Science.gov

Sample records for 3-foot projectile impactor

  1. Virtual impactor

    DOEpatents

    Yeh, Hsu-Chi; Chen, Bean T.; Cheng, Yung-Sung; Newton, George J.

    1988-08-30

    A virtual impactor having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency.

  2. Virtual impactor

    DOEpatents

    Yeh, H.C.; Chen, B.T.; Cheng, Y.S.; Newton, G.J.

    1988-08-30

    A virtual impactor is described having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent to the inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency. 4 figs.

  3. Projectile stopping system

    DOEpatents

    Karr, T.J.; Pittenger, L.C.

    1996-11-26

    A projectile interceptor launches a projectile catcher into the path of a projectile. In one embodiment, signals indicative of the path of a projectile are received by the projectile interceptor. A flinger mechanism has a projectile catcher releasably attached thereto, such that the projectile catcher can be released and launched from the flinger mechanism. A controller connected to the flinger mechanism uses the signals indicative of the path of the projectile to determine the launch parameters of the projectile catcher. The controller directs the flinger mechanism to release the projectile catcher such that the projectile catcher is launched into the path of the projectile and intercepts the projectile. 13 figs.

  4. Projectile stopping system

    DOEpatents

    Karr, Thomas J.; Pittenger, Lee C.

    1996-01-01

    A projectile interceptor launches a projectile catcher into the path of a projectile. In one embodiment, signals indicative of the path of a projectile are received by the projectile interceptor. A flinger mechanism has a projectile catcher releasably attached thereto, such that the projectile catcher can be released and launched from the flinger mechanism. A controller connected to the flinger mechanism uses the signals indicative of the path of the projectile to determine the launch parameters of the projectile catcher. The controller directs the flinger mechanism to release the projectile catcher such that the projectile catcher is launched into the path of the projectile and intercepts the projectile.

  5. Asteroid Kinetic Impactor Missions

    NASA Astrophysics Data System (ADS)

    Chesley, Steven

    2015-08-01

    Asteroid impact missions can be carried out as a relatively low-cost add-ons to most asteroid rendezvous missions and such impact experiments have tremendous potential, both scientifically and in the arena of planetary defense.The science returns from an impactor demonstration begin with the documentation of the global effects of the impact, such as changes in orbit and rotation state, the creation and dissipation of an ejecta plume and debris disk, and morphological changes across the body due to the transmission of seismic waves, which might induce landslides and toppling of boulders, etc. At a local level, an inspection of the impact crater and ejecta blanket reveals critical material strength information, as well as spectral differences between the surface and subsurface material.From the planetary defense perspective, an impact demonstration will prove humankind’s capacity to alter the orbit of a potentially threatening asteroid. This technological leap comes in two parts. First, terminal guidance systems that can deliver an impactor with small errors relative to the ~100-200 meter size of a likely impactor have yet to be demonstrated in a deep space environment. Second, the response of an asteroid to such an impact is only understood theoretically due to the potentially significant dependence on the momentum carried by escaping ejecta, which would tend to enhance the deflection by tens of percent and perhaps as much as a factor of a few. A lack of validated understanding of momentum enhancement is a significant obstacle in properly sizing a real-world impactor deflection mission.This presentation will describe the drivers for asteroid impact demonstrations and cover the range of such concepts, starting with ESA’s pioneering Don Quijote mission concept and leading to a brief description of concepts under study at the present time, including the OSIRIS-REx/ISIS, BASiX/KIX and AIM/DART (AIDA) concepts.

  6. High efficiency virtual impactor

    DOEpatents

    Loo, B.W.

    1980-03-27

    Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor for separating an inlet flow (Q/sub 0/) having particulate contaminants into a coarse particle flow (Q/sub 1/) and a fine particle flow (Q/sub 2/) to enable collection of such particles on different filters for separate analysis. An inlet particle acceleration nozzle and coarse particle collection probe member having a virtual impaction opening are aligned along a single axis and spaced apart to define a flow separation region at which the fine particle flow (Q/sub 2/) is drawn radially outward into a chamber while the coarse particle flow (Q/sub 1/) enters the virtual impaction opening.

  7. Particle chemistry impactor experiment

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Snetsinger, K. G.; Ferry, G. V.; Goodman, J. K.; Verma, S.

    1990-01-01

    Polar stratospheric cloud (PSC) particles are collected on impactors and studied with regard to physical and chemical properties to help explain the importance of heterogeneous chemical reactions for stratospheric ozone depletion. The nitric, hydrochloric, and sulfuric acid content of stratospheric aerosol particles collected at 18 km altitude was determined. It is suggested that nitric acid is a component of polar stratospheric clouds. This is important for two reasons: (1) it proves that chlorine activation takes place at the surface of PSC particles by converting chemically inert chlorine nitrate to chlorine radicals that can react with ozone; and (2) if the PSC particles are large enough to settle out from the stratosphere, the possibility of nitric acid removal can result in the denitrification of the stratosphere.

  8. Survival of the impactor during hypervelocity collisions II: An analogue for high porosity targets.

    NASA Astrophysics Data System (ADS)

    Avdellidou, C.; Price, M. C.; Delbo, M.; Cole, M. J.

    2016-09-01

    We investigated how a target's porosity affects the outcome of a collision, with respect to the impactor's fate. Laboratory impact experiments using peridot projectiles were performed at a speed range between 0.3 and 3.0 km/s, onto high porosity water-ice (40%) and fine-grained calcium carbonate (70%) targets. We report that the amount of implanted material in the target body increases with increasing target's porosity, while the size frequency distribution of the projectile's ejecta fragments becomes steeper. A supplementary Raman study showed no sign of change of the Raman spectra of the recovered olivine projectile fragments indicate minimal physical change.

  9. High efficiency virtual impactor

    DOEpatents

    Loo, Billy W.

    1981-01-01

    Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor (11) for separating an inlet flow (Q.sub.O) having particulate contaminants into a coarse particle flow (Q.sub.1) and a fine particle flow (Q.sub.2) to enable collection of such particles on different filters (19a, 19b) for separate analysis. An inlet particle acceleration nozzle (28) and coarse particle collection probe member (37) having a virtual impaction opening (41) are aligned along a single axis (13) and spaced apart to define a flow separation region (14) at which the fine particle flow (Q.sub.2) is drawn radially outward into a chamber (21) while the coarse particle flow (Q.sub.1) enters the virtual impaction opening (41). Symmetrical outlet means (47) for the chamber (21) provide flow symmetry at the separation region (14) to assure precise separation of particles about a cutpoint size and to minimize losses by wall impaction and gravitational settling. Impulse defocusing means (42) in the probe member (37) provides uniform coarse particle deposition on the filter (19a) to aid analysis. Particle losses of less than 1% for particles in the 0 to 20 micron range may be realized.

  10. Penetration of Granular Projectiles into a Water Target

    PubMed Central

    González-Gutiérrez, Jorge; Carrillo-Estrada, J. L.; Ruiz-Suárez, J. C.

    2014-01-01

    The penetration of low-speed projectiles into a water target has been studied in the last several years to understand the physics behind the formation and collapse of cavities. In such studies, the projectiles employed were solid bodies or liquid drops. Here we report similar impact experiments using granular projectiles, with the aim to investigate how the morphology of the cavities is determined by the balance between the dynamic pressure exerted by the fluid and the cohesive strength of the impactors. From the results we present and discuss in this manuscript, we speculate on the dynamics of meteorite disintegration in the atmosphere of our planet. PMID:25342448

  11. Penetration of granular projectiles into a water target.

    PubMed

    González-Gutiérrez, Jorge; Carrillo-Estrada, J L; Ruiz-Suárez, J C

    2014-01-01

    The penetration of low-speed projectiles into a water target has been studied in the last several years to understand the physics behind the formation and collapse of cavities. In such studies, the projectiles employed were solid bodies or liquid drops. Here we report similar impact experiments using granular projectiles, with the aim to investigate how the morphology of the cavities is determined by the balance between the dynamic pressure exerted by the fluid and the cohesive strength of the impactors. From the results we present and discuss in this manuscript, we speculate on the dynamics of meteorite disintegration in the atmosphere of our planet. PMID:25342448

  12. Superconducting Magnetic Projectile Launcher

    NASA Technical Reports Server (NTRS)

    Jan, Darrell L.; Lawson, Daniel D.

    1991-01-01

    Proposed projectile launcher exploits Meissner effect to transfer much of kinetic energy of relatively massive superconducting plunger to smaller projectile, accelerating projectile to high speed. Because it operates with magnetic fields, launcher not limited by gas-expansion thermodynamics. Plunger energized mechanically and/or chemically, avoiding need for large electrical power supplies and energy-storage systems. Potential applications include launching of projectiles for military purposes and for scientific and industrial tests of hypervelocity impacts.

  13. 20. LOCK GATES, 3 FOOT WALKWAY, ADJUSTMENT AT GUDGEON PIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. LOCK GATES, 3 FOOT WALKWAY, ADJUSTMENT AT GUDGEON PIN AND QUOIN SHOE. May 1933 - Mississippi River 9-Foot Channel Project, Lock & Dam No. 17, Upper Mississippi River, New Boston, Mercer County, IL

  14. An ordinary chondrite impactor for the Popigai crater, Siberia

    NASA Astrophysics Data System (ADS)

    Tagle, Roald; Claeys, Philippe

    2005-06-01

    With a diameter of ˜100 km, Popigai in Northern Siberia is the largest crater known in the Cenozoic. The concentrations in platinum group elements (PGE) were analyzed in twenty samples of homogeneous impact melt collected in the northwestern flank of the crater to identify the composition of the projectile. The method selected was preconcentration by NiS fire assay followed by inductively coupled plasma-mass spectrometry (ICP-MS). This technique measures all the PGE (except Os) and by using aliquots >10g, the results are highly reproducible. The major and trace element composition of the impact melt resembles that of gneissic lithologies of the Anabar shield, which are representative of the target rock. The PGE are enriched in the melt by factors of 3 to 14 compared to the main target lithology, but the meteoritic contamination is only around 0.2 wt.%. Using plots of elemental ratios such as Ru/Rh vs. Pt/Pd or Ru/Rh vs. Pd/Ir, the Popigai impactor is clearly identified as an ordinary chondrite and most likely L-chondrite. This study indicates that PGE elemental ratios allow discrimination of the type of impactor, even in the case of low meteoritic contamination. This study confirms that a significant fraction of the crater-forming projectiles presently documented could have an ordinary chondrite composition. Their probable source, the S-type asteroids, appears to form the majority of the bodies in the main asteroid belt and among Near Earth Objects (NEOs). The ordinary chondrite origin of the Popigai projectile supports an asteroidal origin for the late Eocene impacts as a plausible alternative to the comet shower scenario proposed by Farley et al. (1998).

  15. Shock melting of the Canyon Diablo impactor: constraints from nickel-59 contents and numerical modeling.

    NASA Astrophysics Data System (ADS)

    Schnabel, C.; Pierazzo, E.; Xue, S.; Herzog, G. F.; Masarik, J.; Cresswell, R. G.; di Tada, M. L.; Liu, K.; Fifield, L. K.

    1999-07-01

    Two main types of material survive from the Canyon Diablo impactor, which produced Meteor Crater in Arizona: iron meteorites, which did not melt during the impact; and spheroids, which did. Ultrasensitive measurements using accelerator mass spectrometry show that the meteorites contain about seven times as much nickel-59 as the spheroids. Lower average nickel-59 contents in the spheroids indicate that they typically came from 0.5 to 1 m deeper in the impactor than did the meteorites. Numerical modeling for an impact velocity of 20 km sec-1 shows that a shell 1.5 to 2 m thick, corresponding to 16% of the projectile volume, remained solid on the rear surface; that most of the projectile melted; and that little, if any, vaporized.

  16. Leftovers from Ancient Lunar Impactors

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.; Taylor, G. J.

    2012-06-01

    The lunar basins mark a time, over three and a half billion years ago, of extreme bombardment in the early Solar System, including in the young Earth-Moon system. What hit the Moon (and by proxy, Earth) at the end of the basin-forming epoch has now been determined directly, for the first time, from the analyses of impactor debris found in samples returned from the Apollo 16 landing site. Katie Joy (Lunar and Planetary Institute, NASA Lunar Science Institute) and colleagues working in Houston and Honolulu identified 30 tiny mineral and rock relics of chondritic impactors during their systematic search of regolith breccias bormed between about 3.8-3.4 billion years ago. The relatively uniform composition of these chondritic meteorite fragments is in contrast to the variety of meteorites in our collections, supporting the idea that the influx of materials bombarding the Moon and Earth 3.4 billion years ago, or more, was different from more recent times.

  17. Survivability of copper projectiles during hypervelocity impacts in porous ice: A laboratory investigation of the survivability of projectiles impacting comets or other bodies

    NASA Astrophysics Data System (ADS)

    McDermott, K. H.; Price, M. C.; Cole, M.; Burchell, M. J.

    2016-04-01

    During hypervelocity impact (>a few km s-1) the resulting cratering and/or disruption of the target body often outweighs interest on the outcome of the projectile material, with the majority of projectiles assumed to be vaporised. However, on Earth, fragments, often metallic, have been recovered from impact sites, meaning that metallic projectile fragments may survive a hypervelocity impact and still exist within the wall, floor and/or ejecta of the impact crater post-impact. The discovery of the remnant impactor composition within the craters of asteroids, planets and comets could provide further information regarding the impact history of a body. Accordingly, we study in the laboratory the survivability of 1 and 2 mm diameter copper projectiles fired onto ice at speeds between 1.00 and 7.05 km s-1. The projectile was recovered intact at speeds up to 1.50 km s-1, with no ductile deformation, but some surface pitting was observed. At 2.39 km s-1, the projectile showed increasing ductile deformation and broke into two parts. Above velocities of 2.60 km s-1 increasing numbers of projectile fragments were identified post impact, with the mean size of the fragments decreasing with increasing impact velocity. The decrease in size also corresponds with an increase in the number of projectile fragments recovered, as with increasing shock pressure the projectile material is more intensely disrupted, producing smaller and more numerous fragments. The damage to the projectile is divided into four classes with increasing speed and shock pressure: (1) minimal damage, (2) ductile deformation, start of break up, (3) increasing fragmentation, and (4) complete fragmentation. The implications of such behaviour is considered for specific examples of impacts of metallic impactors onto Solar System bodies, including LCROSS impacting the Moon, iron meteorites onto Mars and NASA's "Deep Impact" mission where a spacecraft impacted a comet.

  18. Hybrid armature projectile

    DOEpatents

    Hawke, R.S.; Asay, J.R.; Hall, C.A.; Konrad, C.H.; Sauve, G.L.; Shahinpoor, M.; Susoeff, A.R.

    1993-03-02

    A projectile for a railgun that uses a hybrid armature and provides a seed block around part of the outer surface of the projectile to seed the hybrid plasma brush. In addition, the hybrid armature is continuously vaporized to replenish plasma in a plasma armature to provide a tandem armature and provides a unique ridge and groove to reduce plasma blowby.

  19. Hybrid armature projectile

    DOEpatents

    Hawke, Ronald S.; Asay, James R.; Hall, Clint A.; Konrad, Carl H.; Sauve, Gerald L.; Shahinpoor, Mohsen; Susoeff, Allan R.

    1993-01-01

    A projectile for a railgun that uses a hybrid armature and provides a seed block around part of the outer surface of the projectile to seed the hybrid plasma brush. In addition, the hybrid armature is continuously vaporized to replenish plasma in a plasma armature to provide a tandem armature and provides a unique ridge and groove to reduce plasama blowby.

  20. Projectile Motion Revisited.

    ERIC Educational Resources Information Center

    Lucie, Pierre

    1979-01-01

    Analyzes projectile motion using symmetry and simple geometry. Deduces the direction of velocity at any point, range, time of flight, maximum height, safety parabola, and maximum range for a projectile launched upon a plane inclined at any angle with respect to the horizontal. (Author/GA)

  1. Projectile Motion with Mathematica.

    ERIC Educational Resources Information Center

    de Alwis, Tilak

    2000-01-01

    Describes how to use the computer algebra system (CAS) Mathematica to analyze projectile motion with and without air resistance. These experiments result in several conjectures leading to theorems. (Contains 17 references.) (Author/ASK)

  2. A Projectile Motion Bullseye.

    ERIC Educational Resources Information Center

    Lamb, William G.

    1985-01-01

    Explains a projectile motion experiment involving a bow and arrow. Procedures to measure "muzzle" velocity, bow elastic potential energy, range, flight time, wind resistance, and masses are considered. (DH)

  3. Small caliber guided projectile

    DOEpatents

    Jones, James F.; Kast, Brian A.; Kniskern, Marc W.; Rose, Scott E.; Rohrer, Brandon R.; Woods, James W.; Greene, Ronald W.

    2010-08-24

    A non-spinning projectile that is self-guided to a laser designated target and is configured to be fired from a small caliber smooth bore gun barrel has an optical sensor mounted in the nose of the projectile, a counterbalancing mass portion near the fore end of the projectile and a hollow tapered body mounted aft of the counterbalancing mass. Stabilizing strakes are mounted to and extend outward from the tapered body with control fins located at the aft end of the strakes. Guidance and control electronics and electromagnetic actuators for operating the control fins are located within the tapered body section. Output from the optical sensor is processed by the guidance and control electronics to produce command signals for the electromagnetic actuators. A guidance control algorithm incorporating non-proportional, "bang-bang" control is used to steer the projectile to the target.

  4. Projectile Motion Demonstration

    NASA Astrophysics Data System (ADS)

    Graf, Erlend H.

    2008-12-01

    For a recent lecture, I went to our apparatus stock room and took out our venerable Sargent-Welch projectile apparatus that demonstrates that a dropped ball and a horizontally launched ball hit the floor at the same time, if they are simultaneously released. A problem with this apparatus is that its small size makes it difficult for a large class to see what is going on. Furthermore, the projectiles are ball bearings, which tend to roll under chairs, benches, etc.

  5. Hypervelocity impact survivability experiments for carbonaceous impactors

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, Luann; Bada, Jeffrey; Macklin, John; Radicatidibrozolo, Filippo; Fleming, R. H.; Erlichman, Jozef

    1993-01-01

    We performed a series of hypervelocity impact experiments using carbon-bearing impactors (diamond, graphite, fullerenes, phthalic acid crystals, and Murchison meteorite) into Al plate at velocities between 4.2 and 6.1 km/s. These tests were made to do the following: (1) determine the survivability of carbon forms and organize molecules in low hypervelocity impact; (2) characterize carbonaceous impactor residues; and (3) determine whether or not fullerenes could form from carbonaceous impactors, under our experimental conditions, or survive as impactors. An analytical protocol of field emission SEM imagery, SEM-EDX, laser Raman spectroscopy, single and 2-stage laser mass spectrometry, and laser induced fluorescence (LIF) found the following: (1) diamonds did not survive impact at 4.8 km/s, but were transformed into various forms of disordered graphite; (2) intact, well-ordered graphite impactors did survive impact at 5.9 km/sec, but were only found in the crater bottom centers; the degree of impact-induced disorder in the graphite increases outward (walls, rims, ejecta); (3) phthalic acid crystals were destroyed on impact (at 4.2 km/s, although a large proportion of phthalic acid molecules did survive impact); (4) fullerenes did not form as products of carbonaceous impactors (5.9 - 6.1 km/s, fullerene impactor molecules mostly survived impact at 5.9 km/s; and (5) two Murchison meteorite samples (launched at 4.8 and 5.9 km/s) show preservation of some higher mass polycyclic aromatic hydrocarbons (PAHs) compared with the non-impacted sample. Each impactor type shows unique impactor residue morphologies produced at a given impact velocity. An expanded methodology is presented to announce relatively new analytical techniques together with innovative modifications to other methods that can be used to characterize small impact residues in LDEF craters, in addition to other acquired extraterrestrial samples.

  6. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, Ron; Cotton, Matthew; Harris, Ernest; Eakins, Daniel; Chapman, David

    2013-06-01

    Ramp loading using graded-density-impactors as flyers in plate impact experiments can yield useful information about the dynamic properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to fabricate a graded-density flyer, termed the ``bed of nails'' (BON). A 2 mm thick x 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. Two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at The Institute of Shock Physics, Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in free surface velocity over a period of about 2.5 microseconds. The measured profiles have been analysed to generate a stress vs. volume curve for tantalum.

  7. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, R. E.; Cotton, M.; Harris, E. J.; Chapman, D. J.; Eakins, D.

    2014-05-01

    Ramp loading using graded-density-impactors as flyers in gas-gun-driven plate impact experiments can yield new and useful information about the equation of state and the strength properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to manufacture a graded density flyer, termed the "bed of nails" (BON). A 2 mm thick × 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. The two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at the Institute of Shock Physics at Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, which were mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in velocity over a period of ~2.5 us, with no indication of a shock jump. The measured profiles have been analysed to generate a stress strain curve for tantalum. The results have been compared with the predictions of the Sandia National Laboratories hydrocode, CTH.

  8. The Mass of Large Impactors

    NASA Technical Reports Server (NTRS)

    Parisi, M. G.; Brunini, A.

    1996-01-01

    By means of a simplified dynamical model, we have computed the eccentricity change in the orbit of each giant planet, caused by a single, large impact at the end of the accretion process. In order to set an upper bound on this eccentricity change, we have considered the giant planets' present eccentricities as primordial ones. By means of this procedure, we were able to obtain an implicit relation for the impactor masses and maximum velocities. We have estimated by this method the maximum allowed mass to impact Jupiter to be approx. 1.136 x 10(exp -1), being in the case of Neptune approx. 3.99 x 10(exp -2) (expressed in units of each planet final mass). Due to the similar present eccentricities of Saturn, Uranus and Jupiter, the constraint masses and velocities of the bodies to impact them (in units of each planet final mass and velocity respectively) are almost the same for the three planets. These results are in good agreement with those obtained by Lissauer and Safronov. These bounds might be used to derive the mass distribution of planetesimals in the early solar system.

  9. Jetting during vertical impacts of spherical projectiles

    NASA Astrophysics Data System (ADS)

    Johnson, B. C.; Bowling, T. J.; Melosh, H. J.

    2014-08-01

    The extreme pressures reached during jetting, a process by which material is squirted out from the contact point of two colliding objects, causes melting and vaporization at low impact velocities. Jetting is a major source of melting in shocked porous material, a potential source of tektites, a possible origin of chondrules, and even a conceivable origin of the Moon. Here, in an attempt to quantify the importance of jetting, we present numerical simulation of jetting during the vertical impacts of spherical projectiles on both flat and curved targets. We find that impacts on curved targets result in more jetted material but that higher impact velocities result in less jetted material. For an aluminum impactor striking a flat Al target at 2 km/s we find that 3.4% of a projectile mass is jetted while 8.3% is jetted for an impact between two equal sized Al spheres. Our results indicate that the theory of jetting during the collision of thin plates can be used to predict the conditions when jetting will occur. However, we find current analytic models do not make accurate predictions of the amount of jetted mass. Our work indicates that the amount of jetted mass is independent of model resolution as long as some jetted material is resolved. This is the result of lower velocity material dominating the mass of the jet.

  10. Penetration of yawed projectiles

    SciTech Connect

    Reaugh, J.E.

    1990-10-08

    We used computer simulations and experiment to study the penetration of tungsten-alloy projectiles into a thick, armored steel target. These projectiles, with length-to-diameter ratios of 4, strike the target with severe yaws, up to 90{degree}(side-on-impact), such as might be induced in an originally longer projectile by a multiple-spaced plate array. In this study, we focus on the terminal ballistics of these projectiles and ignore how the yaw was induced. We found that the minimum penetration depth occurs at 90{degree}yaw. This case is well approximated by the two-dimensional plane-strain penetration of a side-on cylinder. The ratio of penetration depth to diameter, P:D, for this case is larger than that for a sphere because the plane-strain geometry lacks hoop stress, which is activated in axisymmetric geometry. A more surprising result of work is that the penetration at 60{degree} yaw is only slightly deeper than that of the side-on impact. 8 refs., 15 figs., 3 tabs.

  11. More on Projectile Motion.

    ERIC Educational Resources Information Center

    Molina, M. I.

    2000-01-01

    Mathematically explains why the range of a projectile is most insensitive to aiming errors when the initial angle is close to 45 degrees, whereas other observables such as maximum height or flight time are most insensitive for near-vertical launching conditions. (WRM)

  12. Projectiles and Aerodynamic Forces.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1984-01-01

    Discusses the air resistance on projectiles, examining (in separate sections) air resistance less than gravity and air resistance greater than gravity. Also considers an approximation in which a trajectory is divided into two parts, the first part neglecting gravity and the second part neglecting the air resistance. (JN)

  13. Dispersion of Projectile and Target Debris Upon Penetration of Thin Targets

    NASA Astrophysics Data System (ADS)

    Gwynn, D.; Bernhard, R. P.; See, T. H.; Horz, F.

    1996-03-01

    We continue to conduct penetration experiments of thin foils to support the development of cosmic-dust flight instruments that utilize thin films for the measurement of particle trajectories, or for the potential soft capture of hypervelocity impactors for subsequent compositional analysis upon retrieval to Earth. Each experiment is equipped with a witness plate, mounted to the rear of the target and fabricated from soft Aluminum-1100, ~30 x 30 cm in size and ranging from 2 to 5 mm thick; these witness plates essentially simulate the rear wall of a capture cell onto which the projectile material will plate out, including material that is being dislodged from the penetrated foil itself. Using compositionally contrasting projectile and foil materials in the laboratory, such as soda-lime glass impactors and aluminum targets, one produces two distinct populations of craters on the witness plates.

  14. Skirted projectiles for railguns

    DOEpatents

    Hawke, R.S.; Susoeff, A.R.

    1994-01-04

    A single skirt projectile (20) having an insulating skirt (22) at its rear, or a dual trailing skirt projectile (30, 40, 50, 60) having an insulating skirt (32, 42, 52, 62) succeeded by an arc extinguishing skirt (34, 44, 54, 64), is accelerated by a railgun accelerator 10 having a pair of parallel conducting rails (1a, 1b) which are separated by insulating wall spacers (11). The insulating skirt (22, 32, 42, 52, 62) includes a plasma channel (38). The arc extinguishing skirt (34, 44, 54, 64) interrupts the conduction that occurs in the insulating skirt channel (38) by blocking the plasma arc (3) from conducting current from rail to rail (1a, 1b) at the rear of the projectile (30, 40, 50, 60). The arc extinguishing skirt may be comprised of two plates (36a, 36b) which form a horseshoe wherein the plates are parallel to the rails (1a, b); a chisel-shape design; cross-shaped, or it may be a cylindrical (64). The length of the insulating skirt channel is selected such that there is sufficient plasma in the channel to enable adequate current conduction between the rails (1a, 1b).

  15. Skirted projectiles for railguns

    DOEpatents

    Hawke, Ronald S.; Susoeff, Allan R.

    1994-01-01

    A single skirt projectile (20) having an insulating skirt (22) at its rear, or a dual trailing skirt projectile (30, 40, 50, 60) having an insulating skirt (32, 42, 52, 62) succeeded by an arc extinguishing skirt (34, 44, 54, 64), is accelerated by a railgun accelerator 10 having a pair of parallel conducting rails (1a, 1b) which are separated by insulating wall spacers (11). The insulating skirt (22, 32, 42, 52, 62) includes a plasma channel (38). The arc extinguishing skirt (34, 44, 54, 64) interrupts the conduction that occurs in the insulating skirt channel (38) by blocking the plasma arc (3) from conducting current from rail to rail (1a, 1b) at the rear of the projectile (30, 40, 50, 60). The arc extinguishing skirt may be comprised of two plates (36a, 36b) which form a horseshoe wherein the plates are parallel to the rails (1a, b); a chisel-shape design; cross-shaped, or it may be a cylindrical (64). The length of the insulating skirt channel is selected such that there is sufficient plasma in the channel to enable adequate current conduction between the rails (1a, 1b).

  16. The Canyon Diablo impact event: Projectile motion through the atmosphere

    NASA Astrophysics Data System (ADS)

    Artemieva, N.; Pierazzo, E.

    2009-03-01

    Meteor Crater is one of the first impact structures systematically studied on Earth. Its location in arid northern Arizona has been ideal for the preservation of the structure and the surviving meteoric material. The recovery of a large amount of meteoritic material in and around the crater has allowed a rough reconstruction of the impact event: an iron object 50 m in diameter impacted the Earth’s surface after breaking up in the atmosphere. The details of the disruption, however, are still debated. The final crater morphology (deep, bowl-shaped crater) rules out the formation of the crater by an open or dispersed swarm of fragments, in which the ratio of swarm radius to initial projectile radius Cd is larger than 3 (the final crater results from the sum of the craters formed by individual fragments). On the other hand, the lack of significant impact melt in the crater has been used to suggest that the impactor was slowed down to 12 km/s by the atmosphere, implying significant fragmentation and fragments’ separation up to 4 initial radii. This paper focuses on the problem of entry and motion through the atmosphere for a possible Canyon Diablo impactor as a first but necessary step for constraining the initial conditions of the impact event which created Meteor Crater. After evaluating typical models used to investigate meteoroid disruption, such as the pancake and separated fragment models, we have carried out a series of hydrodynamic simulations using the 3D code SOVA to model the impactor flight through the atmosphere, both as a continuum object and a disrupted swarm. Our results indicate that the most probable pre-atmospheric mass of the Meteor Crater projectile was in the range of 4ṡ108 to 1.2ṡ109 kg (equivalent to a sphere 46-66 m in diameter). During the entry process the projectile lost probably 30% to 70% of its mass, mainly because of mechanical ablation and gross fragmentation. Even in the case of a tight swarm of particles (Cd <3), small

  17. Direct detection of projectile relics from the end of the lunar basin-forming epoch.

    PubMed

    Joy, Katherine H; Zolensky, Michael E; Nagashima, Kazuhide; Huss, Gary R; Ross, D Kent; McKay, David S; Kring, David A

    2012-06-15

    The lunar surface, a key proxy for the early Earth, contains relics of asteroids and comets that have pummeled terrestrial planetary surfaces. Surviving fragments of projectiles in the lunar regolith provide a direct measure of the types and thus the sources of exogenous material delivered to the Earth-Moon system. In ancient [>3.4 billion years ago (Ga)] regolith breccias from the Apollo 16 landing site, we located mineral and lithologic relics of magnesian chondrules from chondritic impactors. These ancient impactor fragments are not nearly as diverse as those found in younger (3.4 Ga to today) regolith breccias and soils from the Moon or that presently fall as meteorites to Earth. This suggests that primitive chondritic asteroids, originating from a similar source region, were common Earth-Moon-crossing impactors during the latter stages of the basin-forming epoch. PMID:22604725

  18. Projectile penetration into representative targets

    NASA Astrophysics Data System (ADS)

    Stone, George W.

    1994-10-01

    The differential equation representing the penetration of a 'hard' projectile into semi-infinite, homogeneous target materials is solved for several generic combinations of the target material/projectile characteristics. A 'hard' projectile is defined as one that does not change size or shape and does not lose mass during the penetration process. The target materials evaluated range from the structurally 'soft' materials (liquids) to structurally 'hard' materials (armor plate) with viscous and fluid dynamic drag considered. The solutions to the differential equation(s) are expanded in series form to demonstrate the underlying parameters governing projectile penetration and the way they interact to limit penetration in a given target material. It is shown that the fundamental parameter governing projectile penetration into structurally 'firm' materials is the initial kinetic energy of the projectile divided by the frontal area of the projectile and the inherent structural characteristic of the target. Experimental data on the penetration of steel spheres into ballistic gelatin and for armor piercing bullets into armor plate materials are used to verify the characteristics of the solutions to the equation of motion for the projectile and to demonstrate how penetration can vary with projectile size and target characteristics. The penetration equation for a single 'hard' target material is used to develop a solution for the penetration of multilayered 'hard' target materials.

  19. Implications of asteroid composition for the geochemistry of the ancient terrestrial projectile flux

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey F.

    1988-01-01

    The discovery of enhanced siderophile abundances at the Cretaceous/Tertiary boundary has provoked many searches for geochemical signatures which could reveal other catastrophic impacts in Earth's history. These searches implicitly assume that most large impactors are of chondritic, iron, or stony-iron composition, with a greatly enhanced abundance of siderophile elements. Impactors composed of asteroidal crust or mantle rocks analogous to the achondritic meteorites would not leave a distinct geochemical trace since their siderophile abundances are grossly similar to those of the Earth's crust. In recent years studies of the mineralogical composition of the current asteroid belt have suggested that the composition of impacting projectiles may be highly variable with both projectile size and time. In particular it seems possible that in the distant past projectiles derived from asteroid mantle material may have caused a large fraction of the cratering events on Earth. Such impacts would be missed by any geochemical search relying on iridium or any other siderophile element. The questions of the effect of size and time variations on projectile composition and the significance of hidden impacts missing in current geochemical searches are examined.

  20. Geochemical processes between steel projectiles and silica-rich targets in hypervelocity impact experiments

    NASA Astrophysics Data System (ADS)

    Ebert, Matthias; Hecht, Lutz; Deutsch, Alexander; Kenkmann, Thomas; Wirth, Richard; Berndt, Jasper

    2014-05-01

    The possibility of fractionation processes between projectile and target matter is critical with regard to the classification of the impactor type from geochemical analysis of impactites from natural craters. Here we present results of five hypervelocity MEMIN impact experiments (Poelchau et al., 2013) using the Cr-V-Co-Mo-W-rich steel D290-1 as projectile and two different silica-rich lithologies (Seeberger sandstone and Taunus quartzite) as target materials. Our study is focused on geochemical target-projectile interaction occurring in highly shocked and projectile-rich ejecta fragments. In all of the investigated impact experiments, whether sandstone or quartzite targets, the ejecta fragments show (i) shock-metamorphic features e.g., planar-deformation features (PDF) and the formation of silica glasses, (ii) partially melting of projectile and target, and (iii) significant mechanical and chemical mixing of the target rock with projectile material. The silica-rich target melts are strongly enriched in the "projectile tracer elements" Cr, V, and Fe, but have just minor enrichments of Co, W, and Mo. Inter-element ratios of these tracer elements within the contaminated target melts differ strongly from the original ratios in the steel. The fractionation results from differences in the reactivity of the respective elements with oxygen during interaction of the metal melt with silicate melt. Our results indicate that the principles of projectile-target interaction and associated fractionation do not depend on impact energies (at least for the selected experimental conditions) and water-saturation of the target. Partitioning of projectile tracer elements into the silicate target melt is much more enhanced in experiments with a non-porous quartzite target compared with the porous sandstone target. This is mainly the result of higher impact pressures, consequently higher temperatures and longer reaction times at high temperatures in the experiments with quartzite as

  1. Next generation pharmaceutical impactor (a new impactor for pharmaceutical inhaler testing). Part II: Archival calibration.

    PubMed

    Marple, Virgil A; Olson, Bernard A; Santhanakrishnan, Kumaragovindham; Mitchell, Jolyon P; Murray, Sharon C; Hudson-Curtis, Buffy L

    2003-01-01

    A new seven-stage cascade impactor, the Next Generation Pharmaceutical Impactor (NGI), has been developed for the pharmaceutical industry. A calibration following "good laboratory practice (GLP)" procedures has been performed on a specific archival NGI, deemed to be representative of all NGIs. Thus, this impactor had nozzle dimensions for each stage manufactured close to the middle of the tolerance band for the design specification, and therefore the average nozzle diameter was equal to the nominal value for that stage. An essential feature of the NGI is that it is designed to operate at any flow rate between 30 and 100 L/min. Thus, the calibration was made at inlet flow rates of 30, 60 and 100 L/min representing the lower bound, mid-region and upper bound of the specified range of operation for the impactor. The calibration data were then used to develop equations that predict the particle cut size for all components of the impactor at any flow rate from 30 to 100 L/min.

  2. Ballistic projectile trajectory determining system

    DOEpatents

    Karr, T.J.

    1997-05-20

    A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile. 8 figs.

  3. Ballistic projectile trajectory determining system

    DOEpatents

    Karr, Thomas J.

    1997-01-01

    A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile.

  4. Evaluation of different projectiles in matched experimental eye impact simulations.

    PubMed

    Weaver, Ashley A; Kennedy, Eric A; Duma, Stefan M; Stitzel, Joel D

    2011-03-01

    Eye trauma results in 30,000 cases of blindness each year in the United States and is the second leading cause of monocular visual impairment. Eye injury is caused by a wide variety of projectile impacts and loading scenarios with common sources of trauma being motor vehicle crashes, military operations, and sporting impacts. For the current study, 79 experimental eye impact tests in literature were computationally modeled to analyze global and localized responses of the eye to a variety of blunt projectile impacts. Simulations were run with eight different projectiles (airsoft pellets, baseball, air gun pellets commonly known as BBs, blunt impactor, paintball, aluminum, foam, and plastic rods) to characterize effects of the projectile size, mass, geometry, material properties, and velocity on eye response. This study presents a matched comparison of experimental test results and computational model outputs including stress, energy, and pressure used to evaluate risk of eye injury. In general, the computational results agreed with the experimental results. A receiver operating characteristic curve analysis was used to establish the stress and pressure thresholds that best discriminated for globe rupture in the matched experimental tests. Globe rupture is predicted by the computational simulations when the corneoscleral stress exceeds 17.21 MPa or the vitreous pressure exceeds 1.01 MPa. Peak stresses were located at the apex of the cornea, the limbus, or the equator depending on the type of projectile impacting the eye. A multivariate correlation analysis revealed that area-normalized kinetic energy was the best single predictor of peak stress and pressure. Additional incorporation of a relative size parameter that relates the projectile area to the area of the eye reduced stress response variability and may be of importance in eye injury prediction. The modeling efforts shed light on the injury response of the eye when subjected to a variety of blunt projectile

  5. Evaluation of different projectiles in matched experimental eye impact simulations.

    PubMed

    Weaver, Ashley A; Kennedy, Eric A; Duma, Stefan M; Stitzel, Joel D

    2011-03-01

    Eye trauma results in 30,000 cases of blindness each year in the United States and is the second leading cause of monocular visual impairment. Eye injury is caused by a wide variety of projectile impacts and loading scenarios with common sources of trauma being motor vehicle crashes, military operations, and sporting impacts. For the current study, 79 experimental eye impact tests in literature were computationally modeled to analyze global and localized responses of the eye to a variety of blunt projectile impacts. Simulations were run with eight different projectiles (airsoft pellets, baseball, air gun pellets commonly known as BBs, blunt impactor, paintball, aluminum, foam, and plastic rods) to characterize effects of the projectile size, mass, geometry, material properties, and velocity on eye response. This study presents a matched comparison of experimental test results and computational model outputs including stress, energy, and pressure used to evaluate risk of eye injury. In general, the computational results agreed with the experimental results. A receiver operating characteristic curve analysis was used to establish the stress and pressure thresholds that best discriminated for globe rupture in the matched experimental tests. Globe rupture is predicted by the computational simulations when the corneoscleral stress exceeds 17.21 MPa or the vitreous pressure exceeds 1.01 MPa. Peak stresses were located at the apex of the cornea, the limbus, or the equator depending on the type of projectile impacting the eye. A multivariate correlation analysis revealed that area-normalized kinetic energy was the best single predictor of peak stress and pressure. Additional incorporation of a relative size parameter that relates the projectile area to the area of the eye reduced stress response variability and may be of importance in eye injury prediction. The modeling efforts shed light on the injury response of the eye when subjected to a variety of blunt projectile

  6. Penetration experiments in aluminum 1100 targets using soda-lime glass projectiles

    NASA Technical Reports Server (NTRS)

    Horz, Friedrich; Cintala, Mark J.; Bernhard, Ronald P.; Cardenas, Frank; Davidson, William E.; Haynes, Gerald; See, Thomas H.; Winkler, Jerry L.

    1995-01-01

    The cratering and penetration behavior of annealed aluminum 1100 targets, with thickness varied from several centimeters to ultra-thin foils less than 1 micrometer thick, were experimentally investigated using 3.2 mm diameter spherical soda-lime glass projectiles at velocities from 1 to 7 km/s. The objective was to establish quantitative, dimensional relationships between initial impact conditions (impact velocity, projectile diameter, and target thickness) and the diameter of the resulting crater or penetration hole. Such dimensional relationships and calibration experiments are needed to extract the diameters and fluxes of hypervelocity particles from space-exposed surfaces and to predict the performance of certain collisional shields. The cratering behavior of aluminum 1100 is fairly well predicted. However, crater depth is modestly deeper for our silicate impactors than the canonical value based on aluminum projectiles and aluminum 6061-T6 targets. The ballistic-limit thickness was also different. These differences attest to the great sensitivity of detailed crater geometry and penetration behavior on the physical properties of both the target and impactor. Each penetration experiment was equipped with a witness plate to monitor the nature of the debris plume emanating from the rear of the target. This plume consists of both projectile fragments and target debris. Both penetration hole and witness-plate spray patterns systematically evolve in response to projectile diameter/target thickness. The relative dimensions of the projectile and target totally dominate the experimental products documented in this report; impact velocity is an important contributor as well to the evolution of penetration holes, but is of subordinate significance for the witness-plate spray patterns.

  7. An impactor origin for lunar magnetic anomalies.

    PubMed

    Wieczorek, Mark A; Weiss, Benjamin P; Stewart, Sarah T

    2012-03-01

    The Moon possesses strong magnetic anomalies that are enigmatic given the weak magnetism of lunar rocks. We show that the most prominent grouping of anomalies can be explained by highly magnetic extralunar materials from the projectile that formed the largest and oldest impact crater on the Moon: the South Pole-Aitken basin. The distribution of projectile materials from a model oblique impact coincides with the distribution of magnetic anomalies surrounding this basin, and the magnetic properties of these materials can account for the intensity of the observed anomalies if they were magnetized in a core dynamo field. Distal ejecta from this event can explain the origin of isolated magnetic anomalies far from this basin.

  8. La masa de los grandes impactores

    NASA Astrophysics Data System (ADS)

    Parisi, M. G.; Brunini, A.

    Los planetas han sido formados fundamentalmente acretando masa a través de colisiones con planetesimales sólidos. La masa más grande de la distribución de planetesimales y las masas máxima y mínima de los impactores, han sido calculadas usando los valores actuales del período y de la inclinación de los planetas (Lissauer & Safronov 1991; Parisi & Brunini 1996). Recientes investigaciones han mostrado, que las órbitas de los planetas gigantes no han sufrido variaciones con el tiempo, siendo su movimiento regular durante su evolución a partir de la finalización de la etapa de acreción (Laskar 1990, 1994). Por lo tanto, la eccentricidad actual de los planetas gigantes se puede utilizar para imponer una cota máxima a las masas y velocidades orbitales de los grandes impactores. Mediante un simple modelo dinámico, y considerando lo arriba mencionado, obtenemos la cota superior para la masa del planetesimal más grande que impactó a cada planeta gigante al final de su etapa de acreción. El resultado más importante de este trabajo es la estimación de la masa máxima permitida para impactar a Júpiter, la cúal es ~ 1.136 × 10 -1, siendo en el caso de Neptuno ~ 3.99 × 10 -2 (expresada en unidades de la masa final de cada planeta). Además, fue posible obtener la velocidad orbital máxima permitida para los impactores como una función de su masa, para cada planeta. Las cotas obtenidas para la masa y velocidad de los impactores de Saturno y Urano (en unidades de la masa y velocidad final de cada planeta respectivamente) son casi las mismas que las obtenidas para Júpiter debido a que estos tres planetas poseen similar eccentricidad actual. Nuestros resultados están en buen acuerdo con los obtenidos por Lissauer & Safronov (1991). Estas cotas podrían ser utilizadas para obtener la distribución de planetesimales en el Sistema Solar primitivo.

  9. Asteroid deflection using a kinetic impactor: Insights from hypervelocity impact experiments

    NASA Astrophysics Data System (ADS)

    Hoerth, Tobias; Schäfer, Frank

    2016-04-01

    Within the framework of the planned AIDA mission [1], an impactor spacecraft (DART) hits the second component of the asteroid Didymos at hypervelocity. The impact crater will be observed from the AIM spacecraft and an observation of the ejecta plume is possible [1]. This allows conclusions to be drawn about the physical properties of the target material, and the momentum transfer will be studied [1]. In preparation for this mission, hypervelocity impact experiments can provide valuable information about the outcome of an impact event as a function of impactor and target material properties and, thus, support the interpretation of the data from the DART impact. In addition, these impact experiments provide an important means to validate numerical impact simulations required to simulate large-scale impacts that cannot be studied in laboratory experiments. Impact experiments have shown that crater morphology and size, crater growth and ejecta dynamics strongly depend on the physical properties of the target material [2]. For example, porous materials like sandstone lead to a shallower and slower ejection than low-porous materials like quartzite, and the cratering efficiency is reduced in porous targets leading to a smaller amount of ejected mass [3]. These phenomena result in a reduced momentum multiplication factor (often called "beta-value"), i.e. the ratio of the change in target momentum after the impact and the momentum of the projectile is smaller for porous materials. Hypervelocity impact experiments into target materials with different porosities and densities such as quartzite (2.9 %, 2.6 g/cm3), sandstone (25.3 %, 2 g/cm3), limestone (31 %, 1.8 g/cm3), and highly porous aerated concrete (87.5 %, 0.4 g/cm3) were conducted. Projectile velocities were varied between about 3 km/s and almost 7 km/s. A ballistic pendulum was used to measure the momentum transfer. The material strength required for scaling laws was determined for all target materials. The highest

  10. Grooved impactor and inertial trap for sampling inhalable particulate matter

    DOEpatents

    Loo, Billy W.

    1984-01-01

    An inertial trap and grooved impactor for providing a sharp cutoff for particles over 15 microns from entering an inhalable particulate sampler. The impactor head has a tapered surface and is provided with V-shaped grooves. The tapered surface functions for reducing particle blow-off or reentrainment while the grooves prevent particle bounce. Water droplets and any resuspended material over the 15 micron size are collected by the inertial trap and deposited in a reservoir associated with the impactor.

  11. Analytical electron microscopy of LDEF impactor residues

    NASA Technical Reports Server (NTRS)

    Bernhard, Ronald P.; Barrett, Ruth A.; Zolensky, Michael E.

    1995-01-01

    The LDEF contained 57 individual experiment trays or tray portions specifically designed to characterize critical aspects of meteoroid and debris environment in low-Earth orbit (LEO). However, it was realized from the beginning that the most efficient use of the satellite would be to characterize impact features from the entire surface of the LDEF. With this in mind particular interest has focused on common materials facing in all 26 LDEF facing directions; among the most important of these materials has been the tray clamps. Therefore, in an effort to better understand the nature and flux of particulates in LEO, and their effects on spacecraft hardware, we are analyzing residues found in impact features on LDEF tray clamp surfaces. This paper summarizes all data from 79 clamps located on Bay A & B of the LDEF. We also describe current efforts to characterize impactor residues recovered from the impact craters, and we have found that a low, but significant, fraction of these residues have survived in a largely unmelted state. These residues can be characterized sufficiently to permit resolution of the impactor origin. We have concentrated on the residue from chondritic interplanetary dust particles (micrometeoroids), as these represent the harshest test of our analytical capabilities.

  12. Quantitative analysis of cascade impactor samples - revisited

    NASA Astrophysics Data System (ADS)

    Orlić , I.; Chiam, S. Y.; Sanchez, J. L.; Tang, S. M.

    1999-04-01

    Concentrations of aerosols collected in Singapore during the three months long haze period that affected the whole South-East Asian region in 1997 are reported. Aerosol samples were continuously collected by using a fine aerosol sampler (PM2.5) and occasionally with a single orifice cascade impactor (CI) sampler. Our results show that in the fine fraction (<2.5 μm) the concentrations of two well-known biomass burning products, i.e. K and S were generally increased by a factor 2-3 compared to the non-hazy periods. However, a discrepancy was noticed, at least for elements with lower atomic number (Ti and below) between the results obtained by the fine aerosol sampler and the cascade impactor. Careful analysis by means of Nuclear Microscopy, in particular by the Scanning Transmission Ion Microscopy (STIM) technique, revealed that thicknesses of the lower CI stages exceeded thick target limits for 2 MeV protons. Detailed depth profiles of all CI stages were therefore measured using the STIM technique and concentrations corrected for absorption and proton energy loss. After correcting results for the actual sample thickness, concentrations of all major elements (S, Cl, K, Ca) agreed much better with the PM2.5 results. The importance of implementing thick target corrections in analysis of CI samples, especially those collected in the urban environments, is emphasized. Broad beam PIXE analysis approach is certainly not adequate in these cases.

  13. Air-Powered Projectile Launcher

    NASA Technical Reports Server (NTRS)

    Andrews, T.; Bjorklund, R. A.; Elliott, D. G.; Jones, L. K.

    1987-01-01

    Air-powered launcher fires plastic projectiles without using explosive propellants. Does not generate high temperatures. Launcher developed for combat training for U.S. Army. With reservoir pressurized, air launcher ready to fire. When pilot valve opened, sleeve (main valve) moves to rear. Projectile rapidly propelled through barrel, pushed by air from reservoir. Potential applications in seismic measurements, avalanche control, and testing impact resistance of windshields on vehicles.

  14. Projectile penetration into ballistic gelatin.

    PubMed

    Swain, M V; Kieser, D C; Shah, S; Kieser, J A

    2014-01-01

    Ballistic gelatin is frequently used as a model for soft biological tissues that experience projectile impact. In this paper we investigate the response of a number of gelatin materials to the penetration of spherical steel projectiles (7 to 11mm diameter) with a range of lower impacting velocities (<120m/s). The results of sphere penetration depth versus projectile velocity are found to be linear for all systems above a certain threshold velocity required for initiating penetration. The data for a specific material impacted with different diameter spheres were able to be condensed to a single curve when the penetration depth was normalised by the projectile diameter. When the results are compared with a number of predictive relationships available in the literature, it is found that over the range of projectiles and compositions used, the results fit a simple relationship that takes into account the projectile diameter, the threshold velocity for penetration into the gelatin and a value of the shear modulus of the gelatin estimated from the threshold velocity for penetration. The normalised depth is found to fit the elastic Froude number when this is modified to allow for a threshold impact velocity. The normalised penetration data are found to best fit this modified elastic Froude number with a slope of 1/2 instead of 1/3 as suggested by Akers and Belmonte (2006). Possible explanations for this difference are discussed.

  15. Projectile penetration into ballistic gelatin.

    PubMed

    Swain, M V; Kieser, D C; Shah, S; Kieser, J A

    2014-01-01

    Ballistic gelatin is frequently used as a model for soft biological tissues that experience projectile impact. In this paper we investigate the response of a number of gelatin materials to the penetration of spherical steel projectiles (7 to 11mm diameter) with a range of lower impacting velocities (<120m/s). The results of sphere penetration depth versus projectile velocity are found to be linear for all systems above a certain threshold velocity required for initiating penetration. The data for a specific material impacted with different diameter spheres were able to be condensed to a single curve when the penetration depth was normalised by the projectile diameter. When the results are compared with a number of predictive relationships available in the literature, it is found that over the range of projectiles and compositions used, the results fit a simple relationship that takes into account the projectile diameter, the threshold velocity for penetration into the gelatin and a value of the shear modulus of the gelatin estimated from the threshold velocity for penetration. The normalised depth is found to fit the elastic Froude number when this is modified to allow for a threshold impact velocity. The normalised penetration data are found to best fit this modified elastic Froude number with a slope of 1/2 instead of 1/3 as suggested by Akers and Belmonte (2006). Possible explanations for this difference are discussed. PMID:24184862

  16. Asteroid Impact & Deflection Assessment mission: Kinetic impactor

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Michel, P.; Jutzi, M.; Rivkin, A. S.; Stickle, A.; Barnouin, O.; Ernst, C.; Atchison, J.; Pravec, P.; Richardson, D. C.

    2016-02-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid. AIDA is an international cooperation, consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the ESA Asteroid Impact Mission (AIM) rendezvous mission. The primary goals of AIDA are (i) to test our ability to perform a spacecraft impact on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary near-Earth asteroid (65803) Didymos, with the deflection experiment to occur in late September, 2022. The DART impact on the secondary member of the binary at ~7 km/s is expected to alter the binary orbit period by about 4 minutes, assuming a simple transfer of momentum to the target, and this period change will be measured by Earth-based observatories. The AIM spacecraft will characterize the asteroid target and monitor results of the impact in situ at Didymos. The DART mission is a full-scale kinetic impact to deflect a 150 m diameter asteroid, with known impactor conditions and with target physical properties characterized by the AIM mission. Predictions for the momentum transfer efficiency of kinetic impacts are given for several possible target types of different porosities, using Housen and Holsapple (2011) crater scaling model for impact ejecta mass and velocity distributions. Results are compared to numerical simulation results using the Smoothed Particle Hydrodynamics code of Jutzi and Michel (2014) with good agreement. The model also predicts that the ejecta from the DART impact may make Didymos into an active asteroid, forming an ejecta coma that may be observable from Earth-based telescopes. The measurements from AIDA of the momentum transfer from the DART impact, the crater size and morphology, and the evolution of an ejecta coma will

  17. Two-dimensional virtual impactors. Final report

    SciTech Connect

    Forney, L.J.; Ravenhall, D.G.

    1980-12-01

    Theoretical predictions using both potential flow analyses and solutions to Navier-Stokes equations are made for the operating characteristics of a two-dimensional virtual impactor. Experiments were performed with 2.5 ..mu..m, uranine tagged, di-octylphthalate (DOP) oil droplets for a wide range of prototype geometries to measure the magnitude of internal losses and to fully characterize the instrument response. The influence of geometry including the throat angle (38/sup 0/ less than or equal to ..beta../sub 0/ less than or equal to 58.2/sup 0/) and normalized void width (0.7 less than or equal to h/w less than or equal to 1.5) on the particle cutoff diameter, efficiency curve steepness and properties of the internal particle loss factor are presented for fixed instrument Reynolds numbers Re = 1540 and bleed flow f = 0.1. The theory, supported by trends in the empirical data, predicts that internal particle losses reduce to zero as the normalized void width increases to h/w = 1.4 +- .1 while the data show a minimum at h/w = 1.6 +- .1. Increasing the void width, however, is shown to substantially reduce the steepness of the particle efficiency curves. Visual observations of the onset of fluid separation for two-dimensional jets impinging upon a void were conducted with a scaled-up water model and correlated with theory. It was found that the limiting void width h/sub lim//w marking the onset of fluid instabilities peaked for an intermediate value of the fluid deflecting plate angle ..beta.. approx. = 80/sup 0/ with larger values of h/sub lim//w corresponding to smaller throat angles ..beta../sub 0/. The limiting void width h/sub lim//w also increased with larger bleed flows into the void. These instabilities may make it difficult to correlate experimental virtual impactor data with theory.

  18. Icy Satellites Impactor Probes for the Jovian Icy Moons Orbiter

    NASA Technical Reports Server (NTRS)

    Shirley, J. H.; Zimmerman, W. F.; Strauss, W.; Ivlev, R.; Duong, T.; Hunter, D.; Slimko, E.; Nacaise, F.; Archer, E.; Nesmith, B.

    2003-01-01

    We present a preliminary design and mission description for Icy Satellites Impactor Probes (IPS). This design addresses two of the scientific themes of this Icy Galilean Satellites Forum: Surface Chemistry and Geophysics, and Interior Structures. Impactor probes may also make significant contributions in the areas of surface geology and mineralogy.

  19. Prevention of breakdown behind railgun projectiles

    DOEpatents

    Hawke, Ronald S.

    1992-01-01

    An electromagnetic railgun accelerator system, for accelerating projectiles (14, 15, 114, 214, 314, 444) by a plasma arc (3), introduces a breakdown inhibiting gas into the railgun chamber (26) behind the accelerating projectile (14). The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF.sub.6. The gas is introduced between the railgun rails (12) after the projectile (14) has passed through inlets (16) in the rails (12) or the projectile (114); by coating the rails (12) or the projectile (15) with a material (28) which releases the gas after the projectile (14 ) passes over it; by fabricating the rails (12) or the projectile (15) or insulators out of a material which releases the gas into the portions of the chamber (26) through which the projectile has travelled. The projectile (214, 314, 414) may have a cavity (232, 332, 432) at its rear to control the release of ablation products (4).

  20. Prevention of breakdown behind railgun projectiles

    DOEpatents

    Hawke, Ronald S.

    1992-01-01

    An electromagnetic railgun accelerator system, for accelerating projectiles (14, 15, 114, 214, 314, 414) by a plasma arc (3), introduces a breakdown inhibiting gas into the railgun chamber (26) behind the accelerating projectile (14). The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF.sub.6. The gas is introduced between the railgun rails (12) after the projectile (14) has passed through inlets (16) in the rails (12) or the projectile (114); by coating the rails (12) or the projectile (15) with a material (28) which releases the gas after the projectile (14) passes over it; by fabricating the rails (12) or the projectile (15) or insulators out of a material which releases the gas into the portions of the chamber (26) through which the projectile has travelled. The projectile (214, 314, 414) may have a cavity (232, 332, 432) at its rear to control the release of ablation products (4).

  1. Prevention of breakdown behind railgun projectiles

    DOEpatents

    Hawke, R.S.

    1992-09-01

    An electromagnetic railgun accelerator system, for accelerating projectiles by a plasma arc, introduces a breakdown inhibiting gas into the railgun chamber behind the accelerating projectile. The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF[sub 6]. The gas is introduced between the railgun rails after the projectile has passed through inlets in the rails or the projectile; by coating the rails or the projectile with a material which releases the gas after the projectile passes over it; by fabricating the rails or the projectile or insulators out of a material which releases the gas into the portions of the chamber through which the projectile has travelled. The projectile may have a cavity at its rear to control the release of ablation products. 12 figs.

  2. Prevention of breakdown behind railgun projectiles

    DOEpatents

    Hawke, R.S.

    1992-10-13

    An electromagnetic railgun accelerator system, for accelerating projectiles by a plasma arc, introduces a breakdown inhibiting gas into the railgun chamber behind the accelerating projectile. The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF[sub 6]. The gas is introduced between the railgun rails after the projectile has passed through inlets in the rails or the projectile; by coating the rails or the projectile with a material which releases the gas after the projectile passes over it; by fabricating the rails or the projectile or insulators out of a material which releases the gas into the portions of the chamber through which the projectile has travelled. The projectile may have a cavity at its rear to control the release of ablation products. 12 figs.

  3. Combustion modes around hypersonic projectiles

    NASA Astrophysics Data System (ADS)

    Kamel, Michel Roger

    This work provides new experiments which detail the flow field characteristics around a blunt projectile traveling hypersonically in a reactive mixture using simultaneous planar laser-induced fluoresence and schlieren imaging, and stagnation pressure history measurements. The flow fields are generated using an expansion tube facility which accelerates a reactive mixture to supersonic speeds. The physical characteristics and the performance of the expansion tube are discussed. A blunt projectile is fixed at the exit of the tube and laser-based diagnostics are used to image the resulting combustion. Experimental results obtained here as well as results obtained from the literature suggest that for steady combustion to occur in supersonic reactive flow fields two conditions must be satisfied: (1) the post-shock induction time along the stagnation line should be much smaller than the time required for the shocked particles to reach the body; (2) the flow velocity relative to the projectile has to be larger than the mixture's Chapman-Jouget detonation velocity. For the unsteady flows, the measured frequency of oscillations decreases with increasing body diameter, mixture sensitivity, and free stream pressure. Dimensional analysis of the experimental results suggests that the dominant oscillations are due to disturbances reflecting off the cylinder body, in agreement with models proposed previously. Analogies are made between the flow fields observed in these experiments and those of 1-D pulsed detonations, and deflagration to detonation transitions. A theory for prediction of detonation initiation by blunted projectiles traveling at the Chapman-Jouget detonation speeds is modified here to be applicable to projectiles traveling at lower velocities. The modified theory is used to identify the boundaries of the different combustion modes as a function of projectile Mach number and mixture initial pressure. Results from the ballistic range experiments, computational fluid

  4. Target and Projectile: Material Effects on Crater Excavation and Growth

    NASA Technical Reports Server (NTRS)

    Anderson, J. L. B.; Burleson, T.; Cintala, Mark J.

    2010-01-01

    Scaling relationships allow the initial conditions of an impact to be related to the excavation flow and final crater size and have proven useful in understanding the various processes that lead to the formation of a planetary-scale crater. In addition, they can be examined and tested through laboratory experiments in which the initial conditions of the impact are known and ejecta kinematics and final crater morphometry are measured directly. Current scaling relationships are based on a point-source assumption and treat the target material as a continuous medium; however, in planetary-scale impacts, this may not always be the case. Fragments buried in a megaregolith, for instance, could easily approach or exceed the dimensions of the impactor; rubble-pile asteroids could present similar, if not greater, structural complexity. Experiments allow exploration into the effects of target material properties and projectile deformation style on crater excavation and dimensions. This contribution examines two of these properties: (1) the deformation style of the projectile, ductile (aluminum) or brittle (soda-lime glass) and (2) the grain size of the target material, 0.5-1 mm vs. 1-3 mm sand.

  5. Projectile-generating explosive access tool

    SciTech Connect

    Jakaboski, Juan-Carlos; Hughs, Chance G; Todd, Steven N

    2013-06-11

    A method for generating a projectile using an explosive device that can generate a projectile from the opposite side of a wall from the side where the explosive device is detonated. The projectile can be generated without breaching the wall of the structure or container. The device can optionally open an aperture in a solid wall of a structure or a container and form a high-kinetic-energy projectile from the portion of the wall removed to create the aperture.

  6. Novice Rules for Projectile Motion.

    ERIC Educational Resources Information Center

    Maloney, David P.

    1988-01-01

    Investigates several aspects of undergraduate students' rules for projectile motion including general patterns; rules for questions about time, distance, solids and liquids; and changes in rules when asked to ignore air resistance. Reports approach differences by sex and high school physics experience, and that novice rules are situation…

  7. Electrical analog to projectile motion

    NASA Astrophysics Data System (ADS)

    Vondracek, Mark

    1998-04-01

    This article describes an electrical analog to traditional projectile problems given in high school and introductory college classes. It also discusses the importance of stressing the understanding of physical laws and principles to students, and that the physics behind a problem is more important than being able to memorize and use various equations.

  8. Projectile Motion Gets the Hose

    ERIC Educational Resources Information Center

    Goff, John Eric; Liyanage, Chinthaka

    2011-01-01

    Students take a weekly quiz in our introductory physics course. During the week in which material focused on projectile motion, we not-so-subtly suggested what problem the students would see on the quiz. The quiz problem was an almost exact replica of a homework problem we worked through in the class preceding the quiz. The goal of the problem is…

  9. Having Fun with a 3-D Projectile

    ERIC Educational Resources Information Center

    Lammi, Matthew; Greenhalgh, Scott

    2011-01-01

    The use of projectiles is a concept familiar to most students, whether it is a classic slingshot, bow and arrow, or even a spit wad through a straw. Perhaps the last thing a teacher wants is more projectiles in the classroom. However, the concept of projectiles is relevant to most students and may provide a means of bringing more authenticity into…

  10. Atmospheric behavior of the Chelyabinsk impactor

    NASA Astrophysics Data System (ADS)

    Borovička, J.; Spurný, P.; Brown, P.; Kalenda, P.; Shrbený, L.

    2014-07-01

    The impact of a 19-m diameter asteroid near Chelyabinsk, Russia on February 15, 2013 has already been studied extensively [e.g., 1--3]. The main sources of information were casually recorded videos, which provided the images of the superbolide as well as acoustic records of the sonic booms. From these data, the bolide trajectory, velocity, deceleration, and lightcurve have been derived after careful calibration and analysis. Such detailed data are not available for any other impactor larger than about 5 meters. The Chelyabinsk event represents therefore a unique opportunity to study the interaction of asteroids in the decameter size range through the terrestrial atmosphere. In comparison with our previous study [1], we used more calibrated videos in this work. We will present the refined trajectory, velocity, and orbit but will mainly concentrate on the atmospheric fragmentation analysis. The extent of the dust trail up to the heights of 70 km demonstrates that significant mass loss occurred from the early parts of the luminous trajectory. Nevertheless, no flare was seen on the early portion of the lightcurve, suggesting that no sudden disruption occurred here and the mass was probably being lost from the asteroid surface. The first break-up occurred at the height of about 47 km. The large scale disruption, documented both by the lightcurve and sonic booms, occurred between the heights of 39--30 km. The fragmentation then ceased temporarily, but a number of surviving meter-sized boulders fragmented extensively again below 26 km. We will present a fragmentation model fitting both the observed lightcurve and deceleration. At lower heights, the deceleration of several individual fragments could be measured. The transverse speed of the major fragment was 400 m/s, much larger than expected, but of the same order of magnitude as observed in other cases including a sample of tiny meteoroids [4]. The unique aspect of Chelyabinsk was the formation of an extended dust trail

  11. Wind-influenced projectile motion

    NASA Astrophysics Data System (ADS)

    Bernardo, Reginald Christian; Perico Esguerra, Jose; Day Vallejos, Jazmine; Jerard Canda, Jeff

    2015-03-01

    We solved the wind-influenced projectile motion problem with the same initial and final heights and obtained exact analytical expressions for the shape of the trajectory, range, maximum height, time of flight, time of ascent, and time of descent with the help of the Lambert W function. It turns out that the range and maximum horizontal displacement are not always equal. When launched at a critical angle, the projectile will return to its starting position. It turns out that a launch angle of 90° maximizes the time of flight, time of ascent, time of descent, and maximum height and that the launch angle corresponding to maximum range can be obtained by solving a transcendental equation. Finally, we expressed in a parametric equation the locus of points corresponding to maximum heights for projectiles launched from the ground with the same initial speed in all directions. We used the results to estimate how much a moderate wind can modify a golf ball’s range and suggested other possible applications.

  12. Ablative shielding for hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A. (Inventor)

    1993-01-01

    A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.

  13. Craters in aluminum 1100 targets using glass projectiles at 1-7 km/s

    NASA Technical Reports Server (NTRS)

    Bernhard, R. P.; See, T. H.; Hoerz, F.; Cintala, M. J.

    1994-01-01

    We report on impact experiments using soda-lime glass spheres of 3.2 mm diameter and aluminum targets (1100 series). The purpose is to assist in the interpretation of LDEF instruments and in the development of future cosmic-dust collectors in low-Earth orbit. Because such instruments demand understanding of both the cratering and penetration process, we typically employ targets with thicknesses that range from massive, infinite half-space targets, to ultrathin films. This report addresses a subset of cratering experiments that were conducted to fine-tune our understanding of crater morphology as a function of impact velocity. Also, little empirical insight exists about the physical distribution and shock-metamorphism of the impactor residues as a function of encounter speed, despite their recognized significance in the analysis of space-exposed surfaces. Soda-lime glass spheres were chosen as a reasonable analog to extraterrestrial silicates, and aluminum 1100 was chosen for targets, which among the common Al-alloys, best represents the physical properties of high-purity aluminum. These materials complement existing impact studies that typically employed metallic impactors and less ductile Al-alloys. We have completed dimensional analyses of the resulting craters and are in the process of investigating the detailed distribution of the unmelted and melted impactor residues via SEM methods, as well as potential compositional modifications of the projectile melts via electron microprobe.

  14. Sequential injection gas guns for accelerating projectiles

    DOEpatents

    Lacy, Jeffrey M.; Chu, Henry S.; Novascone, Stephen R.

    2011-11-15

    Gas guns and methods for accelerating projectiles through such gas guns are described. More particularly, gas guns having a first injection port located proximate a breech end of a barrel and a second injection port located longitudinally between the first injection port and a muzzle end of the barrel are described. Additionally, modular gas guns that include a plurality of modules are described, wherein each module may include a barrel segment having one or more longitudinally spaced injection ports. Also, methods of accelerating a projectile through a gas gun, such as injecting a first pressurized gas into a barrel through a first injection port to accelerate the projectile and propel the projectile down the barrel past a second injection port and injecting a second pressurized gas into the barrel through the second injection port after passage of the projectile and to further accelerate the projectile are described.

  15. Projectile-generating explosive access tool

    DOEpatents

    Jakaboski, Juan-Carlos; Todd, Steven N.

    2011-10-18

    An explosive device that can generate a projectile from the opposite side of a wall from the side where the explosive device is detonated. The projectile can be generated without breaching the wall of the structure or container. The device can optionally open an aperture in a solid wall of a structure or a container and form a high-kinetic-energy projectile from the portion of the wall removed to create the aperture.

  16. Stopping power: Effect of the projectile deceleration

    SciTech Connect

    Kompaneets, Roman Ivlev, Alexei V.; Morfill, Gregor E.

    2014-11-15

    The stopping force is the force exerted on the projectile by its wake. Since the wake does not instantly adjust to the projectile velocity, the stopping force should be affected by the projectile deceleration caused by the stopping force itself. We address this effect by deriving the corresponding correction to the stopping force in the cold plasma approximation. By using the derived expression, we estimate that if the projectile is an ion passing through an electron-proton plasma, the correction is small when the stopping force is due to the plasma electrons, but can be significant when the stopping force is due to the protons.

  17. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2002-10-12

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant investigated for similar concepts in the past. This document reports on the progress made in the program during the past quarter. It reports on projectile development and the development of the electric launch system design.

  18. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2002-01-09

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant considered for similar concepts in the past. This document reports on the progress made in the program during the past quarter. It reports on projectile development experiments and the development of the electric launch system design.

  19. Projectile Motion Gets the Hose

    NASA Astrophysics Data System (ADS)

    Goff, John Eric; Liyanage, Chinthaka

    2011-10-01

    Students take a weekly quiz in our introductory physics course. During the week in which material focused on projectile motion, we not-so-subtly suggested what problem the students would see on the quiz. The quiz problem was an almost exact replica of a homework problem we worked through in the class preceding the quiz. The goal of the problem is to find the launch speed if the final horizontal and vertical positions and launch angle are given. Figure 1 shows a schematic of the trajectory.

  20. The impactor flux in the Pluto-Charon system

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Stern, S. Alan

    1994-01-01

    Current impact rates of comets on Pluto and Charon are estimated. It is shown that the dominant sources of impactors are comets from the Kuiper belt and the inner Oort cloud, each of whose perihelion distribution extends across Pluto's orbit. In contrast, long-period comets from the outer Oort cloud are a negligible source of impactors. The total predicted number of craters is not sufficient to saturate the surface areas of either Pluto of Charon over the age of the Solar System. However, heavy cratering may have occurred early in the Solar System's history during clearing of planetesimals from the outer planets' zone.

  1. Use of a New Portable Instrumented Impactor on the NASA Composite Crew Module Damage Tolerance Program

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; Polis, Daniel L.

    2014-01-01

    Damage tolerance performance is critical to composite structures because surface impacts at relatively low energies may result in a significant strength loss. For certification, damage tolerance criteria require aerospace vehicles to meet design loads while containing damage at critical locations. Data from standard small coupon testing are difficult to apply to larger more complex structures. Due to the complexity of predicting both the impact damage and the residual properties, damage tolerance is demonstrated primarily by testing. A portable, spring-propelled, impact device was developed which allows the impact damage response to be investigated on large specimens, full-scale components, or entire vehicles. During impact, both the force history and projectile velocity are captured. The device was successfully used to demonstrate the damage tolerance performance of the NASA Composite Crew Module. The impactor was used to impact 18 different design features at impact energies up to 35 J. Detailed examples of these results are presented, showing impact force histories, damage inspection results, and response to loading.

  2. Aerodynamic flail for a spinning projectile

    DOEpatents

    Cole, James K.

    1990-01-01

    A flail is provided which reduces the spin of a projectile in a recovery system which includes a parachute, a cable connected to the parachute, a swivel, and means for connecting the swivel to the projectile. The flail includes a plurality of flexible filaments and a rotor for attaching the filaments to the front end of the projectile. The rotor is located radially with respect to the spinning axis of the projectile. In one embodiment, the projectile includes a first nose cone section housing a deployable spin damping assembly; a second nose cone section, housing a deployable parachute assembly; a shell section, supporting the first and second nose cone sections during flight of the projectile; a mechanism for releasing the first nose cone section from the second cone section; and a mechanism for releasing the second nose cone section from the shell section. In operation of this embodiment, the deployable spin damping assembly deploys during flight of the projectile when the mechanism for releasing the first nose cone section from the second nose cone section are actuated. Then, upon actuation of the mechanism for releasing the second nose cone section from the shell section, two things happen: the spin damping assembly separates from the projectile; and the deployable parachute assembly is deployed.

  3. Aerodynamic flail for a spinning projectile

    DOEpatents

    Cole, James K.

    1990-05-01

    A flail is provided which reduces the spin of a projectile in a recovery system which includes a parachute, a cable connected to the parachute, a swivel, and means for connecting the swivel to the projectile. The flail includes a plurality of flexible filaments and a rotor for attaching the filaments to the front end of the projectile. The rotor is located radially with respect to the spinning axis of the projectile. In one embodiment, the projectile includes a first nose cone section housing a deployable spin damping assembly; a second nose cone section, housing a deployable parachute assembly; a shell section, supporting the first and second nose cone sections during flight of the projectile; a mechanism for releasing the first nose cone section from the second cone section; and a mechanism for releasing the second nose cone section from the shell section. In operation of this embodiment, the deployable spin damping assembly deploys during flight of the projectile when the mechanism for releasing the first nose cone section from the second nose cone section are actuated. Then, upon actuation of the mechanism for releasing the second nose cone section from the shell section, two things happen: the spin damping assembly separates from the projectile; and the deployable parachute assembly is deployed.

  4. Air sampling of mold spores by slit impactors: yield comparison.

    PubMed

    Pityn, Peter J; Anderson, James

    2013-01-01

    The performance of simple slit impactors for air sampling of mold contamination was compared under field conditions. Samples were collected side-by-side, outdoors in quadruplicates with Burkhard (ambient sampler) and Allergenco MK3 spore traps and with two identical Allergenco slit cassettes operated at diverse flow rates of 5 and 15 L/min, respectively. The number and types of mold spores in each sample were quantified by microscopy. Results showed all four single-stage slit impactors produced similar spore yields. Moreover, paired slit cassettes produced similar outcomes despite a three-fold difference in their sampling rate. No measurable difference in the amount or mix of mold spores per m(3)of air was detected. The implications for assessment of human exposures and interpretation of indoor/outdoor fungal burden are discussed. These findings demonstrate that slit cassettes capture most small spores, effectively and without bias, when operated at a range of flow rates including the lower flow rates used for personal sampling. Our findings indicate sampling data for mold spores correlate for different single stage impactor collection methodologies and that data quality is not deteriorated by operating conditions deviating from manufacturers' norms allowing such sampling results to be used for scientific, legal, investigative, or property insurance purposes. The same conclusion may not be applied to other particle sampling instruments and mulit-stage impactors used for ambient particulate sampling, which represent an entirely different scenario. This knowledge may help facilitate comparison between scientific studies where methodological differences exist.

  5. Particle impactor assembly for size selective high volume air sampler

    DOEpatents

    Langer, Gerhard

    1988-08-16

    Air containing entrained particulate matter is directed through a plurality of parallel, narrow, vertically oriented impactor slots of an inlet element toward an adjacently located, relatively large, dust impaction surface preferably covered with an adhesive material. The air flow turns over the impaction surface, leaving behind the relatively larger particles according to the human thoracic separation system and passes through two elongate exhaust apertures defining the outer bounds of the impaction collection surface to pass through divergent passages which slow down and distribute the air flow, with entrained smaller particles, over a fine filter element that separates the fine particles from the air. The elongate exhaust apertures defining the impaction collection surface are spaced apart by a distance greater than the lengths of elongate impactor slots in the inlet element and are oriented to be normal thereto. By appropriate selection of dimensions and the number of impactor slots air flow through the inlet element is provided a nonuniform velocity distribution with the lower velocities being obtained near the center of the impactor slots, in order to separate out particles larger than a certain predetermined size on the impaction collection surface. The impaction collection surface, even in a moderately sized apparatus, is thus relatively large and permits the prolonged sampling of air for periods extending to four weeks.

  6. 16 CFR Figure 5 to Subpart A of... - Impactor

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5...

  7. 16 CFR Figure 5 to Subpart A of... - Impactor

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5...

  8. 16 CFR Figure 5 to Subpart A of... - Impactor

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5...

  9. 16 CFR Figure 5 to Subpart A of... - Impactor

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5...

  10. 16 CFR Figure 5 to Subpart A of... - Impactor

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5...

  11. Experimental Characterization of Microfabricated VirtualImpactor Efficiency

    EPA Science Inventory

    The Air-Microfluidics Group is developing a microelectromechanical systems-based direct reading particulate matter (PM) mass sensor. The sensor consists of two main components: a microfabricated virtual impactor (VI) and a PM mass sensor. The VI leverages particle inertia to sepa...

  12. Virtual Impactor for Sub-micron Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Bolshakov, A. A.; Strawa, A. W.; Hallar, A. G.

    2005-12-01

    The objective of a virtual impactor is to separate out the larger particles in a flow from the smaller particles in such a way that both sizes of particles are available for sampling. A jet of particle-laden air is accelerated toward a collection probe so that a small gap exists between the acceleration nozzle and the probe. A vacuum is applied to deflect a major portion of the airstream away form the collection probe. Particles larger than a certain size have sufficient momentum so that they cross the deflected streamlines and enter the collection probe, whereas smaller particles follow the deflected streamlines. The result is that the collection probe will contain a higher concentration of larger particles than is in the initial airstream. Typically, virtual impactors are high-flow devices used to separate out particles greater than several microns in diameter. We have developed a special virtual impactor to concentrate aerosol particles of diameters between 0.5 to 1 micron for the purpose of calibrating the optical cavity ring-down instrument [1]. No similar virtual impactors are commercially available. In our design, we have exploited considerations described earlier [2-4]. Performance of our virtual impactor was evaluated in an experimental set-up using TSI 3076 nebulizer and TSI 3936 scanning mobility particle size spectrometer. Under experimental conditions optimized for the best performance of the virtual impactor, we were able to concentrate the 700-nm polystyrene particles no less than 15-fold. However, under experimental conditions optimized for calibrating our cavity ring-down instrument, a concentration factor attainable was from 4 to 5. During calibration experiments, maximum realized particle number densities were 190, 300 and 1600 cm-3 for the 900-nm, 700-nm and 500-nm spheres, respectively. This paper discusses the design of the impactor and laboratory studies verifying its performance. References: 1. A.W. Strawa, R. Castaneda, T. Owano, D.S. Baer

  13. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Unknown

    2001-10-12

    The hypothesis to be tested is that the addition of steel or other synthetic fiber and/or high strength, low cost aggregate to strong grouts or concrete will result in a projectile of sufficient strength to produce cracking and spall enough to make its use cost effective for mining. Based on experiments conducted to date, no conclusions can yet be reached. Results of the experiments conducted suggest that reinforcement of a concrete projectile can yield performance that portends cost effective projectile based excavation. It is recognized that the projectile is but one component of the matrix. The electric launch system to be developed in the next phase of the program is the other factor that weighs heavily in the cost effectiveness equation. At this point, however, emerging low cost options for the projectile are very promising.

  14. Three-phase hypervelocity projectile launcher

    DOEpatents

    Fugelso, L. Erik; Langner, Gerald C.; Burns, Kerry L.; Albright, James N.

    1994-01-01

    A hypervelocity projectile launcher for use in perforating borehole casings provides improved penetration into the surrounding rock structure. The launcher includes a first cylinder of explosive material that defines an axial air-filled cavity, a second cylinder of explosive material defining an axial frustum-shaped cavity abutting and axially aligned with the first cylinder. A pliant washer is located between and axially aligned with the first and second cylinders. The frustum shaped cavity is lined with a metal liner effective to form a projectile when the first and second cylinders are detonated. The washer forms a unique intermediate projectile in advance of the liner projectile and enables the liner projectile to further penetrate into and fracture the adjacent rock structure.

  15. INVERTING CASCADE IMPACTOR DATA FOR SIZE-RESOLVED CHARACTERIZATION OF FINE PARTICULATE SOURCE EMISSIONS

    EPA Science Inventory

    Cascade impactors are particularly useful in determining the mass size distributions of particulate and individual chemical species. The impactor raw data must be inverted to reconstruct a continuous particle size distribution. An inversion method using a lognormal function for p...

  16. Safety assessment characteristics of pedestrian legform impactors in vehicle-front impact tests.

    PubMed

    Matsui, Yasuhiro

    2014-12-01

    This study investigated the characteristics of safety assessment results of front-area vehicle impact tests carried out using the Transport Research Laboratory (TRL) legform impactor and a flexible legform impactor (FLEX legform impactor). Different types of vehicles (sedan, sport utility vehicle, high-roof K-car, and light cargo van) were examined. The impact locations in the study were the center of the bumper and an extremely stiff structure of the bumper (i.e., in front of the side member) of each tested vehicle. The measured injury criteria were normalized by injury assessment reference values of each legform impactor. The test results for center and side-member impacts indicated that there were no significant differences in ligament injury assessments derived from the normalized knee ligament injury measures between the TRL legform impactor and the FLEX legform impactor. Evaluations made using the TRL legform impactor and the FLEX legform impactor are thus similar in the vehicle safety investigation for knee ligament injury. Vehicle-center impact test results revealed that the tibia fracture assessments derived from the normalized tibia fracture measures did not significantly differ between the TRL legform impactor and the FLEX legform impactor. However, for an impact against an extremely stiff structure, there was a difference in the tibia fracture assessment between the FLEX legform impactor and the TRL legform impactor owing to their different sensor types.

  17. Re-accretion Efficiencies in Small Impactor - Large Target Collisions

    NASA Astrophysics Data System (ADS)

    Jankowski, Tim; Wurm, G.; Jens, T.

    2013-10-01

    During the formation process of planets, small dust particles grow to km-sized planetesimals via collisions. While the collision partners are equally sized in early phases, fragmentation, catastrophic destruction and other recycling processes can lead to collisions between partners with various size ranges. The gas in protoplanetary disks exerts size- and mass-dependent drag forces on the dust particles and bodies present which is why the relative velocities between the small particles and larger bodies increase. A field of investigation are the small-impactor large-target collisions where (partial) erosion can occur and small ejected dust particles can be produced. These ejecta can couple to the gas quite rapidly and can then be recaptured by the target and stick to it in secondary collisions. We use a Monte-Carlo code to calculate re-accretion efficiencies under certain conditions i.e. in free molecular flow regime (stream lines end on target body; impactors are completely coupled to the gas). Using experimental data we developed a model for the amount, masses, directions, and velocities of the ejecta depending on the impactor mass and velocity and the position of impact. The amount of re-accreted ejecta as well as the total re-accreted mass can be determined by using the solution of the equation of motion for particles in gaseous environments. Both - the amount dependent efficiency as well as the mass dependent efficiency - are highly dependent on the seven free parameters (impact velocity, impactor size and density, target size and density, gas pressure and temperature) but generally benefit from high gas velocities and a large size difference between target and impactor. Our final intention is to provide an analytical expression for the re-accretion efficiencies in respect to the free parameters and to use this in different disk models for sweeping the free parameters dependent on the distance to the central star. One major advantage of our code is the

  18. Magnetic detector for projectiles in tubes

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.; Knowlen, C.; Murakami, D.; Stonich, I.

    1990-01-01

    A new wall-mounted, magnetic detector is presented for measuring projectile passage times in tubes. The detector has the advantages of simplicity over laser and microwave techniques and has other advantages over the electrical contact wire technique. Representative data are presented. The detector is shown to be very insensitive to strong pressure waves and combustion, but able to detect the passage of the projectile (carrying one or two magnets) clearly. Two modes of operation of the detector are described and the use of these detectors to measure projectile velocities, accelerations, and spin rates is discussed.

  19. Projectile dynamics at low barrel pressures

    NASA Astrophysics Data System (ADS)

    Chankaev, S. K.; Yakovlev, V. Ya.

    2007-11-01

    A mathematical model for a projectile shot at low pressures in the space behind the projectile space is developed. The pressure rise is limited because of the nonsimultaneity of propellant ignition and combustion and the discharge of the propellant combustion products through the gap between the projectile and the walls of the gun barrel. The kinetic characteristics of flame propagation over the propellant particles are determined. A comparison of calculation and experimental data is performed. The calculation results are used in designing 2A85 self-propelled launchers and upgrading 2A30 self-propelled launchers.

  20. A Study of the Trajectories of Projectiles.

    ERIC Educational Resources Information Center

    Grant, A. Ruari

    1990-01-01

    Described is a procedure for studying the trajectories of projectiles using ball bearings and aluminum foil. Trajectories were measured with and without the effects of air resistance. Multiflash photography was used to determine the flight paths of all objects. (KR)

  1. Hypervelocity High Speed Projectile Imagery and Video

    NASA Technical Reports Server (NTRS)

    Henderson, Donald J.

    2009-01-01

    This DVD contains video showing the results of hypervelocity impact. One is showing a projectile impact on a Kevlar wrapped Aluminum bottle containing 3000 psi gaseous oxygen. One video show animations of a two stage light gas gun.

  2. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2003-06-06

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant considered for similar concepts in the past. This document reports on the program findings through the first two phases. It presents projectile design and experiment data and the preliminary design for electric launch system. Advanced Power Technologies, Inc., now BAE SYSTEMS Advanced Technologies, Inc., was forced to withdraw from the program with the loss of one of our principal mining partners, however, the experiments conducted suggest that the approach is feasible and can be made cost effective.

  3. Projectile oscillations in augmented rail guns

    SciTech Connect

    Hodgdon, M.L.; Fowler, C.M.; Homan, C.G.

    1986-01-01

    The projectile in an inductive store-powered rail gun, augmented by an external magnetic field, will oscillate under certain conditions. This behavior is easily understood when there is no resistance in the circuit comprising the storage coil, rails and armature. In this case, the flux in the complete circuit is conserved. However, as the projectile moves down the rails, more flux from the augmenting field is picked up. This must be accompanied by a decrease in current in the system to conserve the total flux. At a certain distance down the rails, the current must reverse to conserve the flux, and thus the force on the projectile reverses. This mechanism leads to oscillation of the projectile. An analytic solution is given for the case in which the resistance is zero.

  4. Electromagnetic theta gun and tubular projectiles

    SciTech Connect

    Burgess, T.J.; Cnare, E.C.; Oberkampf, W.L.; Beard, S.G.; Cowan, M.

    1980-12-01

    Unlike the better known rail gun, the theta gun applies the propelling force along the length of its projectile. This is shown to allow much greater acceleration of high fineness ratio projectiles for a given barrel pressure, allowing much shorter barrels for military applications. A computer code which simulates performance of the theta gun is described and experimental results from a few simple, low energy experiments show close agreement with code predictions. Trajectories and aerodynamic heating for three candidate military projectiles are calculated for vertical and horizontal atmospheric launches where initial velocity is as high as 3 km/s. The calculations indicate that in some cases a thin layer of heatshield (ablator) will be required to control projectile heating.

  5. Target Neutron Skin Effect on Projectile Fragmentation

    NASA Astrophysics Data System (ADS)

    Laforest, R.; Ramakrishnan, E.; Rowland, D. J.; Winchester, E.; Delafield, R.; Guzman, S. J.; Yennello, S.

    1998-04-01

    Several experimental observables have concluded that projectile fragmentation occurs as a two step process, excitation followed by the sequential decay of the quasi-projectile. However, recent measurements [1] have shown that neutron rich fragments are emitted with smaller velocities than what is expected from the decay of the projectile. A direct breakup mechanism for projectile fragmentation was suggested to explain the data. This direct breakup component depends on the number of neutrons at the zone of contact between the target and the projectile. Experimental data from the reactions of ^28Si on ^112,124Sn targets at 50A MeV were used to study the effect of the neutron skin of the target on projectile fragmentation and on energy dissipation in peripheral collisions. The FAUST forward array was used to detect fragments in the angular range between 1.6 to 33.6 degrees. It is composed of 68 high resolution Si-Csi(Tl) telescopes that allows for isotope identification. It is seen that the neutron rich target yields more neutron rich fragments and a lower fragment multiplicity. This confirms the importance of the direct breakup component. Proton kinetic energy spectra were also different for the two targets. This experimental information can shed some light on the isospin dependence of the equation of state. [1] R. Charity et al., Phys. Rev. C52 (1995) 1.

  6. Multi-shock assembly for protecting a spacecraft surface from hypervelocity impactors

    NASA Technical Reports Server (NTRS)

    Dvorak, Bruce D. (Inventor)

    2001-01-01

    A hypervelocity impact shield assembly for protecting a spacecraft surface from hypervelocity impactors. The shield assembly includes at least one sacrificial impactor disrupting/shocking layer of hypervelocity impactor disrupting/shocking material. A primary spacing element, including space-rated open cell foam material, is positioned between the at least one sacrificial impactor disrupting/shocking layer and a spacecraft surface. A cover member is arranged and disposed relative to the sacrificial impactor disrupting/shocking layer and the primary spacing element to maintain the integrity of the hypervelocity impact shield assembly. In the event of exposure to a hypervelocity impactor, the sacrificial impactor disrupting/shocking layer is perforated while shocking the impactor breaking it into fragments, and/or melting it, and/or vaporizing it, thus providing a dispersion in the form of an expanding debris cloud/plume which spreads the impact energy of the impactor over a volume formed by the primary spacing element between the sacrificial impactor disrupting/shocking layer and the spacecraft surface. This significantly reduces impact lethality at the spacecraft surface. The space-rated open cell foam material provides an extremely lightweight, low-cost, efficient means of spacing and supporting the at least one sacrificial impactor disrupting/shocking layer before, during, and after launch. In a preferred embodiment, the invention is in the form of a multi-shock assembly including a plurality of sacrificial impactor disrupting/shocking layers. In such instance, the hypervelocity impact shield assembly includes a plurality of secondary spacing elements. Each secondary spacing element is positioned adjacent an associated sacrificial impactor disrupting/shocking layer to form a multi-shock subassembly. Thus, a plurality of multi-shock subassemblies are provided which include alternating layers of sacrificial impactor disrupting/shocking layers and secondary spacing

  7. Projectile compositions and modal frequencies on the chemistry of micrometeoroids LDEF experiment

    NASA Technical Reports Server (NTRS)

    Bernhard, Ronald P.; See, Thomas H.; Hoerz, Friedrich

    1993-01-01

    The Chemistry of Micrometeoroids Experiment (LDEF instrument A0187-1) exposed witness plates of high-purity gold (greater than 99.99 percent Au) and commercial aluminum (greater than 99 percent Al) with the objective of analyzing the residues of cosmic-dust and orbital-debris particles associated with hypervelocity impact craters. The gold substrates were located approximately 8 deg off LDEF's trailing edge (Bay A03), while the aluminum surfaces resided in Bay A11, approximately 52 deg from LDEF's leading edge. SEM-EDX techniques were employed to analyze the residues associated with 199 impacts on the gold and 415 impacts on the aluminum surfaces. The residues that could be analyzed represent natural or man-made materials. The natural particles dominate at all particle sizes less than 5 micron. It is possible to subdivide both particle populations into subclasses. Chondritic compositions dominate the natural impactors (71 percent), followed by monomineralic, mafic-silicate compositions (26 percent), and by Fe-Ni rich sulfides (approximately 3 percent). Approximately 30 percent of all craters on the gold collectors were caused by man-made debris such as aluminum, paint flakes, and other disintegrated, structural and electronic components. Equations-of-state and associated calculations of shock stresses for typical LDEF impacts into the gold and aluminum substrates suggest that substantial vaporization may have occurred during many of the impacts and is the reason why approximately 50 percent of all craters did not contain sufficient residue to permit analysis by the SEM-EDX technique. After converting the crater diameters into projectile sizes using encounter speeds typical for the trailing-edge and forward-facing (Row 11) directions, and accounting for normalized exposure conditions of the CME collectors, we derived the absolute and relative fluxes of specific projectile classes. The natural impactors encounter all LDEF pointing directions with comparable, modal

  8. Orbital and Physical Characteristics of Meter-sized Earth Impactors

    NASA Astrophysics Data System (ADS)

    Brown, Peter G.; Wiegert, Paul; Clark, David; Tagliaferri, Edward

    2015-11-01

    We have analysed the orbits and ablation characteristics in the atmosphere of more than 60 earth-impacting meteoroids of one meter in diameter or larger. Using heights at peak luminosity as a proxy for strength, we find that there is roughly an order of magnitude spread in the apparent strength of the population of meter-sized impactors at the Earth. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. We find ~10-15% of our objects have a probable cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, show evidence for the expected weaker than average structure compared to asteroidal bodies. Almost all impactors show peak brightness between 20-40 km altitude. Several events have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though all were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several NEOs in our population with the Taurid meteoroid complex. No other major meteoroid streams show linkages with the pre-atmospheric orbits of our meter-class impactors. Our events cover almost four orders of magnitude in mass, but no trend in height of peak brightness is evident, suggesting no strong trend in strength with size for small NEOs, a finding consistent with the results of Popova et al (2011).

  9. The origin of planetary impactors in the inner solar system.

    PubMed

    Strom, Robert G; Malhotra, Renu; Ito, Takashi; Yoshida, Fumi; Kring, David A

    2005-09-16

    Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended approximately 3.8 billion years ago were made by asteroids that were dynamically ejected from the main asteroid belt, possibly due to the orbital migration of the giant planets. The impactors of the past approximately 3.8 billion years have a size distribution quite different from that of the main belt asteroids but very similar to that of near-Earth asteroids. PMID:16166515

  10. Craters on Pluto and Charon: Characteristics and Impactor Population

    NASA Astrophysics Data System (ADS)

    Singer, Kelsi N.; Schenk, Paul M.; Robbins, Stuart J.; Bray, Veronica J.; McKinnon, William B.; Moore, Jeffrey M.; Spencer, John R.; Stern, S. A.; Grundy, W. M.; Howett, Carly J. A.; Dalle Ore, Cristina M.; Beyer, Ross; Parker, Alex H.; Porter, Simon B.; Zangari, Amanda M.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly

    2015-11-01

    Although both Pluto and Charon have a surprising number of young-looking surfaces, there are still plenty of craters for impact-phenomenon enthusiasts. We will present size, morphology, ejecta, and albedo pattern statistics, in addition to correlations with color/composition where possible. We use images and topography from the Long Range Reconnaissance Imager (LORRI; Cheng et al., 2008, SSR 140, 189-215) and data from the Ralph (Reuter et al., 2008, SSR 140, 129-154) color/composition instruments.Impactor sizes will be estimated from relevant scaling laws for cold water ice (see details in Singer and Stern, 2015, ApJL 808, L50). For Pluto, an image strip at 125 m px-1 includes some cratered terrains, and much of the encounter hemisphere (the anti-Charon hemisphere) will be covered at ~400 m px-1. The ~smallest craters observable at these pixel scales (using a 5 pixel limit) would be ~0.63 km, and ~2 km in diameter, respectively, with impactor diameters estimated at ~50 m, and ~200 m. However, it is likely that degradation processes may obscure small craters, thus this lower observation limit will depend on terrain type. Additionally, lighting and observation geometries vary across the disk, which may make crater detection difficult in some areas. All of the illuminated portions of Pluto (during its 6.4 day rotation period) were imaged at ~20 km px-1 or better during the encounter. The highest resolution images of Pluto (at ~80 m px-1) occur in a narrow strip and are not scheduled for downlink before the DPS.The highest resolution Charon coverage (a strip at ~160 m px-1), a broader swath at 400 m px-1, and the entire encounter hemisphere (the sub-Pluto hemisphere) at ~890 m px-1 may yield craters as small as 0.8, 2, and 4.5 km in diameter, respectively. The inferred impactor sizes for these craters would be ~50 m, 160 m, and 440 m.Although the dataset is limited, we will discuss what constraints can be put on the impactor population. This work was supported by the

  11. Additional Crime Scenes for Projectile Motion Unit

    NASA Astrophysics Data System (ADS)

    Fullerton, Dan; Bonner, David

    2011-12-01

    Building students' ability to transfer physics fundamentals to real-world applications establishes a deeper understanding of underlying concepts while enhancing student interest. Forensic science offers a great opportunity for students to apply physics to highly engaging, real-world contexts. Integrating these opportunities into inquiry-based problem solving in a team environment provides a terrific backdrop for fostering communication, analysis, and critical thinking skills. One such activity, inspired jointly by the museum exhibit "CSI: The Experience"2 and David Bonner's TPT article "Increasing Student Engagement and Enthusiasm: A Projectile Motion Crime Scene,"3 provides students with three different crime scenes, each requiring an analysis of projectile motion. In this lesson students socially engage in higher-order analysis of two-dimensional projectile motion problems by collecting information from 3-D scale models and collaborating with one another on its interpretation, in addition to diagramming and mathematical analysis typical to problem solving in physics.

  12. Characterization of a Regenerable Impactor Filter for Spacecraft Cabin Applications

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.; Vijayakumar, R.

    2015-01-01

    Regenerable filters will play an important role in human exploration beyond low-Earth orbit. Life Support Systems aboard crewed spacecrafts will have to operate reliably and with little maintenance over periods of more than a year, even multiple years. Air filters are a key component of spacecraft life support systems, but they often require frequent routine maintenance. Bacterial filters aboard the International Space Station require almost weekly cleaning of the pre-filter screen to remove large lint debris captured in the microgravity environment. The source of the airborne matter which is collected on the filter screen is typically from clothing fibers, biological matter (hair, skin, nails, etc.) and material wear. Clearly a need for low maintenance filters requiring little to no crew intervention will be vital to the success of the mission. An impactor filter is being developed and tested to address this need. This filter captures large particle matter through inertial separation and impaction methods on collection surfaces, which can be automatically cleaned after they become heavily loaded. The impactor filter can serve as a pre-filter to augment the life of higher efficiency filters that capture fine and ultrafine particles. A prototype of the filter is being tested at the Particulate Filtration Laboratory at NASA Glenn Research Center to determine performance characteristics, including particle cut size and overall efficiency. Model results are presented for the flow characteristics near the orifice plate through which the particle-laden flow is accelerated as well as around the collection bands.

  13. Calibration and evaluation of a real-time cascade impactor

    SciTech Connect

    Fairchild, C.I.; Wheat, L.D.

    1984-04-01

    A 10-stage cascade impactor made by California Measurement Inc., can determine aerodynamic size distributions of dilute aerosols in a few minutes. Collection of impacted particles on greased, vibrating piezoelectric crystals produces changes in vibrational frequency proportional to the collected mass. Based on frequency changes and sampling time, a data reduction module calculates the mass collected on each stage. Calibration of the assembled impactor was performed with monodisperse polystyrene latex (PSL) and Eosin-Y (E-Y) aerosols for the lower stages (4-10), and PSL and pollen particles (ragweed and mulberry) for the upper stages (1-3). The stage experimental effective cutoff aerodynamic diameters (ECAD) were up to 22 percent different from theoretical ECADs with the exception of Stages 1 and 2 which were respectively 30 and 35 percent different from theoretical ECADs. The overall loss of particles > 3- and < 0.3-..mu..m was severe. Also, considerable scatter of particles was observed on the collection crystals of Stages 1 and 2. Although a majority of particles were in the impaction area, a large fraction was scattered over the outer portions of these crystals.

  14. Closed Loop Terminal Guidance Navigation for a Kinetic Impactor Spacecraft

    NASA Technical Reports Server (NTRS)

    Bhaskaran, Shyam; Kennedy, Brian

    2013-01-01

    A kinetic impactor spacecraft is a viable method to deflect an asteroid which poses a threat to the Earth. The technology to perform such a deflection has been demonstrated by the Deep Impact (DI) mission, which successfully collided with comet Tempel 1 in July 2005 using an onboard autonomous navigation system, called AutoNav, for the terminal phase of the mission. In this paper, we evaluate the ability of AutoNav to impact a wide range of scenarios that an deflection mission could encounter, varying parameters such as the approach velocity, phase angle, size of the asteroid, and the determination of spacecraft attitude. Using realistic Monte Carlo simulations, we tabulated the probability of success of the deflection as a function of these parameters, and the highest sensitivity to be due the spacecraft attitude determination mode. In addition, we also specifically analyzed the impact probability for a proposed mission which would send an impactor to the asteroid 1999RQ36. We conclude with some recommendations for future work.

  15. The cometary and asteroidal impactor flux at the earth

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.

    1988-01-01

    The cratering records on the Earth and the lunar maria provide upper limits on the total impactor flux at the Earth's orbit over the past 600 Myr and the past 3.3 Gyr, respectively. These limits can be compared with estimates of the expected cratering rate from observed comets and asteroids in Earth-crossing orbits, corrected for observational selection effects and incompleteness, and including expected temporal variations in the impactor flux. Both estimates can also be used to calculate the probability of large impacts which may result in biological extinction events on the Earth. The estimated cratering rate on the Earth for craters greater than 10 km-diameter, based on counted craters on dated surfaces is 2.2 + or - 1.1 x 10 to the minus 14th power km(-2) yr(-1) (Shoemaker et al., 1979). Using a revised mass distribution for cometary nuclei based on the results of the spacecraft flybys of Comet Halley in 1986, and other refinements in the estimate of the cometary flux in the terrestrial planets zone, it is now estimated that long-period comets account for 11 percent of the cratering on the Earth (scaled to the estimate above), and short-period comets account for 4 pct (Weissman, 1987). However, the greatest contribution is from large but infrequent, random cometary showers, accounting for 22 pct of the terrestrial cratering.

  16. Dynamic effects of interaction of composite projectiles with targets

    NASA Astrophysics Data System (ADS)

    Zakharov, V. M.

    2016-01-01

    The process of high-speed impact of projectiles against targets of finite thickness is experimentally investigated. Medium-hard steel plates are used as targets. The objective of this research is to carry out a comparative analysis of dynamic effects of interaction of various types of projectiles with targets, such as characteristics of destruction of the target, the state of the projectile behind the target, and particularities of the after-penetration stream of fragments after the target has been pierced. The projectiles are made of composites on the basis of tungsten carbide obtained by caking and the SHS-technology. To compare effectiveness of composite projectiles steel projectiles are used. Their effectiveness was estimated in terms of the ballistic limit. High density projectiles obtained by means of the SHS-technology are shown to produce results comparable in terms of the ballistic limit with high-strength projectiles that contain tungsten received by caking.

  17. Europa's small impactor flux and seismic detection predictions

    NASA Astrophysics Data System (ADS)

    Tsuji, Daisuke; Teanby, Nicholas A.

    2016-10-01

    Europa is an attractive target for future lander missions due to its dynamic surface and potentially habitable sub-surface environment. Seismology has the potential to provide powerful new constraints on the internal structure using natural sources such as faults or meteorite impacts. Here we predict how many meteorite impacts are likely to be detected using a single seismic station on Europa to inform future mission planning efforts. To this end, we derive: (1) the current small impactor flux on Europa from Jupiter impact rate observations and models; (2) a crater diameter versus impactor energy scaling relation for icy moons by merging previous experiments and simulations; and (3) scaling relations for seismic signal amplitudes as a function of distance from the impact site for a given crater size, based on analogue explosive data obtained on Earth's ice sheets. Finally, seismic amplitudes are compared to predicted noise levels and seismometer performance to determine detection rates. We predict detection of 0.002-20 small local impacts per year based on P-waves travelling directly through the ice crust. Larger regional and global-scale impact events, detected through mantle-refracted waves, are predicted to be extremely rare (10-8-1 detections per year), so are unlikely to be detected by a short duration mission. Estimated ranges include uncertainties from internal seismic attenuation, impactor flux, and seismic amplitude scaling. Internal attenuation is the most significant unknown and produces extreme uncertainties in the mantle-refracted P-wave amplitudes. Our nominal best-guess attenuation model predicts 0.002-5 local direct P detections and 6 × 10-6-0.2 mantle-refracted detections per year. Given that a plausible Europa landed mission will only last around 30 days, we conclude that impacts should not be relied upon for a seismic exploration of Europa. For future seismic exploration, faulting due to stresses in the rigid outer ice shell is likely to be a

  18. Speed, Acceleration, Chameleons and Cherry Pit Projectiles

    ERIC Educational Resources Information Center

    Planinsic, Gorazd; Likar, Andrej

    2012-01-01

    The paper describes the mechanics of cherry pit projectiles and ends with showing the similarity between cherry pit launching and chameleon tongue projecting mechanisms. The whole story is written as an investigation, following steps that resemble those typically taken by scientists and can therefore serve as an illustration of scientific…

  19. Interaction barriers for light, weakly bound projectiles

    SciTech Connect

    Kolata, J. J.; Aguilera, E. F.

    2009-02-15

    A parametrization of the interaction-barrier model of C. Y. Wong [Phys. Rev. Lett. 31, 766 (1973)] is given for light, weakly bound projectiles and also for the exotic 'halo' nuclei {sup 6}He and {sup 8}B. Comparisons are made with the original parametrization. The extremely anomalous behavior of the interaction radius and barrier curvature for halo nuclei is discussed.

  20. Launching a Projectile into Deep Space

    ERIC Educational Resources Information Center

    Maruszewski, Richard F., Jr.

    2004-01-01

    As part of the discussion about Newton's work in a history of mathematics course, one of the presentations calculated the amount of energy necessary to send a projectile into deep space. Afterwards, the students asked for a recalculation with two changes: First the launch under study consisted of a single stage, but the students desired to…

  1. Developing Impact Marking Projectiles Using Triboluminescent Materials

    NASA Astrophysics Data System (ADS)

    Hollerman, William; Fontenot, Ross; Broussard, Brady; Goedeke, Shawn; Guidry, Corey

    2011-06-01

    In 1888, Wiedemann and Schmidt defined triboluminescence as the emission of light produced by mechanical action. In 1999, Sage and Geddes patented a design for a sensor capable of discerning the locations of impacts. Their design involved embedding a sensor inside a material coated with a triboluminescent crystal. Using this idea, the authors have been investigating the triboluminescent properties of several materials (like ZnS:Mn) for their possible use as the active element in ballistic projectiles. These new and improved rounds would be very useful because triboluminescence would mark the landing point of the projectile. This light would be ``cold'' in the sense it was not generated as a result of burning gunpowder or similar pyrotechnics. This light emission would also have a relatively short duration compared to other new projectiles, which generate long-term phosphorescence when two chemicals are mixed at impact (chemiluminescence). This presentation will give a status report in our efforts to develop practical impact marking ballistic projectiles using a triboluminescent charge.

  2. Ballistics projectile image analysis for firearm identification.

    PubMed

    Li, Dongguang

    2006-10-01

    This paper is based upon the observation that, when a bullet is fired, it creates characteristic markings on the cartridge case and projectile. From these markings, over 30 different features can be distinguished, which, in combination, produce a "fingerprint" for a firearm. By analyzing features within such a set of firearm fingerprints, it will be possible to identify not only the type and model of a firearm, but also each and every individual weapon just as effectively as human fingerprint identification. A new analytic system based on the fast Fourier transform for identifying projectile specimens by the line-scan imaging technique is proposed in this paper. This paper develops optical, photonic, and mechanical techniques to map the topography of the surfaces of forensic projectiles for the purpose of identification. Experiments discussed in this paper are performed on images acquired from 16 various weapons. Experimental results show that the proposed system can be used for firearm identification efficiently and precisely through digitizing and analyzing the fired projectiles specimens.

  3. An Inexpensive Mechanical Model for Projectile Motion

    ERIC Educational Resources Information Center

    Kagan, David

    2011-01-01

    As experienced physicists, we see the beauty and simplicity of projectile motion. It is merely the superposition of uniform linear motion along the direction of the initial velocity vector and the downward motion due to the constant acceleration of gravity. We see the kinematic equations as just the mathematical machinery to perform the…

  4. Simultaneous Red - Blue Lidar and Airborne Impactor Measurements

    NASA Technical Reports Server (NTRS)

    McCormick, M. P.; Blifford, I. H.; Fuller, W. H.; Grams, G. W.

    1973-01-01

    Simultaneous two-color (0.6943 micrometers and 0.3472 micrometers) LIDAR measurements were made in the troposphere and lower stratosphere over Boulder, Colorado during March 1973. In addition, on the evening of March 26, airborne single-stage impactor measurements were made at four altitudes-- 10,500, 25,000, 33,000 and 43,000 feet MSL. These data were integrated at constant altitude for 15,45, 45, and 60 minutes respectively. The LIDAR data were taken with Langley's 48" LIDAR using a dichroic beamsplitter to separate the return at 0.6943 micrometers and 0.3472 micrometers. The analog waveforms for both colors were digitized simultaneously; one on an NCAR data acquisition system and the other on the 48" Langley data acquisition system. A discussion of the preliminary results from these measurements will be presented.

  5. Terrestrial impactors at geological boundary events - Comets or asteroids?

    NASA Technical Reports Server (NTRS)

    Weissman, P. R.

    1985-01-01

    In the present evaluation of evidence presented to date for a 26-28 million year periodicity in the extinction record and the age of large, well dated terrestrial impact craters, it is noted that no simple, one-to-one relationship emerges between major asteroid and/or comet impacts, siderophile anomalies, and biological extinction events. While impacts may indeed be the major extinction-triggering event in some or even most cases, either other major events, or secondary effects of the impacts, may be the actual extinction-causing mechanism. Long term obscuration of insolation, planetary cooling, or lethal atmospheric pollution may vary among extinctions, depending on the actual state of the planet and its biota during the geological period in question. The source of 28 million year-period asteroidal impactors, moreover, remains unknown and thereby casts doubt on the entire periodicity scenario.

  6. Flight Operations for the LCROSS Lunar Impactor Mission

    NASA Technical Reports Server (NTRS)

    Tompkins, Paul D.; Hunt, Rusty; D'Ortenzio, Matt D.; Strong, James; Galal, Ken; Bresina, John L.; Foreman, Darin; Barber, Robert; Shirley, Mark; Munger, James; Drucker, Eric

    2010-01-01

    The LCROSS (Lunar CRater Observation and Sensing Satellite) mission was conceived as a low-cost means of determining the nature of hydrogen concentrated at the polar regions of the moon. Co-manifested for launch with LRO (Lunar Reconnaissance Orbiter), LCROSS guided its spent Centaur upper stage into the Cabeus crater as a kinetic impactor, and observed the impact flash and resulting debris plume for signs of water and other compounds from a Shepherding Spacecraft. Led by NASA Ames Research Center, LCROSS flight operations spanned 112 days, from June 18 through October 9, 2009. This paper summarizes the experiences from the LCROSS flight, highlights the challenges faced during the mission, and examines the reasons for its ultimate success.

  7. Hypervelocity impact survivability experiments for carbonaceous impactors, part 2

    SciTech Connect

    Bunch, T.E.; Paque, J.M.; Becker, L.; Vedder, J.F.; Erlichman, J. ||

    1995-02-01

    Hypervelocity impact experiments were performed to further test the survivability of carbonaceous impactors and to determine potential products that may have been synthesized during impact. Diamonds were launched by the Ames two-stage light gas gun into Al plate at velocities of 2.75 and 3.1 km sec(exp -1). FESEM imagery confirms that diamond fragments survived in both experiments. Earlier experiments found that diamonds were destroyed on impact above 4.3 km sec(exp -1). Thus, the upper stability limit for diamond on impact into Al, as determined from our experimental conditions, is between 3.1 and 4.3 km sec(exp -1). Particles of the carbonaceous chondrite Nogoya were also launched into Al at a velocity of 6.2 km sec (exp -1). Laser desorption (L (exp 2) MS) analyses of the impactor residues indicate that the lowest and highest mass polycyclic aromatic hydrocarbons (PAH`s) were largely destroyed on impact; those of intermediate mass (202-220 amu) remained at the same level or increased in abundance. In addition, alkyl-substituted homologs of the most abundant pre-impacted PAH`s were synthesized during impact. These results suggest that an unknown fraction of some organic compounds can survive low to moderate impact velocities and that synthesized products can be expected to form up to velocities of, at least, 6.5 km sec(exp -1). The authors also present examples of craters formed by a unique microparticle accelerator that could launch micron-sized particles of almost any coherent material at velocities up to approximately 15 km sec(exp -1). Many of the experiments have a direct bearing on the interpretation of LDEF craters.

  8. The current impactor flux on Mars and its seasonal variation

    NASA Astrophysics Data System (ADS)

    JeongAhn, Youngmin; Malhotra, Renu

    2014-11-01

    We calculate the current impactor flux on Mars and its variation over the Martian year, using the available data on the orbital distribution of known Mars-crossing minor planets. To mitigate the problem of observational incompleteness, we adopt the orbital distribution of the nearly complete set of bright (absolute magnitude H<16) Mars-crossers as the intrinsic orbital distribution of the impactor population, and we use this distribution to generate a large number of clones to simulate the impact flux. We use the Öpik-Wetherill formulation for calculating collision probabilities. Our study pays careful attention to the effects of the non-uniform distribution of the perihelion longitudes (owed to planetary secular perturbations) and the non-uniform distribution of impact velocities. We find that these previously neglected non-uniformities have a significant effect on the mean annual impact flux as well as its seasonal variation. The impact flux peaks when Mars is at aphelion. The near-alignment of Mars' eccentricity vector with the mean direction of the eccentricity vector distribution of Mars-crossers causes the mean annual impact flux as well as the amplitude of the seasonal variation to be significantly lower than the estimate based on a uniform random distribution of perihelion longitudes of Mars-crossers. Extrapolation of our results to a de-biased population model of fainter (smaller) Mars-crossers provides theoretical predictions that can be tested with observational data of impacts that is becoming available from spacecraft currently in orbit about Mars.This research was supported by NSF grant #AST-1312498.

  9. Hypervelocity impact survivability experiments for carbonaceous impactors, part 2

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Paque, Julie M.; Becker, Luann; Vedder, James F.; Erlichman, Jozef

    1995-01-01

    Hypervelocity impact experiments were performed to further test the survivability of carbonaceous impactors and to determine potential products that may have been synthesized during impact. Diamonds were launched by the Ames two-stage light gas gun into Al plate at velocities of 2.75 and 3.1 km sec(exp -1). FESEM imagery confirms that diamond fragments survived in both experiments. Earlier experiments found that diamonds were destroyed on impact above 4.3 km sec(exp -1). Thus, the upper stability limit for diamond on impact into Al, as determined from our experimental conditions, is between 3.1 and 4.3 km sec(exp -1). Particles of the carbonaceous chondrite Nogoya were also launched into Al at a velocity of 6.2 km sec (exp -1). Laser desorption (L (exp 2) MS) analyses of the impactor residues indicate that the lowest and highest mass polycyclic aromatic hydrocarbons (PAH's) were largely destroyed on impact; those of intermediate mass (202-220 amu) remained at the same level or increased in abundance. In addition, alkyl-substituted homologs of the most abundant pre-impacted PAH's were synthesized during impact. These results suggest that an unknown fraction of some organic compounds can survive low to moderate impact velocities and that synthesized products can be expected to form up to velocities of, at least, 6.5 km sec(exp -1). We also present examples of craters formed by a unique microparticle accelerator that could launch micron-sized particles of almost any coherent material at velocities up to approximately 15 km sec(exp -1). Many of the experiments have a direct bearing on the interpretation of LDEF craters.

  10. Relationship of stage mensuration data to the performance of new and used cascade impactors.

    PubMed

    Roberts, Daryl L; Romay, Francisco J

    2005-01-01

    Cascade impaction is a standard test method for characterizing the quality of inhalable drug products. The sizes of the nozzles on each stage of the impactor are the critical dimensions for the performance of the impactor. Compendial reference methods call for periodic measurement of the size of the nozzles on each stage, a procedure known as stage mensuration. There is however currently no guidance on acceptable mensuration criteria. We aim to remedy this situation by providing a sound basis for understanding and using mensuration data, be it for acceptance criteria for new impactors or for the setting of mensuration tolerances for in-use impactors. We first show that multi-nozzle impactor stages behave as if all of the nozzles are equal in size to an effective diameter, , that is composed of the area-mean and areamedian diameters, W* and , calculated directly from the individual nozzle diameters for all nozzles on a given stage (equation 1): W= (W*)(2/3) x (W)(1/3) (1). Hence, the effective diameter provides an intuitive and technically sound basis for setting acceptance criteria for new and in-use impactors. We tabulate these criteria for the Mark II eight-stage Andersen cascade impactor and the Next Generation Pharmaceutical Impactor in a manner similar to the tables of critical impactor dimensions published in EP Supplement 5.1 and in USP 28. For two different impactors or for one impactor measured at two different times (e.g., at manufacture and in use), we find that the D50 values of a given stage are related to the effective diameters by D(50,2)/D(50,1)= (W(2)/W(1))(3/2) (2). Using the stage mensuration data for new, as-manufactured NGIs, we compare the D(50 )values of the first 125 as-manufactured NGIs with those of the archivally calibrated NGI. We further establish that the archivally calibrated NGI has D(50) values within 0.3% of an entirely perfect, hypothetical NGI with all nozzles equal to the nominal nozzle diameters. We also apply the equations to

  11. Calibration of the Andersen cascade impactor for the characterization of nasal products.

    PubMed

    Garmise, Robert J; Hickey, Anthony J

    2008-08-01

    Current cascade impactor protocols do not completely rule out nasal preparations entering the lower respiratory tract. A modified cascade impactor (MCI) was developed to characterize the particle size fraction capable of deposition in the lower respiratory tract. This is an important measure of the potential for delivery to a site which is not the route of administration, and which could lead to potential toxicity. Monodisperse aerosols were utilized to calibrate the Stage -2 and Stage -0 of an Andersen Mk II nonviable cascade impactor at 15 L per minute flow rate. While these sampling conditions are beyond the normal working range of impactor theory in practice the instrument was shown to discriminate the designated particle sizes sampled. This novel setup extended the upper limit of the range of particle sizes that the cascade impactor can characterize from 8.7 to 16.5 microm.

  12. Influence of Impactor Mass on the Damage Characteristics and Failure Strength of Laminated Composite Plates

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Kemmerly, Heather L.

    1998-01-01

    The results of an experimental study of the effect of impactor mass on the low-speed impact response of laminated flat composite plates is presented. Dropped weight impact response, damage characteristics, and residual strengths of quasi-isotropic flat plates are presented for a range of energy levels by systematically varying the mass of the impactor. Measured contact forces and damage areas are also presented. The results indicate that the contact force and damage area are nonlinear functions of the impactor mass and vary considerably over the entire range of energy levels considered. The different damage levels induced in a plate specimen when impacted at a given energy level with impactors of different masses significantly influence its compressive residual strength. The results provide clear and consistent trends in contact force, damage area, and compression-after-impact strength when the data are expressed as a function of the impactor momentum.

  13. Method of and apparatus for accelerating a projectile

    DOEpatents

    Goldstein, Yeshayahu S. A.; Tidman, Derek A.

    1986-01-01

    A projectile is accelerated along a confined path by supplying a pulsed high pressure, high velocity plasma jet to the rear of the projectile as the projectile traverses the path. The jet enters the confined path at a non-zero angle relative to the projectile path. The pulse is derived from a dielectric capillary tube having an interior wall from which plasma forming material is ablated in response to a discharge voltage. The projectile can be accelerated in response to the kinetic energy in the plasma jet or in response to a pressure increase of gases in the confined path resulting from the heat added to the gases by the plasma.

  14. Initiation of Gaseous Detonation by Conical Projectiles

    NASA Astrophysics Data System (ADS)

    Verreault, Jimmy

    Initiation and stabilization of detonation by hypersonic conical projectiles launched into combustible gas mixtures is investigated. This phenomenon must be understood for the design and optimization of specific hypersonic propulsion devices, such as the oblique detonation wave engine and the ram accelerator. The criteria for detonation initiation by a projectile is also related to fundamental aspects of detonation research, such as the requirement for direct initiation of a detonation by a blast wave. Experimental results of this problem also offer useful references for validation of numerical and theoretical modeling. Projectiles with cone half angles varying from 15° to 60° were launched into stoichiometric mixtures of hydrogen/oxygen with 70% argon dilution at initial pressures between 10 and 200 kPa. The projectiles were launched from a combustion-driven gas gun at velocities up to 2.2 km/s (corresponding to 133% of the Chapman Jouguet velocity). Pictures of the flowfields generated by the projectiles were taken via Schlieren photography. Five combustion regimes were observed about the projectile ranging from prompt and delayed oblique detonation wave formation, combustion instabilities, a wave splitting, and an inert shock wave. Two types of transition from the prompt oblique detonation wave regime to the inert shock regime were observed. The first (the delayed oblique detonation wave regime) showed an inert shock attached to the tip of the projectile followed by a sharp kink at the onset of an oblique detonation wave; this regime occurred by decreasing the cone angle at high mixture pressures. The second (the combustion instabilities regime) exhibited large density gradients due to combustion ignition and quenching phenomena; this regime occurred by decreasing the mixture pressure at large cone angles. A number of theoretical models were considered to predict critical conditions for the initiation of oblique detonations. The Lee-Vasiljev model agreed

  15. The influence of impactors on the chemical composition of Earth and Mars

    NASA Astrophysics Data System (ADS)

    Schmidt, G.

    2008-09-01

    Abstract A key issue for understanding the origin and the influence of impactors on the chemical composition of planets is the knowledge of the relative abundances of highly siderophile elements (HSE: Os, Ir, Ru, Pt, Rh, Pd) in the Earth's primitive upper mantle (PUM) and the continental upper crust (UCC). The past twelve years we have measured HSE in many mantle suites of the Earth by neutron activation. Estimates of Rh/Ir, Ru/Ir, Pd/Ir, and Pt/Os derived from PUM indicates modestly suprachondritic compositions [1]. The Os, Ir, Ru, Pt, and Pd pattern on PUM perfectly match the IVA iron meteorite Charlotte (Fig. 1) recently measured by Walker et al. [2]. The question raises if HSE in PUM are added to the accreting Earth by a late bombardment of iron meteorites or some unsampled inner solar system materials from formation regions closer to the sun (Mercury-Venus region), as it is supposed for enstatite chondrites and not sampled through meteorite collections? The HSE and Ni systematics of the UCC closely resembles IIIAB iron meteorites (many impact craters on Earth are produced by this type of iron meteorite projectiles, e.g. [3] and references therein), pallasites, and the evolved suite of Martian meteorites (Fig. 2), possibly representing the elemental pattern of the Martian crust [4]. Probably Martian crust and Earth crust preserves an imprint of similar materials. About 160 impacting asteroids (M-type objects?) with radii of 10 km would yield the total abundances of HSE and Ni in the UCC [5]. In fact the first meteorite of any type ever identified on another planet by NASA's Mars Exploration Rover Opportunity was an iron meteorite. [1] Schmidt G. 2004. Meteoritics & Planetary Science 39:1995-2007. [2] Walker R. J. et al. 2005. LPSC XXXVI, 1313. [3] Schmidt G. et al. 1997. Geochim.Cosmochim.Acta 61, 2977. [4] Jones J. H. et al. 2003. Chemical Geology 196, 21- 41. [5] Schmidt G. Meteoritics & Planetary Science, submitted. [6] Schmidt G. 2007. Lunar and Planet. Sci

  16. Geochemistry of impact glasses and target rocks from the Zhamanshin impact structure, Kazakhstan: Implications for mixing of target and impactor matter

    NASA Astrophysics Data System (ADS)

    Jonášová, Šárka; Ackerman, Lukáš; Žák, Karel; Skála, Roman; Ďurišová, Jana; Deutsch, Alexander; Magna, Tomáš

    2016-10-01

    Internal structure and element chemistry including contents of highly siderophile elements (HSE) and Os isotope ratios have been studied in target rocks and several groups of impact glasses of the Zhamanshin impact structure, Kazakhstan. These include larger irregularly-shaped fragments and blocks of impact glass (zhamanshinites), and three types of tektite-like splash-form glasses, part of fallback ejecta. These glassy objects typically are up to 30 mm large and are shaped as teardrops, irregularly bent and curved glass rods and fibers. They can be subdivided into acidic types (irghizites; typically 69-76 wt.% SiO2), basic splash-forms (typically 53-56 wt.% SiO2), and rarely occurring highly inhomogeneous composites with abundant mineral inclusions. A comparison with the target rocks shows that zhamanshinites and basic splash-forms usually have no detectable admixture of the projectile matter, indicated by major and trace elements as well as highly siderophile element contents, with the exception of one sample containing Fe-, Cr-, Ni- and Ti-enriched particles and elevated HSE contents. In contrast, irghizites exhibit clear admixture of the projectile matter, which was incorporated by complex processes accompanied by strong element fractionations. Microscopic investigations confirm that irghizites were formed mainly by coalescence of smaller molten glass droplets sized typically below 1 mm. Irghizites exhibit significant enrichments in Ni, Co and Cr, whose concentrations are locally elevated in the rims of the original small droplets. A portion of these elements and also part of Fe and Mn and other elements were derived from the impactor, most likely a Ni-rich carbonaceous chondrite. The contents of HSE are low and strongly fractionated, with moderate depletions of Pt and Pd and strong depletions of other HSE with respect to chondritic element ratios. Osmium shows the strongest depletion, likely related to the presence of oxygen in the post-impact atmosphere

  17. Apparatus and method for the acceleration of projectiles to hypervelocities

    DOEpatents

    Hertzberg, Abraham; Bruckner, Adam P.; Bogdanoff, David W.

    1990-01-01

    A projectile is initially accelerated to a supersonic velocity and then injected into a launch tube filled with a gaseous propellant. The projectile outer surface and launch tube inner surface form a ramjet having a diffuser, a combustion chamber and a nozzle. A catalytic coated flame holder projecting from the projectile ignites the gaseous propellant in the combustion chamber thereby accelerating the projectile in a subsonic combustion mode zone. The projectile then enters an overdriven detonation wave launch tube zone wherein further projectile acceleration is achieved by a formed, controlled overdriven detonation wave capable of igniting the gaseous propellant in the combustion chamber. Ultrahigh velocity projectile accelerations are achieved in a launch tube layered detonation zone having an inner sleeve filled with hydrogen gas. An explosive, which is disposed in the annular zone between the inner sleeve and the launch tube, explodes responsive to an impinging shock wave emanating from the diffuser of the accelerating projectile thereby forcing the inner sleeve inward and imparting an acceleration to the projectile. For applications wherein solid or liquid high explosives are employed, the explosion thereof forces the inner sleeve inward, forming a throat behind the projectile. This throat chokes flow behind, thereby imparting an acceleration to the projectile.

  18. Aerodynamic characteristics of nebulized terbutaline sulphate using the Andersen Cascade Impactor compared to the Next Generation Impactor.

    PubMed

    Abdelrahim, Mohamed E

    2011-04-01

    Characterization of the aerosol emitted from nebulizers is determined using the Next Generation Impactor (NGI). The Andersen Cascade Impactor (ACI) was previously used but the limitation of high flow rate used decreased its uses. We have investigated the use of ACI with different operational conditions compared to the NGI methodology. NGI was operated at a flow rate of 15 L min⁻¹ after cooling at 5°C for 90 min. ACI was operated using flow rates 15 and 28.3 L min⁻¹ at room (ROOM) temperature and after cooling at 5 °C for 60 min (COLD). ACI was also operated using a flow rate 15 L min⁻¹ through the nebulizer T-piece with a flow rate 28.3 L min⁻¹ through ACI (15 Mix) using the mixing valve at ROOM and COLD. Two nebulizer systems, the Sidestream (SIDE) and the Aeroneb Pro (AERO) were used to nebulize terbutaline sulphate respiratory solution. Overall there was a highly significant difference (P < 0.001) between different ACI operating conditions for FPF and MMAD of both nebulizer systems. The ACI at higher flow rate increased the evaporation effect whilst cooling minimized evaporation of both nebulizer systems. Hence cooling and using slow flow rate minimizes evaporation effects with ACI. The ACI 15COLD results were similar to that of NGI. That supports the use of ACI at inhalation flow rate 15 L min⁻¹ without fear of domination of gravity on ACI stages. PMID:20100034

  19. Shallow-angle water entry of ballistic projectiles

    NASA Astrophysics Data System (ADS)

    Truscott, Tadd T.; Gomez, Jason T.; Beal, David N.; Techet, Alexandra H.

    2008-11-01

    The water-entry of ballistic projectiles is investigated using high-speed digital imaging. Projectiles enter the water at shallow angles to the free surface, 5^o-15^o, without ricochet at Mach numbers between 0.3 and 2.0. Projectile dynamics, critical entry angle, and cavity growth are discussed. Geometric modifications to a projectile allow it to travel large distances underwater assuming a sufficiently large air-cavity is formed after impact, which dramatically decreases drag on the projectile. Results show that successful water-entry occurs for projectiles with modified tip geometries at Mach numbers ranging from 0.3 to 2; these projectile modifications include tip geometry and material properties. A theoretical cavity model compares well with the experimental data and will be discussed for a range of experimental conditions.

  20. Slit-Drum Camera For Projectile Studies

    NASA Astrophysics Data System (ADS)

    Liangyi, Chen; Shaoxiang, Zhou; Guanhua, Cha; Yuxi, Hu

    1983-03-01

    The' model XF-70 slit-drum camera has been developed to record projectile in flight for observation and acquisition. It has two operation modes: (1) synchro-ballistic photography, (2) streak record. The film is located on the inner surface of rotating drum to make it travel. The folding mirror is arranged to reflect light beam 90 degree on to film. The assembly of folding mirror and slit aperture can be together rotated about the optical axis of objective so that the camera makes a feature of recording projectile having any launching angle either in synchro-ballistic photography or in streak record through prerotating the folding mirror assembly by an appropriate angle. The mechanical-electric shutter preventing film from reexposing is close to the slit aperture. The loading mechanism is designed for use in daylight. LED fiducial mark and timing mark are printed at the edges of the frame for accurate measurements.

  1. The aerodynamics of some guided projectiles

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.

    1984-01-01

    Some characteristic projectile shapes are considered with various added components intended to provide lift, stability, and control. The intent of the additions is to provide some means for altering the normal ballistic flight path of a projectile for various purposes such as: achieving greater accuracy at the impact point, selecting alternate impact points, extending range, improved evasion, and so on. The configurations presented illustrate the effects of a flare, wings, and tails for providing stability and lift, and the effects of aft-tails, a close-coupled flap, and all-moving forward wings for control. The relative merits of the various configurations, all of which provided for flight path alterations are discussed.

  2. Energy loss of hydrogen projectiles in gases

    SciTech Connect

    Schiefermueller, A.; Golser, R.; Stohl, R.; Semrad, D. )

    1993-12-01

    The stopping cross sections of H[sub 2], D[sub 2], He, and Ne for hydrogen projectiles in the energy range 3--20 keV per nucleon have been measured by time of flight. We compare our experimental result to the sum of the individual contributions due to excitation and ionization of the target and of the projectile, respectively, and due to charge exchange, using published cross-section data. Satisfactory agreement is found only for the He target and only at moderate projectile velocities, whereas for H[sub 2] and D[sub 2] the calculated values are about 30% too low. A Monte Carlo program allows us to simulate the measured time-of-flight spectra and to explain minor trends in the experimental data: for increased Ne gas pressure, an increased specific energy loss has been found that can be traced to different regions of impact parameters selected in our transmission geometry. This also explains, in part, the increased specific energy loss for deuterons compared to protons of equal velocity that is most evident for Ne. In contrast, a decrease of the specific energy loss with increasing pressure for He may be explained by impurities in the target gas. If we correct for the effect of impurities, the stopping cross section of He at 4 keV per nucleon is slightly smaller (0.60[times]10[sup [minus]15] eV cm[sup 2]) than published earlier (0.72[times]10[sup [minus]15] eV cm[sup 2]) and depends on the 3.8th power of projectile velocity.

  3. A hypervelocity projectile launcher for well perforation

    SciTech Connect

    Albright, J.N.; Fugelso, L.E.; Lagner, G.C.; Burns, K.L.

    1989-01-01

    Current oil well perforation techniques use low- to medium-velocity gun launchers for completing wells in soft rock. Shaped-charge jets are normally used in harder, more competent rock. A device to create a much higher velocity projectile was designed. This launcher will provide an alternative technique to be used when the conventional devices do not yield the maximum well performance. It is an adaptation of the axial cavity in a high explosive (HE) annulus design, with the axial cavity being filled with a low density foam material. Two configurations were tested; both had an HE annulus filled with organic foam, one had a projectile. Comparison of the two shots was made. A time sequence of Image Intensifier Camera photographs and sequential, orthogonal flash x-ray radiographs provided information on the propagation of the foam fragments, the first shock wave disturbance, the projectile motion and deformation, and the direct shock wave transmission from the main HE charge. DYNA2D calculations were made to assist in the experimental interpretation. 25 refs., 9 figs.

  4. Fragmentation of hypervelocity aluminum projectiles on fabrics

    NASA Astrophysics Data System (ADS)

    Rudolph, Martin; Schäfer, Frank; Destefanis, Roberto; Faraud, Moreno; Lambert, Michel

    2012-07-01

    This paper presents work performed for a study investigating the ability of different flexible materials to induce fragmentation of a hypervelocity projectile. Samples were chosen to represent a wide range of industrially available types of flexible materials like ceramic, aramid and carbon fabrics as well as a thin metallic mesh. Impact conditions and areal density were kept constant for all targets. Betacloth and multi-layer insulation (B-MLI) are mounted onto the targets to account for thermal system engineering requirements. All tests were performed using the Space light-gas gun facility (SLGG) of the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI. Projectiles were aluminum spheres with 5 mm diameter impacting at approximately 6.3 km/s. Fragmentation was evaluated using a witness plate behind the target. An aramid and a ceramic fabric lead the ranking of fabrics with the best projectile fragmentation and debris cloud dispersion performance. A comparison with an equal-density rigid aluminum plate is presented. The work presented can be applied to optimize the micrometeoroid and space debris (MM/SD) shielding structure of inflatable modules.

  5. Improvements to a model of projectile fragmentation

    NASA Astrophysics Data System (ADS)

    Mallik, S.; Chaudhuri, G.; Das Gupta, S.

    2011-11-01

    In a recent paper [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.83.044612 83, 044612 (2011)] we proposed a model for calculating cross sections of various reaction products which arise from disintegration of projectile-like fragments resulting from heavy-ion collisions at intermediate or higher energy. The model has three parts: (1) abrasion, (2) disintegration of the hot abraded projectile-like fragment (PLF) into nucleons and primary composites using a model of equilibrium statistical mechanics, and (3) possible evaporation of hot primary composites. It was assumed that the PLF resulting from abrasion has one temperature T. Data suggested that, while just one value of T seemed adequate for most cross-section calculations, a single value failed when dealing with very peripheral collisions. We have now introduced a variable T=T(b) where b is the impact parameter of the collision. We argue that there are data which not only show that T must be a function of b but, in addition, also point to an approximate value of T for a given b. We propose a very simple formula: T(b)=D0+D1[As(b)/A0] where As(b) is the mass of the abraded PLF and A0 is the mass of the projectile; D0 and D1 are constants. Using this model we compute cross sections for several collisions and compare with data.

  6. Forensic and clinical issues in the use of frangible projectile.

    PubMed

    Komenda, Jan; Hejna, Petr; Rydlo, Martin; Novák, Miroslav; Krajsa, Jan; Racek, František; Rejtar, Pavel; Jedlička, Luděk

    2013-08-01

    Frangible projectiles for firearms, which break apart on impact, are mainly used by law enforcement agencies for training purposes, but can also be used for police interventions. Apart from the usual absence of lead in the projectiles, the main advantage of using frangible projectiles is the reduced risk of ricochet after impact with a hard target. This article describes the design and function of frangible projectiles, and describes gunshot wounds caused by ultra-frangible projectiles which fragment after penetration of soft tissues. Shooting experiments performed by the authors confirmed that differences in the geometry and technology of frangible projectiles can significantly modify their wounding effects. Some frangible projectiles have minimal wounding effects because they remain compact after penetration of soft tissues, comparable to standard fully jacketed projectiles. However, a number of ultra-frangible projectiles disintegrate into very small fragments after impact with a soft tissue substitute. In shooting experiments, we found that the terminal behavior of selected ultra-frangible projectiles was similar in a block of ballistic gel and the soft tissues of the hind leg of a pig, except that the degree of disintegration was less in the gel.

  7. On the forces produced by oblique projectile impact

    SciTech Connect

    Yew, C.H.

    1995-12-31

    A mathematical model for calculating the force produced by projectile impact on terrestrial target was developed based on assumptions that (1) the projectile was rigid, and (2) the target material near the nose section was displaced normally to the nose surface by the penetrating projectile. The assumption suggested that the crater or tunnel produced by the penetrating projectile was similar to that produced by a series of dynamic spherical cavity expansions initiated at the nose tip, and the growth rate of cavities was restricted by the nose shape of the projectile and its penetrating velocity vector. The model allowed the calculation of pressure against the penetrating projectile by taking the inertia and the resistant pressure of the moving soil into consideration. The effect of projectile obliquity on pressure distribution on the nose section of projectile could also be calculated by relating the angle of attack and the angle of incidence to the rate of local radius change of the expanding cavity. Using this model, the time history of force vector exerted on the projectile as well as the corresponding trajectory of penetration were calculated. For a small angle of incidence, the calculated axial and lateral forces exerted on the nose of projectile showed a reasonable agreement with those measured from reverse ballistic impact tests. It was demonstrated that the magnitude of forces depended upon the impact velocity, the shape of projectile`s nose section, and the relative density between the projectile and the target material. There were no quantitative measurement of forces when the angle of incidence was large i.e., a shallow impact. For this case, the calculated forces were compared and discussed with the results from similitude analysis.

  8. ESA NEOCC effort to eliminate high Palermo Scale virtual impactors

    NASA Astrophysics Data System (ADS)

    Micheli, M.; Koschny, D.; Hainaut, O.; Bernardi, F.

    2014-07-01

    At the moment of this writing about 4 % of the known near-Earth objects are known to have at least one future close approach scenario with a non-negligible collision probability within the next century, as routinely computed by the NEODyS and Sentry systems. The most straightforward way to improve the knowledge of the future dynamics of an NEO in order to exclude (or possibly confirm) some of these possible future impact is to obtain additional astrometric observations of the object as soon as it becomes observable again. In particular, since a large fraction (>98 %) of the known objects currently recognized as possible future impactors have been observed during a single opposition, this usually corresponds to obtaining a new set of observations during a second opposition, a so called ''recovery''. However, in some cases the future observability windows for the target after the discovery apparition may be very limited, either because the object is intrinsically small (and therefore requires a very close and consequently rare approach to become observable) or because its orbital dynamic prevents the observability from the ground for a long timespan (as in the case of quasi-resonant objects with a long synodic period). When this happens, the only short-term way to clarify an impact scenario is to look toward the past, and investigate the possibility that unrecognized detections of the object are already present in the databases of old astronomical images, which are often archived by professional telescopes and made available to the community a few months to years after they are exposed. We will here present an effort lead by the newly formed ESA NEO Coordination Centre (NEOCC) in Frascati to pursue both these avenues with the intent of improving the orbital knowledge of the highest-rated possible impactors, as defined by the Palermo Technical Impact Hazard Scale (PS in the following). As an example of our ongoing observational activities, we will first present our

  9. Hign-speed penetration of projectile with cavitator into sand

    NASA Astrophysics Data System (ADS)

    Daurskikh, Anna; Veldanov, Vladislav

    2011-06-01

    Cavitators are used in underwater projectiles design to form a cavern in which projectile could move with no or significantly reduced drag. An investigation of possible application of this structural element for penetration into porous media was conducted. High-speed impact of a conical-shaped head projectile with cavitator was studied in terms of its influence on penetration capacity and projectile stability in sand for impact velocity about 1500 m/s. Cavitators were manufactured of steel with different strength moduli, and thus two penetration regimes (with eroding/non-eroding cavitator) were compared. Numerical simulations showing wave propagation in target and projectile were performed in AUTODYN with Johnson-Cook model for projectile and granular model for sand.

  10. Design and fabrication of projectiles for round bore railguns

    SciTech Connect

    Susoeff, A.R.; Hawke, R.S.

    1985-03-07

    A hypervelocity railgun system which operates in a vacuum and uses a gas gun injector to pre-accelerate the projectiles required that the projectile seal operate over wide pressure and velocity ranges. In our case, the helium gas gun injector operated at up to 35 MPa (5 ksi) while the railgun, using a plasma arc armature, operated at up to 150 MPa (22 ksi). In addition to gas and arc sealing, it was necessary that a metal fuse be attached to the rear of the projectile in order to electrically commutate the rails upon entry to the railgun. This paper discusses procedures and techniques in the design and fabrication of projectiles for a round bore railgun. It is divided into three sections: (1) machining the projectile; (2) fuse fabrication; and (3) assembly of the projectile/fuse package.

  11. Flight dynamics of a spinning projectile descending on a parachute

    SciTech Connect

    Benedetti, G.A.

    1989-02-01

    During the past twenty years Sandia National Laboratories and the US Army have vertically gun launched numerous 155mm and eight-inch diameter flight test projectiles. These projectiles are subsequently recovered using an on-board parachute recovery system which is attached to the forward case structure of the projectile. There have been at least five attempts to describe, through analytical and numerical simulations, the translational and rotational motions of a spinning projectile descending on a parachute. However, none of these investigations have correctly described the large nutational motion of the projectile since all of them overlooked the fundamental mechanism which causes these angular motions. Numerical simulations as well as a closed form analytical solution show conclusively that the Magnus moment is responsible for the large nutational motion of the projectile. That is, when the center of pressure for the Magnus force is aft of the center of mass for the projectile, the Magnus moment causes an unstable (or large) nutational motion which always tends to turn the spinning projectile upside down while it is descending on the parachute. Conversely, when the center of mass for the projectile is aft of the center of pressure for the Magnus force, the Magnus moment stabilizes the nutational motion tending to always point the base of the spinning projectile down. The results of this work are utilized to render projectile parachute recovery systems more reliable and to explain what initially may appear to be strange gyrodynamic behavior of a spinning projectile descending on a parachute. 14 refs., 20 figs.

  12. Design and testing of high-pressure railguns and projectiles

    SciTech Connect

    Peterson, D.R.; Fowler, C.M.; Cummings, C.E.; Kerrisk, J.F.; Parker, J.V.; Marsh, S.P.; Adams, D.F.

    1983-01-01

    The results of high-pressure tests of four railgun designs and four projectile types are presented. All tests were conducted at the Los Alamos explosive magnetic-flux compression facility in Ancho Canyon. The data suggest that the high-strength projectiles have lower resistance to acceleration than the low-strength projectiles, which expand against the bore during acceleration. The railguns were powered by explosive magnetic-flux compression generators. Calculations to predict railgun and power supply performance were performed.

  13. Developing Supersonic Impactor and Aerodynamic Lens for Separation and Handling of Nano-Sized Particles

    SciTech Connect

    Goodarz Ahmadi

    2008-06-30

    A computational model for supersonic flows of compressible gases in an aerodynamic lens with several lenses and in a supersonic/hypersonic impactor was developed. Airflow conditions in the aerodynamic lens were analyzed and contour plots for variation of Mach number, velocity magnitude and pressure field in the lens were evaluated. The nano and micro-particle trajectories in the lens and their focusing and transmission efficiencies were evaluated. The computational model was then applied to design of a aerodynamic lens that could generate focus particle beams while operating under atmospheric conditions. The computational model was also applied to airflow condition in the supersonic/hypersonic impactor. Variations of airflow condition and particle trajectories in the impactor were evaluated. The simulation results could provide understanding of the performance of the supersonic and hypersonic impactors that would be helpful for the design of such systems.

  14. Possible Impactor Remnants on Shatter Cone Surfaces from the Steinheim Basin, SW Germany

    NASA Astrophysics Data System (ADS)

    Buchner, E.; Schmieder, M.

    2015-07-01

    Surfaces of Steinheim shatter cones are covered by mineral coatings that consist of Fe, Ni, Co, Cu, Pt, and Au mineral assemblages. A plausible explanation is that they represent impactor matter remobilized in an impact-induced hydrothermal system.

  15. Design and testing of high-pressure railguns and projectiles

    NASA Technical Reports Server (NTRS)

    Peterson, D. R.; Fowler, C. M.; Cummings, C. E.; Kerrisk, J. F.; Parker, J. V.; Marsh, S. P.; Adams, D. F.

    1984-01-01

    Attention is given to the results of high-pressure tests involving four railgun designs and four projectile types. Explosive magnetic-flux compression generators were employed to power the railguns. On the basis of the experimental data, it appears that the high-strength projectiles have lower resistance to acceleration than low-strength projectiles, which expand against the bore during acceleration. While confined in the bore, polycarbonate projectiles can be subjected to pressures as high as 1.3 GPa without shattering. In multishot railguns, it is important to prevent an accumulation of sooty material from the plasma armature in railgun seams.

  16. Microcraters formed in glass by low density projectiles

    NASA Technical Reports Server (NTRS)

    Mandeville, J.-C.; Vedder, J. F.

    1971-01-01

    Microcraters were produced in soda-lime glass by the impact of low density projectiles of polystyrene with masses between 0.7 and 62 picograms and velocities between 2 and 14 kilometers per second. The morphology of the craters depends on the velocity and angle of incidence of the projectiles. The transitions in morphology of the craters formed by polystyrene spheres occur at higher velocities than they do for more dense projectiles. For oblique impact, the craters are elongated and shallow with the spallation threshold occuring at higher velocity. For normal incidence, the total displaced mass of the target material per unit of projectile kinetic energy increases slowly with the energy.

  17. Forensic imaging of projectiles using cone-beam computed tomography.

    PubMed

    von See, Constantin; Bormann, Kai-Hendrik; Schumann, Paul; Goetz, Friedrich; Gellrich, Nils-Claudius; Rücker, Martin

    2009-09-10

    In patients with gunshot injuries, it is easy to detect a projectile within the body due to the high-density of the object, but artefacts make it difficult to obtain information about the deformation and the exact location of the projectile in surrounding tissues. Cone-beam computed tomography (CBCT) is a new radiological imaging modality that allows radio-opaque objects to be localised and assessed in three dimensions. The full potential of the use of CBCT in forensic medicine has not yet been explored. In this study, three different modern projectiles were fired into the heads of pig cadavers (n=6) under standardised conditions. Tissue destruction and the location of the projectiles were analysed separately using CBCT and multi-slice computed tomography (MDCT). The projectiles had the same kinetic energy but showed considerable differences in deformation behaviour. Within the study groups, tissue destruction was reproducible. CBCT is less severely affected by metallic artefacts than MDCT. Therefore CBCT is superior in visualising bone destruction in the immediate vicinity of the projectile and projectile deformation, whereas MDCT allows soft tissue to be evaluated in more detail. CBCT is an improved diagnostic tool for the evaluation of gunshot injuries. In particular, it is superior to MDCT in detecting structural hard-tissue damage in the immediate vicinity of high-density metal projectiles and in identifying the precise location of a projectile in the body.

  18. Penetration into limestone targets with ogive-nose steel projectiles

    SciTech Connect

    Frew, D.J.; Green, M.L.; Forrestal, M.J.; Hanchak, S.J.

    1996-12-01

    We conducted depth of penetration experiments into limestone targets with 3.0 caliber-radius-head, 4340 Rc 45 steel projectiles. Powder guns launched two projectiles with length-to-diameter ratios of ten to striking velocities between 0.4 and 1.5 km/s. Projectiles had diameters and masses of 12.7 mm, 0. 117 kg and 25.4 mm, 0.610 kg. Based on data sets with these two projectile scales, we proposed an empirical penetration equation that described the target by its density and an empirical strength constant determined from penetration depth versus striking velocity data.

  19. Electric rail gun projectile acceleration to high velocity

    NASA Technical Reports Server (NTRS)

    Bauer, D. P.; Mccormick, T. J.; Barber, J. P.

    1982-01-01

    Electric rail accelerators are being investigated for application in electric propulsion systems. Several electric propulsion applications require that the rail accelerator be capable of launching projectiles at velocities above 10 km/s. An experimental program was conducted to develop rail accelerator technology for high velocity projectile launch. Several 6 mm bore, 3 m long rail accelerators were fabricated. Projectiles with a mass of 0.2 g were accelerated by plasmas, carrying currents up to 150 kA. Experimental design and results are described. Results indicate that the accelerator performed as predicted for a fraction of the total projectile acceleration. The disparity between predicted and measured results are discussed.

  20. Small carry-on impactor of Hayabusa2 mission

    NASA Astrophysics Data System (ADS)

    Saiki, Takanao; Sawada, Hirotaka; Okamoto, Chisato; Yano, Hajime; Takagi, Yasuhiko; Akahoshi, Yasuhiro; Yoshikawa, Makoto

    2013-03-01

    A Japanese spacecraft, Hayabusa2, the successor of Hayabusa, which came back from the Asteroid Itokawa with sample materials after its 7-year-interplanetary journeys, is a current mission of Japan Aerospace Exploration Agency (JAXA) and scheduled to be launched in 2014. Although its design basically follows Hayabusa, some new components are planned to be equipped in Hayabusa2 mission. A Small Carry-on Impactor (SCI), a small explosive device, is one of the challenges that were not seen with Hayabusa. An important scientific objective of Hayabusa2 is to investigate chemical and physical properties of the internal materials and structures. SCI creates an artificial crater on the surface of the asteroid and the mother spacecraft observes the crater and tries to get sample materials. High kinetic energy is required to creating a meaningful crater. The SCI would become complicated and heavy if the traditional acceleration devices like thrusters and rocket motors are used to hit the asteroid because the acceleration distance is quite large and guidance system is necessary. In order to make the system simpler, a technology of special type of shaped charge is used for the acceleration of the impact head. By using this technology, it becomes possible to accelerate the impact head very quickly and to hit the asteroid without guidance system. However, the impact operation should be complicated because SCI uses powerful explosive and it scatters high speed debris at the detonation. This paper presents the overview of our new small carry-on impact system and the impact operation of Hayabusa2 mission.

  1. Did Ordinary Chondrite Impactors Deliver Olivine to Vesta?

    NASA Astrophysics Data System (ADS)

    Le Corre, Lucille; Reddy, Vishnu; Sanchez, Juan A.; Cloutis, Edward A.; Izawa, Matthew R.; Mann, Paul

    2014-11-01

    Ground-based and Hubble Space Telescope observations of asteroid Vesta suggested the presence of olivine. However, subsequent analysis of data from NASA’s Dawn mission proved that this “olivine-bearing unit”, identified as Oppia crater and its ejecta blanket, was composed of HED impact melt rather than olivine. The lack of widespread olivine in the 19 km deep Rheasilvia basin on the South Pole suggests that the crust-mantle boundary was not breached during the formation of the basin, and that Vesta’s crust is thicker than originally anticipated. Recently, local-scale olivine units have been reported in the walls and ejecta of two craters, Arruntia and Bellicia, located in the northern hemisphere of Vesta, 350-430 km from the Rheasilvia basin (Ammannito et al., 2013). These units were interpreted as exposed plutons by Clenet et al. (2014) rather than of mantle origin excavated during the formation of the Rheasilvia basin. We explored alternative sources for these olivine-rich units by reanalyzing the data published by Ammannito et al. (2013). Our mineralogical analysis gives olivine abundance between 70-80 vol.% consistent with those obtained previously (>60%). The pyroxene ferrosilite content and olivine abundance of the olivine-rich units are similar to ordinary chondrites. Meteoritic evidence suggests contamination of HEDs by several ordinary chondrite impactors including H, L and LL chondrites. This includes howardite JaH 556, which contains ~20 vol.% H chondrite material mixed with HED impact melt. Based on the non-diagnostic curve match and detailed mineralogical analysis using diagnostic spectral band parameters, we conclude that the olivine units in the northern hemisphere of Vesta could be explained by the delivery of exogenic H/L chondrite material rather than being a product of planetary differentiation.

  2. Polarization phenomena in projectile fragmentation process

    SciTech Connect

    Matsuta, K.; Ozawa, A.; Nojiri, Y.; Minamisono, T.; Fukuda, M.; Kitagawa, A.; Momota, S.; Ohtsubo, T.; Matsuo, Y.; Takechi, H.; Fukuda, S.; Minami, I.; Sugimoto, K.; Tanihata, I.; Omata, K.; Alonso, J.R.; Krebs, G.F.; Symons, T.J.M.

    1992-03-01

    The nuclear spin polarization of beta-emitting fragments {sup 37}K and {sup 39} Ca has been measured at around the grazing angle of the {sup 40}Ca + Au collision at 106 MeV/u. Momentum dependence of the observed fragment polarization supports the idea that the origin of the polarization is the orbital angular momentum held by the fragment part of the projectile before the collision takes place. The sizable polarization of about 5% that was observed for the fragments will be a powerful tool for NMR study of the fragments.

  3. Fundamental Aerodynamic Investigations for Development of Arrow-Stabilized Projectiles

    NASA Technical Reports Server (NTRS)

    Kurzweg, Hermann

    1947-01-01

    The numerous patent applications on arrow-stabilized projectiles indicate that the idea of projectiles without spin is not new, but has appeared in various proposals throughout the last decades. As far as projectiles for subsonic speeds are concerned, suitable shapes have been developed for sometime, for example, numerous grenades. Most of the patent applications, though, are not practicable particularly for projectiles with supersonic speed. This is because the inventor usually does not have any knowledge of aerodynamic flow around the projectile nor any particular understanding of the practical solution. The lack of wind tunnels for the development of projectiles made it necessary to use firing tests for development. These are obviously extremely tedious or expensive and lead almost always to failures. The often expressed opinion that arrow-stabilized projectiles cannot fly supersonically can be traced to this condition. That this is not the case has been shown for the first time by Roechling on long projectiles with foldable fins. Since no aerodynamic investigations were made for the development of these projectiles, only tedious series of firing tests with systematic variation of the fins could lead to satisfactory results. These particular projectiles though have a disadvantage which lies in the nature cf foldable fins. They occasionally do not open uniformly in flight, thus causing unsymmetry in flow and greater scatter. The junctions of fins and body are very bad aerodynamically and increase the drag. It must be possible to develop high-performance arrow-stabilized projectiles based on the aerodynamic research conducted during the last few years at Peenemuende and new construction ideas. Thus the final shape, ready for operational use, could be developed in the wind tunnel without loss of expensive time in firing tests. The principle of arrow-stabilized performance has been applied to a large number of caliburs which were stabilized by various means Most

  4. Locating the source of projectile fluid droplets

    NASA Astrophysics Data System (ADS)

    Varney, Christopher R.; Gittes, Fred

    2011-08-01

    The ill-posed projectile problem of finding the source height from spattered droplets of viscous fluid is a longstanding obstacle to accident reconstruction and crime-scene analysis. It is widely known how to infer the impact angle of droplets on a surface from the elongation of their impact profiles. However, the lack of velocity information makes finding the height of the origin from the impact position and angle of individual drops not possible. From aggregate statistics of the spatter and basic equations of projectile motion, we introduce a reciprocal correlation plot that is effective when the polar launch angle is concentrated in a narrow range. The vertical coordinate depends on the orientation of the spattered surface and equals the tangent of the impact angle for a level surface. When the horizontal plot coordinate is twice the reciprocal of the impact distance, we can infer the source height as the slope of the data points in the reciprocal correlation plot. If the distribution of launch angles is not narrow, failure of the method is evident in the lack of linear correlation. We perform a number of experimental trials, as well as numerical calculations and show that the height estimate is relatively insensitive to aerodynamic drag. Besides its possible relevance for crime investigation, reciprocal-plot analysis of spatter may find application to volcanism and other topics and is most immediately applicable for undergraduate science and engineering students in the context of crime-scene analysis.

  5. Penetration of projectiles into granular targets.

    PubMed

    Ruiz-Suárez, J C

    2013-06-01

    Energetic collisions of subatomic particles with fixed or moving targets have been very valuable to penetrate into the mysteries of nature. But the mysteries are quite intriguing when projectiles and targets are macroscopically immense. We know that countless debris wandering in space impacted (and still do) large asteroids, moons and planets; and that millions of craters on their surfaces are traces of such collisions. By classifying and studying the morphology of such craters, geologists and astrophysicists obtain important clues to understand the origin and evolution of the Solar System. This review surveys knowledge about crater phenomena in the planetary science context, avoiding detailed descriptions already found in excellent papers on the subject. Then, it examines the most important results reported in the literature related to impact and penetration phenomena in granular targets obtained by doing simple experiments. The main goal is to discern whether both schools, one that takes into account the right ingredients (planetary bodies and very high energies) but cannot physically reproduce the collisions, and the other that easily carries out the collisions but uses laboratory ingredients (small projectiles and low energies), can arrive at a synergistic intersection point. PMID:23660625

  6. Effect of Projectile Diameter on Weldability of Impact Welding

    NASA Astrophysics Data System (ADS)

    Date, Hidefumi

    The impact welding has been carried out using the projectile with the diameter of 11 and 5 mm. The large projectile with the slenderness ratio L/d (L is Length and d is diameter) of 1 to 5 was welded to the stainless steel target. However, only the small projectile with the slenderness ratio less than 1.2 was welded to the same stainless steel target. In order to clarify the effect of the diameter of the projectile on the weldability, the temperature elevating process in the cylindrical projectile subjected to a longitudinal impact is evaluated numerically using LS-DYNA. The slenderness ratios used in the analysis were 1.0, 2.0 and 3.0. The coefficient of friction used in the analysis was 0.2. The constitutive equation used in the analysis was Cowper-Symonds type. Those numerical results indicated that the deformation mechanism of the projectile with the slenderness ratio less than 2.0 is different of that of the projectile with the slenderness ratio more than 2.0. It was clarified from those results that the temperature of the small projectile with the slenderness ratio less than 1.5 arrives at the bonding temperature by the difference of the deformation mechanism regardless of the small kinetic energy.

  7. Corrected Launch Speed for a Projectile Motion Laboratory

    ERIC Educational Resources Information Center

    Sanders, Justin M.; Boleman, Michael W.

    2013-01-01

    At our university, students in introductory physics classes perform a laboratory exercise to measure the range of a projectile fired at an assigned angle. A set of photogates is used to determine the initial velocity of the projectile (the launch velocity). We noticed a systematic deviation between the experimentally measured range and the range…

  8. Microcraters formed in glass by projectiles of various densities

    NASA Technical Reports Server (NTRS)

    Vedder, J. F.; Mandeville, J.-C.

    1974-01-01

    An experiment was conducted investigating the effect of projectile density on the structure and size of craters in soda lime glass and fused quartz. The projectiles were spheres of polystyrene-divinylbenzene (PS-DVB), aluminum, and iron with velocities between 0.5 and 15 km/sec and diameters between 0.4 and 5 microns. The projectile densities spanned the range expected for primary and secondary particles of micrometer size at the lunar surface, and the velocities spanned the lower range of micrometeoroid velocities and the upper range of secondary projectile velocities. There are changes in crater morphology as the impact velocity increases, and the transitions occur at lower velocities for the projectiles of higher density. The sequence of morphological features of the craters found for PS-DVB impacting soda lime glass for increasing impact velocity, described in a previous work (Mandeville and Vedder, 1971), also occurs in fused quartz and in both targets with the more dense aluminum and iron projectiles. Each transition in morphology occurs at impact velocities generating a certain pressure in the target. High density projectiles require a lower velocity than low-density projectiles to generate a given shock pressure.

  9. Characterization of inhalation aerosols: a critical evaluation of cascade impactor analysis and laser diffraction technique.

    PubMed

    de Boer, A H; Gjaltema, D; Hagedoorn, P; Frijlink, H W

    2002-12-01

    Cascade impactor analysis is the standard technique for in vitro characterization of aerosol clouds generated by medical aerosol generators. One important reason for using this inertial separation principle is that drug fractions are classified into aerodynamic size ranges that are relevant to the deposition in the respiratory tract. Measurement of these fractions with chemical detection methods enables establishment of the particle size distribution of the drug in the presence of excipients. However, the technique is laborious and time consuming and most of the devices used for inhaler evaluation lack sufficient possibilities for automation. In addition to that, impactors often have to be operated under conditions for which they were not designed and calibrated. Particularly, flow rates through impactors are increased to values at which the flow through the nozzles is highly turbulent. This has an uncontrolled influence on the collection efficiencies and cut-off curves of these nozzles. Moreover, the cut-off value varies with the flow rate through an impactor nozzle. On the other hand, the high air flow resistances of most impactors are rather restricting to the attainable (fixed) inspiratory flow curves through these devices. Especially for breath actuated dry powder inhalers, higher flow rates and flow increase rates may be desirable than can be achieved in combination with a particular type of impactor. In this paper, the applicability of laser diffraction technology is evaluated as a very fast and highly reliable alternative for cascade impactor analysis. With this technique, aerodynamic diameters cannot be measured, but for comparative evaluation and development, comprising most in vitro applications, this is not necessary. Laser diffraction has excellent possibilities for automated recording of data and testing conditions, and the size classes are independent of the flow rate. Practical limitations can be overcome by using a special inhaler adapter which

  10. Modified point mass trajectory simulation for base-burn projectiles

    NASA Astrophysics Data System (ADS)

    Lieske, R. F.; Danberg, J. E.

    1992-03-01

    An addition to the Modified Point Mass Trajectory Model for Rocket-Assisted Projectiles is presented for the exterior ballistic simulation of base-burn projectiles. The addition models the change in aerodynamic base-drag based on the change in base pressure due to the base-burn motor's ejection of hot gas into the wake of the projectile. The mass flow rate of the remaining fuel of the base-burn motor is modeled as a function of the instantaneous projectile spin rate and atmospheric air pressure. HAWK Doppler radar data collected at Yuma Proving Ground, Arizona, for the 155mm, M1864 base-burn projectile were used to verify the modeling approach for a variety of test conditions.

  11. The penetration performance of short L/D projectiles

    NASA Astrophysics Data System (ADS)

    Anderson, Charles E.; Littlefield, David L.; Blaylock, Neil W.; Bless, Stephan J.; Subramanian, Ravi

    1994-07-01

    The depths of penetration normalized by the original projectile length for steel, tungsten alloy, and aluminum projectiles, as a function of impact velocity have been studied to obtain scaling relationships of projectile and target densities, impact velocity, and target flow stress for relatively short length-to-diameter ratio (L/D≤6) projectiles. It is demonstrated, using a fairly extensive set of experimental data, the nondimensional terms can ``collapse'' the data into a family of curves that differ only by the aspect ratio (L/D) of the projectiles. Regression fits were performed to provide analytical expressions for the reduced penetration efficiency in terms of the nondimensional impact terms. Finally, the results of numerical simulations and independent experiments were found to agree quite well with the regression fits.

  12. Turbulent Flow Past Projectiles: A Computational Investigation

    NASA Astrophysics Data System (ADS)

    Mehmedagic, Igbal; Carlucci, Donald; Buckley, Liam; Carlucci, Pasquale; Thangam, Siva

    2010-11-01

    Projectiles with free spinning bases are often used for smart munitions to provide effective control, stability and terminal guidance. Computational investigations are performed for flow past cylinders aligned along their axis where a base freely spins while attached to and separated at various distances from a non-spinning fore-body. The energy spectrum is modified to incorporate the effects of swirl and rotation using a parametric characterization of the model coefficients. An efficient finite-volume algorithm is used to solve the time-averaged equations of motion and energy along with the modeled form of transport equations for the turbulence kinetic energy and the scalar form of turbulence dissipation. Computations are performed for both rigid cylinders as well as cylinders with free-spinning bases. Experimental data for a range of spin rates and free stream flow conditions obtained from subsonic wind tunnel with sting-mounted spinning cylinders is used for validating the computational findings.

  13. Evaluation of an abbreviated impactor for fine particle fraction (FPF) determination of metered dose inhalers (MDI).

    PubMed

    Guo, Changning; Ngo, Diem; Ahadi, Shafiq; Doub, William H

    2013-09-01

    Abbreviated impactors have been developed recently to allow more rapid evaluation of inhalation products as alternates to the eight-stage Andersen Cascade Impactor (ACI) which has been widely used in the pharmaceutical industry for assessing aerodynamic particle size distribution. In this paper, a two-stage abbreviated impactor, Westech Fine Particle Dose Impactor (WFPD), was used to characterize the aerodynamic particle size of metered dose inhaler (MDI) products, and the results were compared with those obtained using the standard eight-stage ACI. Seven commercial MDI products, with different propellants (chlorofluorocarbon/hydrofluoroalkane) and formulation types (suspension/solution, dry/normal/wet), were tested in this study by both WFPD and ACI. Substantially equivalent measures of fine particle fraction were obtained for most of the tested MDI products, but larger coarse particle fraction and extra-fine particle fraction values were measured from WFPD relative to those measured using the ACI. Use of the WFPD also produced more wall loss than the ACI. Therefore, it is recommended that the system suitability be evaluated on a product-by-product basis to establish substantial equivalency before implementing an abbreviated impactor measurement methodology for routine use in inhaler product characterization. PMID:23780781

  14. Design and Use of a Guided Weight Impactor to Impart Barely Visible Impact Damage

    NASA Technical Reports Server (NTRS)

    Lovejoy, Andrew E.; Przekop, Adam

    2016-01-01

    Aircraft structure is required to demonstrate satisfaction of the FAR requirements for Category 1, such as barely visible impact damage (BVID). Typical aircraft structure is impacted using a dropped weight impactor, which can impart BVID to the top surface of the structure. A recent test of a multi-bay box (MBB) composite test article, that represents an 80% scale center section of a hybrid wing body aircraft, required impact to be in a direction other than vertical from above, but still in an direction that is normal to the surface. This requirement eliminated the use of the conventional dropped weight impactor. Therefore, a design study was undertaken to determine the most effective way to efficiently and reliably impact the MBB. The chosen design was a guided weight impactor that is gravity driven. This paper describes the design of the guided weight impactor, and presents the results of its use for imparting BVID to the MBB. The guided weight impactor was seen to be a very reliable method to impart BVID, while at the same time having the capability to be highly configurable for use on other aircraft structure that is impacted at a variety of impact energies and from a variety of directions.

  15. Response of laminated composite plates to low-speed impact by different impactors

    NASA Technical Reports Server (NTRS)

    Prasad, Chunchu; Ambur, Damodar R.; Starnes, James H.

    1994-01-01

    An analytic procedure has been developed to determine the transient response of simply supported, retangular laminated composite plates subjected to impact loads from airgun-propelled or drop-weight impactors. A first-order shear deformation theory has been included in the analysis to represent properly any local short-wavelength transient bending response. The impact force has been modeled as a locally distributed load with cosine-cosine distribution. A double Fourier series expansion and the Timoshenko small increment method have been used to determine the contact force, out-of-plane deflections, and in-plane strains and stresses at any plate location due to an impact force at any plate location. The results of experimental and analytical studies are compared for quasi-isotropic laminates. The results indicate the importance of including transverse shear deformation effects in the analysis for predicting the response of laminated plates subjected to both airgun-propelled and dropped-weight impactors. The results also indicate that plate boundary conditions influence the axial strains more significantly than the contact force for a dropped-weight impactor. The results of parametric studies identify a scaling approach based on impactor momentum that may account for the differences in the responses of plates impacted by airgun-propelled or dropped-weight impactors.

  16. Evaluation of an abbreviated impactor for fine particle fraction (FPF) determination of metered dose inhalers (MDI).

    PubMed

    Guo, Changning; Ngo, Diem; Ahadi, Shafiq; Doub, William H

    2013-09-01

    Abbreviated impactors have been developed recently to allow more rapid evaluation of inhalation products as alternates to the eight-stage Andersen Cascade Impactor (ACI) which has been widely used in the pharmaceutical industry for assessing aerodynamic particle size distribution. In this paper, a two-stage abbreviated impactor, Westech Fine Particle Dose Impactor (WFPD), was used to characterize the aerodynamic particle size of metered dose inhaler (MDI) products, and the results were compared with those obtained using the standard eight-stage ACI. Seven commercial MDI products, with different propellants (chlorofluorocarbon/hydrofluoroalkane) and formulation types (suspension/solution, dry/normal/wet), were tested in this study by both WFPD and ACI. Substantially equivalent measures of fine particle fraction were obtained for most of the tested MDI products, but larger coarse particle fraction and extra-fine particle fraction values were measured from WFPD relative to those measured using the ACI. Use of the WFPD also produced more wall loss than the ACI. Therefore, it is recommended that the system suitability be evaluated on a product-by-product basis to establish substantial equivalency before implementing an abbreviated impactor measurement methodology for routine use in inhaler product characterization.

  17. Trajectory Control of Small Rotating Projectiles by Laser Sparks

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Limbach, Christopher; Miles, Richard

    2015-09-01

    The possibility of controlling the trajectory of the supersonic motion of a rotating axisymmetric projectile using a remotely generated laser spark was investigated. The dynamic images of the interaction of thermal inhomogeneity created by the laser spark with the bow shock in front of the projectile were obtained. The criterion for a strong shock wave interaction with the thermal inhomogeneity at different angles of a shock wave was derived. Significant changes in the configuration of the bow shock wave and changes in the pressure distribution over the surface of the rotating projectile can appear for laser spark temperature of T' = 2500-3000 K. The experiment showed that strong interaction takes place for both plane and oblique shock waves. The measurement of the velocity of the precession of the rotating projectile axis from the initial position in time showed that the angle of attack of the projectile deviates with a typical time of perturbation propagation along the projectile's surface. Thus the laser spark can change the trajectory of the rotating projectile, moving at supersonic speed, through the creation of thermal heterogeneity in front of it.

  18. Experimental and numerical study on fragmentation of steel projectiles

    NASA Astrophysics Data System (ADS)

    Råkvaag, K. G.; Børvik, T.; Hopperstad, O. S.; Westermann, I.

    2012-08-01

    A previous experimental study on penetration and perforation of circular Weldox 460E target plates with varying thicknesses struck by blunt-nose projectiles revealed that fragmentation of the projectile occurred if the target thickness or impact velocity exceeded a certain value. Thus, numerical simulations that do not account for fragmentation during impact can underestimate the perforation resistance of protective structures. Previous numerical studies have focused primarily on the target plate behaviour. This study considers the behaviour of the projectile and its possible fragmentation during impact. Hardened steel projectiles were launched at varying velocities in a series of Taylor tests. The impact events were captured using a high-speed camera. Fractography of the fragmented projectiles showed that there are several fracture mechanisms present during the fragmentation process. Tensile tests of the projectile material revealed that the hardened material has considerable variations in yield stress and fracture stress and strain. In the finite element model, the stress-strain behaviour from tensile tests was used to model the projectile material with solid elements and the modified Johnson-Cook constitutive relation. Numerical simulations incorporating the variations in material properties are capable of reproducing the experimental fracture patterns, albeit the predicted fragmentation velocities are too low.

  19. Veterinary Forensics: Firearms and Investigation of Projectile Injury.

    PubMed

    Bradley-Siemens, N; Brower, A I

    2016-09-01

    Projectile injury represents an estimated 14% of reported animal cruelty cases in the United States. Cases involving projectiles are complicated by gross similarities to other common types of injury, including bite wounds and motor vehicle injuries, by weapons and ammunition not commonly recognized or understood by veterinary medical professionals, and by required expertise beyond that employed in routine postmortem examination. This review describes the common types of projectile injuries encountered within the United States, as well as firearms and ammunition associated with this form of injury. The 3 stages of ballistics-internal, external, and terminal-and wounding capacity are discussed. A general understanding of firearms, ammunition, and ballistics is necessary before pursuing forensic projectile cases. The forensic necropsy is described, including gunshot wound examination, projectile trajectories, different imaging procedures, collection and storage of projectile evidence, and potential advanced techniques for gunpowder analysis. This review presents aspects of projectile injury investigation that must be considered in tandem with standard postmortem practices and procedures to ensure reliable conclusions are reached for medicolegal as well as diagnostic purposes.

  20. Veterinary Forensics: Firearms and Investigation of Projectile Injury.

    PubMed

    Bradley-Siemens, N; Brower, A I

    2016-09-01

    Projectile injury represents an estimated 14% of reported animal cruelty cases in the United States. Cases involving projectiles are complicated by gross similarities to other common types of injury, including bite wounds and motor vehicle injuries, by weapons and ammunition not commonly recognized or understood by veterinary medical professionals, and by required expertise beyond that employed in routine postmortem examination. This review describes the common types of projectile injuries encountered within the United States, as well as firearms and ammunition associated with this form of injury. The 3 stages of ballistics-internal, external, and terminal-and wounding capacity are discussed. A general understanding of firearms, ammunition, and ballistics is necessary before pursuing forensic projectile cases. The forensic necropsy is described, including gunshot wound examination, projectile trajectories, different imaging procedures, collection and storage of projectile evidence, and potential advanced techniques for gunpowder analysis. This review presents aspects of projectile injury investigation that must be considered in tandem with standard postmortem practices and procedures to ensure reliable conclusions are reached for medicolegal as well as diagnostic purposes. PMID:27312366

  1. Comparison of coal ash particle size distributions from Berner, and Dekati low pressure impactors

    SciTech Connect

    Wang, C.M.; Seames, W.S.; Gadgil, M.; Hrdlicka, J.; Fix, G.

    2007-12-15

    This article presents the differential mass size distributions of coal combustion particulate matter (PM) determined with the Berner low-pressure impactor (BLPI, Hauke Model 25-410.015) and a newer generation of low pressure impactor, the Dekati low-pressure impactor (DLPI, Dekati Ltd Model 6281). The collection characteristics of the BLPI and DLPI are compared and cutoff diameters are calculated. Samples were collected in the post-combustion zone of a 19 kW vertical downflow combustor from two coal types. Both BLPI and DLPI represent a tri-modal distribution and give statistically similar characterizations of the coal ash particle size distribution. Distributions generated from DLPI data have higher fractions of submicron particles compared to those generated from BLPI data. The DLPI's two additional stages may provide greater resolution in the submicron region than the BLPI.

  2. Adaptation of a Cascade Impactor to Flight Measurement of Droplet Size in Clouds

    NASA Technical Reports Server (NTRS)

    Levine, Joseph; Kleinknecht, Kenneth S.

    1951-01-01

    A cascade impactor, an instrument for obtaining: the size distribution of droplets borne in a low-velocity air stream, was adapted for flight cloud droplet-size studies. The air containing the droplets was slowed down from flight speed by a diffuser to the inlet-air velocity of the impactor. The droplets that enter the impactor impinge on four slides coated with magnesium oxide. Each slide catches a different size range. The relation between the size of droplet impressions and the droplet size was evaluated so that the droplet-size distributions may be found from these slides. The magnesium oxide coating provides a permanent record. of the droplet impression that is not affected by droplet evaporation after the. droplets have impinged.

  3. The ISIS Mission Concept: An Impactor for Surface and Interior Science

    NASA Technical Reports Server (NTRS)

    Chesley, Steven R.; Elliot, John O.; Abell, Paul A.; Asphaug, Erik; Bhaskaran, Shyam; Lam, Try; Lauretta, Dante S.

    2013-01-01

    The Impactor for Surface and Interior Science (ISIS) mission concept is a kinetic asteroid impactor mission to the target of NASA's OSIRIS-REx (Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer) asteroid sample return mission. The ISIS mission concept calls for the ISIS spacecraft, an independent and autonomous smart impactor, to guide itself to a hyper-velocity impact with 1999 RQ36 while the OSIRIS-REx spacecraft observes the collision. Later the OSIRIS-REx spacecraft descends to reconnoiter the impact site and measure the momentum imparted to the asteroid through the impact before departing on its journey back to Earth. In this paper we discuss the planetary science, human exploration and impact mitigation drivers for mission, and we describe the current mission concept and flight system design.

  4. Effect of resistance on projectile oscillations in augmented rail guns

    SciTech Connect

    Hodgdon, M.L.; Fowler, C.M.; Homan, C.G.

    1986-01-01

    Approximate solutions for the equation of motion of a projectile in an augmented rail gun are presented. These solutions show that the resistance in the rail gun system plays a role similar to the resistance in an R-C-L circuit. For small values of resistance, the projectile exhibits a slightly damped oscillatory motion, and there is a value of resistance for which the oscillations disappear and the motion appears critically damped. The dependence of the oscillations on the projectile mass and the augmenting field are also discussed.

  5. The projectile-wall interface in rail launchers

    NASA Astrophysics Data System (ADS)

    Thio, Y. C.; Huerta, M. A.; Boynton, G. C.; Tidman, D. A.; Wang, S. Y.; Winsor, N. K.

    1993-01-01

    At sufficiently high velocity, an energetic gaseous interface is formed between the projectile and the gun wall. We analyze the flow in this interface in the regime of moderately high velocity. The effect of this gaseous interface is to push the gun wall radially outward and shrink the projectile radially inward. Our studies show that significant plasma blow-by can be expected in most experimental railguns in which organic polymers are used as insulators. Since plasma leakage may result in the reduction of propulsion pressure and possibly induce the separation of the primary, the results point to the importance of having sufficiently stiff barrels and structurally stiff but 'ballistically compliant' projectile designs.

  6. Three-Dimensional Shapes and Impactor Size Estimation of Stardust Impact

    NASA Technical Reports Server (NTRS)

    Iida, Y.; Tsuchiyama, A.; Kadono, T.; Nakamura, T.; Sakamoto, K.; Nakano, T.; Uesugi, K.; Zolensky, M. E.

    2008-01-01

    Impact tracks formed by cometary dust capture in silica aerogel collectors in the Stardust mission [1] have a variety of shapes, showing diversity of the cometary dust [2]. We have investigated 3-D structures and elemental distributions of three impact tracks using synchrotron radiation x-ray analyses (microtomography and XRF) as one of the preliminary examination [3]. In this study, additional five tracks were investigated by the same analytical method. Impactor sizes of the tracks were estimated from the track entrance sizes and Fe abundances. Size parameters, such as length, of the tracks were normalized by the impactor size to compare track shape

  7. Calibration of the QCM/SAW Cascade Impactor for Measurement of Ozone

    NASA Technical Reports Server (NTRS)

    Williams, Cassandra K.; Peterson, C. B.; Morris, V. R.

    1997-01-01

    The Quartz Crystal Microbalance Surface Acoustic Wave (QCM/SAW) cascade impactor is an instrument designed to collect size-fractionated distributions of aerosols on a series of quartz crystals and employ SAW devices coated with chemical sensors for gas detection. We are calibrating the cascade impactor in our laboratory for future deployment for in-situ experiments to measure ozone. Experiments have been performed to characterize the QCM and SAW mass loading, saturation limits, mass frequency relationships, and sensitivity. The characteristics of mass loading, saturation limits, mass-frequency relationships, sensitivity, and the loss of ozone on different materials have been quantified.

  8. Comparison of less lethal 40 mm sponge projectile and the 37 mm projectile for injury assessment on human thorax

    NASA Astrophysics Data System (ADS)

    Nsiampa, N.; Robbe, C.; Oukara, A.; Papy, A.

    2012-08-01

    Since there is an increasing interest in avoiding human body injury in diverse situations like crowd control or peacekeeping missions, less lethal ammunition are more and more used. In this study we focus only on kinetic energy non-lethal (KENLW) projectiles. Their desired effects on human body are the temporary incapacitation through blunt trauma. There are different types of KENLW projectiles ranging from rigid to deformable projectiles. Unfortunately, the effects of such projectiles are not really well known as it is difficult to measure the force transmitted to the human body or the related deformation. Because the potential of injury excludes human living tests, tests are performed on cadavers, animals or human tissue surrogates. Besides these tests, numerical simulations are more and more used to gain more understanding, to assess or to predict the effects of this kind of projectile on human body. In this paper a comparison based on the viscous criterion between the 37 mm rigid projectile and the 40 mm sponge projectile was made.

  9. Measurement of sound emitted by flying projectiles with aeroacoustic sources

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Shakkottai, P.; Harstad, K. G.; Back, L. H.

    1988-01-01

    Training projectiles with axisymmetric ring cavities that produce intense tones in an airstream were shot in a straight-line trajectory. A ground-based microphone was used to obtain the angular distribution of sound intensity produced from the flying projectile. Data reduction required calculation of Doppler and attenuation factors. Also, the directional sensitivity of the ground-mounted microphone was measured and used in the data reduction. A rapid angular variation of sound intensity produced from the projectile was found that can be used to plot an intensity contour map on the ground. A full-scale field test confirmed the validity of the aeroacoustic concept of producing a relatively intense whistle from the projectile, and the usefulness of short-range flight tests that yield acoustic data free of uncertainties associated with diffraction, reflection, and refraction at jet boundaries in free-jet tests.

  10. 22. Emplacement no. 1 showing well for projectile hoist at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Emplacement no. 1 showing well for projectile hoist at right. at left is passage toward the shot gallery. View looking northwest - Fort Wadsworth Battery Romeyn B. Ayers, South side of Ayers Road, Staten Island, Rosebank, Richmond County, NY

  11. Guiding supersonic projectiles using optically generated air density channels

    NASA Astrophysics Data System (ADS)

    Johnson, Luke A.; Sprangle, Phillip

    2015-09-01

    We investigate the feasibility of using optically generated channels of reduced air density to provide trajectory correction (guiding) for a supersonic projectile. It is shown that the projectile experiences a force perpendicular to its direction of motion as one side of the projectile passes through a channel of reduced air density. A single channel of reduced air density can be generated by the energy deposited from filamentation of an intense laser pulse. We propose changing the laser pulse energy from shot-to-shot to build longer effective channels. Current femtosecond laser systems with multi-millijoule pulses could provide trajectory correction of several meters on 5 km trajectories for sub-kilogram projectiles traveling at Mach 3.

  12. Oblique impact: Projectile richochet, concomitant ejecta and momentum transfer

    NASA Technical Reports Server (NTRS)

    Gault, Donald E.; Schultz, Peter H.

    1987-01-01

    Experimental studies of oblique impact indicate that projectile richochet occurs for trajectory angles less than 30 deg and that the richocheted projectile, accompanied by some target material, are ejected at velocities that are a large fraction of the impact velocity. Because the probability of occurrence of oblique impact less than 30 deg on a planetary body is about one out of every four impact events, oblique impacts would seem to be a potential mechanism to provide a source of meteorites from even the largest atmosphere-free planetary bodies. Because the amount of richocheted target material cannot be determined from previous results, additional experiments in the Ames Vertical Gun laboratory were undertaken toward that purpose using pendulums; one to measure momentum of the richocheted projectile and concomitant target ejecta, and a second to measure the momentum transferred from projectile to target. These experiments are briefly discussed.

  13. 2. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER, PROJECTILE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER, PROJECTILE LOADING DECK AND BREECH END OF LAUNCHER BRIDGE LOOKING SOUTH. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  14. 32. VAL, DETAIL SHOWING LOADING PLATFORM, PROJECTILE LOADING CAR, LAUNCHER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. VAL, DETAIL SHOWING LOADING PLATFORM, PROJECTILE LOADING CAR, LAUNCHER SLAB AND UNDERSIDE OF LAUNCHER BRIDGE LOOKING SOUTHWEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  15. 3. VAL PROJECTILE LOADING DECK, SUPPORT CARRIAGE AND LAUNCHING BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VAL PROJECTILE LOADING DECK, SUPPORT CARRIAGE AND LAUNCHING BRIDGE LOOKING SOUTHWEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  16. 16. VAL PROJECTILE LOADING DECK AND VIEW OF RESERVOIR LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VAL PROJECTILE LOADING DECK AND VIEW OF RESERVOIR LOOKING SOUTHWEST WITH MORRIS DAM IN THE DISTANCE. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  17. 15. VAL, DETAIL OF SUPPORT CARRIAGE, PROJECTILE LOADING DECK AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. VAL, DETAIL OF SUPPORT CARRIAGE, PROJECTILE LOADING DECK AND THE BREECH END OF THE LAUNCHER BRIDGE LOOKING NORTHWEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  18. 17. VAL PROJECTILE LOADING DECK AND BREECH END OF LAUNCHER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. VAL PROJECTILE LOADING DECK AND BREECH END OF LAUNCHER BRIDGE LOOKING SOUTH. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  19. Penetration analysis of projectile with inclined concrete target

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Kim, H. W.; Yoo, Y. H.

    2015-09-01

    This paper presents numerical analysis result of projectile penetration with concrete target. We applied dynamic material properties of 4340 steels, aluminium and explosive for projectile body. Dynamic material properties were measured with static tensile testing machine and Hopkinson pressure bar tests. Moreover, we used three concrete damage models included in LS-DYNA 3D, such as SOIL_CONCRETE, CSCM (cap model with smooth interaction) and CONCRETE_DAMAGE (K&C concrete) models. Strain rate effect for concrete material is important to predict the fracture deformation and shape of concrete, and penetration depth for projectiles. CONCRETE_DAMAGE model with strain rate effect also applied to penetration analysis. Analysis result with CSCM model shows good agreement with penetration experimental data. The projectile trace and fracture shapes of concrete target were compared with experimental data.

  20. Dynamics of dust-free cavities behind fast projectiles in a dusty plasma under microgravity conditions

    SciTech Connect

    Caliebe, D.; Arp, O.; Piel, A.

    2011-07-15

    The penetration of a dusty plasma by fast charged projectiles is studied under microgravity conditions. The mass and charge of the projectiles are larger than those of the target particles. A projectile generates a dust-free cavity in its wake, whose shape strongly depends on the projectile velocity. The faster the projectile the more elongated becomes the cavity while its cross-section decreases. The opening time of the cavity is found independent of the projectile velocity. For supersonic projectiles, the dynamics of the cavity can be decomposed into an initial impulse and a subsequent elastic response that can be modeled by a damped harmonic oscillator.

  1. Microscopic impactor debris in the soil around Kamil crater (Egypt): Inventory, distribution, total mass, and implications for the impact scenario

    NASA Astrophysics Data System (ADS)

    Folco, Luigi; D'Orazio, Massimo; Fazio, Agnese; Cordier, Carole; Zeoli, Antonio; Ginneken, Matthias; El-Barkooky, Ahmed

    2015-03-01

    We report on the microscopic impactor debris around Kamil crater (45 m in diameter, Egypt) collected during our 2010 geophysical expedition. The hypervelocity impact of Gebel Kamil (Ni-rich ataxite) on a sandstone target produced a downrange ejecta curtain of microscopic impactor debris due SE-SW of the crater (extending ~300,000 m2, up to ~400 m from the crater), in agreement with previous determination of the impactor trajectory. The microscopic impactor debris include vesicular masses, spherules, and coatings of dark impact melt glass which is a mixture of impactor and target materials (Si-, Fe-, and Al-rich glass), plus Fe-Ni oxide spherules and mini shrapnel, documenting that these products can be found in craters as small as few tens of meters in diameter. The estimated mass of the microscopic impactor debris (<290 kg) derived from Ni concentrations in the soil is a small fraction of the total impactor mass (~10 t) in the form of macroscopic shrapnel. That Kamil crater was generated by a relatively small impactor is consistent with literature estimates of its pre-atmospheric mass (>20 t, likely 50-60 t).

  2. Orientation estimation algorithm applied to high-spin projectiles

    NASA Astrophysics Data System (ADS)

    Long, D. F.; Lin, J.; Zhang, X. M.; Li, J.

    2014-06-01

    High-spin projectiles are low cost military weapons. Accurate orientation information is critical to the performance of the high-spin projectiles control system. However, orientation estimators have not been well translated from flight vehicles since they are too expensive, lack launch robustness, do not fit within the allotted space, or are too application specific. This paper presents an orientation estimation algorithm specific for these projectiles. The orientation estimator uses an integrated filter to combine feedback from a three-axis magnetometer, two single-axis gyros and a GPS receiver. As a new feature of this algorithm, the magnetometer feedback estimates roll angular rate of projectile. The algorithm also incorporates online sensor error parameter estimation performed simultaneously with the projectile attitude estimation. The second part of the paper deals with the verification of the proposed orientation algorithm through numerical simulation and experimental tests. Simulations and experiments demonstrate that the orientation estimator can effectively estimate the attitude of high-spin projectiles. Moreover, online sensor calibration significantly enhances the estimation performance of the algorithm.

  3. DESIGN AND CALIBRATION OF THE EPA PM 2.5 WELL IMPACTOR NINETY-SIX (WINS)

    EPA Science Inventory

    The EPA well-type impactor ninety-six (WINS) was designed and calibrated to serve as a particle size separation device for the EPA reference method sampler for particulate matter under 2.5 um aerodynamic diameter. The WINS was designed to operate downstream of a PM10 inlet at a...

  4. Noble Gas Isotopes: Tracers of Impactor Signatures in Lonar Impact Glasses

    NASA Astrophysics Data System (ADS)

    Murty, S. V. S.; Ranjit Kumar, P. M.

    2012-03-01

    Noble gas isotopes ^2^1Ne, ^3^6Ar, and ^1^2^9Xe reveal excesses due to the presence of cosmogenic, trapped, and radiogenic components of meteoritic origin, in the impact glasses from Lonar Crater, providing unambiguous signatures of the impactor.

  5. An estimate of spherical impactor energy transfer for mechanical frequency up-conversion energy harvester

    NASA Astrophysics Data System (ADS)

    Corr, L. R.; Ma, D. T.

    2016-08-01

    Vibration energy harvesters, which use the impact mechanical frequency up-conversion technique, utilize an impactor, which gains kinetic energy from low frequency ambient environmental vibrations, to excite high frequency systems that efficiently convert mechanical energy to electrical energy. To take full advantage of the impact mechanical frequency up-conversion technique, it is prudent to understand the energy transfer from the low frequency excitations, to the impactor, and finally to the high frequency systems. In this work, the energy transfer from a spherical impactor to a multi degree of freedom spring / mass system, due to Hertzian impact, is investigated to gain insight on how best to design impact mechanical frequency up-conversion energy harvesters. Through this academic work, it is shown that the properties of the contact (or impact) area, i.e., radius of curvature and material properties, only play a minor role in energy transfer and that the equivalent mass of the target system (i.e., the spring / mass system) dictates the total amount of energy transferred during the impact. The novel approach of utilizing the well-known Hertzian impact methodology to gain an understanding of impact mechanical frequency up-conversion energy harvesters has made it clear that the impactor and the high frequency energy generating systems must be designed together as one system to ensure maximum energy transfer, leading to efficient ambient vibration energy harvesters.

  6. On the Nature of the Impactor That Formed the Shackleton Crater on the Moon

    NASA Astrophysics Data System (ADS)

    Pugacheva, Svetlana G.; Feoktistova, Ekaterina A.; Shevchenko, Vladislav V.

    2016-06-01

    The present paper attempts to assess the characteristics of the impactor that formed the Shackleton crater, located at the south pole of the Moon. The crater's morphometric parameters were analyzed based on the data of the Lunar Orbiter Laser Altimeter aboard the Lunar Reconnaissance Orbiter. Conclusions were drawn regarding the possible range of the impact angle and the parameters of the transient crater, such as depth and volume. The thickness of ejecta deposits on the transient crater rim and the volume of these deposits at a certain distance from the crater rim were assessed. These assessments enabled determining the type and characteristics of impactors (velocity, density, size, and impact angle) that could have formed the Shackleton crater. It was shown that the Shackleton crater could have been formed by an impact of a low-velocity (3 km/s) comets with diameter 4-4.5 km, chondrite or achondrite with a diameter of 2 km at a 45°-50° angle, whose velocity did not exceed 6 km/s, as well as stony-iron or iron-nickel impactors with a 1-2 km diameter for stony-iron asteroids and 1-1.5 km for iron-nickel asteroids. The impact velocity of stony-iron impactors, according to the authors' calculations, can reach 12 km/s. The impact velocities of iron-nickel asteroids range from 6 to 9 km/s. The impactor's substance mass that could have remained in the crater after it was formed was assessed.

  7. Measurements of size-segregated emission particles by a sampling system based on the cascade impactor

    SciTech Connect

    Janja Tursic; Irena Grgic; Axel Berner; Jaroslav Skantar; Igor Cuhalev

    2008-02-01

    A special sampling system for measurements of size-segregated particles directly at the source of emission was designed and constructed. The central part of this system is a low-pressure cascade impactor with 10 collection stages for the size ranges between 15 nm and 16 {mu}m. Its capability and suitability was proven by sampling particles at the stack (100{sup o}C) of a coal-fired power station in Slovenia. These measurements showed very reasonable results in comparison with a commercial cascade impactor for PM10 and PM2.5 and with a plane device for total suspended particulate matter (TSP). The best agreement with the measurements made by a commercial impactor was found for concentrations of TSP above 10 mg m{sup -3}, i.e., the average PM2.5/PM10 ratios obtained by a commercial impactor and by our impactor were 0.78 and 0.80, respectively. Analysis of selected elements in size-segregated emission particles additionally confirmed the suitability of our system. The measurements showed that the mass size distributions were generally bimodal, with the most pronounced mass peak in the 1-2 {mu}m size range. The first results of elemental mass size distributions showed some distinctive differences in comparison to the most common ambient anthropogenic sources (i.e., traffic emissions). For example, trace elements, like Pb, Cd, As, and V, typically related to traffic emissions, are usually more abundant in particles less than 1 {mu}m in size, whereas in our specific case they were found at about 2 {mu}m. Thus, these mass size distributions can be used as a signature of this source. Simultaneous measurements of size-segregated particles at the source and in the surrounding environment can therefore significantly increase the sensitivity of the contribution of a specific source to the actual ambient concentrations. 25 refs., 3 figs., 2 tabs.

  8. Impact on thin steel plates by tumbling projectiles

    SciTech Connect

    Li, K.; Goldsmith, W.

    1995-12-31

    An experimental, analytical, and numerical investigation into the effects of tumbling projectiles on the impact response of thin 4130 steel target plates was performed. Deformation patterns and failure phenomena as well as the final velocities and trajectories of the projectiles are correlated with initial conditions such as the initial velocity and impact angle (or yaw angle with a zero oblique angle) of the projectile and plate thickness. In the experiments, tumbling motion of the projectiles was induced by impact of a portion of the front face of the projectile with the edge of a massive block placed along the trajectory. Cylinders with a diameter of 12.7 mm, a length of 38.1 mm, and a hardness of R{sub c} 54 were fired at velocities from 400 m/s - 800 m/s. The forward speed of the projectile after tumbling production ranged from 300 m/s-700 m/s. Rotational speeds ranged from 0 rad/s - 3000 rad/s and concomitant impact angles varied from 0{degrees} to 60{degrees}. These parameters were determined from high speed photographic records. The targets were 1.6 mm and 3.2 mm thick. An analytical model developed for thin aluminum target plates was employed in the present study. The model divides the penetration process into three stages: (1) plugging; (2) hole enlargement; and (3) frontal petaling. The processes are quantified using energy dissipation descriptions of the various deformation mechanisms. Numerical simulations of the penetration processes were performed by employment of the program DYNA3D, a nonlinear, three-dimensional finite element code. The material of the target was modeled as elasto-plastic with failure, while the projectile was assumed to be undeformable. The failure criterion of the target is based on the ultimate tensile strain.

  9. SIMS Studies of Allende Projectiles Fired into Stardust-type Aluminum Foils at 6 km/s

    NASA Technical Reports Server (NTRS)

    Hoppe, Peter; Stadermann, Frank J.; Stephan, Thomas; Floss, Christine; Leitner, Jan; Marhas, Kuljeet; Horz, Friedrich

    2006-01-01

    We have explored the feasibility of C-, N-, and O-isotopic measurements by NanoSIMS and of elemental abundance determinations by TOF-SIMS on residues of Allende projectiles that impacted Stardust-type aluminum foils in the laboratory at 6 km/s. These investigations are part of a consortium study aimed at providing the foundation for the characterization of matter associated with micro-craters that were produced during the encounter of the Stardust space probe with comet 81P/Wild 2. Eleven experimental impact craters were studied by NanoSIMS and eighteen by TOF-SIMS. Crater sizes were between 3 and 190 microns. The NanoSIMS measurements have shown that the crater morphology has only a minor effect on spatial resolution and on instrumental mass fractionation. The achievable spatial resolution is always better than 200 nm, and C- and O-isotopic ratios can be measured with a precision of several percent at a scale of several 100 nm, the typical size of presolar grains. This clearly demonstrates that presolar matter, provided it survives the impact into the aluminum foil partly intact, is recognizable even if embedded in material of Solar System origin. TOF-SIMS studies are restricted to materials from the crater rim. The element ratios of the major rockforming elements in the Allende projectiles are well characterized by the TOF-SIMS measurements, indicating that fractionation of those elements during impact can be expected to be negligible. This permits information on the type of impactor material to be obtained. For any more detailed assignments to specific chondrite groups, however, information on the abundances of the light elements, especially C, is crucial.

  10. Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Agbasi, Chijioke Raphael

    The non-linear elastodynamics of a flat plate subjected to low velocity foreign body impacts is studied, resembling the space debris impacts on the space structure. The work is based on a central hypothesis that in addition to identifying the impact locations, the material properties of the foreign objects can also be classified using acousto-ultrasonic signals (AUS). Simultaneous localization of impact point and classification of impact object is quite challenging using existing state-of-the-art structural health monitoring (SHM) approaches. Available techniques seek to report the exact location of impact on the structure, however, the reported information is likely to have errors from nonlinearity and variability in the AUS signals due to materials, geometry, boundary conditions, wave dispersion, environmental conditions, sensor and hardware calibration etc. It is found that the frequency and speed of the guided wave generated in the plate can be quantized based on the impactor's relationship with the plate (i.e. the wave speed and the impactor's mechanical properties are coupled). In this work, in order to characterize the impact location and mechanical properties of imapctors, nonlinear transient phenomenon is empirically studied to decouple the understanding using the dominant frequency band (DFB) and Lag Index (LI) of the acousto-ultrasonic signals. Next the understanding was correlated with the elastic modulus of the impactor to predict transmitted force histories. The proposed method presented in this thesis is especially applicable for SHM where sensors cannot be widely or randomly distributed. Thus a strategic organization and localization of the sensors is achieved by implementing the geometric configuration of Theodorous Spiral Sensor Cluster (TSSC). The performance of TSSC in characterizing the impactor types are compared with other conventional sensor clusters (e.g. square, circular, random etc.) and it is shown that the TSSC is advantageous over

  11. Effective dose scaling factors for use with cascade impactor sampling data in tenorm inhalation exposures.

    PubMed

    Kim, Kwang Pyo; Wu, Chang-Yu; Birky, Brian K; Bolch, Wesley E

    2005-10-01

    When assessing the effective dose to workers following radio-aerosol inhalation exposures, significant reductions in dose uncertainty can be achieved through direct measurement of the particle-size distribution. The University of Washington Mark III cascade impactor is one such air sampling device that permits the user to determine aerosol mass and radioactivity concentrations as a function of particle size within eight different size intervals (each corresponding to a different impactor stage or end filter). Traditionally, dose assessments made using the LUDEP code or other internal dosimetry software utilize this air sampling information by assigning the radioactivity measured at each stage as concentrated at a single representative size central to the size interval. In this study, we explore more realistic assumptions that the measured radioactivity distributes uniformly, linearly increases, or linearly decreases across the particle size interval for each impactor stage. The concept of an effective dose scaling factor, SF(E), is thus introduced whereby (1) the former approach can be used (which requires less computational effort using the LUDEP code), and (2) the resulting values of effective dose per stage can then be rescaled to values appropriate to a linear radioactivity distribution per stage. For a majority of (238)U-series radionuclides, particle size ranges, and absorption classes, differences in these two approaches are less than 10%, and thus no corrections in effective dose per particle stage are needed. Significant corrections, however, were noted in select cases. For uniform or linearly decreasing radioactivity distributions, end-filter particles (0.03 to 0.35 microm) of type F, M, or S radionuclides were assigned values of SF(E) ranging from 1.15 to 1.44, while 3(rd) stage particles (4.5 to 12 microm) of type M and S radionuclides were assigned values of SF(E) ranging from 1.11 to 1.53. When the cascade impactor measurements indicate a linear

  12. Effect of tubing deposition, breathing pattern, and temperature on aerosol mass distribution measured by cascade impactor.

    PubMed

    Gurses, Burak K; Smaldone, Gerald C

    2003-01-01

    Aerosols produced by nebulizers are often characterized on the bench using cascade impactors. We studied the effects of connecting tubing, breathing pattern, and temperature on mass-weighted aerodynamic particle size aerosol distributions (APSD) measured by cascade impaction. Our experimental setup consisted of a piston ventilator, low-flow (1.0 L/min) cascade impactor, two commercially available nebulizers that produced large and small particles, and two "T"-shaped tubes called "Tconnector(cascade)" and "Tconnector(nebulizer)" placed above the impactor and the nebulizer, respectively. Radiolabeled normal saline was nebulized using an airtank at 50 PSIG; APSD, mass balance, and Tconnector(cascade) deposition were measured with a gamma camera and radioisotope calibrator. Flow through the circuit was defined by the air tank (standing cloud, 10 L/min) with or without a piston pump, which superimposed a sinusoidal flow on the flow from the air tank (tidal volume and frequency of breathing). Experiments were performed at room temperature and in a cooled environment. With increasing tidal volume and frequency, smaller particles entered the cascade impactor (decreasing MMAD; e.g., Misty-Neb, 4.2 +/- 0.9 microm at lowest ventilation and 2.7 +/- 0.1 microm at highest, p = 0.042). These effects were reduced in magnitude for the nebulizer that produced smaller particles (AeroTech II, MMAD 1.8 +/- 0.1 to 1.3 +/- 0.1 microm; p = 0.0044). Deposition on Tconnector(cascade) increased with ventilation but was independent of cascade impactor flow. Imaging of the Tconnector(cascade) revealed a pattern of deposition unaffected by cascade impactor flow. These measurements suggest that changes in MMAD with ventilation were not artifacts of tubing deposition in the Tconnector(cascade). At lower temperatures, APSD distributions were more polydisperse. Our data suggest that, during patient inhalation, changes in particle distribution occur that are related to conditions in the tubing and

  13. Injury risk assessment of non-lethal projectile head impacts.

    PubMed

    Oukara, Amar; Nsiampa, Nestor; Robbe, Cyril; Papy, Alexandre

    2014-01-01

    Kinetic energy non-lethal projectiles are used to impart sufficient effect onto a person in order to deter uncivil or hazardous behavior with a low probability of permanent injury. Since their first use, real cases indicate that the injuries inflicted by such projectiles may be irreversible and sometimes lead to death, especially for the head impacts. Given the high velocities and the low masses involved in such impacts, the assessment approaches proposed in automotive crash tests and sports may not be appropriate. Therefore, there is a need of a specific approach to assess the lethality of these projectiles. In this framework, some recent research data referred in this article as "force wall approach" suggest the use of three lesional thresholds (unconsciousness, meningeal damages and bone damages) that depend on the intracranial pressure. Three corresponding critical impact forces are determined for a reference projectile. Based on the principle that equal rigid wall maximal impact forces will produce equal damage on the head, these limits can be determined for any other projectile. In order to validate the consistence of this innovative method, it is necessary to compare the results with other existing assessment methods. This paper proposes a comparison between the "force wall approach" and two different head models. The first one is a numerical model (Strasbourg University Finite Element Head Model-SUFEHM) from Strasbourg University; the second one is a mechanical surrogate (Ballistics Load Sensing Headform-BLSH) from Biokinetics. PMID:25400712

  14. Projectile Remnants in Central Peaks of Lunar Impact Craters

    NASA Astrophysics Data System (ADS)

    Johnson, B.; Yue, Z.; Minton, D.; Melosh, H. J.; Di, K.; Hu, W.; Liu, Y.

    2012-12-01

    It is generally assumed that during the formation of a large impact crater the projectile is largely melted or vaporized and that only traces remain in the final crater. However, using the finite difference hydrocode iSALE, we show that at impact velocities below about 12 km/sec the projectile, while crushed and strongly deformed, may largely survive the impact. In small craters the projectile is nevertheless widely dispersed across the crater floor. But in complex craters much of the projectile debris is swept back into the central peak area by the collapse flow. Furthermore, on the Moon approximately 30% of asteroid impacts occur at velocities less than 12 km/sec, so that the central peaks of many lunar craters should retain a recognizable signature of the projectile. This observation may explain recent observations of exotic Mg-rich spinels and olivine in the central peaks of craters too small to have excavated the deep crust or mantle of the Moon. Similar conclusions apply to central peaks of complex craters on Mars and Rheasilvia crater on Vesta.

  15. Injury Risk Assessment of Non-Lethal Projectile Head Impacts

    PubMed Central

    Oukara, Amar; Nsiampa, Nestor; Robbe, Cyril; Papy, Alexandre

    2014-01-01

    Kinetic energy non-lethal projectiles are used to impart sufficient effect onto a person in order to deter uncivil or hazardous behavior with a low probability of permanent injury. Since their first use, real cases indicate that the injuries inflicted by such projectiles may be irreversible and sometimes lead to death, especially for the head impacts. Given the high velocities and the low masses involved in such impacts, the assessment approaches proposed in automotive crash tests and sports may not be appropriate. Therefore, there is a need of a specific approach to assess the lethality of these projectiles. In this framework, some recent research data referred in this article as “force wall approach” suggest the use of three lesional thresholds (unconsciousness, meningeal damages and bone damages) that depend on the intracranial pressure. Three corresponding critical impact forces are determined for a reference projectile. Based on the principle that equal rigid wall maximal impact forces will produce equal damage on the head, these limits can be determined for any other projectile. In order to validate the consistence of this innovative method, it is necessary to compare the results with other existing assessment methods. This paper proposes a comparison between the “force wall approach” and two different head models. The first one is a numerical model (Strasbourg University Finite Element Head Model-SUFEHM) from Strasbourg University; the second one is a mechanical surrogate (Ballistics Load Sensing Headform-BLSH) from Biokinetics. PMID:25400712

  16. Influence of the projectiles' material in a coilgun

    NASA Astrophysics Data System (ADS)

    Hinaje, Melika; Netter, Denis

    2006-09-01

    A simple model of an electromagnetic launcher is introduced in this paper. The proposed model is an electrical one and is suitable for undergraduate students. The work consists of establishing an electrical model whose resolution gives the induced current and the speed of the projectile at a given inductor current and material projectile. In this manner by changing the material of the projectile we can deduce which one is the best. Then, a simple experiment illustrating the principles of a coilgun is described and some test results are given. Therefore, students learn electromagnetic phenomena through an electrical model which is simpler to study than a magnetic one. They have to solve a system of differential equations of the second order using numerical method. And finally, their theoretical study of the coilgun leads to an experimental bench.

  17. Safety and arming system for tube launched projectile

    NASA Astrophysics Data System (ADS)

    Chan, Steven N.

    1992-07-01

    An inertia element within a projectile is displaced to a retracted position by acceleration of the projectile during launch to unblock displacement of a slider to an armed position in response to subsequent pressurization of a projectile flight motor. Safe separation timers are thereby enabled in response to proper launch to delay pressurization of the flight motor and powering of an explosive firing circuit through switches actuated by said displacement of the slider from a safe position to the armed position. The slider is held in its safe position by an electrically grounded shear wire that is ruptured in response to slider displacement thereby removing a power disabling shunt connection to the firing circuit.

  18. Projectile Charge Effects in Differential Ionization by Positrons and Electrons

    SciTech Connect

    DuBois, R. D.; Gavin, J.; Lucio, O. G. de

    2009-03-10

    Differential data for single and double ionization of argon by positron and electron impact are presented and compared. For single ionization, coincidences between scattered projectiles, ejected electrons and recoil ions are measured as functions of the projectile scattering angle and energy loss. Differences associated with the sign of the projectile charge are indicated with regard to the scattering angle, the energy loss, and the relative intensities for binary and recoil events. Ejected electron-recoil ion coincidences are also measured as a function of the observation angle along the beam direction. From these, double to single ionization ratios are determined and compared. Differences in the magnitudes and angular dependences for positron and electron impact are attributed to the interference between the TS-1 and TS-2 double ionization mechanisms.

  19. Superconducting projectile for a rail gun and the combination of a rail gun with a superconducting projectile

    SciTech Connect

    Tidman, D.A.

    1990-02-20

    This patent describes a projectile for launching from a rail gun including first and second parallel, elongated electrically conducting metal rails insulated from each other and connected to opposite terminals of a DC power supply. The projectile comprising a forward portion, a rear portion, and an armature between the forward and rear portions, the rails and projectile armature being arranged so that current flows from one terminal of the power supply longitudinally of one of the rails thence through the projectile to the other rail thence longitudinally of the other rail back to the other terminal of the supply. The armature having multiple mutually insulated longitudinally extending superconductors arranged so that current flowing longitudinally in the rails from the power supply flows between the rails longitudinally through the superconductors with a component at right angles to the elongated direction of the rails. The superconductors being arranged, positioned and of a type that the current flowing longitudinally through them at right angles to and between the rails produces a force for driving the projectile longitudinally along the rails.

  20. Contaminant Interferences with SIMS Analyses of Microparticle Impactor Residues on LDEF Surfaces

    NASA Technical Reports Server (NTRS)

    Simon, C. G.; Batchelor, D.; Griffis, D. P.; Hunter, J. L.; Misra, V.; Ricks, D. A.; Wortman, J. J.

    1992-01-01

    Elemental analyses of impactor residues on high purity surface exposed to the low earth orbit (LEO) environment for 5.8 years on Long Duration Exposure Facility (LDEF) has revealed several probable sources for microparticles at this altitude, including natural micrometeorites and manmade debris ranging from paint pigments to bits of stainless steel. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences included pre-, post-, and in-flight deposited particulate surface contaminants, as well as indigenous heterogeneous material contaminants. Non-flight contaminants traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF and proximity to active electrical fields. In-flight deposited (low velocity) contaminants included urine droplets and bits of metal film from eroded thermal blankets.

  1. Mission Opportunities for the Flight Validation of the Kinetic Impactor Concept for Asteroid Deflection

    NASA Technical Reports Server (NTRS)

    Hernandez, Sonia; Barbee, Brent W.; Bhaskaran, Shyam; Getzandanner, Kenneth

    2013-01-01

    The kinetic impactor technique for deflecting near-Earth objects (NEOs), whereby a spacecraft is directed to collide with a NEO to alter its orbit via momentum transfer, is one of several proposed methods for defendingEarth against hazardous NEOs (asteroids and comets). In this paper we present detailed mission design concepts for a notionally feasible and aff ordable kinetic impactor flight validation mission deployed to a currently known near-Earth asteroid (NEA). Several filter steps are devised that utilize relevant criteria to optimally balance keyparameters, such as approach phase angle, estimated NEA diameter, relative velocity at intercept, and current NEA orbit knowledge, and produce refined lists of the most promising candidate target NEAs.

  2. Calibration of the QCM/SAW Cascade Impactor for Measurement of Ozone in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Wright, Cassandra K.; Sims, S. C.; Peterson, C. B.; Morris, V. R.

    1997-01-01

    The Quartz Crystal Microbalance Surface Acoustic Wave (QCM/SAW) cascade impactor collects size-fractionated distributions of aerosols on a series of 10 MHz quartz crystals and employs SAW devices coated with chemical sensors for gas detection. Presently, we are calibrating the ER-2 certified QCM/SAW cascade impactor in the laboratory for the detection of ozone. Experiments have been performed to characterize the QCM and SAW mass loading, saturation limits, mass frequency relationships, and sensitivity. We are also characterizing sampling efficiency by measuring the loss of ozone on different materials. There are parallel experiments underway to measure the variations in the sensitivity and response of the QCM/SAW crystals as a function of temperature and pressure. Results of the work to date will be shown.

  3. The Small Carry-on Impactor (SCI) and the Hayabusa2 Impact Experiment

    NASA Astrophysics Data System (ADS)

    Saiki, T.; Imamura, H.; Arakawa, M.; Wada, K.; Takagi, Y.; Hayakawa, M.; Shirai, K.; Yano, H.; Okamoto, C.

    2016-10-01

    Hayabusa2 is a sample return mission of JAXA launched on 3 December 2014. Hayabusa2 is the successor of Hayabusa, which returned samples from the asteroid Itokawa to the Earth. Although the design of Hayabusa2 follows that of Hayabusa, the former is equipped with some new components. The small carry-on impactor (SCI) is one of those components. The SCI is a compact kinetic impactor designed to remove the asteroid surface regolith locally and create an artificial crater. One of the most important scientific objectives of Hayabusa2 is to investigate the chemical and physical properties of the internal materials and structures of the target body, asteroid Ryugu. Hayabusa2 will attempt to observe the resultant crater with some scientific instruments and to get samples from around the crater. High kinetic energy is required to create a meaningful crater, however, the impact system design needs to fit within strict constraints. Complicated functions, such as a guidance and control system, are not permitted. A special type of shaped charge is used for the acceleration of the impactor of the SCI in order to make system simpler. Using this explosion technique makes it possible to accelerate the impactor very quickly and to hit the asteroid without a guidance system. However, the impact operation will be complicated because the explosive is very powerful and it scatters high-speed debris at the detonation. This paper describes an overview of the SCI system, the results of the development testing and an outline of the impact experiment of the Hayabusa2 mission.

  4. [Effect of impactor sampling on the ratio of respirable dust concentration to total dust concentration].

    PubMed

    Liu, G; Guo, W

    1998-11-30

    The aim of this study was to verify the change of the ratio of Respirable Dust Concentration (RDC) to Total Dust Concentration (TDC) taken by two-stage impactor sampling. The results showed that there was a correlation between the ratio of RDC/TDC and TDC (correlation coefficient was 0.8576, 0.8689, 0.8736 and 0.9674, respectively) under the condition of identical sampling volume, and the ratio increases along with the elevated TDC.

  5. Numerical simulation of fluid flow around a scramaccelerator projectile

    NASA Technical Reports Server (NTRS)

    Pepper, Darrell W.; Humphrey, Joseph W.; Sobota, Thomas H.

    1991-01-01

    Numerical simulations of the fluid motion and temperature distribution around a 'scramaccelerator' projectile are obtained for Mach numbers in the 5-10 range. A finite element method is used to solve the equations of motion for inviscid and viscous two-dimensional or axisymmetric compressible flow. The time-dependent equations are solved explicitly, using bilinear isoparametric quadrilateral elements, mass lumping, and a shock-capturing Petrov-Galerkin formulation. Computed results indicate that maintaining on-design performance for controlling and stabilizing oblique detonation waves is critically dependent on projectile shape and Mach number.

  6. Properties of original impactors estimated from three-dimensional analysis of whole Stardust tracks

    SciTech Connect

    Greenberg, Michael; Ebel, Denton S.

    2012-07-25

    The Stardust mission captured comet Wild 2 particles in aerogel at 6.1 km s{sup -1}. We performed high-resolution three-dimensional imaging and X-ray fluorescence mapping of whole cometary tracks in aerogel. We present the results of a survey of track structures using laser scanning confocal microscopy, including measurements of track volumes, entry hole size, and cross-sectional profiles. We compare various methods for measuring track parameters. We demonstrate a methodology for discerning hypervelocity particle ablation rates using synchrotron-based X-ray fluorescence, combined with mass and volume estimates of original impactors derived from measured track properties. Finally, we present a rough framework for reconstruction of original impactor size, and volume of volatilized material, using our measured parameters. The bulk of this work is in direct support of nondestructive analysis and identification of cometary grains in whole tracks, and its eventual application to the reconstruction of the size, shape, porosity, and chemical composition of whole Stardust impactors.

  7. Simulation on a novel micron-array inertial impactor for submicron and ultrafine particle separation

    NASA Astrophysics Data System (ADS)

    Liu, Rui-Tao; Tao, Lu-Qi; Yang, Yi; Ren, Tian-Ling

    2016-08-01

    The particulate matter (PM), which was put forward in 1997 by US, had taken more and more attention due to the influence on human health. Although the mass concentration, number concentration and chemical composition of PM were still major research directions, how to collect these PMs more efficiently becomes critical. Inertial impactor is an effective separation device, however, due to different motion states of PM2.5 and PM0.3 in the flow field, the inertial impactor which can separate PM0.3 from other PMs has not been fabricated. In this work, the motion states for both submicron and ultrafine particles were studied by using classical theory of channel aerodynamic, and a novel micron-array inertial impactor was designed and simulated for the first time. Besides, the influence of some characteristic parameters (W, T, S, Dc, etc.) on particle collection efficiency were researched and discussed through simulation results. This novel structure can be easily fabricated by MEMS technology or laser direct writing and also can be widely used in particle separation or flexible sensor fields.

  8. Spherule layers, crater scaling laws, and the population of ancient terrestrial impactors

    NASA Astrophysics Data System (ADS)

    Johnson, Brandon C.; Collins, Gareth S.; Minton, David A.; Bowling, Timothy J.; Simonson, Bruce M.; Zuber, Maria T.

    2016-06-01

    Ancient layers of impact spherules provide a record of Earth's early bombardment history. Here, we compare different bombardment histories to the spherule layer record and show that 3.2-3.5 Ga the flux of large impactors (10-100 km in diameter) was likely 20-40 times higher than today. The E-belt model of early Solar System dynamics suggests that an increased impactor flux during the Archean is the result of the destabilization of an inward extension of the main asteroid belt (Bottke et al., 2012). Here, we find that the nominal flux predicted by the E-belt model is 7-19 times too low to explain the spherule layer record. Moreover, rather than making most lunar basins younger than 4.1 Gyr old, the nominal E-belt model, coupled with a corrected crater diameter scaling law, only produces two lunar basins larger than 300 km in diameter. We also show that the spherule layer record when coupled with the lunar cratering record and careful consideration of crater scaling laws can constrain the size distribution of ancient terrestrial impactors. The preferred population is main-belt-like up to ∼50 km in diameter transitioning to a steep distribution going to larger sizes.

  9. Problems associated with launching hypervelocity projectiles from the Fast Shock Tube

    SciTech Connect

    Kerrisk, J.F.; Meier, J.K.

    1992-01-01

    Modeling and experiments are being done with the goal of understanding the physics of projectile acceleration at high driving pressures (megabar range) and short acceleration times (a few microseconds) well enough to design and test successful hypervelocity launch systems. The Fast Shock Tube, a cylindrically convergent high-explosive driver, has been used to accelerate projectiles. Detailed modeling of the experiments, including high-pressure gas flow, projectile instability, and projectile fracture, has been done with MESA/2D. Modeling results show quantitative agreement with the average behavior of the system. However, details of projectile behavior are not predicted well. Observed velocity distributions across the diameter of a projectile or projectile shapes are only in qualitative agreement with calculations. This, then, presents the major constraint on the successful design of a launch system: that the processes that limit projectile integrity depend on the details of the drive conditions, and these details are not quantitatively modeled at this time.

  10. Problems associated with launching hypervelocity projectiles from the Fast Shock Tube

    SciTech Connect

    Kerrisk, J.F.; Meier, J.K.

    1992-07-01

    Modeling and experiments are being done with the goal of understanding the physics of projectile acceleration at high driving pressures (megabar range) and short acceleration times (a few microseconds) well enough to design and test successful hypervelocity launch systems. The Fast Shock Tube, a cylindrically convergent high-explosive driver, has been used to accelerate projectiles. Detailed modeling of the experiments, including high-pressure gas flow, projectile instability, and projectile fracture, has been done with MESA/2D. Modeling results show quantitative agreement with the average behavior of the system. However, details of projectile behavior are not predicted well. Observed velocity distributions across the diameter of a projectile or projectile shapes are only in qualitative agreement with calculations. This, then, presents the major constraint on the successful design of a launch system: that the processes that limit projectile integrity depend on the details of the drive conditions, and these details are not quantitatively modeled at this time.

  11. 78. PHOTO OF A PROJECTILE FIRING USING A SABOT TAKEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    78. PHOTO OF A PROJECTILE FIRING USING A SABOT TAKEN WITH A 70 MM MITCHEL MOTION PICTURE CAMERA, Date unknown, circa 1950. (Original photograph in possession of Dave Willis, San Diego, California.) Photograph represents central frame of negative. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  12. Projectile General Motion in a Vacuum and a Spreadsheet Simulation

    ERIC Educational Resources Information Center

    Benacka, Jan

    2015-01-01

    This paper gives the solution and analysis of projectile motion in a vacuum if the launch and impact heights are not equal. Formulas for the maximum horizontal range and the corresponding angle are derived. An Excel application that simulates the motion is also presented, and the result of an experiment in which 38 secondary school students…

  13. Projectile Motion in the "Language" of Orbital Motion

    ERIC Educational Resources Information Center

    Zurcher, Ulrich

    2011-01-01

    We consider the orbit of projectiles launched with arbitrary speeds from the Earth's surface. This is a generalization of Newton's discussion about the transition from parabolic to circular orbits, when the launch speed approaches the value [image omitted]. We find the range for arbitrary launch speeds and angles, and calculate the eccentricity of…

  14. Projectile deformation effects in the breakup of 37Mg

    NASA Astrophysics Data System (ADS)

    Shubhchintak; Chatterjee, R.; Shyam, R.

    2016-05-01

    We study the breakup of 37Mg on Pb at 244MeV/u with the recently developed extended theory of Coulomb breakup within the postform finite range distorted wave Born approximation that includes deformation of the projectile. Comparing our calculated cross section with the available Coulomb breakup data we determine the possible ground state configuration of 37Mg.

  15. Apparatus for Teaching Physics: A Versatile Projectile Motion Board.

    ERIC Educational Resources Information Center

    Prigo, Robert B.; Korda, Anthony

    1984-01-01

    Describes the design and use of a projectile motion apparatus to illustrate a variety of projective motion results typically discussed in an introductory course. They include independence of horizontal (constant speed) and vertical (constant acceleration) motions, parabolic path shape, and other types of motion. (JN)

  16. Projectile attitude and position determination using magnetometer sensor only

    NASA Astrophysics Data System (ADS)

    Changey, Sebastien; Fleck, Volker; Beauvois, Dominique

    2005-03-01

    A priori information given by the complete modelling of the ballistic behavior (trajectory, attitude) of the projectile is simplified to give a pertinent reduced evolution model. An algorithm based on extended Kalman filters is designed to determinate: " position: x,y,z references in earth frame. " value and direction of the velocity vector; its direction is given by 2 angles (η and θ). " attitude around velocity vector given by 3 angles: roll angle in the range [0, 2π], angle of attack α and side-slip angle β in the range of few milliradians. The estimation is based on the measures of the magnetic field of the earth given by a three-axis magnetometer sensor embedded on the projectile. The algorithm also needs the knowledge of the direction of the earth magnetic fields in the earth frame and aerodynamics coefficients of the projectile. The algorithm has been tested on simulation, using real evolution of attitude data for a shot with a 155 mm rotating projectile over a distance of 16 km, with wind and measurement noise. The results show that we can estimate milliradians with non-linear equations and approximations, with good precision.

  17. On the Trajectories of Projectiles Depicted in Early Ballistic Woodcuts

    ERIC Educational Resources Information Center

    Stewart, Sean M.

    2012-01-01

    Motivated by quaint woodcut depictions often found in many late 16th and 17th century ballistic manuals of cannonballs fired in air, a comparison of their shapes with those calculated for the classic case of a projectile moving in a linear resisting medium is made. In considering the asymmetrical nature of such trajectories, the initial launch…

  18. Characterization of Concrete Material Flow During Projectile Penetration

    NASA Astrophysics Data System (ADS)

    Sobeski, Robert

    The Department of Defense (DoD) has an operational requirement to predict, quickly and accurately, the depth of penetration that a projectile can achieve for a given target and impact scenario. Fast-running analytical models can provide reliable predictions, but they often require the use of one or more dimensionless parameters that are derived from experimental data. These analytical models are continually evolving, and the dimensionless parameters are often adjusted to obtain new analytical models without a true understanding of the change in characteristics of material flow across targets of varying strength and projectile impact velocities. In this dissertation, the penetration of ogive-nose projectiles into concrete targets is investigated using finite element analyses. The Elastic-Plastic Impact Computation (EPIC) code is used to examine the velocity vector fields and their associated direction cosines for high and low-strength concrete target materials during projectile penetration. Two methodologies, referred as Normal Expansion Comparison Methodology (NECM) and Spherical Expansion Comparison Methodology (SECM), are developed in MATLAB to quantify the change in concrete material flow during this short-duration dynamic event. Improved velocity profiles are proposed for better characterization of cavity expansion stresses based on the application of NECM and SECM to EPIC outputs. Structural engineers and model developers working on improving the accuracy of current analytical concrete penetration models and potentially reducing their reliance on fitting parameters will benefit from the findings of this research.

  19. The Long Decay Model of One-Dimensional Projectile Motion

    ERIC Educational Resources Information Center

    Lattery, Mark Joseph

    2008-01-01

    This article introduces a research study on student model formation and development in introductory mechanics. As a point of entry, I present a detailed analysis of the Long Decay Model of one-dimensional projectile motion. This model has been articulated by Galileo ("in De Motu") and by contemporary students. Implications for instruction are…

  20. 22. VAL, VIEW OF PROJECTILE LOADING DECK LOOKING NORTHEAST TOWARD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. VAL, VIEW OF PROJECTILE LOADING DECK LOOKING NORTHEAST TOWARD TOP OF CONCRETE 'A' FRAME STRUCTURE SHOWING DRIVE CABLES, DRIVE GEAR, BOTTOM OF CAMERA TOWER AND 'CROWS NEST' CONTROL ROOM. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  1. 73. DETAIL OF 'A' FRAME STRUCTURE LOOKING NORTH SHOWING PROJECTILE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    73. DETAIL OF 'A' FRAME STRUCTURE LOOKING NORTH SHOWING PROJECTILE CAR, CAMERA TOWER, CANTILEVERED WALKWAYS AND ELECTRICAL GEAR, August 17, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  2. Projectile - Mass asymmetry systematics for low energy incomplete fusion

    NASA Astrophysics Data System (ADS)

    Singh, Pushpendra P.; Yadav, Abhishek; Sharma, Vijay R.; Sharma, Manoj K.; Kumar, Pawan; Sahoo, Rudra N.; Kumar, R.; Singh, R. P.; Muralithar, S.; Singh, B. P.; Bhowmik, R. K.; Prasad, R.

    2015-06-01

    In the present work, low energy incomplete fusion (ICF) in which only a part of projectile fuses with target nucleus has been investigated in terms of various entrance channel parameters. The ICF strength function has been extracted from the analysis of experimental excitation functions (EFs) measured for different projectile-target combinations from near- to well above- barrier energies in 12C,16O(from 1.02Vb to 1.64Vb)+169Tm systems. Experimental EFs have been analysed in the framework statistical model code PACE4 based on the idea of equilibrated compound nucleus decay. It has been found that the value of ICF fraction (FICF) increases with incident projectile energy. A substantial fraction of ICF (FICF ≈ 7 %) has been accounted even at energy as low as ≈ 7.5% above the barrier (at relative velocity νrel ≈0.027) in 12C+169Tm system, and FICF ≈ 10 % at νrel ≈0.014 in 16O+169Tm system. The probability of ICF is discussed in light of the Morgenstern's mass-asymmetry systematics. The value of FICF for 16O+169Tm systems is found to be 18.3 % higher than that observed for 12C+169Tm systems. Present results together with the re-analysis of existing data for nearby systems conclusively demonstrate strong competition of ICF with CF even at slightly above barrier energies, and strong projectile dependence that seems to supplement the Morgenstern's systematics.

  3. Momentum distributions of isotopes produced by fragmentation of relativistic C-12 and O-16 projectiles

    NASA Technical Reports Server (NTRS)

    Greiner, D. E.; Lindstrom, P. J.; Heckman, H. H.; Cork, B.; Bieser, F. S.

    1975-01-01

    The fragment momentum distributions in the projectile rest frame are, typically, Gaussian shaped, narrow, consistent with isotropy, depend on fragment and projectile, and have no significant correlation with target mass or beam energy. The nuclear temperature is inferred from the momentum distributions of the fragments and is approximately equal to the projectile nuclear binding energy, indicative of small energy transfer between target and fragment.

  4. Diverse impactors in Apollo 15 and 16 impact melt rocks: Evidence from osmium isotopes and highly siderophile elements

    NASA Astrophysics Data System (ADS)

    Liu, Jingao; Sharp, Miriam; Ash, Richard D.; Kring, David A.; Walker, Richard J.

    2015-04-01

    Concentrations of highly siderophile elements (HSE) and 187Os/188Os isotopic compositions for eleven impact related rocks from the Apollo 15 and 16 landing sites are reported and combined with existing geochronological data to investigate the chemical nature and temporal changes in the large impactors implicated in the formation of the lunar basins. Data for the samples all define linear trends on plots of HSE versus Ir concentrations, whose slopes likely reflect the relative HSE compositions of the dominant impactors that formed the rocks. The inferred Imbrium basin impactor that generated Apollo 15 impact melt rocks 15445 and 15455 was characterized by modestly suprachondritic 187Os/188Os, Ru/Ir, Pt/Ir and Pd/Ir ratios. Diverse impactor components are revealed in the Apollo 16 impact melt rocks. The 187Os/188Os and HSE/Ir ratios of the impactor components in melt rocks 60635, 63595 and 68416, with reported ages <3.84 Ga, are within the range of chondritic meteorites, but slightly higher than ratios characterizing previously studied granulitic impactites with reported ages >4.0 Ga. By contrast, the impactor components in melt rocks 60235, 62295 and 67095, with reported ages of ∼3.9 Ga, are characterized by suprachondritic 187Os/188Os and HSE/Ir ratios similar to the Apollo 15 impact melt rocks, and may also sample the Imbrium impactor. Three lithic clasts from regolith breccias 60016 and 65095, also with ∼3.9 Ga ages, contain multiple impactor components, of which the dominant composition is considerably more suprachondritic than those implicated for Imbrium and Serenitatis (Apollo 17) impactors. The dominant composition recorded in these rocks was most likely inherited from a pre-Imbrium impactor. Consideration of composition versus age relations among lunar impact melt rocks reveals no discernable trend. Virtually all lunar impact melt rocks sampled by the Apollo missions, as well as meteorites, are characterized by 187Os/188Os and HSE/Ir ratios that, when

  5. Evidence for electron-electron interaction in projectile K -shell ionization

    SciTech Connect

    Hulskotter, H.; Meyerhof, W.E.; Dillard, E.; Guardala, N. )

    1989-10-30

    Cross sections for projectile {ital K}-shell ionization were measured for 0.75--3.5-MeV/{ital N} C{sup 5+} and O{sup 7+} projectiles in collisions with H{sub 2} and He targets. The experimental results agree with plane-wave Born-approximation calculations which take into account the interaction between projectile and target electrons. We demonstrate that for energies where the target electrons have sufficient kinetic energy in the projectile frame to ionize the projectile electron, the electron-electron interaction can lead to a significant increase in the total ionization cross section.

  6. Rebuttal to the comment by Malhotra and Strom on "Constraints on the source of lunar cataclysm impactors"

    NASA Astrophysics Data System (ADS)

    Ćuk, Matija; Gladman, Brett J.; Stewart, Sarah T.

    2011-11-01

    Ćuk et al. (Ćuk, M. Gladman, B.J., Stewart, S.T. [2010]. Icarus 207 590-594) concluded that the the lunar cataclysm (late heavy bombardment) was recorded in lunar Imbrian era craters, and that their size distribution is different from that of main belt asteroids (which may have been the dominant pre-Imbrian impactors). This result would likely preclude the asteroid belt as the direct source of lunar cataclysm impactors. Malhotra and Strom (Malhotra, R., Strom, R.G. [2011]. Icarus) maintain that the lunar impactor population in the Imbrian era was the same as in Nectarian and pre-Nectarian periods, and this population had a size distribution identical to that of main belt asteroids. In support of this claim, they present an Imbrian size distribution made from two data sets published by Wilhelms et al. (Wilhelms, D.E., Oberbeck, V.R., Aggarwal, H.R. [1978]. Proc. Lunar Sci. Conf. 9, 3735-3762). However, these two data sets cannot be simply combined as they represent areas of different ages and therefore crater densities. Malhotra and Strom (Malhotra, R., Strom, R.G. [2011]. Icarus) differ with the main conclusion of Wilhelms et al. (Wilhelms, D.E., Oberbeck, V.R., Aggarwal, H.R. [1978]. Proc. Lunar Sci. Conf. 9, 3735-3762) that the Nectarian and Imbrian crater size distributions were different. We conclude that the available data indicate that the lunar Imbrian-era impactors had a different size distribution from the older ones, with the Imbrian impactor distribution being significantly richer in small impactors than that of older lunar impactors or current main-belt asteroids.

  7. Mixing of Impactor Liquid Cores and Planetesimals Constrained by Single Silicate Crystal Magnetism

    NASA Astrophysics Data System (ADS)

    Bono, R. K.; Tarduno, J. A.; Nimmo, F.; Scott, E.; Ferrière, L.

    2014-12-01

    The formation of pallasites, meteorites composed mainly of intermixed FeNi metal and angular to rounded olivine crystals, has been a paradox because these components should have separated into distinct layers at their putative location of origin: the core-mantle boundary (CMB) of an asteroid. Paleomagnetic study of gem-like angular olivine bearing minute magnetic inclusions from the main group Esquel and Imilac pallasite meteorites, however, reveals the past presence of strong magnetic fields requiring a core dynamo. A CMB location is too hot for pallasites to record these magnetizations. Alternatively, the paleomagnetic field strengths, combined with cooling rate data and thermal modeling, suggest an origin for main group pallasites in the shallow mantle of a parent body, with the FeNi metal originating from the liquid core of an impactor (Tarduno et al., Science, 2012). Here, we extend this model to include the origin of main group pallasite meteorites with rounded olivine, and pallasites of the Eagle Station group. Main group pallasites with rounded olivine (e.g., Springwater) could have formed in larger intruded liquid FeNi masses relative to the thinner dikes envisioned for the formation of pallasites with angular olivine crystals. Pallasites of the Eagle Station group have an oxygen isotope composition different from that of the main group and thus require a separate parent body. Olivine from the Eagle Station pallasite also carries a paleomagnetic record; therefore pallasites from this group may have also formed by collision. Interestingly, the magnetization of the Eagle Station pallasite is multi-component and distinctly different from the main group. This signal potentially records a combination of a dynamo signal and a later shock heating event. Mesosiderites may represent a third parent body formed by impactor liquid FeNi metal injected into the crust of an asteroid. These observations suggest liquid metal intrusion from differentiated impactors may have

  8. A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors.

    PubMed

    Brown, P G; Assink, J D; Astiz, L; Blaauw, R; Boslough, M B; Borovička, J; Brachet, N; Brown, D; Campbell-Brown, M; Ceranna, L; Cooke, W; de Groot-Hedlin, C; Drob, D P; Edwards, W; Evers, L G; Garces, M; Gill, J; Hedlin, M; Kingery, A; Laske, G; Le Pichon, A; Mialle, P; Moser, D E; Saffer, A; Silber, E; Smets, P; Spalding, R E; Spurný, P; Tagliaferri, E; Uren, D; Weryk, R J; Whitaker, R; Krzeminski, Z

    2013-11-14

    Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (±100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×10(12) joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes. PMID:24196713

  9. Reduction of nitrate losses from filter and impactor samplers by means of concentration enrichment

    NASA Astrophysics Data System (ADS)

    Chang, Ming Chih; Sioutas, Constantinos; Kim, Seongheon; Gong, Henry; Linn, William S.

    Sampling errors (artifacts) have greatly affected the precision of the quantitative analysis of volatile species, such as particulate ammonium nitrate. This work presents the effect of the enrichment in concentration of particulate nitrate in reducing volatilization losses in impactors and Teflon filter samplers. During the performance characterization of an ambient fine particle concentrator developed by Sioutas et al. (1995a, Environmental Health Perspectives 103, 172-177, 1995b, Inhalation Toxicology, 7, 633-644, 1977, Journal of Aerosol Science 28, 1057-1071) losses of ambient ammonium nitrate from denuded and undenuded Teflon filter samplers as well as the microorifice uniform deposit impactor (MOUDI) were evaluated in Los Angeles, CA, an area where ammonium nitrate constitutes a major component of ambient fine particulate matter. The field study data were compared to those predicted theoretically for a given set of gas and particulate nitrate concentrations, temperature and relative humidity. Both theoretical and experimental results indicated that the ratio of nitrate gas-to-particle concentration affects significantly the volatilization loss, with higher volatilization losses occurring at higher gas-to-particle concentration values. The concentration enrichment of particulate-phase nitrate resulted in reducing evaporation losses from the MOUDI from 20-50% to less than 10%. Losses of nitrate from denuded Teflon filters were reduced from 60-95% to less than 30%, and for undenuded Teflon filters from 30-80% to less than 5%. Our study concluded that nitrate losses from impactor, denuded and undenuded Teflon filter samplers could be virtually eliminated by placing the sampler downstream of a particle concentrator with a small cutpoint (i.e., 0.1 μm).

  10. A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

    NASA Astrophysics Data System (ADS)

    Brown, P. G.; Assink, J. D.; Astiz, L.; Blaauw, R.; Boslough, M. B.; Borovička, J.; Brachet, N.; Brown, D.; Campbell-Brown, M.; Ceranna, L.; Cooke, W.; de Groot-Hedlin, C.; Drob, D. P.; Edwards, W.; Evers, L. G.; Garces, M.; Gill, J.; Hedlin, M.; Kingery, A.; Laske, G.; Le Pichon, A.; Mialle, P.; Moser, D. E.; Saffer, A.; Silber, E.; Smets, P.; Spalding, R. E.; Spurný, P.; Tagliaferri, E.; Uren, D.; Weryk, R. J.; Whitaker, R.; Krzeminski, Z.

    2013-11-01

    Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (+/-100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×1012 joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes.

  11. Surveying the South Pole-Aitken basin magnetic anomaly for remnant impactor metallic iron

    USGS Publications Warehouse

    Cahill, Joshua T.S.; Hagerty, Justin J.; Lawrence, David M.; Klima, Rachel L.; Blewett, David T.

    2014-01-01

    The Moon has areas of magnetized crust ("magnetic anomalies"), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.

  12. Simultaneous PVDF/VISAR measurement technique for isentropic loading with graded density impactors

    SciTech Connect

    Anderson, M.U.; Chhabildas, L.C.; Reinhart, W.D.

    1997-10-01

    A simultaneous PVDF/VISAR measurement technique was used for isentropic-loading experiments with a polymethyl methacrylate (PMMA) specimen. The experiments used a graded density impactor accelerated onto a tantalum driver backed with PMMA and then lithium fluoride windows for each experiment. Simultaneous measurements made at each window interface provided precise transit time and particle velocity measurements which can be used to determine the stress-vs-strain loading path using Lagrangian analysis techniques. The experimental technique provides access to 40 GPa stress levels in PMMA under isentropic-loading conditions.

  13. Phenomenological Investigation of Rapid Projectile Penetration in Granular Media

    NASA Astrophysics Data System (ADS)

    Omidvar, Mehdi

    There has been a recent flurry of research in rapid penetration into granular media, motivated by military and civilian applications including underground target penetration, design of fortifications, drilling for resource extraction, offshore foundations and anchors, probing of in situ mechanical properties, and study of high strain rate response of granular media, among others. The present study contributes to the state of the art in rapid penetration into granular media, by producing data at the macro and meso scales. In-house projectile accelerators are used to launch projectiles into laboratory scale physical models. The experimental program is divided into two sections. In the first section, penetration tests are performed at impact velocities in the range of 60-300 m/s. High-speed imaging and photonic Doppler velocimetry are used to record time history of penetration. In the second section, low velocity penetration tests are performed in refractive index matched transparent soils. Images are acquired form a mid plane within the sample. Digital image correlation is employed to describe granular kinematics. Macro scale test results point to the existence of at least two transition regimes in penetration resistance. The first, occurring at penetration velocities of approximately 60- 80 m/s, may be due the role of particle crushing, while the second is linked to frictional resistance dominating over inertial resistance at penetration velocities below approximately 15 m/s. It is also found that the role of nose shape is related to particle crushing. An attached false cone forms ahead of the projectile due to significant particle crushing, rendering nose shape effects less significant. Packing density and saturation are also found to affect penetration characteristics. Penetration tests in transparent soils reveal significant differences between quasi-static and dynamic penetration. Greater vertical displacements occur ahead of the projectile in dynamic

  14. The development of a cascade impactor simulator based on adhesion force measurements to aid the development of dry powder inhalations.

    PubMed

    Podczeck, F

    1997-05-01

    Adhesion and friction forces are the main physical factors determining the re-suspension of a micronized drug from carrier particles during inhalation. Hence, it appears useful to link adhesion and friction force measurements to the in vitro testing of dry powder inhalations, namely the assessment of the mass median aerodynamic diameter (MMAD) using an eight-stage Andersen cascade impactor. Interactive mixtures of micronized Salmeterol Xinafoate adhered to irrespirable lactose monohydrate carrier particles were used as model dosage forms. The adhesion force between the drug and carrier particles was assessed using a centrifuge technique, and the MMAD was determined under standardized working conditions using the Andersen-Cascade impactor (Mark II). A cascade impactor simulator (CIS), which is a computer program containing a re-suspension model to assess the amount of drug detached from the carrier particles during inhalation, was developed and validated using the experimental data. It could be shown, that the CIS provided a good estimate of the loss of drug due to adhesion to the carrier particles and the loss of drug on the cascade impactor walls. Small deviations between the theoretical and experimental mass median aerodynamic particle diameters however were found. These deviations were shown to be mainly due to the experimental error introduced by the cascade impactor, and that the error due to the experimental adhesion measurements is negligibly small. Hence, the CIS developed could be a useful tool in early development stages of dry powder inhalations to predict the in vitro aerodynamic performance of drug particles.

  15. Cascade impactor (CI) mensuration--an assessment of the accuracy and precision of commercially available optical measurement systems.

    PubMed

    Chambers, Frank; Ali, Aziz; Mitchell, Jolyon; Shelton, Christopher; Nichols, Steve

    2010-03-01

    Multi-stage cascade impactors (CIs) are the preferred measurement technique for characterizing the aerodynamic particle size distribution of an inhalable aerosol. Stage mensuration is the recommended pharmacopeial method for monitoring CI "fitness for purpose" within a GxP environment. The Impactor Sub-Team of the European Pharmaceutical Aerosol Group has undertaken an inter-laboratory study to assess both the precision and accuracy of a range of makes and models of instruments currently used for optical inspection of impactor stages. Measurement of two Andersen 8-stage 'non-viable' cascade impactor "reference" stages that were representative of jet sizes for this instrument type (stages 2 and 7) confirmed that all instruments evaluated were capable of reproducible jet measurement, with the overall capability being within the current pharmacopeial stage specifications for both stages. In the assessment of absolute accuracy, small, but consistent differences (ca. 0.6% of the certified value) observed between 'dots' and 'spots' of a calibrated chromium-plated reticule were observed, most likely the result of treatment of partially lit pixels along the circumference of this calibration standard. Measurements of three certified ring gauges, the smallest having a nominal diameter of 1.0 mm, were consistent with the observation where treatment of partially illuminated pixels at the periphery of the projected image can result in undersizing. However, the bias was less than 1% of the certified diameter. The optical inspection instruments evaluated are fully capable of confirming cascade impactor suitability in accordance with pharmacopeial practice.

  16. Response of laminated composite plates to low-speed impact by airgun-propelled and dropped-weight impactors

    NASA Technical Reports Server (NTRS)

    Prasad, Chunchu B.; Ambur, Damodar R.; Starnes, James H., Jr.

    1993-01-01

    An analytical procedure has been developed to determine the transient response of simply supported, rectangular laminated composite plates subjected to impact loads from airgun-propelled or dropped-weight impactors. A first-order shear-deformation theory has been included in the analysis to represent properly any local short-wavelength transient bending response. The impact force has been modeled as a locally distributed load with a cosine-cosine distribution. A double Fourier series expansion and the Timoshenko small increment method have been used to determine the contact force, out-of-plane deflections, and inplane strains and stresses at any plate location due to an impact force at any plate location. The results of experimental and analytical studies are compared for quasi-isotropic laminates. The results indicate the importance of including transverse shear deformation effects in the analysis for predicting the response of laminated plates subjected to both airgun-propelled and dropped-weight impactors. The results also indicate that plate boundary conditions influence the axial strains more significantly than the contact force for a dropped-weight impactor. The results of parametric studies identify a scaling approach based on impactor momentum that suggests an explanation for the differences in the responses of plates impacted by airgun-propelled or dropped-weight impactors.

  17. Investigation of shock-induced combustion past blunt projectiles

    NASA Technical Reports Server (NTRS)

    Ahuja, J. K.; Tiwari, S. N.

    1996-01-01

    A numerical study is conducted to simulate shock-induced combustion in premixed hydrogen-air mixtures at various free-stream conditions and parameters. Two-dimensional axisymmetric, reacting viscous flow over blunt projectiles is computed to study shock-induced combustion at Mach 5.11 and Mach 6.46 in hydrogen-air mixture. A seven-species, seven reactions finite rate hydrogen-air chemical reaction mechanism is used combined with a finite-difference, shock-fitting method to solve the complete set of Navier-Stokes and species conservation equations. The study has allowed an improved understanding of the physics of shock-induced combustion over blunt projectiles and the numerical results can now be explained more readily with one-dimensional wave-interaction model.

  18. Performance of the Projectile Fragmentation Wall at CELSIUS Storage Ring

    NASA Astrophysics Data System (ADS)

    Siwek, A.; Budzanowski, A.; Czech, B.; Gburek, T.; Jakobsson, B.; Kozik, E.; Skwirczyńska, I.; Westerberg, L.

    The projectile fragmentation wall [Budzanowski, A. et al., Nucl. Instr. Meth. A482, 528 (2002).] (PFW) is a part of a bigger detection system comprising of the CHICSi detector [Jakobsson, B., Nucl. Phys. News Int. 9:2, 22 (1999). Siwek, A., Nucl. Phys., A654, 2695 (1999)] and a recoil detectors array [Kuznetsov, A. V. et al, Nucl. Instr. Meth. A452, 525 (2000)]. The system is designed to register products of proton- and heavy ion-induced reactions at the energies 50-450 MeV/nucleon (see Bo Jakobsson's contribution to this conference). The aim of PFW is to register and identify projectile like fragments emitted in forward direction not covered by the CHICSi detector.

  19. Ballistics considerations for small-caliber, low-density projectiles

    SciTech Connect

    Gouge, M.J.; Baylor, L.R.; Combs, S.K.; Fisher, P.W.; Foster, C.A.; Foust, C.R.; Milora, S.L.; Qualls, A.L.

    1993-11-01

    One major application for single- and two-stage light gas guns is for fueling magnetic fusion confinement devices. Powder guns are not a feasible alternative due to possible plasma contamination by residual powder gases and the eventual requirement of steady-state operation at {approximately} 1 Hz, which will dictate a closed gas handling system where propellant gases are recovered, processed and recompressed. Interior ballistic calculations for single-stage light gas guns, both analytical and numerical, are compared to an extensive data base for low density hydrogenic projectiles (pellets). Some innovative range diagnostics are described for determining the size and velocity of these small (several mm) size projectiles. A conceptual design of a closed cycle propellant gas system is presented including tradeoffs between different light propellant gases.

  20. Computational and Experimental Investigations of Turbulent Flow Past Projectiles

    NASA Astrophysics Data System (ADS)

    Mehmedagic, Igbal; Carlucci, Pasquale; Carlucci, Donald; Thangam, Siva

    2008-11-01

    Experimental and computational investigations of turbulent flow past projectiles is modeled as axial flow past a cylinder with a free-spinning base. A subsonic wind tunnel with a forward-sting mounted spinning cylinder is used for experiments. In addition, a free-jet facility is used for benchmarking the experimental set up. Experiments are performed for a range of spin rates and free stream flow conditions. An anisotropic two-equation Reynolds-stress model that incorporates the effect of rotation-modified energy spectrum and swirl is used to perform computations for the flow past axially rotating cylinders. Both rigid cylinders as well as that of cylinders with free-spinning base are considered from a computational point of view. Applications involving the design of projectiles are discussed.

  1. Electron-electron interaction in projectile electron loss

    SciTech Connect

    Huelskoetter, H.; Meyerhof, W.E.; Dillard, E.A.; Guardala, N.; Spooner, D.W. ); Feinberg, B. ); Belkacem, A. Sciences Division, Building 71-259, Lawrence Berkeley Laboratory, One Cyclotron Road, Berkeley, CA ); Alonso, J.R.; Krebs, G.F.; McMahan, M.A.; Rude, B.S ); Blumenfeld, L.; Gould, H. ); Rhoades-Brown, M.E. ); Schweppe, J. (Chemical Sciences Division, Building 71-259, Lawrence Berkeley Laboratory, One Cyclotron Road, Berkeley, CA (

    1991-08-01

    In ion-atom collisions where the projectile is ionized, target electrons act not only coherently by screening the target nucleus but they may also act incoherently by directly ejecting a projectile electron. This electron-electron interaction should be relatively most important for targets that have a low nuclear charge, since the cross section for a neutral target is roughly proportional to {ital Z}{sub {ital t}}{sup 2}+{ital Z}{sub {ital t}}, where {ital Z}{sub {ital t}}{sup 2} is the contribution due to the target nucleus and {ital Z}{sub {ital t}} comes from the target electrons. In order to investigate the electron-electron interaction, we have measured and calculated cross sections for Li{sup 2+}, C{sup 5+}, and O{sup 7+} on H{sub 2} and He, Au{sup 52+} on H{sub 2}, He, C, and N{sub 2}, Au{sup 75+} on H{sub 2} and N{sub 2}, U{sup 86+} on H{sub 2} and He, and U{sup 90+} on H{sub 2}. The collision energies range from 0.75 to 405 MeV/nucleon. The calculations have been performed in the plane-wave Born approximation. We demonstrate that for energies where the target electrons have sufficient kinetic energy in the projectile frame to ionize the projectile, the electron-electron interaction can lead to a significant increase in the total electron-loss cross section.

  2. Measuring the Effects of Lift and Drag on Projectile Motion

    ERIC Educational Resources Information Center

    Cross, Rod

    2012-01-01

    The trajectory of a projectile through the air is affected both by gravity and by aerodynamic forces. The latter forces can conveniently be ignored in many situations, even when they are comparatively large. For example, if a 145-g, 74-mm diameter baseball is pitched at 40 ms[superscript -1] (89.5 mph), it experiences a drag force of about 1.5 N.…

  3. Learning Projectile Motion with the Computer Game ``Scorched 3D``

    NASA Astrophysics Data System (ADS)

    Jurcevic, John S.

    2008-01-01

    For most of our students, video games are a normal part of their lives. We should take advantage of this medium to teach physics in a manner that is engrossing for our students. In particular, modern video games incorporate accurate physics in their game engines, and they allow us to visualize the physics through flashy and captivating graphics. I recently used the game "Scorched 3D" to help my students understand projectile motion.

  4. Projectile and Lab Frame Differential Cross Sections for Electromagnetic Dissociation

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Adamczyk, Anne; Dick, Frank

    2008-01-01

    Differential cross sections for electromagnetic dissociation in nuclear collisions are calculated for the first time. In order to be useful for three - dimensional transport codes, these cross sections have been calculated in both the projectile and lab frames. The formulas for these cross sections are such that they can be immediately used in space radiation transport codes. Only a limited amount of data exists, but the comparison between theory and experiment is good.

  5. Post-mitigation impact risk assessment for NASA's DART kinetic impactor mission

    NASA Astrophysics Data System (ADS)

    Eggl, Siegfried; Hestroffer, Daniel; DART, AIM

    2016-10-01

    Field-testing kinetic impactors to deflect potentially hazardous asteroids (PHAs) is essential to better understand the challenges of future asteroid impact threat mitigation. The Asteroid Impact and Deflection Assessment mission (AIDA, Cheng et al. 2016), a collaborative effort between NASA and ESA, offers a timely opportunity to validate kinetic impact deflection strategies. Although the main goal of NASA's kinetic impactor (DART) is to change the circumprimary orbit of (65803) Didymos' moonlet, the imparted momentum will also slightly change the heliocentric orbit of the whole binary asteroid system. Given the high degree of non-linearity of the near-Earth dynamical environment, however, even a small change in initial conditions can affect long term predictions of the encounter distances between Didymos and the Earth. Belonging to the dynamical class of PHAs, (65803) Didymos has several encounters with the Earth over the upcoming decades, some of which are closer than 20 lunar distances. In order to confirm that no planetary safety issues arise as a consequence of DART, we conducted a post-mitigation impact risk assessment (PMIRA, Eggl et al. 2015) for the currently foreseen DART impact trajectories. In this contribution we present the latest PMIRA results and discuss the role of ESA's AIM spacecraft in reducing uncertainties arising in the deflection process.

  6. Comparison of experimental and numerical studies of the performance characteristics of a pumped counterflow virtual impactor

    SciTech Connect

    Kulkarni, Gourihar R.; Pekour, Mikhail S.; Afchine, Armin; Murphy, Daniel M.; Cziczo, Daniel J.

    2011-01-03

    Experiments and Computational Fluid Dynamic (CFD) simulations were performed to evaluate the performance characteristics of a Pumped Counterflow Virtual Impactor (PCVI). Tests were conducted for various flow configurations for which the diameter at which 50% of the particles were transmitted was determined. Experimentally determined 50% cutpoints varied from 2.2 to 4.8 micrometers and CFD predicted diameters agreed within ± 0.4 microns. Both experimental and CFD results showed similar transmission efficiency (TE) curves. CFD TE was always greater than experimental results, most likely due to impaction losses in fittings not included in the simulations. Ideal transmission, corresponding to 100% TE, was never realized in either case due to impaction losses and small scale flow features such as eddies. Areas where CFD simulations showed such flow recirculation zones were also found to be the locations where particulate residue was deposited during experiments. CFD parametric tests showed that PCVI performance can be affected by the nozzle geometry and misalignment between the nozzle and collector orifice. We conclude that CFD can be used with confidence for counterflow virtual impactor (CVI) design. Modifications to improve the performance characteristics of the PCVI are suggested.

  7. Fabrication and Characterization of Graded Impedance Gas Gun Impactors from Tape Cast Metal Powders

    SciTech Connect

    Martin, L P; Nguyen, J H

    2005-11-21

    Fabrication of compositionally graded structures for use as light-gas gun impactors has been demonstrated using a tape casting technique. Mixtures of metal powders in the Mg-Cu system were cast into a series of tapes with uniform compositions ranging from 100% Mg to 100% Cu. The individual compositions were fabricated into monolithic pellets for characterization by laminating multiple layers together, thermally removing the organics, and hot-pressing to near-full density. The pellets were characterized by optical and scanning electron microscopy, X-ray diffraction, and measurement of density and sound wave velocity. The density and acoustic impedance were observed to vary monotonically (and nearly linearly) with composition. Graded structures were fabricated by stacking layers of different compositions in a sequence calculated to yield a desired acoustic impedance profile. The measured physical properties of the graded structures compare favorably with those predicted from the monolithic-pellet characteristics. Fabrication of graded impactors by this technique is of significant interest for providing improved control of the pressure profile in gas gun experiments.

  8. GPU-enabled projectile guidance for impact area constraints

    NASA Astrophysics Data System (ADS)

    Rogers, Jonathan

    2013-05-01

    Guided projectile engagement scenarios often involve impact area constraints, in which it may be less desirable to incur miss distance on one side of a target or within a specified boundary near the target area. Current projectile guidance schemes such as impact point predictors cannot handle these constraints within the guidance loop, and may produce dispersion patterns that are insensitive to these constraints. In this paper, a new projectile guidance law is proposed that leverages real-time Monte Carlo impact point prediction to continually evaluate the probability of violating impact area constraints. The desired aim point is then adjusted accordingly. Real-time Monte Carlo simulation is enabled within the feedback loop through use of graphics processing units (GPU's), which provide parallel pipelines through which a dispersion pattern can routinely be predicted. The result is a guidance law that can achieve minimum miss distance while avoiding impact area constraints. The new guidance law is described and formulated as a nonlinear optimization problem which is solved in real-time through massively-parallel Monte Carlo simulation. An example simulation is shown in which impact area constraints are enforced and the methodology of stochastic guidance is demonstrated. Finally, Monte Carlo simulations are shown which demonstrate the ability of the stochastic guidance scheme to avoid an arbitrary set of impact area constraints, generating an impact probability density function that optimally trades miss distance within the restricted impact area. The proposed guidance scheme has applications beyond smart weapons to include missiles, UAV's, and other autonomous systems.

  9. Chunk projectile launch using the Sandia Hypervelocity Launcher Facility

    SciTech Connect

    Chhabildas, L.C.; Trucano, T.G.; Reinhart, W.D.; Hall, C.A.

    1994-07-01

    An experimental technique is described to launch an intact ``chunk,`` i.e. a 0.3 cm thick by 0.6 cm diameter cylindrical titanium alloy (Ti-6Al-4V) flyer, to 10.2 km/s. The ability to launch fragments having such an aspect ratio is important for hypervelocity impact phenomenology studies. The experimental techniques used to accomplish this launch were similar but not identical to techniques developed for the Sandia HyperVelocity Launcher (HVL). A confined barrel impact is crucial in preventing the two-dimensional effects from dominating the loading response of the projectile chunk. The length to diameter ratio of the metallic chunk that is launched to 10.2 km/s is 0.5 and is an order of magnitude larger than those accomplished using the conventional hypervelocity launcher. The multi-dimensional, finite-difference (finite-volume), hydrodynamic code CTH was used to evaluate and assess the acceleration characteristics i.e., the in-bore ballistics of the chunky projectile launch. A critical analysis of the CTH calculational results led to the final design and the experimental conditions that were used in this study. However, the predicted velocity of the projectile chunk based on CTH calculations was {approximately} 6% lower than the measured velocity of {approximately}10.2 km/S.

  10. Dark-ray and dark-floor craters on Ganymede, and the provenance of large impactors in the Jovian system

    SciTech Connect

    Schenk, P.M.; Mckinnon, W.B. Washington Univ., Saint Louis, MO )

    1991-02-01

    The dark-floor and dark-ray craters on the icy Jovian satellite, Ganymede, may derive their visual characteristics from impactor contamination. It is presently hypothesized that the rays darken as a result of the near-surface concentration of impactor material; this could occur, first, due to magnetic sputtering while the rays are bright, and subsequently, once a critical albedo is reached, due to thermal sublimation into discrete icy and nonicy patches. Voyager visible spectra of dark rays indicate that most large-ray systems are redder than grooved or cratered terrains, and are among the reddest units on Ganymede. More than half of the recent impactors on Ganymede may have been reddish D-type asteroids or comets, accounting for the albedos and colors of dark terrains on both Ganymede and Callisto. 108 refs.

  11. Laboratory investigations of marine impact events: Factors influencing crater formation and projectile survivability

    NASA Astrophysics Data System (ADS)

    Milner, D. J.; Baldwin, E. C.; Burchell, M. J.

    2008-12-01

    Given that the Earth’s surface is covered in around two-thirds water, the majority of impact events should have occurred in marine environments. However, with the presence of a water layer, crater formation may be prohibited. Indeed, formation is greatly controlled by the water depth to projectile diameter ratio, as discussed in this paper. Previous work has shown that the underlying target material also influences crater formation (e.g., Gault and Sonett 1982; Baldwin et al. 2007). In addition to the above parameters we also show the influence of impact angle, impact velocity and projectile density for a variety of water depths on crater formation and projectile survivability. The limiting ratio of water depth to projectile diameter on cratering represents the point at which the projectile is significantly slowed by transit through the water layer to reduce the impact energy to that which prohibits cratering. We therefore study the velocity decay produced by a water layer using laboratory, analytical and numerical modelling techniques, and determine the peak pressures endured by the projectile. For an impact into a water depth five times the projectile diameter, the velocity of the projectile is found to be reduced to 26-32% its original value. For deep water impacts we find that up to 60% of the original mass of the projectile survives in an oblique impact, where survivability is defined as the solid or melted mass fraction of the projectile that could be collected after impact.

  12. Molecular target and projectile angular scattering effects in stopping power and charge exchange at low-to-intermediate projectile energies

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Öhrn, Y.; Sabin, John R.; Deumens, E.

    2002-02-01

    We analyze the implications of the molecular structure of a target and the angular scattering effects on projectile-target collisions within the Electron-Nuclear Dynamics (END) approach. We show the suitability of the END method for the analysis of molecular scattering processes such as differential cross sections, charge exchange, and energy loss as required for the study of the stopping cross section. As a consequence of these effects, we show that the rovibronic energy loss becomes of greatest importance at low projectile energies. Furthermore, we find that the Bragg additivity rule and the linear-velocity dependence of the stopping cross section are not fulfilled at low projectile energies. Finally, we analyze the differences in the scattering processes for molecular and atomic targets, and show that in a transmission experiment with small exit window, the acceptance angle corresponds to different impact parameter selection for molecular targets than for atomic ones. Thus, the measured stopping cross section becomes a function of the acceptance angle of the experimental setup. We present results for hydrogen beams on H2 and N2 gas targets.

  13. Reevaluation of siderophile element abundances and ratios across the Cretaceous-Paleogene (K-Pg) boundary: Implications for the nature of the projectile

    NASA Astrophysics Data System (ADS)

    Goderis, S.; Tagle, R.; Belza, J.; Smit, J.; Montanari, A.; Vanhaecke, F.; Erzinger, J.; Claeys, Ph.

    2013-11-01

    projectile identification using (highly) siderophile elements. Only when considering improved databases of siderophile element concentrations in meteorites, in combination with linear regression analysis to calculate inter-element ratios from a large suite of ejecta deposit sites, the nature of the K-Pg projectile can be resolved. Application of this methodology to an extensive data set of continental and marine sites, very proximal to distal to the Chicxulub impact structure, supports a carbonaceous chondritic impactor (type CM or CO).

  14. Ancient impactor components preserved and reworked in martian regolith breccia Northwest Africa 7034

    NASA Astrophysics Data System (ADS)

    Goderis, Steven; Brandon, Alan D.; Mayer, Bernhard; Humayun, Munir

    2016-10-01

    Northwest Africa (NWA) 7034 and paired stones represent unique samples of martian polymict regolith breccia. Multiple breccia subsamples characterized in this work confirm highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, Pd) contents that are consistently elevated (e.g., Os ∼9.3-18.4 ppb) above indigenous martian igneous rocks (mostly <5 ppb Os), equivalent to ∼3 wt% of admixed CI-type carbonaceous chondritic material, and occur in broadly chondrite-relative proportions. However, a protracted history of impactor component (metal and sulfide) breakdown and redistribution of the associated HSE has masked the original nature of the admixed meteorite signatures. The present-day 187Os/188Os ratios of 0.119-0.136 record a wider variation than observed for all major chondrite types. Combined with the measured 187Re/188Os ratios of 0.154-0.994, the range in Os isotope ratios indicates redistribution of Re and Os from originally chondritic components early in the history of the regolith commencing at ∼4.4 Ga. Superimposed recent Re mobility reflects exposure and weathering at or near the martian and terrestrial surfaces. Elevated Os concentrations (38.0 and 92.6 ppb Os), superchondritic Os/HSE ratios, and 187Os/188Os of 0.1171 and 0.1197 measured for two subsamples of the breccia suggest the redistribution of impactor material at ∼1.5-1.9 Ga, possibly overlapping with a (partial) resetting event at ∼1.4 Ga recorded by U-Pb isotope systematics in the breccia. Martian alteration of the originally chondritic HSE host phases, to form Os-Ir-rich nuggets and Ni-rich pyrite, implies the influence of potentially impact-driven hydrothermal systems. Multiple generations of impactor component admixture, redistribution, and alteration mark the formation and evolution of the martian regolith clasts and matrix of NWA 7034 and paired meteorites, from the pre-Noachian until impact ejection to Earth.

  15. Orbital and physical characteristics of meter-scale impactors from airburst observations

    NASA Astrophysics Data System (ADS)

    Brown, P.; Wiegert, P.; Clark, D.; Tagliaferri, E.

    2016-03-01

    We have analyzed the orbits and ablation characteristics in the atmosphere of 59 Earth-impacting fireballs, produced by meteoroids 1 m in diameter or larger, described here as meter-scale. Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of meter-scale impactors at the Earth. We use fireballs producing recovered meteorites and well documented fireballs from ground-based camera networks to calibrate our ablation model interpretation of the observed peak height of luminosity as a function of speed. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. This is in contrast to earlier suggestions by Ceplecha (Ceplecha, Z. [1994]. Astron. Astrophys. 286, 967-970) that the majority of meter-tens of meter sized meteoroids are "… cometary bodies of the weakest known structure". We find a lower limit of ∼10-15% of our objects have a possible cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, also show evidence for weaker than average structure. Two events, Sumava and USG 20131121, have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though both were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several events in our population with the Taurid meteoroid complex; no other major meteoroid streams show probable linkages to the orbits of our meter-scale population. Our impactors cover almost four orders of magnitude in mass, but

  16. Targeting the (3.8-4.0 Ga) Impactors: Siderophile Element Signatures of Lunar Impact Melts

    NASA Astrophysics Data System (ADS)

    Bennett, V.; Norman, M.; Ryder, G.

    2001-12-01

    impactor type using individual samples can potentially give misleading results and consideration of impact-related fractionation using high precision data for suites of impact breccias is required. An additional sample (77035) has a distinctly different HSE pattern and is more consistent with an impactor of ordinary or EL-type chondrite composition. It likely represents a discrete impact event that was sampled at the Apollo 17 site. The clear recognition of specific and different types of meteoritic impactors indicates a diverse population of planetesimals bombarded the Moon, and that the lunar crust was not heavily contaminated with HSE prior to 3.8-4.0 Ga, a feature more consistent with a late cataclysm than a smoothly declining accretionary flux.

  17. Characteristics and measurement of supersonic projectile shock waves by a 32-microphone ring array

    NASA Astrophysics Data System (ADS)

    Chang, Ho; Wu, Yan-Chyuan; Tsung, Tsing-Tshih

    2011-08-01

    This paper discusses about the characteristics of supersonic projectile shock wave in muzzle region during firing of high explosive anti-tank (HEAT) and high explosive (HE) projectiles. HEAT projectiles are fired horizontally at a muzzle velocity of Mach 3.5 from a medium caliber tank gun equipped with a newly designed multi-perforated muzzle brake, whereas HE projectiles are fired at elevation angles at a muzzle velocity of Mach 2 from a large caliber howitzer equipped with a newly designed double-baffle muzzle brake. In the near field, pressure signatures of the N-wave generated from projectiles are measured by 32-microphone ring array wrapped by cotton sheath. Records measured by the microphone array are used to demonstrate several key characteristics of the shock wave of supersonic projectile. All measurements made in this study can be a significant reference for developing guns, tanks, or the chassis of fighting vehicles.

  18. Numerical study on the high-speed water-entry of hemispherical and ogival projectiles

    NASA Astrophysics Data System (ADS)

    Guo, Zitao; Zhang, Wei; Wei, Gang; Ren, Peng

    2012-03-01

    The water entry problem is considered as a classic problem which has a long research history; however, projectile water entry is still a difficult problem that has not been completely solved. In this paper, the effects of the projectile nose shape on laws of velocity attenuations for all projectiles were studied by a series of numerical simulations using the AUTODYN-2D. The result showed that the drag coefficient increases monotonically with the initial velocities for an identical projectile and decreases with the CRH values for projectiles at the same velocity. A simple and effective model was proposed to determine the relations between the drag coefficients, nose shape coefficient and initial velocities of projectiles.

  19. An asteroid breakup 160 Myr ago as the probable source of the K/T impactor.

    PubMed

    Bottke, William F; Vokrouhlický, David; Nesvorný, David

    2007-09-01

    The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past approximately 100 Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a approximately 170-km-diameter body (carbonaceous-chondrite-like) that broke up 160(-20)+30Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago.

  20. Global distribution of large lunar craters: implications for resurfacing and impactor populations.

    PubMed

    Head, James W; Fassett, Caleb I; Kadish, Seth J; Smith, David E; Zuber, Maria T; Neumann, Gregory A; Mazarico, Erwan

    2010-09-17

    By using high-resolution altimetric measurements of the Moon, we produced a catalog of all impact craters ≥20 kilometers in diameter on the lunar surface and analyzed their distribution and population characteristics. The most-densely cratered portion of the highlands reached a state of saturation equilibrium. Large impact events, such as Orientale Basin, locally modified the prebasin crater population to ~2 basin radii from the basin center. Basins such as Imbrium, Orientale, and Nectaris, which are important stratigraphic markers in lunar history, are temporally distinguishable on the basis of crater statistics. The characteristics of pre- and postmare crater populations support the hypothesis that there were two populations of impactors in early solar system history and that the transition occurred near the time of the Orientale Basin event.

  1. An asteroid breakup 160 Myr ago as the probable source of the K/T impactor.

    PubMed

    Bottke, William F; Vokrouhlický, David; Nesvorný, David

    2007-09-01

    The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past approximately 100 Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a approximately 170-km-diameter body (carbonaceous-chondrite-like) that broke up 160(-20)+30Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago. PMID:17805288

  2. The drag force on a subsonic projectile in a fluid complex plasma

    SciTech Connect

    Ivlev, A. V.; Zhukhovitskii, D. I.

    2012-09-15

    The incompressible Navier-Stokes equation is employed to describe a subsonic particle flow induced in complex plasmas by a moving projectile. Drag forces acting on the projectile in different flow regimes are calculated. It is shown that, along with the regular neutral gas drag, there is an additional force exerted on the projectile due to dissipation in the surrounding particle fluid. This additional force provides significant contribution to the total drag.

  3. Geochemical arguments for an Earth-like Moon-forming impactor.

    PubMed

    Dauphas, Nicolas; Burkhardt, Christoph; Warren, Paul H; Fang-Zhen, Teng

    2014-09-13

    Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ(17)O, ε(50)Ti and ε(54)Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ(30)Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε(182)W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10-20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30-40 Myr).

  4. Geochemical arguments for an Earth-like Moon-forming impactor.

    PubMed

    Dauphas, Nicolas; Burkhardt, Christoph; Warren, Paul H; Fang-Zhen, Teng

    2014-09-13

    Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ(17)O, ε(50)Ti and ε(54)Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ(30)Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε(182)W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10-20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30-40 Myr). PMID:25114316

  5. Direct-trauma model of posttraumatic syringomyelia with a computer-controlled motorized spinal cord impactor.

    PubMed

    Wong, Johnny H Y; Song, Xin; Hemley, Sarah J; Bilston, Lynne E; Cheng, Shaokoon; Stoodley, Marcus A

    2016-05-01

    OBJECTIVE The pathogenesis of posttraumatic syringomyelia remains enigmatic and is not adequately explained by current theories. Experimental investigations require a reproducible animal model that replicates the human condition. Current animal models are imperfect because of their low reliability, severe neurological deficits, or dissimilar mechanism of injury. The objective of this study was to develop a reproducible rodent model of posttraumatic syringomyelia using a spinal cord impactor that produces an injury that more closely mimics the human condition and does not produce severe neurological deficits. METHODS The study consisted of 2 parts. Seventy animals were studied overall: 20 in Experiment 1 and 48 in Experiment 2 after two rats with severe deficits were killed early. Experiment 1 aimed to determine the optimal force setting for inducing a cystic cavity without neurological deficits using a computer-controlled motorized spinal cord impactor. Twenty animals received an impact that ranged from 50 to 150 kDyn. Using the optimal force for producing an initial cyst determined from Experiment 1, Experiment 2 aimed to compare the progression of cavities in animals with and those without arachnoiditis induced by kaolin. Forty-eight animals were killed at 1, 3, 6, or 12 weeks after syrinx induction. Measurements of cavity size and maximum anteroposterior and lateral diameters were evaluated using light microscopy. RESULTS In Experiment 1, cavities were present in 95% of the animals. The duration of limb weakness and spinal cord cavity size correlated with the delivered force. The optimal force chosen for Experiment 2 was 75 kDyn. In Experiment 2, cavities occurred in 92% of the animals. Animals in the kaolin groups developed larger cavities and more vacuolations and enlarged perivascular spaces than those in the nonkaolin groups. CONCLUSIONS This impact model reliably produces cavities that resemble human posttraumatic syringomyelia and is suitable for further

  6. Good Cascade Impactor Practice (GCIP) and considerations for "in-use" specifications.

    PubMed

    Nichols, S C; Mitchell, J P; Shelton, C M; Roberts, D L

    2013-03-01

    The multi-stage cascade impactor (CI) is widely used to determine aerodynamic particle size distributions (APSDs) of orally inhaled products. Its size-fractionating capability depends primarily on the size of nozzles of each stage. Good Cascade Impactor Practice (GCIP) requires that these critical dimensions are linked to the accuracy of the APSD measurement based on the aerodynamic diameter size scale. Effective diameter (Deff) is the critical dimension describing any nozzle array, as it is directly related to stage cut-point size (d50). d50 can in turn be determined by calibration using particles of known aerodynamic diameter, providing traceability to the international length standard. Movements in Deff within manufacturer tolerances for compendial CIs result in the worst case in shifts in d50 of <±10%. Stage mensuration therefore provides satisfactory control of measurement accuracy. The accurate relationship of Deff to d50 requires the CI system to be leak-free, which can be checked by sealing the apparatus at the entry to the induction port and isolating it from the vacuum source and measuring the rate of pressure rise before each use. Mensuration takes place on an infrequent basis compared with the typical interval between individual APSD determinations. Measurement of stage flow resistance (pressure drop; ΔPstage) could enable the user to know that the CI stages are fit for use before every APSD measurement, by yielding an accurate measure of Deff. However, more data are needed to assess the effects of wear and blockage before this approach can be advocated as part of GCIP.

  7. Geochemical arguments for an Earth-like Moon-forming impactor

    PubMed Central

    Dauphas, Nicolas; Burkhardt, Christoph; Warren, Paul H.; Fang-Zhen, Teng

    2014-01-01

    Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ17O, ε50Ti and ε54Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ30Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε182W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10–20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30–40 Myr). PMID:25114316

  8. Dynamical Sequestration of the Moon-Forming Impactor in Co-Orbital Resonance with Earth

    NASA Astrophysics Data System (ADS)

    Kortenkamp, Stephen J.; Hartmann, William J.

    2015-11-01

    Recent concerns about the giant impact hypothesis for the origin of the moon, and an associated “isotope crisis” are assuaged if the impactor was a local object that formed near Earth and the impact occurred relatively late. We investigated a scenario that may meet these criteria, with the moon-forming impactor originating in 1:1 co-orbital resonance with Earth. Using N-body numerical simulations we explored the dynamical consequences of placing Mars-mass companions in various co-orbital configurations with a proto-Earth having 90% of its current mass. We modeled configurations that include the four terrestrial planets as well as configurations that also include the four giant planets. In both the 4- and 8-planet models we found that a single additional Mars-mass companion typically remains a stable co-orbital of Earth for the entire 250 million year (Myr) duration of our simulations (33 of 34 simulations). In an effort to destabilize such a system we carried out an additional 45 simulations that included a second Mars-mass co-orbital companion. Even with two Mars-mass companions sharing Earth’s orbit most of these models (28) also remained stable for the entire 250 Myr duration of the simulations. Of the 17 two-companion models that eventually became unstable 12 impacts were observed between Earth and an escaping co-orbital companion. The average delay we observed for an impact of a Mars-mass companion with Earth was 101 Myr, and the longest delay was 221 Myr. Several of the stable simulations involved unusual 3-planet co-orbital configurations that could exhibit interesting observational signatures in plantetary transit surveys.

  9. Correlation effects due to an axial propagation of projectiles in a dusty plasma

    SciTech Connect

    Ali, S.; Nasim, M.H.; Murtaza, G.

    2005-03-01

    Generalized expressions for the Debye potential and the wake field potential are derived due to an axial propagation of dust grain projectiles. The dust grain projectiles are assumed to lie on sets of concentric circles propagating through the dusty plasma with a constant velocity along the z axis. Each circle carries N number of dust grain projectiles having radius r{sub l} and angular position (2{pi}m)/N. A couple of specific cases of electrostatic potential due to four and eight projectiles are studied in some detail both analytically and numerically.

  10. Numerical Study on the High-Speed Water-Entry of Hemispherical and Ogival Projectiles

    NASA Astrophysics Data System (ADS)

    Guo, Zitao; Zhang, Wei; Wei, Gang; Xiao, Xinke

    2011-06-01

    The water entry problem is considered as a classic problem which has a long research history, however, projectile water entry is still a difficult problem that has not been completely solved. In this paper, the effects of the projectile nose shape on laws of velocity attenuations for all projectiles were studied by a series of numerical simulations using the AUTODYN-2D. The projectiles including the hemispherical and ogival projectiles with three CRH (caliber-radius-head) have been set to a constant mass and their water-entry velocities were in the range of 300m/s ~ 1500m/s. The result showed that the drag coefficient increases monotonically with increasing initial velocities for an identical projectile but decrease with the increase of the CRH for ogival projectiles at the same velocity. It was found that the relation between the drag coefficient and the initial velocities for all projectiles can be expressed as a general equation. Correspondingly, the relation between the drag coefficient and the CRH value of ogival projectiles was also presented in this paper.

  11. Influence of Nutation of the Projectile on Fracture of the Anisotropic Target

    NASA Astrophysics Data System (ADS)

    Radchenko, Andrey; Radchenko, Pavel

    2012-02-01

    In actual practice the direction of the vector of velocity, as a rule, doesn't coincide with the direction of a longitudinal axis of a moving body, and makes with it some angle named the angle of nutation. The nutation influence on process of interaction of the projectile and a target is defined not only by its size, but also geometrical and kinematic parameters of the process. It is obvious that for a case of the prolonged projectile the angle of nutation influence is more considerable, than for the compact projectile because in this case the nutation angle presence changes not only a picture of strain-stress state of interaction bodies, but also leads to loss of stability in the projectile. The three-dimensional problem of oblique high-velocity interaction of the prolonged cylindrical projectile from steel with an anisotropic target from organoplastic is considered. Lengthening of the projectile makes from 15 to 30 calibers, the range of initial velocities of the projectile from 700 to 3000 m/sec is researched. Modeling is carried out numerically by a method of finite elements. Influence of nutation angle and rotation of the projectile on fracture of target and stability of the projectile is analyzed.

  12. Analysis of electrostatic charge on small-arms projectiles

    NASA Astrophysics Data System (ADS)

    Vinci, Stephen; Zhu, Jack; Hull, David

    2012-06-01

    Triboelectric (frictional) and combustion processes impart electrostatic charge on projectiles as they are fired. Additional charging and discharging processes alter the magnitude of charge in-flight and are complex functions of a plethora of environmental conditions. There is an interest in using electric-field sensors to help detect and track projectiles in counter-sniper and projectile ranging systems. These applications require knowledge of the quantity of charge, as well as the sensitivity of electric-field sensors. The U.S. Army Research Laboratory (ARL) took part in multiple experiments at Aberdeen Proving Grounds (APG) to simulate a battlefield-like environment. Sensors were placed in strategic locations along the bullets' paths and recorded the electric-field signatures of charged small-arms bullets. The focus of this effort was to analyze the electric-field signatures collected during the APG experiment in order to estimate electrostatic charge on the bullets. Algorithms were written to extract electric-field bullet signatures from raw data; these signatures were further processed to estimate the miss distance, velocity and charge. The estimates of range and velocity were compared to similar estimates from acoustic signatures for verification. Ground-truth Global Positioning System (GPS) data were used to independently calculate ranges, azimuths, and miss distances. Signatures were filtered to remove clutter signals from power lines and other unwanted field sources. Closed-form equations were then fitted to the collected signatures to retrieve estimates for the magnitude of charge on the bullets. Test data, collected with sensors placed on a wall, showed enhanced E-field intensity. A Method of Moments (MoM) model of the wall was created to improve signature simulation. Detectable charges on bullets were found to exist in the 1 pC to 1 nC (10-12 - 10-9 C) range. Relationships between estimated charge, gun type, bullet caliber, noise thresholds and number

  13. Mass spectrometric analysis with cluster projectiles and coincidence counting

    SciTech Connect

    Cox, B.D.

    1992-01-01

    Methods for maximizing the amount of secondary ion information, per primary projectile, are described. The method is based on time-of-flight mass spectrometry and event-by-event coincidence counting. The information obtained from coincidence counting time-of-flight mass spectrometry includes: (a) surface composition, (b) relative concentrations, and (c) degree of intermolecular mixing. The technique was applied to the study of an important new class of polymers: polymer blends. Secondary ion mass spectrometry, when applied to the analysis of synthetic polymers, induces backbone fragmentation which is characteristic of the homopolymer. The characteristic fingerprint peaks from polystyrene and poly(vinyl methyl ether) were used to identify the presence of these two polymers in a polymer blend. The percent coincidence between the characteristic secondary ions from each component of the blend were used to determine both the relative concentration and the degree of molecular mixing. Results indicate molecular segregation of the two polymers on the film surface. The largest degree of segregation was determined for the phase separated blends. The performance of this technique depends on the desorption efficiency of the primary projectiles. In practice one seeks primary ions which are surface sensitive, have controllable parameters such as size, velocity, and charge state, and generate high secondary ion yields. Focus was placed on the use of keV organic cluster projectiles to meet these criteria. Of interest to this study were C[sub 18] (chrysene), C[sub 24] (coronene), and C[sub 60] (buckminster-fulleren). Results indicate enhanced secondary ion yields for C[sub 60]. For example, when CsI is bombarded with 30 keV C[sub 60], the yields for I[sup [minus

  14. Increasing Student Engagement and Enthusiasm: A Projectile Motion Crime Scene

    NASA Astrophysics Data System (ADS)

    Bonner, David

    2010-05-01

    Connecting physics concepts with real-world events allows students to establish a strong conceptual foundation. When such events are particularly interesting to students, it can greatly impact their engagement and enthusiasm in an activity. Activities that involve studying real-world events of high interest can provide students a long-lasting understanding and positive memorable experiences, both of which heighten the learning experiences of those students. One such activity, described in depth in this paper, utilizes a murder mystery and crime scene investigation as an application of basic projectile motion.

  15. Ballistic Impact of Braided Composites With a Soft Projectile

    NASA Technical Reports Server (NTRS)

    Roberts, Gary D.; Pereira, J. Michael; Revilock, Duane M., Jr.; Binienda, Wieslaw; Xie, Ming; Braley, Mike

    2004-01-01

    Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Use of a soft projectile allows a large amount of kinetic energy to be transferred into strain energy in the target before penetration occurs. Failure modes were identified for flat aluminum plates and for flat composite plates made from a triaxial braid having a quasi-isotropic fiber architecture with fibers in the 0 and +/- 60 deg. directions. For the aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate to the fixed boundaries. For the composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the +/- 60 deg. fiber directions until triangular flaps opened to allow the projectile to pass through the plate. The damage size was only slightly larger than the initial impact area. It was difficult to avoid slipping of the fixed edges of the plates during impact, and slipping was shown to have a large effect on the penetration threshold. Failure modes were also identified for composite half-rings fabricated with the 0 deg. fibers aligned circumferentially. Slipping of the edges was not a problem in the half-ring tests. For the composite half-rings, fiber tensile failure also occurred in the back ply. However, cracks initially propagated from this site in a direction transverse to the 0 deg. fibers. The cracks then turned to follow the +/- 60 deg. fibers for a short distance before turning again to follow 0 deg. fibers until two approximately rectangular flaps opened to allow the projectile to pass through the plate. The damage size in the composite half-rings was also only slightly larger than the initial impact area. Cracks did not propagate to the boundaries, and no delamination was observed. The damage tolerance demonstrated by the quasi-isotropic triaxial braid composites

  16. Ionization of water molecules by fast charged projectiles

    SciTech Connect

    Dubois, A.; Carniato, S.; Fainstein, P. D.; Hansen, J. P.

    2011-07-15

    Single-ionization cross sections of water molecules colliding with fast protons are calculated from lowest-order perturbation theory by taking all electrons and molecular orientations consistently into account. Explicit analytical formulas based on the peaking approximation are obtained for differential ionization cross sections with the partial contribution from the various electron orbitals accounted for. The results, which are in very good agreement with total and partial cross sections at high electron and projectile energies, display a strong variation on molecular orientation and molecular orbitals.

  17. Comment on ‘Wind-influenced projectile motion’

    NASA Astrophysics Data System (ADS)

    Winther Andersen, Poul

    2015-11-01

    We comment on the article ‘Wind-influenced projectile motion’ by Bernardo et al (2015 Eur. J. Phys. 36 025016) where they examine the trajectory of a particle that is subjected to gravity and a linear air resistance plus the influence from the wind. They find by using the Lambert W function that the particle's trajectory for a special angle, the critical angle {θ }{{C}}, between the initial velocity and the horizontal is part of a straight line. In this comment we will show that this result can be proved without using the Lambert W function which is not that well known to beginning students of physics.

  18. Advances in digital memory telemeters for artillery projectiles

    NASA Astrophysics Data System (ADS)

    Szabo, L. R.; Osborne, W. I.

    The purpose of this paper is to review the progress currently being made in the semiconductor field and how these recent advances can be utilized in digital memory telemeters for gathering data from various artillery projectiles. Topics to be presented include: basic design considerations, high-g packaging techniques, and the high-g hardening of critical electronic components. In addition, a prototype memory telemeter, which is under development for ARDC's 155mm Ballistic Simulator, and the firing data it has recorded to date are discussed. Finally, a look at future advances in IC technology and its impact on digital memory telemeters is presented.

  19. Stagnation pressure activated fuel release mechanism for hypersonic projectiles

    DOEpatents

    Cartland, Harry E.; Hunter, John W.

    2003-01-01

    A propulsion-assisted projectile has a body, a cowl forming a combustion section and a nozzle section. The body has a fuel reservoir within a central portion of the body, and a fuel activation system located along the central axis of the body and having a portion of the fuel activation system within the fuel reservoir. The fuel activation system has a fuel release piston with a forward sealing member where the fuel release piston is adapted to be moved when the forward sealing member is impacted with an air flow, and an air-flow channel adapted to conduct ambient air during flight to the fuel release piston.

  20. Multiple ionization of neon induced by Li3+ and C3+ projectiles: influence of projectile screening in the ionization and electron capture channels

    NASA Astrophysics Data System (ADS)

    Ihani, J. S.; Luna, H.; Wolff, W.; Montenegro, E. C.

    2013-06-01

    Neq + (q = 1,2,3,4) ionization and charge exchange cross sections (total electron capture, single electron capture and transfer ionization) in the collisions with Li3+, with energies between 100 and 900 keV amu-1, and C3+, with energies between 250 and 500 keV amu-1 are reported. Bare Li3+ projectiles give a key benchmark to study the role of projectile screening in collisions involving dressed projectile ions, and the measurements have shown a strong screening effect for all n-fold recoil ion charge states in the ionization channel which, unexpectedly, does not appear for transfer ionization.

  1. Changes to the LANL gas driven two stage gun : projectile velocity measurement and etc.

    SciTech Connect

    Gustavsen, R. L.; Sheffield, S. A.; Alcon, R. R.; Medina, R. S.

    2001-01-01

    stage gun. It was necessary to use optical methods because electrical shorting pins damaged the projectile:, turned .the projectile causing tilted impacts, and sprayed the target with bits of broken pin. The first optical method involved cutting shrzllow grooves in the sides of the projectile at precisely measured intervals. Thc projectile pilssed through a single light beam focused in such a way that the grooves would alternately block and transmit light to a sensing system. This system didn't work because the groovas filled with smoke, blocking the light at all times after the projectile first broke the hearn. The second method used light rcflectetl off the projectile at four different positions. Light from a 400 mW laser was split into four oplical fibers. Half of the light reflected from the end of each B9er 'was retutncd to it phototnulitiplier. When the projectile passed in front of a fiber the amount of returned light increased. This system had a very poor signal to noise ratio: the amount of light returned when the projectile passed in front ofthe fiber was scarcely larger than the noise on the signals. 'I'hc third system used four stations at which laser light was transmitted from one optical fiber to another. 'The projectile passed close by tlhe sending or receiving fiber, rapidly cutting off the transmitted light. This method suffered from a lasix speckle pattern which changed with time thereby giving a constiintly changing inlerisiily. The fiber optic beam splitter used to split the laser light in methods two and three was also very nnstable: the amount of light split into any particular fiber varied with teinperature, vibration, and any movement of fibers. The method which was ultimately successful used it SmW, 670 nni laser diode at each of' four positions. A small lens focused this light to a point through which Ilie projectile passed. Transmitted light was imaged into 700 micron plastic fibers which relayed thhe light to a bank of photomultipliers

  2. Fiber-interferometric detection of gun-launched projectiles

    NASA Astrophysics Data System (ADS)

    Goodwin, Peter; Marshall, Bruce; Gustavsen, Richard; Lang, John; Pacheco, Adam; Loomis, Eric; Dattelbaum, Dana

    2015-06-01

    We are developing a new diagnostic useful for the non-invasive detection of projectile passage in the launch tube of a gas gun. The sensing element consists of a fiber-loop that is epoxy-bonded around the external circumference of launch tube. The hoop strain induced in the launch tube by the passage of the projectile causes a momentary expansion of the fiber loop. This transient change in path length is detected with high sensitivity using a fiber-optic based interferometer developed by the NSTec Special Technologies Laboratory. We have fielded this new diagnostic, along with fiber-Bragg grating (FBG) strain gauges we previously used for this purpose, on a variety of light gas guns used for shock compression studies at Los Alamos. Our preliminary results show that the fiber interferometer has improved sensitivity and dynamic range compared that of the FBG strain gauge approach. Moreover, the interferometric approach requires no hands-on alignment immediately prior to the experiment and is therefore easier to implement. Both approaches provide early, pre-event signals useful for triggering high-latency diagnostics.

  3. Evidence for a large radius of the 11Be projectile

    NASA Astrophysics Data System (ADS)

    So, W. Y.; Choi, K. S.; Cheoun, Myung-Ki; Kim, K. S.

    2016-05-01

    We investigate ratios of the elastic scattering cross section to Rutherford cross section, PE, and angular distributions of breakup cross section by using an optical model which exploits various long-range dynamic polarization potentials as well as short-range nuclear bare potentials for the 11Be projectile. From these simultaneous analyses, we extract a large radius of a halo projectile from the experimental data for PE and the angular distribution of the breakup cross section of the 11Be + 64Zn and 11 + 120Sn systems. It results from the fact that a large radius for the long-range nuclear potential is more reasonable for properly explaining these data simultaneously. The extracted reduced interaction radius turns out to be r0=3.18 ˜3.61 fm for 11Be nucleus, which is larger than the conventional value of r0=1.1 ˜1.5 fm used in the standard radius form R =r0A1 /3 . Furthermore, the larger radius as well as the normalization constant N is shown to be important for understanding Coulomb dipole strength distribution.

  4. Scale effect of spherical projectiles for stabilization of oblique detonation waves

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Sumiya, S.; Kasahara, J.; Matsuo, A.

    2015-03-01

    Oblique detonation waves (ODWs) were stabilized by launching a spherical projectile with 1.2-1.4 times the Chapman-Jouguet (C-J) velocity into detonable mixtures at rest. We used smaller projectiles (3.18 mm diameter) than those (4.76 mm diameter) in our previous studies and investigated the effect of the projectile scale on the stabilization of ODWs. We carried out high time resolution schlieren visualization using a high-speed camera. The detonable mixtures used were stoichiometric oxygen mixtures with acetylene, ethylene or hydrogen. They were diluted with argon with a 50 % volumetric fraction, and a dilute mixture containing 75 % argon was also tested for the acetylene/oxygen mixture. Here, we discuss the detonation stability in terms of the curvature effect arising from the three-dimensional nature of a stabilized ODW around a projectile. The curvature effect attenuated the detonation wave to below its C-J velocity in the vicinity of the projectile before the wave velocity asymptotically reached the C-J velocity in the far field. Our previous study showed that the propagation limit of the curvature effect is responsible for the stabilizing criticality of detonation waves. By obtaining detailed distributions of the wave propagation velocity and radius of curvature at the stabilizing criticality, we showed that the radius of curvature at the local minimum point of the wave propagation velocity represents the critical radius of curvature required for curved self-sustained detonation. In this study, we focused on this critical mode of the stabilized ODW for a small projectile (3.18 mm diameter). Distributions of the wave velocity and radius of curvature were obtained in the critical mode of the stabilized ODW. We compare these distributions with those for a larger projectile (4.76 mm diameter) and discuss the stabilizing criticality. For the small projectile, the observed combustion regimes had qualitatively the same trend for the initial pressure of the mixture

  5. Influence of rheology and giant impactors on the terrestrial core formation

    NASA Astrophysics Data System (ADS)

    Golabek, G. J.; Gerya, T.; Kaus, B. J.; Ziethe, R.; Moll, G.; Tackley, P. J.

    2009-12-01

    Knowledge about the terrestrial core formation mechanism is still very limited. Several core formation modes have been proposed: The fracturing mode suggests that a central unmelted region is displaced by a degree one mode from the center of the accreting body and is fragmented due to the large stresses created by an overlying asymmetric iron layer (Stevenson, 1981). In contrast, core formation via iron diapirs (e.g. Ziethe and Spohn, 2007), which can be formed by giant impacts (e.g. Ricard et al, 2009), has been proposed. We investigate which core formation mode is active under certain conditions. Therefore we perform 2D simulations using the code I2ELVIS applying the newly developed “spherical-Cartesian” methodology (Gerya and Yuen, 2007). It combines finite differences on a fully staggered rectangular Eulerian grid and Lagrangian marker-in-cell technique for solving momentum, continuity and temperature equations as well as the Poisson equation for gravity potential in a self-gravitating planetary body. In the model, the planetary body is surrounded by a low viscosity massless fluid (“sticky air”) to simulate a free surface. We apply a temperature- and stress-dependent viscoplastic rheology inside Mars- to Earth-sized bodies and include heat release due to radioactive decay, shear and adiabatic heating. As initial condition we use stochastically distributed iron diapirs with random sizes in the range of 50 to 100 km radius inside the accreting planet, representing the iron delivered by pre-differentiated impactors. Additionally, we add a giant impactor core into several models. For simplicity, we neglect the heating of the planetary body by the impact itself. We assume the impactor core to be at rest at the beginning of the simulation. A systematic investigation of the influence of silicate rheology, temperature and diapir radii on different-sized protoplanets is being performed. We show that depending on the silicate rheology, which is strongly dependent

  6. Spreadsheet Application Showing the Proper Elevation Angle, Points of Shot and Impact of a Projectile

    ERIC Educational Resources Information Center

    Benacka, Jan

    2015-01-01

    This paper provides the formula for the elevation angle at which a projectile has to be fired in a vacuum from a general position to hit a target at a given distance. A spreadsheet application that models the trajectory is presented, and the problem of finding the points of shot and impact of a projectile moving in a vacuum if three points of the…

  7. Treatment of Ion-Atom Collisions Using a Partial-Wave Expansion of the Projectile Wavefunction

    ERIC Educational Resources Information Center

    Wong, T. G.; Foster, M.; Colgan, J.; Madison, D. H.

    2009-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge…

  8. Reaction dynamics of {sup 34-38}Mg projectile with carbon target using Glauber model

    SciTech Connect

    Shama, Mahesh K.; Panda, R. N.; Sharma, Manoj K.; Patra, S. K.

    2015-08-28

    We have studied nuclear reaction cross-sections for {sup 34-38}Mg isotopes as projectile with {sup 12}C target at projectile energy 240AMeV using Glauber model with the conjunction of densities from relativistic mean filed formalism. We found good agreement with the available experimental data. The halo status of {sup 37}Mg is also investigated.

  9. An Analytic Approach to Projectile Motion in a Linear Resisting Medium

    ERIC Educational Resources Information Center

    Stewart, Sean M.

    2006-01-01

    The time of flight, range and the angle which maximizes the range of a projectile in a linear resisting medium are expressed in analytic form in terms of the recently defined Lambert W function. From the closed-form solutions a number of results characteristic to the motion of the projectile in a linear resisting medium are analytically confirmed,…

  10. Solution to Projectile Motion with Quadratic Drag and Graphing the Trajectory in Spreadsheets

    ERIC Educational Resources Information Center

    Benacka, Jan

    2010-01-01

    This note gives the analytical solution to projectile motion with quadratic drag by decomposing the velocity vector to "x," "y" coordinate directions. The solution is given by definite integrals. First, the impact angle is estimated from above, then the projectile coordinates are computed, and the trajectory is graphed at various launch angles and…

  11. Magnetic induction system for two-stage gun projectile velocity measurements

    SciTech Connect

    Moody, R L; Konrad, C H

    1984-05-01

    A magnetic induction technique for measuring projectile velocities has been implemented on Sandia's two-stage light gas gun. The system has been designed to allow for projectile velocity measurements to an accuracy of approx. 0.2 percent. The velocity system has been successfully tested in a velocity range of 3.5 km/s to 6.5 km/s.

  12. Projectile Motion on an Inclined Misty Surface: I. Capturing and Analysing the Trajectory

    ERIC Educational Resources Information Center

    Ho, S. Y.; Foong, S. K.; Lim, C. H.; Lim, C. C.; Lin, K.; Kuppan, L.

    2009-01-01

    Projectile motion is usually the first non-uniform two-dimensional motion that students will encounter in a pre-university physics course. In this article, we introduce a novel technique for capturing the trajectory of projectile motion on an inclined Perspex plane. This is achieved by coating the Perspex with a thin layer of fine water droplets…

  13. Real-time estimation of projectile roll angle using magnetometers: in-lab experimental validation

    NASA Astrophysics Data System (ADS)

    Changey, S.; Pecheur, E.; Wey, P.; Sommer, E.

    2013-12-01

    The knowledge of the roll angle of a projectile is decisive to apply guidance and control law. For example, the goal of ISL's project GSP (Guided Supersonic Projectile) is to change the flight path of an airdefence projectile in order to correct the aim error due to the target manoeuvres. The originality of the concept is based on pyrotechnical actuators and onboard sensors which control the angular motion of the projectile. First of all, the control of the actuators requires the precise control of the roll angle of the projectile. To estimate the roll angle of the projectile, two magnetometers are embedded in the projectile to measure the projection of the Earth magnetic field along radial axes of the projectiles. Then, an extended Kalman filter (EKF) is used to compute the roll angle estimation. As the rolling frequency of the GSP is about 22 Hz, it was easy to test the navigation algorithm in laboratory. In a previous paper [1], the In-Lab demonstration of this concept showed that the roll angle estimation was possible with an accuracy of about 1◦ . In this paper, the demonstration is extended to high-speed roll rate, up to 1000 Hz. Thus, two magnetometers, a DSP (Digital Signal Processor) and a LED (Light Eminent Diode), are rotated using a pneumatic motor; the DSP runs an EKF and a guidance algorithm to compute the trigger times of the LED. By using a high-speed camera, the accuracy of the method can be observed and improved.

  14. Dynamical Behavior of Ejecta Produced by the Proposed ISIS Kinetic Impactor Demonstration

    NASA Astrophysics Data System (ADS)

    Fahnestock, Eugene G.; Chesley, Steven R.; Farnocchia, Davide

    2014-05-01

    Impactor for Surface and Interior Science (ISIS) is a proposed mission of opportunity that would demonstrate and test kinetic impact (KI) for orbit modification of a hypothetical NEO to reduce its Earth impact probability. Unlike Deep Impact, this test entails measuring ΔV imparted to a far smaller asteroidal target body (Bennu) using another spacecraft in rendezvous with that body both before and after the KI event (OSIRIX-REx). To quantify any hazard to OSIRIS-REx from collision with liberated ejecta, we perform detailed study of the ejecta's dynamical behavior. For KI event energy matching a 440 kg impactor at 13.43 km/s closing velocity, we model crater formation and ejecta generation consistent with the small net surface acceleration in the targeted equatorial region of the sunlit hemisphere at the February 2021 impact epoch, and reasonable material strength for such a low-density rubble-pile. A crater ≈25 m in diameter is excavated over several minutes, liberating several thousand metric tons of material, with maximum velocity ≈34 m/s. We propagate ejecta under all relevant dynamical effects, including shape-model-derived full body gravity, differential solar tide acceleration, and solar radiation pressure (SRP) accounting for realistic particle size-frequency distribution, optical properties, and shadowing. We present the proportion of particles reaching the dynamical fates of return impact or exit from the region of importance to OSIRIS-REx operations, vs. time. We show where the re-accreted ejecta deposits on the surface, and the size-frequency distribution of the population remaining at 1, 5, 10, etc. days post-impact. We find clearing times from the system are nonlinearly dependent on particle size as expected, especially for low-velocity ejecta which stream away anti-sunward under the action of SRP within a paraboloid zone. Higher-velocity ejecta persist for longer durations within a sunward extension of the original ejecta cone. We visualize

  15. The effect of giant impactors on the magnetic field energy of an early Martian dynamo.

    NASA Astrophysics Data System (ADS)

    Drummond, McGregor; Thieulot, Cedric; Monteux, Julien

    2016-04-01

    Through the cratering record embedded on its surface, Mars is one of the key planets required for investigating the formation and impact frequency in the early history of our Solar System. This record also holds clues to the events that may have caused the observed hemispheric dichotomy and cessation of the magnetic field that was present within the first 500 Myr of the planets' formation. We investigate the influence of giant impacts on the early Martian dynamo using the numerical dynamo modelling code PARODY-JA [1]. We hypothesize that the input heat from a giant impact will decrease the total heat flux at the CMB through mantle heating which leads to a decrease in the Rayleigh number of the core. As boundary conditions for the heat flux anomaly size, we use numerical results of a 750 km diameter impactor from the Monteux and Arkani-Hamed, 2014 [2] study which investigated impact heating and core merging of giant impacts in early Mars. We also determine the decrease in Rayleigh number from the change in total heat flux at the CMB using these results, where the decrease after impact is due to shock heating at the CMB. We calculate the time-averaged total magnetic field energy for an initial homogeneous heat flux model using a range of Rayleigh numbers (5 x 103 - 1 x 10^5). The Rayleigh number is then decreased for three new models - homogeneous, north pole impact and equatorial impact - and the time-averaged energy again determined. We find that the energy decreases more in our impact models, compared with the homogeneous, along with a variation in energy between the north pole and equatorial impact models. We conclude that giant impacts in Mars' early history would have decreased the total magnetic energy of the field and the decrease in energy is also dependent on the location of the impact. The magnetic field could have been disrupted beyond recovery from a planetesimal-sized collision; such as the suggested Borealis basin forming impact, or through the

  16. On the Resistance of the Air at High Speeds and on the Automatic Rotation of Projectiles

    NASA Technical Reports Server (NTRS)

    Riabouchinski, D

    1921-01-01

    Here, the laws governing the flow of a compressible fluid through an opening in a thin wall are applied to the resistance of the air at high speeds, especially as applied to the automatic rotation of projectiles. The instability which we observe in projectiles shot into the air without being given a moment of rotation about their axis of symmetry, or without stabilizing planes, is a phenomenon of automatic rotation. It is noted that we can prevent this phenomenon of automatic rotation by bringing the center of gravity sufficiently near one end, or by fitting the projectile with stabilizing planes or a tail. The automatic rotation of projectiles is due to the suction produced by the systematic formation of vortices behind the extremity of the projectile moving with the wind.

  17. Acceleration of mini-projectiles using a small-caliber electrothermal gun for fusion applications

    SciTech Connect

    Kincaid, R.W.; Bourham, M.A.; Gilligan, J.G.

    1995-12-31

    The small-caliber electrothermal plasma gun SIRENS has been used to accelerate mini-projectiles to demonstrate the feasibility of using such guns as a pellet injector for fueling of future fusion reactors. The gun has been modified to accommodate acceleration of plastic projectiles to simulate frozen hydrogenic pellets required to fuel fusion reactors. Barrel sections are equipped with diagnostics for velocity and position of the projectile. The length of the acceleration path could be varied between 15 and 45 cm. The pulse forming network (PFN) can provide up to 100 kJ discharge energy over 0.1 to 1.0 ms pulse duration. The projectile velocities have been measured via a set of break wires. The ODIN code has been modified to account for the projectile mass, acceleration and friction. Plasma parameters compared to code results are discussed in detail.

  18. A LGG Arrangement for Cut-Off of the Projectile Sabot

    NASA Astrophysics Data System (ADS)

    Ioilev, Andrey G.; Bebenin, Gennady V.; Kalmykov, Petr N.; Shlyapnikov, Georgy P.; Lapichev, Nikolay V.; Salnikov, Aleksander V.; Sokolov, Sergey S.; Motlokhov, Vladimir N.

    2009-03-01

    Usually, light gas guns (LGG) are used to accelerate projectiles for experimental study of spacecraft shielding performance under impact of space debris. A projectile is placed into polymeric non-split sabot to provide obturation of gas in the LGG barrel. After exit from the barrel, the sabot or its fragments that fly after the projectile, should be separated (cut-off) or deviated from the projectile flight-line. According to a novel approach, a special guard ring mounted at the barrel muzzle is used for fragmentation of a spherical projectile sabot at exit from the LGG barrel, and thin plastic bonded HE placed at the surface of a bush in the guard-plate is used to cut-off the sabot fragments. This approach was tried by numerical simulation and proved by experimental testing.

  19. Observation of mass and velocity of projectile fragments produced by hypervelocity impact with lightweight ceramic targets

    NASA Astrophysics Data System (ADS)

    Saito, Fumikazu; Kawai, Nobuaki; Tamura, Hideki

    2012-03-01

    In order to characterize the dynamic fracture of Al projectiles caused by impact with lightweight ceramic targets, we perform hypervelocity impact experiments of lightweight ceramic targets using spherical Al projectiles accelerated by a mini two-stage light-gas gun, and we propose a new method for estimating fragment mass by quantitative image analysis. As materials for the targets, 1-mm thick mullite, silicon nitride, and alumina ceramics are chosen. Aluminum-alloy projectiles 2.0 mm in diameter are impacted onto the targets under normal impact conditions. The dynamic fracture of the targets and projectiles is observed using flash x-ray radiography. In comparison with silicon nitride and alumina targets, a mullite target breaks a projectile into smaller fragments, and the splay angle of the debris generated from a mullite target is larger than that of the other targets. These results suggest that mullite ceramic would be a promising structural member for a debris shield.

  20. Impact response of graphite-epoxy flat laminates using projectiles that simulate aircraft engine encounters

    NASA Technical Reports Server (NTRS)

    Preston, J. L., Jr.; Cook, T. S.

    1975-01-01

    An investigation of the response of a graphite-epoxy material to foreign object impact was made by impacting spherical projectiles of gelatin, ice, and steel normally on flat panels. The observed damage was classified as transverse (stress wave delamination and cracking), penetrative, or structural (gross failure): the minimum, or threshold, velocity to cause each class of damage was established as a function of projectile characteristics. Steel projectiles had the lowest transverse damage threshold, followed by gelatin and ice. Making use of the threshold velocities and assuming that the normal component of velocity produces the damage in nonnormal impacts, a set of impact angles and velocities was established for each projectile material which would result in damage to composite fan blades. Analysis of the operating parameters of a typical turbine fan blade shows that small steel projectiles are most likely to cause delamination and penetration damage to unprotected graphite-epoxy composite fan blades.

  1. Earliest Stone-Tipped Projectiles from the Ethiopian Rift Date to >279,000 Years Ago

    PubMed Central

    Sahle, Yonatan; Hutchings, W. Karl; Braun, David R.; Sealy, Judith C.; Morgan, Leah E.; Negash, Agazi; Atnafu, Balemwal

    2013-01-01

    Projectile weapons (i.e. those delivered from a distance) enhanced prehistoric hunting efficiency by enabling higher impact delivery and hunting of a broader range of animals while reducing confrontations with dangerous prey species. Projectiles therefore provided a significant advantage over thrusting spears. Composite projectile technologies are considered indicative of complex behavior and pivotal to the successful spread of Homo sapiens. Direct evidence for such projectiles is thus far unknown from >80,000 years ago. Data from velocity-dependent microfracture features, diagnostic damage patterns, and artifact shape reported here indicate that pointed stone artifacts from Ethiopia were used as projectile weapons (in the form of hafted javelin tips) as early as >279,000 years ago. In combination with the existing archaeological, fossil and genetic evidence, these data isolate eastern Africa as a source of modern cultures and biology. PMID:24236011

  2. Satellite and correlative measurements of the stratospheric aerosol. III - Comparison of measurements by SAM II, SAGE, dustsondes, filters, impactors and lidar

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.; Mcmaster, L. R.; Swissler, T. J.; Rosen, J. M.; Hofmann, D. J.

    1984-01-01

    The SAM II and SAGE satellite sensors, dustsondes, impactors, a filter collector and an airborne lidar were used in a large satellite validation experiment on July 16-19, 1979, at Poker Flat, Alaska. Independent measurements of extinction profiles by SAM II and SAGE are noted to agree with each other and with those derived from the other instruments (within combined uncertainties). The wire impactor-derived results, while also consistent with the others, are coarse due to the relatively large uncertainties in impactor-derived mass, extinction, and number of particles/unit volume whose radius is greater than x microns.

  3. Measuring Sub-micron Size Fractionated Particulate Matter on Aluminum Impactor Disks

    SciTech Connect

    Buchholz, B A; Zermeno, P; Hwang, H; Young, T M

    2009-07-28

    Sub-micron sized airborne particulate matter is not collected well on regular quartz or glass fiber filter papers. We used a micro-orifice uniform deposit impactor (MOUDI) to size fractionate particulate matter (PM) into six size fractions and deposit it on specially designed high purity thin aluminum disks. The MOUDI separated PM into fractions 56-100 nm, 100-180 nm, 180-320 nm, 320-560 nm, 560-1000 nm, and 1000-1800 nm. Since MOUDI have low flow rates, it takes several days to collect sufficient carbon on 47 mm foil disks. The small carbon mass (20-200 microgram C) and large aluminum substrate ({approx}25 mg Al) presents several challenges to production of graphite targets for accelerator mass spectrometry (AMS) analysis. The Al foil consumes large amounts of oxygen as it is heated and tends to melt into quartz combustion tubes, causing gas leaks. We describe sample processing techniques to reliably produce graphitic targets for {sup 14}C-AMS analysis of PM deposited on Al impact foils.

  4. Constraining the Flux of Impactors Postdating Heavy Bombardment Using U-Pb Ages of Impact Glasses

    NASA Technical Reports Server (NTRS)

    Nemchin, A. A.; Norman, M. L.; Ziegler, R. A.; Grange, M. L.

    2013-01-01

    Spherules of glass varying in size from a few micrometres to a few millimetres are common in the lunar regolith. While some of these glass beads are products of pyroclastic fire fountains others originate as impact melt ejected from the target that breaks into small droplets and solidifies as spherical particles while raining back to the lunar surface. These glasses preserve information about the chemical composition of the target and often contain sufficient amount of radioactive nuclides such as 40K to enable Ar-40-Ar-39 dating of individual beads. Studies measuring the age of glass beads have been used in attempts to establish variations in the flux of impactors hitting the Moon, particularly during the period that postdates the formation of major impact basins [1,2]. These studies proposed a possibility of spike in the impact flux about 800 Ma [2] and over the last 400 Ma [1]. More recently U-Th-Pb isotopic systems have been also utilized to determine the age of impact glasses from the Apollo 17 regolith [3]. Our aim is to extend the application of the U-Pb system in impact glasses to spherules isolated from Apollo 14 soil 14163 in an attempt to further investigate the applicability of this isotopic system to the chronology of impact glass beads and gain additional information on the impact flux in the inner Solar system.

  5. Characterization and airborne deployment of a new counterflow virtual impactor inlet

    NASA Astrophysics Data System (ADS)

    Shingler, T.; Dey, S.; Sorooshian, A.; Brechtel, F. J.; Wang, Z.; Metcalf, A.; Coggon, M.; Mülmenstädt, J.; Russell, L. M.; Jonsson, H. H.; Seinfeld, J. H.

    2012-02-01

    A new counterflow virtual impactor (CVI) inlet is introduced with details of its design, laboratory characterization tests, and deployment on an aircraft during the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). The CVI inlet addresses three key issues in previous designs; in particular, the inlet operates with: (i) negligible organic contamination; (ii) a significant sample flow rate to downstream instruments (~15 l min-1) that reduces the need for dilution; and (iii) a high level of accessibility to the probe interior for cleaning. Wind tunnel experiments characterized the cut size of sampled droplets and the particle size-dependent transmission efficiency in various parts of the probe. For a range of counter-flow rates and air velocities, the measured cut size was between 8.7-13.1 μm. The percentage error between cut size measurements and predictions from aerodynamic drag theory are less than 13%. The CVI was deployed on the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter for thirty flights during E-PEACE to study aerosol-cloud-radiation interactions off the central coast of California between July and August 2011. Results are reported to assess the performance of the inlet including comparisons of particle number concentration downstream of the CVI and cloud drop number concentration measured by two independent aircraft probes. Measurements downstream the CVI are also examined from one representative case flight coordinated with shipboard-emitted smoke that was intercepted in cloud by the Twin Otter.

  6. Characterisation and airborne deployment of a new counterflow virtual impactor inlet

    NASA Astrophysics Data System (ADS)

    Shingler, T.; Dey, S.; Sorooshian, A.; Brechtel, F. J.; Wang, Z.; Metcalf, A.; Coggon, M.; Mülmenstädt, J.; Russell, L. M.; Jonsson, H. H.; Seinfeld, J. H.

    2012-06-01

    A new counterflow virtual impactor (CVI) inlet is introduced with details of its design, laboratory characterisation tests and deployment on an aircraft during the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). The CVI inlet addresses three key issues in previous designs; in particular, the inlet operates with: (i) negligible organic contamination; (ii) a significant sample flow rate to downstream instruments (∼15 l min-1) that reduces the need for dilution; and (iii) a high level of accessibility to the probe interior for cleaning. Wind tunnel experiments characterised the cut size of sampled droplets and the particle size-dependent transmission efficiency in various parts of the probe. For a range of counter-flow rates and air velocities, the measured cut size was between 8.7-13.1 μm. The mean percentage error between cut size measurements and predictions from aerodynamic drag theory is 1.7%. The CVI was deployed on the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter for thirty flights during E-PEACE to study aerosol-cloud-radiation interactions off the central coast of California in July and August 2011. Results are reported to assess the performance of the inlet including comparisons of particle number concentration downstream of the CVI and cloud drop number concentration measured by two independent aircraft probes. Measurements downstream of the CVI are also examined from one representative case flight coordinated with shipboard-emitted smoke that was intercepted in cloud by the Twin Otter.

  7. Environmental continuous air monitor inlet with combined preseparator and virtual impactor

    DOEpatents

    Rodgers, John C.

    2007-06-19

    An inlet for an environmental air monitor is described wherein a pre-separator interfaces with ambient environment air and removes debris and insects commonly associated with high wind outdoors and a deflector plate in communication with incoming air from the pre-separator stage, that directs the air radially and downward uniformly into a plurality of accelerator jets located in a manifold of a virtual impactor, the manifold being cylindrical and having a top, a base, and a wall, with the plurality of accelerator jets being located in the top of the manifold and receiving the directed air and accelerating directed air, thereby creating jets of air penetrating into the manifold, where a major flow is deflected to the walls of the manifold and extracted through ports in the walls. A plurality of receiver nozzles are located in the base of the manifold coaxial with the accelerator jets, and a plurality of matching flow restrictor elements are located in the plurality of receiver nozzles for balancing and equalizing the total minor flow among all the plurality of receiver nozzles, through which a lower, fractional flow extracts large particle constituents of the air for collection on a sample filter after passing through the plurality of receiver nozzles and the plurality of matching flow restrictor elements.

  8. Peak acceleration during impact with helmet materials: effects of impactor mass and speed.

    PubMed

    Hutchinson, Timothy Paul

    2014-01-01

    The impact properties of six foam materials used for energy absorption as the liner of children's helmets, reported by Gimbel and Hoshizaki are considered further. In high-energy impacts, almost complete compression of the energy-absorbing material (bottoming out) may occur, and the severity of the impact increases greatly. Too soft a material means bottoming out occurs at low speeds, but if it is too stiff, the material itself is injurious. The fitting of equations to results in 'no bottoming out' and 'bottoming out' conditions may help assessment of what compromise is appropriate. The equations in this article correspond to peak acceleration being proportional to power functions of impactor speed and mass. 1. When there was no bottoming out, peak acceleration was found to be proportional to m (∧)(c-1).v (∧)(2c), with c being approximately 0.25. 2. For bottoming out, peak acceleration was found to be proportional to m (∧)(p).v (∧)(q), with p and q being approximately 2 and approximately 3. 3. The constants of proportionality were related to material density in a regular way.

  9. Counter sniper: a small projectile and gunfire localization system

    NASA Astrophysics Data System (ADS)

    Moore, Fritz; Leslie, Daniel H.; Hyman, Howard; Squire, Mark D.

    2001-02-01

    This paper describes a prototype sensor system for detection and 3D tracking of bullets and other small projectiles. The intended purpose of the system is to rapidly locate a sniper to a few meters accuracy at ranges to 1 km in three dimensions. The system detects and tracks a single bullet, and based on the measured 3D trajectory, backtracks to the sniper location. Details of the system are describe including optics, infrared camera, scanning system, laser ranging system, computer control and electronics, and data reduction algorithm. The system has been field tested against bullets, and has been shown to locate a sniper to a few meters accuracy at 500 meters range. Plans for improving tracking performance are also described.

  10. Lightweight Exoatmospheric Projectile (LEAP) test program. Supplemental environmental assessment

    NASA Astrophysics Data System (ADS)

    1992-06-01

    The proposed action is to modify previously planned Lightweight Exoatmospheric Projectile (LEAP) Test Program activities (LEAP EA, July 1991, Ref 32) at White Sands Missile Range (WSMR), New Mexico; Kwajalein Missile Range (KMR), U.S. Army Kwajalein Atoll (USAKA); and Wake Island. The proposed action includes modifications of flight trajectories for LEAP flights 3, 5, and 6. Two additional flights, LEAP-X and LEAP-7 have been added to the program. LEAP-X is a single rocket test flight from KMR and LEAP-7 is a two-rocket test flight from KMR and Wake Island. Component/assembly ground tests will take place at Orbital Sciences Corporation (OSC), Space Data Division (SDD), Chandler, Arizona; Phillips Laboratory, Edwards Air Force Base, California; Rocketdyne Division of Rockwell International; Boeing Aerospace and Electronics, Kent, Washington; Hughes Aircraft Corporation, Missile Systems Group, Canoga Park California; Aerojet, Sacramento, California; and Thiokol Corporation, Elkton, Maryland.

  11. Measuring the Effects of Lift and Drag on Projectile Motion

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2012-02-01

    The trajectory of a projectile through the air is affected both by gravity and by aerodynamic forces. The latter forces can conveniently be ignored in many situations, even when they are comparatively large. For example, if a 145-g, 74-mm diameter baseball is pitched at 40 ms-1 (89.5 mph), it experiences a drag force of about 1.5 N. The gravitational force on the ball 1.42 N. Nevertheless, the trajectory of a baseball pitched without spin is not strongly affected by the drag force. Because the ball is relatively heavy and the flight distance is relatively small (about 60 ft), the drag force reduces the ball speed by only about 10% by the time it reaches the batter. As a result, the time taken for the ball to reach the batter is only about 5% longer than in a vacuum, and the actual trajectory is also very similar.2

  12. OPTIMIZING TRANSPARENT ARMOR DESIGN SUBJECT TO PROJECTILE IMPACT CONDITIONS

    SciTech Connect

    Sun, Xin; Lai, Canhai; Gorsich, Tara; Templeton, Douglas W.

    2009-03-01

    Design and manufacturing of transparent armor have been historically carried out using experimental approaches. In this study, we use advanced computational modeling tools to perform virtual design evaluations of transparent armor systems under different projectile impact conditions. AHPCRC developed modeling software EPIC’06 [1] is used in predicting the penetration resistance of transparent armor systems. LaGrangian-based finite element analyses combined with particle dynamics are used to simulate the damage initiation and propagation process for the armor system under impact conditions. It is found that a 1-parameter single state model can be used to predict the impact penetration depth with relatively good accuracy, suggesting that the finely comminuted glass particles follow the behavior similar to a viscous fluid. Even though the intact strength of borosilicate and soda lime glass are different, the same fractured strength can be used for both glasses to capture the penetration depth.

  13. Numerical Investigation on the High-Speed Water-Entry Behaviors of Cylindrical, Hemispherical and Conical Projectiles

    NASA Astrophysics Data System (ADS)

    Guo, Zi-Tao; Zhang, Wei; Xiao, Xin-Ke

    2009-06-01

    The water entry problem is considered as a classic problem which has a research history of more than 70 years, the water-entry process for projectiles with different nose will be significant for related application and experimental design. In this paper, a series of numerical simulations were conducted to study the water-entry behaviors of cylindrical, hemispherical and conical projectiles using the coupled Lagrange-Euler technology in hydro-code AUTODYN-2D. The detailed cavity expansion process and the cavity characteristics of three projectiles in the early stages of water-entry were obtained. The effects of the projectile nose shape and the projectile velocity on the cavity shapes were studied. Simultaneously, the laws of velocity attenuations for three projectiles were also proposed in this study. The results show that the influence of the projectile velocity on the cavity thickness is much larger than that of the projectile nose shapes, but compared with the effect on the cavity length, the nose shape influence shows little difference with that of the impact velocity. For an identical initial projectile velocity, the cylindrical projectile decays the fastest underwater followed by conical projectiles and hemispherical projectiles.

  14. Exploring pulse shaping for Z using graded-density impactors on gas guns (final report for LDRD project 79879).

    SciTech Connect

    Furnish, Michael David; Reinhart, William Dodd; Anderson, William W. (Los Alamos National Laboratory, Los Alamos, NM); Vogler, Tracy John; Hixson, Rob (Los Alamos National Laboratory, Los Alamos, NM); Kipp, Marlin E.

    2005-10-01

    While isentropic compression experiment (ICE) techniques have proved useful in deducing the high-pressure compressibility of a wide range of materials, they have encountered difficulties where large-volume phase transitions exist. The present study sought to apply graded-density impactor methods for producing isentropic loading to planar impact experiments to selected such problems. Cerium was chosen due to its 20% compression between 0.7 and 1.0 GPa. A model was constructed based on limited earlier dynamic data, and applied to the design of a suite of experiments. A capability for handling this material was installed. Two experiments were executed using shock/reload techniques with available samples, loading initially to near the gamma-alpha transition, then reloading. As well, two graded-density impactor experiments were conducted with alumina. A method for interpreting ICE data was developed and validated; this uses a wavelet construction for the ramp wave and includes corrections for the ''diffraction'' of wavelets by releases or reloads reflected from the sample/window interface. Alternate methods for constructing graded-density impactors are discussed.

  15. Gas Dynamics, Characterization, and Calibration of Fast Flow Flight Cascade Impactor Quartz Crystal Microbalances (QCM) for Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Grant, J.R.; Thorpe, A. N.; James, C.; Michael, A.; Ware, M.; Senftle, F.; Smith, S.

    1997-01-01

    During recent high altitude flights, we have tested the aerosol section of the fast flow flight cascade impactor quartz crystal microbalance (QCM) on loan to Howard University from NASA. The aerosol mass collected during these flights was disappointingly small. Increasing the flow through the QCM did not correct the problem. It was clear that the instrument was not being operated under proper conditions for aerosol collect ion primarily because the gas dynamics is not well understood. A laboratory study was therefore undertaken using two different fast flow QCM's in an attempt to establish the gas flow characteristics of the aerosol sections and its effect on particle collection, Some tests were made at low temperatures but most of the work reported here was carried out at room temperature. The QCM is a cascade type impactor originally designed by May (1945) and later modified by Anderson (1966) and Mercer et al (1970) for chemical gas analysis. The QCM has been used extensively for collecting and sizing stratospheric aerosol particles. In this paper all flow rates are given or corrected and referred to in terms of air at STP. All of the flow meters were kept at STP. Although there have been several calibration and evaluation studies of moderate flow cascade impactors of less than or equal to 1 L/rein., there is little experimental information on the gas flow characteristics for fast flow rates greater than 1 L/rein.

  16. Constraints on the pre-impact orbits of Theia, the Borealis impactor and the progenitor of Mercury

    NASA Astrophysics Data System (ADS)

    Jackson, Alan P.; Gabriel, Travis; Asphaug, Erik

    2016-10-01

    Many aspects of the current dynamical and compositional configuration of the inner Solar System, such as Mercury's large core mass fraction, the angular momentum of the Earth-Moon system, and the reorientation of Mars, have been achieved through the effects of giant impacts. It is possible to relate the impact conditions, especially the velocity, to the pre-impact orbits. This in turn provides insight into the source regions for the terrestrial planets for comparison with N-body accretion models. For example, in the case of the canonical model for the formation of the Moon, previous studies have investigated regions in which the Mars-size impactor, Theia, could be quasi-stable for millions of years. We can however obtain constraints on the orbit of an impactor immediately prior to collision simply by knowing the impact velocity. We consider the canonical Moon formation model, as well as the models of Cuk & Stewart (2012), Canup (2012) and Reufer et al. (2012), to derive from each model its constraints on the pre-impact orbit of Theia. We also consider Mars, and provide constraints on the pre-impact orbit of the impactor suggested to have formed the Borealis basin, and Mercury, namely the Benz et al. (2007) scenario for the formation of Mercury. We discuss the implication of these pre-impact orbits for the origin of the bodies and their compositions.

  17. Techniques for Transition and Surface Temperature Measurements on Projectiles at Hypersonic Velocities- A Status Report

    NASA Technical Reports Server (NTRS)

    Wilder, M. C.; Bogdanoff, D. W.

    2005-01-01

    A research effort to advance techniques for determining transition location and measuring surface temperatures on graphite-tipped projectiles in hypersonic flight in a ballistic range is described. Projectiles were launched at muzzle velocities of approx. 4.7 km/sec into air at pressures of 190-570 Torr. Most launches had maximum pitch and yaw angles of 2.5-5 degrees at pressures of 380 Torr and above and 3-6 degrees at pressures of 190-380 Torr. Arcjet-ablated and machined, bead-blasted projectiles were launched; special cleaning techniques had to be developed for the latter class of projectiles. Improved methods of using helium to remove the radiating gas cap around the projectiles at the locations where ICCD (intensified charge coupled device) camera images were taken are described. Two ICCD cameras with a wavelength sensitivity range of 480-870 nm have been used in this program for several years to obtain images. In the last year, a third camera, with a wavelength sensitivity range of 1.5-5 microns [in the infrared (IR)], has been added. ICCD and IR camera images of hemisphere nose and 70 degree sphere-cone nose projectiles at velocities of 4.0-4.7 km/sec are presented. The ICCD images clearly show a region of steep temperature rise indicative of transition from laminar to turbulent flow. Preliminary temperature data for the graphite projectile noses are presented.

  18. Non-Invasive Timing of Gas Gun Projectiles with Light Detection and Ranging

    NASA Astrophysics Data System (ADS)

    Goodwin, Peter; Wu, Ming; Dattelbaum, Dana

    2013-06-01

    We have developed a Light Detection and Ranging (LIDAR) diagnostic to track the position of a projectile inside of the gas gun barrel in real-time. This capability permits the generation of precisely timed trigger pulses useful for pre-triggering high-latency diagnostics such as a flash lamp-pumped laser. An initial feasibility test was performed using a 72 mm bore single-stage gas gun routinely used for dynamic research at Los Alamos National Laboratory. A 655-nm pulsed (~100 ps) diode laser operating at a pulse repetition rate of ~100 kHz was used to interrogate the position of the moving projectile in real-time. The position of the projectile in the gun barrel was tracked over a distance of ~3 meters prior to impact. The position record showed that the projectile moved at a constant velocity (483 m/s) prior to impacting the target. This velocity was in good agreement with independent measurements of the projectile velocity by photon Doppler velocimetry, and timing of the passage of the projectile through optical marker beams positioned at the muzzle of the gun. The LIDAR return can be processed in real-time to generate pre-trigger pulses at preset separations between the projectile and target. Work funded by LANL Laboratory Directed Research Project 2011012DR. LA-UR-13-21121, approved for public release.

  19. Non-invasive timing of gas gun projectiles with light detection and ranging

    NASA Astrophysics Data System (ADS)

    Goodwin, P. M.; Bartram, B. D.; Gibson, L. L.; Wu, M.; Dattelbaum, D. M.

    2014-05-01

    We have developed a Light Detection and Ranging (LIDAR) diagnostic to track the position of a projectile inside of a gas gun launch tube in real-time. This capability permits the generation of precisely timed trigger pulses useful for triggering high-latency diagnostics such as a flash lamp-pumped laser. An initial feasibility test was performed using a 72 mm bore diameter single-stage gas gun routinely used for dynamic research at Los Alamos. A 655 nm pulsed diode laser operating at a pulse repetition rate of 100 kHz was used to interrogate the position of the moving projectile in real-time. The position of the projectile in the gun barrel was tracked over a distance of ~ 3 meters prior to impact. The position record showed that the projectile moved at a velocity of 489 m/s prior to impacting the target. This velocity was in good agreement with independent measurements of the projectile velocity by photon Doppler velocimetry and timing of the passage of the projectile through optical marker beams positioned at the muzzle of the gun. The time-to-amplitude conversion electronics used enable the LIDAR data to be processed in real-time to generate trigger pulses at preset separations between the projectile and target.

  20. Size-separated sampling and analysis of isocyanates in workplace aerosols. Part I. Denuder--cascade impactor sampler.

    PubMed

    Dahlin, Jakob; Spanne, Mårten; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2008-07-01

    Isocyanates in the workplace atmosphere are typically present both in gas and particle phase. The health effects of exposure to isocyanates in gas phase and different particle size fractions are likely to be different due to their ability to reach different parts in the respiratory system. To reveal more details regarding the exposure to isocyanate aerosols, a denuder-impactor (DI) sampler for airborne isocyanates was designed. The sampler consists of a channel-plate denuder for collection of gaseous isocyanates, in series with three-cascade impactor stages with cut-off diameters (d(50)) of 2.5, 1.0 and 0.5 mum. An end filter was connected in series after the impactor for collection of particles smaller than 0.5 mum. The denuder, impactor plates and the end filter were impregnated with a mixture of di-n-butylamine (DBA) and acetic acid for derivatization of the isocyanates. During sampling, the reagent on the impactor plates and the end filter is continuously refreshed, due to the DBA release from the impregnated denuder plates. This secures efficient derivatization of all isocyanate particles. The airflow through the sampler was 5 l min(-1). After sampling, the samples containing the different size fractions were analyzed using liquid chromatography-mass spectrometry (LC-MS)/MS. The DBA impregnation was stable in the sampler for at least 1 week. After sampling, the DBA derivatives were stable for at least 3 weeks. Air sampling was performed in a test chamber (300 l). Isocyanate aerosols studied were thermal degradation products of different polyurethane polymers, spraying of isocyanate coating compounds and pure gas-phase isocyanates. Sampling with impinger flasks, containing DBA in toluene, with a glass fiber filter in series was used as a reference method. The DI sampler showed good compliance with the reference method, regarding total air levels. For the different aerosols studied, vast differences were revealed in the distribution of isocyanate in gas and

  1. Dressed projectile charge state dependence of differential electron emission from Ne atom

    NASA Astrophysics Data System (ADS)

    Biswas, S.; Monti, J. M.; Rivarola, R. D.; Tribedi, L. C.

    2015-01-01

    We study the projectile charge state dependence of doubly differential electron emission cross section (DDCS) in ionization of Ne under the impact of dressed and bare oxygen ions. Experimental DDCS results measured at different angles are compared with the calculations based on a CDW-EIS approximation using the GSZ model potential to describe projectile active-electron interaction. This prescription gives an overall very good agreement. In general a deviation from the q2-law was observed in the DDCS. The observations crudely identify the dominance of different projectile electron loss mechanisms at certain electron energy range.

  2. Measurement of the summed residual projectile mass in relativistic heavy-ion collisions

    SciTech Connect

    Stevenson, J.D.; Martinis, J.; Price, P.B.

    1981-10-05

    Measurements of the summed mass of projectile fragments, M/sub s/ = summationM/sub pf/, are reported for 2.1-GeV/nucleon /sup 20/Ne+C and /sup 20/Ne+Mo. Unlike previous measurements of cross sections for individual projectile fragments, these measurements are quite sensitive to the size of the target nucleus. The distribution of summed residual projectile mass, M/sub s/, provides the first conclusive evidence of the validity of the geometrical ''abrasion'' model of relativistic heavy-ion collisions.

  3. Projectile motion on an inclined misty surface: I. Capturing and analysing the trajectory

    NASA Astrophysics Data System (ADS)

    Ho, S. Y.; Foong, S. K.; Lim, C. H.; Lim, C. C.; Lin, K.; Kuppan, L.

    2009-05-01

    Projectile motion is usually the first non-uniform two-dimensional motion that students will encounter in a pre-university physics course. In this article, we introduce a novel technique for capturing the trajectory of projectile motion on an inclined Perspex plane. This is achieved by coating the Perspex with a thin layer of fine water droplets that allows the projectile to leave a trail as it passes. The experiment was field-tested in Singapore and the response was very good.

  4. Projectile motion in real-life situation: Kinematics of basketball shooting

    NASA Astrophysics Data System (ADS)

    Changjan, A.; Mueanploy, W.

    2015-06-01

    Basketball shooting is a basic practice for players. The path of the ball from the players to the hoop is projectile motion. For undergraduate introductory physics courses student must be taught about projectile motion. Basketball shooting can be used as a case study for learning projectile motion from real-life situation. In this research, we discuss the relationship between optimal angle, minimum initial velocity and the height of the ball before the player shoots the ball for basketball shooting problem analytically. We found that the value of optimal angle and minimum initial velocity decreases with increasing the height of the ball before the player shoots the ball.

  5. Cavity dynamics and particle alignment in the wake of a supersonic projectile penetrating a dusty plasma

    SciTech Connect

    Arp, O.; Caliebe, D.; Piel, A.

    2011-06-15

    The penetration of a projectile into a strongly coupled dusty plasma was studied in a radio-frequency discharge under microgravity conditions. A supersonic projectile produces an elongated dust-free cavity in its wake. The dynamics of the cavity is analyzed and compared with Langevin dynamics simulations. Besides a three-dimensional Mach cone structure, the simulation shows that the cavity dynamics can be subdivided into three phases: An opening phase with fixed time scale, a closing phase, whose duration is affected by the projectile speed and, finally, a phase of particle realignment in the target cloud, which persists for a long time after the closure of the cavity.

  6. Cavity dynamics and particle alignment in the wake of a supersonic projectile penetrating a dusty plasma

    NASA Astrophysics Data System (ADS)

    Arp, O.; Caliebe, D.; Piel, A.

    2011-06-01

    The penetration of a projectile into a strongly coupled dusty plasma was studied in a radio-frequency discharge under microgravity conditions. A supersonic projectile produces an elongated dust-free cavity in its wake. The dynamics of the cavity is analyzed and compared with Langevin dynamics simulations. Besides a three-dimensional Mach cone structure, the simulation shows that the cavity dynamics can be subdivided into three phases: An opening phase with fixed time scale, a closing phase, whose duration is affected by the projectile speed and, finally, a phase of particle realignment in the target cloud, which persists for a long time after the closure of the cavity.

  7. Optimization of a counterflow virtual impactor (CVI) for studying aerosol effects on cloud droplet number

    SciTech Connect

    Anderson, T.L.

    1992-01-01

    This dissertation considers the problem of collecting cloud droplets in order to study the relatioship between droplet-nucleating particles and cloud droplet number concentration. Aerosol-induced modulation of cloud droplet number is potentially significant to global climate. The key activity was optimization of a Counterflow Virtual Impactor (CVI) for performing the cloud droplet collection. This involved numerical modeling of the collection process, construction and calibration of a new version of the CVI,and deployment of the new CVI in a field experiment. Numerical modeling revealed, with one cavent, that CVI measurements will not be significantly distorted either by droplet evaporation ahead of the collection plane or by droplet collisions during collection. The cavent is that if large (drizzle-size) droplets shatter upon collisions with smaller droplets, the measurement of droplet number could be distorted upwards. Laboratory calibration activities showed the new version to perform its size selection as predicted by theory and to have excellent cut sharpness. In addition, evidence of droplet shattering in the presence of large droplets was obtained. Thus, both laboratory and modeling evidence regarding large droplets lead to the suggestion that these be excluded from the inlet in field applications. The field experiment studying coastal stratiform clouds showed the CVI to perform well and to provide a large and unique data set relevant to examining the relationship between aerosol loading (number or volume) and cloud droplet number. Key resutls were (1) the majority of cloud droplet residue particles were smaller than one-tenth micrometer (diameter) in both clean and continentally influenced conditions, (2) total particle number variations were not correlated to cloud droplet number variations on any time scale, and (3) dominant sources of cloud variation, which tended to obscure the detection of aerosol effects, were meterology and cloud patchiness.

  8. Improvement of multi jet low pressure impactor for high collection efficiency of UF5 in the molecular laser isotope separation of uranium

    NASA Astrophysics Data System (ADS)

    Kuga, Yoshikazu; Jurcik, Benjamin; Satooka, Sakae; Takeuchi, Kazuo

    1995-07-01

    A numerical and experimental study for the collection of photo-produced UF 5 particles was performed for the low pressure impactors which have different design factors at typical flow conditions (upstream pressure of the impactor = 10-15 Torr, pressure ratio of downstream to upstream of the impactor, {P down}/{P up} = 0.2-0.5 ) in the molecular laser isotope separation of uranium at RIKEN (RIMLIS). Smaller {H}/{W} ratios (the distance between the impactor orifice exit and the impaction plate, H, divided by the orifice diameter of the impactor, W) and the smaller {P down}/{P up} were found to be preferable to obtain a higher collection efficiency from both numerical and experimental investigations. In addition it was experimentally demonstrated that the use of a 16 μm laser system for the selective reaction of 235UF 6 to form 235UF 5 was not relevant for the study of the collection of UF 5 particles. So, we used an ultraviolet laser system (fourth harmonic YAG laser (266 nm) and an excimer laser (KrF, 248 nm)) which was more convenient to cope with various operating conditions. The collection efficiency was found to increase with the initial concentration of UF 5 molecules produced. Applying the improved impactor stage, we obtained a collection efficiency which was approximately 10 times higher than that of our previous work. Higher collection efficiencies of photo-produced UF 5 particles enriched in 235U reduce the enrichment cost.

  9. Electric Solar Wind Sail Kinetic Energy Impactor for Asteroid Deflection Missions

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Kouhei; Yamakawa, Hiroshi

    2016-03-01

    An electric solar wind sail uses the natural solar wind stream to produce low but continuous thrust by interacting with a number of long thin charged tethers. It allows a spacecraft to generate a thrust without consuming any reaction mass. The aim of this paper is to investigate the use of a spacecraft with such a propulsion system to deflect an asteroid with a high relative velocity away from an Earth collision trajectory. To this end, we formulate a simulation model for the electric solar wind sail. By summing thrust vectors exerted on each tether, a dynamic model which gives the relation between the thrust and sail attitude is proposed. Orbital maneuvering by fixing the sail's attitude and changing tether voltage is considered. A detailed study of the deflection of fictional asteroids, which are assumed to be identified 15 years before Earth impact, is also presented. Assuming a spacecraft characteristic acceleration of 0.5 mm/s 2, and a projectile mass of 1,000 kg, we show that the trajectory of asteroids with one million tons can be changed enough to avoid a collision with the Earth. Finally, the effectiveness of using this method of propulsion in an asteroid deflection mission is evaluated in comparison with using flat photonic solar sails.

  10. A Gas-Actuated Projectile Launcher for High-Energy Impact Testing of Structures

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Jaunky, Navin; Lawson, Robin E.; Knight, Norman F., Jr.; Lyle, Karen H.

    1999-01-01

    A gas-act,uated penetration device has been developed for high-energy impact testing of structures. The high-energy impact. t,estiiig is for experimental simulation of uncontained engine failures. The non-linear transient finite element, code LS-DYNA3D has been used in the numerical simula.tions of a titanium rectangular blade with a.n aluminum target, plate. Threshold velocities for different combinations of pitch and yaw angles of the impactor were obtained for the impactor-target, t8est configuration in the numerica.1 simulations. Complet,e penet,ration of the target plate was also simulat,ed numerically. Finally, limited comparison of analytical and experimental results is presented for complete penetration of the target by the impactor.

  11. Measurement of angular distribution of sound emission from training projectiles in subsonic flight

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Parthasarathy, S. P.; Harstad, K. G.; Back, L. H.

    1986-01-01

    Training projectiles with nose ring cavities that produce intense whistles in stationary free-jet tests were shot in a relatively straight-line trajectory. A ground based microphone was used to obtain the angular distribution of sound intensity produced from the subsonically flying projectile. Data reduction required calculation of Doppler and attenuation factors which were determined based on a non-linear trajectory. Also, the directional sensitivity of the microphone was measured and used in the data reduction. Significant angular variation of sound intensity produced from the projectile was found which can be used to plot an intensity contour map on the ground. A full-scale field test confirmed the validity of the aeroacoustic concept of producing a relatively intense whistle from the projectile, and the usefulness of a real-time data acquisition system.

  12. Projectile containing metastable intermolecular composites and spot fire method of use

    DOEpatents

    Asay, Blaine W.; Son, Steven F.; Sanders, V. Eric; Foley, Timothy; Novak, Alan M.; Busse, James R.

    2012-07-31

    A method for altering the course of a conflagration involving firing a projectile comprising a powder mixture of oxidant powder and nanosized reductant powder at velocity sufficient for a violent reaction between the oxidant powder and the nanosized reductant powder upon impact of the projectile, and causing impact of the projectile at a location chosen to draw a main fire to a spot fire at such location and thereby change the course of the conflagration, whereby the air near the chosen location is heated to a temperature sufficient to cause a spot fire at such location. The invention also includes a projectile useful for such method and said mixture preferably comprises a metastable intermolecular composite.

  13. A model for water-entry projectile with an open cavity

    NASA Astrophysics Data System (ADS)

    Zou, W.; Liu, H.

    2015-12-01

    Study on dynamics of a projectile running with a cavity in the process of water entry closely relates to the development of new generation of air-to-water vehicle. It becomes a key concern to develop a flexible model of the high-speed water-entry projectile. The projectile is modelled using the unsteady cavity model from Serebryakov in the frame of the rigid-body dynamics theory. Based on the model, without loss of generality, oblique water-entry projectile running with an open cavity is simulated, and numerical results are in good agreement with measured data available. The model proves effective and has a great potential to investigate ballistics of an air-dropped vehicle at the early stage of water entry.

  14. Projectile shape and material effects in hypervelocity impact response of dual-wall structures

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Darzi, Kent

    1992-01-01

    All large spacecraft are susceptible to impacts by meteoroids and pieces of orbiting space debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. A long-duration spacecraft developed for a mission into this environment must include adequate protection against perforation of pressurized components by such impacts. This paper presents the results of an investigation into the effects of projectile shape and material on the perforation of aluminum dual-wall structural systems. Impact damage is characterized according to the extent of perforation, crater, and spall damage in the structural systems as a result of hypervelocity projectile impact loadings. Analysis of the damage data shows that there are distinct differences in impact damage from cylindrical and spherical projectiles. Projectile density is also found to affect the type and extent of damage sustained by dual-wall structural systems.

  15. Target-projectile interaction during impact melting at Kamil Crater, Egypt

    NASA Astrophysics Data System (ADS)

    Fazio, Agnese; D'Orazio, Massimo; Cordier, Carole; Folco, Luigi

    2016-05-01

    In small meteorite impacts, the projectile may survive through fragmentation; in addition, it may melt, and chemically and physically interact with both shocked and melted target rocks. However, the mixing/mingling between projectile and target melts is a process still not completely understood. Kamil Crater (45 m in diameter; Egypt), generated by the hypervelocity impact of the Gebel Kamil Ni-rich ataxite on sandstone target, allows to study the target-projectile interaction in a simple and fresh geological setting. We conducted a petrographic and geochemical study of macroscopic impact melt lapilli and bombs ejected from the crater, which were collected during our geophysical campaign in February 2010. Two types of glasses constitute the impact melt lapilli and bombs: a white glass and a dark glass. The white glass is mostly made of SiO2 and it is devoid of inclusions. Its negligible Ni and Co contents suggest derivation from the target rocks without interaction with the projectile (<0.1 wt% of projectile contamination). The dark glass is a silicate melt with variable contents of Al2O3 (0.84-18.7 wt%), FeOT (1.83-61.5 wt%), and NiO (<0.01-10.2 wt%). The dark glass typically includes fragments (from few μm to several mm in size) of shocked sandstone, diaplectic glass, lechatelierite, and Ni-Fe metal blebs. The metal blebs are enriched in Ni compared to the Gebel Kamil meteorite. The dark glass is thus a mixture of target and projectile melts (11-12 wt% of projectile contamination). Based on recently proposed models for target-projectile interaction and for impact glass formation, we suggest a scenario for the glass formation at Kamil. During the transition from the contact and compression stage and the excavation stage, projectile and target liquids formed at their interface and chemically interact in a restricted zone. Projectile contamination affected only a shallow portion of the target rocks. The SiO2 melt that eventually solidified as white glass behaved as

  16. Development of odd-Z-projectile reactions for transactinide element synthesis

    SciTech Connect

    Folden III, Charles Marvin

    2004-11-04

    The development of new odd-Z-projectile reactions leading to the production of transactinide elements is described. The cross section of the even-Z-projectile 208Pb(64Ni, n)271Ds reaction was measured at two new energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, seven decay chains attributable to 271Ds were observed. These data, combined with previous results, establish an excitation function for the production of 271Ds. The maximum cross section was 20 +15 -11 pb at a center-of-target energy of 311.5 MeV in the laboratory frame.The data from the 271Ds experiments were used to estimate the optimum beam energy for the new odd-Z-projectile 208Pb(65Cu, n)272-111 reaction using the Fusion by Diffusion theory proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski. A cross section for this reaction was measured for the first time, at a center-of-target energy of 321.1 MeV in the laboratory frame. The excitation energy f or compound nuclei formed at the target center was 13.2 MeV. One decay chain was observed, resulting in a measured cross section of 1.7 +3.9 -1.4 pb. This decay chain is in good agreement with previously published data on the decay of 272-111.The new odd-Z-projectile 208Pb(55Mn, n)262Bh reaction was studied at three different projectile energies, and 33 decay chains of 262Bh were observed. The existence of a previously reported alpha-decaying isomeric state in this nuclide was confirmed. Production of the ground state was preferred at all three beam energies. The maximum cross section was 540 +180 -150 pb at a projectile center-of-target energy of 264.0 MeV. This cross section is much larger than that previously reported for the even-Z-projectile 209Bi(54Cr, n)262Bh reaction, which may be because the 54Cr projectile energies in the latter reaction were too high for optimum production of the 1n product. At the highest projectile energy of 268.0 MeV in the target center, two decay

  17. Dissemination and fractionation of projectile materials in the impact melts from Wabar Crater, Saudi Arabia

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; See, Thomas H.; Hoerz, Friedrich

    1992-01-01

    Results are presented from the analyses of small ballistically dispersed melt samples (occurring in the form of aerodynamically shaped spheres, dumbbells, and teardrops) from the Wabar Crater (Saudi Arabia) and of melts from the Wabar and Nejed meteorites. On the basis of the data obtained and of models for crater forming processes it is concluded that the ballistically-dispersed glasses were formed from material at shallow levels in the target zone where temperatures were higher and where intimate physical contact with the disrupting impactor was achieved. Siderophile element fractionation was completed early, while the impactor was undergoing decompression and prior to mixing with the target glasses.

  18. Ballistic Impact of Braided Composites with a Soft Projectile

    NASA Technical Reports Server (NTRS)

    Roberts, Gary D.; Pereira, J. Michael; Revilock, Duane M., Jr.; Binienda, Wieslaw K.; Xie, Ming; Braley, Mike

    2002-01-01

    Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Failure modes were identified for aluminum plates and for composites plates and half-rings made from triaxial carbon fiber braid having a 0/+/- 60deg architecture. For aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate. For composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the +/-60deg fiber directions until triangular flaps opened to form a hole. For composite half-rings fabricated with 0deg fibers aligned circumferentially, fiber tensile failure also occurred in the back ply. Cracks first propagated from this site perpendicular the 0deg fibers. The cracks then turned to follow the +/-60deg fibers and 0deg fibers until rectangular flaps opened to form a hole. Damage in the composites was localized near the impact site, while cracks in the aluminum extended to the boundaries.

  19. Study of hypervelocity projectile impact on thick metal plates

    DOE PAGES

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; Hixson, Robert S.; Becker, Steven; Pena, Michael T.; Jennings, Richard; Somasoundaram, Deepak; Matthes, Melissa; Daykin, Edward P.; et al

    2016-01-01

    Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments:more » Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.« less

  20. Study of hypervelocity projectile impact on thick metal plates

    SciTech Connect

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; Hixson, Robert S.; Becker, Steven; Pena, Michael T.; Jennings, Richard; Somasoundaram, Deepak; Matthes, Melissa; Daykin, Edward P.; Machorro, Eric

    2016-01-01

    Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments: Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.

  1. Molecular depth profiling in ice matrices using C 60 projectiles

    NASA Astrophysics Data System (ADS)

    Wucher, A.; Sun, S.; Szakal, C.; Winograd, N.

    2004-06-01

    The prospects of molecular sputter depth profiling using C 60+ projectiles were investigated on thick ice layers prepared by freezing aqueous solutions of histamine onto a metal substrate. The samples were analyzed in a ToF-SIMS spectrometer equipped with a liquid metal Ga + ion source and a newly developed fullerene ion source. The C 60+ beam was used to erode the surface, while static ToF-SIMS spectra were taken with both ion beams alternatively between sputtering cycles. We find that the signals both related to the ice matrix and to the histamine are about two orders of magnitude higher under 20-keV C 60 than under 15-keV Ga bombardment. Histamine related molecular signals are found to increase drastically if the freshly introduced surface is pre-sputtered with C 60 ions, until at a total ion fluence of about 10 13 cm -2 the spectra are completely dominated by the molecular ion and characteristic fragments of histamine. At larger fluence, the signal is found to decrease with a disappearance cross section of approximately 10 -14 cm 2, until at total fluences of about 10 14 cm -2 a steady state with stable molecular signals is reached. In contrast, no appreciable molecular signal could be observed if Ga + ions were used to erode the surface.

  2. Non-lead, environmentally safe projectiles and method of making same

    DOEpatents

    Lowden, Richard A.; McCoig, Thomas M.; Dooley, Joseph B.

    2000-01-01

    A projectile, such as a bullet, is made by combining two different metals in proportions calculated to achieve a desired density, without using lead. A base constituent, made of a material having density greater than lead, is combined with a binder constituent having less density. The binder constituent is malleable and ductile metallic phase material that forms projectile shapes when subjected to a consolidation force, such as compression. The metal constituents can be selected, rationed, and consolidated to achieve desired frangibility characteristics.

  3. Non-lead, environmentally safe projectiles and method of making same

    DOEpatents

    Lowden, Richard A.; McCoig, Thomas M.; Dooley, Joseph B.

    1998-01-01

    A projectile, such as a bullet, is made by combining two different metals in proportions calculated to achieve a desired density, without using lead. A base constituent, made of a material having density greater than lead, is combined with a binder constituent having less density. The binder constituent is malleable and ductile metallic phase material that forms projectile shapes when subjected to a consolidation force, such as compression. The metal constituents can be selected, rationed, and consolidated to achieve desired frangibility characteristics.

  4. Non-lead environmentally safe projectiles and method of making same

    DOEpatents

    Lowden, Richard A.; McCoig, Thomas M.; Dooley, Joseph B.

    1999-01-01

    A projectile, such as a bullet, is made by combining two different metals in proportions calculated to achieve a desired density, without using lead. A base constituent, made of a material having density greater than lead, is combined with a binder constituent having less density. The binder constituent is malleable and ductile metallic base material that forms projectile shapes when subjected to a consolidation force, such as compression. The metal constituents can be selected, rationed, and consolidated to achieve desired frangibility characteristics.

  5. Effect of Projectile Materials on Foreign Object Damage of a Gas-Turbine Grade Silicon Nitride

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Racz, Zsolt; Bhatt, Ramakrishna T.; Brewer, David N.; Gyekenyesi, John P.

    2005-01-01

    Foreign object damage (FOD) behavior of AS800 silicon nitride was determined using four different projectile materials at ambient temperature. The target test specimens rigidly supported were impacted at their centers by spherical projectiles with a diameter of 1.59 mm. Four different types of projectiles were used including hardened steel balls, annealed steel balls, silicon nitride balls, and brass balls. Post-impact strength of each target specimen impacted was determined as a function of impact velocity to better understand the severity of local impact damage. The critical impact velocity where target specimens fail upon impact was highest with brass balls, lowest with ceramic ball, and intermediate with annealed and hardened steel balls. Degree of strength degradation upon impact followed the same order as in the critical impact velocity with respect to projectile materials. For steel balls, hardened projectiles yielded more significant impact damage than annealed counterparts. The most important material parameter affecting FOD was identified as hardness of projectiles and was correlated in terms of critical impact velocity, impact deformation, and impact load.

  6. Fragmentation of armor piercing steel projectiles upon oblique perforation of steel plates

    NASA Astrophysics Data System (ADS)

    Paris, V.; Weiss, A.; Vizel, A.; Ran, E.; Aizik, F.

    2012-08-01

    In this study, a constitutive strength and failure model for a steel core of a14.5 mm API projectile was developed. Dynamic response of a projectile steel core was described by the Johnson-Cook constitutive model combined with principal tensile stress spall model. In order to obtain the parameters required for numerical description of projectile core material behavior, a series of planar impact experiments was done. The parameters of the Johnson-Cook constitutive model were extracted by matching simulated and experimental velocity profiles of planar impact. A series of oblique ballistic experiments with x-ray monitoring was carried out to study the effect of obliquity angle and armor steel plate thickness on shattering behavior of the 14.5 mm API projectile. According to analysis of x-ray images the fragmentation level increases with both steel plate thickness and angle of inclination. The numerical modeling of the ballistic experiments was done using commercial finite element code, LS-DYNA. Dynamic response of high hardness (HH) armor steel was described using a modified Johnson-Cook strength and failure model. A series of simulations with various values of maximal principal tensile stress was run in order to capture the overall fracture behavior of the projectile's core. Reasonable agreement between simulated and x-ray failure pattern of projectile core has been observed.

  7. Ablation and deceleration of mass-driver launched projectiles for space disposal of nuclear wastes

    NASA Technical Reports Server (NTRS)

    Park, C.; Bowen, S. W.

    1981-01-01

    The energy cost of launching a projectile containing nuclear waste is two orders of magnitude lower with a mass driver than with a typical rocket system. A mass driver scheme will be feasible, however, only if ablation and deceleration are within certain tolerable limits. It is shown that if a hemisphere-cylinder-shaped projectile protected thermally with a graphite nose is launched vertically to attain a velocity of 17 km/sec at an altitude of 40 km, the mass loss from ablation during atmospheric flight will be less than 0.1 ton, provided the radius of the projectile is under 20 cm and the projectile's mass is of the order of 1 ton. The velocity loss from drag will vary from 0.4 to 30 km/sec, depending on the mass and radius of the projectile, the smaller velocity loss corresponding to large mass and small radius. Ablation is always within a tolerable range for schemes using a mass driver launcher to dispose of nuclear wastes outside the solar system. Deceleration can also be held in the tolerable range if the mass and diameter of the projectile are properly chosen.

  8. Pepper spray projectile/disperser for countering hostage and barricade situations

    NASA Astrophysics Data System (ADS)

    Kelly, Roy

    1997-01-01

    An improved less-than-lethal projectile for use in hostage, barricade and tactical assault situations has been developed. The projectile is launched from a standoff position and disperse the incapacitating agent oleoresin capsicum in the form of atomized droplets. A literature search followed by an experimental study were conducted of the mechanism of barrier defeat for various shaped projectiles against the targets of interest in this work: window glass, plasterboard and plywood. Some of the trade- offs between velocity, standoff, projectile shape and size, penetration, and residual energy were quantified. Analysis of the ballistic trajectory and recoil, together with calculations of he amount of pepper spray needed to incapacitate the occupants of a typical barricaded structure, indicated the suitability of using a fin stabilized projectile fired from a conventional 37 mm riot control gas gun. Two projectile designs were considered, manufactured and tested. The results of static tests to simulate target impact, together with live firing trials against a variety of targets, showed that rear ejection of the atomized spray was more reproducible and effective than nose ejection. The performance characteristics of the finalized design were investigated in trials using the standard barrier for testing barrier penetrating tear gas agents as defined by the National Institute of Justice.

  9. Aerodynamic characteristics of nebulized terbutaline sulphate using the Next Generation Impactor (NGI) and CEN method.

    PubMed

    Abdelrahim, Mohamed E; Chrystyn, Henry

    2009-03-01

    Characterization of the aerosolized dose emitted from a nebulized system can be determined using CEN (prEN13544-1) methodology and more recently with a Next Generation Impactor (NGI), but evaporative effects can influence the results. We have investigated these characteristics using different flows and cooling with the NGI and compared the results to the standard CEN method using two different nebulizer systems. The NGI was operated using flows of 15 and 30 L min(-1) at room (ROOM) temperature and immediately after cooling at 5 degrees C for 90 min (COLD). Two nebulizer systems, the Sidestream jet nebulizer (SIDE) and the Aeroneb Pro (AERO), were used to nebulize terbutaline sulphate respiratory solution. The CEN method was also used to provide the aerodynamic characteristics of the aerosolized dose from these two nebulizer systems. The mean (SD) mass median aerodynamic diameter (MMAD) using 15COLD, 15ROOM, 30COLD, 30ROOM, and CEN for AERO was 5.0(0.1), 4.1(0.3), 4.4(0.2), 2.0(0.3), and 3.0(1.1) microm, respectively, and 4.2(0.4), 2.6(0.4), 3.5(0.1), 1.7(0.1), and 3.2(0.3) microm for SIDE. The fine particle fraction (FPF), using the NGI, followed the expected trend associated with the corresponding MMAD values, ranging from 48.1 to 70.5% from AERO and 57.3 to 87.8% for SIDE. The mean FPF for AERO and SIDE using the CEN methodology was 72.5 and 63.6%. Overall there was a highly significant difference (p < 0.001) between the different operating conditions for the FPF and MMAD of both nebulizer systems. All methods revealed a significant difference between AERO and SIDE except CEN. Both nebulizer systems were prone to evaporation effects during in vitro testing. Cooling and using a slow flow minimizes evaporation effects with the NGI and should be adopted as the recommended compendial method. The CEN method provides different values to those of the NGI operating conditions and could not differentiate between the two nebulizers. PMID:19392586

  10. A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

    PubMed Central

    Lee, Jae H.T.; Streijger, Femke; Tigchelaar, Seth; Maloon, Michael; Liu, Jie; Tetzlaff, Wolfram; Kwon, Brian K.

    2012-01-01

    While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor. Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5° (animals rotated at 22.5°), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing. The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in

  11. Dynamical sequestration of the Moon-forming impactor in co-orbital resonance with Earth

    NASA Astrophysics Data System (ADS)

    Kortenkamp, Stephen J.; Hartmann, William K.

    2016-09-01

    Recent concerns about the giant impact hypothesis for the origin of the Moon, and an associated "isotope crisis" may be assuaged if the impactor was a local object that formed near Earth. We investigated a scenario that may meet this criterion, with protoplanets assumed to originate in 1:1 co-orbital resonance with Earth. Using N-body numerical simulations we explored the dynamical consequences of placing Mars-mass companions in various co-orbital configurations with a proto-Earth of 0.9 Earth-masses (M⊕). We modeled 162 different configurations, some with just the four terrestrial planets and others that included the four giant planets. In both the 4- and 8-planet models we found that a single Mars-mass companion typically remained a stable co-orbital of Earth for the entire 250 million year (Myr) duration of our simulations (59 of 68 unique simulations). In an effort to destabilize such a system we carried out an additional 94 simulations that included a second Mars-mass co-orbital companion. Even with two Mars-mass companions sharing Earth's orbit about two-thirds of these models (66) also remained stable for the entire 250 Myr duration of the simulations. Of the 28 2-companion models that eventually became unstable 24 impacts were observed between Earth and an escaping co-orbital companion. The average delay we observed for an impact of a Mars-mass companion with Earth was 102 Myr, and the longest delay was 221 Myr. In 40% of the 8-planet models that became unstable (10 out of 25) Earth collided with the nearly equal mass Venus to form a super-Earth (loosely defined here as mass ≥1.7 M⊕). These impacts were typically the final giant impact in the system and often occurred after Earth and/or Venus has accreted one or more of the other large objects. Several of the stable configurations involved unusual 3-planet hierarchical co-orbital systems.

  12. Effective dose scaling factors for use with uranium series cascade impactor data: a reassessment using the IMBA code.

    PubMed

    Kim, Kwang Pyo; Wu, Chang-Yu; Birky, Brian K; Bolch, Wesley E

    2006-10-01

    Air sampling with a multi-stage cascade impactor enables one to assess airborne radioactivity as a function of particle size, significantly enhancing the accuracy of the dose assessment. The application of cascade sampling data to inhalation dose assessments can require more computational effort if something other than a mono-sized distribution per impactor stage is to be considered. To overcome this limitation, Kim et al. (Health Phys 89:359-374; 2005) introduced the concept of an effective dose scaling factor SF(E) enabling one to consider more realistic impactor stage radioactivity distributions (uniform, linearly decreasing, or linearly increasing variations with particle size). The SF(E) is the ratio of the effective dose given under a uniform or linearly changing radioactivity distribution across the particle size interval to that given for a mono-sized radioactivity distribution for the same impactor stage. The latter approach can initially be used (which requires less computational effort) followed by a rescaling of the effective dose either upward or downward by the SF(E) value. In this earlier study, the LUDEP code was employed which utilizes the ICRP 66 human respiratory tract model along the radionuclide biokinetic models given in ICRP Publication 30. In the present study, inhalation dose coefficients and effective dose scaling factors were reexamined for several radionuclides of the (238)U series using the IMBA program, which employs more recent and physiologically realistic biokinetic models published by the ICRP. An update of the effective dose scaling factors is thus the primary focus of this study rather than an extensive inter-comparison of the IMBA and LUDEP codes. Inhalation dose coefficients calculated by the two programs differ by up to a factor of 5 for Type F (238)U and (234)U, but are within only 2% of each other for Type S radionuclides. The ICRP 69 biokinetic model of uranium predicts retention in bone and kidneys that is slightly higher

  13. Micro-abrasion package capture cell experiment on the trailing edge of LDEF: Impactor chemistry and whipple bumper shield efficiencies

    NASA Technical Reports Server (NTRS)

    Fitzgerald, Howard J.; Yano, Hajime

    1995-01-01

    Four of the eight available double layer microparticle capture cells, flown as the experiment A0023 on the trailing (West) face of LDEF, have been extensively studied. An investigation of the chemistry of impactors has been made using SEM/EDX techniques and the effectiveness of the capture cells as bumper shields has also been examined. Studies of these capture cells gave positive EDX results, with 53 percent of impact sites indicating the presence of some chemical residues, the predominant residue identified as being silicon in varying quantities.

  14. Granulocyte-Colony Stimulating Factor (G-CSF) Improves Motor Recovery in the Rat Impactor Model for Spinal Cord Injury

    PubMed Central

    Dittgen, Tanjew; Pitzer, Claudia; Plaas, Christian; Kirsch, Friederike; Vogt, Gerhard; Laage, Rico; Schneider, Armin

    2012-01-01

    Granulocyte-colony stimulating factor (G-CSF) improves outcome after experimental SCI by counteracting apoptosis, and enhancing connectivity in the injured spinal cord. Previously we have employed the mouse hemisection SCI model and studied motor function after subcutaneous or transgenic delivery of the protein. To further broaden confidence in animal efficacy data we sought to determine efficacy in a different model and a different species. Here we investigated the effects of G-CSF in Wistar rats using the New York University Impactor. In this model, corroborating our previous data, rats treated subcutaneously with G-CSF over 2 weeks show significant improvement of motor function. PMID:22253813

  15. Transition from fractal cracking to fragmentation due to projectile penetration

    NASA Astrophysics Data System (ADS)

    Kun, F.; Halász, Z.

    2014-12-01

    We present a theoretical study of the fracture of two-dimensional disc-shaped samples due to the penetration of a projectile focusing on the dynamics of fracturing and on the geometrical structure of the generated crack pattern. The penetration of a cone is simulated into a plate of circular shape using a discrete element model of heterogeneous brittle materials varying the speed of penetration in a broad range. As the cone penetrates a destroyed zone is created from which cracks run to the external boundary of the plate. Computer simulations revealed that in the low speed limit of loading two cracks are generated with nearly straight shape. Increasing the penetration speed the crack pattern remains regular, however, both the number of cracks and their fractal dimension increases. High speed penetration gives rise to a crack network such that the sample gets fragmented into a large number of pieces. We give a quantitative analysis of the evolution of the system from simple cracking through fractal cracks to fragmentation with a connected crack network. Simulations showed that in the low speed limit of loading the growing cracks proceed in discrete jumps separated by periods when the crack tips are pinned. The statistics of the size of jumps and of the waitng times shows scale free behaviour, i.e. power law distributions are obtained with universal exponents. Dependence on the loading speed was pointed out only for the cutoffs of the distributions. In the high speed limit of loading the sample falls apart forming a large number of fragments. The size of fragments proved to be power law distributed where dependence on the loading speed is observed only for the cutoffs. The value of the exponent has good agreement with experiments.

  16. Meso-scale hypervelocity cratering experiments (MEMIN project): Characterization of projectile material

    NASA Astrophysics Data System (ADS)

    Domke, Isabelle; Deutsch, Alex; Hecht, Lutz; Kenkmann, Thomas; Berndt, Jasper

    2010-05-01

    The DFG-funded "MEMIN" (multidisciplinary experimental and modelling impact crater research network) research group is aimed at a better understanding of the impact cratering process by combining (i) numerical modelling of crater formation, (ii) investigation of terrestrial craters and (iii) meso-scale hypervelocity impact experiments using the large two-stage light gas gun at the Ernst-Mach-Institute (EMI; Efringen-Kirchen, Germany). In the framework of MEMIN, 1 cm-sized projectiles of the steel SAE 4130 (mass of 4.1 g) have been fired with a velocity of ~ 5.3 km s-1 onto blocks of Seeberger sandstone (size 100 x 100 x 50 cm, grain size 169+/-8 μm; porosity 12-20 vol.%). One goal of MEMIN is to document, analyze, and understand the fate of the projectile and its distribution between crater and ejecta; hence, the use of well-analyzed projectile material is mandatory. For this purpose, we use optical, and electron microscopy, electron microprobe (WWU, and MfN), and LA-ICP-MS microanalysis (WWU). Currently we evaluate which steel or iron meteorite is adequate for the intended use. Important properties of a projectile are (i) textural and chemical homogeneity, (ii) clear chemical distinction to the target sandstone, (iii) presence of elements such as Co, Ni, Cr, PGE that as "meteoritic component" are used in terrestrial craters to trace projectile matter, and characterize the type of the projectile (i.e., meteorite group), and finally (iv) mechanical properties that guarantee stability during sphere production, launch and flight. Strong chemical differences to the target material and geochemical homogeneity of the projectile will allow detection of small volumes of projectile matter by high spatial resolution in-situ analysis with the LA-ICP-MS. Steel SAE 4130 is heterogeneous at the 100-µm scale and has low trace element contents. In future, we plan the use of the alloyed heat treatable steel D290-1 as projectile as its texture is quite homogenous at the scale of

  17. Application of the modified chi-square ratio statistic in a stepwise procedure for cascade impactor equivalence testing.

    PubMed

    Weber, Benjamin; Lee, Sau L; Delvadia, Renishkumar; Lionberger, Robert; Li, Bing V; Tsong, Yi; Hochhaus, Guenther

    2015-03-01

    Equivalence testing of aerodynamic particle size distribution (APSD) through multi-stage cascade impactors (CIs) is important for establishing bioequivalence of orally inhaled drug products. Recent work demonstrated that the median of the modified chi-square ratio statistic (MmCSRS) is a promising metric for APSD equivalence testing of test (T) and reference (R) products as it can be applied to a reduced number of CI sites that are more relevant for lung deposition. This metric is also less sensitive to the increased variability often observed for low-deposition sites. A method to establish critical values for the MmCSRS is described here. This method considers the variability of the R product by employing a reference variance scaling approach that allows definition of critical values as a function of the observed variability of the R product. A stepwise CI equivalence test is proposed that integrates the MmCSRS as a method for comparing the relative shapes of CI profiles and incorporates statistical tests for assessing equivalence of single actuation content and impactor sized mass. This stepwise CI equivalence test was applied to 55 published CI profile scenarios, which were classified as equivalent or inequivalent by members of the Product Quality Research Institute working group (PQRI WG). The results of the stepwise CI equivalence test using a 25% difference in MmCSRS as an acceptance criterion provided the best matching with those of the PQRI WG as decisions of both methods agreed in 75% of the 55 CI profile scenarios.

  18. Numerical Study on the High-Speed Water-Entry Behaviors of Cylindrical, Hemispherical and Conical Projectiles

    NASA Astrophysics Data System (ADS)

    Guo, Zitao; Zhang, Wei; Luan, Shuping; Xiao, Xinke

    2009-12-01

    The water entry problem is considered as a classic problem which has a research history of more than 70 years, the water-entry process for projectiles with different nose will be significant for related application and experimental design. In this paper, a series of numerical simulations were conducted to study the water-entry behaviors of cylindrical, hemispherical and conical projectiles using the coupled Lagrange-Euler technology in the non-linear finite element code AUTODYN-2D. The detailed cavity expansion process and the cavity characteristics of three projectiles in the early stages of water-entry were obtained. The effects of the projectile nose shape and the projectile velocity on the cavity shapes were studied. Simultaneously, the laws of velocity attenuations for three projectiles were also proposed in this study. The results show that cylindrical projectile has the minimum ratio of the cavity length to the cavity half thickness among the three projectiles when they have identical impact velocities and the smoothed nose shape of projectiles can help reduce the water resistance, thus slowing down the velocity attenuations.

  19. Chemical projectile-target interaction during hypervelocity cratering experiments (MEMIN project).

    NASA Astrophysics Data System (ADS)

    Ebert, M.; Hecht, L.; Deutsch, A.; Kenkmann, T.

    2012-04-01

    The detection and identification of meteoritic components in impact-derived rocks are of great value for confirming an impact origin and reconstructing the type of extraterrestrial material that repeatedly stroke the Earth during geologic evolution [1]. However, little is known about processes that control the projectile distribution into the various impactites that originate during the cratering and excavation process, and inter-element fractionation between siderophile elements during impact cratering. In the context of the MEMIN project, cratering experiments have been performed using spheres of Cr-V-Co-Mo-W-rich steel and of the iron meteorite Campo del Cielo (IAB) as projectiles accelerated to about 5 km/s, and blocks of Seeberger sandstone as target. The experiments were carried out at the two-stage acceleration facilities of the Fraunhofer Ernst-Mach-Institute (Freiburg). Our results are based on geochemical analyses of highly shocked ejecta material. The ejecta show various shock features including multiple sets of planar deformations features (PDF) in quartz, diaplectic quartz, and partial melting of the sandstone. Melting is concentrated in the phyllosilicate-bearing sandstone matrix but involves quartz, too. Droplets of molten projectile have entered the low-viscosity sandstone melt but not quartz glass. Silica-rich sandstone melts are enriched in the elements that are used to trace the projectile, like Fe, Ni, Cr, Co, and V (but no or little W and Mo). Inter-element ratios of these "projectile" tracer elements within the contaminated sandstone melt may be strongly modified from the original ratios in the projectiles. This fractionation most likely result from variation in the lithophile or siderophile character and/or from differences in reactivity of these tracer elements with oxygen [2] during interaction of metal melt with silicate melt. The shocked quartz with PDF is also enriched in Fe and Ni (experiment with a meteorite iron projectile) and in Fe

  20. Hydrocode Simulation with Modified Johnson-Cook Model and Experimental Analysis of Explosively Formed Projectiles

    NASA Astrophysics Data System (ADS)

    Hussain, G.; Hameed, A.; Hetherington, J. G.; Barton, P. C.; Malik, A. Q.

    2013-04-01

    The formation of mild steel (MS) and copper (Cu) explosively formed projectiles (EFPs) was simulated in AUTODYN using both the Johnson-Cook (JC) and modified Johnson-Cook (JCM) constitutive models. The JC model was modified by increasing the hardening constant by 10%. The previously established semi-empirical equations for diameter, length, velocity, and depth of penetration were used to verify the design of the EFP. The length-to-diameter (L/D) ratio of the warhead used in the simulation varied between 1 < L/D < 2. To avoid projectile distortion or breakup for large standoff applications, the design of the EFP warhead was modified to obtain a lower L/D ratio. Simulations from the JC model underestimated the EFP diameter, resulting in an unrealistically elongated projectile. This shortcoming was resolved by employing the JCM model, giving good agreement with the experimental results. The projectile velocity and hole characteristics in 10-mm-thick aluminum target plates were studied for both models. The semi-empirical equations and the JC model overestimated the projectile velocity, whereas the JCM model underestimated the velocity slightly when compared to the experimental results. The depths of penetration calculated by the semi-empirical equations in the aluminum (Al) target plate were 55 and 52 mm for Cu and MS EFPs, respectively.

  1. A Technique for Obtaining Hypervelocity Impact Data by using the Relative Velocities of Two Projectiles

    NASA Technical Reports Server (NTRS)

    Kinard, William H.; Collins, Rufus D., Jr.

    1961-01-01

    A facility has been developed and put into operation to determine the feasibility of obtaining hypervelocity impact data by using the relative velocities of two projectiles. The facility utilizes the technique of firing a target toward an oncoming high-velocity projectile so that the impact velocity is equal to the sum of the projectile velocity and the target velocity. A 37-millimeter powder gun is utilized to accelerate the targets, and a specially designed 22-caliber light-gas gun accelerates the impacting projectiles. The light-gas gun is operated by detonating an explosive charge which permits it to be synchronized with the firing of the 37-millimeter gun. Impact velocities as great as 21,850 ft/sec have been obtained during development of the facility. After the oncoming projectiles impact the targets fired from the 37-millimeter gun, these targets are recovered by allowing them to impact into Celotex and soft wooden blocks. The craters formed in the targets then can be observed and measured. The results of several preliminary firings of the facility are included in this report.

  2. CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J.; Winograd, Nicholas

    2016-09-01

    The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure.

  3. Experimental investigation on underwater trajectory deviation of high-speed projectile with different nose shapes

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Huang, Wei; Gao, Yubo; Qi, Yafei; Hypervelocity Impact Research Center Team

    2015-06-01

    Laboratory-scaled oblique water entry experiments for the trajectory stability in the water column have been performed with four different nosed-projectiles at a range of velocities from 20m /s to 250 m /s . The slender projectiles are designed with flat, ogival, hemi-sperical, truncated-ogival noses to make comparisons on the trajectory deviation when they are launched at vertical and oblique impact angles (0°~25°). Two high-speed cameras that are positioned orthogonal to each other and normal to the column are employed to capture the entire process of projectiles' penetration. From the experimental results, the sequential images in two planes are presented to compare the trajectory deviation of different impact tests and the 3D trajectory models are extracted based on the location recorded by cameras. Considering the effect influenced by the impact velocities and noses of projectiles, it merited concluded that trajectory deviation is affected from most by impact angle, and least by impact velocities. Additionally, ogival projectiles tend to be more sensitive to oblique angle and experienced the largest attitude changing. National Natural Science Foundation of China (NO.: 11372088).

  4. Numerical Investigation of Bending-Body Projectile Aerodynamics for Maneuver Control

    NASA Astrophysics Data System (ADS)

    Youn, Eric; Silton, Sidra

    2015-11-01

    Precision munitions are an active area of research for the U.S. Army. Canard-control actuators have historically been the primary mechanism used to maneuver fin-stabilized, gun-launched munitions. Canards are small, fin-like control surfaces mounted at the forward section of the munition to provide the pitching moment necessary to rotate the body in the freestream flow. The additional lift force due to the rotated body and the canards then alters the flight path toward the intended target. As velocity and maneuverability requirements continue to increase, investigation of other maneuver mechanisms becomes necessary. One option for a projectile with a large length-to-diameter ratio (L/D) is a bending-body design, which imparts a curvature to the projectile body along its axis. This investigation uses full Navier-Stokes computational fluid dynamics simulations to evaluate the effectiveness of an 8-degree bent nose tip on an 8-degree bent forward section of an L/D =10 projectile. The aerodynamic control effectiveness of the bending-body concept is compared to that of a standard L/D =10 straight-body projectile as well as that of the same projectile with traditional canards. All simulations were performed at supersonic velocities between Mach 2-4.

  5. Unusual behavior of projectile fragments formed in the bombardment of copper with relativistic Ar ions

    SciTech Connect

    Dersch, G.; Beckmann, R.; Feige, G.; Lund, T.; Vater, P.; Brandt, R.; Aleklett, K.; Friedlander, E.M.; Loveland, W.; Herrmann, J.

    1984-11-01

    The interaction properties of projectile fragments from the fragmentation of 0.9 A GeV and 1.8 A GeV /sup 40/Ar with Cu have been studied using radioactivation techniques. Projectile fragments formed in the interaction of the primary Ar beam with a thick Cu disk (the target disk) interacted with a second detector Cu disk. The relative reaction product yields in the two disks were measured as a function of the separation between the disks. A large increase in the yield of deep spallation products (/sup 24/Na, /sup 28/Mg) in the detector disk was observed as the projectile energy increased from 0.9 A GeV to 1.8 A GeV. At 1.8 A GeV (but not at 0.9 A GeV) the yields of the deep spallation products decreased as the separation between the disks increased indicating either a dramatic broadening of the relevant projectile fragment angular distribution between 0.9 A GeV and 1.8 A GeV or a decay in flight of some of the projectile fragments at 1.8 A GeV (but not at 0.9 A GeV). Calculations will be discussed that cast doubt on the first possibility. 15 references.

  6. Accuracy Improvement Capability of Advanced Projectile Based on Course Correction Fuze Concept

    PubMed Central

    Elsaadany, Ahmed; Wen-jun, Yi

    2014-01-01

    Improvement in terminal accuracy is an important objective for future artillery projectiles. Generally it is often associated with range extension. Various concepts and modifications are proposed to correct the range and drift of artillery projectile like course correction fuze. The course correction fuze concepts could provide an attractive and cost-effective solution for munitions accuracy improvement. In this paper, the trajectory correction has been obtained using two kinds of course correction modules, one is devoted to range correction (drag ring brake) and the second is devoted to drift correction (canard based-correction fuze). The course correction modules have been characterized by aerodynamic computations and flight dynamic investigations in order to analyze the effects on deflection of the projectile aerodynamic parameters. The simulation results show that the impact accuracy of a conventional projectile using these course correction modules can be improved. The drag ring brake is found to be highly capable for range correction. The deploying of the drag brake in early stage of trajectory results in large range correction. The correction occasion time can be predefined depending on required correction of range. On the other hand, the canard based-correction fuze is found to have a higher effect on the projectile drift by modifying its roll rate. In addition, the canard extension induces a high-frequency incidence angle as canards reciprocate at the roll motion. PMID:25097873

  7. Accuracy improvement capability of advanced projectile based on course correction fuze concept.

    PubMed

    Elsaadany, Ahmed; Wen-jun, Yi

    2014-01-01

    Improvement in terminal accuracy is an important objective for future artillery projectiles. Generally it is often associated with range extension. Various concepts and modifications are proposed to correct the range and drift of artillery projectile like course correction fuze. The course correction fuze concepts could provide an attractive and cost-effective solution for munitions accuracy improvement. In this paper, the trajectory correction has been obtained using two kinds of course correction modules, one is devoted to range correction (drag ring brake) and the second is devoted to drift correction (canard based-correction fuze). The course correction modules have been characterized by aerodynamic computations and flight dynamic investigations in order to analyze the effects on deflection of the projectile aerodynamic parameters. The simulation results show that the impact accuracy of a conventional projectile using these course correction modules can be improved. The drag ring brake is found to be highly capable for range correction. The deploying of the drag brake in early stage of trajectory results in large range correction. The correction occasion time can be predefined depending on required correction of range. On the other hand, the canard based-correction fuze is found to have a higher effect on the projectile drift by modifying its roll rate. In addition, the canard extension induces a high-frequency incidence angle as canards reciprocate at the roll motion.

  8. Penetration Experiments with Limestone Targets and Ogive-Nose Steel Projectiles

    SciTech Connect

    Forrestal, M.J.; Frew, D.J.; Hanchak, S.J.

    1999-04-08

    We conducted three sets of depth-of-penetration experiments with limestone targets and 3.0 caliber-radius-head (CRH), ogive-nose steel rod projectiles. The limestone targets had a nominal unconfined compressive strength of 60 MPa, a density of 2.31 kg/m{sup 3}, a porosity of 15%, and a water content less than 0.4%. The ogive-nose rod projectiles with length-to-diameter ratios often were machined from 4340 R{sub c} 45 and Aer Met 100 R{sub c} 53 steel, round stock and had diameters and masses of 7.1 mm, 0.020 kg; 12.7 mm, 0.117 kg; and 25.4 mm, 0.931 kg. Powder guns or a two-stage, light-gas gun launched the projectiles at normal impacts to striking velocities between 0.4 and 1.9 km/s. For the 4340 R{sub c} 45 and Aer Met 100 R{sub c} 53 steel projectiles, penetration depth increased as striking velocity increased to a striking velocity of 1.5 and 1.7 km/s, respectively. For larger striking velocities, the projectiles deformed during penetration without nose erosion, deviated from the shot line, and exited the sides of the target. We also developed an analytical penetration equation that described the target resistance by its density and a strength parameter determined from depth of penetration versus striking velocity data.

  9. Accuracy improvement capability of advanced projectile based on course correction fuze concept.

    PubMed

    Elsaadany, Ahmed; Wen-jun, Yi

    2014-01-01

    Improvement in terminal accuracy is an important objective for future artillery projectiles. Generally it is often associated with range extension. Various concepts and modifications are proposed to correct the range and drift of artillery projectile like course correction fuze. The course correction fuze concepts could provide an attractive and cost-effective solution for munitions accuracy improvement. In this paper, the trajectory correction has been obtained using two kinds of course correction modules, one is devoted to range correction (drag ring brake) and the second is devoted to drift correction (canard based-correction fuze). The course correction modules have been characterized by aerodynamic computations and flight dynamic investigations in order to analyze the effects on deflection of the projectile aerodynamic parameters. The simulation results show that the impact accuracy of a conventional projectile using these course correction modules can be improved. The drag ring brake is found to be highly capable for range correction. The deploying of the drag brake in early stage of trajectory results in large range correction. The correction occasion time can be predefined depending on required correction of range. On the other hand, the canard based-correction fuze is found to have a higher effect on the projectile drift by modifying its roll rate. In addition, the canard extension induces a high-frequency incidence angle as canards reciprocate at the roll motion. PMID:25097873

  10. CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry.

    PubMed

    Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J; Winograd, Nicholas

    2016-09-01

    The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure. Graphical Abstract ᅟ.

  11. An experimental, metallurgical and modelling analysis of silver and copper explosively formed projectiles (EFPs)

    NASA Astrophysics Data System (ADS)

    MacMahon, J.; Church, P.; Cullis, I.; Findlay, S.; Hart, A.; Wickenden, M.

    2003-09-01

    This paper describes an experimental, metallurgical and modelling study into the structure and properties of silver and copper explosively fonned projectiles. The project started with the conditioning, processing and characterisation of the non-shocked silver and copper materials. Here, the material constants were derived for the Goldthorpe path-dependant constitutive model[1]. For the purposes of this study the warhead designs produced some conservative EFP projectiles. These were designed using the indigenous Eulerian hydrocode GRIM. Due to the ductile nature of both silver and copper, care was taken with respect to the equation of state, in particular with the temperature supplied to the constitutive models. The EFP projectiles were then experimentally recovered using soft-capturing techniques[2]. The comparison of the code predictions with the experimental radiography results was very good, suggesting that there could not be large material phase changes or significant changes to the microstructure of the material due to the explosively applied shock. Finally, the sectioning and metallurgical analysis of the recovered projectiles showed that although there were some variations in both grain size, microstructure and material hardness throughoutlacross the sectioned projectiles, these were not significant.

  12. Rate of neurodegeneration in the mouse controlled cortical impact model is influenced by impactor tip shape: implications for mechanistic and therapeutic studies.

    PubMed

    Pleasant, Jennifer M; Carlson, Shaun W; Mao, Haojie; Scheff, Stephen W; Yang, King H; Saatman, Kathryn E

    2011-11-01

    Controlled cortical impact (CCI), one of the most common models of traumatic brain injury, is being increasingly used with mice for exploration of cell injury mechanisms and pre-clinical evaluation of therapeutic strategies. Although CCI brain injury was originally effected using an impactor with a rounded tip, the majority of studies with mouse CCI use a flat or beveled tip. Recent finite element modeling analyses demonstrate that tip geometry is a significant determinant of predicted cortical tissue strains in rat CCI, and that cell death is proportional to predicted tissue strains. In the current study, a three-dimensional finite element model of a C57BL/6J mouse brain predicted higher maximum principal strains during a simulated 1.0-mm, 3.5-m/s CCI injury with a flat tip when compared to a rounded tip. Consistent with this prediction, experimental CCI with a flat-tip impactor resulted in greater acute cortical hemorrhage and neuron loss in adult male C57BL/6J mice. The amount of neocortical tissue damage was equivalent for the two tip geometries at 9 days following injury, but the rate of neocortical neurodegeneration was markedly slower following CCI with a rounded-tip impactor, with damage reaching a plateau after 24?h as opposed to after 4?h for the flat tip. The flat-tip impactor was associated in general with more regional hippocampal neurodegeneration, especially at early time points such as 4?h. Impactor tip geometry did not have a notable effect on blood?brain barrier breakdown, traumatic axonal injury, or motor and cognitive dysfunction. Execution of CCI injury with a rounded-tip impactor is posited to provide a substantially enhanced temporal window for the study of cellular injury mechanisms and therapeutic intervention while maintaining critical aspects of the pathophysiological response to contusion brain injury.

  13. Constraints on the Nature and Distribution of Iridium Host Phases at the Cretaceous-Tertiary Boundary: Implications for Projectile Identity and dispersal on impact

    NASA Technical Reports Server (NTRS)

    Schuraytz, B. C.; Lindstrom, D. J.; Sharpton, V. L.

    1997-01-01

    Among Cretaceous-Tertiary boundary sites worldwide, variations in the concentrations and ratios of elements commonly enriched in meteorites complicate traditional geochemical attempts at impactor identification. Yet they may provide constraints on the physical and chemical processes associated with large-body disruption and dispersal, as well as with diagenesis of projectile components. To this end, we continue our efforts to identify the mineral host-phases of projectile-derived elements, particularly for Ir, and to document their partitioning between crater deposits and ejecta resulting from the Chicxulub basin-forming impact. Building on earlier work, we used INAA to measure Ir concentrations in successively smaller splits of finely powdered impact melt breccia from the Chicxulub Crater in Mexico (sample Y6Nl9-R(b)), and K/T boundary fish clay from Stevns Klint, Denmark (sample FC-1, split from 40 kg of homogenized material intended as an analytical standard). Results for the Chicxulub sample show a heterogeneous Ir distribution and document that at least five discrete Ir-bearing host phases were isolated in subsequent splits, having Ir masses equivalent to pure Ir spheres from about 0.8 to about 3.5 mm in diameter. Three of these are within a sufficiently reduced mass of powder to warrant searching for them using backscattered electron microscopy. In contrast, successively smaller splits of the Stevns Klint fish clay show no statistically significant deviation from the reported value of 32 +/- 2 ng/g Ir, suggesting a uniform Ir host-phase distribution. For the smallest split obtained thus far (100 +/- 40 ng/g Ir), a pure Ir sphere of equivalent Ir mass would be <0.05 min in diameter. (n.b. Although homogenizing and sieving of FC-1 to <75 min obviously obscured variations in stratigraphic distribution, it is unlikely to have affected the size-frequency distribution of Ir host phases.) We previously identified micrometer-scale Ir host phases by electron

  14. Treatment of ion-atom collisions using a partial-wave expansion of the projectile wavefunction

    SciTech Connect

    Foster, M; Colgan, J; Wong, T G; Madison, D H

    2008-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge scattering quantities. Here we show that such calculations are possible using modern high-performance computing. We demonstrate the utility of our method by examining elastic scattering of protons by hydrogen and helium atoms, problems familiar to undergraduate students of atomic scattering. Application to ionization of helium using partial-wave expansions of the projectile wavefunction, which has long been desirable in heavy-ion collision physics, is thus quite feasible.

  15. On the non-equilibrium dynamics of cavitation around the underwater projectile in variable motion

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Lu, C. J.; Li, J.; Chen, X.; Gong, Z. X.

    2015-12-01

    In this work, the dynamic behavior of the non-equilibrium cavitation occurring around the underwater projectiles navigating with variable speed was numerically and theoretically investigated. The cavity collapse induced by the decelerating motion of the projectiles can be classified into two types: periodic oscillation and damped oscillation. In each type the evolution of the total mass of vapor in cavity are found to have strict correlation with the pressure oscillation in far field. By defining the equivalent radius of cavity, we introduce the specific kinetic energy of collapse and demonstrate that its change-rate is in good agreement with the pressure disturbance. We numerically investigated the influence of angle of attack on the collapse effect. The result shows that when the projectile decelerates, an asymmetric-focusing effect of the pressure induced by collapse occurs on its pressure side. We analytically explained such asymmetric-focusing effect.

  16. Projectile motion of a once rotating object: physical quantities at the point of return

    NASA Astrophysics Data System (ADS)

    Arabasi, Sameer

    2016-09-01

    Vertical circular motion is a widely used example to explain non-uniform circular motion in most undergraduate general physics textbooks. However, most of these textbooks do not elaborate on the case when this motion turns into projectile motion under certain conditions. In this paper, we describe thoroughly when a mass attached to a cord, moving in a vertical circular motion, turns into a projectile and its location and velocity when it rejoins the circular orbit. This paper provides an intuitive understanding, supported by basic kinematic equations, to give an interesting elegant connection between circular motion and projectile motion—something lacking in most physics textbooks—and will be very useful to present to an undergraduate class to deepen their understanding of both models of motion.

  17. Evaluating simulant materials for understanding cranial backspatter from a ballistic projectile.

    PubMed

    Das, Raj; Collins, Alistair; Verma, Anurag; Fernandez, Justin; Taylor, Michael

    2015-05-01

    In cranial wounds resulting from a gunshot, the study of backspatter patterns can provide information about the actual incidents by linking material to surrounding objects. This study investigates the physics of backspatter from a high-speed projectile impact and evaluates a range of simulant materials using impact tests. Next, we evaluate a mesh-free method called smoothed particle hydrodynamics (SPH) to model the splashing mechanism during backspatter. The study has shown that a projectile impact causes fragmentation at the impact site, while transferring momentum to fragmented particles. The particles travel along the path of least resistance, leading to partial material movement in the reverse direction of the projectile motion causing backspatter. Medium-density fiberboard is a better simulant for a human skull than polycarbonate, and lorica leather is a better simulant for a human skin than natural rubber. SPH is an effective numerical method for modeling the high-speed impact fracture and fragmentations.

  18. Evaluating simulant materials for understanding cranial backspatter from a ballistic projectile.

    PubMed

    Das, Raj; Collins, Alistair; Verma, Anurag; Fernandez, Justin; Taylor, Michael

    2015-05-01

    In cranial wounds resulting from a gunshot, the study of backspatter patterns can provide information about the actual incidents by linking material to surrounding objects. This study investigates the physics of backspatter from a high-speed projectile impact and evaluates a range of simulant materials using impact tests. Next, we evaluate a mesh-free method called smoothed particle hydrodynamics (SPH) to model the splashing mechanism during backspatter. The study has shown that a projectile impact causes fragmentation at the impact site, while transferring momentum to fragmented particles. The particles travel along the path of least resistance, leading to partial material movement in the reverse direction of the projectile motion causing backspatter. Medium-density fiberboard is a better simulant for a human skull than polycarbonate, and lorica leather is a better simulant for a human skin than natural rubber. SPH is an effective numerical method for modeling the high-speed impact fracture and fragmentations. PMID:25739515

  19. Tearing resistance of a thin shell against projectile penetration: Material property effects

    SciTech Connect

    Trinh, K.V.

    1994-01-01

    This report presents results from a series of finite element analyses performed to study material effects on the tearing resistance of a thin shell subjected to projectile penetration. These analyses simulated a round, slender projectile impacting the top center of a metallic cylindrical shell at high speed. We varied eight selected shell material properties systematically using an L18 matrix (design of experiment technique). From the results, we determined effects of the eight properties on the minimum projectile velocity required to penetrate the shell. The material properties examined here included: yield strength, hardening and recovery characteristics, heat coefficient, initial porosity, and damage exponent (a void growth parameter). The DYNA2D finite element code along with the Sandia plasticity/damage model for ductile metals were used in the analyses.

  20. Experimental investigation of magnetoplasma acceleration of dielectric projectiles in a rail gun

    SciTech Connect

    Kondratenko, M.M.; Lebedev, E.F.; Ostashev, V.E.; Safonov, V.I.; Fortov, V.E.; Ul'yanov, A.V.

    1988-07-01

    The authors present results of experimental investigations of the process of a nondestructive electrodynamic acceleration of dielectric projectiles in a magnetoplasma accelerator of rail gun type upon discharge of the electrical energy of the capacitor bank. They describe the phenomenon of decay of the plasma driving piston. They describe the causes of this phenomenon and the practical steps to avoid it. In a specific facility regimes have been achieved with electrodynamic acceleration of projectiles without plasma piston decay at working currents of up to 0.7 MA. In acceleration of projectiles of mass approx. 1 g a speed of 6 km/sec has been attained and reproduced. The facility constructed can be used efficiently in experiments to investigate the thermophysical properties of substances using dynamic methods as a means of creating intense kinetic energy pulses.

  1. KSC-05PD-0116

    NASA Technical Reports Server (NTRS)

    2005-01-01

    KENNEDY SPACE CENTER, FLA. At Ball Aerospace in Boulder, Colo., the impactor on the Deep Impact spacecraft is tested. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.

  2. Systematic study of probable projectile-target combinations for the synthesis of the superheavy nucleus 302120

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Safoora, V.

    2016-08-01

    Probable projectile-target combinations for the synthesis of the superheavy element 302120 have been studied taking the Coulomb and proximity potential as the interaction barrier. The probabilities of the compound nucleus formation PCN for the projectile-target combinations found in the cold reaction valley of 302120 are estimated. At energies near and above the Coulomb barrier, we have calculated the capture, fusion, and evaporation residue cross sections for the reactions of all probable projectile-target combinations so as to predict the most promising projectile-target combinations for the synthesis of the superheavy element 302120 in heavy-ion fusion reactions. The calculated fusion and evaporation cross sections for the more asymmetric ("hotter") projectile-target combination is found to be higher than the less asymmetric ("colder") combination. It can be seen from the nature of the quasifission barrier height, mass asymmetry, the probability of compound nucleus formation, survival probability, and excitation energy, the systems 44Ar+258No , 46Ar+256No , 48Ca+254Fm , 50Ca+252Fm , 54Ti+248Cf , and 58Cr+244Cm in deep region I of the cold reaction valley and the systems 62Fe+240Pu , 64Fe+238Pu , 68Ni+234U , 70Ni+232U , 72Ni+230U , and 74Zn+228Th in the other cold valleys are identified as the better projectile-target combinations for the synthesis of 302120. Our predictions on the synthesis of 302120 superheavy nuclei using the combinations 54Cr+248Cm , 58Fe+244Pu , 64Ni+238U , and 50Ti+249Cf are compared with available experimental data and other theoretical predictions.

  3. Computational studies of projectile melt in impact with typical whipple shields

    SciTech Connect

    Rhoades, C.E. Jr.; Alme, M.L.

    1994-12-01

    Protecting space-based structures against the impact of orbital debris is an important problem of current interest. This paper presents scaling results based on simulations with the CALE computer program of aluminum projectile impacting typical aluminum Whipple shields at speeds of 6 to 14 km/s. The objective was to determine the extent of projectile and shield material melting. The approach was to perform a matrix of computer simulations varying the impact speed from 6 to 14 km/s and varying the areal density of the shield from 5 percent to 80 percent of the centerline areal density of the projectile. The projectile radius was fixed at 9.5 mm (mass = 1.27 grams). The melt state of the projectile material and the shield material was assessed after release of the initial shock. The post-release specific energy in the projectile and in the shield was compared with the enthalpy of incipient melt and the enthalpy of complete melt provided in the Hultgren Tables. Material with specific energy greater than the enthalpy of complete melt was assumed to be fully melted. Material with specific energy greater than the enthalpy of incipient melt but less than that of complete melt was assumed to be partially solid and partially melted mixed phase material with no strength. Material with specific energy less than the enthalpy of incipient melt was assumed to be in a solid state with strength. It is likely that this solid material is in a highly fragmented state as a result of the initial shock.

  4. Refrigeration and freezing of porcine tissue does not affect the retardation of fragment simulating projectiles.

    PubMed

    Breeze, J; Carr, D J; Mabbott, A; Beckett, S; Clasper, J C

    2015-05-01

    Explosively propelled fragments are the most common cause of injury to UK service personnel in modern conflicts. Numerical injury models to simulate such injuries utilise algorithms based upon gelatin and animal tissue testing but data is limited on many fragment simulating projectiles and these simulants cannot represent human anatomy. Testing with post mortem specimens may overcome this limitation but no information exists about how post mortem tissue changes and storage conditions in humans or animals may affect projectile penetration. Two chisel nosed cylinders (0.49 g and 1.10 g) and a 0.51 g (5 mm) sphere were fired into three groups of porcine tissue (fresh, refrigerated and frozen then refrigerated) and compared to 20% gelatin. Depth of projectile penetration was ascertained with the assistance of computed tomography and kinetic energy absorption by tissues measured using Doppler radar and high speed photography. No difference in depth of penetration was found between porcine tissue stored in the different manners compared with 20% gelatin by impact velocities less than 100 m/s. Insufficient numbers of projectiles were retained in tissue at higher velocities for statistical analysis to be undertaken. Energy absorbed per millimetre of tissue ranged between 0.42 and 0.98 J/mm for different porcine tissue despite differing storage. This pilot study would suggest that the effect of refrigerating or freezing porcine tissue followed by thawing has no effect on its ability to retard these projectiles. Further research is required to ascertain if these results occur at greater velocities and for other types of projectile. PMID:25882156

  5. Study on measurement method for projectile location based on light screen

    NASA Astrophysics Data System (ADS)

    Han, Feng; Liu, QunHua; Sun, GuoBin

    2008-09-01

    In weapon-ammunition system, firing accuracy of projectile is major characteristic parameter weighing fire effect and capability of weapon-ammunition system for target. At present, firing accuracy of projectile is obtained by measuring the two-dimensional coordinates of projectile for target. In order to measure the parameters of two-dimensional coordinates of projectile for target, a new type of measurement system is proposed. The measurement system is composed of four high sensitivity light screens (known as target) with special geometrical frame. Light source of the screens is formed by special infrared LED array. The PIN infrared photodiodes array is used as the sensors. The longest effective distance between light source and sensors is 4m. It is impossible to achieve using traditional methods. Four light screens and high-precision timers are combined in order to acquire the value of time when the projectile flies across the position of four light screens. The real-time data acquirement and processing and display of two-dimensional coordinates and the projectile velocity can be realized. The principle of measurement system and the design of high sensitivity light screen are introduced emphatically. The measurement system was verified by using five kinds of small caliber pellets. As compared with the paper target sheet, the measurement system designed can meet the demand of check-up test of gun, bullet and ammunition. The firing testing in the target field has proved that the measurement system has the advantages of simple construction, easy operation and high precision and high sensitivity.

  6. Refrigeration and freezing of porcine tissue does not affect the retardation of fragment simulating projectiles.

    PubMed

    Breeze, J; Carr, D J; Mabbott, A; Beckett, S; Clasper, J C

    2015-05-01

    Explosively propelled fragments are the most common cause of injury to UK service personnel in modern conflicts. Numerical injury models to simulate such injuries utilise algorithms based upon gelatin and animal tissue testing but data is limited on many fragment simulating projectiles and these simulants cannot represent human anatomy. Testing with post mortem specimens may overcome this limitation but no information exists about how post mortem tissue changes and storage conditions in humans or animals may affect projectile penetration. Two chisel nosed cylinders (0.49 g and 1.10 g) and a 0.51 g (5 mm) sphere were fired into three groups of porcine tissue (fresh, refrigerated and frozen then refrigerated) and compared to 20% gelatin. Depth of projectile penetration was ascertained with the assistance of computed tomography and kinetic energy absorption by tissues measured using Doppler radar and high speed photography. No difference in depth of penetration was found between porcine tissue stored in the different manners compared with 20% gelatin by impact velocities less than 100 m/s. Insufficient numbers of projectiles were retained in tissue at higher velocities for statistical analysis to be undertaken. Energy absorbed per millimetre of tissue ranged between 0.42 and 0.98 J/mm for different porcine tissue despite differing storage. This pilot study would suggest that the effect of refrigerating or freezing porcine tissue followed by thawing has no effect on its ability to retard these projectiles. Further research is required to ascertain if these results occur at greater velocities and for other types of projectile.

  7. Maximum projectile range with drag and lift, with particular application to golf

    NASA Astrophysics Data System (ADS)

    Erlichson, Herman

    1983-04-01

    This paper explores the interesting problem of projectile motion without the vacuum idealization. Particular attention is paid to golf ball trajectories with and without lift. No lift trajectories with linear and quadratic drag are considered first. Then, trajectories with lift and linear drag are investigated. Projection angles for maximum range are determined for all these cases. Computer solutions are used throughout, with a Runge-Kutta routine used for all cases except for the well-known closed solution for the no lift, linear drag projectile.

  8. Non-lead, environmentally safe projectiles and method of making same

    DOEpatents

    Lowden, R.A.; McCoig, T.M.; Dooley, J.B.

    1998-06-02

    A projectile, such as a bullet, is made by combining two different metals in proportions calculated to achieve a desired density, without using lead. A base constituent, made of a material having density greater than lead, is combined with a binder constituent having less density. The binder constituent is malleable and ductile metallic phase material that forms projectile shapes when subjected to a consolidation force, such as compression. The metal constituents can be selected, rationed, and consolidated to achieve desired frangibility characteristics. 7 figs.

  9. [A sign of the rotational impact of the gunshot projectile on the flat bone].

    PubMed

    Leonov, S V

    2014-01-01

    The objective of the present work was to study the mechanisms of formation of the gunshot fracture of the flat bones with special reference to the translational and rotational motion of the projectile. A total of 120 real and experimental injuries of this type were available for the investigation with the use of simulation by the finite-elemental analysis. A set of morphological features has been identified that make it possible to determine the direction of rotation of the gunshot projectile. PMID:25764858

  10. Micrometeoroid Impacts on the Hubble Sace Telescope Wide Field and Planetary Camera 2: Ion Beam Analysis of Subtle Impactor Traces

    NASA Technical Reports Server (NTRS)

    Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.; Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.; Griffin, T.; Gerlach, L.; Wozniakiewicz, P. J.; Price, M. C.; Burchell, M. J.; Cole, M. J.

    2014-01-01

    Recognition of origin for particles responsible for impact damage on spacecraft such as the Hubble Space Telescope (HST) relies upon postflight analysis of returned materials. A unique opportunity arose in 2009 with collection of the Wide Field and Planetary Camera 2 (WFPC2) from HST by shuttle mission STS-125. A preliminary optical survey confirmed that there were hundreds of impact features on the radiator surface. Following extensive discussion between NASA, ESA, NHM and IBC, a collaborative research program was initiated, employing scanning electron microscopy (SEM) and ion beam analysis (IBA) to determine the nature of the impacting grains. Even though some WFPC2 impact features are large, and easily seen without the use of a microscope, impactor remnants may be hard to find.

  11. Research on Impact Stress and Fatigue Simulation of a New Down-to-the-Hole Impactor Based on ANSYS

    NASA Astrophysics Data System (ADS)

    Wu, Tao; Wang, Wei; Yao, Aiguo; Li, Yongbo; He, Wangyong; Fei, Dongdong

    2016-06-01

    In the present work, a down-to-the-hole electric hammer driven by linear motor is reported for drilling engineering. It differs from the common hydraulic or pneumatic hammers in that it can be applied to some special occasions without circulating medium due to its independence of the drilling fluid. The impact stress caused by the reciprocating motion between stator and rotor and the fatigue damage in key components of linear motor are analyzed by the ANSYS Workbench software and 3D model. Based on simulation results, the hammer's structure is optimized by using special sliding bearing, increasing the wall thickness of key and multilayer buffer gasket. Fatigue life and coefficient issues of the new structure are dramatically improved. However buffer gasket reduces the impactor's energy, different bumper structure effect on life improving and energy loss have also been elaborated.

  12. Physics Learning Achievement Study: Projectile, Using Mathematica Program of Faculty of Science and Technology Phetchabun Rajabhat University Students

    ERIC Educational Resources Information Center

    Hutem, Artit; Kerdmee, Supoj

    2013-01-01

    The propose of this study is to study Physics Learning Achievement, projectile motion, using the Mathematica program of Faculty of Science and Technology Phetchabun Rajabhat University students, comparing with Faculty of Science and Technology Phetchabun Rajabhat University students who study the projectile motion experiment set. The samples are…

  13. Particle Size Distributions of Particulate Emissions from the Ferroalloy Industry Evaluated by Electrical Low Pressure Impactor (ELPI)

    PubMed Central

    Kero, Ida; Naess, Mari K.; Tranell, Gabriella

    2015-01-01

    The present article presents a comprehensive evaluation of the potential use of an Electrical Low Pressure Impactor (ELPI) in the ferroalloy industry with respect to indoor air quality and fugitive emission control. The ELPI was used to assess particulate emission properties, particularly of the fine particles (Dp ≤ 1 μm), which in turn may enable more satisfactory risk assessments for the indoor working conditions in the ferroalloy industry. An ELPI has been applied to characterize the fume in two different ferroalloy plants, one producing silicomanganese (SiMn) alloys and one producing ferrosilicon (FeSi) alloys. The impactor classifies the particles according to their aerodynamic diameter and gives real-time particle size distributions (PSD). The PSD based on both number and mass concentrations are shown and compared. Collected particles have also been analyzed by transmission and scanning electron microscopy with energy dispersive spectroscopy. From the ELPI classification, particle size distributions in the range 7 nm – 10 μm have been established for industrial SiMn and FeSi fumes. Due to the extremely low masses of the ultrafine particles, the number and mass concentration PSD are significantly different. The average aerodynamic diameters for the FeSi and the SiMn fume particles were 0.17 and 0.10 μm, respectively. Based on this work, the ELPI is identified as a valuable tool for the evaluation of airborne particulate matter in the indoor air of metallurgical production sites. The method is well suited for real-time assessment of morphology (particle shape), particle size, and particle size distribution of aerosols. PMID:25380385

  14. The comparison of fluid dynamics parameters in an Andersen cascade impactor equipped with and without a preseparator.

    PubMed

    Dechraksa, Janwit; Suwandecha, Tan; Maliwan, Kittinan; Srichana, Teerapol

    2014-06-01

    The fluid dynamic data in Andersen cascade impactor (ACI) are still lacking. Airflows and those affected parameters can be predicted in a preseparator and Andersen cascade impactor (ACI) by computational modeling. This study developed a validated computational fluid dynamic (CFD) model of an ACI and investigated the effects of the preseparator on the CFD parameters. Validation of the computational nozzle velocity for each of the stage 0 to stage 5 of the ACI stages was found to be within a 3.56% error. The flow field indicated that the preseparator accelerated the airflow velocity at the induction tube from 1.13 to 3.71 ± 0.09 m/s and 2.40 to 8.68 ± 0.16 m/s (at 28.3 and 60 L/min of flow rate, respectively). The preseparator produced a nozzle's wall shear stress ranged from 0.08 to 0.34 Pa on a collection plate, while the ex-preseparator spread wall shear from the plate's center was in a range of 0.11 to 0.37 Pa (at 28.3 L/min of flow rate). Moreover, the nozzle velocities increased along the distance from the middle of the collection plate to the periphery. The CFD explained the airflow of the preseparator equipped model by accelerating the airflow along the inlet port to maximize the trapping of desirable particles and the generation of a smooth wall shear stress at the collection plate to reduce the particle re-entrainment. While, the ex-preseparator generated an airflow that resulted in a higher wall shear stress occurring on the lower stages.

  15. The african origin of complex projectile technology: an analysis using tip cross-sectional area and perimeter.

    PubMed

    Sisk, Matthew L; Shea, John J

    2011-01-01

    Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as effective projectile armatures. Here we use this in combination with an alternate measure, the Tip Cross-Sectional Perimeter, a more accurate proxy of the force needed to penetrate a target to a lethal depth. The current study discusses this measure and uses it to analyze a collection of measurements from African Middle Stone Age pointed stone artifacts. Several point types that were rejected in previous studies are statistically indistinguishable from ethnographic projectile points using this new measure. The ramifications of this finding for a Middle Stone Age origin of complex projectile technology is discussed.

  16. The African Origin of Complex Projectile Technology: An Analysis Using Tip Cross-Sectional Area and Perimeter

    PubMed Central

    Sisk, Matthew L.; Shea, John J.

    2011-01-01

    Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as effective projectile armatures. Here we use this in combination with an alternate measure, the Tip Cross-Sectional Perimeter, a more accurate proxy of the force needed to penetrate a target to a lethal depth. The current study discusses this measure and uses it to analyze a collection of measurements from African Middle Stone Age pointed stone artifacts. Several point types that were rejected in previous studies are statistically indistinguishable from ethnographic projectile points using this new measure. The ramifications of this finding for a Middle Stone Age origin of complex projectile technology is discussed. PMID:21755048

  17. Projectile Motion with a Drag Force: Were the Medievals Right After All?

    ERIC Educational Resources Information Center

    La Rocca, Paola; Riggi, Francesco

    2009-01-01

    An educational and historical study of the projectile motion with drag forces dependent on speed shows, by simple results, that trajectories quite similar to those depicted before the Galilean era may be obtained with a realistic choice of quantities involved. Numerical simulations of the trajectory in space and velocity coordinates help us to…

  18. Evaluation of eye injury risk from projectile shooting toys using the focus headform - biomed 2009.

    PubMed

    Bisplinghoff, Jill A; Duma, Stefan M

    2009-01-01

    Half of eye injuries in the United States are caused by a blunt impact and more specifically, eye injuries effecting children often result from projectile shooting toys. The purpose of this study is to evaluate the risk of eye injuries of currently available projectile shooting toys. In order to assess the risk of each toy, a Facial and Ocular Countermeasure Safety (FOCUS) headform was used to measure the force applied to the eye during each hit for a total of 18 tests. The selected toys included a dart gun, a foam launcher, and a ball launcher. The force ranged from 4-93 N and was analyzed using the injury risk function for globe rupture for the FOCUS headform. Projectile characteristics were also examined using normalized energy to determine risk of corneal abrasion, hyphema, lens dislocation, retinal damage and globe rupture. It was found that the three toys tested produced peak loads corresponding with risk of globe rupture between 0% and 17.3%. The normalized energy results show no risk of hyphema, lens dislocation, retinal damage or globe rupture and a maximum risk of corneal abrasion of 5.9%. This study concludes that although there are many eye injuries caused by projectiles, the selected toys show a very low risk of eye injury.

  19. Projectile image acceleration, neutralization and electron emission during grazing interactions of multicharged ions with Au(110)

    SciTech Connect

    Meyer, F.W.; Folkerts, L.; Folkerts, H.O.; Schippers, S. |

    1995-03-01

    Recent Oak Ridge work is summarized on projectile energy gain by image charge acceleration, scattered ion charge distributions, and K-Auger electron emission during low energy grazing interactions of highly charged Pb, I, O, and Ar ions with a Au(110) surface.

  20. On projectile fragmentation at high-velocity perforation of a thin bumper

    NASA Astrophysics Data System (ADS)

    Myagkov, N. N.; Stepanov, V. V.

    2014-09-01

    By means of 3D numerical simulations, we study the statistical properties of the fragments cloud formed during high-velocity impact of a spherical projectile on a mesh bumper. We present a quantitative description of the projectile fragmentation, and study the nature of the transition from the damage to the fragmentation of the projectile when the impact velocity varies. A distinctive feature of the present work is that the calculations are carried out by smoothed particle hydrodynamics (SPH) method applied to the equations of mechanics of deformable solids (MDS). We describe the materials behavior by the Mie-Grüneisen equation of state and the Johnson-Cook model for the yield strength. The maximum principal stress spall model is used as the fracture model. It is shown that the simulation results of fragmentation based on the MDS equations by the SPH method are qualitatively consistent with the results obtained earlier on the basis of the molecular dynamics and discrete element models. It is found that the power-law distribution exponent does not depend on energy imparted to the projectile during the high-velocity impact. At the same time, our calculations show that the critical impact velocity, the power-law exponent and other critical exponents depend on the fracture criterion.

  1. Approximate Formula for the Vertical Asymptote of Projectile Motion in Midair

    ERIC Educational Resources Information Center

    Chudinov, Peter Sergey

    2010-01-01

    The classic problem of the motion of a point mass (projectile) thrown at an angle to the horizon is reviewed. The air drag force is taken into account with the drag factor assumed to be constant. An analytical approach is used for the investigation. An approximate formula is obtained for one of the characteristics of the motion--the vertical…

  2. Effect of initial projectile speed on contamination distribution in a lower extremity surrogate "wound track".

    PubMed

    Krebsbach, Meaghen A; Muci-Küchler, Karim Heinz; Hinz, Brandon J

    2012-05-01

    This article presents an experimental study that examines the relationship between initial projectile speed and bacterial distribution along a wound track due to surface contamination. A ballistic gelatin cylinder was used as a lower extremity surrogate, and surface contamination was simulated using circular filter paper moistened with a solution containing Escherichia coli strain K-12 that was previously transformed to express green fluorescent protein and be resistant to ampicillin. An 11.43-mm caliber round-nose lead projectile was shot through the contaminated area and into the extremity surrogate at firing velocities ranging from 61 to 199 m/s. The "wound track" was extracted and cut into 10 evenly spaced slices. Then, the permanent cavity was removed from each slice using a biopsy punch, liquefied, and grown on selective agar containing ampicillin. Direct and normalized bacterial colony counts and normalized extents of area covered by bacteria colonies were used to compare the differences between distribution trends corresponding to different projectile speeds. The results obtained showed that, for the cases considered, an increase in projectile speed resulted in a significant shift in the percentage of contamination from the "wound" entrance region to the "wound" exit region. PMID:22645885

  3. The Effect of Cooperative Learning on Grade 12 Learners' Performance in Projectile Motions, South Africa

    ERIC Educational Resources Information Center

    Kibirige, Israel; Lehong, Moyahabo Jeridah

    2016-01-01

    The study explored the effect of cooperative learning on Grade 12 learners' performance in projectile motions. A quasi-experimental research design with non-equivalent control group was used. Two schools were purposively selected from Maleboho Central circuit in South Africa based on their performance in Physical Sciences Grade 12 results of 2011.…

  4. [Human bone fragment acting as a secondary projectile set off by an explosion].

    PubMed

    Rezende-Neto, João Baptista de; Carneiro, Júnia Lira; Sampaio, Felipe Dias; Rodrigues, João Batista; Drumond, Domingos André F

    2012-01-01

    We report a case of a secondary projectile emanated from a fractured human bone from a victim of a bomb explosion. We also refer to the potential of transmition of blood-borne or body fluid pathogens by this mechanism of injury.

  5. Development of a numerical model for the ballistic penetration of Fackler gelatine by small calibre projectiles

    NASA Astrophysics Data System (ADS)

    Gilson, L.; Rabet, L.; Imad, A.; Kakogiannis, D.; Coghe, F.

    2016-05-01

    Among the different material surrogates used to study the effect of small calibre projectiles on the human body, ballistic gelatine is one of the most commonly used because of its specific material properties. For many applications, numerical simulations of this material could give an important added value to understand the different phenomena observed during ballistic testing. However, the material response of gelatine is highly non-linear and complex. Recent developments in this field are available in the literature. Experimental and numerical data on the impact of rigid steel spheres in gelatine available in the literature were considered as a basis for the selection of the best model for further work. For this a comparison of two models for Fackler gelatine has been made. The selected model is afterwards exploited for a real threat consisting of two types of ammunitions: 9 mm and .44 Magnum calibre projectiles. A high-speed camera and a pressure sensor were used in order to measure the velocity decay of the projectiles and the pressure at a given location in the gelatine during penetration of the projectile. The observed instability of the 9 mm bullets was also studied. Four numerical models were developed and solved with LS-DYNA and compared with the experimental data. Good agreement was obtained between the models and the experiments validating the selected gelatine model for future use.

  6. Jamming effectiveness analysis of IR smoke projectile based on sight optical observation

    NASA Astrophysics Data System (ADS)

    Wang, Longtao; Liu, Zhenxing; Wang, Falong

    2013-09-01

    This text makes use of the similar of the principle between IR imaging guided missile detection system and the general sight optics probe. In this text, the synopsis analysis on the jamming effectiveness of the IR smoke projectile resist the IR imaging guided missile is discussed. This research of the jamming technique to IR imaging guided missile have a very realistic meaning.

  7. Analytical evaluation of the trajectories of hypersonic projectiles launched into space

    NASA Astrophysics Data System (ADS)

    Stutz, John David

    An equation of motion has been derived that may be solved using simple analytic functions which describes the motion of a projectile launched from the surface of the Earth into space accounting for both Newtonian gravity and aerodynamic drag. The equation of motion is based upon the Kepler equation of motion differential and variable transformations with the inclusion of a decaying angular momentum driving function and appropriate simplifying assumptions. The new equation of motion is first compared to various numerical and analytical trajectory approximations in a non-rotating Earth reference frame. The Modified Kepler solution is then corrected to include Earth rotation and compared to a rotating Earth simulation. Finally, the modified equation of motion is used to predict the apogee and trajectory of projectiles launched into space by the High Altitude Research Project from 1961 to 1967. The new equation of motion allows for the rapid equalization of projectile trajectories and intercept solutions that may be used to calculate firing solutions to enable ground launched projectiles to intercept or rendezvous with targets in low Earth orbit such as ballistic missiles.

  8. On the Locus Formed by the Maximum Heights of Projectile Motion with Air Resistance

    ERIC Educational Resources Information Center

    Hernandez-Saldana, H.

    2010-01-01

    We present an analysis on the locus formed by the set of maxima of the trajectories of a projectile launched in a medium with linear drag. Such a place, the locus of apexes, is written in terms of the Lambert "W" function in polar coordinates, confirming the special role played by this function in the problem. To characterize the locus, a study of…

  9. A heavy ion spectrometer system for the measurement of projectile fragmentation of relativistic heavy ions

    SciTech Connect

    Engelage, J.; Crawford, H.J.; Greiner, L.; Kuo, C.

    1996-06-01

    The Heavy Ion Spectrometer System (HISS) at the LBL Bevalac provided a unique facility for measuring projectile fragmentation cross sections important in deconvolving the Galactic Cosmic Ray (GCR) source composition. The general characteristics of the apparatus specific to this application are described and the main features of the event reconstruction and analysis used in the TRANSPORT experiment are discussed.

  10. The scaling and dynamics of a projectile obliquely impacting a granular medium.

    PubMed

    Wang, Dengming; Ye, Xiaoyan; Zheng, Xiaojing

    2012-01-01

    In this paper, the dynamics of a spherical projectile obliquely impacting into a two-dimensional granular bed is numerically investigated using the discrete element method. The influences of projectile's initial velocities and impacting angles are mainly considered. Numerical results show that the relationship between the final penetration depth and the initial impact velocity is very similar to that in the vertical-impact case. However, the dependence of the stopping time on the impact velocity of the projectile exhibits critical characteristics at different impact angles: the stopping time approximately increases linearly with the impact velocity for small impact angles but decreases in an exponential form for larger impact angles, which demonstrates the existence of two different regimes at low and high impact angles. When the impact angle is regarded as a parametric variable, a phenomenological force model at large impact angles is eventually proposed based on the simulation results, which can accurately describe the nature of the resistance force exerted on the projectile by the granular medium at different impact angels during the whole oblique-impact process. The degenerate model agrees well with the existing experimental results in the vertical-impact cases.

  11. Interaction of 3d transition metal atoms with charged ion projectiles from Electron Nuclear Dynamics computation

    NASA Astrophysics Data System (ADS)

    Hagelberg, Frank

    2003-03-01

    Computational results on atomic scattering between charged projectiles and transition metal target atoms are presented. This work aims at obtaining detailed information about charge, spin and energy transfer processes that occur between the interacting particles. An in-depth understanding of these phenomena is expected to provide a theoretical basis for the interpretation of various types of ion beam experiments, ranging from gas phase chromatography to spectroscopic observations of fast ions in ferromagnetic media. This contribution focuses on the scattering of light projectiles ranging from He to O, that are prepared in various initial charge states, by 3d transition metal atoms. The presented computations are performed in the framework of Electron Nuclear Dynamics (END)^1 theory which incorporates the coupling between electronic and nuclear degrees of freedom without reliance on the computationally cumbersome and frequently intractable determination of potential energy surfaces. In the present application of END theory to ion - transition metal atom scattering, a supermolecule approach is utilized in conjunction with a spin-unrestricted single determinantal wave function describing the electronic system. Integral scattering, charge and spin exchange cross sections are discussed as functions of the elementary parameters of the problem, such as projectile and target atomic numbers as well as projectile charge and initial kinetic energy. ^1 E.Deumens, A.Diz, R.Longo, Y.Oehrn, Rev.Mod.Phys. 66, 917 (1994)

  12. Amazing Physics: Learning about Work, Energy and Projectile Motion in a Historical Context

    ERIC Educational Resources Information Center

    Tural, Guner

    2013-01-01

    Teaching physics through a historical context provides effective learning and increases students' motivation for and interest in physics. For example, trebuchets and mangonels may be interesting historical contexts for learning about energy, work, and projectile motion. In this study, the implementation of physics lessons related to these…

  13. Eulerian simulation of the perforation of aluminum plates by nondeforming projectiles

    SciTech Connect

    Silling, S.A.

    1992-03-01

    A new algorithm for the treatment of sliding interfaces between solids with or without friction in an Eulerian wavecode is described. The algorithm has been implemented in the two-dimensional version of the CTH code. The code was used to simulate penetration and perforation of aluminum plates by rigid, conical-nosed tungsten projectiles. Comparison with experimental data is provided.

  14. A numerical study of nonstationary plasma and projectile motion in a rail gun

    NASA Astrophysics Data System (ADS)

    Zvezdin, A. M.; Kovalev, V. L.

    1992-10-01

    Changes in plasma parameters and projectile velocity and acceleration in a rail gun during the launch are investigated numerically. The method involves determining the velocity and magnetic induction using a difference scheme and an explicit nonlinear method with flow correction for calculating plasma density. The accuracy of the method proposed here is demonstrated by comparing the results with data in the literature.

  15. Measurement of projectile trajectory in dielectric target with micropower-impluse radar

    SciTech Connect

    Baum, D.W.; Kuklo, R.M.; Rosenbury, E.T.; Simonson, S.C.

    1997-11-20

    The micropower-impulse radar has been adapted for non-intrusive tracking of projectiles in dielectric targets. The main application of this technique is intended to be the validation of continuum mechanics simulation codes and material models used in the study of the interaction between high-velocity penetrators and concrete targets. Two experiments have been conducted in which a gun-launched 90-mm-diameter projectile was fired at velocities of 160 and 230 m/s into a cubical box filled with dry sand and tracked with the micropower-impulse radar. The system was adjusted so that a 2-m range in sand was divided into 511 timing intervals, which were swept every 0.1 ms. As the projectile took approximately 40 ms to come to rest this meant that there were 400measurements of its position. The CALE continuum mechanics simulation was used to model the projectile motion in the target, and close agreement was found with the measured trajectory.

  16. Resistance and rupture analysis of single- and few-layer graphene nanosheets impacted by various projectiles

    NASA Astrophysics Data System (ADS)

    Sadeghzadeh, Sadegh; Liu, Ling

    2016-09-01

    In this paper, a quasi-classical model for the collision of various nanoparticles with single- and few-layer graphene nanosheets was introduced as a multi-scale approach that couples non-equilibrium molecular dynamics with the Finite Element Method. As a resistance criterion, it was observed that the coefficient of restitution and the induced stresses depend on the impact velocity of projectile. These parameters were evaluated computationally, and it was revealed that certain resulting behaviors differ from behaviors at the macro scale. By obtaining an out-of-plane yield stress limit of 1.0 TPa for graphene, the stress analysis of single- and multi-layer graphene sheets revealed that the limit projectile velocity needed for the yielding of graphene sheets increases with the increase in the number of layers. For aluminum nanoparticles, this increase is almost linear, and for other metals, it slightly deviates from the linear trend. It was also observed that the graphene sheets have a different rupture form when impacted by gaseous molecules than by metal particles. Considering the very high momentum of gas molecules and their shock-like behavior during high-speed collisions with a graphene sheet, pores with a size of one carbon atom can be created in graphene sheets. Since a single-layer graphene sheet can withstand a projectile which is 3.64 times larger than a projectile impacting a 20-layer graphene sheet, spaced graphene sheets seem to be more effective in absorbing the impact energy of projectiles than conventional few-layer graphene sheets.

  17. Experimental study of the expansion dynamic of 9 mm Parabellum hollow point projectiles in ballistic gelatin.

    PubMed

    Bresson, F; Ducouret, J; Peyré, J; Maréchal, C; Delille, R; Colard, T; Demondion, X

    2012-06-10

    We study in this paper the expanding behaviour of hollow point 9 mm Parabellum projectiles (Hornady XTP(®) and Speer Gold Dot(®)). We defined a deformation rate that takes into account both the diameter increase and the length reduction. We plotted the behaviour of this parameter versus impact velocity (we refer to this curve as the expanding law). This expanding law has been plotted for different gelatin weight ratios and different gelatin block lengths. We completed our experiments with a set of high speed movies in order to correlate the deceleration to the state of expansion and size of the temporary cavity. Our results pointed out that full expansion is reached shortly after the projectile fully penetrates the gelatin. This result shows that the key point to accurately simulate human body interaction with a hollow point projectile is to accurately simulate the interface (skin, skull, clothes thoracic walls). Simulating accurately organs is only an issue if a quantitative comparison between penetration depths is required, but not if we only focus on the state of expansion of the projectile. By varying the gelatin parameters, we discovered that the expanding law exhibits a velocity threshold below which no expansion occurs, followed by a rather linear curve. The parameters of that expanding law (velocity threshold and line slope) vary with the gelatin parameters, but our quantitative results demonstrate that these parameters are not extremely critical. Finally, our experiments demonstrate that the knowledge of the expansion law can be a useful tool to investigate a gunshot in a human body with a semi-jacketed projectile, giving an estimation of the impact velocity and thus the shooting distance. PMID:22269130

  18. Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part I: Engineering model for the mass loss and nose-blunting of ogive-nosed projectiles

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Chen, Xiao-Wei; He, Li-Lin; Fang, Qin

    2014-12-01

    The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator, obviously reducing the penetration efficiency of penetrator. Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface, an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile. A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile. The critical value V {0/c} of the initial striking velocity is formulated, and the mass loss of projectile tends to increase weakly nonlinearly with I/ N when V 0 < V {0/c}, whilst the mass loss is proportional to the initial kinetic energy of projectile when V 0 < V {0/c}. The theoretical prediction of V {0/c} is further confirmed to be very close to the experimental value of 1.0 km/s based on 11 sets of different penetration tests. Also the validity of the proposed expressions of mass loss and nose-blunting coefficients of a projectile are verified by the tests. Therefore, a theoretical basis is for the empirical conclusions drawn in previous publications. Regarding the completely empirical determinations of the mass loss and nose-blunting coefficients given in previous papers, the present analysis reveals its physical characteristic and also guarantees its prediction accuracy. The engineering model established in the present paper forms the basis for further discussions on the structural stability and the terminal ballistic stability of ogive-nosed projectiles high-speed penetrating into concrete targets, which will respectively be elaborated in Part II and Part III of the present study.

  19. A High-Spin Rate Measurement Method for Projectiles Using a Magnetoresistive Sensor Based on Time-Frequency Domain Analysis

    PubMed Central

    Shang, Jianyu; Deng, Zhihong; Fu, Mengyin; Wang, Shunting

    2016-01-01

    Traditional artillery guidance can significantly improve the attack accuracy and overall combat efficiency of projectiles, which makes it more adaptable to the information warfare of the future. Obviously, the accurate measurement of artillery spin rate, which has long been regarded as a daunting task, is the basis of precise guidance and control. Magnetoresistive (MR) sensors can be applied to spin rate measurement, especially in the high-spin and high-g projectile launch environment. In this paper, based on the theory of a MR sensor measuring spin rate, the mathematical relationship model between the frequency of MR sensor output and projectile spin rate was established through a fundamental derivation. By analyzing the characteristics of MR sensor output whose frequency varies with time, this paper proposed the Chirp z-Transform (CZT) time-frequency (TF) domain analysis method based on the rolling window of a Blackman window function (BCZT) which can accurately extract the projectile spin rate. To put it into practice, BCZT was applied to measure the spin rate of 155 mm artillery projectile. After extracting the spin rate, the impact that launch rotational angular velocity and aspect angle have on the extraction accuracy of the spin rate was analyzed. Simulation results show that the BCZT TF domain analysis method can effectively and accurately measure the projectile spin rate, especially in a high-spin and high-g projectile launch environment. PMID:27322266

  20. A High-Spin Rate Measurement Method for Projectiles Using a Magnetoresistive Sensor Based on Time-Frequency Domain Analysis.

    PubMed

    Shang, Jianyu; Deng, Zhihong; Fu, Mengyin; Wang, Shunting

    2016-01-01

    Traditional artillery guidance can significantly improve the attack accuracy and overall combat efficiency of projectiles, which makes it more adaptable to the information warfare of the future. Obviously, the accurate measurement of artillery spin rate, which has long been regarded as a daunting task, is the basis of precise guidance and control. Magnetoresistive (MR) sensors can be applied to spin rate measurement, especially in the high-spin and high-g projectile launch environment. In this paper, based on the theory of a MR sensor measuring spin rate, the mathematical relationship model between the frequency of MR sensor output and projectile spin rate was established through a fundamental derivation. By analyzing the characteristics of MR sensor output whose frequency varies with time, this paper proposed the Chirp z-Transform (CZT) time-frequency (TF) domain analysis method based on the rolling window of a Blackman window function (BCZT) which can accurately extract the projectile spin rate. To put it into practice, BCZT was applied to measure the spin rate of 155 mm artillery projectile. After extracting the spin rate, the impact that launch rotational angular velocity and aspect angle have on the extraction accuracy of the spin rate was analyzed. Simulation results show that the BCZT TF domain analysis method can effectively and accurately measure the projectile spin rate, especially in a high-spin and high-g projectile launch environment. PMID:27322266

  1. An Integrated High Speed Photography And Flash X-Ray Instrumentation System For The Evaluation Of Projectile Behaviour In Soft Media

    NASA Astrophysics Data System (ADS)

    Macintyre, I. B.; Opalko, J. A.

    1985-02-01

    In studying the behaviour of different projectiles when penetrating a target, in this case gelatin, the development of an integrated flash X-ray, high speed photography and ballistic screen instrumentation system has proven useful for gaining qualitative and quantitative data of the projectile motion before, during and after penetration. The system discussed permits a three dimensional analysis of projectile behaviour inside the target, thereby providing measurements of projectile velocity, yaw and tumble, and enabling the study of the cavity formed by the projectile at various instants during penetration. Methodologies are compared and the uncertainties of the measurement techniques are discussed.

  2. Physical and Chemical Characterization of Particles in the Upper Troposphere and Lower Stratosphere: Microanalysis of Aerosol Impactor Samples

    NASA Technical Reports Server (NTRS)

    Sheridan, Patrick J.

    1999-01-01

    Herein is reported activities to support the characterization of the aerosol in the upper troposphere (UT) and lower stratosphere (LS) collected during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) missions in 1994. Through a companion proposal, another group was to measure the size distribution of aerosols in the 0.008 to 2 micrometer diameter range and to collect for us impactor samples of particles larger than about 0.02 gm. In the first year, we conducted laboratory studies related to particulate deposition patterns on our collection substrates, and have performed the analysis of many ASHOE/MAESA aerosol samples from 1994 using analytical electron microscopy (AEM). We have been building an "aerosol climatology" with these data that documents the types and relative abundances of particles observed at different latitudes and altitudes. The second year (and non-funded extension periods) saw continued analyses of impactor aerosol samples, including more ASHOE/MAESA samples, some northern hemisphere samples from the NASA Stratospheric Photochemistry Aerosols and Dynamics Expedition (SPADE) program for comparison, and a few aerosol samples from the NASA Stratospheric TRacers of Atmospheric Transport (STRAT) program. A high-resolution field emission microscope was used for the analysis and re-analysis of a number of samples to determine if this instrument was superior in performance to our conventional electron microscope. In addition, some basic laboratory studies were conducted to determine the minimum detectable and analyzable particle size for different types of aerosols. In all, 61 aerosol samples were analyzed, with a total of over 30,000 individual particle analyses. In all analyzed samples, sulfate particles comprised the major aerosol number fraction. It must be stressed that particles composed of more than one species, for example sulfate and organic carbon, were classified

  3. Development and characterization of an ice-selecting pumped counterflow virtual impactor (IS-PCVI) to study ice crystal residuals

    NASA Astrophysics Data System (ADS)

    Hiranuma, Naruki; Möhler, Ottmar; Kulkarni, Gourihar; Schnaiter, Martin; Vogt, Steffen; Vochezer, Paul; Järvinen, Emma; Wagner, Robert; Bell, David M.; Wilson, Jacqueline; Zelenyuk, Alla; Cziczo, Daniel J.

    2016-08-01

    Separation of particles that play a role in cloud activation and ice nucleation from interstitial aerosols has become necessary to further understand aerosol-cloud interactions. The pumped counterflow virtual impactor (PCVI), which uses a vacuum pump to accelerate the particles and increase their momentum, provides an accessible option for dynamic and inertial separation of cloud elements. However, the use of a traditional PCVI to extract large cloud hydrometeors is difficult mainly due to its small cut-size diameters (< 5 µm). Here, for the first time we describe a development of an ice-selecting PCVI (IS-PCVI) to separate ice in controlled mixed-phase cloud system based on the particle inertia with the cut-off diameter ≥ 10 µm. We also present its laboratory application demonstrating the use of the impactor under a wide range of temperature and humidity conditions. The computational fluid dynamics simulations were initially carried out to guide the design of the IS-PCVI. After fabrication, a series of validation laboratory experiments were performed coupled with the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) expansion cloud simulation chamber. In the AIDA chamber, test aerosol particles were exposed to the ice supersaturation conditions (i.e., RHice > 100 %), where a mixture of droplets and ice crystals was formed during the expansion experiment. In parallel, the flow conditions of the IS-PCVI were actively controlled, such that it separated ice crystals from a mixture of ice crystals and cloud droplets, which were of diameter ≥ 10 µm. These large ice crystals were passed through the heated evaporation section to remove the water content. Afterwards, the residuals were characterized with a suite of online and offline instruments downstream of the IS-PCVI. These results were used to assess the optimized operating parameters of the device in terms of (1) the critical cut-size diameter, (2) the transmission efficiency and (3) the counterflow

  4. KSC-05PD-0114

    NASA Technical Reports Server (NTRS)

    2005-01-01

    the Fischer Assembly building at Ball Aerospace in Boulder, Colo. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3- foot projectile (impactor) to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.

  5. A high-efficiency, low-bias method for extracting particulate matter from filter and impactor substrates

    NASA Astrophysics Data System (ADS)

    Bein, K. J.; Wexler, A. S.

    2014-06-01

    Atmospheric particles are frequently collected onto filter and impactor substrates for studies related to the composition, health effects and climate impact of ambient particulate matter (PM). Many of these studies require extraction of that PM from the substrates but available methods have low extraction efficiencies that may lead to compositional and thus toxicity bias. Here, novel PM extraction methods are presented that (a) maximize extraction efficiency, (b) minimize compositional biases in extracted PM, relative to sampled PM and (c) minimize extraction artifacts. Method development was based upon strengths and weaknesses of existing SOPs and current requirements in the field of aerosol health effects research. Extraction objectives were accomplished using a combination of sonication in solvents of varying polarity, selective filtration, liquid-liquid extraction of water-based extracts, solvent removal and final reconstitution of the total extracted PM. Relying largely on intensive gravimetric analyses and comparison to existing SOPs, the new technique has been fully validated on nearly 40 different size-segregated, source-oriented samples collected during two separate seasons in Fresno, CA. Compared to existing methods, and depending on the source, compositionally-specific increases in extraction efficiencies of 10-40% and 20-50% were obtained for the ultrafine and submicron fine PM fractions, respectively, indicating significant increases in total extraction efficiency and significant decreases in compositional bias.

  6. Physics Based Reaction Burn Model Prediction of Reaction Initiation and Growth in RDX for Thin and Thick Impactor

    NASA Astrophysics Data System (ADS)

    Dwivedi, Sunil; Horie, Yasuyuki

    2011-06-01

    PBRB model for reactive composites simulates the reaction initiation and growth leading to detonation with built-in models for multiple individual as well as coupled phenomena: pre-existing statistical pore distribution, energy dissipation during shock loading and hot spot formations, surface temperature increase of the planar pore surfaces, surface reaction by sublimation, gas phase reaction, gas phase temperature rise and reverse heat flow to the pore surface aiding the surface reaction, solid phase heat conduction, etc. 1D idealized hot spot cell (1DHSC) version of the 3D PBRB model has been converted to a vectorized EOS form for the first time. Results validating the model with the pop plot of RDX in agreement with data through simulation of an assumed plate impact experiment will be presented. In addition, the effect of the surface sublimation model parameters on the rate of reaction, detonation shock pressure, and von-Neumann's peak for thin and thick inert impactor will be presented. We acknowledge Dr. Betsy Rice (ARL), Dr. Suhithi Peiris (DTRA) and Dr. John Brennan (ARL) for their support and discussion. This work is supported by Eglin AFB contract FA8651-08-0108/027 and in part by DTRA contract HDTRA-1-10-1-0035.

  7. Ice Nuclei in Mid-Latitude Cirrus: Preliminary Results from a New Counterflow Virtual Impactor (CVI) Aircraft Inlet

    NASA Astrophysics Data System (ADS)

    Froyd, K. D.; Cziczo, D. J.; Murphy, D. M.; Kulkarni, G.; Lawson, P.

    2011-12-01

    Cirrus cloud properties are strongly governed by the mechanism of ice particle formation and by the number and effectiveness of ambient ice nuclei. Airborne measurements of ice nuclei reveal new nucleation mechanisms, provide constraints on microphysical models, and guide laboratory investigations. For over two decades the Counterflow Virtual Impactor (CVI) inlet has remained the prevailing approach for sampling cloud particles to measure ice nuclei from an aircraft platform. However, traditional CVI inlets have fundamental limitations when operating on high speed aircraft, where only a small fraction of ambient cloud particles are typically sampled. A novel 'folded' CVI was constructed and deployed during the NASA MACPEX 2011 campaign. The flow design of this inlet effectively doubles the CVI length and thereby increases the size range of captured cirrus particles. Additional design elements such as an internal vortex flow, a neon carrier gas, and an infrared laser further improve the capture and evaporation of ice crystals. Preliminary results of ice nuclei composition measured by the PALMS single-particle mass spectrometer are presented from the MACPEX campaign. Examples of ice nuclei from mid-latitude cirrus are shown, including mineral dust, organic-rich aerosol with amine and diacid components, and lead-containing aerosol.

  8. Tension strength of a thick graphite/epoxy laminate after impact by a 1/2-in. radius impactor

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.; Illg, W.; Garber, D. P.

    1986-01-01

    NASA is developing graphite/epoxy filament-wound cases for solid rocket motors of the space shuttle. They are wet-wound with AS4W graphite fiber and HBRF-55A epoxy. The membrane region is about 1.4 inches thick. Two 30-inch-diameter by 12-inch-long cylinders were impacted every two inches of circumference with 1/2-inch radius impactors that were dropped from various heights. One cylinder was empty and the other was filled with inert propellant. Two-inch-wide test specimens were cut from the cylinders. Each was centered on an impact site. The specimens were x-rayed and loaded to failure in uniaxial tension. Rigid body mechanics and the Hertz law were used to predict impact force, local deformations, contact diameters, and contact pressures. The depth of impact damage was predicted using Love's solution for pressure applied on part of the boundary of a semi-infinite body. The predictions were reasonably good. The strengths of the impacted specimens were reduced by as much as 37 percent without visible surface damage. Even the radiographs did not reveal the nonvisible damage.

  9. Siderophile elements in brecciated HED meteorites and the nature of projectile materials in HED meteorites

    NASA Astrophysics Data System (ADS)

    Shirai, N.; Okamoto, C.; Yamaguchi, A.; Ebihara, M.

    2016-03-01

    Petrological, mineralogical and geochemical studies were performed on five brecciated HED meteorites (ALH 76005, EET 92003, LEW 85300, LEW 87026 and GRO 95633) in order to elucidate the nature of impactors on the HED parent body. Some brecciated HED meteorites contain exotic materials such as FeNi-metal grains with low Co/Ni ratios (ALH 76005, EET 92003 and GRO 95633) and carbonaceous chondrite clasts (LEW 85300) in a clastic and/or impact melt matrix. Such exotic materials were incorporated during brecciation. Platinum group element (PGE) abundances vary significantly (CI × 0.002-0.05), but are higher than those of pristine rocks from the HED parent body. The PGE ratios for the five HED meteorites are inconsistent with each other, implying that the impactor components of each HED meteorites are different from each other. The various PGE ratios are consistent with those for metals from chondrites and iron meteorites, and carbonaceous chondrites. This study provides the evidence that IAB and IVA iron meteorites, and carbonaceous chondrites (CM, CO, CV, CK, CB and CR), ordinary chondrites (L and H) and enstatite chondrite (EL) are candidates of the impactor materials on the HED parent body. It is highly probable that significant amounts of siderophile elements were incorporated into the inner solar system objects like the HED parent body from both chondritic materials and differentiated materials like iron meteorites during heavy bombardment. The HED meteorites in this study and metals from mesosiderite have different Pd/Ir ratios, probably implying that HED meteorites and mesosiderites formed either at distinct settings on one common parent body or on similar parent bodies.

  10. Fabrication of graded density impactor via underwater shock wave and quasi-isentropic compression testing at two-stage gas gun facility

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Xiaojie; Hokamoto, Kazuyuki

    2014-12-01

    We show direct evidence that underwater shock wave enables us to bond multithin plates with flat, parallel, and high-strength interfaces, which are key requirements for functionally graded material (also called graded density impactor). This phenomenon is ascribed to the super short duration of the high-speed underwater shock wave, reducing the surface tension, diffusion, evaporation, deposition, and viscous flow of matter. Thin magnesium, aluminum, titanium, copper, and molybdenum foils were welded together and designed with the increase in density. Experimental evidence and numerical simulation show that well bonding between the multilayer structures. Microstructure examinations reveal that the dominant interfacial form shifts from waviness to linearity. Graded density impactor with multilayer structure is proved that can produce quasi-isentropic compression in two-stage gas gun experiment with a designed pressure loading profile, which suggests a feasible method to simulate the conditions we want to study that were previously inaccessible in a precisely controlled laboratory environment.

  11. Spreadsheet application showing the proper elevation angle, points of shot and impact of a projectile

    NASA Astrophysics Data System (ADS)

    Benacka, Jan

    2015-05-01

    This paper provides the formula for the elevation angle at which a projectile has to be fired in a vacuum from a general position to hit a target at a given distance. A spreadsheet application that models the trajectory is presented, and the problem of finding the points of shot and impact of a projectile moving in a vacuum if three points of the trajectory are known is solved and modelled by another interactive application. A Gaussian elimination method is used to solve the system of linear equations that gives the trajectory parameters. These applications were developed with 30 high-school students, who were given a questionnaire to find out their opinion of the lessons.

  12. Bombardment of planetary rings by meteoroids - General formulation and effects of Oort Cloud projectiles

    SciTech Connect

    Cuzzi, J.N.; Durisen, R.H. Indiana Univ., Bloomington )

    1990-04-01

    A general solution is obtained for the angular distribution of the intensity and velocity of interplanetary projectiles impinging on a planetary ring system. Three significant results emerge from the solution: (1) a variation with orbital longitude is demonstrated in the impact velocity-weighted impact rate of the planetary rings' cometary meteoroids; (2) the angular distribution of ejecta intensity due to the bombardment of a planetary ring by interplanetary meteoroids is determined; and (3) the radial drift velocity due to both simple mass-loading and aberration-induced asymmetry in the impact rate is calculated for a planetary ring of arbitrary optical depth. Attention is given to results for projectiles with Oort Cloud-type orbits. 40 refs.

  13. Bombardment of planetary rings by meteoroids - General formulation and effects of Oort Cloud projectiles

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Durisen, Richard H.

    1990-01-01

    A general solution is obtained for the angular distribution of the intensity and velocity of interplanetary projectiles impinging on a planetary ring system. Three significant results emerge from the solution: (1) a variation with orbital longitude is demonstrated in the impact velocity-weighted impact rate of the planetary rings' cometary meteoroids; (2) the angular distribution of ejecta intensity due to the bombardment of a planetary ring by interplanetary meteoroids is determined; and (3) the radial drift velocity due to both simple mass-loading and aberration-induced asymmetry in the impact rate is calculated for a planetary ring of arbitrary optical depth. Attention is given to results for projectiles with Oort Cloud-type orbits.

  14. CHRONICALLY EMBEDDED LEAD PROJECTILES IN WILDLIFE: A CASE SERIES INVESTIGATING THE POTENTIAL FOR LEAD TOXICOSIS.

    PubMed

    LaDouceur, Elise E B; Kagan, Rebecca; Scanlan, Michael; Viner, Tabitha

    2015-06-01

    Research has demonstrated that intramuscularly embedded lead in humans and rats may cause direct plumbism, albeit rarely, and has identified risk factors to this end. To the authors' knowledge, this has not been investigated in wildlife, despite a high incidence of embedded lead in these animals secondary to cynegetic activities. Fourteen wildlife cases submitted to the National Fish and Wildlife Forensics Laboratory for cause-of-death determination had chronically embedded lead projectiles that were unrelated to the cause of death. Tissue lead levels were measured in all cases and revealed clinically significant hepatic lead levels in two cases. The results corroborate comparative literature and suggest that embedded lead fragments carry a low risk for direct plumbism, even in the face of risk factors such as fractures, inflammation, and projectile fragmentation. Wildlife morbidity and mortality from embedded lead is more commonly realized secondary to incidental ingestion and ballistic trauma rather than by direct toxicity.

  15. Investigating the Sources and Timing of Projectiles Striking the Lunar Surface

    NASA Technical Reports Server (NTRS)

    Joy, K. H.; Kring, D. A.; Zolensky, M. E.; McKay, D. S.; Ross, D. K.

    2011-01-01

    The lunar surface is exposed to bombardment by asteroids, comets, and debris from them. Surviving fragments of those projectiles in the lunar regolith provide a direct measure of the sources of exogenous material delivered to the Moon. Con-straining the temporal flux of their delivery will directly address key questions about the bombardment history of the inner Solar System. Regolith breccias, which are consolidated samples of the lunar regolith, were closed to further impact processing at the time they were assembled into rocks [1]. They are, therefore, time capsules of impact bombardment at different times through lunar history. Here we investigate the impact archive preserved in the Apollo 16 regolith breccias and compare this record to evidence of projectile species in other lunar samples.

  16. A NASTRAN investigation of simulated projectile damage effects on a UH-1B tail boom model

    NASA Technical Reports Server (NTRS)

    Futterer, A. T.

    1980-01-01

    A NASTRAN model of a UH-1B tail boom that had been designed for another project was used to investigate the effect on structural integrity of simulated projectile damage. Elements representing skin, and sections of stringers, longerons and bulkheads were systematically deleted to represent projectile damage. The structure was loaded in a manner to represent the flight loads that would be imposed on the tail boom at a 130 knot cruise. The deflection of four points on the rear of the tail boom relative to the position of these points for the unloaded, undamaged condition of the tail boom was used as a measure of the loss of structural rigidity. The same procedure was then used with the material properties of the aluminum alloys replaced with the material properties of T300/5208 high strength graphite/epoxy fibrous composite material, (0, + or - 45, 90)s for the skin and (0, + or - 45)s for the longerons, stringers, and bulk heads.

  17. Evidence of strong projectile-target-core interaction in single ionization of neon by electron impact

    SciTech Connect

    Yan, S.; Zhang, P.; Xu, S.; Ma, X.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Liu, H. P.

    2010-11-15

    The momentum distributions of recoil ions were measured in the single ionization of neon by electron impact at incident energies between 80 and 2300 eV. It was found that there are a noticeable number of recoil ions carrying large momenta, and the relative contributions of these ions becomes more pronounced with the further decrease of incident electron energy. These observed behaviors indicate that there is a strong projectile-target-core interaction in the single-ionization reaction. By comparing our results with those of electron-neon elastic scattering, we concluded that the elastic scattering of the projectile electron on the target core plays an important role at low and intermediate collision energies.

  18. Symmetric eikonal model for projectile-electron excitation and loss in relativistic ion-atom collisions

    SciTech Connect

    Voitkiv, A. B.; Najjari, B.; Shevelko, V. P.

    2010-08-15

    At impact energies > or approx. 1 GeV/u the projectile-electron excitation and loss occurring in collisions between highly charged ions and neutral atoms is already strongly influenced by the presence of atomic electrons. To treat these processes in collisions with heavy atoms we generalize the symmetric eikonal model, used earlier for considerations of electron transitions in ion-atom collisions within the scope of a three-body Coulomb problem. We show that at asymptotically high collision energies this model leads to an exact transition amplitude and is very well suited to describe the projectile-electron excitation and loss at energies above a few GeV/u. In particular, by considering a number of examples we demonstrate advantages of this model over the first Born approximation at impact energies of {approx}1-30 GeV/u, which are of special interest for atomic physics experiments at the future GSI facilities.

  19. Resistance of plain and steel fiber-reinforced concrete slabs against short ogival projectiles impact

    NASA Astrophysics Data System (ADS)

    Mu, ZhongCheng; Zhang, Wei; Pang, PaoJun; Yang, ZhenQi

    2010-03-01

    Due to the enhanced energy absorption characteristics, the steel fiber-reinforced concrete (SFPC) structures gains more and more attention in the civilian and military ballistic protection structures when comparing with the plain concrete (PC) ones. By comparison on the penetration depth, the crater volume on impact face of the target and the debris cloud topography, the resistance of PC and SFPC slabs against projectiles impacting was investigated experimentally in a two-stage light-gas gun. In order to more widespread understand the effect of steel fibers against projectiles impacting, five different types of concrete slabs were done in the range of unconfined compressive strength from ordinary to high. Through the analysis of the test results it was found that the incorporation of steel fibers in the concrete reduced the crater diameter and restrained the initiation and propagation of cracking, but did not have a significant effect on the penetration depth.

  20. Resistance of plain and steel fiber-reinforced concrete slabs against short ogival projectiles impact

    NASA Astrophysics Data System (ADS)

    Mu, Zhongcheng; Zhang, Wei; Pang, Paojun; Yang, Zhenqi

    2009-12-01

    Due to the enhanced energy absorption characteristics, the steel fiber-reinforced concrete (SFPC) structures gains more and more attention in the civilian and military ballistic protection structures when comparing with the plain concrete (PC) ones. By comparison on the penetration depth, the crater volume on impact face of the target and the debris cloud topography, the resistance of PC and SFPC slabs against projectiles impacting was investigated experimentally in a two-stage light-gas gun. In order to more widespread understand the effect of steel fibers against projectiles impacting, five different types of concrete slabs were done in the range of unconfined compressive strength from ordinary to high. Through the analysis of the test results it was found that the incorporation of steel fibers in the concrete reduced the crater diameter and restrained the initiation and propagation of cracking, but did not have a significant effect on the penetration depth.

  1. Dynamics of formation of K-hole fractions of sulfur projectiles inside a carbon foil

    SciTech Connect

    Braziewicz, J.; Majewska, U.; Slabkowska, K.; Polasik, M.; Fijal, I.; Jaskola, M.; Korman, A.; Czarnacki, W.; Chojnacki, S.; Kretschmer, W.

    2004-06-01

    The K{alpha} and K{beta} satellite and hypersatellite x-ray lines emitted by highly ionized sulfur projectiles passing with energies from 65 MeV up to 122 MeV through carbon foils of thickness of 15-210 {mu}g cm{sup -2} have been recorded using a Si(Li) detector. The additional hypersatellite Ky{sup h} peak proves that for such high energies of the sulfur ions very high subshells (4p and 5p) could be occupied. In order to study the dynamics of formation of K-shell vacancy fractions of sulfur projectiles passing through a carbon foil the dependence of sulfur K x-ray production cross sections on foil thickness has been examined separately for each recorded line using the three component model. For each projectile energy the values of K-shell hole production cross sections and K-shell electron capture cross sections (both common for all recorded x-ray lines in the case of each projectile energy) have been fitted, as well as the specific values (for each recorded x-ray line) of K-shell hole filling cross sections, which are directly connected with average lifetimes of appropriate states of sulfur ions. The obtained ''experimental'' values of K-shell vacancy production cross sections are much higher than the theoretical predictions. This suggests that apart from the ionization process the excitation from K shell into higher shells is responsible for a production of K-shell vacancies, which has been confirmed by recent classical trajectory Monte Carlo calculations.

  2. HIFI: a computer code for projectile fragmentation accompanied by incomplete fusion

    SciTech Connect

    Wu, J.R.

    1980-07-01

    A brief summary of a model proposed to describe projectile fragmentation accompanied by incomplete fusion and the instructions for the use of the computer code HIFI are given. The code HIFI calculates single inclusive spectra, coincident spectra and excitation functions resulting from particle-induced reactions. It is a multipurpose program which can calculate any type of coincident spectra as long as the reaction is assumed to take place in two steps.

  3. From boron carbide to glass: Absorption of an elongated high-speed projectile in brittle materials

    NASA Astrophysics Data System (ADS)

    Rumyantsev, B. V.

    2016-09-01

    Penetration into boron carbide of an elongated high-speed projectile in the form of a copper jet produced by an explosion of a cumulative charge is studied. The efficiency of absorption of a copper jet in different brittle materials for evaluating their protective ability is compared. Conditions for the absence of the influence of the lateral unloading wave on the penetration zone, which provide the minimum penetration depth, are determined.

  4. Generation of dust projectiles passing over an obstacle in the plasma sheath

    SciTech Connect

    Ticos, Catalin M.; Stoica, Daniel S.; Delzanno, Gian Luca

    2012-08-15

    Dust projectiles were produced in a radio-frequency plasma by increasing 6-fold the radio-frequency power put into the discharge. The initial static dust particles were observed to gain speed while moving away from the confining region and escaped from the inter-electrode space on a ballistic-like trajectory. Single-grain dynamics simulations indicated that the dust particles were accelerated by changes induced in the sheath electric field profile.

  5. Optical fiber-based system for continuous measurement of in-bore projectile velocity.

    PubMed

    Wang, Guohua; Sun, Jinglin; Li, Qiang

    2014-08-01

    This paper reports the design of an optical fiber-based velocity measurement system and its application in measuring the in-bore projectile velocity. The measurement principle of the implemented system is based on Doppler effect and heterodyne detection technique. The analysis of the velocity measurement principle deduces the relationship between the projectile velocity and the instantaneous frequency (IF) of the optical fiber-based system output signal. To extract the IF of the fast-changing signal carrying the velocity information, an IF extraction algorithm based on the continuous wavelet transforms is detailed. Besides, the performance of the algorithm is analyzed by performing corresponding simulation. At last, an in-bore projectile velocity measurement experiment with a sniper rifle having a 720 m/s muzzle velocity is performed to verify the feasibility of the optical fiber-based velocity measurement system. Experiment results show that the measured muzzle velocity is 718.61 m/s, and the relative uncertainty of the measured muzzle velocity is approximately 0.021%.

  6. Optical fiber-based system for continuous measurement of in-bore projectile velocity

    NASA Astrophysics Data System (ADS)

    Wang, Guohua; Sun, Jinglin; Li, Qiang

    2014-08-01

    This paper reports the design of an optical fiber-based velocity measurement system and its application in measuring the in-bore projectile velocity. The measurement principle of the implemented system is based on Doppler effect and heterodyne detection technique. The analysis of the velocity measurement principle deduces the relationship between the projectile velocity and the instantaneous frequency (IF) of the optical fiber-based system output signal. To extract the IF of the fast-changing signal carrying the velocity information, an IF extraction algorithm based on the continuous wavelet transforms is detailed. Besides, the performance of the algorithm is analyzed by performing corresponding simulation. At last, an in-bore projectile velocity measurement experiment with a sniper rifle having a 720 m/s muzzle velocity is performed to verify the feasibility of the optical fiber-based velocity measurement system. Experiment results show that the measured muzzle velocity is 718.61 m/s, and the relative uncertainty of the measured muzzle velocity is approximately 0.021%.

  7. Hypervelocity projectile acceleration with a railgun using a two-stage gas gun injector

    NASA Astrophysics Data System (ADS)

    Hawke, R. S.

    1989-04-01

    Unique potential applications of electromagnetic railguns [R.S. Hawke, IEEE Trans. Nucl. NS-28 (2) (1981) 1542] have motivated a decade of continuous development throughout the world. This effort has led to routine acceleration of projectiles of from 1 g to about 1 kg, to velocities of nearly 4 km/s. Attempts to reach higher velocities have met with problems in the 6- to 8-km/s range [J.V. Parker, Proc. 4th Symp. on Electromagnetic Launch Tech., Austin, TX, 1988, to be published in IEEE Trans. Mag.]. The principal problem is "restrike", which causes shunting of the propulsive plasma armature by the formation of a second plasma short circuit in the breech region of the railgun. One means of impeding restrike is the use of a two-stage light-gas gun (2SLGG) as a projectile injector. A joint development project was initiated in early 1986 between the Sandia National Laboratories Albuquerque (SNLA) and the Lawrence Livermore National Laboratory (LLNL). The project is based on the use of a 2SLGG to inject projectiles at about 7 km/s. The injection gas is hydrogen, which serves to inhibit formation of the secondary arc and to minimize barrel ablation and armature contamination. Results and status of this work are discussed.

  8. Study on the oblique perforation of thin steel pates by flat and ogival projectiles

    NASA Astrophysics Data System (ADS)

    Guo, Zitao; Zhang, Wei; Ren, Peng; Hypervelocity Impact Research Center Collaboration

    This paper presents a numerical study on the oblique perforation of thin steel plates. Numerical simulations of 1 mm single A3 steel plates impacted by flat and ogival projectiles at 0°, 15°, 30°, 45° and 60° angles over a range of velocities from 50 to 250 m/s were performed using the finite element code ABAQUS, where a modified versions of the J-C constitutive relation and fracture criterion based on a series of quasi-static and dynamic tensile tests with smooth and notched axisymmetric specimens were adopted to approximate behaviors of target material. Corresponding oblique perforation experiments were also conducted in order to be compared and calibrated. Initial-residual velocity curves and ballistic limits of targets under different angle impact were determined and compared, and the effects of projectile nose shape and obliquity on the ballistic resistance and failure models of targets were investigated. Results show that the nose shape of the projectile and oblique angles severely affected both the energy absorption and the failure mode of the target plate during perforation. Good agreement is found between the numerical simulations and experimental results.

  9. Asymmetric material impact: Achieving free surfaces velocities nearly double that of the projectile

    SciTech Connect

    Aslam, Tariq; Dattelbaum, Dana; Gustavsen, Richard; Scharff, Robert; Byers, Mark

    2015-05-19

    Hypervelocity impact speeds are often limited by practical considerations in guns and explosive driven systems. In particular, for gas guns (both powder driven and light gas guns), there is the general trend that higher projectile speeds often come at the expense of smaller diameters, and thus less time for examining shock phenomena prior to two dimensional release waves affecting the observed quantities of interest. Similarly, explosive driven systems have their own set of limiting conditions due to limitations in explosive energy and size of devices required as engineering dimensions increase. The focus in this study is to present a methodology of obtaining free surface velocities well in excess of the projectile velocity. The key to this approach is in using a high impedance projectile that impacts a series of progressively lower impedance materials. The free surface velocity (if they were separated) of each of the progressively lower impedance materials would increase for each material. The theory behind this approach, as well as experimental results are presented.

  10. Asymmetric material impact: Achieving free surfaces velocities nearly double that of the projectile

    DOE PAGES

    Aslam, Tariq; Dattelbaum, Dana; Gustavsen, Richard; Scharff, Robert; Byers, Mark

    2015-05-19

    Hypervelocity impact speeds are often limited by practical considerations in guns and explosive driven systems. In particular, for gas guns (both powder driven and light gas guns), there is the general trend that higher projectile speeds often come at the expense of smaller diameters, and thus less time for examining shock phenomena prior to two dimensional release waves affecting the observed quantities of interest. Similarly, explosive driven systems have their own set of limiting conditions due to limitations in explosive energy and size of devices required as engineering dimensions increase. The focus in this study is to present a methodologymore » of obtaining free surface velocities well in excess of the projectile velocity. The key to this approach is in using a high impedance projectile that impacts a series of progressively lower impedance materials. The free surface velocity (if they were separated) of each of the progressively lower impedance materials would increase for each material. The theory behind this approach, as well as experimental results are presented.« less

  11. Morphology and chemistry of projectile residue in small experimental impact craters

    NASA Technical Reports Server (NTRS)

    Horz, F.; Fechtig, H.; Janicke, J.; Schneider, E.

    1983-01-01

    Small-scale impact craters (5-7 mm in diameter) were produced with a light gas gun in high purity Au and Cu targets using soda lime glass (SL) and man-made basalt glass (BG) as projectiles. Maximum impact velocity was 6.4 km/s resulting in peak pressures of approximately 120-150 GPa. Copious amounts of projectile melts are preserved as thin glass liners draping the entire crater cavity; some of this liner may be lost by spallation, however. SEM investigations reveal complex surface textures including multistage flow phenomena and distinct temporal deposition sequences of small droplets. Inasmuch as some of the melts were generated at peak pressures greater than 120 GPa, these glasses represent the most severely shocked silicates recovered from laboratory experiments to date. Major element analyses reveal partial loss of alkalis; Na2O loss of 10-15 percent is observed, while K2O loss may be as high as 30-50 percent. Although the observed volatile loss in these projectile melts is significant, it still remains uncertain whether target melts produced on planetary surfaces are severely fractionated by selective volatilization processes.

  12. Determine ISS Soyuz Orbital Module Ballistic Limits for Steel Projectiles Hypervelocity Impact Testing

    NASA Technical Reports Server (NTRS)

    Lyons, Frankel

    2013-01-01

    A new orbital debris environment model (ORDEM 3.0) defines the density distribution of the debris environment in terms of the fraction of debris that are low-density (plastic), medium-density (aluminum) or high-density (steel) particles. This hypervelocity impact (HVI) program focused on assessing ballistic limits (BLs) for steel projectiles impacting the enhanced Soyuz Orbital Module (OM) micrometeoroid and orbital debris (MMOD) shield configuration. The ballistic limit was defined as the projectile size on the threshold of failure of the OM pressure shell as a function of impact speeds and angle. The enhanced OM shield configuration was first introduced with Soyuz 30S (launched in May 2012) to improve the MMOD protection of Soyuz vehicles docked to the International Space Station (ISS). This test program provides HVI data on U.S. materials similar in composition and density to the Russian materials for the enhanced Soyuz OM shield configuration of the vehicle. Data from this test program was used to update ballistic limit equations used in Soyuz OM penetration risk assessments. The objective of this hypervelocity impact test program was to determine the ballistic limit particle size for 440C stainless steel spherical projectiles on the Soyuz OM shielding at several impact conditions (velocity and angle combinations). This test report was prepared by NASA-JSC/ HVIT, upon completion of tests.

  13. Experimental and Numerical Study of Water-Filled Vessel Impacted by Flat Projectiles

    NASA Astrophysics Data System (ADS)

    Ren, Peng; Zhang, Wei; Guo, Zitao; Wei, Gang

    2011-06-01

    To understand the failure patterns and impact resistance of watertight vessel, a flat-nosed projectile was accelerated by a two-stage light gas gun against a vessel filled with water which was placed in an air-filled tank. The targets were the 5A06 aluminum which were installed on two opposite sides of the vessel. The penetration process was recorded by a digital high-speed camera. In order to compare, numerical simulations for the vessel with and without water impacted by projectiles were conducted by AUTODYN-3D. The material parameters of targets and projectiles used in the simulation were obtained from several previous studies. The result indicated that experimental and numerical results were in good agreement. Numerical simulations were capable to capture the main physical behavior. It was also found that the impact resistance of targets in the water-filled vessel was lager than that of the empty vessel. Tearing was the main failure models of the water-filled vessel targets which was different from that of the empty vessel where the shear plugging was in dominate.

  14. Experimental and Numerical Study of Water-Filled Vessel Impacted by Flat Projectiles

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Ren, Peng; Huang, Wei; Gao, Yubo

    2013-06-01

    To understand the failure patterns and impact resistance of watertight vessel, a flat-nosed projectile was accelerated by a two-stage light gas gun against a vessel filled with water which was placed in an air-filled tank. The targets were the 5A06 aluminum which were installed on two opposite sides of the vessel. The penetration process was recorded by a digital high-speed camera. In order to compare, numerical simulations for the vessel with and without water impacted by projectiles were conducted by AUTODYN-3D. The material parameters of targets and projectiles used in the simulation were obtained from several previous studies. The result indicated that experimental and numerical results were in good agreement. Numerical simulations were capable to capture the main physical behavior. It was also found that the impact resistance of targets in the water-filled vessel was lager than that of the empty vessel. Tearing was the main failure models of the water-filled vessel targets which was different from that of the empty vessel where the shear plugging was in dominate. National Natural Science Foundation of China (NO.:11072072).

  15. Influence of impact conditions on plasma generation during hypervelocity impact by aluminum projectile

    NASA Astrophysics Data System (ADS)

    Song, Weidong; Lv, Yangtao; Li, Jianqiao; Wang, Cheng; Ning, Jianguo

    2016-07-01

    For describing hypervelocity impact (relative low-speed as related to space debris and much lower than travelling speed of meteoroids) phenomenon associated with plasma generation, a self-developed 3D code was advanced to numerically simulate projectiles impacting on a rigid wall. The numerical results were combined with a new ionization model which was developed in an early study to calculate the ionized materials during the impact. The calculated results of ionization were compared with the empirical formulas concluded by experiments in references and a good agreement was obtained. Then based on the reliable 3D numerical code, a series of impacts with different projectile configurations were simulated to investigate the influence of impact conditions on hypervelocity impact generated plasma. It was found that the form of empirical formula needed to be modified. A new empirical formula with a critical impact velocity was advanced to describe the velocity dependence of plasma generation and the parameters of the modified formula were ensured by the comparison between the numerical predictions and the empirical formulas. For different projectile configurations, the changes of plasma charges with time are different but the integrals of charges on time almost stayed in the same level.

  16. Numerical and experimental study of the impact of small caliber projectiles on ballistic soap

    NASA Astrophysics Data System (ADS)

    Dyckmans, G.; Ndompetelo, N.; Chabotier, A.

    2003-09-01

    Terminal ballistic deals with interactions between targets and projectiles. One of the areas of interest is wound ballistics, where one studies the interaction between a projectile (a bullet or a fragment) and the human body. Soap and gelatin are commonly used materials for simulating soft human body tissue in wound ballistics experiments. They are to be considered as tools for comparing the effectiveness of different projectiles. The department of weapon systems & ballistics of the Belgian Royal Military Academy is examining to what extent the Autodyn hydrocode can be used as a numerical tool for simulating the penetration of military bullets into ballistic soap. This article presents the philosophy and the results of the project's first phase i.e. the use of Autodyn for simulating the penetration of a steel sphere into a block of ballistic soap as a result of a normal impact at different velocities. A series of experiments (real firings) have been performed in the laboratory of the department. They serve as a reference and validation tool for the numerical approach. The latter is characterized by the specific problem of accurate material modeling of the soap. The application of a stepwise parametric study of material models and parameters has resulted in numerical simulations which fit quite well with experiments.

  17. Dynamics of hypervelocity jetting during oblique impacts of spherical projectiles investigated via ultrafast imaging

    NASA Astrophysics Data System (ADS)

    Kurosawa, Kosuke; Nagaoka, Yoichi; Senshu, Hiroki; Wada, Koji; Hasegawa, Sunao; Sugita, Seiji; Matsui, Takafumi

    2015-07-01

    A series of hypervelocity impact experiments was conducted in a new laboratory at Planetary Exploration Research Center of Chiba Institute of Technology (Japan). We present the results of high-speed imaging observations of impact jetting during blunt-body penetration under oblique impacts. The observations were sampled at a frame rate of 100 ns frame-1, which is much shorter than the characteristic time of projectile penetration under our experimental conditions. The maximum jet velocity was obtained as a function of both impact velocity and the contrast of shock impedance between a projectile and target, enabling us to test theoretical models of impact jetting during oblique impacts of spherical projectiles. We find that the jet velocities measured in this study are much slower than the prediction by the standard theory based on the previous experimental/theoretical results of collisions between two metal plates. A decaying shock pressure during blunt-body penetration is a possible origin of the discrepancy. We also present a new formulation of the jet velocity with the equations of state for realistic materials. The particle velocities of ejected materials from a free surface are calculated using the Riemann invariant along the isentropes and the Tillotson equations of state in this study. Based on the extremely high velocity of the jet, we point out that impact jetting might contribute to chemistry near the ground surface of planets/satellites with a thick atmosphere, such as Titan.

  18. Hypervelocity gun. [using both electric and chemical energy for projectile propulsion

    NASA Technical Reports Server (NTRS)

    Ford, F. C.; Biehl, A. J. (Inventor)

    1965-01-01

    A velocity amplifier system which uses both electric and chemical energy for projectile propulsion is provided in a compact hypervelocity gun suitable for laboratory use. A relatively heavy layer of a tamping material such as concrete encloses a loop of an electrically conductive material. An explosive charge at least partially surrounding the loop is adapted to collapse the loop upon detonation of the charge. A source of electricity charges the loop through two leads, and an electric switch which is activated by the charge explosive charge, disconnects the leads from the source of electricity and short circuits them. An opening in the tamping material extends to the loop and forms a barrel. The loop, necked down in the opening, forms the sabot on which the projectile is located. When the loop is electrically charged and the explosive detonated, the loop is short circuited and collapsed thus building up a magnetic field which acts as a sabot catcher. The sabot is detached from the loop and the sabot and projectile are accelerated to hypervelocity.

  19. Fin gaps and body slots of guided projectiles: Effects, data correlation and modeling

    NASA Astrophysics Data System (ADS)

    Mikhail, Ameer G.

    1987-06-01

    Prior work concerned with the effect of streamwise fin-body gaps unporting effect and body slots on the fin loads of projectiles and missiles in the transonic speed regime of 0.8 less than or = M less than or = 1.2, was reviewed. Experimental data for the gap effects have been analyzed. A correlation established to predict fin normal force losses due to gaps for any fin shape, size, aspect ratio, fitted very well with the data which span a large variation in Reynolds number, body diameter and boundary layer thickness. Although the Mach range for the present model was intended to be 0.8 less than or = M less than or = 1.2, available data indicated its validity in the wider range of 0.7 less than or = M less than or = 1.6. Fifteen cases were used to validate the present gap model. Application of these two corrections to the Copperhead guided projectile was made and a reduction as large as 38% was predicted for the normal force, which was then validated by the experimental data. The present results can be used for estimating fin load losses for the fin design of guided projectiles and missiles, with 5% accuracy, over the intended Mach number range 0.8 less than or = M less than or = 1.2.

  20. Hemispherical Analyser with 2-D PSD for Zero-degree Auger Projectile Spectroscopy

    NASA Astrophysics Data System (ADS)

    Benis, E. P.; Zouros, T. J. M.; Aliabadi, H.; Richard, P.

    Details of a new high gain zero-degree Auger projectile electron spectrograph using a hemispherical analyser and a 2-dimensional position sensitive detector (PSD) with multichannel plates and a resistive anode encoder are presented. A four-element lens mounted at the entrance of the analyser, provides a virtual slit for the incoming electrons by focusing them while at the same time decelerating them to improve their energy resolution. Electrons enter through an aperture at a position R0 which is displaced (along the energy dispersion axis) with respect to the commonly used central entrance position at 1/2 (R1+R2). The analyser has an acceptance energy range of 20% and an energy resolution of 0.9%. An ion-optics trajectory simulation indicates improved focusing properties for this off-center position thus avoiding the need for cumbersome fringing field correction schemes. Test measurements of high resolution projectile Auger spectra produced in 21.7 MeV collisions of F8+ and F7+ projectiles with H2 and He are presented.

  1. Stopping cross sections for N4+-->H at low projectile velocity

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Deumens, Erik; Öhrn, Yngve

    2002-08-01

    We study the time-dependent dynamics of N4+ ions colliding with atomic hydrogen for projectile energies ranging from a fraction of an eV/amu up to 25 keV/amu using the electron-nuclear dynamics (END) formalism. The END theory obtains the electron-nuclear coupled equations of motion from the time-dependent variational principle employing a coherent state parametrization of the wave function. This approach leads to a simultaneous nonadiabatic dynamics of all the electrons and nuclei. We calculate and discuss dynamical trajectories, deflection functions, final charge states, differential cross sections, and energy loss. Quantum effects of the forward peak scattering are emphasized. Due to the strong interaction between the heavy ion and the hydrogen atom, a ``diffuse ion'' (vide infra) is formed, leading to acceleration or energy gain of the projectile. For the case of the electron transfer cross section, we found that it does not follow the Langevin-type cross section at low projectile energies as reported by other methods. Present results show good agreement with available experimental data.

  2. Optical fiber-based system for continuous measurement of in-bore projectile velocity.

    PubMed

    Wang, Guohua; Sun, Jinglin; Li, Qiang

    2014-08-01

    This paper reports the design of an optical fiber-based velocity measurement system and its application in measuring the in-bore projectile velocity. The measurement principle of the implemented system is based on Doppler effect and heterodyne detection technique. The analysis of the velocity measurement principle deduces the relationship between the projectile velocity and the instantaneous frequency (IF) of the optical fiber-based system output signal. To extract the IF of the fast-changing signal carrying the velocity information, an IF extraction algorithm based on the continuous wavelet transforms is detailed. Besides, the performance of the algorithm is analyzed by performing corresponding simulation. At last, an in-bore projectile velocity measurement experiment with a sniper rifle having a 720 m/s muzzle velocity is performed to verify the feasibility of the optical fiber-based velocity measurement system. Experiment results show that the measured muzzle velocity is 718.61 m/s, and the relative uncertainty of the measured muzzle velocity is approximately 0.021%. PMID:25173302

  3. Precision of the all-glass impinger and the andersen microbial impactor for air sampling in solid-waste handling facilities.

    PubMed Central

    Lembke, L L; Kniseley, R N; van Nostrand, R C; Hale, M D

    1981-01-01

    A method was devised to determine the precision of the all-glass impinger and the Andersen six-stage microbial impactor over a wide range of aerosol concentrations like those found in facilities which process solid waste. Simultaneous samples were collected inside a municipal solid-waste recovery system, and the data were treated statistically to estimate the precision of each air-sampling device. All-glass impingers yielded colony counts which indicated a linear relationship between samplers over an observed aerosol concentration of 1.1 X 10(3) to 2.8 X 10(7) colony-forming units per m3 of air. Impactors also yielded colony counts which indicated a linear relationship over an observed aerosol concentration range of 3.9 X 10(3) to 1.9 X 10(5) colony-forming units per m3 of air. The coefficients of variation for the all-glass impinger and the six-stage impactor in an environment with a high and variable dust level were determined to be 0.38 and 0.23, respectively. PMID:7025757

  4. The preservation of fossil biomarkers during meteorite impact events: Experimental evidence from biomarker-rich projectiles and target rocks

    NASA Astrophysics Data System (ADS)

    Parnell, John; Bowden, Stephen; Lindgren, Paula; Burchell, Mark; Milner, Daniel; Price, Mark; Baldwin, Emily C.; Crawford, Ian A.

    2010-08-01

    A Devonian siltstone from Orkney, Scotland, shows survival of biomarkers in high-velocity impact experiments. The biomarkers were detected in ejecta fragments from experiments involving normal incidence of steel projectiles at 5-6kms-1, and in projectile fragments from impact experiments into sand and water at 2-5kms-1. The associated peak shock pressures were calculated to be in the range of 110-147GPa for impacts of the steel projectiles into the siltstone target, and hydrocode simulations are used to show the variation of peak pressure with depth in the target and throughout the finite volume projectiles. Thermally sensitive biomarker ratios, including ratios of hopanoids and steranes, and the methylphenanthrene ratio, showed an increase in thermal maturity in the ejecta, and especially the projectile, fragments. Measurement of absolute concentrations of selected biomarkers indicates that changes in biomarker ratios reflect synthesis of new material rather than selective destruction. Their presence in ejecta and projectile fragments suggests that fossil biomarkers may survive hypervelocity impacts, and that experiments using biomarker-rich rock have high potential for testing survival of organic matter in a range of impact scenarios.

  5. Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part II: Structural stability analyses

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Chen, Xiao-Wei; Fang, Qin; He, Li-Lin

    2014-12-01

    The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile, and the penetration efficiency decreases distinctly. The structural stability of a high-speed projectile non-normally penetrating into concrete and the parametric influences involved are analyzed with the mass abrasion taken into account. By considering the symmetrical or asymmetrical nose abrasion as well as the initial oblique and attacking angles, both the axial and the transverse drag forces acting on the projectile are derived. Based on the ideal elastic-plastic yield criterion, an approach is proposed for predicting the limit striking velocity (LSV) that is the highest velocity at which no yielding failure has occurred and the projectile can still maintain its integral structural stability. Furthermore, some particular penetration scenarios are separately discussed in detail. Based on the engineering model for the mass loss and nose-blunting of ogive-nose projectiles established in Part I of this study, the above approach is validated by several high-speed penetration tests. The analysis on parametric influences indicates that the LSV is reduced with an increase in the asymmetrical nose abrasion, the length-diameter-ratio, and the concrete strength, as well as the oblique and attacking angles. Also, the LSV raises with an increase in the initial caliber-radius-head (CRH) and the dimensionless cartridge thickness of a projectile.

  6. Penetration Experiments with 6061-T6511 Aluminum Targets and Spherical-Nose Steel Projectiles at Striking Velocities Between 0.5 and 3.0 km/s

    SciTech Connect

    Forrestal, M.J.; Piekutowski, A.J.

    1999-02-04

    We conducted depth of penetration experiments with 7.11-mm-diameter, 74.7-mm-long, spherical-nose, 4340 steel projectiles launched into 250-mm-diameter, 6061-T6511 aluminum targets. To show the effect of projectile strength, we used projectiles that had average Rockwell harnesses of R{sub c} = 36.6, 39.5, and 46.2. A powder gun and two-stage, light-gas guns launched the 0.023 kg projectiles at striking velocities between 0.5 and 3.0 km/s. Post-test radiographs of the targets showed three response regions as striking velocities increased: (1) the projectiles remained visibly undeformed, (2) the projectiles permanently deformed without erosion, and (3) the projectiles eroded and lost mass. To show the effect of projectile strength, we compared depth-of-penetration data as a function of striking velocity for spherical-nose rods with three Rockwell harnesses at striking velocities ranging from 0.5 to 3.0 km/s. To show the effect of nose shape, we compared penetration data for the spherical-nose projectiles with previously published data for ogive-nose projectiles.

  7. The motion of an arbitrarily rotating spherical projectile and its application to ball games

    NASA Astrophysics Data System (ADS)

    Robinson, Garry; Robinson, Ian

    2013-07-01

    In this paper the differential equations which govern the motion of a spherical projectile rotating about an arbitrary axis in the presence of an arbitrary ‘wind’ are developed. Three forces are assumed to act on the projectile: (i) gravity, (ii) a drag force proportional to the square of the projectile's velocity and in the opposite direction to this velocity and (iii) a lift or ‘Magnus’ force also assumed to be proportional to the square of the projectile's velocity and in a direction perpendicular to both this velocity and the angular velocity vector of the projectile. The problem has been coded in Matlab and some illustrative model trajectories are presented for ‘ball-games’, specifically golf and cricket, although the equations could equally well be applied to other ball-games such as tennis, soccer or baseball. Spin about an arbitrary axis allows for the treatment of situations where, for example, the spin has a component about the direction of travel. In the case of a cricket ball the subtle behaviour of so-called ‘drift’, particularly ‘late drift’, and also ‘dip’, which may be produced by a slow bowler's off or leg-spin, are investigated. It is found that the trajectories obtained are broadly in accord with those observed in practice. We envisage that this paper may be useful in two ways: (i) for its inherent scientific value as, to the best of our knowledge, the fundamental equations derived here have not appeared in the literature and (ii) in cultivating student interest in the numerical solution of differential equations, since so many of them actively participate in ball-games, and they will be able to compare their own practical experience with the overall trends indicated by the numerical results. As the paper presents equations which can be further extended, it may be of interest to research workers. However, since only the most basic principles of fundamental mechanics are employed, it should be well within the grasp of first

  8. Asteroid Retrieval Mission Concept - Trailblazing Our Future in Space and Helping to Protect Us from Earth Impactors

    NASA Technical Reports Server (NTRS)

    Mazanek, Daniel D.; Brohpy, John R.; Merrill, Raymond G.

    2013-01-01

    The Asteroid Retrieval Mission (ARM) is a robotic mission concept with the goal of returning a small (7 m diameter) near-Earth asteroid (NEA), or part of a large NEA, to a safe, stable orbit in cislunar space using a 50 kW-class solar electric propulsion (SEP) robotic spacecraft (40 kW available to the electric propulsion system) and currently available technologies. The mass of the asteroidal material returned from this mission is anticipated to be up to 1,000 metric tons, depending on the orbit of the target NEA and the thrust-to-weight and control authority of the SEP spacecraft. Even larger masses could be returned in the future as technological capability and operational experience improve. The use of high-power solar electric propulsion is the key enabling technology for this mission concept, and is beneficial or enabling for a variety of space missions and architectures where high-efficiency, low-thrust transfers are applicable. Many of the ARM operations and technologies could also be applicable to, or help inform, planetary defense efforts. These include the operational approaches and systems associated with the NEA approach, rendezvous, and station-keeping mission phases utilizing a low-thrust, high-power SEP spacecraft, along with interacting with, capturing, maneuvering, and processing the massive amounts of material associated with this mission. Additionally, the processed materials themselves (e.g., high-specific impulse chemical propellants) could potentially be used for planetary defense efforts. Finally, a ubiquitous asteroid retrieval and resource extraction infrastructure could provide the foundation of an on call planetary defense system, where a SEP fleet capable of propelling large masses could deliver payloads to deflect or disrupt a confirmed impactor in an efficient and timely manner.

  9. Comparison among filter-based, impactor-based and continuous techniques for measuring atmospheric fine sulfate and nitrate

    NASA Astrophysics Data System (ADS)

    Nie, Wei; Wang, Tao; Gao, Xiaomei; Pathak, Ravi Kant; Wang, Xinfeng; Gao, Rui; Zhang, Qingzhu; Yang, Lingxiao; Wang, Wenxing

    2010-11-01

    Filter-based methods for sampling aerosols are subject to great uncertainty if the gas-particle interactions on filter substrates are not properly handled. Sampling artifacts depend on both meteorological conditions and the chemical mix of the atmosphere. Despite numerous of studies on the subject, very few have evaluated filter-based methods in the Asian environments. This paper reports the results of a comparison of the performances of two filter-based samplers, including a Thermo Anderson Chemical Speciation Monitor (RAAS) and a honeycomb denuder filter-pack system, a Micro Orifice Uniform Deposit Impactor (MOUDI) and a real-time ambient ion monitor (AIM, URG9000B) in measuring atmospheric concentrations of PM 2.5 sulfate and nitrate. Field studies were conducted at an urban site in Jinan, Shandong province, during the winter of 2007 and at a rural site near Beijing in the summer of 2008. The AIM was first compared with the honeycomb denuder filter-pack system which was considered to have minimal sampling artifacts. After some modifications made to it, the AIM showed good performance for both sulfate and nitrate measurement at the two sites and was then used to evaluate other instruments. For the un-denuded RAAS, the extent of sampling artifacts for nitrate on quartz filters was negligible, while that on Teflon filters was also minimal at high nitrate concentrations (>10 μgm -3); however, loss through evaporation was significant (˜75%) at low nitrate concentrations under hot summer conditions. The MOUDI using aluminum substrates suffered a significant loss of nitrate (50-70%) under summer conditions due to evaporation. Considering that the aluminum substrates are still being widely used to obtain size-resolved aerosol compositions because of their low cost and accurate mass weighed, caution should be taken about the potential significant under determination of semi-volatile components such as ammonium nitrate.

  10. The Chicxulub impact at the K-Pg boundary - search for traces of the projectile

    NASA Astrophysics Data System (ADS)

    Deutsch, A.

    2012-04-01

    One of the most interesting problems in the context of the end-Cretaceous Chicxulub impact is the question after the whererabouts of the main mass of the projectile. The nature of this >10 km-sized Chicxulub projectile was constrained by an anomaly in the chromium isotope 54 in the K-Pg deposit at Stevens Klint, Denmark, to a carbonaceous chondrite of type CM2 [1]. About 1.5 % of the estimated mass of the projectile has been detected world-wide in the K-Pg boundary layer; mainly in the form of platinum group elements (PGE) as well as other siderophile elements (Ni, Co ... ). A contamination by or even a major contribution of other "projectile" elements to the K-Pg event bed was rarely proposed. The few examples in the literature (cf. compilation in [2, 3]) used rare earth elements (REE) distribution patterns that are slightly inconsistent with REE patterns typical for the upper continental crust (UCC). Ejecta consisting of UCC target rocks is expected to form the overwhelming mass of the ejecta. In most K-Pg layers, however, the ejecta is diluted or even totally masked by a component of more local origin and with features of high-energy deposition mechanisms. Numerical models [4] indicate a deposition of >500km3 projectile material, corresponding to >2 x 10exp9 tons of mainly silica, iron, and magnesium in the K-Pg event bed. Detecting the "meteoritic" origin of these major elements, however, in a matrix of siliceous detritus, is practically impossible. Recent LA-ICP-MS analyses show that siliceous impact spherules - hydrated glass or altered to chlorite - in the Chicxulub event bed at various locations (e.g., Shell Creek, La Lajilla, La Popa) have REE patterns that are flat and un-fractionated, corresponding quite well to a typical CI-pattern. The REE abundances are chondritic to sub-chondritic. Mixing calculations indicate that the maximum REE contribution of UCC material to the REE budget of these spherules is on the order of 2 %, but usually much less. These

  11. Techniques for Surface-Temperature Measurements and Transition Detection on Projectiles at Hypersonic Velocities--Status Report No. 2

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.; Wilder, M. C.

    2006-01-01

    The latest developments in a research effort to advance techniques for measuring surface temperatures and heat fluxes and determining transition locations on projectiles in hypersonic free flight in a ballistic range are described. Spherical and hemispherical titanium projectiles were launched at muzzle velocities of 4.6-5.8 km/sec into air and nitrogen at pressures of 95-380 Torr. Hemisphere models with diameters of 2.22 cm had maximum pitch and yaw angles of 5.5-8 degrees and 4.7-7 degrees, depending on whether they were launched using an evacuated launch tube or not. Hemisphere models with diameters of 2.86 cm had maximum pitch and yaw angles of 2.0-2.5 degrees. Three intensified-charge-coupled-device (ICCD) cameras with wavelength sensitivity ranges of 480-870 nm (as well as one infrared camera with a wavelength sensitivity range of 3 to 5 microns), were used to obtain images of the projectiles in flight. Helium plumes were used to remove the radiating gas cap around the projectiles at the locations where ICCD camera images were taken. ICCD and infrared (IR) camera images of titanium hemisphere projectiles at velocities of 4.0-4.4 km/sec are presented as well as preliminary temperature data for these projectiles. Comparisons were made of normalized temperature data for shots at approx.190 Torr in air and nitrogen and with and without the launch tube evacuated. Shots into nitrogen had temperatures 6% lower than those into air. Evacuation of the launch tube was also found to lower the projectile temperatures by approx.6%.

  12. Impactor No More (Animation)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Quick Time Movie for PIA02130 Realtime Ejecta (Animation)

    This movie was taken by Deep Impact's flyby spacecraft shows the flash that occurred when comet Tempel 1 ran over the spacecraft's probe. It was taken by the flyby craft's medium-resolution camera.

  13. Compact ultradense matter impactors.

    PubMed

    Rafelski, Johann; Labun, Lance; Birrell, Jeremiah

    2013-03-15

    We study interactions of meteorlike compact ultradense objects (CUDO), having nuclear or greater density, with Earth and other rocky bodies in the Solar System as a possible source of information about novel forms of matter. We study the energy loss in CUDO puncture of the body and discuss differences between regular matter and CUDO impacts.

  14. ANNULAR IMPACTOR SAMPLING DEVICE

    DOEpatents

    Tait, G.W.C.

    1959-03-31

    A high-rate air sampler capable of sampling alphaemitting particles as small as 0.5 microns is described. The device is a cylindrical shaped cup that fits in front of a suction tube and which has sticky grease coating along its base. Suction forces contaminated air against the periodically monitored particle absorbing grease.

  15. Transient forces generated by projectiles on variable quality mouthguards monitored by instrumented impact testing

    PubMed Central

    Warnet, L; Greasley, A

    2001-01-01

    Objectives—(a) To determine the force-time trace that occurs when a spring mounted simulated upper jaw is impacted; (b) to examine if mouthguards of variable quality have significant influence on such force-time traces; (c) to attempt to relate physical events to the profile of the force-time traces recorded. Methods—A simulated jaw, consisting of ceramic teeth inserted into a hard rubber arch reinforced with a composite jawbone, was fitted with various mouthguards as part of a previous round robin study. A clinical assessment distinguished good, bad, and poor mouthguards, and these were each fitted to the jaw, which was then submitted to instrumental impact tests under conditions expected to produce tooth fractures. The force-time trace was recorded for such impact events. Results—The spring mounting method caused two distinct peaks in the force-time trace. The initial one was related to inertia effects and showed an increase in magnitude with impactor velocity as expected. The second peak showed features that were related to the differences in the mouthguards selected. Conclusions—The use of a force washer within a conical ended impactor enabled force-time traces to be recorded during the impact of a spring mounted simulated jaw fitted with mouthguards of variable quality. The spring mounting system causes an initial inertial peak followed by a second peak once the spring mount has fully compressed. Good fitting guards, which keep most teeth intact, result in high stiffness targets that in turn generate high reaction forces in the impactor. If the spring mounting is omitted, the two peaks are combined to give even higher reaction forces. The force-time trace offers some potential for assessing both overall mouthguard performance and individual events during the impact sequence. Mouthguards with good retention to the jaw remained attached during the impact event and helped to preserve the structural integrity of the target. This in turn developed high

  16. Reassessing the Aurignacian of Slovenia: techno-economic behaviour and direct dating of osseous projectile points.

    PubMed

    Moreau, Luc; Odar, Boštjan; Higham, Tom; Horvat, Aleksander; Pirkmajer, Darja; Turk, Peter

    2015-01-01

    The Palaeolithic of southern Central Europe has a long history of archaeological research. Particularly, the presence of numerous osseous projectile points in many early Upper Palaeolithic (EUP) assemblages in this region has attracted the attention of the international research community. However, the scarcity of properly identified and well-dated Aurignacian contexts represents an obstacle for investigation of the nature and timing of the Middle to Upper Palaeolithic transition. In this context, the question of whether Neandertals made Aurignacian osseous projectile points, either on their own or as a consequence of cultural interaction with anatomically modern humans (AMH), still remains an open issue. Here we reassess the EUP record of Slovenia by evaluating the Aurignacian character of the assemblages from Potočka zijalka, Mokriška jama and Divje babe I in the light of their suggested roots in the local Mousterian. We provide a comprehensive description of the lithic industry from Potočka zijalka, which represents one of the rare EUP assemblages of southern Central Europe with a representative number of lithic artefacts to be analysed from the perspective of lithic technology and raw material economy. Our re-analysis of the Slovenian assemblages is backed by a series of 11 new ultrafiltered collagen 14C dates obtained directly on associated osseous projectile points from the studied assemblages. The Aurignacian of Potočka zijalka underlines the remarkable consistency of the Early Aurignacian with low typo-technological variability across Europe, resulting from a marked dependence on transported toolkits and raw material conservation. The new radiocarbon determinations for the Aurignacian of Slovenia appear to post-date the 34-32 ka BP (thousands of years before present) threshold for the last Neandertals in the region. Although not falsified, the hypothesis of Aurignacian bone tools in southern Central Europe as a product of late Neandertals is not

  17. Performance of primary repair on colon injuries sustained from low-versus high-energy projectiles.

    PubMed

    Lazovic, Ranko; Radojevic, Nemanja; Curovic, Ivana

    2016-04-01

    Among various reasons, colon injuries may be caused by low- or high-energy firearm bullets, with the latter producing a temporary cavitation phenomenon. The available treatment options include primary repair and two-stage management, but recent studies have shown that primary repair can be widely used with a high success rate. This paper investigates the differences in performance of primary repair on these two types of colon injuries. Two groups of patients who sustained colon injuries due to single gunshot wounds, were retrospectively categorized based on the type of bullet. Primary colon repair was performed in all patients selected based on the inclusion and exclusion criteria (Stone and Fabian's criteria). An almost absolute homogeneity was attained among the groups in terms of age, latent time before surgery, and four trauma indexes. Only one patient from the low-energy firearm projectile group (4%) developed a postsurgical complication versus nine patients (25.8%) from the high-energy group, showing statistically significant difference (p = 0.03). These nine patients experienced the following postsurgical complications: pneumonia, abscess, fistula, suture leakage, and one multiorgan failure with sepsis. Previous studies concluded that one-stage primary repair is the best treatment option for colon injuries. However, terminal ballistics testing determined the projectile's path through the body and revealed that low-energy projectiles caused considerably lesser damage than their high-energy counterparts. Primary colon repair must be performed definitely for low-energy short firearm injuries but very carefully for high-energy injuries. Given these findings, we suggest that the treatment option should be determined based not only on the bullet type alone but also on other clinical findings. PMID:26874437

  18. Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

    NASA Astrophysics Data System (ADS)

    Thies, R.; Heinz, A.; Adachi, T.; Aksyutina, Y.; Alcantara-Núñes, J.; Altstadt, S.; Alvarez-Pol, H.; Ashwood, N.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Burgunder, G.; Camaño, M.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chakraborty, S.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Crespo, R.; Datta, U.; Díaz Fernández, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Freudenberger, M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Göbel, K.; Golubev, P.; Gonzalez Diaz, D.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Henriques, A.; Holl, M.; Ickert, G.; Ignatov, A.; Jakobsson, B.; Johansson, H. T.; Jonson, B.; Kalantar-Nayestanaki, N.; Kanungo, R.; Knöbel, R.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lepyoshkina, O.; Lindberg, S.; Machado, J.; Marganiec, J.; Maroussov, V.; Mostazo, M.; Movsesyan, A.; Najafi, A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietri, S.; Plag, R.; Prochazka, A.; Rahaman, A.; Rastrepina, G.; Reifarth, R.; Ribeiro, G.; Ricciardi, M. V.; Rigollet, C.; Riisager, K.; Röder, M.; Rossi, D.; Sanchez del Rio, J.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Stoica, V.; Streicher, B.; Taylor, J. T.; Tengblad, O.; Terashima, S.; Togano, Y.; Uberseder, E.; Van de Walle, J.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Wheldon, C.; Wilson, G.; Wimmer, C.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M. V.; Zilges, A.; Zuber, K.; R3B Collaboration

    2016-05-01

    Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from 10,12 -18C and B-1510 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1 p x n ) for relativistic 10,12 -18C and B-1510 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study.

  19. Unsteady Propagation Process of Oblique Detonation Waves Initiated by Hypersonic Spherical Projectiles

    NASA Astrophysics Data System (ADS)

    Maeda, Shinichi; Kasahara, Jiro; Matsuo, Akiko

    A spherical projectile was launched with 110% - 180% of a Chapman-Jouget (C-J) velocity into a detonable mixture, and we investigated the oblique detonation wave (ODW) that stabilized around it. High time-resolution visualizations were conducted using a high-speed camera with 1-μs frame speed to directly confirm the ODW stabilization and to investigate an unsteady phenomenon observed near the stabilizing criticality. In this case, the ODW was a three-dimensional conical wave, and the curvature effect on the conical detonation wave is not negligible near a projectile. We investigated the wave velocity distribution along the wave and revealed that it had a local minimum point at 0.8 - 0.9 times a C-J velocity during the decay process from an overdriven detonation near a projectile to a C-J ODW in the far field. We defined a characteristic wave curvature radius normalized by a cell size on this local minimum point. In this study, the minimum characteristic wave curvature radius of about 18 was needed to stabilize the conical detonation wave around a sphere. Near the stabilizing criticality, we also observed the unsteady ODW stabilization or detonation initiation on a shock-induced combustion. This unsteady regime was characterized by periodical onsets of local explosions that initiate or stabilize an ODW. We investigated the wave velocity distribution along this regime, and our findings revealed that the ODW transition or the detonation initiation following the shock-induced combustion occurred when the wave velocity decayed to 0.5 - 0.6 times a C-J velocity.

  20. Evidence from Polymict Ureilite Meteorites for a Single "Rubble-Pile" Ureilite Parent Asteroid Gardened by Several Distinct Impactors

    NASA Technical Reports Server (NTRS)

    Downes, Hilary; Mittlefehldt, David W.; Kita, Noriko T.; Valley, John W.

    2008-01-01

    Ureilites are ultramafic achondrite meteorites that have experienced igneous processing whilst retaining heterogeneity in mg# and oxygen isotope ratios. Polymict ureilites represent material derived from the surface of the ureilite parent asteroid(s). Electron microprobe analysis of more than 500 olivine and pyroxene clasts in six polymict ureilites reveals that they cover a statistically identical range of compositions to that shown by all known monomict ureilites. This is considered to be convincing evidence for derivation from a single parent asteroid. Many of the polymict ureilites also contain clasts that have identical compositions to the anomalously high Mn/Mg olivines and pyroxenes from the Hughes 009 monomict ureilite (here termed the Hughes cluster ). Four of the six samples also contain distinctive ferroan lithic clasts that have been derived from oxidized impactors. The presence of several common distinctive lithologies within the polymict ureilites is additional evidence that the ureilites were derived from a single parent asteroid. Olivine in a large lithic clast of augite-bearing ureilitic has an mg# of 97, extending the compositional range of known ureilite material. Our study confirms that ureilitic olivine clasts with mg#s < 85 are much more common than those with mg# > 85, which also show more variable Mn contents, including the melt-inclusion bearing "Hughes cluster" ureilites. We interpret this to indicate that the parent ureilite asteroid was disrupted by a major impact at a time when melt was still present in regions with a bulk mg# > 85, giving rise to the two types of ureilites: common ferroan ones that were already residual after melting and less common magnesian ones that were still partially molten when disruption occurred, some of which are the result of interaction of melts with residual mantle during disruption. A single daughter asteroid re-accreted from the disrupted remnants of the mantle of the proto-ureilite asteroid, giving rise