.; Pingua, J.; Dhar, B.B. [Central Mining Research Institute, Dhanbad (India)

1997-12-31

A significant quantity of coking coal reserves in the country are under fire particularly in Jharia coalfield. To control the fire and prevent loss of coal, an opencast mining method is adopted. The main problem with these opencast mines is drilling in hot strata and selection of suitable explosives and blasting in the fire zone. Trial blasts were conducted at two open cast mines. The problem was tackled by quenching the hot blast holes with water. Temperature of blast holes were recorded soon after drilling, after quenching with water and just before charging with explosives. The rise in temperature of charged explosives with time was also recorded until blasting. The thermal behaviour of commercially available explosives (including slurry, emulsion, ANFO and detonating cord) was investigated in laboratory and field simulated conditions. Emulsion, slurry compositions and detonating cord were found safe to use in hot holes up to 120{degree}C for duration of two hours. This paper describes the blasting practices adopted in the fire zones. 4 refs., 6 figs., 8 tabs.

Heat waves over Central Europe in regional climate model simulations

Science.gov (United States)

Lhotka, Ondřej; Kyselý, Jan

2014-05-01

Regional climate models (RCMs) have become a powerful tool for exploring impacts of global climate change on a regional scale. The aim of the study is to evaluate the capability of RCMs to reproduce characteristics of major heat waves over Central Europe in their simulations of the recent climate (1961-2000), with a focus on the most severe and longest Central European heat wave that occurred in 1994. We analyzed 7 RCM simulations with a high resolution (0.22°) from the ENSEMBLES project, driven by the ERA-40 reanalysis. In observed data (the E-OBS 9.0 dataset), heat waves were defined on the basis of deviations of daily maximum temperature (Tmax) from the 95% quantile of summer Tmax distribution in grid points over Central Europe. The same methodology was applied in the RCM simulations; we used corresponding 95% quantiles (calculated for each RCM and grid point) in order to remove the bias of modelled Tmax. While climatological characteristics of heat waves are reproduced reasonably well in the RCM ensemble, we found major deficiencies in simulating heat waves in individual years. For example, METNOHIRHAM simulated very severe heat waves in 1996, when no heat wave was observed. Focusing on the major 1994 heat wave, considerable differences in simulated temperature patterns were found among the RCMs. The differences in the temperature patterns were clearly linked to the simulated amount of precipitation during this event. The 1994 heat wave was almost absent in all RCMs that did not capture the observed precipitation deficit, while it was by far most pronounced in KNMI-RACMO that simulated virtually no precipitation over Central Europe during the 15-day period of the heat wave. By contrast to precipitation, values of evaporative fraction in the RCMs were not linked to severity of the simulated 1994 heat wave. This suggests a possible major contribution of other factors such as cloud cover and associated downward shortwave radiation. Therefore, a more detailed

Investigation on seismic signals for blasting in quarries

Czech Academy of Sciences Publication Activity Database

Pandula, B.; Kondela, J.; Holub, Karel

2012-01-01

Roč. 19, č. 1 (2012), s. 41-59 ISSN 1803-1447 Institutional support: RVO:68145535 Keywords : blasting operations * seismic safety * seismic waves Subject RIV: DC - Siesmology, Volcanology, Earth Structure http://www.caag.cz/egrse/2012-1/04_pandula-r.pdf

Calculation of driling and blasting parameters in blasting performance

OpenAIRE

Dambov, Risto; Karanakova Stefanovska, Radmila; Dambov, Ilija

2015-01-01

In all mining technology drilling and blasting parameters and works are one of the main production processes at each mine. The parameters of drilling and blasting and explosives consumption per ton of blasting mass are define economic indicators of any blasting no matter for what purpose and where mining is performed. The calculation of rock blasting should always have in mind that the methodology of calculation of all drilling and blasting parameters in blasting performance are performed for...

Oscillations in the wake of a flare blast wave

Science.gov (United States)

Tothova, D.; Innes, D. E.; Stenborg, G.

2011-04-01

Context. Oscillations of coronal loops in the Sun have been reported in both imaging and spectral observations at the onset of flares. Images reveal transverse oscillations, whereas spectra detect line-of-sight velocity or Doppler-shift oscillations. The Doppler-shift oscillations are commonly interpreted as longitudinal modes. Aims: Our aim is to investigate the relationship between loop dynamics and flows seen in TRACE 195 Å images and Doppler shifts observed by SUMER in Si iii 1113.2 Å and FeXIX 1118.1 Å at the time of a C.8-class limb flare and an associated CME. Methods: We carefully co-aligned the sequence of TRACE 195 Å images to structures seen in the SUMER Si iii, CaX, and FeXIX emission lines. Additionally, Hα observations of a lifting prominence associated with the flare and the coronal mass ejection (CME) are available in three bands around 6563.3 Å. They give constraints on the timing and geometry. Results: Large-scale Doppler-shift oscillations in FeXIX and transverse oscillations in intensity images were observed over a large region of the corona after the passage of a wide bright extreme-ultraviolet (EUV) disturbance, which suggests ionization, heating, and acceleration of hot plasma in the wake of a blast wave. The online movie associated to Fig. 2 is available at http://www.aanda.org and at http://www.mps.mpg.de/data/outgoing/tothova/movie.gif

Relationship between changes in the cochlear blood flow and disorder of hearing function induced by blast injury in guinea pigs.

Science.gov (United States)

Chen, Wei; Wang, Jianmin; Chen, Jing; Chen, Jichuan; Chen, Zhiqiang

2013-01-01

The auditory system is the most susceptible to damages from blast waves. Blast injuries always lead to varying degrees of hearing impairment. Although a disorder of the cochlear blood flow (CoBF) has been considered to be related to many pathological processes of the auditory system and to contribute to various types of hearing loss, changes in the CoBF induced by blast waves and the relationship between such changes and hearing impairment are undefined. To observe the changes in the cochlear microcirculation after exposure to an explosion blast, investigate the relationship between changes in the CoBF and hearing impairment and subsequently explore the mechanism responsible for the changes in the CoBF, we detected the perfusion of the cochlear microcirculation and hearing threshold shift after exposure to an explosion blast. Then, an N-nitro-L-arginine-methyl ester (L-NAME, NO synthase inhibitor) solution and artificial perilymph were applied to the round window (RW) of the cochlea before the blast exposure, followed by an evaluation of the CoBF and hearing function. The results indicated that the changes in the CoBF were correlated to the strength of the blast wave. The cochlear blood flow significantly increased when the peak value of the blast overpressure was greater than approximately 45 kPa, and there was no significant change in the cochlear blood flow when the peak value of the blast overpressure was less than approximately 35 kPa. Following local administration of the NO synthase inhibitor L-NAME, the increase in the CoBF induced by the blast was inhibited, and this reduction was significantly associated with the hearing threshold.

Analysis of Measured and Simulated Supraglottal Acoustic Waves.

Science.gov (United States)

Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A

2016-09-01

To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Experimental Study of the Effect of Water Mist Location On Blast Overpressure Attenuation in A Shock Tube

Science.gov (United States)

Mataradze, Edgar; Chikhradze, Nikoloz; Bochorishvili, Nika; Akhvlediani, Irakli; Tatishvili, Dimitri

2017-12-01

Explosion protection technologies are based on the formation of a shock wave mitigation barrier between the protection site and the explosion site. Contemporary protective systems use water mist as an extinguishing barrier. To achieve high effectiveness of the protective system, proper selection of water mist characteristics is important. The main factors defining shock wave attenuation in water mist include droplet size distribution, water concentration in the mist, droplet velocity and geometric properties of mist. This paper examines the process of attenuation of shock waves in mist with droplets ranging from 25 to 400 microns under different conditions of water mist location. Experiments were conducted at the Mining Institute with the use of a shock tube to study the processes of explosion suppression by a water mist barrier. The shock tube consists of a blast chamber, a tube, a system for the dosed supply of water, sensors, data recording equipment, and a process control module. Shock wave overpressure reduction coefficient was studied in the shock tube under two different locations of water mist: a) when water mist is created in direct contact with blast chamber and b) the blast chamber and the mist are separated by air space. It is established that in conditions when the air space distance between the blast chamber and the mist is 1 meter, overpressure reduction coefficient is 1.5-1.6 times higher than in conditions when water mist is created in direct contact with blast chamber.

Numerical analysis of blast flow-field of baffle type muzzle brake

Energy Technology Data Exchange (ETDEWEB)

Kim, D.H. [Graduate School, Chungnam National University, Taejon (Korea); Ko, S. [Chungnam National University, Taejon (Korea)

1998-11-01

A three-dimensional unsteady, inviscid blast flow-field of a baffle type muzzle brake has been simulated by solving the Euler equation. The blast flow-field includes the effect of the free air blast, precursor blast flow and the propellant blast gas flow. Chimera grid scheme was used to generate 9 multi-block volume grids for the complex geometry. The evolution of the blast flow-field is presented by showing the contours of pressure, density and Mach number for certain time step. The comparison of the calculated and measured peak pressures on the surfaces of the muzzle brake is also presented. (author). 4 refs., 5 figs., 1 tab.

Simulation of the collapse and dissipation of Langmuir wave packets

International Nuclear Information System (INIS)

Newman, D.L.; Winglee, R.M.; Robinson, P.A.; Glanz, J.; Goldman, M.V.

1990-01-01

The collapse of isolated Langmuir wave packets is studied numerically in two dimensions using both particle-in-cell (PIC) simulations and by integrating the Zakharov partial differential equations (PDE's). The initial state consists of a localized Langmuir wave packet in an ion background that either is uniform or has a profile representative of the density wells in which wave packets form during strong plasma turbulence. Collapse thresholds are determined numerically and compared to analytical estimates. A model in which Langmuir damping is significantly stronger than Landau damping is constructed which, when included in the PDE simulations, yields good agreement with the collapse dynamics observed in PIC simulations for wave packets with initial wave energy densities small compared to the thermal level. For more intense initial Langmuir fields, collapse is arrested in PIC simulations at lower field strengths than in PDE simulations. Neither nonlinear saturation of the density perturbation nor fluid electron nonlinearities can account for the difference between simulation methods in this regime. However, at these wave levels inhomogeneous electron heating and coherent jets of transit-time accelerated electrons in phase space are observed, resulting in further enhancement of wave damping and the consequent reduction of fields in the PIC simulations

Pulverized coal burnout in blast furnace simulated by a drop tube furnace

Energy Technology Data Exchange (ETDEWEB)

Du, Shan-Wen [Steel and Aluminum Research and Development Department, China Steel Corporation, Kaohsiung 812 (China); Chen, Wei-Hsin [Department of Greenergy, National University of Tainan, Tainan 700 (China); Lucas, John A. [School of Engineering of the University of Newcastle, Callaghan, NSW 2308 (Australia)

2010-02-15

Reactions of pulverized coal injection (PCI) in a blast furnace were simulated using a drop tube furnace (DTF) to investigate the burnout behavior of a number of coals and coal blends. For the coals with the fuel ratio ranging from 1.36 to 6.22, the experimental results indicated that the burnout increased with decreasing the fuel ratio, except for certain coals departing from the general trend. One of the coals with the fuel ratio of 6.22 has shown its merit in combustion, implying that the blending ratio of the coal in PCI operation can be raised for a higher coke replacement ratio. The experiments also suggested that increasing blast temperature was an efficient countermeasure for promoting the combustibility of the injected coals. Higher fuel burnout could be achieved when the particle size of coal was reduced from 60-100 to 100-200 mesh. However, once the size of the tested coals was in the range of 200 and 325 mesh, the burnout could not be improved further, resulting from the agglomeration of fine particles. Considering coal blend reactions, the blending ratio of coals in PCI may be adjusted by the individual coal burnout rather than by the fuel ratio. (author)

Production of Kaon and Λ in Nucleus-Nucleus Collisions at Ultrarelativistic Energy from a Blast-Wave Model

International Nuclear Information System (INIS)

Chen, J. H.; Zhang, S.; Ma, Y. G.; Zhong, C.

2015-01-01

The particle production of Kaon and Λ is studied in nucleus-nucleus collisions at relativistic energy based on a chemical equilibrium blast-wave model. The transverse momentum spectra of Kaon and Λ at the kinetic freeze-out stage from our model are in good agreement with the experimental results. The kinetic freeze-out parameters of temperature (T kin ) and radial flow parameter ρ 0 are presented for the FOPI, RHIC, and LHC energies. And the resonance decay effect is also discussed. The systematic study for beam energy dependence of the strangeness particle production will help us to better understand the properties of the matter created in heavy-ion collisions at the kinetic freeze-out stage

Radio controlled detonators and sequential real time blast applications

Energy Technology Data Exchange (ETDEWEB)

Bernard, T.; Laboz, J.M. [Delta Caps International, Nice (France)

1995-12-31

Among the numerous technical evolutions in the blasting environment the authors are going to describe below the concept of electronic detonator sequenced by radio waves, and also its numerous applications. Three major technologies are used in the initiation environment: fused-initiated detonators; electric detonators; and non-electric detonators. The last two technologies were made available under multiple variants. Two major innovations are going to substantially change the way traditional detonators operate: pyrotechnic delays are replaced by electronic delays (greater accuracy); and triggering orders, passing through a cable, is now replaced by radio-waves transmission (possibility to do real time delay pattern). Such a new product provided all the features offered by current detonators, but also allows mastering specific cases that were difficult to control with the current technology, such as: vibration control; underground blast; and building demolition.

Wave propagation simulation of radio occultations based on ECMWF refractivity profiles

DEFF Research Database (Denmark)

von Benzon, Hans-Henrik; Høeg, Per

2015-01-01

This paper describes a complete radio occultation simulation environment, including realistic refractivity profiles, wave propagation modeling, instrument modeling, and bending angle retrieval. The wave propagator is used to simulate radio occultation measurements. The radio waves are propagated...... of radio occultations. The output from the wave propagator simulator is used as input to a Full Spectrum Inversion retrieval module which calculates geophysical parameters. These parameters can be compared to the ECMWF atmospheric profiles. The comparison can be used to reveal system errors and get...... a better understanding of the physics. The wave propagation simulations will in this paper also be compared to real measurements. These radio occultations have been exposed to the same atmospheric conditions as the radio occultations simulated by the wave propagator. This comparison reveals that precise...

Blast wave protection of aqueous foams

Energy Technology Data Exchange (ETDEWEB)

Britan, Alexander; Ben-Dor, M. Liverts G. [Shock tube Laboratory of Protective Technologies R and D Center, Department of Mechanical Engineering, Faculty of Engineering Sciences, Ben Gurion University, Beer-Sheva (Israel)

2011-07-01

The primary intention of the present study is to present new contribution of shock tube tests to the problem of particle related stabilization and enhanced mitigation action of the wet particulate foams. The experiments reported were designed to examine (i) the reflection of a shock wave from an air/foam face, (ii) the transmission of the shock wave through the air/foam face and (iii) propagation and dispersion of the transmitted shock wave inside the foam column. Because wet aqueous foam of desired specification is difficult to reproduce, handle and quantitatively characterize the fact that experiments on all the above aspects were conducted in a single facility is a potentially important consideration. Moreover vertical position of shock tube simplified the issues since the gradient of the liquid fraction in draining foam coincides with the shock wave propagation. Under these, much simplified test conditions resulted flows could be treated as one-dimensional and the shock wave mitigation depends on three parameters: the intensity of the incident shock wave, s M , the duration of the foam decay, ∆t and on the particle concentration, n.

CFD Simulations of Floating Point Absorber Wave Energy Converter Arrays Subjected to Regular Waves

Directory of Open Access Journals (Sweden)

Brecht Devolder

2018-03-01

Full Text Available In this paper we use the Computational Fluid Dynamics (CFD toolbox OpenFOAM to perform numerical simulations of multiple floating point absorber wave energy converters (WECs arranged in a geometrical array configuration inside a numerical wave tank (NWT. The two-phase Navier-Stokes fluid solver is coupled with a motion solver to simulate the hydrodynamic flow field around the WECs and the wave-induced rigid body heave motion of each WEC within the array. In this study, the numerical simulations of a single WEC unit are extended to multiple WECs and the complexity of modelling individual floating objects close to each other in an array layout is tackled. The NWT is validated for fluid-structure interaction (FSI simulations by using experimental measurements for an array of two, five and up to nine heaving WECs subjected to regular waves. The validation is achieved by using mathematical models to include frictional forces observed during the experimental tests. For all the simulations presented, a good agreement is found between the numerical and the experimental results for the WECs’ heave motions, the surge forces on the WECs and the perturbed wave field around the WECs. As a result, our coupled CFD–motion solver proves to be a suitable and accurate toolbox for the study of fluid-structure interaction problems of WEC arrays.

Study of the action of blast deck charge in rocky soils

Directory of Open Access Journals (Sweden)

Boiko V.V.

2017-04-01

Full Text Available Blasting (B in the industry, including the mining extraction of minerals, are carried out mostly with the use of blasthole charges that systematically distributed on the block that is undermined, by individual groups. The latter are blasted according to the scheme of short-delay firing (SDF through the intervals that are accepted not less than 20 Ms. Thus, the seismic effect of group charge explosion, consisting of individual blasthole charges and that actually is a group located charge determined by the formula of concentrated charge. Blast deck charges are effectively used in the driving of the trenches in the mining, formation of screens and cracks near the security objects. Only this method of performing blasting allows to define seismic effect in the transition from one diameter of a charge to another, as well as to determine the actual number of detonated charges in one group, which may differ from the calculated in drilling and blasting project. The work analyzes the physical essence of processes happened while blasting of blast deck charges. The effect of the orientation of the seismic action of blasting of blast deck charges towards the allocation line of charges is investigated. The results of generalized dependence of the speed of the displacement of the ground by the blast parameters and epicentral distance are obtained. We demonstrate with specific examples that blast deck charges that blasting simultaneously make a major chain of the career massive explosions at mining. Keywords: seismic fluctuations; the number of charges; the interaction of charges; the distance between the charges; the coefficients of the seismicity and the attenuation of the intensity of the waves; the unit charge; blast deck and blasthole charges; phase shifting; effective charge.

Spectrum of abdominal organ injury in a primary blast type

Directory of Open Access Journals (Sweden)

Amin Abid

2009-12-01

Full Text Available Abstract Introduction Abdominal organ injury in a primary blast type is always challenging for diagnosis. Air containing abdominal viscera is most vulnerable to effects of primary blast injury. In any patient exposed to a primary blast wave who presents with an acute abdomen, an abdominal organ injury is to be kept in a clinical suspicion. Aim Study various abdominal organ injuries occurring in a primary type of blast injury. Material and methods: All those who had exploratory laparotomy for abdominal organ injuries after a primary blast injury for a period of 10 years from January 1998 - January 2008 were included in this retrospective study. Results Total 154 patients had laparotomy for abdominal organ injuries with a primary blast type of injury. Small intestine was damaged in 48 patients (31.1% followed by spleen in 22.7% cases. 54 patients (35.06% had more than one organ injured. Liver laceration was present in 30 patients (19.48%. Multiple small gut perforations were present in 37 patients (77.08%. Negative laparotomy was found in 5 patients (3.24% whereas 3 (1.94% had re-exploration. Mortality was present in 6 patients (3.89%. Conclusions Primary blast injury causes varied abdominal organ injuries. Single or multiple organ damage can be there. Small intestine is commonest viscera injured. Laparotomy gives final diagnosis.

Experimental methods of shock wave research

CERN Document Server

Seiler, Friedrich

2016-01-01

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

Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

Science.gov (United States)

Irshidat, Mohammad

A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

Quarry blasts assessment and their environmental impacts on the nearby oil pipelines, southeast of Helwan City, Egypt

Directory of Open Access Journals (Sweden)

Adel M.E. Mohamed

2013-06-01

Full Text Available Ground vibrations induced by blasting in the cement quarries are one of the fundamental problems in the quarrying industry and may cause severe damage to the nearby utilities and pipelines. Therefore, a vibration control study plays an important role in the minimization of environmental effects of blasting in quarries. The current paper presents the influence of the quarry blasts at the National Cement Company (NCC on the two oil pipelines of SUMED Company southeast of Helwan City, by measuring the ground vibrations in terms of Peak Particle Velocity (PPV. The seismic refraction for compressional waves deduced from the shallow seismic survey and the shear wave velocity obtained from the Multi channel Analysis of Surface Waves (MASW technique are used to evaluate the closest site of the two pipelines to the quarry blasts. The results demonstrate that, the closest site of the two pipelines is of class B, according to the National Earthquake Hazard Reduction Program (NEHRP classification and the safe distance to avoid any environmental effects is 650 m, following the deduced Peak Particle Velocity (PPV and scaled distance (SD relationship (PPV = 700.08 × SD−1.225 in mm/s and the Air over Pressure (air blast formula (air blast = 170.23 × SD−0.071 in dB. In the light of prediction analysis, the maximum allowable charge weight per delay was found to be 591 kg with damage criterion of 12.5 mm/s at the closest site of the SUMED pipelines.

Incorporating information from source simulations into searches for gravitational-wave bursts

International Nuclear Information System (INIS)

Brady, Patrick R; Ray-Majumder, Saikat

2004-01-01

The detection of gravitational waves from astrophysical sources of gravitational waves is a realistic goal for the current generation of interferometric gravitational-wave detectors. Short duration bursts of gravitational waves from core-collapse supernovae or mergers of binary black holes may bring a wealth of astronomical and astrophysical information. The weakness of the waves and the rarity of the events urges the development of optimal methods to detect the waves. The waves from these sources are not generally known well enough to use matched filtering however; this drives the need to develop new ways to exploit source simulation information in both detection and information extraction. We present an algorithmic approach to using catalogues of gravitational-wave signals developed through numerical simulation, or otherwise, to enhance our ability to detect these waves. As more detailed simulations become available, it is straightforward to incorporate the new information into the search method. This approach may also be useful when trying to extract information from a gravitational-wave observation by allowing direct comparison between the observation and simulations

Hot metal temperature prediction and simulation by fuzzy logic in a blast furnace

International Nuclear Information System (INIS)

Romero, M. A.; Jimenez, J.; Mochon, J.; Formoso, A.; Bueno, F.; Menendez, J. L.

2000-01-01

This work describes the development and further validation of a model devoted to blast furnace hot metal temperature forecast, based on Fuzzy logic principles. The model employs as input variables, the control variables of an actual blast furnace: Blast volume, moisture, coal injection, oxygen addition, etc. and it yields as a result the hot metal temperature with a forecast horizon of forty minutes. As far as the variables used to develop the model have been obtained from data supplied by an actual blast furnaces sensors, it is necessary to properly analyse and handle such data. Especial attention was paid to data temporal correlation, fitting by interpolation the different sampling rates. In the training stage of the model the ANFIS (Adaptive Neuro-Fuzzy Inference System) and the Subtractive Clustering algorithms have been used. (Author) 9 refs

Air blast effects on nuclear power plants from vapor cloud explosions

International Nuclear Information System (INIS)

Wiedermann, A.H.; Eichler, T.V.; Kot, C.A.

1981-01-01

To assess the hazards arising from the explosion of a large flammable vapor cloud a method was developed for estimating the air blast field assuming a detonation wave is established. The actual 'pancake' like geometry typical for negatively buoyant vapor clouds is taken into account. The cloud height and other characteristics are generated by a global cloud dynamics model for negatively buoyant clouds. This model provides the cloud height as a function of fuel vapor concentration and other pertinent variables. A two-dimensional Eulerian shock hydrodynamic computer code is utilized to compute the blast environment in the neighborhood of the end of the cloud. The initial field is taken to be a quasi-steady explosion field calculated by the method of characteristics for a thin Prandtl-Meyer expansion wave, and the upward driven air shock representing the combustion and pressure relief processes inherent in the pancake geometry. This initial fields is established in the 2-D hydrocode at a time corresponding to the arrival of the detonation front at the cloud edge. It is to be noted that the local blast environment scales with respect to the cloud height. The computational results indicate that it is essential to include the influence of cloud geometry for the realistic prediction of the air blast hazard arising from the explosion of a negatively buoyant vapor cloud. (orig./HP)

Implementation of a user defined mine blast model in LSDYNA

NARCIS (Netherlands)

Tyler-Street, M.; Leerdam, P.J.C.

2012-01-01

A user defined mine blast model has been developed and implemented into the explicit finite element code LS-DYNA to provide a numerically efficient method for simulating an antivehicular mine blast. The objective is to provide a simple and robust numerical method which is able to represent both the

Analysis of MINIE2013 Explosion Air-Blast Data

Energy Technology Data Exchange (ETDEWEB)

Schnurr, Julie M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Hawaii, Manoa, HI (United States); Rodgers, Arthur J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kim, Keehoon [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ford, Sean R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ramirez, Abelardo L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-14

We report analysis of air-blast overpressure measurements from the MINIE2013 explosive experiments. The MINIE2013 experiment involved a series of nearly 70 near-surface (height-ofburst, HOB, ranging from -1 to +4 m) low-yield (W=2-20 kg TNT equivalent) chemical highexplosives tests that were recorded at local distances (230 m – 28.5 km). Many of the W and HOB combinations were repeated, allowing for quantification of the variability in air-blast features and corresponding yield estimates. We measured canonical signal features (peak overpressure, impulse per unit area, and positive pulse duration) from the air-blast data and compared these to existing air-blast models. Peak overpressure measurements showed good agreement with the models at close ranges but tended to attenuate more rapidly at longer range (~ 1 km), which is likely caused by upward refraction of acoustic waves due to a negative vertical gradient of sound speed. We estimated yields of the MINIE2013 explosions using the Integrated Yield Determination Tool (IYDT). Errors of the estimated yields were on average within 30% of the reported yields, and there were no significant differences in the accuracy of the IYDT predictions grouped by yield. IYDT estimates tend to be lower than ground truth yields, possibly because of reduced overpressure amplitudes by upward refraction. Finally, we report preliminary results on a development of a new parameterized air-blast waveform.

Effects of Simulated Heat Waves on Cardiovascular Functions in Senile Mice

Directory of Open Access Journals (Sweden)

Xiakun Zhang

2014-08-01

Full Text Available The mechanism of the effects of simulated heat waves on cardiovascular disease in senile mice was investigated. Heat waves were simulated in a TEM1880 meteorological environment simulation chamber, according to a heat wave that occurred in July 2001 in Nanjing, China. Eighteen senile mice were divided into control, heat wave, and heat wave BH4 groups, respectively. Mice in the heat wave and heat wave BH4 groups were exposed to simulated heat waves in the simulation chamber. The levels of ET-1, NO, HSP60, SOD, TNF, sICAM-1, and HIF-1α in each group of mice were measured after heat wave simulation. Results show that heat waves decreased SOD activity in the myocardial tissue of senile mice, increased NO, HSP60, TNF, sICAM-1, and HIF-1α levels, and slightly decreased ET-1 levels, BH4 can relieve the effects of heat waves on various biological indicators. After a comprehensive analysis of the experiments above, we draw the followings conclusions regarding the influence of heat waves on senile mice: excess HSP60 activated immune cells, and induced endothelial cells and macrophages to secrete large amounts of ICAM-1, TNF-α, and other inflammatory cytokines, it also activated the inflammation response in the body and damaged the coronary endothelial cell structure, which increased the permeability of blood vessel intima and decreased SOD activity in cardiac tissues. The oxidation of lipoproteins in the blood increased, and large amounts of cholesterol were generated. Cholesterol penetrated the intima and deposited on the blood vessel wall, forming atherosclerosis and leading to the occurrence of cardiovascular disease in senile mice. These results maybe are useful for studying the effects of heat waves on elderly humans, which we discussed in the discussion chapter.

User's Manual for the Simulating Waves Nearshore Model (SWAN)

National Research Council Canada - National Science Library

Allard, Richard

2002-01-01

The Simulating WAves Nearshore (SWAN) model is a numerical wave model used to obtain realistic estimates of wave parameters in coastal areas, lakes, and estuaries from given wind, bottom, and current conditions...

Shock waves & explosions

CERN Document Server

Sachdev, PL

2004-01-01

Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...

Transcriptional Changes in the Mouse Retina after Ocular Blast Injury: A Role for the Immune System.

Science.gov (United States)

Struebing, Felix L; King, Rebecca; Li, Ying; Chrenek, Micah A; Lyuboslavsky, Polina N; Sidhu, Curran S; Iuvone, P Michael; Geisert, Eldon E

2018-01-01

Ocular blast injury is a major medical concern for soldiers and explosion victims due to poor visual outcomes. To define the changes in gene expression following a blast injury to the eye, we examined retinal ribonucleic acid (RNA) expression in 54 mouse strains 5 days after a single 50-psi overpressure air wave blast injury. We observe that almost 40% of genes are differentially expressed with a false discovery rate (FDR) of immune system are activated. Accompanied by lymphocyte invasion into the inner retina, blast injury also results in progressive loss of visual function and retinal ganglion cells (RGCs). Collectively, these data demonstrate how systems genetics can be used to put meaning to the transcriptome changes following ocular blast injury that eventually lead to blindness.

Blasting Damage Predictions by Numerical Modeling in Siahbishe Pumped Storage Powerhouse

Science.gov (United States)

Eslami, Majid; Goshtasbi, Kamran

2018-04-01

One of the popular methods of underground and surface excavations is the use of blasting. Throughout this method of excavation, the loading resulted from blasting can be affected by different geo-mechanical and structural parameters of rock mass. Several factors affect turbulence in underground structures some of which are explosion, vibration, and stress impulses caused by the neighbouring blasting products. In investigating the blasting mechanism one should address the processes which expand with time and cause seismic events. To protect the adjoining structures against any probable deconstruction or damage, it is very important to model the blasting process prior to any actual operation. Efforts have been taken in the present study to demonstrate the potentiality of numerical methods in predicting the specified parameters in order to prevent any probable destruction. For this purpose the blasting process was modeled, according to its natural implementation, in one of the tunnels of Siahbishe dam by the 3DEC and AUTODYN 3D codes. 3DEC was used for modeling the blasting environment as well as the blast holes and AUTODYN 3D for modeling the explosion process in the blast hole. In this process the output of AUTODYN 3D, which is a result of modeling the blast hole and is in the form of stress waves, is entered into 3DEC. For analyzing the amount of destruction made by the blasting operation, the key parameter of Peak Particle Velocity was used. In the end, the numerical modeling results have been compared with the data recorded by the seismographs planted through the tunnel. As the results indicated 3DEC and AUTODYN 3D proved appropriate for analyzing such an issue. Therefore, by means of these two softwares one can analyze explosion processes prior to their implementation and make close estimation of the damage resulting from these processes.

Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers.

Science.gov (United States)

Xu, Kai; Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

2018-04-28

Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural

Brain injuries from blast.

Science.gov (United States)

Bass, Cameron R; Panzer, Matthew B; Rafaels, Karen A; Wood, Garrett; Shridharani, Jay; Capehart, Bruce

2012-01-01

Traumatic brain injury (TBI) from blast produces a number of conundrums. This review focuses on five fundamental questions including: (1) What are the physical correlates for blast TBI in humans? (2) Why is there limited evidence of traditional pulmonary injury from blast in current military field epidemiology? (3) What are the primary blast brain injury mechanisms in humans? (4) If TBI can present with clinical symptoms similar to those of Post-Traumatic Stress Disorder (PTSD), how do we clinically differentiate blast TBI from PTSD and other psychiatric conditions? (5) How do we scale experimental animal models to human response? The preponderance of the evidence from a combination of clinical practice and experimental models suggests that blast TBI from direct blast exposure occurs on the modern battlefield. Progress has been made in establishing injury risk functions in terms of blast overpressure time histories, and there is strong experimental evidence in animal models that mild brain injuries occur at blast intensities that are similar to the pulmonary injury threshold. Enhanced thoracic protection from ballistic protective body armor likely plays a role in the occurrence of blast TBI by preventing lung injuries at blast intensities that could cause TBI. Principal areas of uncertainty include the need for a more comprehensive injury assessment for mild blast injuries in humans, an improved understanding of blast TBI pathophysiology of blast TBI in animal models and humans, the relationship between clinical manifestations of PTSD and mild TBI from blunt or blast trauma including possible synergistic effects, and scaling between animals models and human exposure to blasts in wartime and terrorist attacks. Experimental methodologies, including location of the animal model relative to the shock or blast source, should be carefully designed to provide a realistic blast experiment with conditions comparable to blasts on humans. If traditional blast scaling is

Injection of heavy fuel oil into the blast furnace

Energy Technology Data Exchange (ETDEWEB)

Paloposki, T. [Helsinki Univ. of Technology, Otaniemi (Finland); Hakala, J.; Mannila, P.; Laukkanen, J. [Oulu Univ. (Finland)

1996-12-31

This study deals with the injection and combustion of heavy fuel oil in blast furnaces. The injection of the oil was studied experimentally in a small-scale test rig. The combustion of the oil was analysed with a commercial computer program for flow and combustion simulations. Results from computer simulations show that the combustion of the oil can be improved by decreasing the size of the oil drops and by enhancing the mixing between the oil drops and the hot blast. The devolatilization rate of the oil mainly depends on the size of the oil drops. The combustion rate of the volatiles mainly depends on the effectiveness of turbulent mixing with combustion air. Methods to decrease the size of the oil drops were sought in the experimental part of the study. Experimental results show that the size of the oil drops increases with increasing mass flow rate of the oil and decreases with increasing velocity of the hot blast. Methods to improve the mixing between the oil drops and the hot blast are suggested but have not yet been experimentally tested. (author) (4 refs.)

Injection of heavy fuel oil into the blast furnace

Energy Technology Data Exchange (ETDEWEB)

Paloposki, T [Helsinki Univ. of Technology, Otaniemi (Finland); Hakala, J; Mannila, P; Laukkanen, J [Oulu Univ. (Finland)

1997-12-31

This study deals with the injection and combustion of heavy fuel oil in blast furnaces. The injection of the oil was studied experimentally in a small-scale test rig. The combustion of the oil was analysed with a commercial computer program for flow and combustion simulations. Results from computer simulations show that the combustion of the oil can be improved by decreasing the size of the oil drops and by enhancing the mixing between the oil drops and the hot blast. The devolatilization rate of the oil mainly depends on the size of the oil drops. The combustion rate of the volatiles mainly depends on the effectiveness of turbulent mixing with combustion air. Methods to decrease the size of the oil drops were sought in the experimental part of the study. Experimental results show that the size of the oil drops increases with increasing mass flow rate of the oil and decreases with increasing velocity of the hot blast. Methods to improve the mixing between the oil drops and the hot blast are suggested but have not yet been experimentally tested. (author) (4 refs.)

CrocoBLAST: Running BLAST efficiently in the age of next-generation sequencing.

Science.gov (United States)

Tristão Ramos, Ravi José; de Azevedo Martins, Allan Cézar; da Silva Delgado, Gabrielle; Ionescu, Crina-Maria; Ürményi, Turán Peter; Silva, Rosane; Koca, Jaroslav

2017-11-15

CrocoBLAST is a tool for dramatically speeding up BLAST+ execution on any computer. Alignments that would take days or weeks with NCBI BLAST+ can be run overnight with CrocoBLAST. Additionally, CrocoBLAST provides features critical for NGS data analysis, including: results identical to those of BLAST+; compatibility with any BLAST+ version; real-time information regarding calculation progress and remaining run time; access to partial alignment results; queueing, pausing, and resuming BLAST+ calculations without information loss. CrocoBLAST is freely available online, with ample documentation (webchem.ncbr.muni.cz/Platform/App/CrocoBLAST). No installation or user registration is required. CrocoBLAST is implemented in C, while the graphical user interface is implemented in Java. CrocoBLAST is supported under Linux and Windows, and can be run under Mac OS X in a Linux virtual machine. jkoca@ceitec.cz. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Simulation of Wave-Plus-Current Scour beneath Submarine Pipelines

DEFF Research Database (Denmark)

Eltard-Larsen, Bjarke; Fuhrman, David R.; Sumer, B. Mutlu

2016-01-01

A fully coupled hydrodynamic and morphologic numerical model was utilized for the simulation of wave-plus-current scour beneath submarine pipelines. The model was based on incompressible Reynolds-averaged Navier–Stokes equations, coupled with k-ω turbulence closure, with additional bed and suspen......A fully coupled hydrodynamic and morphologic numerical model was utilized for the simulation of wave-plus-current scour beneath submarine pipelines. The model was based on incompressible Reynolds-averaged Navier–Stokes equations, coupled with k-ω turbulence closure, with additional bed...... and suspended load descriptions forming the basis for seabed morphology. The model was successfully validated against experimental measurements involving scour development and eventual equilibrium in pure-current flows over a range of Shields parameters characteristic of both clear-water and live-bed regimes....... This validation complements previously demonstrated accuracy for the same model in simulating pipeline scour processes in pure-wave environments. The model was subsequently utilized to simulate combined wave-plus-current scour over a wide range of combined Keulegan–Carpenter numbers and relative current strengths...

Biobeam—Multiplexed wave-optical simulations of light-sheet microscopy

Science.gov (United States)

Weigert, Martin; Bundschuh, Sebastian T.

2018-01-01

Sample-induced image-degradation remains an intricate wave-optical problem in light-sheet microscopy. Here we present biobeam, an open-source software package that enables simulation of operational light-sheet microscopes by combining data from 105–106 multiplexed and GPU-accelerated point-spread-function calculations. The wave-optical nature of these simulations leads to the faithful reproduction of spatially varying aberrations, diffraction artifacts, geometric image distortions, adaptive optics, and emergent wave-optical phenomena, and renders image-formation in light-sheet microscopy computationally tractable. PMID:29652879

Full wave simulation of waves in ECRIS plasmas based on the finite element method

Energy Technology Data Exchange (ETDEWEB)

Torrisi, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I (Italy); Mascali, D.; Neri, L.; Castro, G.; Patti, G.; Celona, L.; Gammino, S.; Ciavola, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania (Italy); Di Donato, L. [Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Sorbello, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Isernia, T. [Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I-89100 Reggio Calabria (Italy)

2014-02-12

This paper describes the modeling and the full wave numerical simulation of electromagnetic waves propagation and absorption in an anisotropic magnetized plasma filling the resonant cavity of an electron cyclotron resonance ion source (ECRIS). The model assumes inhomogeneous, dispersive and tensorial constitutive relations. Maxwell's equations are solved by the finite element method (FEM), using the COMSOL Multiphysics{sup ®} suite. All the relevant details have been considered in the model, including the non uniform external magnetostatic field used for plasma confinement, the local electron density profile resulting in the full-3D non uniform magnetized plasma complex dielectric tensor. The more accurate plasma simulations clearly show the importance of cavity effect on wave propagation and the effects of a resonant surface. These studies are the pillars for an improved ECRIS plasma modeling, that is mandatory to optimize the ion source output (beam intensity distribution and charge state, especially). Any new project concerning the advanced ECRIS design will take benefit by an adequate modeling of self-consistent wave absorption simulations.

Prevention of Blast-Related Injuries

Science.gov (United States)

2017-09-01

in a canvas harness. The harness was further supported by a steel frame which was suspended from a metal beam (3.7 m off the ground) mounted on...direction of the wave propagation (Figure 5). After proper alignment of the head with respect to the center of the C4 charge, the steel frame was...further tied to four hooks cemented to the concrete ground with straps to prevent excessive motion during the blast exposure. The intensity of the two

A numerical technique to design blast noise mitigation measures

NARCIS (Netherlands)

Berg, F. van den; Eerden, F.J.M. van der

2007-01-01

Large weapons, such as armor, artillery or demolitions, create a high-energy blast wave. It has a low frequency content, typically between 15 and 125 Hz, and can propagate over large distances. As a result it is a relative important cause for annoyance. Mitigation measures need to be close to the

Computational modeling of blast induced whole-body injury: a review.

Science.gov (United States)

Chanda, Arnab; Callaway, Christian

2018-02-01

Blast injuries affect millions of lives across the globe due to its traumatic after effects on the brain and the whole body. To date, military grade armour materials are designed to mitigate ballistic and shrapnel attacks but are less effective in resisting blast impacts. In order to improve blast absorption characteristics of armours, the first key step is thoroughly understands the effects of blasts on the human body itself. In the last decade, a plethora of experimental and computational work has been carried out to investigate the mechanics and pathophysiology of Traumatic Brain Injury (TBI). However, very few attempts have been made so far to study the effect of blasts on the various other parts of the body such as the sensory organs (eyes and ears), nervous system, thorax, extremities, internal organs (such as the lungs) and the skeletal system. While an experimental evaluation of blast effects on such physiological systems is difficult, developing finite element (FE) models could allow the recreation of realistic blast scenarios on full scale human models and simulate the effects. The current article reviews the state-of-the-art in computational research in blast induced whole-body injury modelling, which would not only help in identifying the areas in which further research is required, but would also be indispensable for understanding body location specific armour design criteria for improved blast injury mitigation.

A new concept of auxiliary fuel injection through tuyeres in blast furnaces developed by numerical simulations

Directory of Open Access Journals (Sweden)

Bruno Orlando de Almeida Santos

2014-04-01

Full Text Available The Injection of powdered materials in blast furnaces is a great option for reducing costs, increasing productivity and satisfy the environmental norms. Thus, this paper presents a study on the use of a flame stabilization system with rotation, designed to promote greater coal injection in the combustion zone, reducing losses and increasing the efficiency of the equipment. A physical model was used to evaluate scattering of pulverized fuel and is compared with numerical results in the same scale. In the second step, a combustion model was added to the numerical simulation, using dimensions of a real blast furnace. Fields like temperature, velocity and behavior of chemical reactions were analyzed. The results showed that double lances promote better particle injection when compared with simple lance for reduced material injection. The new injection system proposed, with swirl numbers of 0.12 and 0.24, promoted a better injection of both reduced material and temperature in the raceway zone. The swirl 0.24 showed superior performance when compared to other injection systems.

Primary blast survival and injury risk assessment for repeated blast exposures.

Science.gov (United States)

Panzer, Matthew B; Bass, Cameron R Dale; Rafaels, Karin A; Shridharani, Jay; Capehart, Bruce P

2012-02-01

The widespread use of explosives by modern insurgents and terrorists has increased the potential frequency of blast exposure in soldiers and civilians. This growing threat highlights the importance of understanding and evaluating blast injury risk and the increase of injury risk from exposure to repeated blast effects. Data from more than 3,250 large animal experiments were collected from studies focusing on the effects of blast exposure. The current study uses 2,349 experiments from the data collection for analysis of the primary blast injury and survival risk for both long- and short-duration blasts, including the effects from repeated exposures. A piecewise linear logistic regression was performed on the data to develop survival and injury risk assessment curves. New injury risk assessment curves uniting long- and short-duration blasts were developed for incident and reflected pressure measures and were used to evaluate the risk of injury based on blast over pressure, positive-phase duration, and the number of repeated exposures. The risk assessments were derived for three levels of injury severity: nonauditory, pulmonary, and fatality. The analysis showed a marked initial decrease in injury tolerance with each subsequent blast exposure. This effect decreases with increasing number of blast exposures. The new injury risk functions showed good agreement with the existing experimental data and provided a simplified model for primary blast injury risk. This model can be used to predict blast injury or fatality risk for single exposure and repeated exposure cases and has application in modern combat scenarios or in setting occupational health limits. .Copyright © 2012 by Lippincott Williams & Wilkins

Performance of Hybrid Steel Fibers Reinforced Concrete Subjected to Air Blast Loading

Directory of Open Access Journals (Sweden)

Mohammed Alias Yusof

2013-01-01

Full Text Available This paper presents the results of the experimental data and simulation on the performance of hybrid steel fiber reinforced concrete (HSFRC and also normal reinforced concrete (NRC subjected to air blast loading. HSFRC concrete mix consists of a combination of 70% long steel hook end fibre and also 30% of short steel hook end fibre with a volume fraction of 1.5% mix. A total of six concrete panels were subjected to air blast using plastic explosive (PE4 weighing 1 kg each at standoff distance of 0.3 meter. The parameters measured are mode of failure under static and blast loading and also peak overpressure that resulted from detonation using high speed data acquisition system. In addition to this simulation work using AUTODYN was carried out and validated using experimental data. The experimental results indicate that hybrid steel fiber reinforced concrete panel (HSFRC possesses excellent resistance to air blast loading as compared to normal reinforced concrete (NRC panel. The simulation results were also found to be close with experimental data. Therefore the results have been validated using experimental data.

Simulation of blast furnace operation during the substitution of coke and pulverized coal with granulated waste plastic

Directory of Open Access Journals (Sweden)

Kovačević Tihomir M.

2014-01-01

Full Text Available The possibility of using the waste plastic as reducing agent in blast furnace for obtaining pig iron is in focus for the past couple year. The simulation of blast furnace process in BFC software has been performed in order to analyze the coke and coals saving, CO2 emission and determining the economic benefits. Three different batches were made for comparative analysis, depending on the batch composition and input of batch components into the blast furnace: case 1 (C1, case 2 (C2 and case 3 (C3. The base case, C1 contains sinter (bulk material which is needed for obtaining 1 tone of pig iron, quartz which provides slag alkalinity and coke as reducing and energy agent. C2 has the same components as C1, but contains pulverized coal instead one part of coke and C3 contains granulated waste plastic instead coke in an approximately the same amount as pulverized coal. The substitution of coke with pulverized coal and waste plastic is 18.6 % and 25.2 %, respectively. The economic, productivity and ecologic aspects have been analyzed. The consumption of each tone of waste plastic in blast furnace saves 360 $, which is 18 times more than its price, bearing in mind that the market price of coke is 380 $/t % and waste plastic 20 $/t. Regarding the specific productivity, it decreases from 2.13 for C1 to 1.87 for C3. From an environmental aspect there are two main benefits: reduction of CO2 emission and impossibility of dioxin formation. The CO2 emission was 20.18, 19.46 and 17.21 for C1, C2 and C3, respectively.

Ultrafast Fabry-Perot fiber-optic pressure sensors for multimedia blast event measurements.

Science.gov (United States)

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2013-02-20

A shock wave (SW) is characterized as a large pressure fluctuation that typically lasts only a few milliseconds. On the battlefield, SWs pose a serious threat to soldiers who are exposed to explosions, which may lead to blast-induced traumatic brain injuries. SWs can also be used beneficially and have been applied to a variety of medical treatments due to their unique interaction with tissues and cells. Consequently, it is important to have sensors that can quantify SW dynamics in order to better understand the physical interaction between body tissue and the incident acoustic wave. In this paper, the ultrafast fiber-optic sensor based on the Fabry-Perot interferometric principle was designed and four such sensors were fabricated to quantify a blast event within different media, simultaneously. The compact design of the fiber-optic sensor allows for a high degree of spatial resolution when capturing the wavefront of the traveling SW. Several blast event experiments were conducted within different media (e.g., air, rubber membrane, and water) to evaluate the sensor's performance. This research revealed valuable knowledge for further study of SW behavior and SW-related applications.

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

Energy Technology Data Exchange (ETDEWEB)

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

2005-01-01

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

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

International Nuclear Information System (INIS)

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

2005-01-01

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

Simulation of dust-acoustic waves

International Nuclear Information System (INIS)

Winske, D.; Murillo, M.S.; Rosenberg, M.

1998-01-01

The authors use molecular dynamics (MD) and particle-in-cell (PIC) simulation methods to investigate the dispersion relation of dust-acoustic waves in a one-dimensional, strongly coupled (Coulomb coupling parameter Λ = ratio of the Coulomb energy to the thermal energy = 120) dusty plasma. They study both cases where the dust is represented by a small number of simulation particles that form into a regular array structure (crystal limit) as well as where the dust is represented by a much larger number of particles (fluid limit)

Characteristics of laser-induced shock wave injury to the inner ear of rats

Science.gov (United States)

Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

2014-12-01

Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

Characteristics of laser-induced shock wave injury to the inner ear of rats.

Science.gov (United States)

Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

2014-12-01

Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

Prevention of Blast-Related Injuries

Science.gov (United States)

2013-07-01

influence of cerebrospinal fluid (CSF) on the shock wave response 3. Development of the geometric model for the head of a 23 55-kg Yucatan pig 4...of Tissue-Tek® optimum cutting compound and 20% sucrose (w/v) and frozen in a stream of liquid nitrogen (Saljo et al, 2008). The frozen blocks will...review of current models of the pig head under air blast loading 2. Development of a 2-D pig head FE model to study the influence of cerebrospinal fluid

Design of wave breaking experiments and A-Posteriori Simulations

NARCIS (Netherlands)

Kurnia, R.; Kurnia, Ruddy; van Groesen, Embrecht W.C.

2014-01-01

This report presents results of 30 wave breaking experiments conducted in the long wave tank of TU Delft, Department of Maritime and Transport Technology (6,7 and 10-12 March 2014), together with simulations performed before the experiment to determine the required wave maker motion and a-posteriori

Design of wave breaking experiments and A-Posteriori Simulations

NARCIS (Netherlands)

Kurnia, Ruddy; van Groesen, Embrecht W.C.

This report presents results of 30 wave breaking experiments conducted in the long wave tank of TU Delft, Department of Maritime and Transport Technology (6,7 and 10-12 March 2014), together with simulations performed before the experiment to determine the required wave maker motion and a-posteriori

Numerical simulation of electrostatic waves in plasmas

International Nuclear Information System (INIS)

Erz, U.

1981-08-01

In this paper the propagation of electrostatic waves in plasmas and the non-linear interactions, which occur in the case of large wave amplitudes, are studied using a new numerical method for plasma simulation. This mathematical description is based on the Vlasov-model. Changes in the distribution-function are taken into account and thus plasma kinetic effects can be treated. (orig./HT) [de

Design of a bounded wave EMP (Electromagnetic Pulse) simulator

Science.gov (United States)

Sevat, P. A. A.

1989-06-01

Electromagnetic Pulse (EMP) simulators are used to simulate the EMP generated by a nuclear weapon and to harden equipment against the effects of EMP. At present, DREO has a 1 m EMP simulator for testing computer terminal size equipment. To develop the R and D capability for testing larger objects, such as a helicopter, a much bigger threat level facility is required. This report concerns the design of a bounded wave EMP simulator suitable for testing large size equipment. Different types of simulators are described and their pros and cons are discussed. A bounded wave parallel plate type simulator is chosen for it's efficiency and the least environmental impact. Detailed designs are given for 6 m and 10 m parallel plate type wire grid simulators. Electromagnetic fields inside and outside the simulators are computed. Preliminary specifications for a pulse generator required for the simulator are also given. Finally, the electromagnetic fields radiated from the simulator are computed and discussed.

Simulations of short-crested harbour waves with variational Boussinesq modelling

NARCIS (Netherlands)

Adytia, D.

2014-01-01

Waves propagating from the deep ocean to the coast show large changes in wave height, wave length and direction. The challenge to simulate the essential wave characteristics is in particular to model the speed and nonlinear interaction correctly. All these physical phenomena are present, but hidden,

Traumatic brain injury produced by exposure to blasts, a critical problem in current wars: biomarkers, clinical studies, and animal models

Science.gov (United States)

Dixon, C. Edward

2011-06-01

Traumatic brain injury (TBI) resulting from exposure to blast energy released by Improvised Explosive Devices (IEDs) has been recognized as the "signature injury" of Operation Iraqi Freedom and Operation Enduring Freedom. Repeated exposure to mild blasts may produce subtle deficits that are difficult to detect and quantify. Several techniques have been used to detect subtle brain dysfunction including neuropsychological assessments, computerized function testing and neuroimaging. Another approach is based on measurement of biologic substances (e.g. proteins) that are released into the body after a TBI. Recent studies measuring biomarkers in CSF and serum from patients with severe TBI have demonstrated the diagnostic, prognostic, and monitoring potential. Advancement of the field will require 1) biochemical mining for new biomarker candidates, 2) clinical validation of utility, 3) technical advances for more sensitive, portable detectors, 4) novel statistical approach to evaluate multiple biomarkers, and 5) commercialization. Animal models have been developed to simulate elements of blast-relevant TBI including gas-driven shock tubes to generate pressure waves similar to those produced by explosives. These models can reproduce hallmark clinical neuropathological responses such as neuronal degeneration and inflammation, as well as behavioral impairments. An important application of these models is to screen novel therapies and conduct proteomic, genomic, and lipodomic studies to mine for new biomarker candidates specific to blast relevant TBI.

Sensitivity of Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations

Science.gov (United States)

2016-06-12

Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations Venkatesh Babu, Kumar Kulkarni, Sanjay...buried in soil viz., (1) coupled discrete element & particle gas methods (DEM-PGM) and (2) Arbitrary Lagrangian-Eulerian (ALE), are investigated. The...DEM_PGM and identify the limitations/strengths compared to the ALE method. Discrete Element Method (DEM) can model individual particle directly, and

quality of computerized blast load simulation for non-linear dynamic

African Journals Online (AJOL)

STRANCOM

1Addis School of Civil and Environmental Engineering, AAiT, Addis Ababa University ... and a special-purpose, blast-specific software product to assess ... engineers in recent years. Important .... the Newmark numerical integration method,.

Testing and modeling the dynamic response of foam materials for blast protection

Science.gov (United States)

Fitek, John H.

The pressure wave released from an explosion can cause injury to the lungs. A personal armor system concept for blast lung injury protection consists of a polymer foam layer behind a rigid armor plate to be worn over the chest. This research develops a method for testing and modeling the dynamic response of foam materials to be used for down-selection of materials for this application. Constitutive equations for foam materials are incorporated into a lumped parameter model of the combined armor plate and foam system. Impact testing and shock tube testing are used to measure the foam model parameters and validate the model response to a pressure wave load. The plate and foam armor model is then coupled to a model of the human thorax. With a blast pressure wave input, the armor model is evaluated based on how it affects the injury-causing mechanism of chest wall motion. Results show that to reduce chest wall motion, the foam must compress at a relatively constant stress level, which requires a sufficient foam thickness.

Computational study of nonlinear plasma waves. I. Simulation model and monochromatic wave propagation

International Nuclear Information System (INIS)

Matsuda, Y.; Crawford, F.W.

1975-01-01

An economical low-noise plasma simulation model originated by Denavit is applied to a series of problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. The model is described and tested, first in the absence of an applied signal, and then with a small amplitude perturbation. These tests serve to establish the low-noise features of the model, and to verify the theoretical linear dispersion relation at wave energy levels as low as 10 -6 of the plasma thermal energy: Better quantitative results are obtained, for comparable computing time, than can be obtained by conventional particle simulation models, or direct solution of the Vlasov equation. The method is then used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories

Gravity wave generation from jets and fronts: idealized and real-case simulations

Science.gov (United States)

Plougonven, Riwal; Arsac, Antonin; Hertzog, Albert; Guez, Lionel; Vial, François

2010-05-01

The generation of gravity waves from jets and fronts remains an outstanding issue in the dynamics of the atmosphere. It is important to explain and quantify this emission because of the several impacts of these waves, in particular the induced momentum fluxes towards the middle atmosphere, and their contribution to turbulence and mixing, e.g. in the region of the tropopause. Yet, the mechanisms at the origin of these waves have been difficult to identify, the fundamental reason for this being the separation between the time scales of balanced motions and gravity waves. Recent simulations of idealized baroclinic life cycles and of dipoles have provided insights into the mechanisms determining the characteristics and the amplitude of gravity waves emitted by jets. It has been shown in particular that the environmental strain and shear play a crucial role in determining the characteristics and location of the emitted waves, emphasizing jet exit regions for the appearance of coherent low-frequency waves. It has also been shown how advection of relatively small-scales allow to overcome the separation of time scales alluded to above. Recent results, remaining open questions and ongoing work on these idealized simulations will be briefly summarized. Nevertheless, unavoidable shortcomings of such idealized simulations include the sensitivity of the emitted waves to model setup (resolution, diffusion, parameterizations) and uncertainty regarding the realism of this aspect of the simulations. Hence, it is necessary to compare simulations with observations in order to assess their relevance. Such comparison has been undertaken using the dataset from the Vorcore campaign (Sept. 2005 - Feb. 2006, Hertzog, J. Atmos. Ocean. Techno. 2007) during which 27 superpressure balloons drifted as quasi-Lagrangian tracers in the lower stratosphere above Antarctica and the Southern Ocean. High-resolution simulations (dx = 20 km) have been carried out using the Weather Research and Forecast

Instability of a planar expansion wave

International Nuclear Information System (INIS)

Velikovich, A.L.; Zalesak, S.T.; Metzler, N.; Wouchuk, J.G.

2005-01-01

An expansion wave is produced when an incident shock wave interacts with a surface separating a fluid from a vacuum. Such an interaction starts the feedout process that transfers perturbations from the rippled inner (rear) to the outer (front) surface of a target in inertial confinement fusion. Being essentially a standing sonic wave superimposed on a centered expansion wave, a rippled expansion wave in an ideal gas, like a rippled shock wave, typically produces decaying oscillations of all fluid variables. Its behavior, however, is different at large and small values of the adiabatic exponent γ. At γ>3, the mass modulation amplitude δm in a rippled expansion wave exhibits a power-law growth with time ∝t β , where β=(γ-3)/(γ-1). This is the only example of a hydrodynamic instability whose law of growth, dependent on the equation of state, is expressed in a closed analytical form. The growth is shown to be driven by a physical mechanism similar to that of a classical Richtmyer-Meshkov instability. In the opposite extreme γ-1 -1/2 , and then starts to decrease. The mechanism driving the growth is the same as that of Vishniac's instability of a blast wave in a gas with low γ. Exact analytical expressions for the growth rates are derived for both cases and favorably compared to hydrodynamic simulation results

Blast Testing Issues and TBI; Experimental Models that Lead to Wrong Conclusions

Directory of Open Access Journals (Sweden)

Charles E. Needham

2015-04-01

Full Text Available Over the past several years we have noticed an increase in the number of blast injury studies published in peer-reviewed biomedical journals that have utilized improperly conceived experiments. Data from these studies will lead to false conclusions and more confusion than advancement in the understanding of blast injury, particularly blast neurotrauma. Computational methods to properly characterize the blast environment have been available for decades. These methods, combined with a basic understanding of blast wave phenomena enable researchers to extract useful information from well documented experiments. This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured. However, it is critical that the research community effectively overcomes the confusion that has been compounded by a misunderstanding of the differences between the loading produced by a free field explosive blast and loading produced by a conventional shock tube. The principles of blast scaling have been well established for decades and when properly applied will do much to repair these problems.This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests. Through application of computational methods, useful data can be extracted from well documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

Simulating Freak Waves in the Ocean with CFD Modeling

Science.gov (United States)

Manolidis, M.; Orzech, M.; Simeonov, J.

2017-12-01

Rogue, or freak, waves constitute an active topic of research within the world scientific community, as various maritime authorities around the globe seek to better understand and more accurately assess the risks that the occurrence of such phenomena entail. Several experimental studies have shed some light on the mechanics of rogue wave formation. In our work we numerically simulate the formation of such waves in oceanic conditions by means of Computational Fluid Dynamics (CFD) software. For this purpose we implement the NHWAVE and OpenFOAM software packages. Both are non-hydrostatic, turbulent flow solvers, but NHWAVE implements a shock-capturing scheme at the free surface-interface, while OpenFOAM utilizes the Volume Of Fluid (VOF) method. NHWAVE has been shown to accurately reproduce highly nonlinear surface wave phenomena, such as soliton propagation and wave shoaling. We conducted a range of tests simulating rogue wave formation and horizontally varying currents to evaluate and compare the capabilities of the two software packages. Then we used each model to investigate the effect of ocean currents and current gradients on the formation of rogue waves. We present preliminary results.

Evaluating the Effectiveness of Various Blast Loading Descriptors as Occupant Injury Predictors for Underbody Blast Events

Science.gov (United States)

2013-08-22

expressed herein do not necessarily state or reflect those of the United States Government or the DoD, and shall not be used for advertising or...Trembelay, J., “Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles,” 7th International LS-DYNA Users Conference

One and two dimensional simulations on beat wave acceleration

International Nuclear Information System (INIS)

Mori, W.; Joshi, C.; Dawson, J.M.; Forslund, D.W.; Kindel, J.M.

1984-01-01

Recently there has been considerable interest in the use of fast-large-amplitude plasma waves as the basis for a high energy particle accelerator. In these schemes, lasers are used to create the plasma wave. To date the few simulation studies on this subject have been limited to one-dimensional, short rise time simulations. Here the authors present results from simulations in which more realistic parameters are used. In addition, they present the first two dimensional simulations on this subject. One dimensional simulations on a 2 1/2-D relativistic electromagnetic particle code, in which only a few cells were used in one direction, on colinear optical mixing are presented. In these simulations the laser rise time, laser intensity, plasma density, plasma temperature and system size were varied. The simulations indicate that the theory of Rosenbluth and Liu is applicable over a wide range of parameters. In addition, simulations with a DC magnetic field are presented in order to study the ''Surfatron'' concept

Cylindrically converging blast waves in air

Science.gov (United States)

Matsuo, H.; Nakamura, Y.

1981-07-01

Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.

Evaluation of the numerical wave model (SWAN) for wave simulation in the Black Sea

Science.gov (United States)

Akpınar, Adem; van Vledder, Gerbrant Ph.; Kömürcü, Murat İhsan; Özger, Mehmet

2012-12-01

This study summaries the implementation of the SWAN model forced by the ECMWF ERA Interim dataset reanalyzed 10 m winds over the Black Sea which will be used to study the wind-wave climate and wave energy potential in the region, and its verification. The SWAN model results were compared with directional buoy measurements at three locations along the north and south coasts of the Black Sea, parametric model results based on the JONSWAP growth relations, and the results of previous studies. The SWAN model has been applied in a third generation and non-stationary mode with spherical coordinates. The linear and exponential growth from wind input, depth-induced wave breaking, bottom friction, whitecapping, four-wave (for deep water) and triad-wave (for shallow water) nonlinear interactions have been activated in the simulations. The results of this study indicate that agreement between simulated and observed wave parameters is satisfactory and it is slightly more accurate than the results of the previous studies. However, it still has lower estimates for the maximum values of both wave parameters. These lower estimates are probably due to too low wind speeds in the applied ECMWF wind fields, which is probably caused by orographic effects, and due to the relatively course resolution in time and space of the ECMWF (ERA-Interim) wind fields for the Black Sea.

Water in blast holes can improve blasting efficiency and cut costs

Energy Technology Data Exchange (ETDEWEB)

O' Regan, G.

1983-08-01

Water in blast holes has been a traditional problem faced by blasting engineers and foremen in surface mining. Presently accepted techniques for blasting in water-filled holes include the use of more expensive water-gel explosives which are denser than water, dewatering of holes by pumping, and blowing out the water with a small charge before loading the main ANFO charge column. These methods involve considerable expense and delay to the normal charge-loading procedure. The author describes a method of using the water in blast holes to improve blasting efficiency and reduce the consumption of explosive.

Blasting activity of the mining industry in the United States

Energy Technology Data Exchange (ETDEWEB)

Richards, P.G. [Lamont-Doherty Earth Observatory, Palisades, NY (United States)

1994-12-31

About 2 megatons of chemcial explosives are used annually in the U.S., principally in mining for coal and metal ores. Most of this explosive is used in surface mines rather than underground mines. On a typical work day there are about 30 explosions greater than 50 tons, including one shot greater than 200 tons. Shots in underground mines are typically much smaller, because of safety considerations. Almost all chemical explosions above 1 ton in the U.S. are ripple-fired and almost all above 10 tons are also shallow. Almost all are intended to break rock or to remove overburden, and are therefore very inefficient, relative to contained single shots, in generating seismic signals at regional ore teleseismic distances. These attributes make explosions used in industry quite different from the Non-Proliferation Experiment. There is very little correlation between the total amount of explosive used in a ripple-fired blast, and the seismic magnitude. Statistics on blasting magnitudes are of interest in the context of monitoring network. There is a blast reported with regional (or duration) magnitude 3.5 or above, in the U.S., a few tens of times a year; but it would appear that the teleseismic magnitude (m{sub b}) of such events are significantly lower than 3.5. Only about 10 to 30 chemical explosions per year in the U.S. are detected teleseismically with m{sub b}>3. Methods of routinely discriminating most chemical explosions from other seismic sources use spectra of regional phases at frequencies up to about 30 Hz, which is significantly higher than frequencies needed for recording teleseismic signals. The best discriminants appear to be the high-frequency spectral ratio of waves with P-wave energy (e.g. Pn or Pg) to waves with S-wave energy (Sn or Lg); and the use of spectrograms, which can be particularly useful in identifying ripple-firing.

Full-wave Simulations of LH Wave Propagation in Toroidal Plasma with non-Maxwellian Electron Distributions

International Nuclear Information System (INIS)

Valeo, E.J.; Phillips, C.K.; Bonoli, P.T.; Wright, J.C.; Brambilla, M.

2007-01-01

The generation of energetic tails in the electron distribution function is intrinsic to lower-hybrid (LH) heating and current drive in weakly collisional magnetically confined plasma. The effects of these deformations on the RF deposition profile have previously been examined within the ray approximation. Recently, the calculation of full-wave propagation of LH waves in a thermal plasma has been accomplished using an adaptation of the TORIC code. Here, initial results are presented from TORIC simulations of LH propagation in a toroidal plasma with non-thermal electrons. The required efficient computation of the hot plasma dielectric tensor is accomplished using a technique previously demonstrated in full-wave simulations of ICRF propagation in plasma with non-thermal ions

Numerical Evaluation on Dynamic Response of Existing Underlying Tunnel Induced by Blasting Excavation of a Subway Tunnel

Directory of Open Access Journals (Sweden)

Jixue Zhou

2017-01-01

Full Text Available In Southwest China, most regions are mountainous, where traditional drill-and-blast method is adopted to excavate relatively harder rocks. However, blasting would cause vibration to adjacent structures and might result in damage or even failure. This paper considers a case where subway tunnel is overlying an existing railway tunnel, while the excavation requires blasting method. Vibration and stress distribution are calculated via Dynamic Finite Element Method (DFEM for both full-face excavation and CD method. Result shows that vibration induced by CD method is only 28% of that caused by full-face blasting with same distance. Peak vibration is located on the lining facing the blasting source, while peak tensile stress is on the other side of the contour due to the reflection of stress wave on strata boundary. And peak value of tensile stress induced by full-face blasting is capable of causing lining failure; thus full-face blasting is not suggested within 40 m beyond the underlying tunnel axis. However, CD method has shown much advantage, since blasting within 25 m is also considered safe to the underlying tunnel. But when the blasting source is as near as 12 m within the underlying tunnel, the CD method is no longer safe.

Numerical Derivation of Iso-Damaged Curve for a Reinforced Concrete Beam Subjected to Blast Loading

Directory of Open Access Journals (Sweden)

Temsah Yehya

2018-01-01

Full Text Available Many engineering facilities are severely damaged by blast loading. Therefore, many manufacturers of sensitive, breakable, and deformed structures (such as facades of glass buildings carry out studies and set standards for these installations to withstand shock waves caused by explosions. Structural engineers also use these standards in their designs for various structural elements by following the ISO Damage Carve, which links pressure and Impulse. As all the points below this curve means that the structure is safe and will not exceed the degree of damage based on the various assumptions made. This research aims to derive the Iso-Damage curve of a reinforced concrete beam exposed to blast wave. An advanced volumetric finite element program (ABAQUS will be used to perform the derivation.

Numerical simulation of wave-induced scour and backfilling processes beneath submarine pipelines

DEFF Research Database (Denmark)

Fuhrman, David R.; Baykal, Cüneyt; Sumer, B. Mutlu

2014-01-01

A fully-coupled hydrodynamic/morphodynamic numerical model is presented and utilized for the simulation of wave-induced scour and backfilling processes beneath submarine pipelines. The model is based on solutions to Reynolds-averaged Navier–Stokes equations, coupled with k−ω turbulence closure......≤30 demonstrate reasonable match with previous experiments, both in terms of the equilibrium scour depth as well as the scour time scale. Wave-induced backfilling processes are additionally studied by subjecting initial conditions taken from scour simulations with larger KC to new wave climates...... characterized by lower KC values. The simulations considered demonstrate the ability of the model to predict backfilling toward expected equilibrium scour depths based on the new wave climate, in line with experimental expectations. The simulated backfilling process is characterized by two stages: (1...

Numerical simulations of convectively excited gravity waves

International Nuclear Information System (INIS)

Glatzmaier, G.A.

1983-01-01

Magneto-convection and gravity waves are numerically simulated with a nonlinear, three-dimensional, time-dependent model of a stratified, rotating, spherical fluid shell heated from below. A Solar-like reference state is specified while global velocity, magnetic field, and thermodynamic perturbations are computed from the anelastic magnetohydrodynamic equations. Convective overshooting from the upper (superadiabatic) part of the shell excites gravity waves in the lower (subadiabatic) part. Due to differential rotation and Coriolis forces, convective cell patterns propagate eastward with a latitudinally dependent phase velocity. The structure of the excited wave motions in the stable region is more time-dependent than that of the convective motions above. The magnetic field tends to be concentrated over giant-cell downdrafts in the convective zone but is affected very little by the wave motion in the stable region

Nonlinear time-dependent simulation of helix traveling wave tubes

International Nuclear Information System (INIS)

Peng Wei-Feng; Yang Zhong-Hai; Hu Yu-Lu; Li Jian-Qing; Lu Qi-Ru; Li Bin

2011-01-01

A one-dimensional nonlinear time-dependent theory for helix traveling wave tubes is studied. A generalized electromagnetic field is applied to the expression of the radio frequency field. To simulate the variations of the high frequency structure, such as the pitch taper and the effect of harmonics, the spatial average over a wavelength is substituted by a time average over a wave period in the equation of the radio frequency field. Under this assumption, the space charge field of the electron beam can be treated by a space charge wave model along with the space charge coefficient. The effects of the radio frequency and the space charge fields on the electrons are presented by the equations of the electron energy and the electron phase. The time-dependent simulation is compared with the frequency-domain simulation for a helix TWT, which validates the availability of this theory. (interdisciplinary physics and related areas of science and technology)

Simulation on breakage of heterogeneous materials caused by detonative loading; Bakugo shogeki ni yoru fukinshitsu zairyo no hakai gensho no simulation

Energy Technology Data Exchange (ETDEWEB)

Sassa, K; Watanabe, T; Ashida, Y [Kyoto University, Kyoto (Japan). Faculty of Engineering

1996-05-01

Investigations were conducted by simulation of breakage of inhomogeneous materials (rock) attributable to detonative loading, which simulation used the Days-2 Code. During the simulation, one-free-face blastings were used for testing a homogeneous structure, horizontal 2-layer structure, and horizontal 3-layer structure. Property values were assigned to the rocks on the assumption that they were sedimentary rocks such as sandstone or mudstone or hard rocks such as granite. As the result, it was found that a detonative loading resulted in shear failure in a sphere near the focus that was followed by radially developed cracks due to tension breakage, that more area is damaged in a soft rock than in a hard rock, that cracks due to breakage are produced by the overlapping of waves directly from the focus and those reflected from the free face in case of one-free-face blastings, that such cracks propagated along the soft rock layer in case there is a soft rock layer in a hard rock, but that breakage does not extend beyond the soft rock layer. 6 refs., 6 figs., 1 tab.

Summary of efficiency testing of standard and high-capacity high-efficiency particulate air filters subjected to simulated tornado depressurization and explosive shock waves

International Nuclear Information System (INIS)

Smith, P.R.; Gregory, W.S.

1985-04-01

Pressure transients in nuclear facility air cleaning systems can originate from natural phenomena such as tornadoes or from accident-induced explosive blast waves. This study was concerned with the effective efficiency of high-efficiency particulate air (HEPA) filters during pressure surges resulting from simulated tornado and explosion transients. The primary objective of the study was to examine filter efficiencies at pressure levels below the point of structural failure. Both standard and high-capacity 0.61-m by 0.61-m HEPA filters were evaluated, as were several 0.2-m by 0.2-m HEPA filters. For a particular manufacturer, the material release when subjected to tornado transients is the same (per unit area) for both the 0.2-m by 0.2-m and the 0.61-m by 0.61-m filters. For tornado transients, the material release was on the order of micrograms per square meter. When subjecting clean HEPA filters to simulated tornado transients with aerosol entrained in the pressure pulse, all filters tested showed a degradation of filter efficiency. For explosive transients, the material release from preloaded high-capacity filters was as much as 340 g. When preloaded high-capacity filters were subjected to shock waves approximately 50% of the structural limit level, 1 to 2 mg of particulate was released

RF wave simulation for cold edge plasmas using the MFEM library

Science.gov (United States)

Shiraiwa, S.; Wright, J. C.; Bonoli, P. T.; Kolev, T.; Stowell, M.

2017-10-01

A newly developed generic electro-magnetic (EM) simulation tool for modeling RF wave propagation in SOL plasmas is presented. The primary motivation of this development is to extend the domain partitioning approach for incorporating arbitrarily shaped SOL plasmas and antenna to the TORIC core ICRF solver, which was previously demonstrated in the 2D geometry [S. Shiraiwa, et. al., "HISTORIC: extending core ICRF wave simulation to include realistic SOL plasmas", Nucl. Fusion in press], to larger and more complicated simulations by including a 3D realistic antenna and integrating RF rectified sheath potential model. Such an extension requires a scalable high fidelity 3D edge plasma wave simulation. We used the MFEM [http://mfem.org], open source scalable C++ finite element method library, and developed a Python wrapper for MFEM (PyMFEM), and then a radio frequency (RF) wave physics module in Python. This approach allows for building a physics layer rapidly, while separating the physics implementation being apart from the numerical FEM implementation. An interactive modeling interface was built on pScope [S Shiraiwa, et. al. Fusion Eng. Des. 112, 835] to work with an RF simulation model in a complicated geometry.

Numerical simulation of electromagnetic wave propagation using time domain meshless method

International Nuclear Information System (INIS)

Ikuno, Soichiro; Fujita, Yoshihisa; Itoh, Taku; Nakata, Susumu; Nakamura, Hiroaki; Kamitani, Atsushi

2012-01-01

The electromagnetic wave propagation in various shaped wave guide is simulated by using meshless time domain method (MTDM). Generally, Finite Differential Time Domain (FDTD) method is applied for electromagnetic wave propagation simulation. However, the numerical domain should be divided into rectangle meshes if FDTD method is applied for the simulation. On the other hand, the node disposition of MTDM can easily describe the structure of arbitrary shaped wave guide. This is the large advantage of the meshless time domain method. The results of computations show that the damping rate is stably calculated in case with R < 0.03, where R denotes a support radius of the weight function for the shape function. And the results indicate that the support radius R of the weight functions should be selected small, and monomials must be used for calculating the shape functions. (author)

Survey of seismic conditions of drilling and blasting operations near overhead electricity power lines

Science.gov (United States)

Korshunov, G. I.; Afanasev, P. I.; Bulbasheva, I. A.

2017-10-01

The monitoring and survey results of drilling and blasting operations are specified during the development of Afanasyevsky deposit of cement raw materials for a 110 kV electricity power lines structure. Seismic explosion waves and air shock waves were registered in the course of monitoring. The dependency of peak particle velocities on the scaled distance and explosive weight by the delay time was obtained.

Simulation of wind wave growth with reference source functions

Science.gov (United States)

Badulin, Sergei I.; Zakharov, Vladimir E.; Pushkarev, Andrei N.

2013-04-01

We present results of extensive simulations of wind wave growth with the so-called reference source function in the right-hand side of the Hasselmann equation written as follows First, we use Webb's algorithm [8] for calculating the exact nonlinear transfer function Snl. Second, we consider a family of wind input functions in accordance with recent consideration [9] ( )s S = ?(k)N , ?(k) = ? ? ?- f (?). in k 0 ?0 in (2) Function fin(?) describes dependence on angle ?. Parameters in (2) are tunable and determine magnitude (parameters ?0, ?0) and wave growth rate s [9]. Exponent s plays a key role in this study being responsible for reference scenarios of wave growth: s = 4-3 gives linear growth of wave momentum, s = 2 - linear growth of wave energy and s = 8-3 - constant rate of wave action growth. Note, the values are close to ones of conventional parameterizations of wave growth rates (e.g. s = 1 for [7] and s = 2 for [5]). Dissipation function Sdiss is chosen as one providing the Phillips spectrum E(?) ~ ?5 at high frequency range [3] (parameter ?diss fixes a dissipation scale of wind waves) Sdiss = Cdissμ4w?N (k)θ(? - ?diss) (3) Here frequency-dependent wave steepness μ2w = E(?,?)?5-g2 makes this function to be heavily nonlinear and provides a remarkable property of stationary solutions at high frequencies: the dissipation coefficient Cdiss should keep certain value to provide the observed power-law tails close to the Phillips spectrum E(?) ~ ?-5. Our recent estimates [3] give Cdiss ? 2.0. The Hasselmann equation (1) with the new functions Sin, Sdiss (2,3) has a family of self-similar solutions of the same form as previously studied models [1,3,9] and proposes a solid basis for further theoretical and numerical study of wave evolution under action of all the physical mechanisms: wind input, wave dissipation and nonlinear transfer. Simulations of duration- and fetch-limited wind wave growth have been carried out within the above model setup to check its

Peri-Elastodynamic Simulations of Guided Ultrasonic Waves in Plate-Like Structure with Surface Mounted PZT

Directory of Open Access Journals (Sweden)

Subir Patra

2018-01-01

Full Text Available Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS and nanodevices for their respective characterization. In this article, the characteristics of the fundamental Lamb wave modes are simulated in a sample plate-like structure. Lamb wave modes are generated using a surface mounted piezoelectric (PZT transducer which is actuated from the top surface. The proposed generalized Peri-elastodynamics method is not only capable of simulating two dimensional (2D in plane wave under plane strain condition formulated previously but also capable of accurately simulating the out of plane Symmetric and Antisymmetric Lamb wave modes in plate like structures in 3D. For structural health monitoring (SHM of plate-like structures and nondestructive evaluation (NDE of MEMS devices, it is necessary to simulate the 3D wave-damage interaction scenarios and visualize the different wave features due to damages. Hence, in addition, to simulating the guided ultrasonic wave modes in pristine material, Lamb waves were also simulated in a damaged plate. The accuracy of the proposed technique is verified by comparing the modes generated in the plate and the mode shapes across the thickness of the plate with theoretical wave analysis.

Peri-Elastodynamic Simulations of Guided Ultrasonic Waves in Plate-Like Structure with Surface Mounted PZT.

Science.gov (United States)

Patra, Subir; Ahmed, Hossain; Banerjee, Sourav

2018-01-18

Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D) Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS) and nanodevices for their respective characterization. In this article, the characteristics of the fundamental Lamb wave modes are simulated in a sample plate-like structure. Lamb wave modes are generated using a surface mounted piezoelectric (PZT) transducer which is actuated from the top surface. The proposed generalized Peri-elastodynamics method is not only capable of simulating two dimensional (2D) in plane wave under plane strain condition formulated previously but also capable of accurately simulating the out of plane Symmetric and Antisymmetric Lamb wave modes in plate like structures in 3D. For structural health monitoring (SHM) of plate-like structures and nondestructive evaluation (NDE) of MEMS devices, it is necessary to simulate the 3D wave-damage interaction scenarios and visualize the different wave features due to damages. Hence, in addition, to simulating the guided ultrasonic wave modes in pristine material, Lamb waves were also simulated in a damaged plate. The accuracy of the proposed technique is verified by comparing the modes generated in the plate and the mode shapes across the thickness of the plate with theoretical wave analysis.

Two-dimensional simulation of broad-band ferrite electromagnetic wave absorbers by using the FDTD method

Energy Technology Data Exchange (ETDEWEB)

Yoon, Hyun Jin; Kim, Dong Il [Korea Maritime University, Busan (Korea, Republic of)

2004-10-15

The purpose of this simulation study is to design and fabricate an electromagnetic (EM) wave absorber in order to develop a wide-band absorber. We have proposed and modeled a bird-eye-type and cutting-cone-type EM wave absorber by using the equivalent material constants method (EMCM), and we simulated them by using a finite-difference time-domain (FDTD) method. A two or a three-dimensional simulation would be desirable to analyze the EM wave absorber characteristics and to develop new structures. The two-dimensional FDTD simulation requires less computer resources than a three-dimensional simulation to consider the structural effects of the EM wave absorbers. The numerical simulation by using the FDTD method shows propagating EM waves in various types of periodic structure EM wave absorbers. Simultaneously, a Fourier analysis is used to characterize the input pulse and the reflected EM waves for ferrite absorbers with various structures. The results have a wide-band reflection-reducing characteristic. The validity of the proposed model was confirmed by comparing the two-dimensional simulation with the experimental results. The simulations were carried out in the frequency band from 30 MHz to 10 GHz.

Two-dimensional simulation of broad-band ferrite electromagnetic wave absorbers by using the FDTD method

International Nuclear Information System (INIS)

Yoon, Hyun Jin; Kim, Dong Il

2004-01-01

The purpose of this simulation study is to design and fabricate an electromagnetic (EM) wave absorber in order to develop a wide-band absorber. We have proposed and modeled a bird-eye-type and cutting-cone-type EM wave absorber by using the equivalent material constants method (EMCM), and we simulated them by using a finite-difference time-domain (FDTD) method. A two or a three-dimensional simulation would be desirable to analyze the EM wave absorber characteristics and to develop new structures. The two-dimensional FDTD simulation requires less computer resources than a three-dimensional simulation to consider the structural effects of the EM wave absorbers. The numerical simulation by using the FDTD method shows propagating EM waves in various types of periodic structure EM wave absorbers. Simultaneously, a Fourier analysis is used to characterize the input pulse and the reflected EM waves for ferrite absorbers with various structures. The results have a wide-band reflection-reducing characteristic. The validity of the proposed model was confirmed by comparing the two-dimensional simulation with the experimental results. The simulations were carried out in the frequency band from 30 MHz to 10 GHz.

Placement of the dam for the no. 2 kambaratinskaya HPP by large-scale blasting: some observations

International Nuclear Information System (INIS)

Shuifer, M. I.; Argal, É. S.

2011-01-01

Results of complex instrument observations of large-scale blasting during construction of the dam for the No. 2 Kambaratinskaya HPP on the Naryn River in the Republic of Kirgizia are analyzed. The purpose of these observations was: to determine the actual parameters of the seismic process, evaluate the effect of air and acoustic shock waves, and investigate the kinematics of the surface formed by the blast in its core region within the mass of fractured rocks.

Prediction of vibration level in tunnel blasting; Tonneru kusshin happa ni yotte reiki sareru shindo no reberu yosoku ho

Energy Technology Data Exchange (ETDEWEB)

Hirata, A. [Kumamoto Industries Univ, Kumamoto (Japan); Yamamoto, M. [Asahi Chemical Industry Co. Ltd., Tokyo (Japan); Inaba, C. [Nishimatsu Construction Co. Ltd., Kanagawa (Japan); Kaneko, K. [Hokkaido Univ (Japan)

1997-08-01

For avoiding the generation of public hazard due to ground vibration causes by blasting in tunneling, it is important to devise a blasting method for ensuring the level of the ground vibration caused thereby under a limit, and an exact predication of ground vibration before blasting is desirable. In this study, the characteristics of the ground vibration caused by tunnel blasting are analyzed, and a summary of amplitude spectra calculating method is described. A theoretical analysis method for predicting the vibration level is proposed based on spectrum-multiplicative method. Vibration caused by multistage blasting in tunneling is most strong and deemed as important. When observing the process of elastic wave motion caused by multistage blasting being measured, the process can be divided into three element processes in frequency area as vibration source spectrum, transmission attenuation spectrum and frequency response function vibrating test, and, with the multiplication of them, the amplitude spectra at an observation portion can be estimated. 12 refs., 12 figs.

Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

Directory of Open Access Journals (Sweden)

Gu Wenbin

2015-01-01

Full Text Available Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater drilling blasting was measured in a field experiment. It shows that the water bottom vibration monitor could collect vibration signals quite effectively in underwater environments. The followed signal analysis shows that the characteristics of water bottom vibration and land ground vibration induced by the same underwater drilling blasting are quite different due to the different geological environments. The amplitude and frequency band of water bottom vibration both exceed those of land ground vibration. Water bottom vibration is mainly in low-frequency band that induced by blasting impact directly acts on rock. Besides the low-frequency component, land vibration contains another higher frequency band component that induced by followed water hammer wave acts on bank slope.

NUMERICAL SIMULATIONS OF CONVERSION TO ALFVÉN WAVES IN SUNSPOTS

International Nuclear Information System (INIS)

Khomenko, E.; Cally, P. S.

2012-01-01

We study the conversion of fast magnetoacoustic waves to Alfvén waves by means of 2.5D numerical simulations in a sunspot-like magnetic configuration. A fast, essentially acoustic, wave of a given frequency and wave number is generated below the surface and propagates upward through the Alfvén/acoustic equipartition layer where it splits into upgoing slow (acoustic) and fast (magnetic) waves. The fast wave quickly reflects off the steep Alfvén speed gradient, but around and above this reflection height it partially converts to Alfvén waves, depending on the local relative inclinations of the background magnetic field and the wavevector. To measure the efficiency of this conversion to Alfvén waves we calculate acoustic and magnetic energy fluxes. The particular amplitude and phase relations between the magnetic field and velocity oscillations help us to demonstrate that the waves produced are indeed Alfvén waves. We find that the conversion to Alfvén waves is particularly important for strongly inclined fields like those existing in sunspot penumbrae. Equally important is the magnetic field orientation with respect to the vertical plane of wave propagation, which we refer to as 'field azimuth'. For a field azimuth less than 90° the generated Alfvén waves continue upward, but above 90° downgoing Alfvén waves are preferentially produced. This yields negative Alfvén energy flux for azimuths between 90° and 180°. Alfvén energy fluxes may be comparable to or exceed acoustic fluxes, depending upon geometry, though computational exigencies limit their magnitude in our simulations.

Compaction wave profiles: Simulations of gas gun experiments

International Nuclear Information System (INIS)

Menikoff, Ralph

2001-01-01

Mesoscale simulations of a compaction wave in a granular bed of HMX have been performed. The grains are fully resolved in order that the compaction, i.e., the porosity behind the wave front, is determined by the elastic-plastic response of the grains rather than by an empirical law for the porosity as a function of pressure. Numerical wave profiles of the pressure and velocity are compared with data from a gas gun experiment. The experiment used an initial porosity of 36%, and the wave had a pressure comparable to the yield strength of the grains. The profiles are measured at the front and back of the granular bed. The transit time for the compaction wave to propagate between the gauges determines the wave speed. The wave speed depends on the porosity behind the wave and is affected by the strength model. The yield strength needed to match the experimental wave speed is discussed. Analysis of the lead wave through the granular bed, based on impedance matches using the Hugoniot loci, indicates that the compaction wave triggers a small amount of burn, less than 1% mass fraction, on the microsecond time scale of the experiment. copyright 2001 American Institute of Physics

Simulation of Asymmetric Lamb Waves for Sensing and Actuation in Plates

Directory of Open Access Journals (Sweden)

A. Ghoshal

2005-01-01

Full Text Available Two approaches used for monitoring the health of thin aerospace structures are active interrogation and passive monitoring. The active interrogation approach generates and receives diagnostic Lamb waves to detect damage, while the passive monitoring technique listens for acoustic waves caused by damage growth. For the application of both methods, it is necessary to understand how Lamb waves propagate through a structure. In this paper, a Physics-Based Model (PBM using classical plate theory is developed to provide a basic understanding of the actual physical process of asymmetric Lamb mode wave generation and propagation in a plate. The closed-form model uses modal superposition to simulate waves generated by piezoceramic patches and by simulated acoustic emissions. The generation, propagation, reflection, interference, and the sensing of the waves are represented in the model, but damage is not explicitly modeled. The developed model is expected to be a useful tool for the Structural Health Monitoring (SHM community, particularly for studying high frequency acoustic wave generation and propagation in lieu of Finite Element models and other numerical models that require significant computational resources. The PBM is capable of simulating many possible scenarios including a variety of test cases, whereas experimental measurements of all of the cases can be costly and time consuming. The model also incorporates the sensor measurement effect, which is an important aspect in damage detection. Continuous and array sensors are modeled, which are efficient for measuring waves because of their distributed nature.

Computational study of nonlinear plasma waves. I. Simulation model and monochromatic wave propagtion

International Nuclear Information System (INIS)

Matda, Y.; Crawford, F.W.

1974-12-01

An economical low noise plasma simulation model is applied to a series of problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. The model is described and tested, first in the absence of an applied signal, and then with a small amplitude perturbation, to establish the low noise features and to verify the theoretical linear dispersion relation at wave energy levels as low as 0.000,001 of the plasma thermal energy. The method is then used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories. The additional phenomena of sideband instability and satellite growth, stimulated by large amplitude wave propagation and the resulting particle trapping, are described. (auth)

Simulation of Guided Wave Interaction with In-Plane Fiber Waviness

Science.gov (United States)

Leckey, Cara A. C.; Juarez, Peter D.

2016-01-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

D-BLAST OFDM with Channel Estimation

Directory of Open Access Journals (Sweden)

Du Jianxuan

2004-01-01

Full Text Available Multiple-input and multiple-output (MIMO systems formed by multiple transmit and receive antennas can improve performance and increase capacity of wireless communication systems. Diagonal Bell Laboratories Layered Space-Time (D-BLAST structure offers a low-complexity solution for realizing the attractive capacity of MIMO systems. However, for broadband wireless communications, channel is frequency-selective and orthogonal frequency division multiplexing (OFDM has to be used with MIMO techniques to reduce system complexity. In this paper, we investigate D-BLAST for MIMO-OFDM systems. We develop a layerwise channel estimation algorithm which is robust to channel variation by exploiting the characteristic of the D-BLAST structure. Further improvement is made by subspace tracking to considerably reduce the error floor. Simulation results show that the layerwise estimators require 1 dB less signal-to-noise ratio (SNR than the traditional blockwise estimator for a word error rate (WER of when Doppler frequency is 40 Hz. Among the layerwise estimators, the subspace-tracking estimator provides a 0.8 dB gain for WER with 200 Hz Doppler frequency compared with the DFT-based estimator.

A new high-performance 3D multiphase flow code to simulate volcanic blasts and pyroclastic density currents: example from the Boxing Day event, Montserrat

Science.gov (United States)

Ongaro, T. E.; Clarke, A.; Neri, A.; Voight, B.; Widiwijayanti, C.

2005-12-01

For the first time the dynamics of directed blasts from explosive lava-dome decompression have been investigated by means of transient, multiphase flow simulations in 2D and 3D. Multiphase flow models developed for the analysis of pyroclastic dispersal from explosive eruptions have been so far limited to 2D axisymmetric or Cartesian formulations which cannot properly account for important 3D features of the volcanic system such as complex morphology and fluid turbulence. Here we use a new parallel multiphase flow code, named PDAC (Pyroclastic Dispersal Analysis Code) (Esposti Ongaro et al., 2005), able to simulate the transient and 3D thermofluid-dynamics of pyroclastic dispersal produced by collapsing columns and volcanic blasts. The code solves the equations of the multiparticle flow model of Neri et al. (2003) on 3D domains extending up to several kilometres in 3D and includes a new description of the boundary conditions over topography which is automatically acquired from a DEM. The initial conditions are represented by a compact volume of gas and pyroclasts, with clasts of different sizes and densities, at high temperature and pressure. Different dome porosities and pressurization models were tested in 2D to assess the sensitivity of the results to the distribution of initial gas pressure, and to the total mass and energy stored in the dome, prior to 3D modeling. The simulations have used topographies appropriate for the 1997 Boxing Day directed blast on Montserrat, which eradicated the village of St. Patricks. Some simulations tested the runout of pyroclastic density currents over the ocean surface, corresponding to observations of over-water surges to several km distances at both locations. The PDAC code was used to perform 3D simulations of the explosive event on the actual volcano topography. The results highlight the strong topographic control on the propagation of the dense pyroclastic flows, the triggering of thermal instabilities, and the elutriation

Interspecies Scaling in Blast Neurotrauma

Science.gov (United States)

2015-08-27

and services to assist recovery . Santa Monica, CA: Rand Corporation. Taylor, PA and Ford, CC. 2009. "Simulation of Blast-Induced Early-Time...reducing this burden, to Washington Headquarters Services , Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite... Warden 2006). As of 2008 it was estimated that approximately 19% or 320,000 OIF/OEF veterans had sustained a TBI (Tanielian et al. 2008). In 2011 a

Observation and simulation of the ionosphere disturbance waves triggered by rocket exhausts

Science.gov (United States)

Lin, Charles C. H.; Chen, Chia-Hung; Matsumura, Mitsuru; Lin, Jia-Ting; Kakinami, Yoshihiro

2017-08-01

Observations and theoretical modeling of the ionospheric disturbance waves generated by rocket launches are investigated. During the rocket passage, time rate change of total electron content (rTEC) enhancement with the V-shape shock wave signature is commonly observed, followed by acoustic wave disturbances and region of negative rTEC centered along the trajectory. Ten to fifteen min after the rocket passage, delayed disturbance waves appeared and propagated along direction normal to the V-shape wavefronts. These observation features appeared most prominently in the 2016 North Korea rocket launch showing a very distinct V-shape rTEC enhancement over enormous areas along the southeast flight trajectory despite that it was also appeared in the 2009 North Korea rocket launch with the eastward flight trajectory. Numerical simulations using the physical-based nonlinear and nonhydrostatic coupled model of neutral atmosphere and ionosphere reproduce promised results in qualitative agreement with the characteristics of ionospheric disturbance waves observed in the 2009 event by considering the released energy of the rocket exhaust as the disturbance source. Simulations reproduce the shock wave signature of electron density enhancement, acoustic wave disturbances, the electron density depletion due to the rocket-induced pressure bulge, and the delayed disturbance waves. The pressure bulge results in outward neutral wind flows carrying neutrals and plasma away from it and leading to electron density depletions. Simulations further show, for the first time, that the delayed disturbance waves are produced by the surface reflection of the earlier arrival acoustic wave disturbances.

Impact of Drill and Blast Excavation on Repository Performance Confirmation

International Nuclear Information System (INIS)

Keller, R.; Francis, N.; Houseworth, J.; Kramer, N.

2000-01-01

There has been considerable work accomplished internationally examining the effects of drill and blast excavation on rock masses surrounding emplacement openings of proposed nuclear waste repositories. However, there has been limited discussion tying the previous work to performance confirmation models such as those proposed for Yucca Mountain, Nevada. This paper addresses a possible approach to joining the available information on drill and blast excavation and performance confirmation. The method for coupling rock damage data from drill and blast models to performance assessment models for fracture flow requires a correlation representing the functional relationship between the peak particle velocity (PPV) vibration levels and the potential properties that govern water flow rates in the host rock. Fracture aperture and frequency are the rock properties which may be most influenced by drill and blast induced vibration. If it can be shown (using an appropriate blasting model simulation) that the effect of blasting is far removed from the waste package in an emplacement drift, then disturbance to the host rock induced in the process of drill and blast excavation may be reasonably ignored in performance assessment calculations. This paper proposes that the CANMET (Canada Center for Mineral and Energy Technology) Criterion, based on properties that determine rock strength, may be used to define a minimum PPV. This PPV can be used to delineate the extent of blast induced damage. Initial applications have demonstrated that blasting models can successfully be coupled with this criterion to predict blast damage surrounding underground openings. The Exploratory Studies Facility at Yucca Mountain has used a blasting model to generate meaningful estimates of near-field vibration levels and damage envelopes correlating to data collected from pre-existing studies conducted. Further work is underway to expand this application over a statistical distribution of geologic

Gas explosion characterization, wave propagation (small-scale experiments)

International Nuclear Information System (INIS)

Larsen, G.C.

1985-01-01

A number of experiments have been performed with blast waves arising from the ignition of homogeneous and well defined mixtures of methane, oxygen and nitrogen, contained within spherical balloons with controlled initial dimensions. In the initial small scale experiments pressure characteristics, ground reflection phenomena and pressure distribution on box like obstacles were studied. Both configurations with one box and two closely spaced boxes have been considered, and a wave-wave interaction phenomenom was observed in the case of closely spaced obstacles. Main emphasis has been placed on the half scale field experiments. In these, the maximum flame speed has been of the order of 100 m/s, resulting in positive peak pressures of 50-100.10 2 Pa in 5 - 10 m distance from the source. The explosion process was found to be reasonable symmetric. The attenuation of the blast wave due to vegetation and the influence of obstacles as banks, walls and houses on the pressure field have been investigated. The presence of the bank and the house was felt in a zone with a length corresponding to a typical dimension of the obstacles, whereas the overall pressure field is shown to be unaffected by the type of obstacles and vegetation investigated. For the wall and house, reflection factors have been established, and some variation over the surface has been measured. The scatter of the pressure measurements is estimated for stable, neutral and unstable atmospheric conditions, and an attempt to determine the ground reflection factor has been performed. Finally the accelerations of a house exposed to the blast wave have been examined

Simulation of flooding waves in vertical churn flow

Energy Technology Data Exchange (ETDEWEB)

Tekavčič, Matej, E-mail: matej.tekavcic@ijs.si; Končar, Boštjan; Kljenak, Ivo

2016-04-01

Highlights: • Flooding waves in air–water churn flow in a vertical pipe were studied. • Simulations using two-fluid model with interface sharpening were performed. • Calculated wave amplitudes agree with existing experimental data. • Contributions of force terms in the liquid momentum balance equation are presented. - Abstract: A transient simulation of flooding waves in the churn flow of air and water in a vertical pipe is performed by the means of two-fluid modelling approach with interface sharpening. The gas and liquid phases are considered immiscible and incompressible with no mass transfer between them. Inter-phase coupling of momentum is realized via interface drag force which is based on the interface area density and the relative velocity between the phases. Surface tension effects are modelled with the Continuum Surface Model. The flow is assumed isothermal. Turbulence is modelled for each phase separately using the two-equation eddy viscosity approach. Results are compared with the reported experimental data for churn flow regime in a vertical pipe (Wang et al., 2011a). Reynolds numbers of the gas flow are in the range from 6000 to 10,000, while the liquid mass flow rate upwards ranges from 25 to 32 g/s. Prediction of critical and maximum amplitudes of the flooding waves show good agreement with experimental values. Results for wave frequencies indicate significant deviations, which can be attributed to the choice of the liquid inlet model.

Simulation of flooding waves in vertical churn flow

International Nuclear Information System (INIS)

Tekavčič, Matej; Končar, Boštjan; Kljenak, Ivo

2016-01-01

Highlights: • Flooding waves in air–water churn flow in a vertical pipe were studied. • Simulations using two-fluid model with interface sharpening were performed. • Calculated wave amplitudes agree with existing experimental data. • Contributions of force terms in the liquid momentum balance equation are presented. - Abstract: A transient simulation of flooding waves in the churn flow of air and water in a vertical pipe is performed by the means of two-fluid modelling approach with interface sharpening. The gas and liquid phases are considered immiscible and incompressible with no mass transfer between them. Inter-phase coupling of momentum is realized via interface drag force which is based on the interface area density and the relative velocity between the phases. Surface tension effects are modelled with the Continuum Surface Model. The flow is assumed isothermal. Turbulence is modelled for each phase separately using the two-equation eddy viscosity approach. Results are compared with the reported experimental data for churn flow regime in a vertical pipe (Wang et al., 2011a). Reynolds numbers of the gas flow are in the range from 6000 to 10,000, while the liquid mass flow rate upwards ranges from 25 to 32 g/s. Prediction of critical and maximum amplitudes of the flooding waves show good agreement with experimental values. Results for wave frequencies indicate significant deviations, which can be attributed to the choice of the liquid inlet model.

ICRF Mode Conversion Studies with Phase Contrast Imaging and Comparisons with Full-Wave Simulations

International Nuclear Information System (INIS)

Tsujii, N.; Bonoli, P. T.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Porkolab, M.; Jaeger, E. F.; Harvey, R. W.

2011-01-01

Waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat toka-mak plasmas. In a multi-ion-species plasma, the FW converts to ion cyclotron waves (ICW) and ion Bernstein waves (IBW) around the ion-ion hybrid resonance (mode conversion). The mode converted wave is of interest as an actuator to optimise plasma performance through flow drive and current drive. Numerical simulations are essential to describe these processes accurately, and it is important that these simulation codes be validated. On Alcator C-Mod, direct measurements of the mode converted waves have been performed using Phase Contrast Imaging (PCI), which measures the line-integrated electron density fluctuations. The results were compared to full-wave simulations AORSA and TORIC. AORSA is coupled to a Fokker-Planck code CQL3D for self-consistent simulation of the wave electric field and the minority distribution function. The simulation results are compared to PCI measurements using synthetic diagnostic. The experiments were performed in D-H and D- 3 He plasmas over a wide range of ion species concentrations. The simulations agreed well with the measurements in the strong absorption regime. However, the measured fluctuation intensity was smaller by 1-2 orders of magnitudes in the weakly abosorbing regime, and a realistic description of the plasma edge including dissipation and antenna geometry may be required in these cases.

Membranes replace irradiated blast cells as growth requirement for leukemic blast progenitors in suspension culture

International Nuclear Information System (INIS)

Nara, N.; McCulloch, E.A.

1985-01-01

The blast cells of acute myeloblastic leukemia (AML) may be considered as a renewal population, maintained by blast stem cells capable of both self-renewal and the generation of progeny with reduced or absent proliferative potential. This growth requires that two conditions be met: first, the cultures must contain growth factors in media conditioned either by phytohemagglutinin (PHA)-stimulated mononuclear leukocytes (PHA-LCM), or by cells of the continuous bladder carcinoma line HTB9 (HTB9-CM). Second, the cell density must be maintained at 10(6) blasts/ml; this may be achieved by adding irradiated cells to smaller numbers of intact blasts. The authors are concerned with the mechanism of the feeding function. They present evidence that (a) cell-cell contact is required. (b) Blasts are heterogeneous in respect to their capacity to support growth. (c) Fractions containing membranes from blast cells will substitute for intact cells in promoting the generation of new blast progenitors in culture. (d) This membrane function may be specific for AML blasts, since membranes from blasts of lymphoblastic leukemia or normal marrow cells were inactive

Full wave simulations of lower hybrid wave propagation in tokamaks

International Nuclear Information System (INIS)

Wright, J. C.; Bonoli, P. T.; Phillips, C. K.; Valeo, E.; Harvey, R. W.

2009-01-01

Lower hybrid (LH) waves have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons at (2.5-3)xv te , where v te ≡ (2T e /m e ) 1/2 is the electron thermal speed. Consequently these waves are well-suited to driving current in the plasma periphery where the electron temperature is lower, making LH current drive (LHCD) a promising technique for off-axis (r/a≥0.60) current profile control in reactor grade plasmas. Established techniques for computing wave propagation and absorption use WKB expansions with non-Maxwellian self-consistent distributions.In typical plasma conditions with electron densities of several 10 19 m -3 and toroidal magnetic fields strengths of 4 Telsa, the perpendicular wavelength is of the order of 1 mm and the parallel wavelength is of the order of 1 cm. Even in a relatively small device such as Alcator C-Mod with a minor radius of 22 cm, the number of wavelengths that must be resolved requires large amounts of computational resources for the full wave treatment. These requirements are met with a massively parallel version of the TORIC full wave code that has been adapted specifically for the simulation of LH waves [J. C. Wright, et al., Commun. Comput. Phys., 4, 545 (2008), J. C. Wright, et al., Phys. Plasmas 16 July (2009)]. This model accurately represents the effects of focusing and diffraction that occur in LH propagation. It is also coupled with a Fokker-Planck solver, CQL3D, to provide self-consistent distribution functions for the plasma dielectric as well as a synthetic hard X-ray (HXR) diagnostic for direct comparisons with experimental measurements of LH waves.The wave solutions from the TORIC-LH zero FLR model will be compared to the results from ray tracing from the GENRAY/CQL3D code via the synthetic HXR diagnostic and power deposition.

Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

Directory of Open Access Journals (Sweden)

XinPing Li

2017-01-01

Full Text Available Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

Two-material optimization of plate armour for blast mitigation using hybrid cellular automata

Science.gov (United States)

Goetz, J.; Tan, H.; Renaud, J.; Tovar, A.

2012-08-01

With the increased use of improvised explosive devices in regions at war, the threat to military and civilian life has risen. Cabin penetration and gross acceleration are the primary threats in an explosive event. Cabin penetration crushes occupants, damaging the lower body. Acceleration causes death at high magnitudes. This investigation develops a process of designing armour that simultaneously mitigates cabin penetration and acceleration. The hybrid cellular automaton (HCA) method of topology optimization has proven efficient and robust in problems involving large, plastic deformations such as crash impact. Here HCA is extended to the design of armour under blast loading. The ability to distribute two metallic phases, as opposed to one material and void, is also added. The blast wave energy transforms on impact into internal energy (IE) inside the solid medium. Maximum attenuation occurs with maximized IE. The resulting structures show HCA's potential for designing blast mitigating armour structures.

Numerical Simulations of Upstream Propagating Solitary Waves and Wave Breaking In A Stratified Fjord

Science.gov (United States)

Stastna, M.; Peltier, W. R.

In this talk we will discuss ongoing numerical modeling of the flow of a stratified fluid over large scale topography motivated by observations in Knight Inlet, a fjord in British Columbia, Canada. After briefly surveying the work done on the topic in the past we will discuss our latest set of simulations in which we have observed the gener- ation and breaking of three different types of nonlinear internal waves in the lee of the sill topography. The first type of wave observed is a large lee wave in the weakly strat- ified main portion of the water column, The second is an upward propagating internal wave forced by topography that breaks in the strong, near-surface pycnocline. The third is a train of upstream propagating solitary waves that, in certain circumstances, form as breaking waves consisting of a nearly solitary wave envelope and a highly unsteady core near the surface. Time premitting, we will comment on the implications of these results for our long term goal of quantifying tidally driven mixing in Knight Inlet.

Internally driven inertial waves in geodynamo simulations

Science.gov (United States)

Ranjan, A.; Davidson, P. A.; Christensen, U. R.; Wicht, J.

2018-05-01

Inertial waves are oscillations in a rotating fluid, such as the Earth's outer core, which result from the restoring action of the Coriolis force. In an earlier work, it was argued by Davidson that inertial waves launched near the equatorial regions could be important for the α2 dynamo mechanism, as they can maintain a helicity distribution which is negative (positive) in the north (south). Here, we identify such internally driven inertial waves, triggered by buoyant anomalies in the equatorial regions in a strongly forced geodynamo simulation. Using the time derivative of vertical velocity, ∂uz/∂t, as a diagnostic for traveling wave fronts, we find that the horizontal movement in the buoyancy field near the equator is well correlated with a corresponding movement of the fluid far from the equator. Moreover, the azimuthally averaged spectrum of ∂uz/∂t lies in the inertial wave frequency range. We also test the dispersion properties of the waves by computing the spectral energy as a function of frequency, ϖ, and the dispersion angle, θ. Our results suggest that the columnar flow in the rotation-dominated core, which is an important ingredient for the maintenance of a dipolar magnetic field, is maintained despite the chaotic evolution of the buoyancy field on a fast timescale by internally driven inertial waves.

Graphene oxide as sensitive layer in Love-wave surface acoustic wave sensors for the detection of chemical warfare agent simulants.

Science.gov (United States)

Sayago, Isabel; Matatagui, Daniel; Fernández, María Jesús; Fontecha, José Luis; Jurewicz, Izabela; Garriga, Rosa; Muñoz, Edgar

2016-02-01

A Love-wave device with graphene oxide (GO) as sensitive layer has been developed for the detection of chemical warfare agent (CWA) simulants. Sensitive films were fabricated by airbrushing GO dispersions onto Love-wave devices. The resulting Love-wave sensors detected very low CWA simulant concentrations in synthetic air at room temperature (as low as 0.2 ppm for dimethyl-methylphosphonate, DMMP, a simulant of sarin nerve gas, and 0.75 ppm for dipropylene glycol monomethyl ether, DPGME, a simulant of nitrogen mustard). High responses to DMMP and DPGME were obtained with sensitivities of 3087 and 760 Hz/ppm respectively. Very low limit of detection (LOD) values (9 and 40 ppb for DMMP and DPGME, respectively) were calculated from the achieved experimental data. The sensor exhibited outstanding sensitivity, good linearity and repeatability to all simulants tested. The detection mechanism is here explained in terms of hydrogen bonding formation between the tested CWA simulants and GO. Copyright © 2015 Elsevier B.V. All rights reserved.

Design of full scale wave simulator for testing Power Take Off systems for wave energy converters

DEFF Research Database (Denmark)

Pedersen, H. C.; Hansen, R. H.; Hansen, Anders Hedegaard

2016-01-01

is therefore on the design and commissioning of a full scale wave simulator for testing PTO-systems for point absorbers. The challenge is to be able to design a system, which mimics the behavior of a wave when interacting with a given PTO-system – especially when considering discrete type PTO...

Simulation of non-hydrostatic gravity wave propagation in the upper atmosphere

Directory of Open Access Journals (Sweden)

Y. Deng

2014-04-01

Full Text Available The high-frequency and small horizontal scale gravity waves may be reflected and ducted in non-hydrostatic simulations, but usually propagate vertically in hydrostatic models. To examine gravity wave propagation, a preliminary study has been conducted with a global ionosphere–thermosphere model (GITM, which is a non-hydrostatic general circulation model for the upper atmosphere. GITM has been run regionally with a horizontal resolution of 0.2° long × 0.2° lat to resolve the gravity wave with wavelength of 250 km. A cosine wave oscillation with amplitude of 30 m s−1 has been applied to the zonal wind at the low boundary, and both high-frequency and low-frequency waves have been tested. In the high-frequency case, the gravity wave stays below 200 km, which indicates that the wave is reflected or ducted in propagation. The results are consistent with the theoretical analysis from the dispersion relationship when the wavelength is larger than the cutoff wavelength for the non-hydrostatic situation. However, the low-frequency wave propagates to the high altitudes during the whole simulation period, and the amplitude increases with height. This study shows that the non-hydrostatic model successfully reproduces the high-frequency gravity wave dissipation.

Simulating Seismic Wave Propagation in Viscoelastic Media with an Irregular Free Surface

Science.gov (United States)

Liu, Xiaobo; Chen, Jingyi; Zhao, Zhencong; Lan, Haiqiang; Liu, Fuping

2018-05-01

In seismic numerical simulations of wave propagation, it is very important for us to consider surface topography and attenuation, which both have large effects (e.g., wave diffractions, conversion, amplitude/phase change) on seismic imaging and inversion. An irregular free surface provides significant information for interpreting the characteristics of seismic wave propagation in areas with rugged or rapidly varying topography, and viscoelastic media are a better representation of the earth's properties than acoustic/elastic media. In this study, we develop an approach for seismic wavefield simulation in 2D viscoelastic isotropic media with an irregular free surface. Based on the boundary-conforming grid method, the 2D time-domain second-order viscoelastic isotropic equations and irregular free surface boundary conditions are transferred from a Cartesian coordinate system to a curvilinear coordinate system. Finite difference operators with second-order accuracy are applied to discretize the viscoelastic wave equations and the irregular free surface in the curvilinear coordinate system. In addition, we select the convolutional perfectly matched layer boundary condition in order to effectively suppress artificial reflections from the edges of the model. The snapshot and seismogram results from numerical tests show that our algorithm successfully simulates seismic wavefields (e.g., P-wave, Rayleigh wave and converted waves) in viscoelastic isotropic media with an irregular free surface.

Blast-Induced Tinnitus and Elevated Central Auditory and Limbic Activity in Rats: A Manganese-Enhanced MRI and Behavioral Study.

Science.gov (United States)

Ouyang, Jessica; Pace, Edward; Lepczyk, Laura; Kaufman, Michael; Zhang, Jessica; Perrine, Shane A; Zhang, Jinsheng

2017-07-07

Blast-induced tinitus is the number one service-connected disability that currently affects military personnel and veterans. To elucidate its underlying mechanisms, we subjected 13 Sprague Dawley adult rats to unilateral 14 psi blast exposure to induce tinnitus and measured auditory and limbic brain activity using manganese-enhanced MRI (MEMRI). Tinnitus was evaluated with a gap detection acoustic startle reflex paradigm, while hearing status was assessed with prepulse inhibition (PPI) and auditory brainstem responses (ABRs). Both anxiety and cognitive functioning were assessed using elevated plus maze and Morris water maze, respectively. Five weeks after blast exposure, 8 of the 13 blasted rats exhibited chronic tinnitus. While acoustic PPI remained intact and ABR thresholds recovered, the ABR wave P1-N1 amplitude reduction persisted in all blast-exposed rats. No differences in spatial cognition were observed, but blasted rats as a whole exhibited increased anxiety. MEMRI data revealed a bilateral increase in activity along the auditory pathway and in certain limbic regions of rats with tinnitus compared to age-matched controls. Taken together, our data suggest that while blast-induced tinnitus may play a role in auditory and limbic hyperactivity, the non-auditory effects of blast and potential traumatic brain injury may also exert an effect.

Computer simulations of collisionless shock waves

International Nuclear Information System (INIS)

Leroy, M.M.

1984-01-01

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

Investigations of Tissue-Level Mechanisms of Primary Blast Injury Through Modeling, Simulation, Neuroimaging and Neuropathological Studies

Science.gov (United States)

2012-07-10

2007;25(1):97-98. [19] Stewart C. Blast Injuries. Colorado Springs: USAF Academy Hospital; 2006. 88 p. [20] Cernak I, Wang Z, Jiang J, Bian X, Savic J...Wang Z, Jiang J, Bian X, Savic J. Ultrastructural and Functional Characteristics of Blast Injury- Induced Neurotrauma. Journal of Trauma: Injury

Simulation analysis of rectangular dielectric-loaded traveling wave amplifiers for THz sources

Directory of Open Access Journals (Sweden)

Changbiao Wang

2007-12-01

Full Text Available Nonlinear simulation results for a 220-GHz rectangular dielectric-loaded traveling-wave amplifier are presented. Simulations are used to check a linear theory that is developed by phenomenological introduction of an effective dielectric parameter for electron beam channel, and it is found that the rf power gains from Pierce three-wave theory and particle simulations are in reasonable agreement. It is shown that the rf power gain during initial beam-wave interaction is positive; the falling on the initial rf power profile, which has been thought to be the rf power transferred to the beam for bunching buildup (negative gain effect, is probably resulting from numerical errors. Beam-wave interaction mechanism is analyzed by examining the evolution of beam bunching centers. Influences of various parameters on amplifier performance are examined, and transverse space-charge effect is analyzed. A symmetric excitation scheme for rf couplers is proposed, and rf field jumps on the common intersection line of vacuum, dielectric, and metal wall, which were found in rf simulations, are explained theoretically.

NOBLAST and JAMBLAST: New Options for BLAST and a Java Application Manager for BLAST results.

Science.gov (United States)

Lagnel, Jacques; Tsigenopoulos, Costas S; Iliopoulos, Ioannis

2009-03-15

NOBLAST (New Options for BLAST) is an open source program that provides a new user-friendly tabular output format for various NCBI BLAST programs (Blastn, Blastp, Blastx, Tblastn, Tblastx, Mega BLAST and Psi BLAST) without any use of a parser and provides E-value correction in case of use of segmented BLAST database. JAMBLAST using the NOBLAST output allows the user to manage, view and filter the BLAST hits using a number of selection criteria. A distribution package of NOBLAST and JAMBLAST including detailed installation procedure is freely available from http://sourceforge.net/projects/JAMBLAST/ and http://sourceforge.net/projects/NOBLAST. Supplementary data are available at Bioinformatics online.

Coupling atmospheric and ocean wave models for storm simulation

DEFF Research Database (Denmark)

Du, Jianting

the atmosphere must, by conservation, result in the generation of the surface waves and currents. The physics-based methods are sensitive to the choice of wind-input source function (Sin), parameterization of high-frequency wave spectra tail, and numerical cut-off frequencies. Unfortunately, literature survey......This thesis studies the wind-wave interactions through the coupling between the atmospheric model and ocean surface wave models. Special attention is put on storm simulations in the North Sea for wind energy applications in the coastal zones. The two aspects, namely storm conditions and coastal...... shows that in most wind-wave coupling systems, either the Sin in the wave model is different from the one used for the momentum flux estimation in the atmospheric model, or the methods are too sensitive to the parameterization of high-frequency spectra tail and numerical cut-off frequencies. To confront...

Stress Wave Propagation in Larch Plantation Trees-Numerical Simulation

Science.gov (United States)

Fenglu Liu; Fang Jiang; Xiping Wang; Houjiang Zhang; Wenhua Yu

2015-01-01

In this paper, we attempted to simulate stress wave propagation in virtual tree trunks and construct two dimensional (2D) wave-front maps in the longitudinal-radial section of the trunk. A tree trunk was modeled as an orthotropic cylinder in which wood properties along the fiber and in each of the two perpendicular directions were different. We used the COMSOL...

Blast from pressurized carbon dioxide released into a vented atmospheric chamber

Science.gov (United States)

Hansen, P. M.; Gaathaug, A. V.; Bjerketvedt, D.; Vaagsaether, K.

2018-03-01

This study describes the blast from pressurized carbon dioxide (CO2) released from a high-pressure reservoir into an openly vented atmospheric chamber. Small-scale experiments with pure vapor and liquid/vapor mixtures were conducted and compared with simulations. A motivation was to investigate the effects of vent size and liquid content on the peak overpressure and impulse response in the atmospheric chamber. The comparison of vapor-phase CO2 test results with simulations showed good agreement. This numerical code described single-phase gas dynamics inside a closed chamber, but did not model any phase transitions. Hence, the simulations described a vapor-only test into an unvented chamber. Nevertheless, the simulations reproduced the incident shock wave, the shock reflections, and the jet release inside the atmospheric chamber. The rapid phase transition did not contribute to the initial shock strength in the current test geometry. The evaporation rate was too low to contribute to the measured peak overpressure that was in the range of 15-20 kPa. The simulation results produced a calculated peak overpressure of 12 kPa. The liquid tests showed a significantly higher impulse compared to tests with pure vapor. Reducing the vent opening from 0.1 to 0.01 m2 resulted in a slightly higher impulse calculated at 100 ms. The influence of the vent area on the calculated impulse was significant in the vapor-phase tests, but not so clear in the liquid/vapor mixture tests.

Wave tank to simulate the movement of oil under breaking waves

International Nuclear Information System (INIS)

Botrus, D.; Wickley-Olsen, E.; Boufadel, M.C.; Weaver, J.W.; Weggle, R.; Lee, K.; Venosa, A.D.

2008-01-01

Methods to mitigate offshore oil spills before they reach the shoreline have been investigated in order to reduce environmental impacts. Artificial dispersants are commonly used on offshore oil spills to decrease the interfacial tension between the oil and water. The wave action helps break the slick into droplets that penetrate into the sea. This paper presented the results of wave tank tests in which the effectiveness of dispersants was evaluated. The focus was on the transport of oil during the breakup of a wave. In this study, the energy dissipation rate per unit mass was evaluated at various depths in the tank for regular and breaking waves. It was shown that breaking waves play an important role in the dispersion of oil at sea. Contrary to previous studies which suggested that the plume moves forward following the breaker, the results of this study showed that the plume splits into two parts, with one part going upstream. Understanding how the plume travels will provide insight as to where to add the dispersant with respect to the location of the breaker. The addition of the dispersant should take place before the location of the breaker. It was concluded that future work should include computational fluid dynamics simulation, as well as the use of a higher resolution camera. 9 refs., 17 figs

Fluid dynamics of the 1997 Boxing Day volcanic blast on Montserrat, West Indies

Science.gov (United States)

Esposti Ongaro, T.; Clarke, A. B.; Neri, A.; Voight, B.; Widiwijayanti, C.

2008-03-01

Directed volcanic blasts are powerful explosions with a significant laterally directed component, which can generate devastating, high-energy pyroclastic density currents (PDCs). Such blasts are an important class of eruptive phenomena, but quantified understanding of their dynamics and effects is still incomplete. Here we use 2-D and 3-D multiparticle thermofluid dynamic flow codes to examine a powerful volcanic blast that occurred on Montserrat in December 1997. On the basis of the simulations, we divide the blast into three phases: an initial burst phase that lasts roughly 5 s and involves rapid expansion of the gas-pyroclast mixture, a gravitational collapse phase that occurs when the erupted material fails to mix with sufficient air to form a buoyant column and thus collapses asymmetrically, and a PDC phase that is dominated by motion parallel to the ground surface and is influenced by topography. We vary key input parameters such as total gas energy and total solid mass to understand their influence on simulations, and we compare the simulations with independent field observations of damage and deposits, demonstrating that the models generally capture important large-scale features of the natural phenomenon. We also examine the 2-D and 3-D model results to estimate the flow Mach number and conclude that the range of damage sustained at villages on Montserrat can be reasonably explained by the spatial and temporal distribution of the dynamic pressure associated with subsonic PDCs.

High resolution seismic tomography imaging of Ireland with quarry blast data

Science.gov (United States)

Arroucau, P.; Lebedev, S.; Bean, C. J.; Grannell, J.

2017-12-01

Local earthquake tomography is a well established tool to image geological structure at depth. That technique, however, is difficult to apply in slowly deforming regions, where local earthquakes are typically rare and of small magnitude, resulting in sparse data sampling. The natural earthquake seismicity of Ireland is very low. That due to quarry and mining blasts, on the other hand, is high and homogeneously distributed. As a consequence, and thanks to the dense and nearly uniform coverage achieved in the past ten years by temporary and permanent broadband seismological stations, the quarry blasts offer an alternative approach for high resolution seismic imaging of the crust and uppermost mantle beneath Ireland. We detected about 1,500 quarry blasts in Ireland and Northern Ireland between 2011 and 2014, for which we manually picked more than 15,000 P- and 20,000 S-wave first arrival times. The anthropogenic, explosive origin of those events was unambiguously assessed based on location, occurrence time and waveform characteristics. Here, we present a preliminary 3D tomographic model obtained from the inversion of 3,800 P-wave arrival times associated with a subset of 500 events observed in 2011, using FMTOMO tomographic code. Forward modeling is performed with the Fast Marching Method (FMM) and the inverse problem is solved iteratively using a gradient-based subspace inversion scheme after careful selection of damping and smoothing regularization parameters. The results illuminate the geological structure of Ireland from deposit to crustal scale in unprecedented detail, as demonstrated by sensitivity analysis, source relocation with the 3D velocity model and comparisons with surface geology.

Divide and Conquer (DC BLAST: fast and easy BLAST execution within HPC environments

Directory of Open Access Journals (Sweden)

Won Cheol Yim

2017-06-01

Full Text Available Bioinformatics is currently faced with very large-scale data sets that lead to computational jobs, especially sequence similarity searches, that can take absurdly long times to run. For example, the National Center for Biotechnology Information (NCBI Basic Local Alignment Search Tool (BLAST and BLAST+ suite, which is by far the most widely used tool for rapid similarity searching among nucleic acid or amino acid sequences, is highly central processing unit (CPU intensive. While the BLAST suite of programs perform searches very rapidly, they have the potential to be accelerated. In recent years, distributed computing environments have become more widely accessible and used due to the increasing availability of high-performance computing (HPC systems. Therefore, simple solutions for data parallelization are needed to expedite BLAST and other sequence analysis tools. However, existing software for parallel sequence similarity searches often requires extensive computational experience and skill on the part of the user. In order to accelerate BLAST and other sequence analysis tools, Divide and Conquer BLAST (DCBLAST was developed to perform NCBI BLAST searches within a cluster, grid, or HPC environment by using a query sequence distribution approach. Scaling from one (1 to 256 CPU cores resulted in significant improvements in processing speed. Thus, DCBLAST dramatically accelerates the execution of BLAST searches using a simple, accessible, robust, and parallel approach. DCBLAST works across multiple nodes automatically and it overcomes the speed limitation of single-node BLAST programs. DCBLAST can be used on any HPC system, can take advantage of hundreds of nodes, and has no output limitations. This freely available tool simplifies distributed computation pipelines to facilitate the rapid discovery of sequence similarities between very large data sets.

Simulation tools for guided wave based structural health monitoring

Science.gov (United States)

Mesnil, Olivier; Imperiale, Alexandre; Demaldent, Edouard; Baronian, Vahan; Chapuis, Bastien

2018-04-01

Structural Health Monitoring (SHM) is a thematic derived from Non Destructive Evaluation (NDE) based on the integration of sensors onto or into a structure in order to monitor its health without disturbing its regular operating cycle. Guided wave based SHM relies on the propagation of guided waves in plate-like or extruded structures. Using piezoelectric transducers to generate and receive guided waves is one of the most widely accepted paradigms due to the low cost and low weight of those sensors. A wide range of techniques for flaw detection based on the aforementioned setup is available in the literature but very few of these techniques have found industrial applications yet. A major difficulty comes from the sensitivity of guided waves to a substantial number of parameters such as the temperature or geometrical singularities, making guided wave measurement difficult to analyze. In order to apply guided wave based SHM techniques to a wider spectrum of applications and to transfer those techniques to the industry, the CEA LIST develops novel numerical methods. These methods facilitate the evaluation of the robustness of SHM techniques for multiple applicative cases and ease the analysis of the influence of various parameters, such as sensors positioning or environmental conditions. The first numerical tool is the guided wave module integrated to the commercial software CIVA, relying on a hybrid modal-finite element formulation to compute the guided wave response of perturbations (cavities, flaws…) in extruded structures of arbitrary cross section such as rails or pipes. The second numerical tool is based on the spectral element method [2] and simulates guided waves in both isotropic (metals) and orthotropic (composites) plate like-structures. This tool is designed to match the widely accepted sparse piezoelectric transducer array SHM configuration in which each embedded sensor acts as both emitter and receiver of guided waves. This tool is under development and

Fundamental study on carbon composite iron ore hot briquette used as blast furnace burden

Energy Technology Data Exchange (ETDEWEB)

Chu, Man-sheng; Liu, Zheng-gen; Wang, Zhao-cai [Institute of Ferrous Metallurgy, Northeastern University, Shenyang (China); Yagi, Jun-ichiro [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University (Japan)

2011-05-15

Carbon composite iron ore hot briquette (CCB) is the product of fine iron ore and fine coal by hot briquetting process, which attracts more and more attention as a new type of ironmaking raw materials aiming to improve the operation efficiency and reduce the coke consumption of blast furnace. This paper is devoted to experimental study on metallurgical properties of CCB and numerical simulation of the BF operation with CCB charging. At first, the metallurgical properties of CCB, including cold crushing strength, RDI, RSI, reducibility, high temperature strength, and softening and dripping are experimentally tested and compared with the common burdens, which revealed that the CCB possesses the required metallurgical properties and is suitable to use as the blast furnace burden. Then, the effects of charging CCB on the dripping properties of comprehensive burdens are elucidated based on the experiments under simulated blast furnace conditions. The results showed that the maximum charging ratio of CCB in the iron burdens is 40%-50% for achieving appropriate dripping properties of the mixed burdens. Finally, a multi-fluid blast furnace model is used to simulate BF operation with CCB charging. According to model simulations, charging CCB will cause the temperature level to decreases in the furnace and the location of the cohesive zone shifts downward. On the other hand, the productivity tends to increase while coke rate and total reducing agent rate decrease, the heat efficiency improves remarkably and the operation performance of BF is effectively enhanced. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A numerical simulation of metallic cylindrical sandwich shells subjected to air blast loading

Directory of Open Access Journals (Sweden)

Lin Jing

Full Text Available The dynamic response of cylindrical sandwich shells with aluminum foam cores subjected to air blast loading was investigated numerically in this paper. According to KNR theory, the nonlinear compressibility of the air and finite shock conditions were taken into account in the finite element model. Numerical simulation results show that the compression strain, which plays a key role on energy absorption, increases approximately linearly with normalized impulse, and reduces with increasing relative density or the ratio of face-sheet thickness and core thickness. An increase of the impulse will delay the equalization of top and bottom face-sheet velocities of sandwich shell, but there is a maximum value in the studied bound. A limited study of weight optimization was carried out for sandwich shells with respect to the respective geometric parameters, including face-sheet thickness, core thickness and core relative density. These numerical results are of worth to theoretical prediction and engineering application of cellular metal sandwich structures.

Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines

DEFF Research Database (Denmark)

Kallesøe, Bjarne Skovmose

This report present results from the PSO project 2008-1-10092 entitled Aero-Hydro-Elastic Simulation Platform for Wave Energy Systems and floating Wind Turbines that deals with measurements, modelling and simulations of the world’s first combined wave and wind energy platform. The floating energy...

Numerical Simulation of Wave Propagation and Phase Transition of Tin under Shock-Wave Loading

International Nuclear Information System (INIS)

Hai-Feng, Song; Hai-Feng, Liu; Guang-Cai, Zhang; Yan-Hong, Zhao

2009-01-01

We undertake a numerical simulation of shock experiments on tin reported in the literature, by using a multiphase equation of state (MEOS) and a multiphase Steinberg Guinan (MSG) constitutive model for tin in the β, γ and liquid phases. In the MSG model, the Bauschinger effect is considered to better describe the unloading behavior. The phase diagram and Hugoniot of tin are calculated by MEOS, and they agree well with the experimental data. Combined with the MEOS and MSG models, hydrodynamic computer simulations are successful in reproducing the measured velocity profile of the shock wave experiment. Moreover, by analyzing the mass fraction contour as well as stress and temperature profiles of each phase for tin, we further discuss the complex behavior of tin under shock-wave loading. (condensed matter: structure, mechanical and thermal properties)

Particle simulation of intense electron cyclotron heating and beat-wave current drive

International Nuclear Information System (INIS)

Cohen, B.I.

1987-01-01

High-power free-electron lasers make new methods possible for heating plasmas and driving current in toroidal plasmas with electromagnetic waves. We have undertaken particle simulation studies with one and two dimensional, relativistic particle simulation codes of intense pulsed electron cyclotron heating and beat-wave current drive. The particle simulation methods here are conventional: the algorithms are time-centered, second-order-accurate, explicit, leap-frog difference schemes. The use of conventional methods restricts the range of space and time scales to be relatively compact in the problems addressed. Nevertheless, experimentally relevant simulations have been performed. 10 refs., 2 figs

An analysis of the heap construction by long hole blasting for in-situ leaching of blasted ore

International Nuclear Information System (INIS)

Yang Shijiao

1999-01-01

The author establishes specific requirements for heap construction by blasting on the basis of the mechanism for in situ leaching of blasted ore, analyses the feasibility of heap construction by long hole blasting, selection of the blast plan and the relevant technological problems, and gives a case of heap construction by long hole blasting in Renhua uranium mine

Simple simulation training system for short-wave radio station

Science.gov (United States)

Tan, Xianglin; Shao, Zhichao; Tu, Jianhua; Qu, Fuqi

2018-04-01

The short-wave radio station is a most important transmission equipment of our signal corps, but in the actual teaching process, which exist the phenomenon of fewer equipment and more students, making the students' short-wave radio operation and practice time is very limited. In order to solve the above problems, to carry out shortwave radio simple simulation training system development is very necessary. This project is developed by combining hardware and software to simulate the voice communication operation and signal principle of shortwave radio station, and can test the signal flow of shortwave radio station. The test results indicate that this system is simple operation, human-machine interface friendly and can improve teaching more efficiency.

Rock fragmentation control in opencast blasting

Directory of Open Access Journals (Sweden)

P.K. Singh

2016-04-01

Full Text Available The blasting operation plays a pivotal role in the overall economics of opencast mines. The blasting sub-system affects all the other associated sub-systems, i.e. loading, transport, crushing and milling operations. Fragmentation control through effective blast design and its effect on productivity are the challenging tasks for practicing blasting engineer due to inadequate knowledge of actual explosive energy released in the borehole, varying initiation practice in blast design and its effect on explosive energy release characteristic. This paper describes the result of a systematic study on the impact of blast design parameters on rock fragmentation at three mines in India. The mines use draglines and shovel–dumper combination for removal of overburden. Despite its pivotal role in controlling the overall economics of a mining operation, the expected blasting performance is often judged almost exclusively on the basis of poorly defined parameters such as powder factor and is often qualitative which results in very subjective assessment of blasting performance. Such an approach is very poor substitutes for accurate assessment of explosive and blasting performance. Ninety one blasts were conducted with varying blast designs and charging patterns, and their impacts on the rock fragmentation were documented. A high-speed camera was deployed to record the detonation sequences of the blasts. The efficiency of the loading machines was also correlated with the mean fragment size obtained from the fragmentation analyses.

Discrete event simulation of Maglev transport considering traffic waves

Directory of Open Access Journals (Sweden)

Moo Hyun Cha

2014-10-01

Full Text Available A magnetically levitated vehicle (Maglev system is under commercialization as a new transportation system in Korea. The Maglev is operated by an unmanned automatic control system. Therefore, the plan of train operation should be carefully established and validated in advance. In general, when making a train operation plan, statistically predicted traffic data is used. However, a traffic wave often occurs in real train service, and demand-driven simulation technology is required to review a train operation plan and service quality considering traffic waves. We propose a method and model to simulate Maglev operation considering continuous demand changes. For this purpose, we employed a discrete event model that is suitable for modeling the behavior of railway passenger transportation. We modeled the system hierarchically using discrete event system specification (DEVS formalism. In addition, through implementation and an experiment using the DEVSim++ simulation environment, we tested the feasibility of the proposed model. Our experimental results also verified that our demand-driven simulation technology can be used for a priori review of train operation plans and strategies.

An artificial generation of a few specific wave conditions: New simulator design and experimental performance

International Nuclear Information System (INIS)

Ramadan, A.; Mohamed, M.H.; Marzok, S.Y.; Montasser, O.A.; El Feky, A.; El Baz, A.R.

2014-01-01

In recent years, an amplified global awareness has led to a reawakening of interest in renewable energy technology. In an effort to reduce the worldwide dependence on fossil fuels, cleaner power generation methods are being sought in the field of solar, biomass, wind and wave energy. The importance of wave energy is increased in particular in some countries like UK, Portugal, Spain and Japan. A considerable progress has already been achieved in this field but the available technical designs are not adequate to develop reliable wave energy converters. Wave energy is the most available energy associated in water seas and oceans. Simultaneously, the wave energy has consisted of two types of energies: potential and kinetic energy. Therefore, many attempts have been applied to capture these energies. In the present work, a wave generator device has been designed and manufactured to simulate and generate the heaving motion of sea waves with different specification. A PC based electro-pneumatic control system was designed and implemented to individually control wave height, these heights are 3, 8, 16, 18 and 20 cm and different frequencies to generate these regular and irregular waves. - Highlights: • Wave energy is one of the most promising sources of renewable energy. • Most researchers built huge flume to simulate waves with large size and high budget. • A new simulator design for the direct and indirect wave energy is introduced. • The regular and irregular wave can be obtained for the new wave simulator. • This design is compact, flexible in terms amplitude, frequencies and high accuracy

DendroBLAST: approximate phylogenetic trees in the absence of multiple sequence alignments.

Science.gov (United States)

Kelly, Steven; Maini, Philip K

2013-01-01

The rapidly growing availability of genome information has created considerable demand for both fast and accurate phylogenetic inference algorithms. We present a novel method called DendroBLAST for reconstructing phylogenetic dendrograms/trees from protein sequences using BLAST. This method differs from other methods by incorporating a simple model of sequence evolution to test the effect of introducing sequence changes on the reliability of the bipartitions in the inferred tree. Using realistic simulated sequence data we demonstrate that this method produces phylogenetic trees that are more accurate than other commonly-used distance based methods though not as accurate as maximum likelihood methods from good quality multiple sequence alignments. In addition to tests on simulated data, we use DendroBLAST to generate input trees for a supertree reconstruction of the phylogeny of the Archaea. This independent analysis produces an approximate phylogeny of the Archaea that has both high precision and recall when compared to previously published analysis of the same dataset using conventional methods. Taken together these results demonstrate that approximate phylogenetic trees can be produced in the absence of multiple sequence alignments, and we propose that these trees will provide a platform for improving and informing downstream bioinformatic analysis. A web implementation of the DendroBLAST method is freely available for use at http://www.dendroblast.com/.

DendroBLAST: approximate phylogenetic trees in the absence of multiple sequence alignments.

Directory of Open Access Journals (Sweden)

Steven Kelly

Full Text Available The rapidly growing availability of genome information has created considerable demand for both fast and accurate phylogenetic inference algorithms. We present a novel method called DendroBLAST for reconstructing phylogenetic dendrograms/trees from protein sequences using BLAST. This method differs from other methods by incorporating a simple model of sequence evolution to test the effect of introducing sequence changes on the reliability of the bipartitions in the inferred tree. Using realistic simulated sequence data we demonstrate that this method produces phylogenetic trees that are more accurate than other commonly-used distance based methods though not as accurate as maximum likelihood methods from good quality multiple sequence alignments. In addition to tests on simulated data, we use DendroBLAST to generate input trees for a supertree reconstruction of the phylogeny of the Archaea. This independent analysis produces an approximate phylogeny of the Archaea that has both high precision and recall when compared to previously published analysis of the same dataset using conventional methods. Taken together these results demonstrate that approximate phylogenetic trees can be produced in the absence of multiple sequence alignments, and we propose that these trees will provide a platform for improving and informing downstream bioinformatic analysis. A web implementation of the DendroBLAST method is freely available for use at http://www.dendroblast.com/.

On the propagation and multiple reflections of a blast wave travelling through a dusty gas in a closed box

Science.gov (United States)

Lappa, Marcello; Drikakis, Dimitris; Kokkinakis, Ioannis

2017-03-01

This paper concerns the propagation of shock waves in an enclosure filled with dusty gas. The main motivation for this problem is to probe the effect on such dynamics of solid particles dispersed in the fluid medium. This subject, which has attracted so much attention over recent years given its important implications in the study of the structural stability of systems exposed to high-energy internal detonations, is approached here in the framework of a hybrid numerical two-way coupled Eulerian-Lagrangian methodology. In particular, insights are sought by considering a relatively simple archetypal setting corresponding to a shock wave originating from a small spherical region initialized on the basis of available analytic solutions. The response of the system is explored numerically with respect to several parameters, including the blast intensity (via the related value of the initial shock Mach number), the solid mass fraction (mass load), and the particle size (Stokes number). Results are presented in terms of pressure-load diagrams. Beyond practical applications, it is shown that a kaleidoscope of fascinating patterns is produced by the "triadic" relationships among multiple shock reflection events and particle-fluid and particle-wall interaction dynamics. These would be of great interest to researchers and scientists interested in fundamental problems relating to the general theory of pattern formation in complex nonlinear multiphase systems.

Numerical Simulation of Internal Waves in the Andaman Sea

Science.gov (United States)

Mohanty, Sachiko; Devendra Rao, Ambarukhana

2017-04-01

The interactions of barotropic tides with irregular bottom topography generate internal waves with high amplitude known as large-amplitude internal waves (LAIW) in the Andaman Sea. These waves are an important phenomena in the ocean due to their influence on the density structure and energy transfer into the region. These waves are also important in submarine acoustics, underwater navigation, offshore structures, ocean mixing, biogeochemical processes, etc. over the shelf-slope region. In the present study, energetics analysis of M2 internal tides over the Andaman Sea is carried out in detail by using a three-dimensional MIT general circulation ocean model (MITgcm). In-situ observations of temperature, conductivity and currents with high temporal resolution are used to validate the model simulations. From the spectral energy estimate of density, it is found that the peak estimate is associated with the semi-diurnal frequency at all the depths in both observations and model simulations. The baroclinic velocity characteristics, suggests that a multi-mode features of baroclinic tides are present at the buoy location. To understand the generation and propagation of internal tides over this region, energy flux and barotropic-to-baroclinic M2 tidal energy conversion rates are examined. The model simulation suggests that the internal tide is generated at multiple sites and propagate off of their respective generation sources. Most of the energy propagation in the Andaman Sea follows the 1000m isobath. The maximum horizontal kinetic energy follows the energy flux pattern over the domain and the available potential energy is found to be maximum in the north of the Andaman Sea.

Slamming Simulations in a Conditional Wave

DEFF Research Database (Denmark)

Seng, Sopheak; Jensen, Jørgen Juncher

2012-01-01

A study of slamming events in conditional waves is presented in this paper. The ship is sailing in head sea and the motion is solved for under the assumption of rigid body motion constrained to two degree-of-freedom i.e. heave and pitch. Based on a time domain non-linear strip theory most probable...... surface NS/VOF CFD simulations under the same wave conditions. In moderate seas and no occurrence of slamming the structural responses predicted by the methods agree well. When slamming occurs the strip theory overpredicts VBM but the peak values of VBM occurs at approximately the same time as predicted...... by the CFD method implying the possibility to use the more accurate CFD results to improve the estimation of slamming loads in the strip theory through a rational correction coefficient....

Plasma and wave properties downstream of Martian bow shock: Hybrid simulations and MAVEN observations

Science.gov (United States)

Dong, Chuanfei; Winske, Dan; Cowee, Misa; Bougher, Stephen W.; Andersson, Laila; Connerney, Jack; Epley, Jared; Ergun, Robert; McFadden, James P.; Ma, Yingjuan; Toth, Gabor; Curry, Shannon; Nagy, Andrew; Jakosky, Bruce

2015-04-01

Two-dimensional hybrid simulation codes are employed to investigate the kinetic properties of plasmas and waves downstream of the Martian bow shock. The simulations are two-dimensional in space but three dimensional in field and velocity components. Simulations show that ion cyclotron waves are generated by temperature anisotropy resulting from the reflected protons around the Martian bow shock. These proton cyclotron waves could propagate downward into the Martian ionosphere and are expected to heat the O+ layer peaked from 250 to 300 km due to the wave-particle interaction. The proton cyclotron wave heating is anticipated to be a significant source of energy into the thermosphere, which impacts atmospheric escape rates. The simulation results show that the specific dayside heating altitude depends on the Martian crustal field orientations, solar cycles and seasonal variations since both the cyclotron resonance condition and the non/sub-resonant stochastic heating threshold depend on the ambient magnetic field strength. The dayside magnetic field profiles for different crustal field orientation, solar cycle and seasonal variations are adopted from the BATS-R-US Mars multi-fluid MHD model. The simulation results, however, show that the heating of O+ via proton cyclotron wave resonant interaction is not likely in the relatively weak crustal field region, based on our simplified model. This indicates that either the drift motion resulted from the transport of ionospheric O+, or the non/sub-resonant stochastic heating mechanism are important to explain the heating of Martian O+ layer. We will investigate this further by comparing the simulation results with the available MAVEN data. These simulated ion cyclotron waves are important to explain the heating of Martian O+ layer and have significant implications for future observations.

The Mechanism and Application of Deep-Hole Precracking Blasting on Rockburst Prevention

Directory of Open Access Journals (Sweden)

Zhenhua Ouyang

2015-01-01

Full Text Available The mechanism of preventing rockburst through deep-hole precracking blasting was studied based on experimental test, numerical simulation, and field testing. The study results indicate that the deep-hole precracking could change the bursting proneness and stress state of coal-rock mass, thereby preventing the occurrence of rockburst. The bursting proneness of the whole composite structure could be weakened by the deep-hole precracking blasting. The change of stress state in the process of precracking blasting is achieved in two ways: (1 artificially break the roof apart, thus weakening the continuity of the roof strata, effectively inducing the roof caving while reducing its impact strength; and (2 the dynamic shattering and air pressure generated by the blasting can structurally change the properties of the coal-rock mass by mitigating the high stress generation and high elastic energy accumulation, thus breaking the conditions of energy transfer and rock burst occurrence.

Numerical Simulation of Freak Waves Based on the Four-Order Nonlinear Schr(o)dinger Equation

Institute of Scientific and Technical Information of China (English)

ZHANG Yun-qiu; ZHANG Ning-chuan; PEI Yu-guo

2007-01-01

A numerical wave model based on the modified four-order nonlinear Schrodinger (NLS) equation in deep water is developed to simulate freak waves. A standard split-step, pseudo-spectral method is used to solve NLS equation. The validation of the model is firstly verified, and then the simulation of freak waves is performed by changing sideband conditions. Results show that freak waves entirely consistent with the definition in the evolution of wave trains are obtained. The possible occurrence mechanism of freak waves is discussed and the relevant characteristics are also analyzed.

Wave fields simulation in difficult terrain using numerical grid method; Hyoko henka no aru chiiki deno suchi koshi wo mochiita hado simulation

Energy Technology Data Exchange (ETDEWEB)

Jung, W; Ogawa, T [Yokohama National University, Yokohama (Japan); Tamagawa, T; Matsuoka, T [Japan Petroleum Exploration Corp., Tokyo (Japan)

1997-10-22

This paper describes that a high-accuracy simulation can be made on seismic exploration by using the numerical grid method. When applying a wave field simulation using the difference calculus to an area subjected to seismic exploration, a problem occurs as to how a boundary of the velocity structure including the ground surface should be dealt with. Simply applying grids to a boundary changing continuously makes accuracy of the simulation worse. The difference calculus using a numerical grid is a method to solve the problem by imaging a certain region into a rectangular region through use of variable conversion, which can impose the boundary condition more accurately. The wave field simulation was carried out on a simple two-layer inclined structure and a two-layer waved structure. It was revealed that amplitudes of direct waves and reflection waves are disturbed in the case where no numerical grid method is applied, and the amplitudes are more disperse in the reflection waves than those obtained by using the numerical grid method. 7 refs., 10 figs.

Wound Ballistics Modeling for Blast Loading Blunt Force Impact and Projectile Penetration

Energy Technology Data Exchange (ETDEWEB)

Taylor, Paul A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Candice Frances [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-01

Light body armor development for the warfighter is based on trial-and-error testing of prototype designs against ballistic projectiles. Torso armor testing against blast is virtually nonexistent but necessary to ensure adequate protection against injury to the heart and lungs. In this report, we discuss the development of a high-fidelity human torso model, it's merging with the existing Sandia Human Head-Neck Model, and development of the modeling & simulation (M&S) capabilities necessary to simulate wound injury scenarios. Using the new Sandia Human Torso Model, we demonstrate the advantage of virtual simulation in the investigation of wound injury as it relates to the warfighter experience. We present the results of virtual simulations of blast loading and ballistic projectile impact to the tors o with and without notional protective armor. In this manner, we demonstrate the ad vantages of applying a modeling and simulation approach to the investigation of wound injury and relative merit assessments of protective body armor without the need for trial-and-error testing.

Numerical Simulation of Cylindrical Solitary Waves in Periodic Media

KAUST Repository

Quezada de Luna, Manuel; Ketcheson, David I.

2013-01-01

We study the behavior of nonlinear waves in a two-dimensional medium with density and stress relation that vary periodically in space. Efficient approximate Riemann solvers are developed for the corresponding variable-coefficient first-order hyperbolic system. We present direct numerical simulations of this multiscale problem, focused on the propagation of a single localized perturbation in media with strongly varying impedance. For the conditions studied, we find little evidence of shock formation. Instead, solutions consist primarily of solitary waves. These solitary waves are observed to be stable over long times and to interact in a manner approximately like solitons. The system considered has no dispersive terms; these solitary waves arise due to the material heterogeneity, which leads to strong reflections and effective dispersion.

Numerical Simulation of Cylindrical Solitary Waves in Periodic Media

KAUST Repository

Quezada de Luna, Manuel

2013-07-14

We study the behavior of nonlinear waves in a two-dimensional medium with density and stress relation that vary periodically in space. Efficient approximate Riemann solvers are developed for the corresponding variable-coefficient first-order hyperbolic system. We present direct numerical simulations of this multiscale problem, focused on the propagation of a single localized perturbation in media with strongly varying impedance. For the conditions studied, we find little evidence of shock formation. Instead, solutions consist primarily of solitary waves. These solitary waves are observed to be stable over long times and to interact in a manner approximately like solitons. The system considered has no dispersive terms; these solitary waves arise due to the material heterogeneity, which leads to strong reflections and effective dispersion.

Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury

Directory of Open Access Journals (Sweden)

Ming-Xiong Huang

2014-01-01

Full Text Available Traumatic brain injury (TBI is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz that can be measured and localized by resting-state magnetoencephalography (MEG. In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes, our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes, blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

Wide-band slow-wave systems simulation and applications

CERN Document Server

Staras, Stanislovas

2012-01-01

The field of electromagnetics has seen considerable advances in recent years, based on the wide applications of numerical methods for investigating electromagnetic fields, microwaves, and other devices. Wide-Band Slow-Wave Systems: Simulation and Applications presents new technical solutions and research results for the analysis, synthesis, and design of slow-wave structures for modern electronic devices with super-wide pass-bands. It makes available, for the first time in English, significant research from the past 20 years that was previously published only in Russian and Lithuanian. The aut

Simulation and Analysis of Converging Shock Wave Test Problems

Energy Technology Data Exchange (ETDEWEB)

Ramsey, Scott D. [Los Alamos National Laboratory; Shashkov, Mikhail J. [Los Alamos National Laboratory

2012-06-21

Results and analysis pertaining to the simulation of the Guderley converging shock wave test problem (and associated code verification hydrodynamics test problems involving converging shock waves) in the LANL ASC radiation-hydrodynamics code xRAGE are presented. One-dimensional (1D) spherical and two-dimensional (2D) axi-symmetric geometric setups are utilized and evaluated in this study, as is an instantiation of the xRAGE adaptive mesh refinement capability. For the 2D simulations, a 'Surrogate Guderley' test problem is developed and used to obviate subtleties inherent to the true Guderley solution's initialization on a square grid, while still maintaining a high degree of fidelity to the original problem, and minimally straining the general credibility of associated analysis and conclusions.

An FDTD-based computer simulation platform for shock wave propagation in electrohydraulic lithotripsy.

Science.gov (United States)

Yılmaz, Bülent; Çiftçi, Emre

2013-06-01

Extracorporeal Shock Wave Lithotripsy (ESWL) is based on disintegration of the kidney stone by delivering high-energy shock waves that are created outside the body and transmitted through the skin and body tissues. Nowadays high-energy shock waves are also used in orthopedic operations and investigated to be used in the treatment of myocardial infarction and cancer. Because of these new application areas novel lithotriptor designs are needed for different kinds of treatment strategies. In this study our aim was to develop a versatile computer simulation environment which would give the device designers working on various medical applications that use shock wave principle a substantial amount of flexibility while testing the effects of new parameters such as reflector size, material properties of the medium, water temperature, and different clinical scenarios. For this purpose, we created a finite-difference time-domain (FDTD)-based computational model in which most of the physical system parameters were defined as an input and/or as a variable in the simulations. We constructed a realistic computational model of a commercial electrohydraulic lithotriptor and optimized our simulation program using the results that were obtained by the manufacturer in an experimental setup. We, then, compared the simulation results with the results from an experimental setup in which oxygen level in water was varied. Finally, we studied the effects of changing the input parameters like ellipsoid size and material, temperature change in the wave propagation media, and shock wave source point misalignment. The simulation results were consistent with the experimental results and expected effects of variation in physical parameters of the system. The results of this study encourage further investigation and provide adequate evidence that the numerical modeling of a shock wave therapy system is feasible and can provide a practical means to test novel ideas in new device design procedures

Human Injury Criteria for Underwater Blasts.

Directory of Open Access Journals (Sweden)

Rachel M Lance

Full Text Available Underwater blasts propagate further and injure more readily than equivalent air blasts. Development of effective personal protection and countermeasures, however, requires knowledge of the currently unknown human tolerance to underwater blast. Current guidelines for prevention of underwater blast injury are not based on any organized injury risk assessment, human data or experimental data. The goal of this study was to derive injury risk assessments for underwater blast using well-characterized human underwater blast exposures in the open literature. The human injury dataset was compiled using 34 case reports on underwater blast exposure to 475 personnel, dating as early as 1916. Using severity ratings, computational reconstructions of the blasts, and survival information from a final set of 262 human exposures, injury risk models were developed for both injury severity and risk of fatality as functions of blast impulse and blast peak overpressure. Based on these human data, we found that the 50% risk of fatality from underwater blast occurred at 302±16 kPa-ms impulse. Conservatively, there is a 20% risk of pulmonary injury at a kilometer from a 20 kg charge. From a clinical point of view, this new injury risk model emphasizes the large distances possible for potential pulmonary and gut injuries in water compared with air. This risk value is the first impulse-based fatality risk calculated from human data. The large-scale inconsistency between the blast exposures in the case reports and the guidelines available in the literature prior to this study further underscored the need for this new guideline derived from the unique dataset of actual injuries in this study.

Blasting agents and initiation systems

Energy Technology Data Exchange (ETDEWEB)

Fiscor, S.

2000-01-01

Although blasting differs between and within each industry, as a whole, the mines and quarries are making a shift from a purely ammonium nitrate/fuel oil (ANFO) mixture to a blend of emulsion and ANFO on a straight emulsion. Non-electric (shock tube) initiation systems have provided a viable alternative to the electric detonator (blasting cap). Explosives manufacturers are seeing their roles changes to being blasting contractors or consultants rather than just suppliers. The article discusses these trends and gives examples of typical blasting techniques and amounts of blasting agent used at large USA surface coal mines. Electric caps are still used in blasting underground coal. The Ensign Bickford Co. (EBCo) is developing electronic detonators and has been field testing an electronic initiator, the DIGIDET detonator, for the last four years. When commercially available, electronic detonators will be accurate but will come with a hefty price tag. 2 photos.

Analog quantum simulation of gravitational waves in a Bose-Einstein condensate

International Nuclear Information System (INIS)

Bravo, Tupac; Sabin, Carlos; Fuentes, Ivette

2015-01-01

We show how to vary the physical properties of a Bose-Einstein condensate (BEC) in order to mimic an effective gravitational-wave spacetime. In particular, we focus in the simulation of the recently discovered creation of particles by a real spacetime distortion in box-type traps. We show that, by modulating the speed of sound in the BEC, the phonons experience the effects of a simulated spacetime ripple with experimentally amenable parameters. These results will inform the experimental programme of gravitational wave astronomy with cold atoms. (orig.)

Analog quantum simulation of gravitational waves in a Bose-Einstein condensate

Energy Technology Data Exchange (ETDEWEB)

Bravo, Tupac; Sabin, Carlos; Fuentes, Ivette [University of Nottingham, School of Mathematical Sciences, Nottingham (United Kingdom)

2015-01-04

We show how to vary the physical properties of a Bose-Einstein condensate (BEC) in order to mimic an effective gravitational-wave spacetime. In particular, we focus in the simulation of the recently discovered creation of particles by a real spacetime distortion in box-type traps. We show that, by modulating the speed of sound in the BEC, the phonons experience the effects of a simulated spacetime ripple with experimentally amenable parameters. These results will inform the experimental programme of gravitational wave astronomy with cold atoms. (orig.)

An optimization method of relativistic backward wave oscillator using particle simulation and genetic algorithms

Energy Technology Data Exchange (ETDEWEB)

Chen, Zaigao; Wang, Jianguo [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Northwest Institute of Nuclear Technology, P.O. Box 69-12, Xi' an, Shaanxi 710024 (China); Wang, Yue; Qiao, Hailiang; Zhang, Dianhui [Northwest Institute of Nuclear Technology, P.O. Box 69-12, Xi' an, Shaanxi 710024 (China); Guo, Weijie [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)

2013-11-15

Optimal design method of high-power microwave source using particle simulation and parallel genetic algorithms is presented in this paper. The output power, simulated by the fully electromagnetic particle simulation code UNIPIC, of the high-power microwave device is given as the fitness function, and the float-encoding genetic algorithms are used to optimize the high-power microwave devices. Using this method, we encode the heights of non-uniform slow wave structure in the relativistic backward wave oscillators (RBWO), and optimize the parameters on massively parallel processors. Simulation results demonstrate that we can obtain the optimal parameters of non-uniform slow wave structure in the RBWO, and the output microwave power enhances 52.6% after the device is optimized.

Computational Fluid Dynamics Application to Gun Muzzle Blast - A Validation Case Study

National Research Council Canada - National Science Library

Cler, Daniel

2003-01-01

...) simulations of these flow-fields a viable alternative. Techniques and specialized CFD codes are being developed in order to properly model the unsteady, very high-pressure flows of gun muzzle blast...

Low Complexity V-BLAST MIMO-OFDM Detector by Successive Iterations Reduction

Directory of Open Access Journals (Sweden)

AHMED, K.

2015-02-01

Full Text Available V-BLAST detection method suffers large computational complexity due to its successive detection of symbols. In this paper, we propose a modified V-BLAST algorithm to decrease the computational complexity by reducing the number of detection iterations required in MIMO communication systems. We begin by showing the existence of a maximum number of iterations, beyond which, no significant improvement is obtained. We establish a criterion for the number of maximum effective iterations. We propose a modified algorithm that uses the measured SNR to dynamically set the number of iterations to achieve an acceptable bit-error rate. Then, we replace the feedback algorithm with an approximate linear function to reduce the complexity. Simulations show that significant reduction in computational complexity is achieved compared to the ordinary V-BLAST, while maintaining a good BER performance.

Nodal wear model: corrosion in carbon blast furnace hearths

International Nuclear Information System (INIS)

Verdeja, L. F.; Gonzalez, R.; Alfonso, A.; Barbes, M. F.

2003-01-01

Criteria developed for the Nodal Wear Model (NWM) were applied to estimate the shape of the corrosion profiles that a blast furnace hearth may acquire during its campaign. Taking into account design of the hearth, the boundary conditions, the characteristics of the refractory materials used and the operation conditions of the blast furnace, simulation of wear profiles with central well, mushroom and elephant foot shape were accomplished. The foundations of the NWM are constructed considering that the corrosion of the refractory is a function of the temperature present at each point (node) of the liquid metal-refractory interface and the corresponding physical and chemical characteristics of the corrosive fluid. (Author) 31 refs

Computational simulations of the interaction of water waves with pitching flap-type ocean wave energy converters

Science.gov (United States)

Pathak, Ashish; Raessi, Mehdi

2016-11-01

Using an in-house computational framework, we have studied the interaction of water waves with pitching flap-type ocean wave energy converters (WECs). The computational framework solves the full 3D Navier-Stokes equations and captures important effects, including the fluid-solid interaction, the nonlinear and viscous effects. The results of the computational tool, is first compared against the experimental data on the response of a flap-type WEC in a wave tank, and excellent agreement is demonstrated. Further simulations at the model and prototype scales are presented to assess the validity of the Froude scaling. The simulations are used to address some important questions, such as the validity range of common WEC modeling approaches that rely heavily on the Froude scaling and the inviscid potential flow theory. Additionally, the simulations examine the role of the Keulegan-Carpenter (KC) number, which is often used as a measure of relative importance of viscous drag on bodies exposed to oscillating flows. The performance of the flap-type WECs is investigated at various KC numbers to establish the relationship between the viscous drag and KC number for such geometry. That is of significant importance because such relationship only exists for simple geometries, e.g., a cylinder. Support from the National Science Foundation is gratefully acknowledged.

DYNAMIC TIME HISTORY ANALYSIS OF BLAST RESISTANT DOOR USING BLAST LOAD MODELED AS IMPACT LOAD

Directory of Open Access Journals (Sweden)

Y. A. Pranata

2012-06-01

Full Text Available A blast resistant single door was designed to withstand a 0.91 bar blast pressure and 44 ms blast duration. The analysis was done using Dynamic Time History Analysis using Blast Load modeled as Impact Load for given duration. The material properties used have been modified to accommodate dynamic effects. The analysis was done using dynamic finite element method (fem for time of the blast duration, and the maximum/minimum internal forces and displacement were taken from the time history output, in order to know the behavior under blast load and estimate the safety margin of the door. Results obtained from this research indicated that the maximum z-displacement is 1.709 mm, while in the term of serviceability, the permitted is 25 mm. The maximum reaction force is 73,960 N, while the maximum anchor capacity is 82,069 N. On blast condition, the maximum frame stress is 71.71 MPa, the maximum hinge shear stress is 45.28 MPa. While on rebound condition, the maximum frame stress is 172.11 MPa, the maximum hinge shear stress is 29.46 MPa. The maximum door edge rotation is 0.44 degree, which is not exceed the permitted boundary (1.2 degree. Keywords: Dynamic time history, blast resistant door, single door, finite element method.

Concepts and strategies for clinical management of blast-induced traumatic brain injury and posttraumatic stress disorder.

Science.gov (United States)

Chen, Yun; Huang, Wei; Constantini, Shlomi

2013-01-01

After exposure of the human body to blast, kinetic energy of the blast shock waves might be transferred into hydraulic energy in the cardiovascular system to cause a rapid physical movement or displacement of blood (a volumetric blood surge). The volumetric blood surge moves through blood vessels from the high-pressure body cavity to the low-pressure cranial cavity, causing damage to tiny cerebral blood vessels and the blood-brain barrier (BBB). Large-scale cerebrovascular insults and BBB damage that occur globally throughout the brain may be the main causes of non-impact, blast-induced brain injuries, including the spectrum of traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). The volumetric blood surge may be a major contributor not only to blast-induced brain injuries resulting from physical trauma, but may also be the trigger to psychiatric disorders resulting from emotional and psychological trauma. Clinical imaging technologies, which are able to detect tiny cerebrovascular insults, changes in blood flow, and cerebral edema, may help diagnose both TBI and PTSD in the victims exposed to blasts. Potentially, prompt medical treatment aiming at prevention of secondary neuronal damage may slow down or even block the cascade of events that lead to progressive neuronal damage and subsequent long-term neurological and psychiatric impairment.

CIMI simulations with newly developed multiparameter chorus and plasmaspheric hiss wave models

Science.gov (United States)

Aryan, Homayon; Sibeck, David G.; Kang, Suk-Bin; Balikhin, Michael A.; Fok, Mei-Ching; Agapitov, Oleksiy; Komar, Colin M.; Kanekal, Shrikanth G.; Nagai, Tsugunobu

2017-09-01

Numerical simulation studies of the Earth's radiation belts are important to understand the acceleration and loss of energetic electrons. The Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model considers the effects of the ring current and plasmasphere on the radiation belts to obtain plausible results. The CIMI model incorporates pitch angle, energy, and cross diffusion of electrons, due to chorus and plasmaspheric hiss waves. These parameters are calculated using statistical wave distribution models of chorus and plasmaspheric hiss amplitudes. However, currently, these wave distribution models are based only on a single-parameter, geomagnetic index (AE) and could potentially underestimate the wave amplitudes. Here we incorporate recently developed multiparameter chorus and plasmaspheric hiss wave models based on geomagnetic index and solar wind parameters. We then perform CIMI simulations for two geomagnetic storms and compare the flux enhancement of MeV electrons with data from the Van Allen Probes and Akebono satellites. We show that the relativistic electron fluxes calculated with multiparameter wave models resemble the observations more accurately than the relativistic electron fluxes calculated with single-parameter wave models. This indicates that wave models based on a combination of geomagnetic index and solar wind parameters are more effective as inputs to radiation belt models.

NCBI BLAST+ integrated into Galaxy.

Science.gov (United States)

Cock, Peter J A; Chilton, John M; Grüning, Björn; Johnson, James E; Soranzo, Nicola

2015-01-01

The NCBI BLAST suite has become ubiquitous in modern molecular biology and is used for small tasks such as checking capillary sequencing results of single PCR products, genome annotation or even larger scale pan-genome analyses. For early adopters of the Galaxy web-based biomedical data analysis platform, integrating BLAST into Galaxy was a natural step for sequence comparison workflows. The command line NCBI BLAST+ tool suite was wrapped for use within Galaxy. Appropriate datatypes were defined as needed. The integration of the BLAST+ tool suite into Galaxy has the goal of making common BLAST tasks easy and advanced tasks possible. This project is an informal international collaborative effort, and is deployed and used on Galaxy servers worldwide. Several examples of applications are described here.

HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

International Nuclear Information System (INIS)

McPhee, William S.

1999-01-01

The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and

Simulation study on cross polarization scattering of ultrashort-pulse electromagnetic waves

International Nuclear Information System (INIS)

Katsuragawa, Naoki; Hojo, Hitoshi; Mase, Atushi

1996-11-01

Simulation study on cross polarization scattering of ultrashort-pulse electromagnetic waves due to magnetic fluctuations is presented. One-dimensional coupled wave equations for the ordinary and extraordinary modes are solved for incident unipolar sub-cycle pulses in an inhomogeneous magnetized plasma. It is shown that the peak frequencies in the frequency-spectral signals of the mode-converted reflected waves are determined from the Bragg resonance condition in the wave numbers of the ordinary mode, the extraordinary mode and the magnetic fluctuations for relatively short-wavelength localized magnetic fluctuations. (author)

Simulations for design and reconstruction of breaking waves in a wavetank

NARCIS (Netherlands)

Kurnia, Ruddy; van den Munckhof, T.; Poot, C.P.; Naaijen, P.; Huijsmans, R.H.M.; van Groesen, Embrecht W.C.

To determine forces on fixed and flexible structures such as wind mills and oil platforms, experiments in wave tanks are useful to investigate the impacts in various types of environmental waves. In this paper we show that the use of an efficient simulation code can optimize the experiments by

Enhancements and Analysis of CTH Software for Underbody Blast

Science.gov (United States)

2013-02-01

authors expressed herein do not necessarily state or reflect those of the United States Government or the DoD, and shall not be used for advertising or...Trembelay, J., “Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles,” 7th International LS-DYNA Users Conference

Thermal valorisation of automobile shredder residue: injection in blast furnace.

Science.gov (United States)

Mirabile, Daphne; Pistelli, Maria Ilaria; Marchesini, Marina; Falciani, Roberta; Chiappelli, Lisa

2002-01-01

Wastes with residual heating value, according to the trend of the world legislation, could be thermally reused. The present study is conducted to verify the possibility of thermal valorisation of a waste, denominated fluff, by injection in blast furnace. The fluff, arising from the automobile shredder operations, is a waste characterised by a high organic matrix and is potentially dangerous due to the heavy metals, oils filter and halogenated plastics content. The first step of the work is the chemical, physical and toxicological characterisation of this material. Then the fluff injection in a blast furnace tuyere is theoretically analysed with a mathematical model. Finally, experimental trials are conducted in a pilot plant, simulating the most important part of the blast furnace: the raceway, in order to analyse process and industrial aspects. In view of an industrial application a first economical evaluation is carried out on the basis of model and experimental results.

Lamb wave propagation modelling and simulation using parallel processing architecture and graphical cards

International Nuclear Information System (INIS)

Paćko, P; Bielak, T; Staszewski, W J; Uhl, T; Spencer, A B; Worden, K

2012-01-01

This paper demonstrates new parallel computation technology and an implementation for Lamb wave propagation modelling in complex structures. A graphical processing unit (GPU) and computer unified device architecture (CUDA), available in low-cost graphical cards in standard PCs, are used for Lamb wave propagation numerical simulations. The local interaction simulation approach (LISA) wave propagation algorithm has been implemented as an example. Other algorithms suitable for parallel discretization can also be used in practice. The method is illustrated using examples related to damage detection. The results demonstrate good accuracy and effective computational performance of very large models. The wave propagation modelling presented in the paper can be used in many practical applications of science and engineering. (paper)

Simulation of ultrasonic surface waves with multi-Gaussian and point source beam models

International Nuclear Information System (INIS)

Zhao, Xinyu; Schmerr, Lester W. Jr.; Li, Xiongbing; Sedov, Alexander

2014-01-01

In the past decade, multi-Gaussian beam models have been developed to solve many complicated bulk wave propagation problems. However, to date those models have not been extended to simulate the generation of Rayleigh waves. Here we will combine Gaussian beams with an explicit high frequency expression for the Rayleigh wave Green function to produce a three-dimensional multi-Gaussian beam model for the fields radiated from an angle beam transducer mounted on a solid wedge. Simulation results obtained with this model are compared to those of a point source model. It is shown that the multi-Gaussian surface wave beam model agrees well with the point source model while being computationally much more efficient

Fluid-structure interaction dynamic simulation of spring-loaded pressure relief valves under seismic wave

Science.gov (United States)

Lv, Dongwei; Zhang, Jian; Yu, Xinhai

2018-05-01

In this paper, a fluid-structure interaction dynamic simulation method of spring-loaded pressure relief valve was established. The dynamic performances of the fluid regions and the stress and strain of the structure regions were calculated at the same time by accurately setting up the contact pairs between the solid parts and the coupling surfaces between the fluid regions and the structure regions. A two way fluid-structure interaction dynamic simulation of a simplified pressure relief valve model was carried out. The influence of vertical sinusoidal seismic waves on the performance of the pressure relief valve was preliminarily investigated by loading sine waves. Under vertical seismic waves, the pressure relief valve will flutter, and the reseating pressure was affected by the amplitude and frequency of the seismic waves. This simulation method of the pressure relief valve under vertical seismic waves can provide effective means for investigating the seismic performances of the valves, and make up for the shortcomings of the experiment.

OSSIM wave-optics toolbox and its use to simulate AEOS

Science.gov (United States)

Smith, Carey A.; Forgham, James L.; Jones, Bruce W.; Jones, Kenneth D.

2001-12-01

OSSim (Optical System Simulation) is a simulation toolbox of optical and processing components. By using full wave-optics in the time-domain, OSSim simulates diffractive effects and control loop interactions missed by simpler analyses. OSSim also models the atmosphere, with user customizable turbulence strength, wind, and slew. This paper first presents 2 introductory examples: a simple 2-lens imaging system and a simple tilt-control system. Then it presents a simulation of the 3.67-meter AEOS (Advanced Electro-Optics System) telescope on Maui. The OSSim simulation agrees well with the AEOS experimental results.

Evaluation of refractory lining wear of Companhia Siderurgica Nacional (CSN) blast furnaces

International Nuclear Information System (INIS)

Santos, N.J. dos; Mello, A.H.B. de; Pereira, C.L.; Paula Sarkis, D. de; Martins Filho, D.I.; Banados Perez, H.E.; Carvalho, G.; Daltro, T.F.L.

1984-01-01

The blast furnace refractory linings are submitted to unfavourable conditions such as alkalis attack, temperature, top pressure, abrasion and so forth... After studies on distribution and installation of radioactive sources with low activities in the refractory lining, it was possible to develop a new technique of thickness evaluation and attendance of wearing in the furnace lining. The viability analysis, simulated laboratory tests, localization, identification, installations and periodical measurements of the radioactive sources are described, as well the results obtained on the present campaign of CSN Blast Furnaces. (Author) [pt

Numerical simulation of multi-directional random wave transformation in a yacht port

Science.gov (United States)

Ji, Qiaoling; Dong, Sheng; Zhao, Xizeng; Zhang, Guowei

2012-09-01

This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.

On the adequacy of numerical codes for the simulation of vapour cloud explosions

International Nuclear Information System (INIS)

Wingerden, G.J.M.v.; Berg, A.C.v.d.

1984-01-01

Three spherically symmetric blast simulation codes have been evaluated: a low-flame-speed model (Piston model) and two gasdynamic blast simulation codes (BLAST and CLOUD). Self-similar flow fields in front of constant velocity flames and large- and small-scale spherically symmetric explosions experiments were simulated. The Piston model can be used for the simulation of spherically symmetric explosions at flame speeds -1 whereas BLAST and CLOUD are adequate for flame speeds exceeding 100 ms -1 . An adapted Piston code has been investigated with respect to the capability of simulating blast due to explosions of pancake-shaped clouds. Comparison to an acoustic approach showed that the Piston model can be regarded as an acoustic model with the possibility of handling every imaginable flame path. The research was part of the indirect action research programme on LWR Safety of the Commission of the European Communities. (project 12B, contract 008 SRN)

Blast-induced traumatic brain injury: a new trend of blast injury research.

Science.gov (United States)

Zhao, Yan; Wang, Zheng-Guo

2015-01-01

Blast injury has become the major life- and function-threatening injuries in recent warfares. There is increased research interest in the mental disorders caused by blast-induced traumatic brain injury (bTBI), which has been proved as one of the "signature wounds" in modern battlefield. We reviewed the recent progresses in bTBI-related researches and concluded that the new era of blast injury research has shifted from the traditional physical impairments to cognitive dysfunctional/mental disorders that are proved to be more related to the outcome of combat casualty care.

Monte-Carlo Orbit/Full Wave Simulation of Fast Alfven Wave (FW) Damping on Resonant Ions in Tokamaks

International Nuclear Information System (INIS)

Choi, M.; Chan, V.S.; Pinsker, R.I.; Tang, V.; Bonoli, P.; Wright, J.

2005-01-01

To simulate the resonant interaction of fast Alfven wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement

Blast management

OpenAIRE

Shouraki, Mohammad Kargar; Naserkheil, Ali Asghar

2011-01-01

Blast Management (BM) is composed of the combination of human resources management (HRM) principles and concepts and various methods of quality management (QM) with a financial approach. BM is made up of three aspects: hard, soft and concept and BLAST means an explosive shift in organization's mindset and thought and rapid action against it. The first aspect, hard, includes a set of managerial toots and philosophies to improve the quality and productivity with a financial approach.

Visualizing the phenomena of wave interference, phase-shifting and polarization by interactive computer simulations

Science.gov (United States)

Rivera-Ortega, Uriel; Dirckx, Joris

2015-09-01

In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.

Simulation of Irregular Waves and Wave Induced Loads on Wind Power Plants in Shallow Water

Energy Technology Data Exchange (ETDEWEB)

Trumars, Jenny [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Water Environment Transport

2004-05-01

The essay gives a short introduction to waves and discusses the problem with non-linear waves in shallow water and how they effect an offshore wind energy converter. The focus is on the realisation of non-linear waves in the time domain from short-term statistics in the form of a variance density spectrum of the wave elevation. For this purpose the wave transformation from deep water to the near to shore site of a wind energy farm at Bockstigen has been calculated with the use of SWAN (Simulating Waves Near Shore). The result is a wave spectrum, which can be used as input to the realisation. The realisation of waves is done by perturbation theory to the first and second-order. The properties calculated are the wave elevation, water particle velocity and acceleration. The wave heights from the second order perturbation equations are higher than those from the first order perturbation equations. This is also the case for the water particle kinematics. The increase of variance is significant between the first order and the second order realisation. The calculated wave elevation exhibits non-linear features as the peaks become sharper and the troughs flatter. The resulting forces are calculated using Morison's equation. For second order force and base moment there is an increase in the maximum values. The force and base moment are largest approximately at the zero up and down crossing of the wave elevation. This indicates an inertia dominated wave load. So far the flexibility and the response of the structure have not been taken into account. They are, however, of vital importance. For verification of the wave model the results will later on be compared with measurements at Bockstigen off the coast of Gotland in the Baltic Sea.

Wave-Kinetic Simulations of the Nonlinear Generation of Electromagnetic VLF Waves through Velocity Ring Instabilities

Science.gov (United States)

Ganguli, G.; Crabtree, C. E.; Rudakov, L.; Mithaiwala, M.

2014-12-01

Velocity ring instabilities are a common naturally occuring magnetospheric phenomenon that can also be generated by man made ionospheric experiments. These instabilities are known to generate lower-hybrid waves, which generally cannot propagte out of the source region. However, nonlinear wave physics can convert these linearly driven electrostatic lower-hybrid waves into electromagnetic waves that can escape the source region. These nonlinearly generated waves can be an important source of VLF turbulence that controls the trapped electron lifetime in the radiation belts. We develop numerical solutions to the wave-kinetic equation in a periodic box including the effects of nonlinear (NL) scattering (nonlinear Landau damping) of Lower-hybrid waves giving the evolution of the wave-spectra in wavenumber space. Simultaneously we solve the particle diffusion equation of both the background plasma particles and the ring ions, due to both linear and nonlinear Landau resonances. At initial times for cold ring ions, an electrostatic beam mode is excited, while the kinetic mode is stable. As the instability progresses the ring ions heat, the beam mode is stabilized, and the kinetic mode destabilizes. When the amplitude of the waves becomes sufficient the lower-hybrid waves are scattered (by either nearly unmagnetized ions or magnetized electrons) into electromagnetic magnetosonic waves [Ganguli et al 2010]. The effect of NL scattering is to limit the amplitude of the waves, slowing down the quasilinear relaxation time and ultimately allowing more energy from the ring to be liberated into waves [Mithaiwala et al. 2011]. The effects of convection out of the instability region are modeled, additionally limiting the amplitude of the waves, allowing further energy to be liberated from the ring [Scales et al., 2012]. Results are compared to recent 3D PIC simulations [Winske and Duaghton 2012].

Simulating three dimensional wave run-up over breakwaters covered by antifer units

Science.gov (United States)

Najafi-Jilani, A.; Niri, M. Zakiri; Naderi, Nader

2014-06-01

The paper presents the numerical analysis of wave run-up over rubble-mound breakwaters covered by antifer units using a technique integrating Computer-Aided Design (CAD) and Computational Fluid Dynamics (CFD) software. Direct application of Navier-Stokes equations within armour blocks, is used to provide a more reliable approach to simulate wave run-up over breakwaters. A well-tested Reynolds-averaged Navier-Stokes (RANS) Volume of Fluid (VOF) code (Flow-3D) was adopted for CFD computations. The computed results were compared with experimental data to check the validity of the model. Numerical results showed that the direct three dimensional (3D) simulation method can deliver accurate results for wave run-up over rubble mound breakwaters. The results showed that the placement pattern of antifer units had a great impact on values of wave run-up so that by changing the placement pattern from regular to double pyramid can reduce the wave run-up by approximately 30%. Analysis was done to investigate the influences of surface roughness, energy dissipation in the pores of the armour layer and reduced wave run-up due to inflow into the armour and stone layer.

Simulating three dimensional wave run-up over breakwaters covered by antifer units

Directory of Open Access Journals (Sweden)

A. Najafi-Jilani

2014-06-01

Full Text Available The paper presents the numerical analysis of wave run-up over rubble-mound breakwaters covered by antifer units using a technique integrating Computer-Aided Design (CAD and Computational Fluid Dynamics (CFD software. Direct application of Navier-Stokes equations within armour blocks, is used to provide a more reliable approach to simulate wave run-up over breakwaters. A well-tested Reynolds-averaged Navier-Stokes (RANS Volume of Fluid (VOF code (Flow-3D was adopted for CFD computations. The computed results were compared with experimental data to check the validity of the model. Numerical results showed that the direct three dimensional (3D simulation method can deliver accurate results for wave run-up over rubble mound breakwaters. The results showed that the placement pattern of antifer units had a great impact on values of wave run-up so that by changing the placement pattern from regular to double pyramid can reduce the wave run-up by approximately 30%. Analysis was done to investigate the influences of surface roughness, energy dissipation in the pores of the armour layer and reduced wave run-up due to inflow into the armour and stone layer.

A theoretical study using the multiphase numerical simulation technique for effective use of H2 as blast furnaces fuel

Directory of Open Access Journals (Sweden)

Jose Adilson de Castro

2017-07-01

Full Text Available We present a numerical simulation procedure for analyzing hydrogen, oxygen and carbon dioxide gases injections mixed with pulverized coals within the tuyeres of blast furnaces. Effective use of H2 rich gas is highly attractive into the steelmaking blast furnace, considering the possibility of increasing the productivity and decreasing the specific emissions of carbon dioxide becoming the process less intensive in carbon utilization. However, the mixed gas and coal injection is a complex technology since significant changes on the inner temperature and gas flow patterns are expected, beyond to their effects on the chemical reactions and heat exchanges. Focusing on the evaluation of inner furnace status under such complex operation a comprehensive mathematical model has been developed using the multi interaction multiple phase theory. The BF, considered as a multiphase reactor, treats the lump solids (sinter, small coke, pellets, granular coke and iron ores, gas, liquids metal and slag and pulverized coal phases. The governing conservation equations are formulated for momentum, mass, chemical species and energy and simultaneously discretized using the numerical method of finite volumes. We verified the model with a reference operational condition using pulverized coal of 215 kg per ton of hot metal (kg thm−1. Thus, combined injections of varying concentrations of gaseous fuels with H2, O2 and CO2 are simulated with 220 kg thm−1 and 250 kg thm−1 coals injection. Theoretical analysis showed that stable operations conditions could be achieved with productivity increase of 60%. Finally, we demonstrated that the net carbon utilization per ton of hot metal decreased 12%.

High-speed photography of dynamic photoelastic experiment with a highly accurate blasting machine

Science.gov (United States)

Katsuyama, Kunihisa; Ogata, Yuji; Wada, Yuji; Hashizume, K.

1995-05-01

A high accurate blasting machine which could control 1 microsecond(s) was developed. At first, explosion of a bridge wire in an electric detonator was observed and next the detonations of caps were observed with a high speed camera. It is well known that a compressed stress wave reflects at the free face, it propagates to the backward as a tensile stress wave, and cracks grow when the tensile stress becomes the dynamic tensile strength. The behavior of these cracks has been discussed through the observation of the dynamic photoelastic high speed photography and the three dimensional dynamic stress analysis.

Nonlinear excitation of electron cyclotron waves by a monochromatic strong microwave: computer simulation analysis of the MINIX results

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, H.; Kimura, T.

1986-01-01

Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for this study was the one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the backscattered electromagnetic wave and electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear microphysics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 2 references, 4 figures.

Nonlinear excitation of electron cyclotron waves by a monochromatic strong microwave: computer simulation analysis of the MINIX results

International Nuclear Information System (INIS)

Matsumoto, H.; Kimura, T.

1986-01-01

Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for this study was the one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the backscattered electromagnetic wave and electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear microphysics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 2 references, 4 figures

Whistler Observations on DEMETER Compared with Full Electromagnetic Wave Simulations

Science.gov (United States)

Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Said, R.; Parrot, M.

2014-12-01

Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which strongly impacts the Van Allen radiation belt electron dynamics, is injected across the ionosphere into the Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Numerical models of trans-ionospheric propagation of such waves remain unvalidated, and early models may have overestimated the absorption, hindering a comprehensive understanding of the global impact of VLF waves in the loss of radiation belt electrons. In an attempt to remedy the problem of a lack of accurate trans-ionospheric propagation models, we have used a full electromagnetic wave method (FWM) numerical code to simulate the propagation of lightning-generated whistlers into the magnetosphere and compared the results with whistlers observed on the DEMETER satellite and paired with lightning stroke data from the National Lightning Detection Network (NLDN). We have identified over 20,000 whistlers occuring in 14 different passes of DEMETER over the central United States during the summer of 2009, and 14,000 of those occured within the 2000 km x 2000 km simulation grid we used. As shown in the attached figure, which shows a histogram of the ratio of the simulated whistler energy to the measured whistler energy for the 14,000 whistlers we compared, the simulation tends to slightly underestimate the total whistler energy injected by about 5 dB. However, the simulation underestimates the DEMETER measurements more as one gets further from the source lightning stroke, so since the signal to noise ratio of more distant whistlers will be smaller, possibly additive noise in the DEMETER measurements (which of course is not accounted for in the model) may explain some of the observed discrepancy.

Additive Manufacturing of Cranial Simulants for Blast Induced Traumatic Brain Injury

Science.gov (United States)

2017-08-28

REPORT TYPE 08/28/2017 Poster 4. TITLE AND SUBTITLE Additive Manufacturing of Cranial Sin1ulants for Blast Induced Traumatic Brain Injut’y 6... manufacturing techniques: Fused deposition modeling: ca sling molds Casting: white and gray matter Polymerization of injected solution...Sandia National Laboratories Conclusion MICHIGAN STAT[ l- I’ll I \\ I R <, I r \\ Additive manufacturrng provrdes a cost effective fabrration

Estimation of numerical uncertainty in computational fluid dynamics simulations of a passively controlled wave energy converter

DEFF Research Database (Denmark)

Wang, Weizhi; Wu, Minghao; Palm, Johannes

2018-01-01

for almost linear incident waves. First, we show that the computational fluid dynamics simulations have acceptable agreement to experimental data. We then present a verification and validation study focusing on the solution verification covering spatial and temporal discretization, iterative and domain......The wave loads and the resulting motions of floating wave energy converters are traditionally computed using linear radiation–diffraction methods. Yet for certain cases such as survival conditions, phase control and wave energy converters operating in the resonance region, more complete...... dynamics simulations have largely been overlooked in the wave energy sector. In this article, we apply formal verification and validation techniques to computational fluid dynamics simulations of a passively controlled point absorber. The phase control causes the motion response to be highly nonlinear even...

Design and Control of Full Scale Wave Energy Simulator System

DEFF Research Database (Denmark)

Pedersen, Henrik C.; Hansen, Anders Hedegaard; Hansen, Rico Hjerm

2012-01-01

For wave energy to become feasible it is a requirement that the efficiency and reliability of the power take-off (PTO) systems are significantly improved. The cost of installing and testing PTO-systems at sea are however very high, and the focus of the current paper is therefore on the design...... of a full scale wave simulator for testing PTO-systems for point absorbers. The main challenge is here to design a system, which mimics the behavior of a wave when interacting with a given PTO-system. The paper includes a description of the developed system, located at Aalborg University......, and the considerations behind the design. Based on the description a model of the system is presented, which, along with a description of the wave theory applied, makes the foundation for the control strategy. The objective of the control strategy is to emulate not only the wave behavior, but also the dynamic wave...

Simulations of nonlinear continuous wave pressure fields in FOCUS

Science.gov (United States)

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

2017-03-01

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

Simulation studies of plasma waves in the electron foreshock - The generation of Langmuir waves by a gentle bump-on-tail electron distribution

Science.gov (United States)

Dum, C. T.

1990-01-01

Particle simulation experiments were used to study the basic physical ingredients needed for building a global model of foreshock wave phenomena. In particular, the generation of Langmuir waves by a gentle bump-on-tail electron distribution is analyzed. It is shown that, with appropriately designed simulations experiments, quasi-linear theory can be quantitatively verified for parameters corresponding to the electron foreshock.

FastBLAST: homology relationships for millions of proteins.

Directory of Open Access Journals (Sweden)

Morgan N Price

Full Text Available BACKGROUND: All-versus-all BLAST, which searches for homologous pairs of sequences in a database of proteins, is used to identify potential orthologs, to find new protein families, and to provide rapid access to these homology relationships. As DNA sequencing accelerates and data sets grow, all-versus-all BLAST has become computationally demanding. METHODOLOGY/PRINCIPAL FINDINGS: We present FastBLAST, a heuristic replacement for all-versus-all BLAST that relies on alignments of proteins to known families, obtained from tools such as PSI-BLAST and HMMer. FastBLAST avoids most of the work of all-versus-all BLAST by taking advantage of these alignments and by clustering similar sequences. FastBLAST runs in two stages: the first stage identifies additional families and aligns them, and the second stage quickly identifies the homologs of a query sequence, based on the alignments of the families, before generating pairwise alignments. On 6.53 million proteins from the non-redundant Genbank database ("NR", FastBLAST identifies new families 25 times faster than all-versus-all BLAST. Once the first stage is completed, FastBLAST identifies homologs for the average query in less than 5 seconds (8.6 times faster than BLAST and gives nearly identical results. For hits above 70 bits, FastBLAST identifies 98% of the top 3,250 hits per query. CONCLUSIONS/SIGNIFICANCE: FastBLAST enables research groups that do not have supercomputers to analyze large protein sequence data sets. FastBLAST is open source software and is available at http://microbesonline.org/fastblast.

Numerical simulation of ultrasonic wave propagation in elastically anisotropic media

International Nuclear Information System (INIS)

Jacob, Victoria Cristina Cheade; Jospin, Reinaldo Jacques; Bittencourt, Marcelo de Siqueira Queiroz

2013-01-01

The ultrasonic non-destructive testing of components may encounter considerable difficulties to interpret some inspections results mainly in anisotropic crystalline structures. A numerical method for the simulation of elastic wave propagation in homogeneous elastically anisotropic media, based on the general finite element approach, is used to help this interpretation. The successful modeling of elastic field associated with NDE is based on the generation of a realistic pulsed ultrasonic wave, which is launched from a piezoelectric transducer into the material under inspection. The values of elastic constants are great interest information that provide the application of equations analytical models, until small and medium complexity problems through programs of numerical analysis as finite elements and/or boundary elements. The aim of this work is the comparison between the results of numerical solution of an ultrasonic wave, which is obtained from transient excitation pulse that can be specified by either force or displacement variation across the aperture of the transducer, and the results obtained from a experiment that was realized in an aluminum block in the IEN Ultrasonic Laboratory. The wave propagation can be simulated using all the characteristics of the material used in the experiment valuation associated to boundary conditions and from these results, the comparison can be made. (author)

Fully resolved simulations of expansion waves propagating into particle beds

Science.gov (United States)

Marjanovic, Goran; Hackl, Jason; Annamalai, Subramanian; Jackson, Thomas; Balachandar, S.

2017-11-01

There is a tremendous amount of research that has been done on compression waves and shock waves moving over particles but very little concerning expansion waves. Using 3-D direct numerical simulations, this study will explore expansion waves propagating into fully resolved particle beds of varying volume fractions and geometric arrangements. The objectives of these simulations are as follows: 1) To fully resolve all (1-way coupled) forces on the particles in a time varying flow and 2) to verify state-of-the-art drag models for such complex flows. We will explore a range of volume fractions, from very low ones that are similar to single particle flows, to higher ones where nozzling effects are observed between neighboring particles. Further, we will explore two geometric arrangements: body centered cubic and face centered cubic. We will quantify the effects that volume fraction and geometric arrangement plays on the drag forces and flow fields experienced by the particles. These results will then be compared to theoretical predictions from a model based on the generalized Faxen's theorem. This work was supported in part by the U.S. Department of Energy under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

30 CFR 780.13 - Operation plan: Blasting.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Operation plan: Blasting. 780.13 Section 780.13... SURFACE MINING PERMIT APPLICATIONS-MINIMUM REQUIREMENTS FOR RECLAMATION AND OPERATION PLAN § 780.13 Operation plan: Blasting. (a) Blasting plan. Each application shall contain a blasting plan for the proposed...

Control blasting of reinforced concrete

International Nuclear Information System (INIS)

Nagase, Tetsuo

1981-01-01

With the need of decommissioning nuclear power plants, it is urgently required to establish its methods and standards. In Shimizu Construction Co., Ltd., experimental feasibility studies have been made on explosive demolition method i.e. the controlled blasting for the massive concrete structures peculiar to nuclear power plants, considering low radiation exposure, safety and high efficiency. As such, four techniques of line drilling, cushion blasting, pre-splitting and guide hole blasting, respectively, are described with photographs. Assuming the selective demolition of activated concrete structures, the series of experiments showed the good results of clear-cut surfaces and the effect of blasting was confined properly. Moreover, the scattering of debris in blasting was able to be entirely prevented by the use of rubber belts. The generation of gas and dust was also little due to the small amount of the charge used. (J.P.N.)

Water-Depth-Based Prediction Formula for the Blasting Vibration Velocity of Lighthouse Caused by Underwater Drilling Blasting

Directory of Open Access Journals (Sweden)

Wenbin Gu

2017-01-01

Full Text Available Lighthouses are the most important hydraulic structures that should be protected during underwater drilling blasting. Thus, the effect of blasting vibration on lighthouse should be studied. On the basis of the dimensional analysis, we deduced a revised formula for water depth based on Sodev’s empirical formula and established the linear fitting model. During the underwater reef project in the main channel of Shipu Harbor in the Ningbo–Zhoushan Port, the blasting vibration data of the lighthouse near the underwater blasting area were monitored. The undetermined coefficient, resolvable coefficient, and F value of the two formulas were then obtained. The comparison of the data obtained from the two formulas showed that they can effectively predict the blasting vibration on the lighthouse. The correction formula that considers water depth can obviously reduce prediction errors and accurately predict blasting vibration.

30th International Symposium on Shock Waves

CERN Document Server

Sadot, Oren; Igra, Ozer

2017-01-01

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

Harmonic effects on ion-bulk waves and simulation of stimulated ion-bulk-wave scattering in CH plasmas

Science.gov (United States)

Feng, Q. S.; Zheng, C. Y.; Liu, Z. J.; Cao, L. H.; Xiao, C. Z.; Wang, Q.; Zhang, H. C.; He, X. T.

2017-08-01

Ion-bulk (IBk) wave, a novel branch with a phase velocity close to the ion’s thermal velocity, discovered by Valentini et al (2011 Plasma Phys. Control. Fusion 53 105017), is recently considered as an important electrostatic activity in solar wind, and thus of great interest to space physics and also inertial confinement fusion. The harmonic effects on IBk waves has been researched by Vlasov simulation for the first time. The condition of excitation of the large-amplitude IBk waves is given. The nature of nonlinear IBk waves in the condition of kFeng scattering (SFS) has been proposed and also verified by Vlasov-Maxwell code. In CH plasmas, in addition to the stimulated Brillouin scattering from multi ion-acoustic waves, there exists SIBS simultaneously. This research gives an insight into the SIBS in the field of laser plasma interaction.

The numerical simulation of Lamb wave propagation in laser welding of stainless steel

Science.gov (United States)

Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

2017-12-01

In order to explore the Lamb wave propagation in laser welding of stainless steel, the numerical simulation is used to show the feature of Lamb wave. In this paper, according to Lamb dispersion equation, excites the Lamb wave on the edge of thin stainless steel plate, and presents the reflection coefficient for quantizing the Lamb wave energy, the results show that the reflection coefficient is increased with the welding width increasing,

Simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

OpenAIRE

M. Füllekrug; C. Hanuise; M. Parrot

2010-01-01

Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz ...

BLEVE blast by expansion-controlled evaporation

NARCIS (Netherlands)

Berg, A.C. van den; Voort, M.M. van der; Weerheijm, J.; Versloot, N.H.A.

2006-01-01

This report presents a new method to calculate the blast effects originating from an exploding vessel of liquefied gas. Adequate blast calculation requires full knowledge of the blast source characteristics, that is, the release and subsequent evaporation rate of the flashing liquid. Because the

Influence of steel fibers on the shear and flexural performance of high-strength concrete beams tested under blast loads

Science.gov (United States)

Algassem, O.; Li, Y.; Aoude, H.

2017-09-01

This paper presents the results of a study examining the effect of steel fibres on the blast behaviour of high-strength concrete beams. As part of the study, a series of three large-scale beams built with high-strength concrete and steel fibres are tested under simulated blast loading using the shock-tube testing facility at the University of Ottawa. The specimens include two beams built with conventional high-strength concrete (HSC) and one beam built with high-strength concrete and steel fibres (HSFRC). The effect of steel fibres on the blast behaviour is examined by comparing the failure mode, mid-span displacements and, overall blast resistance of the specimens. The results show that the addition of steel fibres in high-strength concrete beams can prevent shear failure and substitute for shear reinforcement if added in sufficient quantity. Moreover, the use of steel fibres improves flexural response under blast loading by reducing displacements and increasing blast capacity. Finally, the provision of steel fibres is found to improve the fragmentation resistance of high-strength concrete under blast loads.

Novel types of surface acoustic wave microreflectors - Performance analysis and simulations

Science.gov (United States)

Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

1990-06-01

Surface acoustic waves for micrograting reflectors have been characterized. Based on the perturbation theory, eight different types of structures on an acoustic waveguide were analyzed. Results of simulations of all eight types of corrugation structures were evaluated in order to find the least leaky waveguide, the most efficient reflector (with minimum necessary perturbations), and the optimal mode shape for improved performances. General design curves are presented in order to illustrate the behavior of the incident and reflected waves under a variety of structural conditions. Analytic expressions for the calculations of the mode amplitude and mode shape, and for general acoustic corrugations are derived and then the simulations results are presented.

Simulation of mode converted ion Bernstein wave - beam deuteron interactions on TFTR

Science.gov (United States)

Herrmann, Mark; Fisch, Nathaniel

1998-11-01

Experiments on TFTR have documented strong interactions between mode converted ion Bernstein waves (MCIBW) and beam deuterons(D. S. Darrow et al.), Nucl. Fusion 36, 509 (1996).^,(N. J. Fisch et al.), IAEA, Vol. 1, p. 271 (1996). This is of particular interest in the study of α channelling, since the most promising scenarios(M. C. Herrmann and N. J. Fisch, Phys. Rev. Lett. 79), 1495 (1997). rely on a suitable combination of MCIBW and Alfvén eigenmodes to achieve the cooling of the α particles. Collisional effects, realistic wave fields, and a detailed model of the wave-particle interaction have been added to the Monte Carlo simulations which are used to simulate α channelling in order to model TFTR experiments(M. C. Herrmann, Ph.D. thesis, Princeton University, 1998.). The results are found to be in qualitative agreement with the data. In addition, the simulation is used, in conjunction with the data, to demonstrate the existence of the k_\\|-flip of the MCIBW, and to infer a diffusion coefficient for the beam deuterons interacting with the wave. This diffusion coefficient significantly exceeds what would be expected on the basis of quasilinear theory with the fields specified by 1 D ray tracing of the MCIBW.

Micromagnetic computer simulations of spin waves in nanometre-scale patterned magnetic elements

International Nuclear Information System (INIS)

Kim, Sang-Koog

2010-01-01

Current needs for further advances in the nanotechnologies of information-storage and -processing devices have attracted a great deal of interest in spin (magnetization) dynamics in nanometre-scale patterned magnetic elements. For instance, the unique dynamic characteristics of non-uniform magnetic microstructures such as various types of domain walls, magnetic vortices and antivortices, as well as spin wave dynamics in laterally restricted thin-film geometries, have been at the centre of extensive and intensive researches. Understanding the fundamentals of their unique spin structure as well as their robust and novel dynamic properties allows us to implement new functionalities into existing or future devices. Although experimental tools and theoretical approaches are effective means of understanding the fundamentals of spin dynamics and of gaining new insights into them, the limitations of those same tools and approaches have left gaps of unresolved questions in the pertinent physics. As an alternative, however, micromagnetic modelling and numerical simulation has recently emerged as a powerful tool for the study of a variety of phenomena related to spin dynamics of nanometre-scale magnetic elements. In this review paper, I summarize the recent results of simulations of the excitation and propagation and other novel wave characteristics of spin waves, highlighting how the micromagnetic computer simulation approach contributes to an understanding of spin dynamics of nanomagnetism and considering some of the merits of numerical simulation studies. Many examples of micromagnetic modelling for numerical calculations, employing various dimensions and shapes of patterned magnetic elements, are given. The current limitations of continuum micromagnetic modelling and of simulations based on the Landau-Lifshitz-Gilbert equation of motion of magnetization are also discussed, along with further research directions for spin-wave studies.

Micromagnetic computer simulations of spin waves in nanometre-scale patterned magnetic elements

Science.gov (United States)

Kim, Sang-Koog

2010-07-01

Current needs for further advances in the nanotechnologies of information-storage and -processing devices have attracted a great deal of interest in spin (magnetization) dynamics in nanometre-scale patterned magnetic elements. For instance, the unique dynamic characteristics of non-uniform magnetic microstructures such as various types of domain walls, magnetic vortices and antivortices, as well as spin wave dynamics in laterally restricted thin-film geometries, have been at the centre of extensive and intensive researches. Understanding the fundamentals of their unique spin structure as well as their robust and novel dynamic properties allows us to implement new functionalities into existing or future devices. Although experimental tools and theoretical approaches are effective means of understanding the fundamentals of spin dynamics and of gaining new insights into them, the limitations of those same tools and approaches have left gaps of unresolved questions in the pertinent physics. As an alternative, however, micromagnetic modelling and numerical simulation has recently emerged as a powerful tool for the study of a variety of phenomena related to spin dynamics of nanometre-scale magnetic elements. In this review paper, I summarize the recent results of simulations of the excitation and propagation and other novel wave characteristics of spin waves, highlighting how the micromagnetic computer simulation approach contributes to an understanding of spin dynamics of nanomagnetism and considering some of the merits of numerical simulation studies. Many examples of micromagnetic modelling for numerical calculations, employing various dimensions and shapes of patterned magnetic elements, are given. The current limitations of continuum micromagnetic modelling and of simulations based on the Landau-Lifshitz-Gilbert equation of motion of magnetization are also discussed, along with further research directions for spin-wave studies.

Simulations of Shock Wave Interaction with a Particle Cloud

Science.gov (United States)

Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S.'Bala'

2016-11-01

Simulations of a shock wave interacting with a cloud of particles are performed in an attempt to understand similar phenomena observed in dispersal of solid particles under such extreme environment as an explosion. We conduct numerical experiments in which a particle curtain fills only 87% of the shock tube from bottom to top. As such, the particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In this study, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. In these simulations we use a Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. Measurements of particle dispersion are made at different initial volume fractions of the particle cloud. A detailed analysis of the evolution of the particle curtain with respect to the initial conditions is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

International Nuclear Information System (INIS)

Bae, Jaehan; Hartmann, Lee; Nelson, Richard P.; Richard, Samuel

2016-01-01

We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10 −4 in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10 −5 . This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

Physical simulation technique on the behaviour of oil spills in grease ice under wave actions

International Nuclear Information System (INIS)

Li, Z.; Hollebone, B.; Fingas, M.; Fieldhouse, B.

2008-01-01

Light or medium oil spilled on ice tends to rise and remain the surface in unconsolidated frazil or grease ice. This study looked for a new system for studying the oil emulsion in grease ice under experimental conditions. A physical simulation technique was designed to test the effect of wave energy on the spilled oil grease ice emulsion. The newly developed test system has the ability to perform simulation tests in wave, wave-ice, wave-oil and wave-ice-oil. This paper presented the design concept of the developed test system and introduced the experimental certifications of its capability in terms of temperature control, wave-making and grease ice-making. The key feature of the technique is a mini wave flume which derives its wave making power from an oscillator in a chemical laboratory. Video cameras record the wave action in the flume in order to obtain wave parameters. The wave making capability tests in this study were used to determine the relation of wave height, length and frequency with oscillator power transfer, oscillator frequency and the depth of the water flume. 16 refs., 10 figs

30 CFR 75.1323 - Blasting circuits.

Science.gov (United States)

2010-07-01

...) Blasting circuits shall be protected from sources of stray electric current. (b) Detonators made by different manufacturers shall not be combined in the same blasting circuit. (c) Detonator leg wires shall be... used between the blasting cable and detonator circuitry shall— (1) Be undamaged; (2) Be well insulated...

SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST

Directory of Open Access Journals (Sweden)

Sugih Sudharma Tjandra

2015-11-01

Full Text Available Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.

Nonlinear plasma wave models in 3D fluid simulations of laser-plasma interaction

Science.gov (United States)

Chapman, Thomas; Berger, Richard; Arrighi, Bill; Langer, Steve; Banks, Jeffrey; Brunner, Stephan

2017-10-01

Simulations of laser-plasma interaction (LPI) in inertial confinement fusion (ICF) conditions require multi-mm spatial scales due to the typical laser beam size and durations of order 100 ps in order for numerical laser reflectivities to converge. To be computationally achievable, these scales necessitate a fluid-like treatment of light and plasma waves with a spatial grid size on the order of the light wave length. Plasma waves experience many nonlinear phenomena not naturally described by a fluid treatment, such as frequency shifts induced by trapping, a nonlinear (typically suppressed) Landau damping, and mode couplings leading to instabilities that can cause the plasma wave to decay rapidly. These processes affect the onset and saturation of stimulated Raman and Brillouin scattering, and are of direct interest to the modeling and prediction of deleterious LPI in ICF. It is not currently computationally feasible to simulate these Debye length-scale phenomena in 3D across experimental scales. Analytically-derived and/or numerically benchmarked models of processes occurring at scales finer than the fluid simulation grid offer a path forward. We demonstrate the impact of a range of kinetic processes on plasma reflectivity via models included in the LPI simulation code pF3D. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Pulse-wave propagation in straight-geometry vessels for stiffness estimation: theory, simulations, phantoms and in vitro findings.

Science.gov (United States)

Shahmirzadi, Danial; Li, Ronny X; Konofagou, Elisa E

2012-11-01

Pulse wave imaging (PWI) is an ultrasound-based method for noninvasive characterization of arterial stiffness based on pulse wave propagation. Reliable numerical models of pulse wave propagation in normal and pathological aortas could serve as powerful tools for local pulse wave analysis and a guideline for PWI measurements in vivo. The objectives of this paper are to (1) apply a fluid-structure interaction (FSI) simulation of a straight-geometry aorta to confirm the Moens-Korteweg relationship between the pulse wave velocity (PWV) and the wall modulus, and (2) validate the simulation findings against phantom and in vitro results. PWI depicted and tracked the pulse wave propagation along the abdominal wall of canine aorta in vitro in sequential Radio-Frequency (RF) ultrasound frames and estimates the PWV in the imaged wall. The same system was also used to image multiple polyacrylamide phantoms, mimicking the canine measurements as well as modeling softer and stiffer walls. Finally, the model parameters from the canine and phantom studies were used to perform 3D two-way coupled FSI simulations of pulse wave propagation and estimate the PWV. The simulation results were found to correlate well with the corresponding Moens-Korteweg equation. A high linear correlation was also established between PWV² and E measurements using the combined simulation and experimental findings (R² =  0.98) confirming the relationship established by the aforementioned equation.

Novel method to dynamically load cells in 3D-hydrogels culture for blast injury studies

Science.gov (United States)

Sory, David R.; Areias, Anabela C.; Overby, Darryl R.; Proud, William G.

2017-01-01

For at least a century explosive devices have been one of the most important causes of injuries in military conflicts as well as in terrorist attacks. Although significant experimental and modelling efforts have been focussed on blast injuries at the organ or tissue level, few studies have investigated the mechanisms of blast injuries at the cellular level. This paper introduces an in vitro method compatible with living cells to examine the effects of high stress and short-duration pulses relevant to blast loadings and blunt trauma. The experimental phase involves high strain-rate axial compression of cylindrical specimens within an hermetically sealed chamber made of biocompatible polymer. Numerical simulations were performed in order to verify the experimental loading conditions and to characterize the loading path within the sample. A proof of concept is presented so as to establish a new window to address fundamental questions regarding blast injury at the cellular level.

Discrete-State Simulated Annealing For Traveling-Wave Tube Slow-Wave Circuit Optimization

Science.gov (United States)

Wilson, Jeffrey D.; Bulson, Brian A.; Kory, Carol L.; Williams, W. Dan (Technical Monitor)

2001-01-01

Algorithms based on the global optimization technique of simulated annealing (SA) have proven useful in designing traveling-wave tube (TWT) slow-wave circuits for high RF power efficiency. The characteristic of SA that enables it to determine a globally optimized solution is its ability to accept non-improving moves in a controlled manner. In the initial stages of the optimization, the algorithm moves freely through configuration space, accepting most of the proposed designs. This freedom of movement allows non-intuitive designs to be explored rather than restricting the optimization to local improvement upon the initial configuration. As the optimization proceeds, the rate of acceptance of non-improving moves is gradually reduced until the algorithm converges to the optimized solution. The rate at which the freedom of movement is decreased is known as the annealing or cooling schedule of the SA algorithm. The main disadvantage of SA is that there is not a rigorous theoretical foundation for determining the parameters of the cooling schedule. The choice of these parameters is highly problem dependent and the designer needs to experiment in order to determine values that will provide a good optimization in a reasonable amount of computational time. This experimentation can absorb a large amount of time especially when the algorithm is being applied to a new type of design. In order to eliminate this disadvantage, a variation of SA known as discrete-state simulated annealing (DSSA), was recently developed. DSSA provides the theoretical foundation for a generic cooling schedule which is problem independent, Results of similar quality to SA can be obtained, but without the extra computational time required to tune the cooling parameters. Two algorithm variations based on DSSA were developed and programmed into a Microsoft Excel spreadsheet graphical user interface (GUI) to the two-dimensional nonlinear multisignal helix traveling-wave amplifier analysis program TWA3

MONTE CARLO SIMULATION MODEL OF ENERGETIC PROTON TRANSPORT THROUGH SELF-GENERATED ALFVEN WAVES

Energy Technology Data Exchange (ETDEWEB)

Afanasiev, A.; Vainio, R., E-mail: alexandr.afanasiev@helsinki.fi [Department of Physics, University of Helsinki (Finland)

2013-08-15

A new Monte Carlo simulation model for the transport of energetic protons through self-generated Alfven waves is presented. The key point of the model is that, unlike the previous ones, it employs the full form (i.e., includes the dependence on the pitch-angle cosine) of the resonance condition governing the scattering of particles off Alfven waves-the process that approximates the wave-particle interactions in the framework of quasilinear theory. This allows us to model the wave-particle interactions in weak turbulence more adequately, in particular, to implement anisotropic particle scattering instead of isotropic scattering, which the previous Monte Carlo models were based on. The developed model is applied to study the transport of flare-accelerated protons in an open magnetic flux tube. Simulation results for the transport of monoenergetic protons through the spectrum of Alfven waves reveal that the anisotropic scattering leads to spatially more distributed wave growth than isotropic scattering. This result can have important implications for diffusive shock acceleration, e.g., affect the scattering mean free path of the accelerated particles in and the size of the foreshock region.

Bioceramic inlays do not improve mechanical incorporation of grit-blasted titanium stems in the proximal sheep femur.

Science.gov (United States)

Keränen, Pauli; Koort, Jyri; Itälä, Ari; Ylänen, Heimo; Dalstra, Michel; Hupa, Mikko; Kommonen, Bertel; Aro, Hannu T

2010-03-15

The aim of the present study was to determine, if bioactive glass (BG) surface inlays improve osseointegration of titanium implants in the proximal femur of adult sheep. In simulation of uncemented primary stems (nine animals), only the proximal part of the implants was grit-blasted and three surface slots of the grit-blasted region were filled with sintered BG microspheres. Primary stems were implanted using press-fit technique. In revision stem simulation (eight animals), grit-blasting was extended over the whole implant and seven perforating holes of the stem were filled by sintered BG granules. Revision stems were implanted with a mixture of autogenous bone graft and BG granules. Comparison with solid partially or fully grit-blasted control stems implanted in the contralateral femurs was performed in the primary and revision stem experiments at 12 and 25 weeks, respectively. Implant incorporation was evaluated by torsional failure testing and histomorphometry. Only one-third of the primary stems anchored mechanically to bone. The revision stems incorporated better and the BG inlays of the revision stems showed ingrowth of new bone. However, there were no significant differences in the torsional failure loads between the stems with BG inlays and the control stems. In conclusion, surface BG inlays gave no measurable advantage in mechanical incorporation of grit-blasted titanium implants. Overall, the proximal sheep femur, characterized by minimal amount of cancellous bone and the presence of adipocytic bone marrow, seemed to present compromised bone healing conditions. (c) 2009 Wiley Periodicals, Inc.

Ultra Safe And Secure Blasting System

Energy Technology Data Exchange (ETDEWEB)

Hart, M M

2009-07-27

The Ultra is a blasting system that is designed for special applications where the risk and consequences of unauthorized demolition or blasting are so great that the use of an extraordinarily safe and secure blasting system is justified. Such a blasting system would be connected and logically welded together through digital code-linking as part of the blasting system set-up and initialization process. The Ultra's security is so robust that it will defeat the people who designed and built the components in any attempt at unauthorized detonation. Anyone attempting to gain unauthorized control of the system by substituting components or tapping into communications lines will be thwarted in their inability to provide encrypted authentication. Authentication occurs through the use of codes that are generated by the system during initialization code-linking and the codes remain unknown to anyone, including the authorized operator. Once code-linked, a closed system has been created. The system requires all components connected as they were during initialization as well as a unique code entered by the operator for function and blasting.

Numerical Simulations of Kinetic Alfvén Waves to Study Spectral ...

Indian Academy of Sciences (India)

Numerical Simulations of Kinetic Alfvén Waves to Study Spectral. Index in Solar Wind Turbulence and Particle Heating. R. P. Sharma. ∗. & H. D. Singh. Center for Energy Studies, Indian Institute of Technology, Delhi 110 016, India. ∗ e-mail: rpsharma@ces.iitd.ernet.in. Abstract. We present numerical simulations of the ...

WImpiBLAST: web interface for mpiBLAST to help biologists perform large-scale annotation using high performance computing.

Directory of Open Access Journals (Sweden)

Parichit Sharma

Full Text Available The function of a newly sequenced gene can be discovered by determining its sequence homology with known proteins. BLAST is the most extensively used sequence analysis program for sequence similarity search in large databases of sequences. With the advent of next generation sequencing technologies it has now become possible to study genes and their expression at a genome-wide scale through RNA-seq and metagenome sequencing experiments. Functional annotation of all the genes is done by sequence similarity search against multiple protein databases. This annotation task is computationally very intensive and can take days to obtain complete results. The program mpiBLAST, an open-source parallelization of BLAST that achieves superlinear speedup, can be used to accelerate large-scale annotation by using supercomputers and high performance computing (HPC clusters. Although many parallel bioinformatics applications using the Message Passing Interface (MPI are available in the public domain, researchers are reluctant to use them due to lack of expertise in the Linux command line and relevant programming experience. With these limitations, it becomes difficult for biologists to use mpiBLAST for accelerating annotation. No web interface is available in the open-source domain for mpiBLAST. We have developed WImpiBLAST, a user-friendly open-source web interface for parallel BLAST searches. It is implemented in Struts 1.3 using a Java backbone and runs atop the open-source Apache Tomcat Server. WImpiBLAST supports script creation and job submission features and also provides a robust job management interface for system administrators. It combines script creation and modification features with job monitoring and management through the Torque resource manager on a Linux-based HPC cluster. Use case information highlights the acceleration of annotation analysis achieved by using WImpiBLAST. Here, we describe the WImpiBLAST web interface features and architecture

WImpiBLAST: web interface for mpiBLAST to help biologists perform large-scale annotation using high performance computing.

Science.gov (United States)

Sharma, Parichit; Mantri, Shrikant S

2014-01-01

The function of a newly sequenced gene can be discovered by determining its sequence homology with known proteins. BLAST is the most extensively used sequence analysis program for sequence similarity search in large databases of sequences. With the advent of next generation sequencing technologies it has now become possible to study genes and their expression at a genome-wide scale through RNA-seq and metagenome sequencing experiments. Functional annotation of all the genes is done by sequence similarity search against multiple protein databases. This annotation task is computationally very intensive and can take days to obtain complete results. The program mpiBLAST, an open-source parallelization of BLAST that achieves superlinear speedup, can be used to accelerate large-scale annotation by using supercomputers and high performance computing (HPC) clusters. Although many parallel bioinformatics applications using the Message Passing Interface (MPI) are available in the public domain, researchers are reluctant to use them due to lack of expertise in the Linux command line and relevant programming experience. With these limitations, it becomes difficult for biologists to use mpiBLAST for accelerating annotation. No web interface is available in the open-source domain for mpiBLAST. We have developed WImpiBLAST, a user-friendly open-source web interface for parallel BLAST searches. It is implemented in Struts 1.3 using a Java backbone and runs atop the open-source Apache Tomcat Server. WImpiBLAST supports script creation and job submission features and also provides a robust job management interface for system administrators. It combines script creation and modification features with job monitoring and management through the Torque resource manager on a Linux-based HPC cluster. Use case information highlights the acceleration of annotation analysis achieved by using WImpiBLAST. Here, we describe the WImpiBLAST web interface features and architecture, explain design

3-D FDTD simulation of shear waves for evaluation of complex modulus imaging.

Science.gov (United States)

Orescanin, Marko; Wang, Yue; Insana, Michael

2011-02-01

The Navier equation describing shear wave propagation in 3-D viscoelastic media is solved numerically with a finite differences time domain (FDTD) method. Solutions are formed in terms of transverse scatterer velocity waves and then verified via comparison to measured wave fields in heterogeneous hydrogel phantoms. The numerical algorithm is used as a tool to study the effects on complex shear modulus estimation from wave propagation in heterogeneous viscoelastic media. We used an algebraic Helmholtz inversion (AHI) technique to solve for the complex shear modulus from simulated and experimental velocity data acquired in 2-D and 3-D. Although 3-D velocity estimates are required in general, there are object geometries for which 2-D inversions provide accurate estimations of the material properties. Through simulations and experiments, we explored artifacts generated in elastic and dynamic-viscous shear modulus images related to the shear wavelength and average viscosity.

SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

Energy Technology Data Exchange (ETDEWEB)

Bae, Jaehan; Hartmann, Lee [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Nelson, Richard P.; Richard, Samuel, E-mail: jaehbae@umich.edu, E-mail: lhartm@umich.edu, E-mail: r.p.nelson@qmul.ac.uk, E-mail: samuel.richard@qmul.ac.uk [Astronomy Unit, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

2016-09-20

We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10{sup −4} in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10{sup −5}. This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.