Computational Investigation of Effects of Grain Size on Ballistic Performance of Copper

Science.gov (United States)

He, Ge; Dou, Yangqing; Guo, Xiang; Liu, Yucheng

2018-01-01

Numerical simulations were conducted to compare ballistic performance and penetration mechanism of copper (Cu) with four representative grain sizes. Ballistic limit velocities for coarse-grained (CG) copper (grain size ≈ 90 µm), regular copper (grain size ≈ 30 µm), fine-grained (FG) copper (grain size ≈ 890 nm), and ultrafine-grained (UG) copper (grain size ≈ 200 nm) were determined for the first time through the simulations. It was found that the copper with reduced grain size would offer higher strength and better ductility, and therefore renders improved ballistic performance than the CG and regular copper. High speed impact and penetration behavior of the FG and UG copper was also compared with the CG coppers strengthened by nanotwinned (NT) regions. The comparison results showed the impact and penetration resistance of UG copper is comparable to the CG copper strengthened by NT regions with the minimum twin spacing. Therefore, besides the NT-strengthened copper, the single phase copper with nanoscale grain size could also be a strong candidate material for better ballistic protection. A computational modeling and simulation framework was proposed for this study, in which Johnson-Cook (JC) constitutive model is used to predict the plastic deformation of Cu; the JC damage model is to capture the penetration and fragmentation behavior of Cu; Bao-Wierzbicki (B-W) failure criterion defines the material's failure mechanisms; and temperature increase during this adiabatic penetration process is given by the Taylor-Quinney method.

Investigation on utilization of liquid propellant in ballistic range experiments

Energy Technology Data Exchange (ETDEWEB)

Saso, Akihiro; Oba, Shinji; Takayama, Kazuyoshi [Tohoku University, Sendai (Japan)

1999-10-31

Experiments were conducted in a ballistic range using a HAN (hydroxylammonium nitrate)-based liquid monopropellant, LP1846. In a 25-mm-bore single-stage gun, using bulk-loaded propellant of 10 to 35 g, a muzzle speed up to 1.0 km/s was obtained. Time variations of propellant chamber pressures and in-tube projectile velocity profiles were measured. The liquid propellant combustion was initiated accompanying a delay time which was created due to the pyrolysis of the propellant. In order to obtain reliable ballistic range performance, the method of propellant loading was revealed to be critical. Since the burning rate of the liquid propellant is relatively low, the peak acceleration and the muzzle speed strongly depend on the rupture pressure of a diaphragm that was inserted between the launch tube and the propellant chamber. (author)

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

Science.gov (United States)

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

2015-01-01

Modern ballistic helmets defeat penetrating bullets by energy transfer from the projectile to the helmet, producing helmet deformation. This deformation may cause severe injuries without completely perforating the helmet, termed "behind armor blunt trauma" (BABT). As helmets become lighter, the likelihood of larger helmet backface deformation under ballistic impact increases. To characterize the potential for BABT, seven postmortem human head/neck specimens wearing a ballistic protective helmet were exposed to nonperforating impact, using a 9 mm, full metal jacket, 124 grain bullet with velocities of 400-460 m/s. An increasing trend of injury severity was observed, ranging from simple linear fractures to combinations of linear and depressed fractures. Overall, the ability to identify skull fractures resulting from BABT can be used in forensic investigations. Our results demonstrate a high risk of skull fracture due to BABT and necessitate the prevention of BABT as a design factor in future generations of protective gear. © 2014 American Academy of Forensic Sciences.

Ballistic quality assurance

International Nuclear Information System (INIS)

Cassol, E.; Bonnet, J.; Porcheron, D.; Mazeron, J.J.; Peiffert, D.; Alapetite, C.

2012-01-01

This review describes the ballistic quality assurance for stereotactic intracranial irradiation treatments delivered with Gamma Knife R either dedicated or adapted medical linear accelerators. Specific and periodic controls should be performed in order to check the mechanical stability for both irradiation and collimation systems. If this step remains under the responsibility of the medical physicist, it should be done in agreement with the manufacturer's technical support. At this time, there are no recent published guidelines. With technological developments, both frequency and accuracy should be assessed in each institution according to the treatment mode: single versus hypo-fractionated dose, circular collimator versus micro-multi-leaf collimators. In addition, 'end-to-end' techniques are mandatory to find the origin of potential discrepancies and to estimate the global ballistic accuracy of the delivered treatment. Indeed, they include frames, non-invasive immobilization devices, localizers, multimodal imaging for delineation and in-room positioning imaging systems. The final precision that could be reasonably achieved is more or less 1 mm. (authors)

Ballistic parameters and trauma potential of pistol crossbows.

Science.gov (United States)

Frank, Matthias; Schikorr, Wolfgang; Tesch, Ralf; Werner, Ronald; Hanisch, Steffen; Peters, Dieter; Ekkernkamp, Axel; Bockholdt, Britta; Seifert, Julia

2013-07-01

Hand-held pistol crossbows, which are smaller versions of conventional crossbows, have recently increased in popularity. Similar to conventional crossbows, life threatening injuries due to bolts discharged from pistol crossbows are reported in forensic and traumatological literature. While the ballistic background of conventional crossbows is comprehensively investigated, there are no investigations on the characteristic ballistic parameters (draw force, potential energy, recurve factor, kinetic energy, and efficiency) of pistol crossbows. Two hand-held pistol crossbows (Barnett Commando and Mini Cross Bow, rated draw force 362.9 N or 80 lbs) were tested. The maximum draw force was investigated using a dynamic tensile testing machine (TIRAtest 2705, TIRA GmbH). The potential energy was determined graphically by polynomial regression as area under the force-draw curve. External ballistic parameters of the bolts discharged from pistol crossbows were measured using a redundant ballistic speed measurement system (Dual-BMC 21a and Dual-LS 1000, Werner Mehl Kurzzeitmesstechnik). The average maximum draw force was 190.3 and 175.6 N for the Barnett and Mini Cross Bow, respectively. The corresponding total energy expended was 10.7 and 11 J, respectively. The recurve factor was calculated to be 0.705 and 1.044, respectively. Average bolt velocity was measured 43 up to 52 m/s. The efficiency was calculated up to 0.94. To conclude, this work provides the pending ballistic data on this special subgroup of crossbows which operate on a remarkable low kinetic energy level. Furthermore, it demonstrates that the nominal draw force pretended in the sales brochure is grossly exaggerated.

The Truth About Ballistic Coefficients

OpenAIRE

Courtney, Michael; Courtney, Amy

2007-01-01

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

Is muscle coordination affected by loading condition in ballistic movements?

Science.gov (United States)

Giroux, Caroline; Guilhem, Gaël; Couturier, Antoine; Chollet, Didier; Rabita, Giuseppe

2015-02-01

This study aimed to investigate the effect of loading on lower limb muscle coordination involved during ballistic squat jumps. Twenty athletes performed ballistic squat jumps on a force platform. Vertical force, velocity, power and electromyographic (EMG) activity of lower limb muscles were recorded during the push-off phase and compared between seven loading conditions (0-60% of the concentric-only maximal repetition). The increase in external load increased vertical force (from 1962 N to 2559 N; P=0.0001), while movement velocity decreased (from 2.5 to 1.6 ms(-1); P=0.0001). EMG activity of tibialis anterior first peaked at 5% of the push-off phase, followed by gluteus maximus (35%), vastus lateralis and soleus (45%), rectus femoris (55%), gastrocnemius lateralis (65%) and semitendinosus (75%). This sequence of activation (P=0.67) and the amplitude of muscle activity (P=0.41) of each muscle were not affected by loading condition. However, a main effect of muscle was observed on these parameters (peak value: Ppush-off phase. Our findings suggest that muscle coordination is not influenced by external load during a ballistic squat jump. Copyright © 2014 Elsevier Ltd. All rights reserved.

Magnetic anisotropy and anisotropic ballistic conductance of thin magnetic wires

International Nuclear Information System (INIS)

Sabirianov, R.

2006-01-01

The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases. The spin moment of monatomic Fe wire may be as high as 3.4 μ B , while the orbital moment as high as 0.5 μ B . The magnetocrystalline anisotropy energy (MAE) was calculated for wires up to 0.6 nm in diameter starting from monatomic wire and adding consecutive shells for thicker wires. I observe that Fe wires exhibit the change sign with the stress applied along the wire. It means that easy axis may change from the direction along the wire to perpendicular to the wire. We find that ballistic conductance of the wire depends on the direction of the applied magnetic field, i.e. shows anisotropic ballistic magnetoresistance. This effect occurs due to the symmetry dependence of the splitting of degenerate bands in the applied field which changes the number of bands crossing the Fermi level. We find that the ballistic conductance changes with applied stress. Even for thicker wires the ballistic conductance changes by factor 2 on moderate tensile stain in our 5x4 model wire. Thus, the ballistic conductance of magnetic wires changes in the applied field due to the magnetostriction. This effect can be observed as large anisotropic BMR in the experiment

An integrated approach towards future ballistic neck protection materials selection.

Science.gov (United States)

Breeze, John; Helliker, Mark; Carr, Debra J

2013-05-01

Ballistic protection for the neck has historically taken the form of collars attached to the ballistic vest (removable or fixed), but other approaches, including the development of prototypes incorporating ballistic material into the collar of an under body armour shirt, are now being investigated. Current neck collars incorporate the same ballistic protective fabrics as the soft armour of the remaining vest, reflecting how ballistic protective performance alone has historically been perceived as the most important property for neck protection. However, the neck has fundamental differences from the thorax in terms of anatomical vulnerability, flexibility and equipment integration, necessitating a separate solution from the thorax in terms of optimal materials selection. An integrated approach towards the selection of the most appropriate combination of materials to be used for each of the two potential designs of future neck protection has been developed. This approach requires evaluation of the properties of each potential material in addition to ballistic performance alone, including flexibility, mass, wear resistance and thermal burden. The aim of this article is to provide readers with an overview of this integrated approach towards ballistic materials selection and an update of its current progress in the development of future ballistic neck protection.

Investigation on energy absorption efficiency of each layer in ballistic armour panel for applications in hybrid design

OpenAIRE

Yang, Yanfei; Chen, Xiaogang

2017-01-01

This study aims to reveal different energy absorption efficiency of each layer when armour panel is under ballistic impact. Through Finite Element (FE) modelling and ballistic tests, it is found that when fabrics are layered up in a panel, energy absorption efficiency is only 30%–60% of an individual fabric layer with free boundary condition. In addition, fabric layers in front, middle, and back exhibit different ballistic characteristics. Therefore, a new hybrid design principle has been pro...

Ballistic impact response of lipid membranes.

Science.gov (United States)

Zhang, Yao; Meng, Zhaoxu; Qin, Xin; Keten, Sinan

2018-03-08

Therapeutic agent loaded micro and nanoscale particles as high-velocity projectiles can penetrate cells and tissues, thereby serving as gene and drug delivery vehicles for direct and rapid internalization. Despite recent progress in developing micro/nanoscale ballistic tools, the underlying biophysics of how fast projectiles deform and penetrate cell membranes is still poorly understood. To understand the rate and size-dependent penetration processes, we present coarse-grained molecular dynamics simulations of the ballistic impact of spherical projectiles on lipid membranes. Our simulations reveal that upon impact, the projectile can pursue one of three distinct pathways. At low velocities below the critical penetration velocity, projectiles rebound off the surface. At intermediate velocities, penetration occurs after the projectile deforms the membrane into a tubular thread. At very high velocities, rapid penetration occurs through localized membrane deformation without tubulation. Membrane tension, projectile velocity and size govern which phenomenon occurs, owing to their positive correlation with the reaction force generated between the projectile and the membrane during impact. Two critical membrane tension values dictate the boundaries among the three pathways for a given system, due to the rate dependence of the stress generated in the membrane. Our findings provide broad physical insights into the ballistic impact response of soft viscous membranes and guide design strategies for drug delivery through lipid membranes using micro/nanoscale ballistic tools.

Ballistic current transport studies of ferromagnetic multilayer films and tunnel junctions (invited)

International Nuclear Information System (INIS)

Rippard, W. H.; Perrella, A. C.; Buhrman, R. A.

2001-01-01

Three applications of ballistic electron microscopy are used to study, with nanometer-scale resolution, the magnetic and electronic properties of magnetic multilayer thin films and tunnel junctions. First, the capabilities of ballistic electron magnetic microscopy are demonstrated through an investigation of the switching behavior of continuous Ni 80 Fe 20 /Cu/Co trilayer films in the presence of an applied magnetic field. Next, the ballistic, hot-electron transport properties of Co films and multilayers formed by thermal evaporation and magnetron sputtering are compared, a comparison which reveals significant differences in the ballistic transmissivity of thin film multilayers formed by the two techniques. Finally, the electronic properties of thin aluminum oxide tunnel junctions formed by thermal evaporation and sputter deposition are investigated. Here the ballistic electron microscopy studies yield a direct measurement of the barrier height of the aluminum oxide barriers, a result that is invariant over a wide range of oxidation conditions. [copyright] 2001 American Institute of Physics

Understanding the ballistic event : Methodology and observations relevant to ceramic armour

Science.gov (United States)

Healey, Adam

The only widely-accepted method of gauging the ballistic performance of a material is to carry out ballistic testing; due to the large volume of material required for a statistically robust test, this process is very expensive. Therefore a new test, or suite of tests, that employ widely-available and economically viable characterisation methods to screen candidate armour materials is highly desirable; in order to design such a test, more information on the armour/projectile interaction is required. This work presents the design process and results of using an adapted specimen configuration to increase the amount of information obtained from a ballistic test. By using a block of ballistic gel attached to the ceramic, the fragmentation generated during the ballistic event was captured and analysed. In parallel, quasi-static tests were carried out using ring-on-ring biaxial disc testing to investigate relationships between quasi-static and ballistic fragment fracture surfaces. Three contemporary ceramic armour materials were used to design the test and to act as a baseline; Sintox FA alumina, Hexoloy SA silicon carbide and 3M boron carbide. Attempts to analyse the post-test ballistic sample non-destructively using X-ray computed tomography (XCT) were unsuccessful due to the difference in the density of the materials and the compaction of fragments. However, the results of qualitative and quantitative fracture surface analysis using scanning electron microscopy showed similarities between the fracture surfaces of ballistic fragments at the edges of the tile and biaxial fragments; this suggests a relationship between quasi-static and ballistic fragments created away from the centre of impact, although additional research will be required to determine the reason for this. Ballistic event-induced porosity was observed and quantified on the fracture surfaces of silicon carbide samples, which decreased as distance from centre of impact increased; upon further analysis this

Is there ballistic transport in metallic nano-objects? Ballistic versus diffusive contributions

International Nuclear Information System (INIS)

Garcia, N; Bai Ming; Lu Yonghua; Munoz, M; Cheng Hao; Levanyuk, A P

2007-01-01

When discussing the resistance of an atomic-or nanometre-size contact we should consider both its ballistic and its diffusive contributions. But there is a contribution of the leads to the resistance of the contact as well. In this context, the geometry and the roughness of the surfaces limiting the system will contribute to the resistance, and these contributions should be added to the ideal ballistic resistance of the nanocontact. We have calculated, for metallic materials, the serial resistance of the leads arising from the roughness, and our calculations show that the ohmic resistance is as important as the ballistic resistance of the constriction. The classical resistance is a lower limit to the quantum resistance of the leads. Many examples of earlier experiments show that the mean free path of the transport electrons is of the order of the size of the contacts or the leads. This is not compatible with the idea of ballistic transport. This result may put in serious difficulties the current, existing interpretation of experimental data in metals where only small serial resistances compared with the ballistic component of the total resistance have been taken into account. The two-dimensional electron gas (2DEG) is also discussed and the serial corrections appear to be smaller than for metals. Experiments with these last systems are proposed that may reveal new interesting aspects in the physics of ballistic and diffusive transport

Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

Science.gov (United States)

Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

2014-01-01

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

Directory of Open Access Journals (Sweden)

Elias Randjbaran

2014-01-01

Full Text Available Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

Time-gated ballistic imaging using a large aperture switching beam.

Science.gov (United States)

Mathieu, Florian; Reddemann, Manuel A; Palmer, Johannes; Kneer, Reinhold

2014-03-24

Ballistic imaging commonly denotes the formation of line-of-sight shadowgraphs through turbid media by suppression of multiply scattered photons. The technique relies on a femtosecond laser acting as light source for the images and as switch for an optical Kerr gate that separates ballistic photons from multiply scattered ones. The achievable image resolution is one major limitation for the investigation of small objects. In this study, practical influences on the optical Kerr gate and image quality are discussed theoretically and experimentally applying a switching beam with large aperture (D = 19 mm). It is shown how switching pulse energy and synchronization of switching and imaging pulse in the Kerr cell influence the gate's transmission. Image quality of ballistic imaging and standard shadowgraphy is evaluated and compared, showing that the present ballistic imaging setup is advantageous for optical densities in the range of 8 ballistic imaging setup into a schlieren-type system with an optical schlieren edge.

Comparative study on sintered alumina for ballistic shielding application

International Nuclear Information System (INIS)

Melo, Francisco Cristovao Lourenco de; Goncalves, Diniz Pereira

1997-01-01

This work presents a development of the armor made from special ceramic materials and kevlar. An experimental investigation was conducted to study the ballistic penetration resistance on three samples taken from sintered alumina: a commercial one and two formulations A and B made in IAE/CTA. The main differences between the two formulations was the grain size and bend resistance. The knowledge of the mechanisms during the penetration and perforation process allowed to apply a ductile composite laminate made form kevlar under the alumina to delay its rupture. The last ballistic test showed how a Weibull's modulii and other mechanical properties are able to improve ballistic penetration resistance. (author)

Kinetics of diffusion-controlled and ballistically-controlled reactions

International Nuclear Information System (INIS)

Redner, S.

1995-01-01

The kinetics of diffusion-controlled two-species annihilation, A+B → O and single-species ballistically-controlled annihilation, A+A → O are investigated. For two-species annihilation, we describe the basic mechanism that leads to the formation of a coarsening mosaic of A- and B-domains. The implications of this picture on the distribution of reactants is discussed. For ballistic annihilation, dimensional analysis shows that the concentration and rms velocity decay as c∼t -α and v∼t -β , respectively, with α+β = 1 in any spatial dimension. Analysis of the Boltzmann equation for the evolution of the velocity distribution yields accurate predictions for the kinetics. New phenomena associated with discrete initial velocity distributions and with mixed ballistic and diffusive reactant motion are also discussed. (author)

Thermodynamic properties of UF sub 6 measured with a ballistic piston compressor

Science.gov (United States)

Sterritt, D. E.; Lalos, G. T.; Schneider, R. T.

1973-01-01

From experiments performed with a ballistic piston compressor, certain thermodynamic properties of uranium hexafluoride were investigated. Difficulties presented by the nonideal processes encountered in ballistic compressors are discussed and a computer code BCCC (Ballistic Compressor Computer Code) is developed to analyze the experimental data. The BCCC unfolds the thermodynamic properties of uranium hexafluoride from the helium-uranium hexafluoride mixture used as the test gas in the ballistic compressor. The thermodynamic properties deduced include the specific heat at constant volume, the ratio of specific heats for UF6, and the viscous coupling constant of helium-uranium hexafluoride mixtures.

Ballistic Jumping Drops on Superhydrophobic Surfaces via Electrostatic Manipulation.

Science.gov (United States)

Li, Ning; Wu, Lei; Yu, Cunlong; Dai, Haoyu; Wang, Ting; Dong, Zhichao; Jiang, Lei

2018-02-01

The ballistic ejection of liquid drops by electrostatic manipulating has both fundamental and practical implications, from raindrops in thunderclouds to self-cleaning, anti-icing, condensation, and heat transfer enhancements. In this paper, the ballistic jumping behavior of liquid drops from a superhydrophobic surface is investigated. Powered by the repulsion of the same kind of charges, water drops can jump from the surface. The electrostatic acting time for the jumping of a microliter supercooled drop only takes several milliseconds, even shorter than the time for icing. In addition, one can control the ballistic jumping direction precisely by the relative position above the electrostatic field. The approach offers a facile method that can be used to manipulate the ballistic drop jumping via an electrostatic field, opening the possibility of energy efficient drop detaching techniques in various applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Penetration resistance and ballistic-impact behavior of Ti/TiAl3 metal/intermetallic laminated composites (MILCs: A computational investigation

Directory of Open Access Journals (Sweden)

Jennifer S. Snipes

2016-06-01

Full Text Available A comprehensive computational engineering analysis is carried out in order to assess suitability of the Ti/TiAl3 metal/intermetallic laminated composites (MILCs for use in both structural and add-on armor applications. This class of composite materials consists of alternating sub-millimeter thick layers of Ti (the ductile and tough constituent and TiAl3 (the stiff and hard constituent. In recent years, this class of materials has been investigated for potential use in light-armor applications as a replacement for the traditional metallic or polymer-matrix composite materials. Within the computational analysis, an account is given to differing functional requirements for candidate materials when used in structural and add-on ballistic armor. The analysis employed is of a transient, nonlinear-dynamics, finite-element character, and the problem investigated involves normal impact (i.e. under zero obliquity angle of a Ti/TiAl3 MILC target plate, over a range of incident velocities, by a fragment simulating projectile (FSP. This type of analysis can provide more direct information regarding the ballistic limit of the subject armor material, as well as help with the identification of the nature and the efficacy of various FSP material-deformation/erosion and kinetic-energy absorption/dissipation phenomena and processes. The results obtained clearly revealed that Ti/TiAl3 MILCs are more suitable for use in add-on ballistic, than in structural armor applications.

Terminal Ballistics

CERN Document Server

Rosenberg, Zvi

2012-01-01

This book covers the important issues of terminal ballistics in a comprehensive way combining experimental data, numerical simulations and analytical modeling. The first chapter reviews the experimental equipment which are used for ballistic tests and the diagnostics for material characterization under impulsive loading conditions. The second chapter covers essential features of the codes which are used for terminal ballistics such as the Euler vs. Lagrange schemes and meshing techniques, as well as the most popular material models. The third chapter, devoted to the penetration mechanics of rigid penetrators, brings the update of modeling in this field. The fourth chapter deals with plate perforation and the fifth chapter deals with the penetration mechanics of shaped charge jets and eroding long rods. The last two chapters discuss several techniques for the disruption and defeating of the main threats in armor design. Throughout the book the authors demonstrate the advantages of numerical simulations in unde...

Investigation of energy levels of Er-impurity centers in Si by the method of ballistic electron emission spectroscopy

International Nuclear Information System (INIS)

Filatov, D. O.; Zimovets, I. A.; Isakov, M. A.; Kuznetsov, V. P.; Kornaukhov, A. V.

2011-01-01

The method of ballistic electron emission spectroscopy is used for the first time to study the energy spectrum of Er-impurity complexes in Si. The features are observed in the ballistic electron spectra of mesa diodes based on p + -n + Si structures with a thin (∼30 nm) p + -Si:Er surface layer in the region of ballistic-electron energies eV t lower than the conduction-band-edge energy E c in this layer. They are associated with the tunnel injection of ballistic electrons from the probe of the scanning tunnel microscope to the deep donor levels of the Er-impurity complexes in the p + -Si:Er layer with subsequent thermal excitation into the conduction band and the diffusion to the p + -n + junction and the direct tunneling in it. To verify this assumption, the ballistic-electron transport was simulated in the system of the Pt probe, native-oxide layer SiO 2 -p + -Si:Er-n + , and Si substrate. By approximating the experimental ballistic-electron spectra with the modeling spectra, the ground-state energy of the Er complex in Si was determined: E d ≈ E c − 0.27 eV. The indicated value is consistent with the data published previously and obtained from the measurements of the temperature dependence of the free-carrier concentration in Si:Er layers.

Effects of Different Relative Loads on Power Performance During the Ballistic Push-up.

Science.gov (United States)

Wang, Ran; Hoffman, Jay R; Sadres, Eliahu; Bartolomei, Sandro; Muddle, Tyler W D; Fukuda, David H; Stout, Jeffrey R

2017-12-01

Wang, R, Hoffman, JR, Sadres, E, Bartolomei, S, Muddle, TWD, Fukuda, DH, and Stout, JR. Effects of different relative loads on power performance during the ballistic push-up. J Strength Cond Res 31(12): 3411-3416, 2017-The purpose of this investigation was to examine the effect of load on force and power performance during a ballistic push-up. Sixty (24.5 ± 4.3 years, 1.75 ± 0.07 m, and 80.8 ± 13.5 kg) recreationally active men who participated in this investigation completed all testing and were included in the data analysis. All participants were required to perform a 1 repetition maximum bench press, and ballistic push-ups without external load (T1), with 10% (T2) and 20% (T3) of their body mass. Ballistic push-ups during T2 and T3 were performed using a weight loaded vest. Peak and mean force, power, as well as net impulse and flight time were determined for each ballistic push-up. Peak and mean force were both significantly greater (p ballistic push-up, regardless of the participants' level of strength.

Ballistic representation for kinematic access

Science.gov (United States)

Alfano, Salvatore

2011-01-01

This work uses simple two-body orbital dynamics to initially determine the kinematic access for a ballistic vehicle. Primarily this analysis was developed to assess when a rocket body might conjunct with an orbiting satellite platform. A family of access opportunities can be represented as a volume for a specific rocket relative to its launch platform. Alternately, the opportunities can be represented as a geographical footprint relative to aircraft or satellite position that encompasses all possible launcher locations for a specific rocket. A thrusting rocket is treated as a ballistic vehicle that receives all its energy at launch and follows a coasting trajectory. To do so, the rocket's burnout energy is used to find its equivalent initial velocity for a given launcher's altitude. Three kinematic access solutions are then found that account for spherical Earth rotation. One solution finds the maximum range for an ascent-only trajectory while another solution accommodates a descending trajectory. In addition, the ascent engagement for the descending trajectory is used to depict a rapid access scenario. These preliminary solutions are formulated to address ground-, sea-, or air-launched vehicles.

Non linear interaction between a Langmuir wave and a ballistic perturbation

International Nuclear Information System (INIS)

Gervais, F.; Olivain, J.; Quemeneur, A.; Trocheris, M.

1979-05-01

The theoretical solutions of the Landau-Vlasov initial value problem giving mode-mode coupling usually neglect the free-streaming contribution. We solve theoretically this problem including the ballistic terms. We find that a new mode appears resulting from the nonlinear interaction between the Landau component and the ballistic perturbation. The amplitude of this mode is calculated as a function of distance and compared with experimental results in a plasma column

Mechanism of ballistic collisions

International Nuclear Information System (INIS)

Sindoni, J.M.; Sharma, R.D.

1992-01-01

Ballistic collisions is a term used to describe atom-diatom collisions during which a substantial fraction of the initial relative translational energy is converted into the internal energy of the diatom. An exact formulation of the impulse approach to atom-diatom collisions is shown to be in excellent agreement with the experimental results for the CsF-Ar system at 1.1 eV relative translational energy for laboratory scattering angles of 30 degree and 60 degree. The differential cross section for scattering of CsF peaks at two distinct recoil velocities. The peak centered at the recoil velocity corresponding to elastic scattering has been called the elastic peak. This peak is shown to consist of several hundred inelastic transitions, most involving a small change in internal energy. The peak near the center-of-mass (c.m.) velocity is called the ballistic peak and is shown to consist of highly inelastic (ballistic) transitions. It is shown that transitions comprising the ballistic (elastic) peak occur when an Ar atom strikes the F (Cs) end of CsF. When one is looking along the direction of the c.m. velocity, the signal from a single transition, which converts about 99.99% of the relative translational energy into internal energy, may be larger than the signal from any other ballistic transition by as much as an order of magnitude. This property may be used to prepare state-selected and velocity-selected beams for further studies. It is also pointed out that the ballistic peak may be observed for any atom-molecule system under appropriate circumstances

Experimental evaluation of ballistic hazards in imaging diagnostic center.

Science.gov (United States)

Karpowicz, Jolanta; Gryz, Krzysztof

2013-04-01

Serious hazards for human health and life and devices in close proximity to the magnetic resonance scanners (MRI scanners) include the effects of being hit by ferromagnetic objects attracted by static magnetic field (SMF) produced by scanner magnet - the so-called ballistic hazards classified among indirect electromagnetic hazards. International safety guidelines and technical literature specify different SMF threshold values regarding ballistic hazards - e.g. 3 mT (directive 2004/40/EC, EN 60601-2-33), and 30 mT (BMAS 2009, directive proposal 2011). Investigations presented in this article were performed in order to experimentally verify SMF threshold for ballistic hazards near MRI scanners used in Poland. Investigations were performed with the use of a laboratory source of SMF (0-30 mT) and MRI scanners of various types. The levels of SMF in which metal objects of various shapes and 0.4-500 g mass are moved by the field influence were investigated. The distance from the MRI scanners (0.2-3T) where hazards may occur were also investigated. Objects investigated under laboratory conditions were moved by SMF of 2.2-15 mT magnetic flux density when they were freely suspended, but were moved by the SMF of 5.6-22 mT when they were placed on a smooth surface. Investigated objects were moved in fields of 3.5-40 mT by MRI scanners. Distances from scanner magnet cover, where ballistic hazards might occur are: up to 0.5 m for 0.2-0.3T scanners; up to 1.3 m for 0.5T scanners; up to 2.0 m for 1.5T scanners and up to 2.5 m for 3T scanners (at the front and back of the magnet). It was shown that SMF of 3 mT magnetic flux density should be taken as the threshold for ballistic hazards. Such level is compatible with SMF limit value regarding occupational safety and health-protected areas/zones, where according to the Polish labor law the procedures of work environment inspection and prevention measures regarding indirect electromagnetic hazards should be applied. Presented results

Conformable Self-Healing Ballistic Armor

Science.gov (United States)

2011-06-28

public release, distribution unlimited 13. SUPPLEMENTARY NOTES Patent No: US 7,966,923 B2 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION...B2 5 Each unit of shell 10 of the ballistic annor of the subject invention further comprises fastening means 20 to attach each such shell IOta the...selectively affixing the conformable ballistic annor to the vehicle is a secure manner, both on a temporal)’ orpennanent basis. The ballistic

A Histological Analysis of Visceral Organs to Evaluate the Effect of Duration of Heating From Refrigeration to Core Body Temperature for Ballistics Investigations.

Science.gov (United States)

Humphrey, Caitlin; Kumaratilake, Jaliya

2017-12-01

Animal organs have been used in ballistics research to investigate the effects on human organs. Such organs are refrigerated until the investigation to minimize autolytic degradation and at times have been reheated to the human core body temperature to simulate the in situ environment. The aim of this investigation was to study the microstructural changes that may occur in fresh chilled visceral organs of the thorax and abdomen (ie, heart, lung, liver, and kidney) during the period of reheating to 37°C. Fifty-millimeter cubes of porcine heart, lung, liver, and kidney were taken rapidly after slaughter, chilled overnight, and the next morning were reheated to core body temperature (37°C). Histological changes occurring in the tissues during the reheating phase were investigated. The findings indicated that no cytoplasmic or nuclear changes occurred in any of the tissues during the period of reheating. Therefore, reheating of animal organs to the human core body temperature is not necessary, if the organs are refrigerated.

Management of civilian ballistic fractures.

Science.gov (United States)

Seng, V S; Masquelet, A C

2013-12-01

The management of ballistic fractures, which are open fractures, has often been studied in wartime and has benefited from the principles of military surgery with debridement and lavage, and the use of external fixation for bone stabilization. In civilian practice, bone stabilization of these fractures is different and is not performed by external fixation. Fifteen civilian ballistic fractures, Gustilo II or IIIa, two associated with nerve damage and none with vascular damage, were reviewed. After debridement and lavage, ten internal fixations and five conservative treatments were used. No superficial or deep surgical site infection was noted. Fourteen of the 15 fractures (93%) healed without reoperation. Eleven of the 15 patients (73%) regained normal function. Ballistic fractures have a bad reputation due to their many complications, including infections. In civilian practice, the use of internal fixation is not responsible for excessive morbidity, provided debridement and lavage are performed. Civilian ballistic fractures, when they are caused by low-velocity firearms, differ from military ballistic fractures. Although the principle of surgical debridement and lavage remains the same, bone stabilization is different and is similar to conventional open fractures. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Experimental evaluation of ballistic hazards in imaging diagnostic center

International Nuclear Information System (INIS)

Karpowicz, Jolanta; Gryz, Krzysztof

2013-01-01

Serious hazards for human health and life and devices in close proximity to the magnetic resonance scanners (MRI scanners) include the effects of being hit by ferromagnetic objects attracted by static magnetic field (SMF) produced by scanner magnet – the so-called ballistic hazards classified among indirect electromagnetic hazards. International safety guidelines and technical literature specify different SMF threshold values regarding ballistic hazards – e.g. 3 mT (directive 2004/40/EC, EN 60601-2-33), and 30 mT (BMAS 2009, directive proposal 2011). Investigations presented in this article were performed in order to experimentally verify SMF threshold for ballistic hazards near MRI scanners used in Poland. Investigations were performed with the use of a laboratory source of SMF (0–30 mT) and MRI scanners of various types. The levels of SMF in which metal objects of various shapes and 0.4–500 g mass are moved by the field influence were investigated. The distance from the MRI scanners (0.2–3T) where hazards may occur were also investigated. Objects investigated under laboratory conditions were moved by SMF of 2.2–15 mT magnetic flux density when they were freely suspended, but were moved by the SMF of 5.6–22 mT when they were placed on a smooth surface. Investigated objects were moved in fields of 3.5–40 mT by MRI scanners. Distances from scanner magnet cover, where ballistic hazards might occur are: up to 0.5 m for 0.2–0.3T scanners; up to 1.3 m for 0.5T scanners; up to 2.0 m for 1.5T scanners and up to 2.5 m for 3T scanners (at the front and back of the magnet). It was shown that SMF of 3 mT magnetic flux density should be taken as the threshold for ballistic hazards. Such level is compatible with SMF limit value regarding occupational safety and health-protected areas/zones, where according to the Polish labor law the procedures of work environment inspection and prevention measures regarding indirect electromagnetic hazards should be applied

Ballistic protection performance of curved armor systems with or without debondings/delaminations

International Nuclear Information System (INIS)

Tan, Ping

2014-01-01

Highlights: • Influence of pre-existing defect in an armor system on its ballistic performance. • Development of finite element models for the ballistic performance of armor systems. • Prediction of the ballistic limit and back face deformation of curved armor systems. - Abstract: In order to discern how pre-existing defects such as single or multiple debondings/delaminations in a curved armor system may affect its ballistic protection performance, two-dimensional axial finite element models were generated using the commercial software ANSYS/Autodyn. The armor systems considered in this investigation are composed of boron carbide front component and Kevlar/epoxy backing component. They are assumed to be perfectly bonded at the interface without defects. The parametric study shows that for the cases considered, the maximum back face deformation of a curved armor system with or without defects is more sensitive to its curvature, material properties of the ceramic front component, and pre-existing defect size and location than the ballistic limit velocity. Additionally, both the ballistic limit velocity and maximum back face deformation are significantly affected by the backing component thickness, front/backing component thickness ratio and the number of delaminations

Ballistic properties of bidirectional fiber/resin composites

OpenAIRE

Dimeski, Dimko; Spaseska, Dijana

2004-01-01

The aim of the research was to make evaulation of the ballistic strenth of four different composites intended to be used in manufacturing of ballistic items for personal protection. Research has been performed on glass, ntlon, HPPE and aramide fibers...... Key words. aramid, ballistic, V50

Ballistic electron transport in mesoscopic samples

International Nuclear Information System (INIS)

Diaconescu, D.

2000-01-01

In the framework of this thesis, the electron transport in the ballistic regime has been studied. Ballistic means that the lateral sample dimensions are smaller than the mean free path of the electrons, i.e. the electrons can travel through the whole device without being scattered. This leads to transport characteristics that differ significantly from the diffusive regime which is realised in most experiments. Making use of samples with high mean free path, features of ballistic transport have been observed on samples with sizes up to 100 μm. The basic device used in ballistic electron transport is the point contact, from which a collimated beam of ballistic electrons can be injected. Such point contacts were realised with focused ion beam (FIB) implantation and the collimating properties were analysed using a two opposite point contact configuration. The typical angular width at half maximum is around 50 , which is comparable with that of point contacts defined by other methods. (orig.)

Dense-plasma research using ballistic compressors

International Nuclear Information System (INIS)

Hess, H.

1986-01-01

An introduction is given to research on dense (or nonideal) plasmas which can be generated to advantage by ballistic compressors. Some properties of ballistic compressors are discussed especially in comparison with shock tubes. A short review is given on the history of these devices for high-pressure plasma generation. The present state of the art is reported including research on the two ZIE (Central Institute for Electron Physics) ballistic compressors. (author)

Development of ballistics identification—from image comparison to topography measurement in surface metrology

International Nuclear Information System (INIS)

Song, J; Chu, W; Vorburger, T V; Thompson, R; Renegar, T B; Zheng, A; Yen, J; Silver, R; Ols, M

2012-01-01

Fired bullets and ejected cartridge cases have unique ballistics signatures left by the firearm. By analyzing the ballistics signatures, forensic examiners can trace these bullets and cartridge cases to the firearm used in a crime scene. Current automated ballistics identification systems are primarily based on image comparisons using optical microscopy. The correlation accuracy depends on image quality which is largely affected by lighting conditions. Because ballistics signatures are geometrical micro-topographies by nature, direct measurement and correlation of the surface topography is being investigated for ballistics identification. A Two-dimensional and Three-dimensional Topography Measurement and Correlation System was developed at the National Institute of Standards and Technology for certification of Standard Reference Material 2460/2461 bullets and cartridge cases. Based on this system, a prototype system for bullet signature measurement and correlation has been developed for bullet signature identifications, and has demonstrated superior correlation results. (paper)

Ballistic transport and electronic structure

NARCIS (Netherlands)

Schep, Kees M.; Kelly, Paul J.; Bauer, Gerrit E.W.

1998-01-01

The role of the electronic structure in determining the transport properties of ballistic point contacts is studied. The conductance in the ballistic regime is related to simple geometrical projections of the Fermi surface. The essential physics is first clarified for simple models. For real

Ballistic propagation of turbulence front in tokamak edge plasmas

International Nuclear Information System (INIS)

Sugita, Satoru; Itoh, Kimitaka; Itoh, Sanae-I; Yagi, Masatoshi; Fuhr, Guillaume; Beyer, Peter; Benkadda, Sadruddin

2012-01-01

The flux-driven nonlinear simulation of resistive ballooning mode turbulence with tokamak edge geometry is performed to study the non-steady component in the edge turbulence. The large-scale and dynamical events in transport are investigated in a situation where the mean flow is suppressed. Two types of dynamics are observed. One is the radial propagation of the pulse of pressure gradient, the other is the appearance/disappearance of radially elongated global structure of turbulent heat flux. The ballistic propagation is observed in the pulse of pressure gradient, which is associated with the front of turbulent heat flux. We focus on this ballistic propagation phenomenon. Both of the bump of pressure gradient and the front of heat flux propagate inward and outward direction. It is confirmed that the strong fluctuation propagates with the pulse front. It is observed that the number of pulses going outward is close to those going inward. This ballistic phenomenon does not contradict to the turbulence spreading theory. Statistical characteristics of the ballistic propagation of pulses are evaluated and compared with scaling laws which is given by the turbulence spreading theory. It is found that they give qualitatively good agreement. (paper)

Ship Anti Ballistic Missile Response (SABR)

OpenAIRE

Johnson, Allen P.; Breeden, Bryan; Duff, Willard Earl; Fishcer, Paul F.; Hornback, Nathan; Leiker, David C.; Carlisle, Parker; Diersing, Michael; Devlin, Ryan; Glenn, Christopher; Hoffmeister, Chris; Chong, Tay Boon; Sing, Phang Nyit; Meng, Low Wee; Meng, Fann Chee

2006-01-01

Includes supplementary material. Based on public law and Presidential mandate, ballistic missile defense development is a front-burner issue for homeland defense and the defense of U.S. and coalition forces abroad. Spearheaded by the Missile Defense Agency, an integrated ballistic missile defense system was initiated to create a layered defense composed of land-, air-, sea-, and space-based assets. The Ship Anti-Ballistic Response (SABR) Project is a systems engineering approach t...

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

Directory of Open Access Journals (Sweden)

Hong Yu

2009-04-01

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

Molecular Dynamics Studies on Ballistic Thermal Resistance of Graphene Nano-Junctions

International Nuclear Information System (INIS)

Yao Wen-Jun; Cao Bing-Yang

2015-01-01

Ballistic thermal resistance of graphene nano-junctions is investigated using non-equilibrium molecular dynamics simulation. The simulation system is consisted of two symmetrical trapezoidal or rectangular graphene nano-ribbons (GNRs) and a connecting nanoscale constriction in between. From the simulated temperature profile, a big temperature jump resulted from the constriction is found, which is proportional to the heat current and corresponds to a local ballistic thermal resistance. Fixing the constriction width and the length of GNRs, this ballistic thermal resistance is independent of the width of the GNRs bottom layer, i.e., the convex angle. But interestingly, this thermal resistance has obvious size effect. It is inversely proportional to the constriction width and will disappear with the constriction being wider. Moreover, based on the phonon dynamics theory, a theoretical model of the ballistic thermal resistance in two-dimensional nano-systems is developed, which gives a good explanation on microcosmic level and agrees well with the simulation result quantitatively and qualitatively. (paper)

Effect of ballistic electrons on ultrafast thermomechanical responses of a thin metal film

International Nuclear Information System (INIS)

Xiong Qi-lin; Tian Xin

2017-01-01

The ultrafast thermomechanical coupling problem in a thin gold film irradiated by ultrashort laser pulses with different electron ballistic depths is investigated via the ultrafast thermoelasticity model. The solution of the problem is obtained by solving finite element governing equations. The comparison between the results of ultrafast thermomechanical coupling responses with different electron ballistic depths is made to show the ballistic electron effect. It is found that the ballistic electrons have a significant influence on the ultrafast thermomechanical coupling behaviors of the gold thin film and the best laser micromachining results can be achieved by choosing the specific laser technology (large or small ballistic range). In addition, the influence of simplification of the ultrashort laser pulse source on the results is studied, and it is found that the simplification has a great influence on the thermomechanical responses, which implies that care should be taken when the simplified form of the laser source term is applied as the Gaussian heat source. (paper)

Ballistic phonon transport in holey silicon.

Science.gov (United States)

Lee, Jaeho; Lim, Jongwoo; Yang, Peidong

2015-05-13

When the size of semiconductors is smaller than the phonon mean free path, phonons can carry heat with no internal scattering. Ballistic phonon transport has received attention for both theoretical and practical aspects because Fourier's law of heat conduction breaks down and the heat dissipation in nanoscale transistors becomes unpredictable in the ballistic regime. While recent experiments demonstrate room-temperature evidence of ballistic phonon transport in various nanomaterials, the thermal conductivity data for silicon in the length scale of 10-100 nm is still not available due to experimental challenges. Here we show ballistic phonon transport prevails in the cross-plane direction of holey silicon from 35 to 200 nm. The thermal conductivity scales linearly with the length (thickness) even though the lateral dimension (neck) is as narrow as 20 nm. We assess the impact of long-wavelength phonons and predict a transition from ballistic to diffusive regime using scaling models. Our results support strong persistence of long-wavelength phonons in nanostructures and are useful for controlling phonon transport for thermoelectrics and potential phononic applications.

Ballistic Graphene Josephson Junctions from the Short to the Long Junction Regimes.

Science.gov (United States)

Borzenets, I V; Amet, F; Ke, C T; Draelos, A W; Wei, M T; Seredinski, A; Watanabe, K; Taniguchi, T; Bomze, Y; Yamamoto, M; Tarucha, S; Finkelstein, G

2016-12-02

We investigate the critical current I_{C} of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, I_{C} is found to scale as ∝exp(-k_{B}T/δE). The extracted energies δE are independent of the carrier density and proportional to the level spacing of the ballistic cavity. As T→0 the critical current of a long (or short) junction saturates at a level determined by the product of δE (or Δ) and the number of the junction's transversal modes.

Drag of ballistic electrons by an ion beam

Energy Technology Data Exchange (ETDEWEB)

Gurevich, V. L.; Muradov, M. I., E-mail: mag.muradov@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2015-12-15

Drag of electrons of a one-dimensional ballistic nanowire by a nearby one-dimensional beam of ions is considered. We assume that the ion beam is represented by an ensemble of heavy ions of the same velocity V. The ratio of the drag current to the primary current carried by the ion beam is calculated. The drag current turns out to be a nonmonotonic function of velocity V. It has a sharp maximum for V near v{sub nF}/2, where n is the number of the uppermost electron miniband (channel) taking part in conduction and v{sub nF} is the corresponding Fermi velocity. This means that the phenomenon of ion beam drag can be used for investigation of the electron spectra of ballistic nanostructures. We note that whereas observation of the Coulomb drag between two parallel quantum wires may in general be complicated by phenomena such as tunneling and phonon drag, the Coulomb drag of electrons of a one-dimensional ballistic nanowire by an ion beam is free of such spurious effects.

Nonlocal nature of the resistance in classical ballistic transport

International Nuclear Information System (INIS)

Sukhorukov, E.V.; Levinson, I.B.

1990-01-01

An investigation is made of the resistance of ballistic microstructures formed in the two-dimensional electron gas of a GaAs/AlGaAs heterojunction representing combinations of long channels. It is shown that the nonlocal nature of the resistance (dependence on the measurement method) is unrelated to the quantum nature of the electron behavior, but is solely due to the ballistic nature of microstructures and does not disappear in the classical limit. An analog of the Landauer equation is obtained for the resistance measured by the four-probe method allowing for the geometry of the measuring probes

Investigation of dental alginate and agar impression materials as a brain simulant for ballistic testing.

Science.gov (United States)

Falland-Cheung, Lisa; Piccione, Neil; Zhao, Tianqi; Lazarjan, Milad Soltanipour; Hanlin, Suzanne; Jermy, Mark; Waddell, J Neil

2016-06-01

Routine forensic research into in vitro skin/skull/brain ballistic blood backspatter behavior has traditionally used gelatin at a 1:10 Water:Powder (W:P) ratio by volume as a brain simulant. A limitation of gelatin is its high elasticity compared to brain tissue. Therefore this study investigated the use of dental alginate and agar impression materials as a brain simulant for ballistic testing. Fresh deer brain, alginate (W:P ratio 91.5:8.5) and agar (W:P ratio 81:19) specimens (n=10) (11×22×33mm) were placed in transparent Perspex boxes of the same internal dimensions prior to shooting with a 0.22inch caliber high velocity air gun. Quantitative analysis to establish kinetic energy loss, vertical displacement elastic behavior and qualitative analysis to establish elasticity behavior was done via high-speed camera footage (SA5, Photron, Japan) using Photron Fastcam Viewer software (Version 3.5.1, Photron, Japan) and visual observation. Damage mechanisms and behavior were qualitatively established by observation of the materials during and after shooting. The qualitative analysis found that of the two simulant materials tested, agar behaved more like brain in terms of damage and showed similar mechanical response to brain during the passage of the projectile, in terms of energy absorption and vertical velocity displacement. In conclusion agar showed a mechanical and subsequent damage response that was similar to brain compared to alginate. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions

International Nuclear Information System (INIS)

Bock, Claudia; Weingart, Sonja; Karaissaridis, Epaminondas; Kunze, Ulrich; Speck, Florian; Seyller, Thomas

2012-01-01

In this paper we investigate the influence of material and device properties on the ballistic transport in epitaxial monolayer graphene and epitaxial quasi-free-standing monolayer graphene. Our studies comprise (a) magneto-transport in two-dimensional (2D) Hall bars, (b) temperature- and magnetic-field-dependent bend resistance of unaligned and step-edge-aligned orthogonal cross junctions, and (c) the influence of the lead width of the cross junctions on ballistic transport. We found that ballistic transport is highly sensitive to scattering at the step edges of the silicon carbide substrate. A suppression of the ballistic transport is observed if the lead width of the cross junction is reduced from 50 nm to 30 nm. In a 50 nm wide device prepared on quasi-free-standing graphene we observe a gradual transition from the ballistic into the diffusive transport regime if the temperature is increased from 4.2 to about 50 K, although 2D Hall bars show a temperature-independent mobility. Thus, in 1D devices additional temperature-dependent scattering mechanisms play a pivotal role. (paper)

Supra-ballistic phonons

International Nuclear Information System (INIS)

Russell, F.M.

1989-05-01

Energetic particles moving with a solid, either from nuclear reactions or externally injected, deposit energy by inelastic scattering processes which eventually appears as thermal energy. If the transfer of energy occurs in a crystalline solid then it is possible to couple some of the energy directly to the nuclei forming the lattice by generating phonons. In this paper the transfer of energy from a compound excited nucleus to the lattice is examined by introducing a virtual particle Π. It is shown that by including a Π in the nuclear reaction a substantial amount of energy can be coupled directly to the lattice. In the lattice this particle behaves as a spatially localized phonon of high energy, the so-called supra-ballistic phonon. By multiple inelastic scattering the supra-ballistic phonon eventually thermalizes. Because both the virtual particle Π and the equivalent supra-ballistic phonon have no charge or spin and can only exist within a lattice it is difficult to detect other than by its decay into thermal phonons. The possibility of a Π removing excess energy from a compound nucleus formed by the cold fusion of deuterium is examined. (Author)

The Cooperative Ballistic Missile Defence Game

NARCIS (Netherlands)

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

2013-01-01

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

On the influence of particle morphology on the post-impact ballistic response of ceramic armour materials

Science.gov (United States)

Hameed, Amer; Appleby-Thomas, Gareth; Wood, David; Jaansalu, Kevin

2015-06-01

Recent studies have shown evidence that the ballistic-resistance of fragmented (comminuted) ceramics is independent of the original strength of the material. In particular, experimental investigations into the ballistic behaviour of such fragmented ceramics have indicated that this response is correlated to shattered ceramic morphology. This suggests that careful control of ceramic microstructure - and therefore failure paths - might provide a route to optimise post-impact ballistic performance, thereby enhancing multi-hit capability. In this study, building on previous in-house work, ballistic tests were conducted using pre-formed `fragmented-ceramic' analogues based around three morphologically differing (but chemically identical) alumina feedstock materials compacted into target `pucks. In an evolution of previous work, variation of target thickness provided additional insight into an apparent morphology-based contribution to ballistic response.

Dynamic Load Measurement of Ballistic Gelatin Impact Using an Instrumented Tube

Science.gov (United States)

Seidt, J. D.; Periira, J. M.; Hammer, J. T.; Gilat, A.; Ruggeri, C. R.

2012-01-01

Bird strikes are a common problem for the aerospace industry and can cause serious damage to an aircraft. Ballistic gelatin is frequently used as a surrogate for actual bird carcasses in bird strike tests. Numerical simulations of these tests are used to supplement experimental data, therefore it is necessary to use numerical modeling techniques that can accurately capture the dynamic response of ballistic gelatin. An experimental technique is introduced to validate these modeling techniques. A ballistic gelatin projectile is fired into a strike plate attached to a 36 in. long sensor tube. Dynamic load is measured at two locations relative to the strike plate using strain gages configured in a full Wheatstone bridge. Data from these experiments are used to validate a gelatin constitutive model. Simulations of the apparatus are analyzed to investigate its performance.

Mallow Fiber-Reinforced Epoxy Composites in Multilayered Armor for Personal Ballistic Protection

Science.gov (United States)

Nascimento, Lucio Fábio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Lima, Édio Pereira; da Luz, Fernanda Santos

2017-10-01

Lighter and less expensive polymer composites reinforced with natural fibers have been investigated as possible components of a multilayered armor system (MAS) for personal protection against high-velocity ammunition. Their ballistic performance was consistently found comparable with that of conventional Kevlar® synthetic aramid fiber. Among the numerous existing natural fibers with the potential for reinforcing polymer composites to replace Kevlar® in MAS, mallow fiber has not been fully investigated. Thus, the objective of this work is to evaluate the ballistic performance of epoxy composites reinforced with 30 vol.% of aligned mallow fibers as a second MAS layer backing a front ceramic plate. The results using high-velocity 7.62 ammunition show a similar indentation to a Kevlar® layer with the same thickness. An impedance matching calculation supports the similar ballistic performance of mallow fiber composite and Kevlar®. Reduced MAS costs associated with the mallow fiber composite are practical advantages over Kevlar®.

Coherent Charge Transport in Ballistic InSb Nanowire Josephson Junctions

Science.gov (United States)

Li, S.; Kang, N.; Fan, D. X.; Wang, L. B.; Huang, Y. Q.; Caroff, P.; Xu, H. Q.

2016-01-01

Hybrid InSb nanowire-superconductor devices are promising for investigating Majorana modes and topological quantum computation in solid-state devices. An experimental realisation of ballistic, phase-coherent superconductor-nanowire hybrid devices is a necessary step towards engineering topological superconducting electronics. Here, we report on a low-temperature transport study of Josephson junction devices fabricated from InSb nanowires grown by molecular-beam epitaxy and provide a clear evidence for phase-coherent, ballistic charge transport through the nanowires in the junctions. We demonstrate that our devices show gate-tunable proximity-induced supercurrent and clear signatures of multiple Andreev reflections in the differential conductance, indicating phase-coherent transport within the junctions. We also observe periodic modulations of the critical current that can be associated with the Fabry-Pérot interference in the nanowires in the ballistic transport regime. Our work shows that the InSb nanowires grown by molecular-beam epitaxy are of excellent material quality and hybrid superconducting devices made from these nanowires are highly desirable for investigation of the novel physics in topological states of matter and for applications in topological quantum electronics. PMID:27102689

Modeling internal ballistics of gas combustion guns.

Science.gov (United States)

Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

2016-05-01

Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur.

"Ballistic Six" Upper-Extremity Plyometric Training for the Pediatric Volleyball Players.

Science.gov (United States)

Turgut, Elif; Cinar-Medeni, Ozge; Colakoglu, Filiz F; Baltaci, Gul

2017-09-19

The Ballistic Six exercise program includes commonly used upper-body exercises, and the program is recommended for overhead throwing athletes. The purpose of the current study was to investigate the effects of a 12-week the Ballistic Six upper-extremity plyometric training program on upper-body explosive power, endurance, and reaction time in pediatric overhead athletes. Twenty-eight female pediatric volleyball players participated in the study. The participants were randomly divided into 2 study groups: an intervention group (upper-extremity plyometric training in addition to the volleyball training; n = 14) and a control group (the volleyball training only; n = 14). All the participants were assessed before and after a 12-week training program for upper-body power, strength and endurance, and reaction time. Statistical comparison was performed using an analysis of variance test. Comparisons showed that after a 12-week training program, the Ballistic Six upper-body plyometric training program resulted in more improvements in an overhead medicine ball throwing distance and a push-up performance, as well as greater improvements in the reaction time in the nonthrowing arm when compared with control training. In addition, a 12-week training program was found to be effective in achieving improvements in the reaction time in the throwing arm for both groups similarly. Compared with regular training, upper-body plyometric training resulted in additional improvements in upper-body power and strength and endurance among pediatric volleyball players. The findings of the study provide a basis for developing training protocols for pediatric volleyball players.

Effects of Strength vs. Ballistic-Power Training on Throwing Performance.

Science.gov (United States)

Zaras, Nikolaos; Spengos, Konstantinos; Methenitis, Spyridon; Papadopoulos, Constantinos; Karampatsos, Giorgos; Georgiadis, Giorgos; Stasinaki, Aggeliki; Manta, Panagiota; Terzis, Gerasimos

2013-01-01

The purpose of the present study was to investigate the effects of 6 weeks strength vs. ballistic-power (Power) training on shot put throwing performance in novice throwers. Seventeen novice male shot-put throwers were divided into Strength (N = 9) and Power (n = 8) groups. The following measurements were performed before and after the training period: shot put throws, jumping performance (CMJ), Wingate anaerobic performance, 1RM strength, ballistic throws and evaluation of architectural and morphological characteristics of vastus lateralis. Throwing performance increased significantly but similarly after Strength and Power training (7.0-13.5% vs. 6.0-11.5%, respectively). Muscular strength in leg press increased more after Strength than after Power training (43% vs. 21%, respectively), while Power training induced an 8.5% increase in CMJ performance and 9.0 - 25.8% in ballistic throws. Peak power during the Wingate test increased similarly after Strength and Power training. Muscle thickness increased only after Strength training (10%, p ballistic power training in novice throwers, but with dissimilar muscular adaptations. Key pointsBallistic-power training with 30% of 1RM is equally effective in increasing shot put performance as strength training, in novice throwers, during a short training cycle of six weeks.In novice shot putters with relatively low initial muscle strength/mass, short-term strength training might be more important since it can increase both muscle strength and shot put performance.The ballistic type of power training resulted in a significant increase of the mass of type IIx muscle fibres and no change in their proportion. Thus, this type of training might be used effectively during the last weeks before competition, when the strength training load is usually reduced, in order to increase muscle power and shot put performance in novice shot putters.

Coherent Control of Nanoscale Ballistic Currents in Transition Metal Dichalcogenide ReS2.

Science.gov (United States)

Cui, Qiannan; Zhao, Hui

2015-04-28

Transition metal dichalcogenides are predicted to outperform traditional semiconductors in ballistic devices with nanoscale channel lengths. So far, experimental studies on charge transport in transition metal dichalcogenides are limited to the diffusive regime. Here we show, using ReS2 as an example, all-optical injection, detection, and coherent control of ballistic currents. By utilizing quantum interference between one-photon and two-photon interband transition pathways, ballistic currents are injected in ReS2 thin film samples by a pair of femtosecond laser pulses. We find that the current decays on an ultrafast time scale, resulting in an electron transport of only a fraction of one nanometer. Following the relaxation of the initially injected momentum, backward motion of the electrons for about 1 ps is observed, driven by the Coulomb force from the oppositely moved holes. We also show that the injected current can be controlled by the phase of the laser pulses. These results demonstrate a new platform to study ballistic transport of nonequilibrium carriers in transition metal dichalcogenides.

Ballistic materials in MR imaging

International Nuclear Information System (INIS)

Smith, A.S.; Hurst, G.C.; Duerk, J.L.; Diaz, P.J.

1990-01-01

This paper reports on the most common ballistic materials available in the urban setting studied for deflection force, rotation, heating, and imaging artifact at 1.5 T to determine potential efficacy and safety for imaging patients with ballistic injuries. Twenty-eight missiles were tested, covering the range of bullet types and materials suggested by the Cleveland Police Department. Deflection force was measured by the New method. Rotation was studied by evaluating bullets in a 10% (W/W) ballistic gelating after 30 minutes with the long axis of the bullet placed parallel and perpendicular to the z axis. Heating was measured with alcohol thermometers imaged for 1 hour alternately with FESUM and spin-echo sequences (RF absorption w/Kg and 0.033 w/Kg). Image artifact evaluation of routine sequences was performed

Metallographic characterisation of Al6061-T6 aluminium plates subjected to ballistic impact

International Nuclear Information System (INIS)

Manes, A.; Pagani, M.; Saponara, M.; Mombelli, D.; Mapelli, C.; Giglio, M.

2014-01-01

Al6061-T6 aluminium single layer plates, of different thickness, impacted by two different 7.62 mm Armour Piercing projectiles are studied from a metallographic point of view. The material behaviour after ballistic impact is investigated by optical and scanning electron microscopy as well as by micro-hardness tests. The study allows one to highlight the physical phenomena that happen during the impact: the formation of adiabatic shear bands (ASB), the evolution of softening and hardening phenomena, the creation of petalling, plugging and the formation of a melted film between the target and the penetrator as well as the localised failure mechanism. The thermo-mechanical effects on the target and the penetrator material have been examined in order to investigate in the physical phenomena ruling the ballistic damage; the differences between the two types of impactors are also highlighted. Among interesting findings, it has been noticed that a complete penetration is less detrimental and tungsten core projectile seems more damaging for the structural integrity of Al6061-T6 plates. A complete penetration allows the material to better dissipate the plastic deformation energy induced by bullet whereas the arrest increases localised material softening effect resulting in the formation of ASB. Although the creation of numerical models is not the aim of the present paper, the findings could be useful for the building of a modelling approach capable of replicating all the involved phenomena in details

Metallographic characterisation of Al6061-T6 aluminium plates subjected to ballistic impact

Energy Technology Data Exchange (ETDEWEB)

Manes, A., E-mail: andrea.manes@polimi.it; Pagani, M.; Saponara, M.; Mombelli, D.; Mapelli, C.; Giglio, M.

2014-07-01

Al6061-T6 aluminium single layer plates, of different thickness, impacted by two different 7.62 mm Armour Piercing projectiles are studied from a metallographic point of view. The material behaviour after ballistic impact is investigated by optical and scanning electron microscopy as well as by micro-hardness tests. The study allows one to highlight the physical phenomena that happen during the impact: the formation of adiabatic shear bands (ASB), the evolution of softening and hardening phenomena, the creation of petalling, plugging and the formation of a melted film between the target and the penetrator as well as the localised failure mechanism. The thermo-mechanical effects on the target and the penetrator material have been examined in order to investigate in the physical phenomena ruling the ballistic damage; the differences between the two types of impactors are also highlighted. Among interesting findings, it has been noticed that a complete penetration is less detrimental and tungsten core projectile seems more damaging for the structural integrity of Al6061-T6 plates. A complete penetration allows the material to better dissipate the plastic deformation energy induced by bullet whereas the arrest increases localised material softening effect resulting in the formation of ASB. Although the creation of numerical models is not the aim of the present paper, the findings could be useful for the building of a modelling approach capable of replicating all the involved phenomena in details.

Ballistic missile defense effectiveness

Science.gov (United States)

Lewis, George N.

2017-11-01

The potential effectiveness of ballistic missile defenses today remains a subject of debate. After a brief discussion of terminal and boost phase defenses, this chapter will focus on long-range midcourse defenses. The problems posed by potential countermeasures to such midcourse defenses are discussed as are the sensor capabilities a defense might have available to attempt to discriminate the actual missile warhead in a countermeasures environment. The role of flight testing in assessing ballistic missile defense effectiveness is discussed. Arguments made about effectiveness by missile defense supporters and critics are summarized.

Two distinct ballistic processes in graphene

International Nuclear Information System (INIS)

Lewkowicz, M; Rosenstein, B; Nghiem, D

2012-01-01

A dynamical approach to ballistic transport in mesoscopic graphene samples of finite length Land contact potential difference with leads U is developed. It is shown that at ballistic times shorter than both relevant time scales, t L = L/v g (v g - Fermi velocity) and t u = ħ/(eU), the major effect of electric field is to creates the electron - hole pairs, namely causes interband transitions. At ballistic times lager than the two scales the mechanism is very different. The conductivity has its “nonrelativistic” or intraband value equal to the one obtained within the Landauer-Butticker approach for the barrier Uresulting from evanescent waves tunneling through the barrier.

Relationship between traditional and ballistic squat exercise with vertical jumping and maximal sprinting.

Science.gov (United States)

Requena, Bernardo; García, Inmaculada; Requena, Francisco; de Villarreal, Eduardo Sáez-Sáez; Cronin, John B

2011-08-01

The purpose of this study was to quantify the magnitude of the relationship between vertical jumping and maximal sprinting at different distances with performance in the traditional and ballistic concentric squat exercise in well-trained sprinters. Twenty-one men performed 2 types of barbell squats (ballistic and traditional) across different loads with the aim of determining the maximal peak and average power outputs and 1 repetition maximum (1RM) values. Moreover, vertical jumping (countermovement jump test [CMJ]) and maximal sprints over 10, 20, 30, 40, 60, and 80 m were also assessed. In respect to 1RM in traditional squat, (a) no significant correlation was found with CMJ performance; (b) positive strong relationships (p ballistic and traditional squat exercises (r = 0.53-0.90); (c) negative significant correlations (r = -0.49 to -0.59, p ballistic or traditional squat exercises. Sprint time at 20 m was only related to ballistic and traditional squat performance when power values were expressed in relative terms. Moderate significant correlations (r = -0.39 to -0.56, p ballistic and traditional squat exercises. Sprint times at 60 and 80 m were mainly related to ballistic squat power outputs. Although correlations can only give insights into associations and not into cause and effect, from this investigation, it can be seen that traditional squat strength has little in common with CMJ performance and that relative 1RM and power outputs for both squat exercises are statistically correlated to most sprint distances underlying the importance of strength and power to sprinting.

Terminal ballistics

CERN Document Server

Rosenberg, Zvi

2016-01-01

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

Ballistic self-annealing during ion implantation

International Nuclear Information System (INIS)

Prins, Johan F.

2001-01-01

Ion implantation conditions are considered during which the energy, dissipated in the collision cascades, is low enough to ensure that the defects, which are generated during these collisions, consist primarily of vacancies and interstitial atoms. It is proposed that ballistic self-annealing is possible when the point defect density becomes high enough, provided that none, or very few, of the interstitial atoms escape from the layer being implanted. Under these conditions, the fraction of ballistic atoms, generated within the collision cascades from substitutional sites, decreases with increasing ion dose. Furthermore, the fraction of ballistic atoms, which finally end up within vacancies, increases with increasing vacancy density. Provided the crystal structure does not collapse, a damage threshold should be approached where just as many atoms are knocked out of substitutional sites as the number of ballistic atoms that fall back into vacancies. Under these conditions, the average point defect density should approach saturation. This model is applied to recently published Raman data that have been measured on a 3 MeV He + -ion implanted diamond (Orwa et al 2000 Phys. Rev. B 62 5461). The conclusion is reached that this ballistic self-annealing model describes the latter data better than a model in which it is assumed that the saturation in radiation damage is caused by amorphization of the implanted layer. (author)

Scale effects on quasi-steady solid rocket internal ballistic behaviour

Energy Technology Data Exchange (ETDEWEB)

Greatrix, D. R. [Department of Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B2K3 (Canada)

2010-11-15

The ability to predict with some accuracy a given solid rocket motor's performance before undertaking one or several costly experimental test firings is important. On the numerical prediction side, as various component models evolve, their incorporation into an overall internal ballistics simulation program allows for new motor firing simulations to take place, which in turn allows for updated comparisons to experimental firing data. In the present investigation, utilizing an updated simulation program, the focus is on quasi-steady performance analysis and scale effects (influence of motor size). The predicted effects of negative/positive erosive burning and propellant/casing deflection, as tied to motor size, on a reference cylindrical-grain motor's internal ballistics, are included in this evaluation. Propellant deflection has only a minor influence on the reference motor's internal ballistics, regardless of motor size. Erosive burning, on the other hand, is distinctly affected by motor scale. (author)

The National Research Council study: "Making sense of ballistic missile defense"

Science.gov (United States)

Wilkening, Dean A.

2014-05-01

This chapter explains and summarizes the main findings of a recent National Research Council study entitled Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives.

Ballistic Test Facility

Data.gov (United States)

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

Temperature dependence of ballistic mobility in a metamorphic InGaAs/InAlAs high electron mobility transistor

International Nuclear Information System (INIS)

Lee, Jongkyong; Gang, Suhyun; Jo, Yongcheol; Kim, Jongmin; Woo, Hyeonseok; Han, Jaeseok; Kim, Hyungsang; Im, Hyunsik

2014-01-01

We have investigated the temperature dependence of ballistic mobility in a 100 nm-long InGaAs/InAlAs metamorphic high-electron-mobility transistor designed for millimeter-wavelength RF applications. To extract the temperature dependence of quasi-ballistic mobility, our experiment involves measurements of the effective mobility in the low-bias linear region of the transistor and of the collision-dominated Hall mobility using a gated Hall bar of the same epitaxial structure. The data measured from the experiment are consistent with that of modeled ballistic mobility based on ballistic transport theory. These results advance the understanding of ballistic transport in various transistors with a nano-scale channel length that is comparable to the carrier's mean free path in the channel.

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

Energy Technology Data Exchange (ETDEWEB)

Taylor, Paul A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-11-01

Light body armor development for the warfighter is based on trial-and-error testing of prototype designs against ballistic projectiles. Torso armor testing against blast is nonexistent but necessary to protect the heart and lungs. In tests against ballistic projectiles, protective apparel is placed over ballistic clay and the projectiles are fired into the armor/clay target. The clay represents the human torso and its behind-armor, permanent deflection is the principal metric used to assess armor protection. Although this approach provides relative merit assessment of protection, it does not examine the behind-armor blunt trauma to crucial torso organs. We propose a modeling and simulation (M&S) capability for wound injury scenarios to the head, neck, and torso of the warfighter. We will use this toolset to investigate the consequences of, and mitigation against, blast exposure, blunt force impact, and ballistic projectile penetration leading to damage of critical organs comprising the central nervous, cardiovascular, and respiratory systems. We will leverage Sandia codes and our M&S expertise on traumatic brain injury to develop virtual anatomical models of the head, neck, and torso and the simulation methodology to capture the physics of wound mechanics. Specifically, we will investigate virtual wound injuries to the head, neck, and torso without and with protective armor to demonstrate the advantages of performing injury simulations for the development of body armor. The proposed toolset constitutes a significant advance over current methods by providing a virtual simulation capability to investigate wound injury and optimize armor design without the need for extensive field testing.

Preservation and storage of prepared ballistic gelatine.

Science.gov (United States)

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

2016-02-01

The use of ballistic gelatine, generally accepted as a human muscle tissue simulant in wound ballistic studies, might be improved by adding a preservative (Methyl 4-hydroxybenzoate) which inhibits microbial growth. This study shows that replacing a part of the gelatine powder by the preservative does not significantly alter the penetration depth of projectiles. Storing prepared blocks of ballistic gelatine over time decreased the penetration depth of projectiles. Storage of prepared gelatine for 4 week already showed a significant effect on the penetration depth of projectiles. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Electron transport properties in InAs four-terminal ballistic junctions under weak magnetic fields

International Nuclear Information System (INIS)

Koyama, M.; Fujiwara, K.; Amano, N.; Maemoto, T.; Sasa, S.; Inoue, M.

2009-01-01

We report on the electron transport properties based on ballistic electrons under magnetic fields in four-terminal ballistic junctions fabricated on an InAs/AlGaSb heterostructure. The four-terminal junction structure is composed of two longitudinal stems with two narrow wires slanted with 30 degree from the perpendicular axis. The electron focusing peak was obtained with the bend resistance measurement. Then it was investigated the nonlinear electron transport property of potential difference between longitudinal stems due to ballistic electrons with applying direct current from narrow wires. Observed nonlinearity showed clear rectification effects which have negative polarity regardless of input voltage polarity. Although this nonlinearity was qualitatively changed due to the Lorentz force under magnetic fields, the degradation of ballistic effects on nonlinear properties were observed when the current increased to higher strength. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Ballistic deficit correction

International Nuclear Information System (INIS)

Duchene, G.; Moszynski, M.; Curien, D.

1991-01-01

The EUROGAM data-acquisition has to handle a large number of events/s. Typical in-beam experiments using heavy-ion fusion reactions assume the production of about 50 000 compound nuclei per second deexciting via particle and γ-ray emissions. The very powerful γ-ray detection of EUROGAM is expected to produce high-fold event rates as large as 10 4 events/s. Such high count rates introduce, in a common dead time mode, large dead times for the whole system associated with the processing of the pulse, its digitization and its readout (from the preamplifier pulse up to the readout of the information). In order to minimize the dead time the shaping time constant τ, usually about 3 μs for large volume Ge detectors has to be reduced. Smaller shaping times, however, will adversely affect the energy resolution due to ballistic deficit. One possible solution is to operate the linear amplifier, with a somewhat smaller shaping time constant (in the present case we choose τ = 1.5 μs), in combination with a ballistic deficit compensator. The ballistic deficit can be corrected in different ways using a Gated Integrator, a hardware correction or even a software correction. In this paper we present a comparative study of the software and hardware corrections as well as gated integration

Numerical simulation and optimized design of cased telescoped ammunition interior ballistic

Directory of Open Access Journals (Sweden)

Jia-gang Wang

2018-04-01

Full Text Available In order to achieve the optimized design of a cased telescoped ammunition (CTA interior ballistic design, a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA interior ballistic model. Aiming at the interior ballistic characteristics of a CTA gun, the goal of CTA interior ballistic design is to obtain a projectile velocity as large as possible. The optimal design of CTA interior ballistic is carried out using a genetic algorithm by setting peak pressure, changing the chamber volume and gun powder charge density. A numerical simulation of interior ballistics based on a 35 mm CTA firing experimental scheme was conducted and then the genetic algorithm was used for numerical optimization. The projectile muzzle velocity of the optimized scheme is increased from 1168 m/s for the initial experimental scheme to 1182 m/s. Then four optimization schemes were obtained with several independent optimization processes. The schemes were compared with each other and the difference between these schemes is small. The peak pressure and muzzle velocity of these schemes are almost the same. The result shows that the genetic algorithm is effective in the optimal design of the CTA interior ballistics. This work will be lay the foundation for further CTA interior ballistic design. Keywords: Cased telescoped ammunition, Interior ballistics, Gunpowder, Optimization genetic algorithm

Ballistic Missile Defense in Europe

OpenAIRE

Sarihan, Ali; Bush, Amy; Summers, Lawrence; Thompson, Brent; Tomasszewski, Steven

2009-01-01

This paper will build on ballistic missile defense in Europe. In the first part, a brief historical overview will place the current public management issue into light. This is followed by a discussion of the main actors in the international debate, the problems that arise and the available options and recommendations to address missile defense. In the second part, differences between George W. Bush and Barack H. Obama will analyze under the title “Ballistic Missile Defense in Europe: Evolving...

2015 Assessment of the Ballistic Missile Defense System (BMDS)

Science.gov (United States)

2016-04-01

Director, Operational Test and Evaluation 2015 Assessment of the Ballistic Missile Defense System (BMDS...Evaluation (DOT&E) as they pertain to the Ballistic Missile Defense System (BMDS). Congress specified these requirements in the fiscal year 2002 (FY02...systems are the Ground-based Midcourse Defense (GMD), Aegis Ballistic Missile Defense (Aegis BMD), Terminal High-Altitude Area Defense (THAAD), and

Advanced geometries for ballistic neutron guides

International Nuclear Information System (INIS)

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

2004-01-01

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

Modeling terminal ballistics using blending-type spline surfaces

Science.gov (United States)

Pedersen, Aleksander; Bratlie, Jostein; Dalmo, Rune

2014-12-01

We explore using GERBS, a blending-type spline construction, to represent deform able thin-plates and model terminal ballistics. Strategies to construct geometry for different scenarios of terminal ballistics are proposed.

Ballistic resistant article, semi-finished product for and method of making a shell for a ballistic resistant article

NARCIS (Netherlands)

Harings, Jules Armand Wilhelmina; Janse, Gerardus Hubertus Anna

2013-01-01

The invention relates to a ballistic resistant article, such as a helmet (1), comprising a double curved shell in turn comprising a stack (5) of layers (6) of an oriented anti-ballistic material, the layers comprising one or more plies and having a plurality of cuts (7), the ends of which define a

Ballistic resistant article, semi-finished product for and method of making a shell for a ballistic resistant article

NARCIS (Netherlands)

Harings, Jules; Janse, Gerardus

2013-01-01

The invention relates to a ballistic resistant article, such as a helmet (1), comprising a double curved shell (2) in turn comprising a stack (5) of layers (6) of an oriented anti-ballistic material, the layers (6) comprising one or more plies and having a plurality of cuts (7), the ends of which

Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

Directory of Open Access Journals (Sweden)

Sergio Neves Monteiro

2018-02-01

Full Text Available The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS. Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM. The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.

The strong thermoelectric effect in nanocarbon generated by the ballistic phonon drag of electrons

International Nuclear Information System (INIS)

Eidelman, E D; Vul', A Ya

2007-01-01

The thermoelectric power and thermoelectric figure of merit for carbon nanostructure consisting of graphite-like (sp 2 ) and diamond-like (sp 3 ) regions have been investigated. The probability of electron collisions with quasi-ballistic phonons in sp 2 regions has been analysed for the first time. We have shown that the probability is not small. We have analysed the influence of various factors on the process of the electron-ballistic phonon drag (the phonon drag effect). The thermoelectric power and thermoelectric figure of merit under conditions of ballistic transport were found to be substantially higher than those in the cases of drag by thermalized phonons and of electron diffusion. The thermoelectric figure of merit (ZT) in the case of a ballistic phonon contribution to the phonon drag of electrons should be 50 times that for chaotic phonons and 500 times that in the case of the diffusion process. In that case ZT should be a record (ZT≥2-3)

Impacts of Deflection Nose on Ballistic Trajectory Control Law

Directory of Open Access Journals (Sweden)

Bo Zhang

2014-01-01

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

Kevlar^TM Fiber-Reinforced Polybenzoxazine Alloys for Ballistic Impact Application

Directory of Open Access Journals (Sweden)

Chanchira Jubsilp

2011-10-01

Full Text Available A light weight ballistic composites from Kevlar^TM-reinforcing fiber having polybenzoxazine (BA/urethane prepolymer (PU alloys as a matrix were investigated in this work. The effect of alloy compositions on the ballistic composite properties was determined. The results revealed that the enhancement in the glass transition temperature (Tg of the Kevlar^TM-reinforced BA/PU composites compared to that of the Kevlar^TM-reinforced polybenzoxazine composite was observed. The increase of the elastomeric PU content in the BA/PU alloy resulted in samples with tougher characteristics. The storage modulus of the Kevlar^TM-reinforced BA/PU composites increased with increasing the mass fraction of polybenzoxazine. A ballistic impact test was also performed on the Kevlar^TM-reinforced BA/PU composites using a 9 mm handgun. It was found that the optimal contents of PU in the BA/PU alloys should be approximately 20wt%. The extent of the delaminated area and interfacial fracture were observed to change with the varied compositions of the matrix alloys. The appropriate thickness of Kevlar^TM-reinforced 80/20 BA/PU composite panel was 30 plies and 50 plies to resist the penetration from the ballistic impact equivalent to levels II-A and III-A of NIJ standard. The arrangement of composite panels with the higher stiffness panel at the front side also showed the best efficiency of ballistic penetration resistance.

On the comparison of the ballistic performance of 10% zirconia toughened alumina and 95% alumina ceramic target

International Nuclear Information System (INIS)

Zhang, X.F.; Li, Y.C.

2010-01-01

Ballistic performance of different type of ceramic materials subjected to high velocity impact was investigated in many theoretical, experimental and numerical studies. In this study, a comparison of ballistic performance of 95% alumina ceramic and 10% zirconia toughened alumina (ZTA) ceramic tiles was analyzed theoretically and experimentally. Spherical cavity model based on the concepts of mechanics of compressible porous media of Galanov was used to analyze the relation of target resistance and static mechanical properties. Experimental studies were carried out on the ballistic performance of above two types of ceramic tiles based on the depth of penetration (DOP) method, when subjected to normal impact of tungsten long rod projectiles. Typical damaged targets were presented. The residual depth of penetration on after-effect target was measured in all experiments, and the ballistic efficiency factor of above two types ceramic plates were determined. Both theoretical and experimental results show that the improvement on ballistic resistance was clearly observed by increasing fracture toughness in ZTA ceramics.

EFFECTS OF STRENGTH VS. BALLISTIC-POWER TRAINING ON THROWING PERFORMANCE

Directory of Open Access Journals (Sweden)

Nikolaos Zaras

2013-03-01

Full Text Available The purpose of the present study was to investigate the effects of 6 weeks strength vs. ballistic-power (Power training on shot put throwing performance in novice throwers. Seventeen novice male shot-put throwers were divided into Strength (N = 9 and Power (n = 8 groups. The following measurements were performed before and after the training period: shot put throws, jumping performance (CMJ, Wingate anaerobic performance, 1RM strength, ballistic throws and evaluation of architectural and morphological characteristics of vastus lateralis. Throwing performance increased significantly but similarly after Strength and Power training (7.0-13.5% vs. 6.0-11.5%, respectively. Muscular strength in leg press increased more after Strength than after Power training (43% vs. 21%, respectively, while Power training induced an 8.5% increase in CMJ performance and 9.0 - 25.8% in ballistic throws. Peak power during the Wingate test increased similarly after Strength and Power training. Muscle thickness increased only after Strength training (10%, p < 0.05. Muscle fibre Cross Sectional Area (fCSA increased in all fibre types after Strength training by 19-26% (p < 0.05, while only type IIx fibres hypertrophied significantly after Power training. Type IIx fibres (% decreased after Strength but not after Power training. These results suggest that shot put throwing performance can be increased similarly after six weeks of either strength or ballistic power training in novice throwers, but with dissimilar muscular adaptations

Quantum Mechanical Modeling of Ballistic MOSFETs

Science.gov (United States)

Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan (Technical Monitor)

2001-01-01

The objective of this project was to develop theory, approximations, and computer code to model quasi 1D structures such as nanotubes, DNA, and MOSFETs: (1) Nanotubes: Influence of defects on ballistic transport, electro-mechanical properties, and metal-nanotube coupling; (2) DNA: Model electron transfer (biochemistry) and transport experiments, and sequence dependence of conductance; and (3) MOSFETs: 2D doping profiles, polysilicon depletion, source to drain and gate tunneling, understand ballistic limit.

Ballistic transport and quantum interference in InSb nanowire devices

International Nuclear Information System (INIS)

Li Sen; Huang Guang-Yao; Guo Jing-Kun; Kang Ning; Xu Hong-Qi; Caroff, Philippe

2017-01-01

An experimental realization of a ballistic superconductor proximitized semiconductor nanowire device is a necessary step towards engineering topological quantum electronics. Here, we report on ballistic transport in InSb nanowires grown by molecular-beam epitaxy contacted by superconductor electrodes. At an elevated temperature, clear conductance plateaus are observed at zero magnetic field and in agreement with calculations based on the Landauer formula. At lower temperature, we have observed characteristic Fabry–Pérot patterns which confirm the ballistic nature of charge transport. Furthermore, the magnetoconductance measurements in the ballistic regime reveal a periodic variation related to the Fabry–Pérot oscillations. The result can be reasonably explained by taking into account the impact of magnetic field on the phase of ballistic electron’s wave function, which is further verified by our simulation. Our results pave the way for better understanding of the quantum interference effects on the transport properties of InSb nanowires in the ballistic regime as well as developing of novel device for topological quantum computations. (paper)

Ballistic negatron battery

Energy Technology Data Exchange (ETDEWEB)

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

2012-07-01

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

Cost of space-based laser ballistic missile defense.

Science.gov (United States)

Field, G; Spergel, D

1986-03-21

Orbiting platforms carrying infrared lasers have been proposed as weapons forming the first tier of a ballistic missile defense system under the President's Strategic Defense Initiative. As each laser platform can destroy a limited number of missiles, one of several methods of countering such a system is to increase the number of offensive missiles. Hence it is important to know whether the cost-exchange ratio, defined as the ratio of the cost to the defense of destroying a missile to the cost to the offense of deploying an additional missile, is greater or less than 1. Although the technology to be used in a ballistic missile defense system is still extremely uncertain, it is useful to examine methods for calculating the cost-exchange ratio. As an example, the cost of an orbiting infrared laser ballistic missile defense system employed against intercontinental ballistic missiles launched simultaneously from a small area is compared to the cost of additional offensive missiles. If one adopts lower limits to the costs for the defense and upper limits to the costs for the offense, the cost-exchange ratio comes out substantially greater than 1. If these estimates are confirmed, such a ballistic missile defense system would be unable to maintain its effectiveness at less cost than it would take to proliferate the ballistic missiles necessary to overcome it and would therefore not satisfy the President's requirements for an effective strategic defense. Although the method is illustrated by applying it to a space-based infrared laser system, it should be straightforward to apply it to other proposed systems.

Evaluation of bone surrogates for indirect and direct ballistic fractures.

Science.gov (United States)

Bir, Cynthia; Andrecovich, Chris; DeMaio, Marlene; Dougherty, Paul J

2016-04-01

The mechanism of injury for fractures to long bones has been studied for both direct ballistic loading as well as indirect. However, the majority of these studies have been conducted on both post-mortem human subjects (PMHS) and animal surrogates which have constraints in terms of storage, preparation and testing. The identification of a validated bone surrogate for use in forensic, medical and engineering testing would provide the ability to investigate ballistic loading without these constraints. Two specific bone surrogates, Sawbones and Synbone, were evaluated in comparison to PMHS for both direct and indirect ballistic loading. For the direct loading, the mean velocity to produce fracture was 121 ± 19 m/s for the PMHS, which was statistically different from the Sawbones (140 ± 7 m/s) and Synbone (146 ± 3 m/s). The average distance to fracture in the indirect loading was .70 cm for the PMHS. The Synbone had a statistically similar average distance to fracture (.61 cm, p=0.54) however the Sawbones average distance to fracture was statistically different (.41 cm, pballistic testing was not identified and future work is warranted. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Nonlinear Ballistic Transport in an Atomically Thin Material.

Science.gov (United States)

Boland, Mathias J; Sundararajan, Abhishek; Farrokhi, M Javad; Strachan, Douglas R

2016-01-26

Ultrashort devices that incorporate atomically thin components have the potential to be the smallest electronics. Such extremely scaled atomically thin devices are expected to show ballistic nonlinear behavior that could make them tremendously useful for ultrafast applications. While nonlinear diffusive electron transport has been widely reported, clear evidence for intrinsic nonlinear ballistic transport in the growing array of atomically thin conductors has so far been elusive. Here we report nonlinear electron transport of an ultrashort single-layer graphene channel that shows quantitative agreement with intrinsic ballistic transport. This behavior is shown to be distinctly different than that observed in similarly prepared ultrashort devices consisting, instead, of bilayer graphene channels. These results suggest that the addition of only one extra layer of an atomically thin material can make a significant impact on the nonlinear ballistic behavior of ultrashort devices, which is possibly due to the very different chiral tunneling of their charge carriers. The fact that we observe the nonlinear ballistic response at room temperature, with zero applied magnetic field, in non-ultrahigh vacuum conditions and directly on a readily accessible oxide substrate makes the nanogap technology we utilize of great potential for achieving extremely scaled high-speed atomically thin devices.

Direct measurement of the ballistic motion of a freely floating colloid in Newtonian and viscoelastic fluids.

Science.gov (United States)

Hammond, Andrew P; Corwin, Eric I

2017-10-01

A thermal colloid suspended in a liquid will transition from a short-time ballistic motion to a long-time diffusive motion. However, the transition between ballistic and diffusive motion is highly dependent on the properties and structure of the particular liquid. We directly observe a free floating tracer particle's ballistic motion and its transition to the long-time regime in both a Newtonian fluid and a viscoelastic Maxwell fluid. We examine the motion of the free particle in a Newtonian fluid and demonstrate a high degree of agreement with the accepted Clercx-Schram model for motion in a dense fluid. Measurements of the functional form of the ballistic-to-diffusive transition provide direct measurements of the temperature, viscosity, and tracer radius. We likewise measure the motion in a viscoelastic Maxwell fluid and find a significant disagreement between the theoretical asymptotic behavior and our measured values of the microscopic properties of the fluid. We observe a greatly increased effective mass for a freely moving particle and a decreased plateau modulus.

Effect of measurement on the ballistic-diffusive transition in turbid media.

Science.gov (United States)

Glasser, Ziv; Yaroshevsky, Andre; Barak, Bavat; Granot, Er'el; Sternklar, Shmuel

2013-10-01

The dependence of the transition between the ballistic and the diffusive regimes of turbid media on the experimental solid angle of the detection system is analyzed theoretically and experimentally. A simple model is developed which shows the significance of experimental conditions on the location of the ballistic-diffusive transition. It is demonstrated that decreasing the solid angle expands the ballistic regime; however, this benefit is bounded by the initial Gaussian beam diffraction. In addition, choosing the appropriate wavelength according to the model's principles provides another means of expanding the ballistic regime. Consequently, by optimizing the experimental conditions, it should be possible to extract the ballistic image of a tissue with a thickness of 1 cm.

Ballistic thermophoresis of adsorbates on free-standing graphene.

Science.gov (United States)

Panizon, Emanuele; Guerra, Roberto; Tosatti, Erio

2017-08-22

The textbook thermophoretic force which acts on a body in a fluid is proportional to the local temperature gradient. The same is expected to hold for the macroscopic drift behavior of a diffusive cluster or molecule physisorbed on a solid surface. The question we explore here is whether that is still valid on a 2D membrane such as graphene at short sheet length. By means of a nonequilibrium molecular dynamics study of a test system-a gold nanocluster adsorbed on free-standing graphene clamped between two temperatures [Formula: see text] apart-we find a phoretic force which for submicron sheet lengths is parallel to, but basically independent of, the local gradient magnitude. This identifies a thermophoretic regime that is ballistic rather than diffusive, persisting up to and beyond a 100-nanometer sheet length. Analysis shows that the phoretic force is due to the flexural phonons, whose flow is known to be ballistic and distance-independent up to relatively long mean-free paths. However, ordinary harmonic phonons should only carry crystal momentum and, while impinging on the cluster, should not be able to impress real momentum. We show that graphene and other membrane-like monolayers support a specific anharmonic connection between the flexural corrugation and longitudinal phonons whose fast escape leaves behind a 2D-projected mass density increase endowing the flexural phonons, as they move with their group velocity, with real momentum, part of which is transmitted to the adsorbate through scattering. The resulting distance-independent ballistic thermophoretic force is not unlikely to possess practical applications.

Quantum ballistic evolution in quantum mechanics: Application to quantum computers

International Nuclear Information System (INIS)

Benioff, P.

1996-01-01

Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single-step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators T is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e., motion restricted to a collection of nonintersecting or distinct paths on an arbitrary basis. The main goal of this paper is proof of a theorem which gives necessary and sufficient conditions that T must satisfy so that there exists a Hamiltonian description of quantum ballistic evolution for the process, namely, that T is a partial isometry and is orthogonality preserving and stable on some basis. Simple examples of quantum ballistic evolution for quantum Turing machines with one and with more than one type of elementary step are discussed. It is seen that for nondeterministic machines the basis set can be quite complex with much entanglement present. It is also proven that, given a step operator T for an arbitrary deterministic quantum Turing machine, it is decidable if T is stable and orthogonality preserving, and if quantum ballistic evolution is possible. The proof fails if T is a step operator for a nondeterministic machine. It is an open question if such a decision procedure exists for nondeterministic machines. This problem does not occur in classical mechanics. Also the definition of quantum Turing machines used here is compared with that used by other authors. copyright 1996 The American Physical Society

A ballistic mission to fly by Comet Halley

Science.gov (United States)

Boain, R. J.; Hastrup, R. C.

1980-01-01

The paper describes the available options, ballistic trajectory opportunities, and a preliminary reference trajectory that were selected as a basis for spacecraft design studies and programmatic planning for a Halley ballistic intercept mission in 1986. The paper also presents trajectory, performance, and navigation data which support the preliminary selection.

Space-based ballistic-missile defense

International Nuclear Information System (INIS)

Bethe, H.A.; Garwin, R.L.; Gottfried, K.; Kendall, H.W.

1984-01-01

This article, based on a forthcoming book by the Union for Concerned Scientists, focuses on the technical aspects of the issue of space-based ballistic-missile defense. After analysis, the authors conclude that the questionable performance of the proposed defense, the ease with which it could be overwhelmed or circumvented, and its potential as an antisatellite system would cause grievous damage to the security of the US if the Strategic Defense Initiative were to be pursued. The path toward greater security lies in quite another direction, they feel. Although research on ballistic-missile defense should continue at the traditional level of expenditure and within the constraints of the ABM Treaty, every effort should be made to negotiate a bilateral ban on the testing and use of space weapons. The authors think it is essential that such an agreement cover all altitudes, because a ban on high-altitude antisatellite weapons alone would not viable if directed energy weapons were developed for ballistic-missile defense. Further, the Star Wars program, unlikely ever to protect the entire nation against a nuclear attack, would nonetheless trigger a major expansion of the arms race

Ballistic food transport in toucans.

Science.gov (United States)

Baussart, Sabine; Korsoun, Leonid; Libourel, Paul-Antoine; Bels, Vincent

2009-08-01

The basic mechanism of food transport in tetrapods is lingual-based. Neognathous birds use this mechanism for exploiting a large diversity of food resources, whereas paleognathous birds use cranioinertial mechanism with or without tongue involvement. Food transport in two neognathous species of toucans (Ramphastos toco and R. vitellinus) is defined as ballistic transport mechanism. Only one transport cycle is used for moving the food from the tip of the beak to the pharynx. The food is projected between jaws with similar initial velocity in both species. At the time of release, the angle between trajectory of food position and horizontal is higher in R. vitellinus with a shorter beak than in R. toco. The tongue never makes contact with the food nor is it used to expand the buccal cavity. Tongue movement is associated with throat expansion, permitting the food to reach the entrance of the esophagus at the end of the ballistic trajectory. Selection of large food items in the diet may explain the evolutionary trend of using ballistic transport in the feeding behavior of toucans, which plays a key role in ecology of tropical forest. 2009 Wiley-Liss, Inc.

Ballistic trauma: lessons learned from iraq and afghanistan.

Science.gov (United States)

Shin, Emily H; Sabino, Jennifer M; Nanos, George P; Valerio, Ian L

2015-02-01

Management of upper extremity injuries secondary to ballistic and blast trauma can lead to challenging problems for the reconstructive surgeon. Given the recent conflicts in Iraq and Afghanistan, advancements in combat-casualty care, combined with a high-volume experience in the treatment of ballistic injuries, has led to continued advancements in the treatment of the severely injured upper extremity. There are several lessons learned that are translatable to civilian trauma centers and future conflicts. In this article, the authors provide an overview of the physics of ballistic injuries and principles in the management of such injuries through experience gained from military involvement in Iraq and Afghanistan.

Ballistic transport in graphene grown by chemical vapor deposition

International Nuclear Information System (INIS)

Calado, V. E.; Goswami, S.; Xu, Q.; Vandersypen, L. M. K.; Zhu, Shou-En; Janssen, G. C. A. M.; Watanabe, K.; Taniguchi, T.

2014-01-01

In this letter, we report the observation of ballistic transport on micron length scales in graphene synthesised by chemical vapour deposition (CVD). Transport measurements were done on Hall bar geometries in a liquid He cryostat. Using non-local measurements, we show that electrons can be ballistically directed by a magnetic field (transverse magnetic focussing) over length scales of ∼1 μm. Comparison with atomic force microscope measurements suggests a correlation between the absence of wrinkles and the presence of ballistic transport in CVD graphene

Ballistic transport in graphene grown by chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Calado, V. E.; Goswami, S.; Xu, Q.; Vandersypen, L. M. K., E-mail: l.m.k.vandersypen@tudelft.nl [Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft (Netherlands); Zhu, Shou-En; Janssen, G. C. A. M. [Micro and Nano Engineering Laboratory, Precision and Microsystems Engineering, Delft University of Technology, 2628 CD Delft (Netherlands); Watanabe, K.; Taniguchi, T. [Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

2014-01-13

In this letter, we report the observation of ballistic transport on micron length scales in graphene synthesised by chemical vapour deposition (CVD). Transport measurements were done on Hall bar geometries in a liquid He cryostat. Using non-local measurements, we show that electrons can be ballistically directed by a magnetic field (transverse magnetic focussing) over length scales of ∼1 μm. Comparison with atomic force microscope measurements suggests a correlation between the absence of wrinkles and the presence of ballistic transport in CVD graphene.

Missile Defense: Ballistic Missile Defense System Testing Delays Affect Delivery of Capabilities

Science.gov (United States)

2016-04-28

Page 1 GAO-16-339R Ballistic Missile Defense 441 G St. N.W. Washington, DC 20548 April 28, 2016 Congressional Committees Missile Defense... Ballistic Missile Defense System Testing Delays Affect Delivery of Capabilities For over half a century, the Department of Defense (DOD) has been...funding efforts to develop a system to detect, track, and defeat enemy ballistic missiles. The current system—the Ballistic Missile Defense System

Room-temperature ballistic energy transport in molecules with repeating units

Energy Technology Data Exchange (ETDEWEB)

Rubtsova, Natalia I.; Nyby, Clara M.; Zhang, Hong; Zhang, Boyu; Zhou, Xiao; Jayawickramarajah, Janarthanan; Burin, Alexander L.; Rubtsov, Igor V., E-mail: irubtsov@tulane.edu [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States)

2015-06-07

In materials, energy can propagate by means of two limiting regimes: diffusive and ballistic. Ballistic energy transport can be fast and efficient and often occurs with a constant speed. Using two-dimensional infrared spectroscopy methods, we discovered ballistic energy transport via individual polyethylene chains with a remarkably high speed of 1440 m/s and the mean free path length of 14.6 Å in solution at room temperature. Whereas the transport via the chains occurs ballistically, the mechanism switches to diffusive with the effective transport speed of 130 m/s at the end-groups attached to the chains. A unifying model of the transport in molecules is presented with clear time separation and additivity among the transport along oligomeric fragments, which occurs ballistically, and the transport within the disordered fragments, occurring diffusively. The results open new avenues for making novel elements for molecular electronics, including ultrafast energy transporters, controlled chemical reactors, and sub-wavelength quantum nanoseparators.

Room-temperature ballistic energy transport in molecules with repeating units

International Nuclear Information System (INIS)

Rubtsova, Natalia I.; Nyby, Clara M.; Zhang, Hong; Zhang, Boyu; Zhou, Xiao; Jayawickramarajah, Janarthanan; Burin, Alexander L.; Rubtsov, Igor V.

2015-01-01

In materials, energy can propagate by means of two limiting regimes: diffusive and ballistic. Ballistic energy transport can be fast and efficient and often occurs with a constant speed. Using two-dimensional infrared spectroscopy methods, we discovered ballistic energy transport via individual polyethylene chains with a remarkably high speed of 1440 m/s and the mean free path length of 14.6 Å in solution at room temperature. Whereas the transport via the chains occurs ballistically, the mechanism switches to diffusive with the effective transport speed of 130 m/s at the end-groups attached to the chains. A unifying model of the transport in molecules is presented with clear time separation and additivity among the transport along oligomeric fragments, which occurs ballistically, and the transport within the disordered fragments, occurring diffusively. The results open new avenues for making novel elements for molecular electronics, including ultrafast energy transporters, controlled chemical reactors, and sub-wavelength quantum nanoseparators

Sub-ballistic behavior in the quantum kicked rotor

Energy Technology Data Exchange (ETDEWEB)

Romanelli, A. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, C.C. 30, C.P. 11000, Montevideo (Uruguay)]. E-mail: alejo@fing.edu.uy; Auyuanet, A. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, C.C. 30, C.P. 11000, Montevideo (Uruguay)]. E-mail: auyuanet@fing.edu.uy; Siri, R. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, C.C. 30, C.P. 11000, Montevideo (Uruguay)]. E-mail: rsiri@fing.edu.uy; Micenmacher, V. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, C.C. 30, C.P. 11000, Montevideo (Uruguay)]. E-mail: vmd@fing.edu.uy

2007-05-28

We study the resonances of the quantum kicked rotor subjected to an excitation that follows an aperiodic Fibonacci prescription. In such a case the secondary resonances show a sub-ballistic behavior like the quantum walk with the same aperiodic prescription for the coin. The principal resonances maintain the well-known ballistic behavior.

Sub-ballistic behavior in the quantum kicked rotor

International Nuclear Information System (INIS)

Romanelli, A.; Auyuanet, A.; Siri, R.; Micenmacher, V.

2007-01-01

We study the resonances of the quantum kicked rotor subjected to an excitation that follows an aperiodic Fibonacci prescription. In such a case the secondary resonances show a sub-ballistic behavior like the quantum walk with the same aperiodic prescription for the coin. The principal resonances maintain the well-known ballistic behavior

Electron transport in InAs/AlGaSb ballistic rectifiers

International Nuclear Information System (INIS)

Maemoto, Toshihiko; Koyama, Masatoshi; Furukawa, Masashi; Takahashi, Hiroshi; Sasa, Shigehiko; Inoue, Masataka

2006-01-01

Nonlinear transport properties of a ballistic rectifier fabricated from InAs/AlGaSb heterostructures are reported. The operation of the ballistic rectifier is based on the guidance of carriers by a square anti-dot structure. The structure was defined by electron beam lithography and wet chemical etching. The DC characteristics and magneto-transport properties of the ballistic rectifier have been measured at 77 K and 4.2 K. Rectification effects relying on the ballistic transport were observed. From the four-terminal resistance measured at low magnetic fields, we also observed magneto-resistance fluctuations corresponding to the electron trajectories and symmetry-breaking electron scattering, which are influenced by the magnetic field strength

Effect of tempering time on the ballistic performance of a high strength armour steel

OpenAIRE

Jena, Pradipta Kumar; Senthil P., Ponguru; K., Siva Kumar

2016-01-01

The investigation describes and analyses the effect of tempering time on the mechanical and ballistic performance of a high strength armour steel. The steel is subjected to tempering at 300 °C for 2, 24 and 48 h. A marginal variation in strength and hardness is observed with increase in tempering time, whereas ductility and Charpy impact values are found to be decreasing. Ballistic performance of the samples are evaluated by impacting 7.62 mm and 12.7 mm armour piercing projectiles at 0° angl...

Design and Manufacturing Process for a Ballistic Missile

Directory of Open Access Journals (Sweden)

Zaharia Sebastian Marian

2016-12-01

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

Ballistic Anisotropic Magnetoresistance of Single-Atom Contacts.

Science.gov (United States)

Schöneberg, J; Otte, F; Néel, N; Weismann, A; Mokrousov, Y; Kröger, J; Berndt, R; Heinze, S

2016-02-10

Anisotropic magnetoresistance, that is, the sensitivity of the electrical resistance of magnetic materials on the magnetization direction, is expected to be strongly enhanced in ballistic transport through nanoscale junctions. However, unambiguous experimental evidence of this effect is difficult to achieve. We utilize single-atom junctions to measure this ballistic anisotropic magnetoresistance (AMR). Single Co and Ir atoms are deposited on domains and domain walls of ferromagnetic Fe layers on W(110) to control their magnetization directions. They are contacted with nonmagnetic tips in a low-temperature scanning tunneling microscope to measure the junction conductances. Large changes of the magnetoresistance occur from the tunneling to the ballistic regime due to the competition of localized and delocalized d-orbitals, which are differently affected by spin-orbit coupling. This work shows that engineering the AMR at the single atom level is feasible.

Effects of acute static, ballistic, and PNF stretching exercise on the muscle and tendon tissue properties.

Science.gov (United States)

Konrad, A; Stafilidis, S; Tilp, M

2017-10-01

The purpose of this study was to investigate the influence of a single static, ballistic, or proprioceptive neuromuscular facilitation (PNF) stretching exercise on the various muscle-tendon parameters of the lower leg and to detect possible differences in the effects between the methods. Volunteers (n = 122) were randomly divided into static, ballistic, and PNF stretching groups and a control group. Before and after the 4 × 30 s stretching intervention, we determined the maximum dorsiflexion range of motion (RoM) with the corresponding fascicle length and pennation angle of the gastrocnemius medialis. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) were measured with a dynamometer. Observation of muscle-tendon junction (MTJ) displacement with ultrasound allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate stiffness. Although RoM increased (static: +4.3%, ballistic: +4.5%, PNF: +3.5%), PRT (static: -11.4%, ballistic: -11.5%, PNF: -13,7%), muscle stiffness (static: -13.1%, ballistic: -20.3%, PNF: -20.2%), and muscle-tendon stiffness (static: -11.3%, ballistic: -10.5%, PNF: -13.7%) decreased significantly in all the stretching groups. Only in the PNF stretching group, the pennation angle in the stretched position (-4.2%) and plantar flexor MVC (-4.6%) decreased significantly. Multivariate analysis showed no clinically relevant difference between the stretching groups. The increase in RoM and the decrease in PRT and muscle-tendon stiffness could be explained by more compliant muscle tissue following a single static, ballistic, or PNF stretching exercise. © 2017 The Authors Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd.

Diagnostics of ballistic electrons in a dc/rf hybrid capacitively coupled discharge

International Nuclear Information System (INIS)

Xu Lin; Chen, Lee; Funk, Merritt; Ranjan, Alok; Hummel, Mike; Bravenec, Ron; Sundararajan, Radha; Economou, Demetre J.; Donnelly, Vincent M.

2008-01-01

The energy distribution of ballistic electrons in a dc/rf hybrid parallel-plate capacitively coupled plasma reactor was measured. Ballistic electrons originated as secondaries produced by ion and electron bombardment of the electrodes. The energy distribution of ballistic electrons peaked at the value of the negative bias applied to the dc electrode. As that bias became more negative, the ballistic electron current on the rf substrate electrode increased dramatically. The ion current on the dc electrode also increased

Towards reliable simulations of ballistic impact on concrete structures

NARCIS (Netherlands)

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

2013-01-01

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

Development and testing of a flexible ballistic neck protection

NARCIS (Netherlands)

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

2016-01-01

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

76 FR 70165 - Ballistic-Resistant Body Armor Standard Workshop

Science.gov (United States)

2011-11-10

... DEPARTMENT OF JUSTICE Office of Justice Programs [OJP (NIJ) Docket No. 1573] Ballistic-Resistant Body Armor Standard Workshop AGENCY: National Institute of Justice, DOJ. ACTION: Notice. SUMMARY: The... jointly hosting a workshop focused on NIJ Standard-0101.06, Ballistic Resistance of Body Armor, and the...

Ballistic transport in nanowire through junctions of narrow–wide–narrow geometry

Energy Technology Data Exchange (ETDEWEB)

Nonoyama, Shinji, E-mail: nonoyama@e.yamagata-u.ac.jp [Faculty of Education, Art, and Science, Yamagata University, Yamagata 990-8560 (Japan); Honma, Yukari [Faculty of Education, Art, and Science, Yamagata University, Yamagata 990-8560 (Japan); Nakamura, Atsunobu [Department of Creative Technology Engineering, National Institute of Technology, Anan College, Anan, Tokushima 774-0017 (Japan)

2015-06-05

We investigate ballistic transport phenomena through a region containing a cavity in a quasi-one-dimensional quantum wire. Conductance curve calculated as a function of a structure parameter shows very narrow periodic dips, which are due to anti-resonances. The nature of the virtual bound state appearing around the cavity is studied in detail. Transport phenomena through a small dilute magnetic semiconductor are also investigated.

Ballistic transport in nanowire through junctions of narrow–wide–narrow geometry

International Nuclear Information System (INIS)

Nonoyama, Shinji; Honma, Yukari; Nakamura, Atsunobu

2015-01-01

We investigate ballistic transport phenomena through a region containing a cavity in a quasi-one-dimensional quantum wire. Conductance curve calculated as a function of a structure parameter shows very narrow periodic dips, which are due to anti-resonances. The nature of the virtual bound state appearing around the cavity is studied in detail. Transport phenomena through a small dilute magnetic semiconductor are also investigated

Trismus in Face Transplantation Following Ballistic Trauma.

Science.gov (United States)

Krezdorn, Nicco; Alhefzi, Muayyad; Perry, Bridget; Aycart, Mario A; Tasigiorgos, Sotirios; Bueno, Ericka M; Green, Jordan R; Pribaz, Julian J; Pomahac, Bohdan; Caterson, Edward J

2018-06-01

Trismus can be a challenging consequence of ballistic trauma to the face, and has rarely been described in the setting of face transplantation. Almost half of all current face transplant recipients in the world received transplantation to restore form and function after a ballistic injury. Here we report our experience and challenges with long standing trismus after face transplantation. We reviewed the medical records of our face transplant recipients whose indication was ballistic injury. We focused our review on trismus and assessed the pre-, peri- and postoperative planning, surgery and functional outcomes. Two patients received partial face transplantation, including the midface for ballistic trauma. Both patients suffered from impaired mouth opening, speech intelligibility, and oral competence. Severe scarring of the temporomandibular joint (TMJ) required intraoperative release in both patients, and additional total condylectomy on the left side 6 months posttransplant for 1 patient. Posttransplant, both patients achieved an improvement in mouth opening; however, there was persistent trismus. One year after transplantation, range of motion of the jaw had improved for both patients. Independent oral food intake was possible 1 year after surgery, although spillage of liquids and mixed consistency solids persisted. Speech intelligibility testing showed impairments in the immediate postoperative period, with improvement to over 85% for both patients at 1 year posttransplant. Ballistic trauma to the face and subsequent reconstructive measures can cause significant scarring and covert injuries to structures such as the TMJ, resulting in long standing trismus. Meticulous individual planning prior to interventions such as face transplantation must take these into account. We encourage intraoperative evaluation of these structures as well as peri- and postoperative treatment when necessary. Due to the nature of the primary injury, functional outcomes after face

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

Science.gov (United States)

Avuthu, Vasudeva Reddy

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

Ballistic One-Dimensional InAs Nanowire Cross-Junction Interconnects.

Science.gov (United States)

Gooth, Johannes; Borg, Mattias; Schmid, Heinz; Schaller, Vanessa; Wirths, Stephan; Moselund, Kirsten; Luisier, Mathieu; Karg, Siegfried; Riel, Heike

2017-04-12

Coherent interconnection of quantum bits remains an ongoing challenge in quantum information technology. Envisioned hardware to achieve this goal is based on semiconductor nanowire (NW) circuits, comprising individual NW devices that are linked through ballistic interconnects. However, maintaining the sensitive ballistic conduction and confinement conditions across NW intersections is a nontrivial problem. Here, we go beyond the characterization of a single NW device and demonstrate ballistic one-dimensional (1D) quantum transport in InAs NW cross-junctions, monolithically integrated on Si. Characteristic 1D conductance plateaus are resolved in field-effect measurements across up to four NW-junctions in series. The 1D ballistic transport and sub-band splitting is preserved for both crossing-directions. We show that the 1D modes of a single injection terminal can be distributed into multiple NW branches. We believe that NW cross-junctions are well-suited as cross-directional communication links for the reliable transfer of quantum information as required for quantum computational systems.

Ballistic hole magnetic microscopy

NARCIS (Netherlands)

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

2005-01-01

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

Efficient thermal diode with ballistic spacer

Science.gov (United States)

Chen, Shunda; Donadio, Davide; Benenti, Giuliano; Casati, Giulio

2018-03-01

Thermal rectification is of importance not only for fundamental physics, but also for potential applications in thermal manipulations and thermal management. However, thermal rectification effect usually decays rapidly with system size. Here, we show that a mass-graded system, with two diffusive leads separated by a ballistic spacer, can exhibit large thermal rectification effect, with the rectification factor independent of system size. The underlying mechanism is explained in terms of the effective size-independent thermal gradient and the match or mismatch of the phonon bands. We also show the robustness of the thermal diode upon variation of the model's parameters. Our finding suggests a promising way for designing realistic efficient thermal diodes.

Japan and Ballistic Missile Defense

National Research Council Canada - National Science Library

Swaine, Michael

2001-01-01

Spurred by a perceived growing ballistic missile threat from within the Asia-Pacific region and requests from the United States to support research and development on components of a missile defense...

Ballistic heat conduction and mass disorder in one dimension

International Nuclear Information System (INIS)

Ong, Zhun-Yong; Zhang, Gang

2014-01-01

It is well-known that in the disordered harmonic chain, heat conduction is subballistic and the thermal conductivity (κ) scales asymptotically as lim L→∞ κ∝L 0.5 where L is the chain length. However, using the nonequilibrium Green's function (NEGF) method and analytical modelling, we show that there exists a critical crossover length scale (L C ) below which ballistic heat conduction (κ∝L) can coexist with mass disorder. This ballistic-to-subballistic heat conduction crossover is connected to the exponential attenuation of the phonon transmittance function Ξ i.e. Ξ(ω, L) = exp[−L/λ(ω)], where λ is the frequency-dependent attenuation length. The crossover length can be determined from the minimum attenuation length, which depends on the maximum transmitted frequency. We numerically determine the dependence of the transmittance on frequency and mass composition as well as derive a closed form estimate, which agrees closely with the numerical results. For the length-dependent thermal conductance, we also derive a closed form expression which agrees closely with numerical results and reproduces the ballistic to subballistic thermal conduction crossover. This allows us to characterize the crossover in terms of changes in the length, mass composition and temperature dependence, and also to determine the conditions under which heat conduction enters the ballistic regime. We describe how the mass composition can be modified to increase ballistic heat conduction. (paper)

Ballistic heat conduction and mass disorder in one dimension.

Science.gov (United States)

Ong, Zhun-Yong; Zhang, Gang

2014-08-20

It is well-known that in the disordered harmonic chain, heat conduction is subballistic and the thermal conductivity (κ) scales asymptotically as lim(L--> ∞) κ ∝ L(0.5) where L is the chain length. However, using the nonequilibrium Green's function (NEGF) method and analytical modelling, we show that there exists a critical crossover length scale (LC) below which ballistic heat conduction (κ ∝ L) can coexist with mass disorder. This ballistic-to-subballistic heat conduction crossover is connected to the exponential attenuation of the phonon transmittance function Ξ i.e. Ξ(ω, L) = exp[-L/λ(ω)], where λ is the frequency-dependent attenuation length. The crossover length can be determined from the minimum attenuation length, which depends on the maximum transmitted frequency. We numerically determine the dependence of the transmittance on frequency and mass composition as well as derive a closed form estimate, which agrees closely with the numerical results. For the length-dependent thermal conductance, we also derive a closed form expression which agrees closely with numerical results and reproduces the ballistic to subballistic thermal conduction crossover. This allows us to characterize the crossover in terms of changes in the length, mass composition and temperature dependence, and also to determine the conditions under which heat conduction enters the ballistic regime. We describe how the mass composition can be modified to increase ballistic heat conduction.

Transition to ballistic regime for heat transport in helium II

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-04

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

Novel formulations of ballistic gelatin. 1. Rheological properties.

Science.gov (United States)

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

2016-06-01

Ballistic gelatin is the simulant of the human body during field tests in forensics and other related fields, due to its physical and mechanical similarities to human trunk and organs. Since the ballistic gelatin used in present has important issues to overcome, an alternative approach is the use of gelatin-polymer composites, where a key factor is the insertion of biocompatible materials, which replicate accurately the human tissues. In order to be able to obtain an improved material in terms of mechanical performances by an easy industrial-scale technology, before the verification of the ballistic parameters by shooting in agreement with military standards, one of the best and cheapest solutions is to perform a thorough check of their rheological properties, in standard conditions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Ballistic Transport Exceeding 28 μm in CVD Grown Graphene.

Science.gov (United States)

Banszerus, Luca; Schmitz, Michael; Engels, Stephan; Goldsche, Matthias; Watanabe, Kenji; Taniguchi, Takashi; Beschoten, Bernd; Stampfer, Christoph

2016-02-10

We report on ballistic transport over more than 28 μm in graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride. The structures are fabricated by an advanced dry van-der-Waals transfer method and exhibit carrier mobilities of up to three million cm(2)/(Vs). The ballistic nature of charge transport is probed by measuring the bend resistance in cross- and square-shaped devices. Temperature-dependent measurements furthermore prove that ballistic transport is maintained exceeding 1 μm up to 200 K.

Simulation of depth of penetration during ballistic impact on thick ...

Indian Academy of Sciences (India)

One-dimensional discrete element model for the ballistic impact is used ... Simulation of ballistic impact process has been done using several ..... MATLAB 7.0 platform is used to simulate impact process using 1-D DEM and to perform the.

Considerations on Dop (Depth Of Penetration) Test for Evaluation of Ceramics Materials Used in Ballistic Protection

Science.gov (United States)

Popa, Ioan-Dan; Dobriţa, Florin

2017-12-01

Tremendous amount of funds and other resorces were invested in studying the response of ceramic materials under ballistic impact, the main goal being to find a way to increase the protection of soldiers and the vehicles used in the modern battlespace. Using of ceramic materials especially carbon based (carbides), nitrogen based (nitrides) and oxygen based (oxides) ceramics in order to increase the protection level of ballistic equipment could be, sometimes, a big challenge when trying to use the proper test in order to evaluate and compare their performances. The role of the tests is to provide a better understanding of their response in different situations and, as a consequence, to make them more efficient as armour components through future improvements. The paper presents shortly the main tests which are used and eventually standardised for evaluating the ballistic behaviour of the ceramics and other armour components, with a special focus to DOP (Depth of Penetration) Tests.

Targeting Low-Energy Ballistic Lunar Transfers

Science.gov (United States)

Parker, Jeffrey S.

2010-01-01

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

A ballistics module as a part of the fire control system

Directory of Open Access Journals (Sweden)

Branka R. Luković

2013-10-01

Full Text Available This article presents a ballistics module as a part of the fire control system of weapons for fire support (mortars, artillery weapons and rocket launchers. The software is "open" with the prominence of autonomy work. It can be modulated and adapted on the user demand. Moreover, it is independent of the hardware base. Introduction: The fire control system is based on a ballistic module (BM which determines the firing data for each weapon tool in the battery. Ballistic calculations, for the given position of the target in relation to the position of tools in the given weather conditions, determine firing data (elevation, direction, timing and locating devices so that the missile seems to cause the desired effect. This paper gives the basic information about the features the BM performs and the manner of their implementation in the fire control system without going into algorithmic solution procedures. Ballistic problem in the fire control system: Ballistic calculation is based on a trajectory calculation of all kinds of projectiles (current, time-fuze, illuminating, smoke, with conventional propulsion, rocket, with built-in gas generator, etc.. Instead of previous solutions, where a trajectory calculation of the fire control system was done by approximate methods, in this BM the trajectory calculation is made by the same model with the same data as for a weapon and ammunition in the process of creating a firing table. The data used in the fire control system are made simultaneously with the preparation of firing tables for a particular tool and associated ammunition,. A modified model of particle, standardized at the NATO level, is also used. Taking into account the meteorological situation, before the trajectory calculation is done, a relative position of the target in relation to the position of the tool should be determined. A selection or loading check is carried out (possibility of reaching a given target as well as the point at which the

Experiments with Liquid Propellant Jet Ignition in a Ballistic Compressor

National Research Council Canada - National Science Library

Birk, Avi

1998-01-01

.... The apparatus consists of an inline ballistic compressor and LP injector. The rebound of the ballistic compressor piston was arrested, trapping 40 to 55 MPa of 750 to 8500 C argon for ignition of circular jets in a windowed test chamber...

Ballistic tongue projection in a miniaturized salamander.

Science.gov (United States)

Deban, Stephen M; Bloom, Segall V

2018-05-20

Miniaturization of body size is often accompanied by peculiarities in morphology that can have functional consequences. We examined the feeding behavior and morphology of the miniaturized plethodontid salamander Thorius, one of the smallest vertebrates, to determine if its performance and biomechanics differ from those of its larger relatives. High-speed imaging and dynamics analysis of feeding at a range of temperatures show that tongue projection in Thorius macdougalli is ballistic and achieves accelerations of up to 600 G with low thermal sensitivity, indicating that tongue projection is powered by an elastic-recoil mechanism. Preceding ballistic projection is an unusual preparatory phase of tongue protrusion, which, like tongue retraction, shows lower performance and higher thermal sensitivity that are indicative of movement being powered directly by muscle shortening. The variability of tongue-projection kinematics and dynamics is comparable to larger ballistic-tongued plethodontids and reveals that Thorius is capable of modulating its tongue movements in response to prey distance. Morphological examination revealed that T. macdougalli possesses a reduced number of myofibers in the tongue muscles, a large projector muscle mass relative to tongue mass, and an unusual folding of the tongue skeleton, compared with larger relatives. Nonetheless, T. macdougalli retains the elaborated collagen aponeuroses in the projector muscle that store elastic energy and a tongue skeleton that is free of direct myofiber insertion, two features that appear to be essential for ballistic tongue projection in salamanders. © 2018 Wiley Periodicals, Inc.

Ballistic study of Tensylon®–based panels

Directory of Open Access Journals (Sweden)

L-C. Alil

2018-06-01

Full Text Available Ballistic protection is a matter of interest requested by civilian as well as military needs. The last decade has witnessed an increase in the use of light weight and efficient armour systems. These panels may be used for body protection as well as light vehicle protection against small calibres or to enhance the protection level of heavier vehicles with decreasing or maintaining their weight penalty. Ultra high molecular weight polyethylene is a material of interest for light weight armour applications. The authors designed panels made of hot–pressed Tensylon® in different configurations with thin steel sheets as a backing and shield protection. Comparison of their ballistic performance to the theory predictions reveals the improved ballistic response of the panels. In addition, a non–pressed Tensylon® panel has been tested in order to facilitate the observations of the failure mechanisms inside the panels. Even if not suitable for practical use, such non–pressed panels clearly reveal the dynamic processes at micro–scale that occur during the impact. The failure mechanisms of the material under bullet penetration are discussed based on photography, optical microscopy and scanning electron microscopy. The supposed effects of the panel pressing are discussed based on the observed difference between pressed and non–pressed structures ballistic response.

19 mm ballistic range: a potpourri of techniques and recipes

International Nuclear Information System (INIS)

Carpluk, G.T.

1975-01-01

The expansion of ballistic gun range facilities at LLL has introduced state-of-the-art diagnostic techniques to glovebox-enclosed ballistic guns systems. These enclosed ballistic ranges are designed for the study of one-dimensional shock phenomena in extremely toxic material such as plutonium. The extension of state-of-the-art phtographic and interferometric diagnostic systems to glovebox-enclosed gun systems introduces new design boundaries and performance criteria on optical and mechanical components. A technique for experimentally evaluating design proposals is illustrated, and several specific examples (such as, target alignment, collateral shrapnel damage, and soft recovery) are discussed

Ballistic behavior of ultra-high molecular weight polyethylene composite: effect of gamma radiation

International Nuclear Information System (INIS)

Alves, Andreia L. dos Santos; Nascimento, Lucio F.C.; Suarez, Joao C. Miguez; lucio2002bol.com.br

2003-01-01

Since World War II, textile composites have been used as ballistic armor. Ultra-high molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials. As they have been developed and commercialized only recently, there is not enough information about the effect of environmental agents in the ballistic performance of UHMWPE composites. In the present work, was evaluated the ballistic behavior of composite plates manufactured with UHMWPE fibers after exposure to gamma radiation. The ballistic tests results were related to the macromolecular alterations induced by the radiation through mechanical (hardness, impact and flexure) and physicochemical (Ftir/Mir. DSC and TGA) testing. It was observed that irradiation induces changes in the UHMWPE, degrading the ballistic performance of the composite. These results are presented and discussed. (author)

Verification of models for ballistic movement time and endpoint variability.

Science.gov (United States)

Lin, Ray F; Drury, Colin G

2013-01-01

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices. This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.

Dynamic knee stability and ballistic knee movement after ACL reconstruction: an application on instep soccer kick.

Science.gov (United States)

Cordeiro, Nuno; Cortes, Nelson; Fernandes, Orlando; Diniz, Ana; Pezarat-Correia, Pedro

2015-04-01

The instep soccer kick is a pre-programmed ballistic movement with a typical agonist-antagonist coordination pattern. The coordination pattern of the kick can provide insight into deficient neuromuscular control. The purpose of this study was to investigate knee kinematics and hamstrings/quadriceps coordination pattern during the knee ballistic extension phase of the instep kick in soccer players after anterior cruciate ligament reconstruction (ACL reconstruction). Seventeen players from the Portuguese Soccer League participated in this study. Eight ACL-reconstructed athletes (experimental group) and 9 healthy individuals (control group) performed three instep kicks. Knee kinematics (flexion and extension angles at football contact and maximum velocity instants) were calculated during the kicks. Rectus femoris (RF), vastus lateralis, vastus medialis, biceps femoralis, and semitendinosus muscle activations were quantified during the knee extension phase. The ACL-reconstructed group had significantly lower knee extension angle (-1.2 ± 1.6, p ballistic control movement pattern between normal and ACL-reconstructed subjects. Performing open kinetic chain exercises using ballistic movements can be beneficial when recovering from ACL reconstruction. The exercises should focus on achieving multi-joint coordination and full knee extension (range of motion). III.

Thermodynamic Bounds on Precision in Ballistic Multiterminal Transport

Science.gov (United States)

Brandner, Kay; Hanazato, Taro; Saito, Keiji

2018-03-01

For classical ballistic transport in a multiterminal geometry, we derive a universal trade-off relation between total dissipation and the precision, at which particles are extracted from individual reservoirs. Remarkably, this bound becomes significantly weaker in the presence of a magnetic field breaking time-reversal symmetry. By working out an explicit model for chiral transport enforced by a strong magnetic field, we show that our bounds are tight. Beyond the classical regime, we find that, in quantum systems far from equilibrium, the correlated exchange of particles makes it possible to exponentially reduce the thermodynamic cost of precision.

Monte Carlo simulation of ballistic transport in high-mobility channels

Energy Technology Data Exchange (ETDEWEB)

Sabatini, G; Marinchio, H; Palermo, C; Varani, L; Daoud, T; Teissier, R [Institut d' Electronique du Sud (CNRS UMR 5214) - Universite Montpellier II (France); Rodilla, H; Gonzalez, T; Mateos, J, E-mail: sabatini@ies.univ-montp2.f [Departamento de Fisica Aplicada - Universidad de Salamanca (Spain)

2009-11-15

By means of Monte Carlo simulations coupled with a two-dimensional Poisson solver, we evaluate directly the possibility to use high mobility materials in ultra fast devices exploiting ballistic transport. To this purpose, we have calculated specific physical quantities such as the transit time, the transit velocity, the free flight time and the mean free path as functions of applied voltage in InAs channels with different lengths, from 2000 nm down to 50 nm. In this way the transition from diffusive to ballistic transport is carefully described. We remark a high value of the mean transit velocity with a maximum of 14x10{sup 5} m/s for a 50 nm-long channel and a transit time shorter than 0.1 ps, corresponding to a cutoff frequency in the terahertz domain. The percentage of ballistic electrons and the number of scatterings as functions of distance are also reported, showing the strong influence of quasi-ballistic transport in the shorter channels.

Monte Carlo simulation of ballistic transport in high-mobility channels

International Nuclear Information System (INIS)

Sabatini, G; Marinchio, H; Palermo, C; Varani, L; Daoud, T; Teissier, R; Rodilla, H; Gonzalez, T; Mateos, J

2009-01-01

By means of Monte Carlo simulations coupled with a two-dimensional Poisson solver, we evaluate directly the possibility to use high mobility materials in ultra fast devices exploiting ballistic transport. To this purpose, we have calculated specific physical quantities such as the transit time, the transit velocity, the free flight time and the mean free path as functions of applied voltage in InAs channels with different lengths, from 2000 nm down to 50 nm. In this way the transition from diffusive to ballistic transport is carefully described. We remark a high value of the mean transit velocity with a maximum of 14x10 5 m/s for a 50 nm-long channel and a transit time shorter than 0.1 ps, corresponding to a cutoff frequency in the terahertz domain. The percentage of ballistic electrons and the number of scatterings as functions of distance are also reported, showing the strong influence of quasi-ballistic transport in the shorter channels.

[Wound Ballistics – a Brief Overview].

Science.gov (United States)

Bolliger, Stephan A; Eggert, Sebastian; Thali, Michael J

2016-02-03

Wound ballistics examines the specific effect, namely the wound profile, of bullets on the body by firing at synthetic models made of ordnance gelatine, glycerin soap and synthetic bones, validated with real cases from (battlefield) surgery and forensic pathology. Wound profile refers to the penetration depth, the bullet deformation/ fragmentation, the diameter of the permanent and the temporary wound cavity. Knowing these features and the used ammunition a surgeon can rapidly assess the amount damage within a patient. The forensic pathologist can draw conclusions as to the used ammunition based on the wound profile. By measuring of the destructive capability of different ammunition types, wound ballistics lays the foundation for guidelines concerning the maximum effect of military ammunition.

One-Dimensional Modelling of Internal Ballistics

Science.gov (United States)

Monreal-González, G.; Otón-Martínez, R. A.; Velasco, F. J. S.; García-Cascáles, J. R.; Ramírez-Fernández, F. J.

2017-10-01

A one-dimensional model is introduced in this paper for problems of internal ballistics involving solid propellant combustion. First, the work presents the physical approach and equations adopted. Closure relationships accounting for the physical phenomena taking place during combustion (interfacial friction, interfacial heat transfer, combustion) are deeply discussed. Secondly, the numerical method proposed is presented. Finally, numerical results provided by this code (UXGun) are compared with results of experimental tests and with the outcome from a well-known zero-dimensional code. The model provides successful results in firing tests of artillery guns, predicting with good accuracy the maximum pressure in the chamber and muzzle velocity what highlights its capabilities as prediction/design tool for internal ballistics.

Comparative study on sintered alumina for ballistic shielding application; Estudo comparativo entre aluminas sinterizadas visando aplicacao em blindagem balistica

Energy Technology Data Exchange (ETDEWEB)

Melo, Francisco Cristovao Lourenco de; Goncalves, Diniz Pereira [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. de Aeronautica e Espaco

1997-12-31

This work presents a development of the armor made from special ceramic materials and kevlar. An experimental investigation was conducted to study the ballistic penetration resistance on three samples taken from sintered alumina: a commercial one and two formulations A and B made in IAE/CTA. The main differences between the two formulations was the grain size and bend resistance. The knowledge of the mechanisms during the penetration and perforation process allowed to apply a ductile composite laminate made form kevlar under the alumina to delay its rupture. The last ballistic test showed how a Weibull`s modulii and other mechanical properties are able to improve ballistic penetration resistance. (author) 3 refs.

Firearms and Ballistics

OpenAIRE

BOLTON-KING, Rachel; Schulze, Johan

2016-01-01

Chapter 7 of the book entitled 'Practical Veterinary Forensics' aims to introduce forensic veterinarians to the scientific concepts underpinning the field of firearms and ballistics. This introduction will enable practitioners to understand wound formation depending on the firearm and ammunition used. \\ud \\ud Various types of firearms, modern firing mechanisms and ammunition will be explained, together with an introduction to the physical concepts underpinning the four main constituents of th...

A new experimental setup to characterize the dynamic mechanical behaviour of ballistic yarns

International Nuclear Information System (INIS)

Chevalier, C; Kerisit, C; Faderl, N; Klavzar, A; Boussu, F; Coutellier, D

2016-01-01

Fabrics have been widely used as part of ballistic protections since the 1970s and the development of new ballistic solutions made from fabrics need numerical simulations, in order to predict the performance of the ballistic protection. The performances and the induced mechanisms in ballistic fabrics during an impact depend on the weaving parameters and also on the inner parameters of the yarns used inside these structures. Thus, knowing the dynamic behaviour of yarn is essential to determine the ballistic behaviour of fabrics during an impact. Two major experimental devices exist and are used to test ballistic yarns in a dynamic uniaxial tension. The first one corresponds to the Split Hopkinson Tensile Bars device, which is commonly used to characterize the mechanical properties of materials in uniaxial tension and under high loading. The second one is the transversal impact device. The real conditions of ballistic impact can be realized with this device. Then, this paper deals with a new experimental setup developed in our laboratory and called the ‘tensile impact test for yarn’ (TITY) device. With this device, specific absorbed energy measurements of para-aramid yarns (336 Tex, Twaron ™ , 1000 filaments) have been carried out and revealed that static and dynamic properties of para-aramid are different. (paper)

Ballistic Impact Response of Woven Hybrid Coir/Kevlar Laminated Composites

Directory of Open Access Journals (Sweden)

Azrin Hani A.R

2016-01-01

Full Text Available The effects of different laminated hybrid composites stacking configuration subjected to ballistic impact were investigated. The hybrid composites consist of woven coir (C and woven Kevlar (K layers laminated together. The samples of woven coir were prepared using handloom device. The composites were produced by stacking the laminated woven coir and Kevlar alternately with the presence of the binder. The samples were tested under ballistic impact with different stacking configuration. The results obtained had successfully achieved the National Institute of Justice (NIJ standard level IIA with energy absorption of 435.6 kJ and 412.2 kJ under the projectile speed of between 330 m/s and 321 m/s respectively. Samples that having Kevlar layer at the front face and woven coir layer as back face achieved partial penetration during projectile impact. This orientation is proven to have good impact energy absorption and able to stop projectile at the second panel of the composites.

Ballistic spin filtering across the ferromagnetic-semiconductor interface

Directory of Open Access Journals (Sweden)

Y.H. Li

2012-03-01

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

Ballistic Resistance of Armored Passenger Vehicles: Test Protocols and Quality Methods

Energy Technology Data Exchange (ETDEWEB)

Jeffrey M. Lacy; Robert E. Polk

2005-07-01

This guide establishes a test methodology for determining the overall ballistic resistance of the passenger compartment of assembled nontactical armored passenger vehicles (APVs). Because ballistic testing of every piece of every component of an armored vehicle is impractical, if not impossible, this guide describes a testing scheme based on statistical sampling of exposed component surface areas. Results from the test of the sampled points are combined to form a test score that reflects the probability of ballistic penetration into the passenger compartment of the vehicle.

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

Directory of Open Access Journals (Sweden)

M. F. Uddin

2009-01-01

Full Text Available We report improving ballistic performance of polyurethane foam by reinforcing it with nanoscale TiO2 particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt% of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nanophased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nanophased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

International Nuclear Information System (INIS)

Uddin, M.F.; Zainuddin, S.; Mahfuz, H.; Jeelani, S.

2009-01-01

We report improving ballistic performance of polyurethane foam by reinforcing it with nano scale TiO 2 particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt % of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs) in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nano phased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nano phased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

Controlling ballistic missiles: How important? How to do it?

International Nuclear Information System (INIS)

Harvey, J.R.; Rubin, U.

1992-01-01

Missiles themselves are not weapons of mass destruction; they do not give states the ability to wreak unimaginable destruction, or to radically shift the balance of power, as nuclear weapons do. Hence, the primary focus of nonproliferation efforts should remain on weapons of mass destruction, particularly nuclear weapons, rather than on one of the many possible means of delivering them. Moreover, as discussed in more detail below, advanced strike aircraft can also be effective in delivering nuclear weapons, and are generally more effective than ballistic missiles for delivering conventional or chemical ordnance. Ultimately, if the industrialized nations seriously desire to control the spread of delivery means for weapons of mass destruction, they need to consider bringing controls over ballistic missiles and advanced strike aircraft more into balance. At the same time, while efforts to control ballistic missile proliferation - centered on the Missile Technology Control Regime (MTCR) - have had some successes and could be strengthened, US policy will be most effective if it recognizes two key realities: the spread of ballistic missiles cannot be as comprehensively controlled as the spread of nuclear weapons, nor need it be as comprehensively controlled

76 FR 14589 - Defense Federal Acquisition Regulation Supplement; Repeal of Restriction on Ballistic Missile...

Science.gov (United States)

2011-03-17

...-AH18 Defense Federal Acquisition Regulation Supplement; Repeal of Restriction on Ballistic Missile...). Section 222 repeals the restriction on purchase of Ballistic Missile Defense research, development, test... Ballistic Missile Defense research, development, test, and evaluation that was required by section 222 of...

Medical Provider Ballistic Protection at Active Shooter Events.

Science.gov (United States)

Stopyra, Jason P; Bozeman, William P; Callaway, David W; Winslow, James; McGinnis, Henderson D; Sempsrott, Justin; Evans-Taylor, Lisa; Alson, Roy L

2016-01-01

There is some controversy about whether ballistic protective equipment (body armor) is required for medical responders who may be called to respond to active shooter mass casualty incidents. In this article, we describe the ongoing evolution of recommendations to optimize medical care to injured victims at such an incident. We propose that body armor is not mandatory for medical responders participating in a rapid-response capacity, in keeping with the Hartford Consensus and Arlington Rescue Task Force models. However, we acknowledge that the development and implementation of these programs may benefit from the availability of such equipment as one component of risk mitigation. Many police agencies regularly retire body armor on a defined time schedule before the end of its effective service life. Coordination with law enforcement may allow such retired body armor to be available to other public safety agencies, such as fire and emergency medical services, providing some degree of ballistic protection to medical responders at little or no cost during the rare mass casualty incident. To provide visual demonstration of this concept, we tested three "retired" ballistic vests with ages ranging from 6 to 27 years. The vests were shot at close range using police-issue 9mm, .40 caliber, .45 caliber, and 12-gauge shotgun rounds. Photographs demonstrate that the vests maintained their ballistic protection and defeated all of these rounds. 2016.

A microscopic model of ballistic-diffusive crossover

International Nuclear Information System (INIS)

Bagchi, Debarshee; Mohanty, P K

2014-01-01

Several low-dimensional systems show a crossover from diffusive to ballistic heat transport when system size is decreased. Although there is some phenomenological understanding of this crossover phenomenon at the coarse-grained level, a microscopic picture that consistently describes both the ballistic and the diffusive transport regimes has been lacking. In this work we derive a scaling form for the thermal current in a class of one dimensional systems attached to heat baths at boundaries and rigorously show that the crossover occurs when the characteristic length scale of the system competes with the system size. (paper)

Influence of Chemical Surface Modification of Woven Fabrics on Ballistic and Stab Protection of Multilayer Packets

Directory of Open Access Journals (Sweden)

Diana GRINEVIČIŪTĖ

2014-06-01

Full Text Available In order to achieve enhanced protective and wear (flexibility, less bulkiness properties of ballistic and stab protecting panels the investigation of chemical surface modification of woven p-aramid fabrics was performed applying different chemical composition shear thickening fluid (STF which improves friction inside fabric structure. For the chemical treatment silicic acid and acrylic dispersion water solutions were used and influence of their different concentrations on panels’ protective properties were investigated. Results of ballistic tests of multilayer protective panel have revealed that shear thickening effect was negligible when shooting at high energy range (E > 440 J. Determination of stab resistance of p-aramid panels has shown that different chemical composition of STFs had different influence on protective properties of the panels. Application of low concentrations of silicic acid determined higher stab resistance values comparing to higher concentrations of acrylic dispersion water solutions. At this stage of research stab tests results as ballistic ones determined that STF application for multilayer p-aramid fabrics protective panels is more efficient at low strike energy levels. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.3138

Star-grain rocket motor - nonsteady internal ballistics

Energy Technology Data Exchange (ETDEWEB)

Loncaric, S.; Greatrix, D.R.; Fawaz, Z. [Ryerson University, Dept. of Aerospace Engineering, Toronto (Canada)

2004-01-01

The nonsteady internal ballistics of a star-grain solid-propellant rocket motor are investigated through a numerical simulation model that incorporates both the internal flow and surrounding structure. The effects of structural vibration on burning rate augmentation and wave development in nonsteady operation are demonstrated. The amount of damping plays a role in influencing the predicted axial combustion instability symptoms of the motor. The variation in oscillation frequencies about a given star grain section periphery, and along the grain with different levels of burn-back, also influences the means by which the local acceleration drives the combustion and flow behaviour. (authors)

Diffusion versus linear ballistic accumulation: different models but the same conclusions about psychological processes?

NARCIS (Netherlands)

Donkin, C.; Brown, S.; Heathcote, A.; Wagenmakers, E.-J.

2011-01-01

Quantitative models for response time and accuracy are increasingly used as tools to draw conclusions about psychological processes. Here we investigate the extent to which these substantive conclusions depend on whether researchers use the Ratcliff diffusion model or the Linear Ballistic

Assessment and monitoring of ballistic and maximal upper-body strength qualities in athletes.

Science.gov (United States)

Young, Kieran P; Haff, G Gregory; Newton, Robert U; Gabbett, Tim J; Sheppard, Jeremy M

2015-03-01

To evaluate whether the dynamic strength index (DSI: ballistic peak force/isometric peak force) could be effectively used to guide specific training interventions and detect training-induced changes in maximal and ballistic strength. Twenty-four elite male athletes were assessed in the isometric bench press and a 45% 1-repetition-maximum (1RM) ballistic bench throw using a force plate and linear position transducer. The DSI was calculated using the peak force values obtained during the ballistic bench throw and isometric bench press. Athletes were then allocated into 2 groups as matched pairs based on their DSI and strength in the 1RM bench press. Over the 5 wk of training, athletes performed either high-load (80-100% 1RM) bench press or moderate-load (40-55% 1RM) ballistic bench throws. The DSI was sensitive to disparate training methods, with the bench-press group increasing isometric bench-press peak force (P=.035, 91% likely), and the ballistic-bench-throw group increasing bench-throw peak force to a greater extent (P≤.001, 83% likely). A significant increase (P≤.001, 93% likely) in the DSI was observed for both groups. The DSI can be used to guide specific training interventions and can detect training-induced changes in isometric bench-press and ballistic bench-throw peak force over periods as short as 5 wk.

Optimization theory for ballistic conversion

NARCIS (Netherlands)

Xie, Yanbo; Versluis, Michel; van den Berg, Albert; Eijkel, Jan C.T.

2016-01-01

The growing demand of renewable energy stimulates the exploration of new materials and methods for clean energy. We recently demonstrated a high efficiency and power density energy conversion mechanism by using jetted charged microdroplets, termed as ballistic energy conversion. Hereby, we model and

The Anti-Ballistic Missile Treaty

International Nuclear Information System (INIS)

Platt, A.

1991-01-01

This paper reports that in late May 1972 former President Richard M. Nixon went to Moscow and signed, among other documents, a Treaty to Limit Anti-Ballistic Missile (ABM) Systems. Under this agreement, both the United States and the Soviet Union made a commitment not to build nationwide ABM defenses against the other's intercontinental and submarine-launched ballistic missiles. They agreed to limit ABM deployments to a maximum of two sites, with no more than 100 launchers per site. Thirteen of the treaty's sixteen articles are intended to prevent any deviation from this. In addition, a joint Standing Consultative Commission to monitor compliance was created. National technical means --- sophisticated monitoring devices on land, sea, and in space --- were to be the primary instruments used to monitor compliance with the treaty. The ABM Treaty was signed in conjunction with an Interim Agreement to Limit Strategic Offensive Arms

Ballistic Rail Gun Soft Recovery Facility

Data.gov (United States)

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

Geometrical optimization of a local ballistic magnetic sensor

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-07

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-09-01

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

Noncontact ballistic motion measurement using a fiber-optic confocal sensor

International Nuclear Information System (INIS)

Shafir, E.; Berkovic, G.; Horovitz, Y.; Appelbaum, G.; Moshe, E.; Horovitz, E.; Skutelski, A.; Werdiger, M.; Perelmutter, L.; Sudai, M.

2007-01-01

A fiber-optic confocal sensor for noncontact ballistic measurements is described. Determination of motion at velocities of 1.7 km/s with an uncertainty as small as ±0.3% is demonstrated for both a projectile and a free-surface target. The fibers detect the passage of the object at their conjugate image points created by low F/ optics. This results in an output signal comprising a train of sharp pulses each precisely identifying when the ballistic object traverses an image point. Since the ballistic object does not contact the sensor at the time of imaging, the measurements do not perturb the motion, enabling multi-fragment measurement, as well as repetitive measurements of the same object point

A simple Boltzmann transport equation for ballistic to diffusive transient heat transport

International Nuclear Information System (INIS)

Maassen, Jesse; Lundstrom, Mark

2015-01-01

Developing simplified, but accurate, theoretical approaches to treat heat transport on all length and time scales is needed to further enable scientific insight and technology innovation. Using a simplified form of the Boltzmann transport equation (BTE), originally developed for electron transport, we demonstrate how ballistic phonon effects and finite-velocity propagation are easily and naturally captured. We show how this approach compares well to the phonon BTE, and readily handles a full phonon dispersion and energy-dependent mean-free-path. This study of transient heat transport shows (i) how fundamental temperature jumps at the contacts depend simply on the ballistic thermal resistance, (ii) that phonon transport at early times approach the ballistic limit in samples of any length, and (iii) perceived reductions in heat conduction, when ballistic effects are present, originate from reductions in temperature gradient. Importantly, this framework can be recast exactly as the Cattaneo and hyperbolic heat equations, and we discuss how the key to capturing ballistic heat effects is to use the correct physical boundary conditions

Ballistic Characterization of the Scalability of Magnesium Alloy AMX602

Science.gov (United States)

2015-07-01

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

Electron eigen-oscillations and ballistic modes of a stable plasma

International Nuclear Information System (INIS)

Jungwirth, K.

1976-01-01

The relation between plasma responses to singular and regular initial perturbations is established. Time scaling is introduced to separate time intervals for which eigen-oscillations (Landau solution) are dominant from such where ballistic modes prevail. The enhanced role is demonstrated of the ballistic modes for an initially perturbed field-free plasma including the phenomenon of plasma wave echoes. (author)

The application of computed tomography in wound ballistics research

International Nuclear Information System (INIS)

Tsiatis, Nick; Moraitis, Konstantinos; Papadodima, Stavroula; Spiliopoulou, Chara; Kelekis, Alexis; Kelesis, Christos; Efstathopoulos, Efstathios; Kordolaimi, Sofia; Ploussi, Agapi

2015-01-01

In wound ballistics research there is a relationship between the data that characterize a bullet and the injury resulted after shooting when it perforates the human body. The bullet path in the human body following skin perforation as well as the damaging effect cannot always be predictable as they depend on various factors such as the bullet's characteristics (velocity, distance, type of firearm and so on) and the tissue types that the bullet passes through. The purpose of this presentation is to highlight the contribution of Computed Tomography (CT) in wound ballistics research. Using CT technology and studying virtual “slices” of specific areas on scanned human bodies, allows the evaluation of density and thickness of the skin, the subcutaneous tissue, the muscles, the vital organs and the bones. Density data taken from Hounsfield units can be converted in g/ml by using the appropriate software. By evaluating the results of this study, the anatomy of the human body utilizing ballistic gel will be reproduced in order to simulate the path that a bullet follows. The biophysical analysis in wound ballistics provides another application of CT technology, which is commonly used for diagnostic and therapeutic purposes in various medical disciplines. (paper)

Ballistic-neutralized chamber transport of intense heavy ion beams

International Nuclear Information System (INIS)

Rose, D.V.; Welch, D.R.; Oliver, B.V.; Clark, R.E.; Sharp, W.M.; Friedman, A.

2001-01-01

Two-dimensional particle-in-cell simulations of intense heavy ion beams propagating in an inertial confinement fusion (ICF) reactor chamber are presented. The ballistic-neutralized transport scheme studied uses 4 GeV Pb +1 ion beams injected into a low-density, gas-filled reactor chamber and the beam is ballistically focused onto an ICF target before entering the chamber. Charge and current neutralization of the beam is provided by the low-density background gas. The ballistic-neutralized simulations include stripping of the beam ions as the beam traverses the chamber as well as ionization of the background plasma. In addition, a series of simulations are presented that explore the charge and current neutralization of the ion beam in an evacuated chamber. For this vacuum transport mode, neutralizing electrons are only drawn from sources near the chamber entrance

Finite Element Based Optimization of Material Parameters for Enhanced Ballistic Protection

Science.gov (United States)

Ramezani, Arash; Huber, Daniel; Rothe, Hendrik

2013-06-01

The threat imposed by terrorist attacks is a major hazard for military installations, vehicles and other items. The large amounts of firearms and projectiles that are available, pose serious threats to military forces and even civilian facilities. An important task for international research and development is to avert danger to life and limb. This work will evaluate the effect of modern armor with numerical simulations. It will also provide a brief overview of ballistic tests in order to offer some basic knowledge of the subject, serving as a basis for the comparison of simulation results. The objective of this work is to develop and improve the modern armor used in the security sector. Numerical simulations should replace the expensive ballistic tests and find vulnerabilities of items and structures. By progressively changing the material parameters, the armor is to be optimized. Using a sensitivity analysis, information regarding decisive variables is yielded and vulnerabilities are easily found and eliminated afterwards. To facilitate the simulation, advanced numerical techniques have been employed in the analyses.

Results of a Round Robin ballistic load sensing headform test series

NARCIS (Netherlands)

Philippens, M.A.G.; Anctil, B.; Markwardt, K.C.

2014-01-01

The majority of methods to assess the behind armour blunt trauma (BABT) risk for ballistic helmets is based on plastic deformable headforms. An alternative, the Ballistic Load Sensing Headform (BLSH) can record the dynamic contact force between helmet back face and the skull. Helmet BABT methods are

Experimental Determination of Ballistic Performance of Composite Material Kevlar 29 and Alumina Powder/ Epoxy by Spherical Projectile

Directory of Open Access Journals (Sweden)

Luay Hashem Abbud

2016-12-01

Full Text Available In this study, a response of hybrid composite laminate woven fiber Kevlar29 – Al2O3 Powder/ Epoxy subjected to high velocity impact loading is presented. The energy absorbed due to impact of small rigid projectile on composite materials targets is determined experimentally. The energy absorbed due to impact of hemispherical projectiles on the developed composite laminates is investigated. The results revealed the maximum ballistic limit at impact velocity is found to be 390.87 ± 6 m/s for an the 18 mm target thickness. The ballistic limit velocity predictions are based on the theoretical method presented from another article. The initial velocity and residual velocity results showed good is agreement compared with the predicted results of Ipson and Recht equations. With 5.4 % of accuracy based on the experimental value for the theoretical model for ballistic limit velocity.

Ballistic superconductivity in semiconductor nanowires

Science.gov (United States)

Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P.; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K.; van Veen, Jasper; de Moor, Michiel W. A.; Bommer, Jouri D. S.; van Woerkom, David J.; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P.A.M.; Quintero-Pérez, Marina; Cassidy, Maja C.; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P.

2017-01-01

Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices. PMID:28681843

Self-diffusion and solute diffusion in alloys under irradiation: Influence of ballistic jumps

International Nuclear Information System (INIS)

Roussel, Jean-Marc; Bellon, Pascal

2002-01-01

We have studied the influence of ballistic jumps on thermal and total diffusion of solvent and solute atoms in dilute fcc alloys under irradiation. For the diffusion components that result from vacancy migration, we introduce generalized five-frequency models, and show that ballistic jumps produce decorrelation effects that have a moderate impact on self-diffusion but that can enhance or suppress solute diffusion by several orders of magnitude. These could lead to new irradiation-induced transformations, especially in the case of subthreshold irradiation conditions. We also show that the mutual influence of thermal and ballistic jumps results in a nonadditivity of partial diffusion coefficients: the total diffusion coefficient under irradiation may be less than the sum of the thermal and ballistic diffusion coefficients. These predictions are confirmed by kinetic Monte Carlo simulations. Finally, it is shown that the method introduced here can be extended to take into account the effect of ballistic jumps on the diffusion of dumbbell interstitials in dilute alloys

Low-temperature ballistic transport in nanoscale epitaxial graphene cross junctions

OpenAIRE

Weingart, S.; Bock, C.; Kunze, U.; Speck, F.; Seyller, Th.; Ley, L.

2009-01-01

We report on the observation of inertial-ballistic transport in nanoscale cross junctions fabricated from epitaxial graphene grown on SiC(0001). Ballistic transport is indicated by a negative bend resistance of R12,43 ~ 170 ohm which is measured in a non-local, four-terminal configuration at 4.2 K and which vanishes as the temperature is increased above 80 K.

Micro-Doppler Feature Extraction and Recognition Based on Netted Radar for Ballistic Targets

Directory of Open Access Journals (Sweden)

Feng Cun-qian

2015-12-01

Full Text Available This study examines the complexities of using netted radar to recognize and resolve ballistic midcourse targets. The application of micro-motion feature extraction to ballistic mid-course targets is analyzed, and the current status of application and research on micro-motion feature recognition is concluded for singlefunction radar networks such as low- and high-resolution imaging radar networks. Advantages and disadvantages of these networks are discussed with respect to target recognition. Hybrid-mode radar networks combine low- and high-resolution imaging radar and provide a specific reference frequency that is the basis for ballistic target recognition. Main research trends are discussed for hybrid-mode networks that apply micromotion feature extraction to ballistic mid-course targets.

Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance-Trained Women.

Science.gov (United States)

Lima, Camila D; Brown, Lee E; Wong, Megan A; Leyva, Whitney D; Pinto, Ronei S; Cadore, Eduardo L; Ruas, Cassio V

2016-11-01

Lima, CD, Brown, LE, Wong, MA, Leyva, WD, Pinto, RS, Cadore, EL, and Ruas, CV. Acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. J Strength Cond Res 30(11): 3220-3227, 2016-Stretching is used to increase joint range of motion, but the acute effects can decrease muscle strength. However, this may depend on the population or mode of stretching. The purpose of this study was to compare the acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. Fifteen resistance-trained women (age 23.8 ± 1.80 years, mass 67.47 ± 7.77 kg, height 168.30 ± 5.53 cm) and 12 ballet dancers (age 22.8 ± 3.04 years, mass 58.67 ± 5.65 kg, height 168.00 ± 7.69 cm) performed 5 days of testing. The first day was control (no stretching), whereas the other 4 days were static or ballistic stretching in a counterbalanced order. Range of motion, strength, and fatigue tests were also performed. Both groups demonstrated a significant decrease in hamstrings strength after static (102.71 ± 2.67 N·m) and ballistic stretching (99.49 ± 2.61 N·m) compared with control (113.059 ± 3.25 N·m), with no changes in quadriceps strength. For fatigue, only ballet dancers demonstrated a decrease from control (71.79 ± 4.88%) to ballistic (65.65 ± 8.19%), but no difference with static (65.01 ± 12.29%). These findings suggest that stretching decreases hamstrings strength similarly in ballet dancers and resistance-trained women, with no differences between modes of stretching. However, ballistic stretching only decreased muscular fatigue in ballet dancers, but not in resistance-trained women. Therefore, no stretching should be performed before strength performance. However, ballistic stretching may decrease acute muscular fatigue in ballet dancers.

Are certain fractures at increased risk for compartment syndrome after civilian ballistic injury?

Science.gov (United States)

Meskey, Thomas; Hardcastle, John; O'Toole, Robert V

2011-11-01

Compartment syndrome after ballistic fracture is uncommon but potentially devastating. Few data are available to help guide clinicians regarding risk factors for developing compartment syndrome after ballistic fractures. Our primary hypothesis was that ballistic fractures of certain bones would be at higher risk for development of compartment syndrome. A retrospective review at a Level I trauma center from 2001 through 2007 yielded 650 patients with 938 fractures resulting from gunshots. We reviewed all operative notes, clinic notes, discharge summaries, and data from our prospective trauma database. Cases in which the attending orthopedic surgeon diagnosed compartment syndrome and performed fasciotomy were considered cases with compartment syndrome. We excluded all prophylactic fasciotomies. Univariate analyses were conducted to identify risk factors associated with development of compartment syndrome. Twenty-six (2.8%) of the 938 fractures were associated with compartment syndrome. Only fibular (11.6%) and tibial (11.4%) fractures had incidence significantly higher than baseline for all ballistic fractures (p Ballistic fractures of the fibula and tibia are at increased risk for development of compartment syndrome over other ballistic fractures. We recommend increased vigilance when treating these injuries, particularly if the fracture is in the proximal aspect of the bone or is associated with vascular injury.

Ballistic Missile Defense

OpenAIRE

Mayer, Michael

2011-01-01

At the 2010 NATO summit in Lisbon, the alliance decided to move forward on the development of a territorial ballistic missile defense (BMD) system and explore avenues for cooperation with Russia in this endeavor. Substantial progress on BMD has been made over the past decade, but some questions remain regarding the ultimate strategic utility of such a system and whether its benefi ts outweigh the possible opportunity costs. Missile defense has been a point of contention between the US and its...

Potentiation Effects of Half-Squats Performed in a Ballistic or Nonballistic Manner.

Science.gov (United States)

Suchomel, Timothy J; Sato, Kimitake; DeWeese, Brad H; Ebben, William P; Stone, Michael H

2016-06-01

This study examined and compared the acute effects of ballistic and nonballistic concentric-only half-squats (COHSs) on squat jump performance. Fifteen resistance-trained men performed a squat jump 2 minutes after a control protocol or 2 COHSs at 90% of their 1 repetition maximum (1RM) COHS performed in a ballistic or nonballistic manner. Jump height (JH), peak power (PP), and allometrically scaled peak power (PPa) were compared using three 3 × 2 repeated-measures analyses of variance. Statistically significant condition × time interaction effects existed for JH (p = 0.037), PP (p = 0.041), and PPa (p = 0.031). Post hoc analysis revealed that the ballistic condition produced statistically greater JH (p = 0.017 and p = 0.036), PP (p = 0.031 and p = 0.026), and PPa (p = 0.024 and p = 0.023) than the control and nonballistic conditions, respectively. Small effect sizes for JH, PP, and PPa existed during the ballistic condition (d = 0.28-0.44), whereas trivial effect sizes existed during the control (d = 0.0-0.18) and nonballistic (d = 0.0-0.17) conditions. Large statistically significant relationships existed between the JH potentiation response and the subject's relative back squat 1RM (r = 0.520; p = 0.047) and relative COHS 1RM (r = 0.569; p = 0.027) during the ballistic condition. In addition, large statistically significant relationship existed between JH potentiation response and the subject's relative back squat strength (r = 0.633; p = 0.011), whereas the moderate relationship with the subject's relative COHS strength trended toward significance (r = 0.483; p = 0.068). Ballistic COHS produced superior potentiation effects compared with COHS performed in a nonballistic manner. Relative strength may contribute to the elicited potentiation response after ballistic and nonballistic COHS.

Application of Super-Hydrophobic Coating for Enhanced Water Repellency of Ballistic Fabric

Energy Technology Data Exchange (ETDEWEB)

Smith, Barton [ORNL; Rajic, Slobodan [ORNL; Hunter, Scott Robert [ORNL

2014-10-01

The objective of this work was to demonstrate that a superhydrophobic coating technology developed at Oak Ridge National Laboratory (ORNL) increases the water repellency of ballistic fabric beyond that provided by existing water repellency treatments. This increased water repellency has the potential to provide durable ballistic fabric for body armor without adding significant weight to the armor or significant manufacturing cost. Specimens of greige and scoured ballistic fabric were treated with a superhydrophobic coating and their weights and degree of water repellency were compared to specimens of untreated fabric. Treatment of both greige and scoured ballistic fabrics yielded highly water repellent fabrics. Our measurements of the water droplet contact angles gave values of approximately 150 , near the lower limit of 160 for superhydrophobic surfaces. The coatings increased the fabric weights by approximately 6%, an amount that is many times less than the estimated weight increase in a conventional treatment of ballistic fabric. The treated fabrics retained a significant amount of water repellency following a basic abrasion test, with water droplet contact angles decreasing by 14 to 23 . Microscopic analysis of the coating applied to woven fabrics indicated that the coating adhered equally well to fibers of greige and scoured yarns. Future evaluation of the superhydrophobic water repellent treatment will involve the manufacture of shoot packs of treated fabric for ballistic testing and provide an analysis of manufacturing scale-up and cost-to-benefit considerations.

Ballistic behaviour of ultra-high molecular weight polyethylene: effect of gamma radiation

International Nuclear Information System (INIS)

Alves, Andreia L.S.; Nascimento, Lucio F.C.; Miguez Suarez, Joao Carlos

2004-01-01

The fiber reinforced polymer matrix composites (PMCs) are considered excellent engineering materials. In structural applications, when a high strength-to-weight ratio is fundamental for the design, PMCs are successfully replacing many conventional materials. Since World War II textile materials have been used as ballistic armor. Materials manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials, for personnel protection and armored vehicles. As these have been developed and commercialized more recently, there is not enough information about the action of the ionizing radiation in the ballistic performance of this armor material. In the present work the ballistic behavior of composite plates manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers were evaluated after exposure to gamma radiation. The ballistic tests results were related to the macromolecular modifications induced by the environmental degradation through mechanical (hardness, impact and flexure) and physicochemical (infrared spectroscopy, differential scanning calorimetry and thermal gravimetric analysis) tests. Our results indicate that gamma irradiation induces modifications in the UHMWPE macromolecular chains, altering the mechanical properties of the composite and decreasing, for higher radiation doses, its ballistic performance. These results are presented and discussed. (author)

Supercurrent and multiple Andreev reflections in micrometer-long ballistic graphene Josephson junctions.

Science.gov (United States)

Zhu, Mengjian; Ben Shalom, Moshe; Mishchsenko, Artem; Fal'ko, Vladimir; Novoselov, Kostya; Geim, Andre

2018-02-08

Ballistic Josephson junctions are predicted to support a number of exotic physics processess, providing an ideal system to inject the supercurrent in the quantum Hall regime. Herein, we demonstrate electrical transport measurements on ballistic superconductor-graphene-superconductor junctions by contacting graphene to niobium with a junction length up to 1.5 μm. Hexagonal boron nitride encapsulation and one-dimensional edge contacts guarantee high-quality graphene Josephson junctions with a mean free path of several micrometers and record-low contact resistance. Transports in normal states including the observation of Fabry-Pérot oscillations and Sharvin resistance conclusively witness the ballistic propagation in the junctions. The critical current density J C is over one order of magnitude larger than that of the previously reported junctions. Away from the charge neutrality point, the I C R N product (I C is the critical current and R N the normal state resistance of junction) is nearly a constant, independent of carrier density n, which agrees well with the theory for ballistic Josephson junctions. Multiple Andreev reflections up to the third order are observed for the first time by measuring the differential resistance in the micrometer-long ballistic graphene Josephson junctions.

Development of high-density ceramic composites for ballistic applications

International Nuclear Information System (INIS)

Rupert, N.L.; Burkins, M.S.; Gooch, W.A.; Walz, M.J.; Levoy, N.F.; Washchilla, E.P.

1993-01-01

The application of ceramic composites for ballistic application has been generally developed with ceramics of low density, between 2.5 and 4.5 g/cm 2 . These materials have offered good performance in defeating small-caliber penetrators, but can suffer time-dependent degradation effects when thicker ceramic tiles are needed to defeat modem, longer, heavy metal penetrators that erode rather than break up. This paper addresses the ongoing development, fabrication procedures, analysis, and ballistic evaluation of thinner, denser ceramics for use in armor applications. Nuclear Metals Incorporated (NMI) developed a process for the manufacture of depleted uranium (DU) ceramics. Samples of the ceramics have been supplied to the US Army Research Laboratory (ARL) as part of an unfunded cooperative study agreement. The fabrication processes used, characterization of the ceramic, and a ballistic comparison between the DU-based ceramic with baseline Al 2 O 3 will be presented

Whither Ballistic Missile Defense?

Science.gov (United States)

1992-11-30

important that technology today is placing enormous power in the many camps-not only information that enables timely decision-making, but also the...WHITHER BALLISTIC MISSILE DEFENSE? BY AMBASSADOR HENRY F. COOPER NOVEMBER 30,1992 TECHNICAL MARKETING SOCIETY OF AMERICA WASHINGTON, DC...Conference on Technical Marketing 2000: Opportunities and Strategies for a Changing World) I intend to discuss the prospects for SDI in a changing

Ballistic model to estimate microsprinkler droplet distribution

Directory of Open Access Journals (Sweden)

Conceição Marco Antônio Fonseca

2003-01-01

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

Ballistic performance of a Kevlar-29 woven fibre composite under varied temperatures

Science.gov (United States)

Soykasap, O.; Colakoglu, M.

2010-05-01

Armours are usually manufactured from polymer matrix composites and used for both military and non-military purposes in different seasons, climates, and regions. The mechanical properties of the composites depend on temperature, which also affects their ballistic characteristics. The armour is used to absorb the kinetic energy of a projectile without any major injury to a person. Therefore, besides a high strength and lightness, a high damping capacity is required to absorb the impact energy transferred by the projectile. The ballistic properties of a Kevlar 29/polyvinyl butyral composite are investigated under varied temperatures in this study. The elastic modulus of the composite is determined from the natural frequency of composite specimens at different temperatures by using a damping monitoring method. Then, the backside deformation of composite plates is analysed experimentally and numerically employing the finite-element program Abaqus. The experimental and numeric results obtained are in good agreement.

Learning without knowing: subliminal visual feedback facilitates ballistic motor learning

DEFF Research Database (Denmark)

Lundbye-Jensen, Jesper; Leukel, Christian; Nielsen, Jens Bo

by subconscious (subliminal) augmented visual feedback on motor performance. To test this, 45 subjects participated in the experiment, which involved learning of a ballistic task. The task was to execute simple ankle plantar flexion movements as quickly as possible within 200 ms and to continuously improve...... by the learner, indeed facilitated ballistic motor learning. This effect likely relates to multiple (conscious versus unconscious) processing of visual feedback and to the specific neural circuitries involved in optimization of ballistic motor performance.......). It is a well- described phenomenon that we may respond to features of our surroundings without being aware of them. It is also a well-known principle, that learning is reinforced by augmented feedback on motor performance. In the present experiment we hypothesized that motor learning may be facilitated...

Ballistic movements of jumping legs implemented as variable components of cricket behaviour.

Science.gov (United States)

Hustert, R; Baldus, M

2010-12-01

Ballistic accelerations of a limb or the whole body require special joint mechanisms in many animals. Specialized joints can be moved by stereotypic or variable motor control during motor patterns with and without ballistic components. As a model of variable motor control, the specialized femur-tibia (knee) joints of cricket (Acheta domesticus) hindlegs were studied during ballistic kicking, jumping and swimming and in non-ballistic walking. In this joint the tendons of the antagonistic flexor and the extensor muscles attach at different distances from the pivot and the opposed lever arms form an angle of 120 deg. A 10:1 ratio of their effective lever arms at full knee flexion helps to prepare for most ballistic extensions: the tension of the extensor can reach its peak while it is restrained by flexor co-contraction. In kicks, preparatory flexion is rapid and the co-contraction terminates just before knee extensions. Therefore, mainly the stored tension of the extensor muscle accelerates the small mass of the tibia. Jumps are prepared with slower extensor-flexor co-contractions that flex both knees simultaneously and then halt to rotate both legs outward to a near horizontal level. From there, catapult extension of both knees accelerates the body, supported by continued high frequency motor activity to their tibia extensor muscles during the ongoing push-off from the substrate. Premature extension of one knee instantly takes load from the lagging leg that extends and catches up, which finally results in a straight jump. In swimming, synchronous ballistic power strokes of both hindlegs drive the tibiae on a ventral-to-posterior trajectory through the water, well coordinated with the swimming patterns of all legs. In walking, running and climbing the steps of the hindlegs range between 45 deg flexion and 125 deg extension and use non-ballistic, alternating activity of knee flexor and extensor muscles. Steep climbing requires longer bursts from the extensor tibiae

Development of Mortar Simulator with Shell-In-Shell System – Problem of External Ballistics

Directory of Open Access Journals (Sweden)

A. Fedaravicius

2007-01-01

Full Text Available The shell-in-shell system used in the mortar simulator raises a number of non-standard technical and computational problems starting from the requirement to distribute the propelling blast energy between the warhead and the ballistic barrel, finishing with the requirement that the length of warhead's flight path must be scaled to combat shell firing tables. The design problem of the simulator is split into two parts – the problem of external ballistics where the initial velocities of the warhead must be determined, and the problem of internal ballistics – where the design of the cartridge and the ballistic barrel must be performed.

Overlapping Ballistic Ejecta Fields: Separating Distinct Blasts at Kings Bowl, Idaho

Science.gov (United States)

Borg, C.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Heldmann, J. L.; Lim, D. S. S.; Haberle, C. W.; Sears, H.; Elphic, R. C.; Kobayashi, L.; Garry, W. B.; Neish, C.; Karunatillake, S.; Button, N.; Purcell, S.; Mallonee, H.; Ostler, B.

2015-12-01

Kings Bowl is a ~2200ka pit crater created by a phreatic blast along a volcanic fissure in the eastern Snake River Plain (ESRP), Idaho. The main crater measures approximately 80m in length, 30m in width, and 30m in depth, with smaller pits located nearby on the Great Rift fissure, and has been targeted by the FINESSE team as a possible analogue for Cyane Fossae, Mars. The phreatic eruption is believed to have occurred due to the interaction of groundwater with lava draining back into the fissure following a lava lake high stand, erupting already solidified basalt from this and previous ERSP lava flows. The contemporaneous draw back of the lava with the explosions may conceal some smaller possible blast pits as more lava drained into the newly formed pits. Ballistic ejecta from the blasts occur on both sides of the fissure. To the east, the ballistic blocks are mantled by fine tephra mixed with eolian dust, the result of a westerly wind during the explosions. We use differential GPS to map the distribution of ballistic blocks on the west side of the fissure, recording position, percent vesiculation, and the length of 3 mutually perpendicular axes for each block >20cm along multiple transects parallel to the fissure. From the several hundred blocks recorded, we have been able to separate the ballistic field into several distinct blast deposits on the basis of size distributions and block concentration. The smaller pits identified from the ballistic fields correspond broadly to the northern and southern limits of the tephra/dust field east of the fissure. Soil formation and bioturbation of the tephra by sagebrush have obliterated any tephrostratigraphy that could have been linked to individual blasts. The ballistic block patterns at Kings Bowl may be used to identify distinct ejecta groups in high-resolution imagery of Mars or other planetary bodies.

BALLISTIC RESISTANT ARTICLES COMPRISING TAPES

NARCIS (Netherlands)

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

2015-01-01

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

Ballistic Imaging and Scattering Measurements for Diesel Spray Combustion: Optical Development and Phenomenological Studies

Science.gov (United States)

2016-04-01

3mm) of diesel sprays from a high-pressure single-hole fuel injector . Ballistic imaging of dodecane and methyl oleate sprays are reported...Porter, Sean P. Duran, Terence E. Parker. Picosecond Ballistic Imaging of Ligament Structures in the Near- Nozzle Region of Diesel Sprays, ILASS...Experiments in Fluids (12 2014) Sean Duran, Jason Porter, Terence Parker. Ballistic Imaging of a Diesel Injector Spray at High Temperature and

77 FR 809 - Request for Proposals for Certification and Testing Expertise for the Ballistic Resistance of...

Science.gov (United States)

2012-01-06

... for Certification and Testing Expertise for the Ballistic Resistance of Personal Body Armor (2008... revising its Ballistic Resistance of Personal Body Armor (2008) Standard and corresponding certification... laboratories with experience in programs for similar types of ballistic-resistant personal protective equipment...

Hazard map for volcanic ballistic impacts at El Chichón volcano (Mexico)

Science.gov (United States)

Alatorre-Ibarguengoitia, Miguel; Ramos-Hernández, Silvia; Jiménez-Aguilar, Julio

2014-05-01

The 1982 eruption of El Chichón Volcano in southeastern Mexico had a strong social and environmental impact. The eruption resulted in the worst volcanic disaster in the recorded history of Mexico, causing about 2,000 casualties, displacing thousands, and producing severe economic losses. Even when some villages were relocated after the 1982 eruption, many people still live and work in the vicinities of the volcano and may be affected in the case of a new eruption. The hazard map of El Chichón volcano (Macías et al., 2008) comprises pyroclastic flows, pyroclastic surges, lahars and ash fall but not ballistic projectiles, which represent an important threat to people, infrastructure and vegetation in the case of an eruption. In fact, the fatalities reported in the first stage of the 1982 eruption were caused by roof collapse induced by ashfall and lithic ballistic projectiles. In this study, a general methodology to delimit the hazard zones for volcanic ballistic projectiles during volcanic eruptions is applied to El Chichón volcano. Different scenarios are defined based on the past activity of the volcano and parameterized by considering the maximum kinetic energy associated with ballistic projectiles ejected during previous eruptions. A ballistic model is used to reconstruct the "launching" kinetic energy of the projectiles observed in the field. The maximum ranges expected for the ballistics in the different explosive scenarios defined for El Chichón volcano are presented in a ballistic hazard map which complements the published hazard map. These maps assist the responsible authorities to plan the definition and mitigation of restricted areas during volcanic crises.

Ballistic resistance of honeycomb sandwich panels under in-plane high-velocity impact.

Science.gov (United States)

Qi, Chang; Yang, Shu; Wang, Dong; Yang, Li-Jun

2013-01-01

The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson's ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs.

Coupling between a Langmuir wave and a ballistic perturbation

International Nuclear Information System (INIS)

Gervais, F.; Olivain, J.; Quemeneur, A.; Trocheris, M.

1980-01-01

The study of the mode-mode coupling usually neglects the ballistic contribution associated with parent waves. If this approximation is not made, a new mode, resulting from the interaction between the ballistic perturbation of pulsation ω 2 associated with one launched wave and the Landau component of pulsation ω 1 of the second one appears if ω 1 >ω 2 . The problem is solved theoretically and experimental evidence of this mode from measurements performed on a D.C. plasma column, confirms the results of this analysis

A Klein-tunneling transistor with ballistic graphene

Energy Technology Data Exchange (ETDEWEB)

Wilmart, Quentin; Fève, Gwendal; Berroir, Jean-Marc; Plaçais, Bernard [Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université P et M Curie, Université D Diderot, 24, rue Lhomond, 75231 Paris Cedex 05 (France); Berrada, Salim; Hung Nguyen, V; Dollfus, Philippe [Institute of Fundamental Electronics, Univ. Paris-Sud, CNRS, Orsay (France); Torrin, David [Département de Physique, Ecole Polytechnique, 91128 Palaiseau (France)

2014-06-15

Today, the availability of high mobility graphene up to room temperature makes ballistic transport in nanodevices achievable. In particular, p-n-p transistors in the ballistic regime give access to Klein tunneling physics and allow the realization of devices exploiting the optics-like behavior of Dirac Fermions (DFs) as in the Veselago lens or the Fabry–Pérot cavity. Here we propose a Klein tunneling transistor based on the geometrical optics of DFs. We consider the case of a prismatic active region delimited by a triangular gate, where total internal reflection may occur, which leads to the tunable suppression of transistor transmission. We calculate the transmission and the current by means of scattering theory and the finite bias properties using non-equilibrium Green's function (NEGF) simulation. (letter)

Spin-orbit-coupling induced torque in ballistic domain walls: Equivalence of charge-pumping and nonequilibrium magnetization formalisms

NARCIS (Netherlands)

Yuan, Z.; Kelly, Paul J.

2016-01-01

To study the effect of spin-orbit coupling (SOC) on spin-transfer torque in magnetic materials, we have implemented two theoretical formalisms that can accommodate SOC. Using the “charge-pumping” formalism, we find two contributions to the out-of-plane spin-transfer torque parameter β in ballistic

Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress

Science.gov (United States)

2016-04-05

Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress Ronald O’Rourke Specialist in Naval...Affairs April 5, 2016 Congressional Research Service 7-5700 www.crs.gov R41129 Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine...1,091.1 million in research and development funding for the Ohio replacement program (ORP), a program to design and build a new class of 12 ballistic

Optimization theory for ballistic energy conversion

NARCIS (Netherlands)

Xie, Yanbo; Versluis, Michel; Van Den Berg, Albert; Eijkel, Jan C.T.

2016-01-01

The growing demand of renewable energy stimulates the exploration of new materials and methods for clean energy. We recently demonstrated a high efficiency and power density energy conversion mechanism by using jetted charged microdroplets, termed as ballistic energy conversion. Hereby, we model and

Electron Interference in Ballistic Graphene Nanoconstrictions

DEFF Research Database (Denmark)

Baringhaus, Jens; Settnes, Mikkel; Aprojanz, Johannes

2016-01-01

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

Transition from normal to ballistic diffusion in a one-dimensional impact system

Science.gov (United States)

Livorati, André L. P.; Kroetz, Tiago; Dettmann, Carl P.; Caldas, Iberê L.; Leonel, Edson D.

2018-03-01

We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity. Through statistical and numerical analysis of the velocity of the particle, we are able to characterize a transition between the two regimes, where transport properties were used to characterize the scenario of the ballistic regime. Also, in an analysis of the probability of an orbit to reach an accelerator mode as a function of the velocity, we observe a competition between the normal and ballistic transport in the midrange velocity.

The use of gelatine in wound ballistics research.

Science.gov (United States)

Carr, D J; Stevenson, T; Mahoney, P F

2018-04-25

Blocks of gelatine are used in both lethality and survivability studies for broadly the same reason, i.e. comparison of ammunition effects using a material that it is assumed represents (some part of) the human body. The gelatine is used to visualise the temporary and permanent wound profiles; elements of which are recognised as providing a reasonable approximation to wounding in humans. One set of researchers aim to improve the lethality of the projectile, and the other to understand the effects of the projectile on the body to improve survivability. Research areas that use gelatine blocks are diverse and include ammunition designers, the medical and forensics communities and designers of ballistic protective equipment (including body armour). This paper aims to provide an overarching review of the use of gelatine for wound ballistics studies; it is not intended to provide an extensive review of wound ballistics as that already exists, e.g. Legal Med 23:21-29, 2016. Key messages are that test variables, projectile type (bullet, fragmentation), impact site on the body and intermediate layers (e.g. clothing, personal protective equipment (PPE)) can affect the resulting wound profiles.

Precession feature extraction of ballistic missile warhead with high velocity

Science.gov (United States)

Sun, Huixia

2018-04-01

This paper establishes the precession model of ballistic missile warhead, and derives the formulas of micro-Doppler frequency induced by the target with precession. In order to obtain micro-Doppler feature of ballistic missile warhead with precession, micro-Doppler bandwidth estimation algorithm, which avoids velocity compensation, is presented based on high-resolution time-frequency transform. The results of computer simulations confirm the effectiveness of the proposed method even with low signal-to-noise ratio.

Low-Energy Ballistic Transfers to Lunar Halo Orbits

Science.gov (United States)

Parker, Jeffrey S.

2009-01-01

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

Statistics of magnetoconductance in ballistic cavities

International Nuclear Information System (INIS)

Yang, X.; Ishio, H.; Burgdoerfer, J.

1995-01-01

The statistical properties of magnetoconductance in ballistic microcavities are investigated numerically. The distribution of conductance for chaotic cavities is found to follow the renormalized Porter-Thomas distribution suggested by random-matrix theory for the Gaussian ensemble while the conductance distribution of regular cavities in magnetic fields is nonuniversal and shifted towards the maximum value for a given number of open channels. The renormalized Porter-Thomas distribution implies a universal dependence of fluctuation amplitude on the mean conductance for chaotic cavities in the absence of time-reversal symmetry. The fluctuation amplitude for regular cavities is found to be larger than the saturation value of the fluctuation amplitude of chaotic cavities predicted by random-matrix theory. The change of the mean conductance as a function of the external magnetic field is consistent with semiclassical predictions

Ballistic near-field heat transport in dense many-body systems

Science.gov (United States)

Latella, Ivan; Biehs, Svend-Age; Messina, Riccardo; Rodriguez, Alejandro W.; Ben-Abdallah, Philippe

2018-01-01

Radiative heat transport mediated by near-field interactions is known to be superdiffusive in dilute, many-body systems. Here we use a generalized Landauer theory of radiative heat transfer in many-body planar systems to demonstrate a nonmonotonic transition from superdiffusive to ballistic transport in dense systems. We show that such a transition is associated to a change of the polarization of dominant modes. Our findings are complemented by a quantitative study of the relaxation dynamics of the system in the different regimes of heat transport. This result could have important consequences on thermal management at nanoscale of many-body systems.

Feasibility of ballistic strength training in sub-acute stroke: A randomized, controlled, assessor-blinded pilot study.

Science.gov (United States)

Hendrey, Genevieve; Clark, Ross A; Holland, Anne E; Mentiplay, Benjamin F; Davis, Carly; Windfeld-Lund, Cristie; Raymond, Melissa J; Williams, Gavin

2018-05-30

To establish the feasibility and effectiveness of a six week ballistic strength training protocol in people with stroke. Randomized, controlled, assessor-blinded study. Sub-acute inpatient rehabilitation. Consecutively admitted inpatients with a primary diagnosis of first ever stroke with lower limb weakness, functional ambulation category score of ≥3, and ability to walk ≥14m were screened for eligibility to recruit 30 participants for randomization. Participants were randomized to standard therapy or ballistic strength training three times per week for six weeks. The primary aim was to evaluate feasibility and outcomes included recruitment rate, participant retention and attrition, feasibility of the exercise protocol, therapist burden and participant safety. Secondary outcomes included measures of mobility, lower limb muscle strength, muscle power and quality of life. Thirty participants (11% of those screened) with mean age of 50 (SD 18) years were randomized. The median number of sessions attended was 15/18 and 17/18 for the ballistic and control groups respectively. Earlier than expected discharge home (n=4) and illness (n=7) were the most common reasons for non-attendance. Participants performed the exercises safely, with no study-related adverse events. There were significant (pballistic group for comfortable gait velocity (mean difference (MD) 0.31m/s, 95% confidence interval CI: 0.08 to 0.52), muscle power, as measured by peak jump height (MD 8cm, 95% CI: 3 to 13) and peak propulsive velocity (MD 64cm/s, 95% CI: 17 to 112). Ballistic training was safe and feasible in select ambulant people with stroke. Similar rates of retention and attrition suggest that ballistic training was acceptable to patients. Secondary outcomes provide promising results that warrant further investigation in a larger trial. Copyright © 2018. Published by Elsevier Inc.

3D topography measurements on correlation cells—a new approach to forensic ballistics identifications

International Nuclear Information System (INIS)

Song, John; Chu, Wei; Tong, Mingsi; Soons, Johannes

2014-01-01

Based on three-dimensional (3D) topography measurements on correlation cells, the National Institute of Standards and Technology (NIST) has developed the ‘NIST Ballistics Identification System (NBIS)’ aimed at accurate ballistics identifications and fast ballistics evidence searches. The 3D topographies are divided into arrays of correlation cells to identify ‘valid correlation areas’ and eliminate ‘invalid correlation areas’ from the matching and identification procedure. A ‘congruent matching cells’ (CMC)’ method using three types of identification parameters of the paired correlation cells (cross correlation function maximum CCF max , spatial registration position in x–y and registration angle θ) is used for high accuracy ballistics identifications. ‘Synchronous processing’ is proposed for correlating multiple cell pairs at the same time to increase the correlation speed. The proposed NBIS can be used for correlations of both geometrical topographies and optical intensity images. All the correlation parameters and algorithms are in the public domain and subject to open tests. An error rate reporting procedure has been developed that can greatly add to the scientific support for the firearm and toolmark identification specialty, and give confidence to the trier of fact in court proceedings. The NBIS is engineered to employ transparent identification parameters and criteria, statistical models and correlation algorithms. In this way, interoperability between different ballistics identification systems can be more easily achieved. This interoperability will make the NBIS suitable for ballistics identifications and evidence searches with large national databases, such as the National Integrated Ballistic Information Network in the United States. (paper)

Effect of joint design on ballistic performance of quenched and tempered steel welded joints

International Nuclear Information System (INIS)

Balakrishnan, M.; Balasubramanian, V.; Madhusudhan Reddy, G.

2014-01-01

Highlights: • Traditional usage of austenitic stainless steel filler for armour steel welding shows poor ballistic performance. • Earlier efforts show dubious success on ballistic resistance of armour steel joints. • Comparative evaluation of equal/unequal joint design on ballistic performance. • Effect of joint design covers the main aspects of successful bullet stoppage. - Abstract: A study was carried out to evaluate the effect of joint design on ballistic performance of armour grade quenched and tempered steel welded joints. Equal double Vee and unequal double Vee joint configuration were considered in this study. Targets were fabricated using 4 mm thick tungsten carbide hardfaced middle layer; above and below which austenitic stainless steel layers were deposited on both sides of the hardfaced interlayer in both joint configurations. Shielded metal arc welding process was used to deposit for all layers. The fabricated targets were evaluated for its ballistic performance and the results were compared in terms of depth of penetration on weld metal. From the ballistic test results, it was observed that both the targets successfully stopped the bullet penetration at weld center line. Of the two targets, the target made with unequal double Vee joint configuration offered maximum resistance to the bullet penetration at weld metal location without any bulge at the rear side. The higher volume of austenitic stainless steel front layer and the presence of hardfaced interlayer after some depth of soft austenitic stainless steel front layer is the primary reason for the superior ballistic performance of this joint

3D topography measurements on correlation cells—a new approach to forensic ballistics identifications

Science.gov (United States)

Song, John; Chu, Wei; Tong, Mingsi; Soons, Johannes

2014-06-01

Based on three-dimensional (3D) topography measurements on correlation cells, the National Institute of Standards and Technology (NIST) has developed the ‘NIST Ballistics Identification System (NBIS)’ aimed at accurate ballistics identifications and fast ballistics evidence searches. The 3D topographies are divided into arrays of correlation cells to identify ‘valid correlation areas’ and eliminate ‘invalid correlation areas’ from the matching and identification procedure. A ‘congruent matching cells’ (CMC)’ method using three types of identification parameters of the paired correlation cells (cross correlation function maximum CCFmax, spatial registration position in x-y and registration angle θ) is used for high accuracy ballistics identifications. ‘Synchronous processing’ is proposed for correlating multiple cell pairs at the same time to increase the correlation speed. The proposed NBIS can be used for correlations of both geometrical topographies and optical intensity images. All the correlation parameters and algorithms are in the public domain and subject to open tests. An error rate reporting procedure has been developed that can greatly add to the scientific support for the firearm and toolmark identification specialty, and give confidence to the trier of fact in court proceedings. The NBIS is engineered to employ transparent identification parameters and criteria, statistical models and correlation algorithms. In this way, interoperability between different ballistics identification systems can be more easily achieved. This interoperability will make the NBIS suitable for ballistics identifications and evidence searches with large national databases, such as the National Integrated Ballistic Information Network in the United States.

Schottky barrier height measurements of Cu/Si(001), Ag/Si(001), and Au/Si(001) interfaces utilizing ballistic electron emission microscopy and ballistic hole emission microscopy

International Nuclear Information System (INIS)

Balsano, Robert; Matsubayashi, Akitomo; LaBella, Vincent P.

2013-01-01

The Schottky barrier heights of both n and p doped Cu/Si(001), Ag/Si(001), and Au/Si(001) diodes were measured using ballistic electron emission microscopy and ballistic hole emission microscopy (BHEM), respectively. Measurements using both forward and reverse ballistic electron emission microscopy (BEEM) and (BHEM) injection conditions were performed. The Schottky barrier heights were found by fitting to a linearization of the power law form of the Bell-Kaiser BEEM model. The sum of the n-type and p-type barrier heights are in good agreement with the band gap of silicon and independent of the metal utilized. The Schottky barrier heights are found to be below the region of best fit for the power law form of the BK model, demonstrating its region of validity

Investigation of Basalt Woven Fabrics for Military Applications

Science.gov (United States)

2011-11-01

investigates the use of basalt fibers in a composite along with SC-15 epoxy resin for ballistic protection. Basalt fibers are not known as a ballistic...material but rather as a structural one. Even though basalt fibers are not expected to outperform some of the higher ballistic performing materials...such as the aramid and polyethylene fibers ; however, due to the lower manufacturing costs, basalt fibers are an interesting alternative. The objective

Ballistic Missile Defense and ABM Treaty Limitations

National Research Council Canada - National Science Library

Robinson, Brian

1998-01-01

The U.S. must critically evaluate our current ballistic missile defense (BMD) strategy. In today's geostrategic context, is it sound strategy to continue to impose 1972 ABM Treaty restrictions on BMD systems development...

The usage of optical fibers for damage detection in ballistic protection composite laminates

Directory of Open Access Journals (Sweden)

Živković Irena D.

2006-01-01

Full Text Available This paper describes the procedure of embedding fiber optic sensors in laminar thermoplastic composite material, as well as damage investigation after ballistic loading. Thermoplastic-reinforced composite materials were made for increased material damage resistance during ballistic loading. Damage inside the composite material was detected by observing the intensity drop of the light signal transmitted through the optical fibers. Experimental testing was carried out in order to observe and analyze the response of the material under various load conditions. Different types of Kevlar reinforced composite materials (thermoplastic, thermo reactive and thermoplastic with ceramic plate as the impact face were made. Material damage resistance during ballistic loading was investigated and compared. Specimens were tested under multiple load conditions. The opto-electronic part of the measurement system consists of two light-emitting diodes as light sources for the optical fibers, and two photo detectors for the light intensity measurement. The output signal was acquired from photo detectors by means of a data acquisition board and personal computer. The measurements showed an intensity drop of the transmitted light signal as a result of the applied loading on composite structure for all the optical fibers. All the diagrams show similar behavior of the light signal intensity. In fact, all of them may be divided into three zones: the zone of penetration of the first composite layer, the bullet traveling zone through the composite material till its final stop, and the material relaxation zone. The attenuation of the light signal intensity during impact is caused by the influence of the applied dynamic stress on the embedded optical fibers. The applied stress caused micro bending of the optical fiber, changes in the shape of the cross-section and the unequal changes of the indices of refraction of the core and cladding due to the stress-optic effect. The

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

Directory of Open Access Journals (Sweden)

Davide Viganò

2016-01-01

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

Herontwerp Ballistisch vest voor Vrouwen: Fase 1 (Redesign Ballistic Vest for Women: Phase 1)

National Research Council Canada - National Science Library

Koerhuis, C. L; Weghorst, M. G

2008-01-01

.... A questionnaire was filled out by fourteen female soldiers consisting of questions about complaints, characteristics of the ballistic vest and the mobility of the combat soldier wearing the ballistic vest...

A Klein-tunneling transistor with ballistic graphene

International Nuclear Information System (INIS)

Wilmart, Quentin; Fève, Gwendal; Berroir, Jean-Marc; Plaçais, Bernard; Berrada, Salim; Hung Nguyen, V; Dollfus, Philippe; Torrin, David

2014-01-01

Today, the availability of high mobility graphene up to room temperature makes ballistic transport in nanodevices achievable. In particular, p-n-p transistors in the ballistic regime give access to Klein tunneling physics and allow the realization of devices exploiting the optics-like behavior of Dirac Fermions (DFs) as in the Veselago lens or the Fabry–Pérot cavity. Here we propose a Klein tunneling transistor based on the geometrical optics of DFs. We consider the case of a prismatic active region delimited by a triangular gate, where total internal reflection may occur, which leads to the tunable suppression of transistor transmission. We calculate the transmission and the current by means of scattering theory and the finite bias properties using non-equilibrium Green's function (NEGF) simulation. (letter)

Wound ballistic evaluation of the Taser® XREP ammunition.

Science.gov (United States)

Kunz, Sebastian N; Adamec, Jiri; Zinka, Bettina; Münzel, Daniela; Noël, Peter B; Eichner, Simon; Manthei, Axel; Grove, Nico; Graw, M; Peschel, Oliver

2013-01-01

The Taser® eXtended Range Electronic Projectile (XREP®) is a wireless conducted electrical weapon (CEW) designed to incapacitate a person from a larger distance. The aim of this study was to analyze the ballistic injury potential of the XREP. Twenty rounds were fired from the Taser®X12 TM shotgun into ballistic soap covered with artificial skin and clothing at different shooting distances (1-25 m). One shot was fired at pig skin at a shooting distance of 10 m. The average projectile velocity was 67.0 m/s. The kinetic energy levels on impact varied from 28-52 J. Depending on the intermediate target, the projectiles penetrated up to 4.2 cm into the ballistic soap. On impact the nose assembly did not separate from the chassis, and no electrical activation was registered. Upon impact, a skin penetration of the XREP cannot be excluded. However, it is very unlikely at shooting distances of 10 m or more. Clothing and a high elasticity limit of the target body area can significantly reduce the penetration risk on impact.

Performance of Lead-Free versus Lead-Based Hunting Ammunition in Ballistic Soap

Science.gov (United States)

Gremse, Felix; Krone, Oliver; Thamm, Mirko; Kiessling, Fabian; Tolba, René Hany; Rieger, Siegfried; Gremse, Carl

2014-01-01

Background Lead-free hunting bullets are an alternative to lead-containing bullets which cause health risks for humans and endangered scavenging raptors through lead ingestion. However, doubts concerning the effectiveness of lead-free hunting bullets hinder the wide-spread acceptance in the hunting and wildlife management community. Methods We performed terminal ballistic experiments under standardized conditions with ballistic soap as surrogate for game animal tissue to characterize dimensionally stable, partially fragmenting, and deforming lead-free bullets and one commonly used lead-containing bullet. The permanent cavities created in soap blocks are used as a measure for the potential wound damage. The soap blocks were imaged using computed tomography to assess the volume and shape of the cavity and the number of fragments. Shots were performed at different impact speeds, covering a realistic shooting range. Using 3D image segmentation, cavity volume, metal fragment count, deflection angle, and depth of maximum damage were determined. Shots were repeated to investigate the reproducibility of ballistic soap experiments. Results All bullets showed an increasing cavity volume with increasing deposited energy. The dimensionally stable and fragmenting lead-free bullets achieved a constant conversion ratio while the deforming copper and lead-containing bullets showed a ratio, which increases linearly with the total deposited energy. The lead-containing bullet created hundreds of fragments and significantly more fragments than the lead-free bullets. The deflection angle was significantly higher for the dimensionally stable bullet due to its tumbling behavior and was similarly low for the other bullets. The deforming bullets achieved higher reproducibility than the fragmenting and dimensionally stable bullets. Conclusion The deforming lead-free bullet closely resembled the deforming lead-containing bullet in terms of energy conversion, deflection angle, cavity shape

Performance of lead-free versus lead-based hunting ammunition in ballistic soap.

Directory of Open Access Journals (Sweden)

Felix Gremse

Full Text Available BACKGROUND: Lead-free hunting bullets are an alternative to lead-containing bullets which cause health risks for humans and endangered scavenging raptors through lead ingestion. However, doubts concerning the effectiveness of lead-free hunting bullets hinder the wide-spread acceptance in the hunting and wildlife management community. METHODS: We performed terminal ballistic experiments under standardized conditions with ballistic soap as surrogate for game animal tissue to characterize dimensionally stable, partially fragmenting, and deforming lead-free bullets and one commonly used lead-containing bullet. The permanent cavities created in soap blocks are used as a measure for the potential wound damage. The soap blocks were imaged using computed tomography to assess the volume and shape of the cavity and the number of fragments. Shots were performed at different impact speeds, covering a realistic shooting range. Using 3D image segmentation, cavity volume, metal fragment count, deflection angle, and depth of maximum damage were determined. Shots were repeated to investigate the reproducibility of ballistic soap experiments. RESULTS: All bullets showed an increasing cavity volume with increasing deposited energy. The dimensionally stable and fragmenting lead-free bullets achieved a constant conversion ratio while the deforming copper and lead-containing bullets showed a ratio, which increases linearly with the total deposited energy. The lead-containing bullet created hundreds of fragments and significantly more fragments than the lead-free bullets. The deflection angle was significantly higher for the dimensionally stable bullet due to its tumbling behavior and was similarly low for the other bullets. The deforming bullets achieved higher reproducibility than the fragmenting and dimensionally stable bullets. CONCLUSION: The deforming lead-free bullet closely resembled the deforming lead-containing bullet in terms of energy conversion

Variability of Plyometric and Ballistic Exercise Technique Maintains Jump Performance.

Science.gov (United States)

Chandler, Phillip T; Greig, Matthew; Comfort, Paul; McMahon, John J

2018-06-01

Chandler, PT, Greig, M, Comfort, P, and McMahon, JJ. Variability of plyometric and ballistic exercise technique maintains jump performance. J Strength Cond Res 32(6): 1571-1582, 2018-The aim of this study was to investigate changes in vertical jump technique over the course of a training session. Twelve plyometric and ballistic exercise-trained male athletes (age = 23.4 ± 4.6 years, body mass = 78.7 ± 18.8 kg, height = 177.1 ± 9.0 cm) performed 3 sets of 10 repetitions of drop jump (DJ), rebound jump (RJ) and squat jump (SJ). Each exercise was analyzed from touchdown to peak joint flexion and peak joint flexion to take-off. Squat jump was analyzed from peak joint flexion to take-off only. Jump height, flexion and extension time and range of motion, and instantaneous angles of the ankle, knee, and hip joints were measured. Separate 1-way repeated analyses of variance compared vertical jump technique across exercise sets and repetitions. Exercise set analysis found that SJ had lower results than DJ and RJ for the angle at peak joint flexion for the hip, knee, and ankle joints and take-off angle of the hip joint. Exercise repetition analysis found that the ankle joint had variable differences for the angle at take-off, flexion, and extension time for RJ. The knee joint had variable differences for flexion time for DJ and angle at take-off and touchdown for RJ. There was no difference in jump height. Variation in measured parameters across repetitions highlights variable technique across plyometric and ballistic exercises. This did not affect jump performance, but likely maintained jump performance by overcoming constraints (e.g., level of rate coding).

Hybrid carbon-glass fiber/toughened epoxy thick composites subject to drop-weight and ballistic impacts

Science.gov (United States)

Sevkat, Ercan

The goals of this study are to investigate the low velocity and ballistic impact response of thick-section hybrid fiber composites at room temperature. Plain-woven S2-Glass and IM7 Graphite fabrics are chosen as fiber materials reinforcing the SC-79 epoxy. Four different types of composites consisting of alternating layers of glass and graphite woven fabric sheets are considered. Tensile tests are conducted using 98 KN (22 kip) MTS testing machine equipped with environmental chamber. Low-velocity impact tests are conducted using an Instron-Dynatup 8250 impact test machine equipped with an environmental chamber. Ballistic impact tests are performed using helium pressured high-speed gas-gun. Tensile tests results were used to define the material behavior of the hybrid and non-hybrid composites in Finite Element modeling. The low velocity and ballistic impact tests showed that hybrid composites performance was somewhere between non-hybrid woven composites. Using woven glass fabrics as outer skin improved the impact performance of woven graphite composite. However hybrid composites are prone to delamination especially between dissimilar layers. The ballistic limit velocity V50 hybrid composites were higher that of woven graphite composite and lower than that of woven glass composite. Both destructive cross-sectional micrographs and nondestructive ultrasonic techniques are used to evaluate the damage created by impact. The Finite Element code LS-DYNA is chosen to perform numerical simulations of low velocity and ballistic impact on thick-section hybrid composites. The damage progression in these composites shows anisotropic nonlinearity. The material model to describe this behavior is not available in LS-DYNA material library. Initially, linear orthotropic material with damage (Chan-Chan Model) is employed to simulate some of the experimental results. Then, user-defined material subroutine is incorporated into LS-DYNA to simulate the nonlinear behavior. The

Combined Structural and Compositional Evolution of Planetary Rings Due to Micrometeoroid Impacts and Ballistic Transport

Science.gov (United States)

Estrada, Paul R.; Durisen, Richard H.; Cuzzi, Jeffrey N.; Morgan, Demitri A.

2015-01-01

We introduce improved numerical techniques for simulating the structural and compositional evolution of planetary rings due to micrometeoroid bombardment and subsequent ballistic transport of impact ejecta. Our current, robust code is capable of modeling structural changes and pollution transport simultaneously over long times on both local and global scales. In this paper, we describe the methodology based on the original structural code of Durisen et al. (1989, Icarus 80, 136-166) and on the pollution transport code of Cuzzi and Estrada (1998, Icarus 132, 1-35). We provide demonstrative simulations to compare with, and extend upon previous work, as well as examples of how ballistic transport can maintain the observed structure in Saturn's rings using available Cassini occultation optical depth data. In particular, we explicitly verify the claim that the inner B (and presumably A) ring edge can be maintained over long periods of time due to an ejecta distribution that is heavily biased in the prograde direction through a balance between the sharpening effects of ballistic transport and the broadening effects of viscosity. We also see that a "ramp"-like feature forms over time just inside that edge. However, it does not remain linear for the duration of the runs presented here unless a less steep ejecta velocity distribution is adopted. We also model the C ring plateaus and find that their outer edges can be maintained at their observed sharpness for long periods due to ballistic transport. We hypothesize that the addition of a significant component of a retrograde-biased ejecta distribution may help explain the linearity of the ramp and is probably essential for maintaining the sharpness of C ring plateau inner edges. This component would arise for the subset of micrometeoroid impacts which are destructive rather than merely cratering. Such a distribution will be introduced in future work.

Voltage quantization by ballistic vortices in two-dimensional superconductors

International Nuclear Information System (INIS)

Orlando, T.P.; Delin, K.A.

1991-01-01

The voltage generated by moving ballistic vortices with a mass m ν in a two-dimensional superconducting ring is quantized, and this quantization depends on the amount of charge enclosed by the ring. The quantization of the voltage is the dual to flux quantization in a superconductor, and is a manifestation of the Aharonov-Casher effect. The quantization is obtained by applying the Bohr-Sommerfeld criterion to the canonical momentum of the ballistic vortices. The results of this quantization condition can also be used to understand the persistent voltage predicted by van Wees for an array of Josephson junctions

Ballistic Phonon Penetration Depth in Amorphous Silicon Dioxide.

Science.gov (United States)

Yang, Lin; Zhang, Qian; Cui, Zhiguang; Gerboth, Matthew; Zhao, Yang; Xu, Terry T; Walker, D Greg; Li, Deyu

2017-12-13

Thermal transport in amorphous silicon dioxide (a-SiO 2 ) is traditionally treated as random walks of vibrations owing to its greatly disordered structure, which results in a mean free path (MFP) approximately the same as the interatomic distance. However, this picture has been debated constantly and in view of the ubiquitous existence of thin a-SiO 2 layers in nanoelectronic devices, it is imperative to better understand this issue for precise thermal management of electronic devices. Different from the commonly used cross-plane measurement approaches, here we report on a study that explores the in-plane thermal conductivity of double silicon nanoribbons with a layer of a-SiO 2 sandwiched in-between. Through comparing the thermal conductivity of the double ribbon samples with that of corresponding single ribbons, we show that thermal phonons can ballistically penetrate through a-SiO 2 of up to 5 nm thick even at room temperature. Comprehensive examination of double ribbon samples with various oxide layer thicknesses and van der Waals bonding strengths allows for extraction of the average ballistic phonon penetration depth in a-SiO 2 . With solid experimental data demonstrating ballistic phonon transport through a-SiO 2 , this work should provide important insight into thermal management of electronic devices.

Ballistic calculation of nonequilibrium Green's function in nanoscale devices using finite element method

International Nuclear Information System (INIS)

Kurniawan, O; Bai, P; Li, E

2009-01-01

A ballistic calculation of a full quantum mechanical system is presented to study 2D nanoscale devices. The simulation uses the nonequilibrium Green's function (NEGF) approach to calculate the transport properties of the devices. While most available software uses the finite difference discretization technique, our work opts to formulate the NEGF calculation using the finite element method (FEM). In calculating a ballistic device, the FEM gives some advantages. In the FEM, the floating boundary condition for ballistic devices is satisfied naturally. This paper gives a detailed finite element formulation of the NEGF calculation applied to a double-gate MOSFET device with a channel length of 10 nm and a body thickness of 3 nm. The potential, electron density, Fermi functions integrated over the transverse energy, local density of states and the transmission coefficient of the device have been studied. We found that the transmission coefficient is significantly affected by the top of the barrier between the source and the channel, which in turn depends on the gate control. This supports the claim that ballistic devices can be modelled by the transport properties at the top of the barrier. Hence, the full quantum mechanical calculation presented here confirms the theory of ballistic transport in nanoscale devices.

What Should Be the United States Policy towards Ballistic Missile Defense for Northeast Asia?

National Research Council Canada - National Science Library

Delgado, Roberto L

2005-01-01

.... The threat of ballistic missiles from Northeast Asia is especially high. China and North Korea are seen as the top threats in the region when it comes to the delivery of WMD through ballistic missiles...

Impulse-variability theory: implications for ballistic, multijoint motor skill performance.

Science.gov (United States)

Urbin, M A; Stodden, David F; Fischman, Mark G; Weimar, Wendi H

2011-01-01

Impulse-variability theory (R. A. Schmidt, H. N. Zelaznik, B. Hawkins, J. S. Frank, & J. T. Quinn, 1979) accounts for the curvilinear relationship between the magnitude and resulting variability of the muscular forces that influence the success of goal-directed limb movements. The historical roots of impulse-variability theory are reviewed in the 1st part of this article, including the relationship between movement speed and spatial error. The authors then address the relevance of impulse-variability theory for the control of ballistic, multijoint skills, such as throwing, striking, and kicking. These types of skills provide a stark contrast to the relatively simple, minimal degrees of freedom movements that characterized early research. However, the inherent demand for ballistic force generation is a strong parallel between these simple laboratory tasks and multijoint motor skills. Therefore, the authors conclude by recommending experimental procedures for evaluating the adequacy of impulse variability as a theoretical model within the context of ballistic, multijoint motor skill performance. Copyright © Taylor & Francis Group, LLC

Effects of equal channel angular extrusion on microstructure, strength and ballistic performance of AA5754 plates

DEFF Research Database (Denmark)

Mishin, Oleg; Hong, Chuanshi; Toftegaard, Helmuth Langmaack

2014-01-01

The microstructure, hardness, tensile properties and ballistic performance have been investigated in thick plates of the AA5754 alloy both in a coarse-grained as-received condition and after 4 passes of equal channel angular extrusion (ECAE) conducted at elevated temperatures. It is found that ECAE...

High Resolution, High-Speed Photography, an Increasingly Prominent Diagnostic in Ballistic Research Experiments

International Nuclear Information System (INIS)

Shaw, L.; Muelder, S.

1999-01-01

High resolution, high-speed photography is becoming a prominent diagnostic in ballistic experimentation. The development of high speed cameras utilizing electro-optics and the use of lasers for illumination now provide the capability to routinely obtain high quality photographic records of ballistic style experiments. The purpose of this presentation is to review in a visual manner the progress of this technology and how it has impacted ballistic experimentation. Within the framework of development at LLNL, we look at the recent history of large format high-speed photography, and present a number of photographic records that represent the state of the art at the time they were made. These records are primarily from experiments involving shaped charges. We also present some examples of current photographic technology, developed within the ballistic community, that has application to hydro diagnostic experimentation at large. This paper is designed primarily as an oral-visual presentation. This written portion is to provide general background, a few examples, and a bibliography

Force-velocity properties' contribution to bilateral deficit during ballistic push-off.

Science.gov (United States)

Samozino, Pierre; Rejc, Enrico; di Prampero, Pietro Enrico; Belli, Alain; Morin, Jean-Benoît

2014-01-01

The objective of this study is to quantify the contribution of the force-velocity (F-v) properties to bilateral force deficit (BLD) in ballistic lower limb push-off and to relate it to individual F-v mechanical properties of the lower limbs. The F-v relation was individually assessed from mechanical measurements for 14 subjects during maximal ballistic lower limb push-offs; its contribution to BLD was then investigated using a theoretical macroscopic approach, considering both the mechanical constraints of movement dynamics and the maximal external capabilities of the lower limb neuromuscular system. During ballistic lower limb push-off, the maximum force each lower limb can produce was lower during bilateral than unilateral actions, thus leading to a BLD of 36.7% ± 5.7%. The decrease in force due to the F-v mechanical properties amounted to 19.9% ± 3.6% of the force developed during BL push-offs, which represents a nonneural contribution to BLD of 43.5% ± 9.1%. This contribution to BLD that cannot be attributed to changes in neural features was negatively correlated to the maximum unloaded extension velocity of the lower limb (r = -0.977, P push-off, BLD is due to both neural alterations and F-v mechanical properties, the latter being associated with the change in movement velocity between bilateral and unilateral actions. The level of the contribution of the F-v properties depends on the individual F-v mechanical profile of the entire lower limb neuromuscular system: the more the F-v profile is oriented toward velocity capabilities, the lower the loss of force from unilateral to bilateral push-offs due to changes in movement velocity.

Ballistic Electron Emission Microscopy/Spectroscopy on Au/Titanylphthalocyanine/GaAs Heterostructures

International Nuclear Information System (INIS)

Oezcan, S; Roch, T; Strasser, G; Smoliner, J; Franke, R; Fritz, T

2007-01-01

In this article Au/titanylphthalocyanine/GaAs diodes incorporating ultra smooth thin films of the archetypal organic semiconductor titanylphthalocyanine (TiOPc) were investigated by Ballistic Electron Emission Microscopy/Spectroscopy (BEEM/S). Analyzing the BEEM spectra, we find that the TiOPc increases the BEEM threshold voltage compared to reference Au/GaAs diodes. From BEEM images taken we conclude that our molecular beam epitaxial (MBE) grown samples show very homogeneous transmission, compare to wet chemically manufactured organic films. The barrier height measured on the Au- TiOPc-GaAs is V b ∼ 1.2eV, which is in good agreement with the data found in [T. Nishi, K. Tanai, Y. Cuchi, M. R. Willis, and K. Seki Chem. Phys. Lett., vol. 414, pp. 479-482, 2005.]. The results indicate that TiOPc functions as a p-type semiconductor, which is plausible since the measurements were carried out in air [K. Walzer, T. Toccoli, A. Pallaori, R. Verucchi, T. Fritz, K. Leo, A. Boschetti, and S. Iannotte Surf. Scie., vol. 573, pp. 346-358, 2004

Influence of ballistic bench press on upper body power output in professional rugby players.

Science.gov (United States)

West, Daniel J; Cunningham, Daniel J; Crewther, Blair T; Cook, Christian J; Kilduff, Liam P

2013-08-01

The use of heavy resistance exercise provides an effective preload stimulus for inducing postactivation potentiation (PAP) and increasing peak power output (PPO). However, this approach has limited application in many sporting situations (e.g., incorporation in a precompetition warm-up); and therefore, more practical strategies for inducing PAP need to be investigated. The aim of the present study was to compare the PPO changes after performing a preload stimulus of either a ballistic exercise or a traditional heavy resistance exercise. Twenty professional rugby union players completed 3 testing sessions, each separated by 48 hours. On the first occasion, subjects underwent a 3 repetition maximum (3RM)-bench press testing session. On the next 2 occasions, subjects performed a ballistic bench throw at baseline (30% of 1RM), followed by a preload stimulus of either heavy resistance training (HRT) (heavy bench press: 3 sets of 3 repetitions at 87% 1RM) or BBP (3 sets of 3 repetitions at 30% on 1RM) followed by ballistic bench throw after 8 minutes recovery. The trials were randomized and counterbalanced. Both preload stimuli protocols increased PPO compared with baseline (BBP baseline 892 ± 108 vs. 8 minutes 924 ± 119 W, p < 0.001; HRT baseline 893 ± 104 vs. 8 minutes 931 ± 116 W; p < 0.001). There were no conditional differences between PPO at 8 minutes (p = 0.141); moreover, the change in PPO from baseline was also similar between conditions (BBP Δ + 33 ± 18; HRT Δ + 38 ± 21 W; p = 0.112). In conclusion, a ballistic exercise provided an effective method of inducing PAP and increasing upper-body PPO; moreover, this elicited similar increases in PPO as a traditional heavy resistance exercise preloading stimulus.

Self-Consistent Theory of Shot Noise Suppression in Ballistic Conductors

Science.gov (United States)

Bulashenko, O. M.; Rubí, J. M.; Kochelap, V. A.

Shot-noise measurements become a fundamental tool to probe carrier interactions in mesoscopic systems [1]. A matter of particular interest is the significance of Coulomb interaction which may keep nearby electrons more regularly spaced rather than strictly at random and lead to the noise reduction. That effect occurs in different physical situations. Among them are charge-limited ballistic transport, resonant tunneling, single-electron tunneling, etc. In this communication we address the problem of Coulomb correlations in ballistic conductors under the space-charge-limited transport conditions, and present for the first time a semiclassical self-consistent theory of shot noise in these conductors by solving analytically the kinetic equation coupled self-consistently with a Poisson equation. Basing upon this theory, exact results for current noise in a two-terminal ballistic conductor under the action of long-range Coulomb correlations has been derived. The noise reduction factor (in respect to the uncorrelated value) is obtained in a closed analytical form for a full range of biases ranging from thermal to shot-noise limits which describe perfectly the results of the Monte Carlo simulations for a nondegenerate electron gas [2]. The magnitude of the noise reduction exceeds 0.01, which is of interest from the point of view of possible applications. Using these analytical results one may estimate a relative contribution to the noise from different groups of carriers (in energy space and/or real space) and to investigate in great detail the correlations between different groups of carriers. This leads us to suggest an electron energy spectroscopy experiment to probe the Coulomb correlations in ballistic conductors. Indeed, while the injected carriers are uncorrelated, those in the volume of the conductor are strongly correlated, as follows from the derived formulas for the fluctuation of the distribution function. Those correlations may be observed experimentally by

Natural Mallow Fiber-Reinforced Epoxy Composite for Ballistic Armor Against Class III-A Ammunition

Science.gov (United States)

Nascimento, Lucio Fabio Cassiano; Holanda, Luane Isquerdo Ferreira; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Gomes, Alaelson Vieira; Lima, Édio Pereira

2017-10-01

Epoxy matrix composites reinforced with up to 30 vol pct of continuous and aligned natural mallow fibers were for the first time ballistic tested as personal armor against class III-A 9 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared to those in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout and rupture as well as epoxy cracking. As compared to Kevlar™, the mallow fiber composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes the mallow fiber composites a promising material for personal ballistic protection.

Comparison of third-order plasma wave echoes with ballistic second-order plasma wave echoes

International Nuclear Information System (INIS)

Leppert, H.D.; Schuelter, H.; Wiesemann, K.

1982-01-01

The apparent dispersion of third-order plasma wave echoes observed in a high frequency plasma is compared with that of simultaneously observed ballistic second-order echoes. Amplitude and wavelength of third-order echoes are found to be always smaller than those of second-order echoes, however, the dispersion curves of both types of echoes are very similar. These observations are in qualitative agreement with calculations of special ballistic third-order echoes. The ballistic nature of the observed third-order echoes may, therefore, be concluded from these measurements. (author)

Comparison of ballistic impact effects between biological tissue and gelatin.

Science.gov (United States)

Jin, Yongxi; Mai, Ruimin; Wu, Cheng; Han, Ruiguo; Li, Bingcang

2018-02-01

Gelatin is commonly used in ballistic testing as substitute for biological tissue. Comparison of ballistic impact effects produced in the gelatin and living tissue is lacking. The work in this paper was aimed to compare the typical ballistic impact effects (penetration trajectory, energy transfer, temporary cavity) caused by 4.8mm steel ball penetrating the 60kg porcine hind limbs and 10wt% gelatin. The impact event in the biological tissue was recorded by high speed flash X-ray machine at different delay time, while the event in the gelatin continuously recorded by high speed video was compared to that in the biological tissue. The collected results clearly displayed that the ballistic impact effects in the muscle and gelatin were similar for the steel ball test; as for instance, the projectile trajectory in the two targets was basically similar, the process of energy transfer was highly coincident, and the expansion of temporary cavity followed the same pattern. This study fully demonstrated that choosing gelatin as muscle simulant was reasonable. However, the maximum temporary cavity diameter in the gelatin was a little larger than that in the muscle, and the expansion period of temporary cavity was longer in the gelatin. Additionally, the temporary cavity collapse process in the two targets followed different patterns, and the collapse period in the gelatin was two times as long as that in the muscle. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stochastic processes crossing from ballistic to fractional diffusion with memory: exact results

Directory of Open Access Journals (Sweden)

V. Ilyin

2010-01-01

Full Text Available We address the now classical problem of a diffusion process that crosses over from a ballistic behavior at short times to a fractional diffusion (sub- or super-diffusion at longer times. Using the standard non-Markovian diffusion equation we demonstrate how to choose the memory kernel to exactly respect the two different asymptotics of the diffusion process. Having done so we solve for the probability distribution function as a continuous function which evolves inside a ballistically expanding domain. This general solution agrees for long times with the probability distribution function obtained within the continuous random walk approach but it is much superior to this solution at shorter times where the effect of the ballistic regime is crucial.

Effect of ageing on the calibration of ballistic gelatin.

Science.gov (United States)

Guey, Jason; Rodrigues, S; Pullen, A; Shaw, B; Kieser, D C

2018-02-27

Ballistic gelatin is commonly used as a validated surrogate for soft tissue during terminal ballistic testing. However, the effect of a delay between production and testing of a gelatin mould remains unknown. The aim of this study was to determine any potential effects of ageing on ballistic gelatin. Depth of penetration (DoP) of 4.5 mm spherical fragment simulating projectiles was ascertained using mixtures of 10%, 11.25% and 20% Type A 250 Bloom ballistic gelatin. Testing was performed daily for 5 days using velocities between 75 and 210 m/s. DoP at day 5 was statistically compared with day 1, and net mass change was recorded daily. No significant difference was found for DoP observed with time in any of the samples (P>0.05). Spearman correlation was excellent in all moulds. The moulds with known standard calibrations remained in calibration throughout the study period. Mass loss of less than 1% was noted in all samples. Mass loss was the only quantifiable measure of changes in the blocks with time, but did not correlate with any changes in DoP. This may provide reassurance when undertaking such testing that an inadvertent delay will not significantly alter the penetration properties of the mould. Future research is recommended to determine any potential effect on the mechanical properties of gelatin at higher velocity impacts and whether the calibration corresponds to an adequate simulation under such conditions. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Valley-symmetric quasi-1D transport in ballistic graphene

Science.gov (United States)

Lee, Hu-Jong

We present our recent studies on gate-defined valley-symmetric one-dimensional (1D) carrier guiding in ballistic monolayer graphene and valley-symmetry-protected topological 1D transport in ballistic bilayer graphene. Successful carrier guiding was realized in ballistic monolayer graphene even in the absence of a band gap by inducing a high distinction ( more than two orders of magnitude) in the carrier density between the region of a quasi-1D channel and the rest of the top-gated regions. Conductance of a channel shows quantized values in units of 4e2/ h, suggesting that the valley symmetry is preserved. For the latter, the topological 1D conduction was realized between two closely arranged insulating regions with inverted band gaps, induced under a pair of split dual gating with polarities opposite to each other. The maximum conductance along the boundary channel showed 4e2/ h, again with the preserved valley symmetry. The 1D topological carrier guiding demonstrated in this study affords a promising route to robust valleytronic applications and sophisticated valley-associated functionalities based on 2D materials. This work was funded by the National Research Foundation of Korea.

Ballistic Performance of Porous-Ceramic, Thermal-Protection-Systems

Science.gov (United States)

Christiansen, E. L.; Davis, B. A.; Miller, J. E.; Bohl, W. E.; Foreman, C. D.

2009-01-01

Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Space Shuttle and are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s, and the findings of the influence of material equation-of-state on the simulation of the impact event to characterize the ballistic performance of these materials. These results will be compared with heritage models1 for these materials developed from testing at lower velocities. Assessments of predicted spacecraft risk based upon these tests and simulations will also be discussed.

Deterrence of ballistic missile systems and their effects on today's air operations

Science.gov (United States)

Durak, Hasan

2015-05-01

Lately, the effect-based approach has gained importance in executing air operations. Thus, it makes more successful in obtaining the desired results by breaking the enemy's determination in a short time. Air force is the first option to be chosen in order to defuse the strategic targets. However, the problems such as the defense of targets and country, radars, range…etc. becoming serious problems. At this level ballistic missiles emerge as a strategic weapon. Ultimate emerging technologies guided by the INS and GPS can also be embedded with multiple warheads and reinforced with conventional explosive, ballistic missiles are weapons that can destroy targets with precision. They have the advantage of high speed, being easily launched from every platform and not being easily detected by air defense systems contrary to other air platforms. While these are the advantages, there are also disadvantages of the ballistic missiles. The high cost, unavailability of nuclear, biological and chemical weapons, and its limited effect while using conventional explosives against destroying the fortified targets are the disadvantages. The features mentioned above should be considered as limitation to the impact of the ballistic missiles. The aim is to impose the requests on enemies without starting a war with all components and to ensure better implementation of the operation functions during the air operations. In this study, effects of ballistic missiles in the future on air battle theatre will be discussed in the beginning, during the process and at the end phase of air operations within the scope of an effect-based approach.

Localization and Ballistic Diffusion for the Tempered Fractional Brownian-Langevin Motion

Science.gov (United States)

Chen, Yao; Wang, Xudong; Deng, Weihua

2017-10-01

This paper discusses the tempered fractional Brownian motion (tfBm), its ergodicity, and the derivation of the corresponding Fokker-Planck equation. Then we introduce the generalized Langevin equation with the tempered fractional Gaussian noise for a free particle, called tempered fractional Langevin equation (tfLe). While the tfBm displays localization diffusion for the long time limit and for the short time its mean squared displacement (MSD) has the asymptotic form t^{2H}, we show that the asymptotic form of the MSD of the tfLe transits from t^2 (ballistic diffusion for short time) to t^{2-2H}, and then to t^2 (again ballistic diffusion for long time). On the other hand, the overdamped tfLe has the transition of the diffusion type from t^{2-2H} to t^2 (ballistic diffusion). The tfLe with harmonic potential is also considered.

Ballistic Application of Coir Fiber Reinforced Epoxy Composite in Multilayered Armor

OpenAIRE

Luz, Fernanda Santos da; Monteiro, Sergio Neves; Lima, Eduardo Sousa; Lima Júnior, Édio Pereira

2017-01-01

Multilayered armor systems (MAS) composed of relatively lighter materials with capacity to provide personal ballistic protection are being extensively investigated and used in armor vests. A typical MAS to stand high impact energy 7.62 mm bullet has a front ceramic followed by an aramid fabric laminate, such as Kevlar™. Since both the army and municipal police personnel might need to wear an armor vest, a large number of vests needs to be supplied. In the case of Kevlar™, one of the most expe...

Characterization of dynamic properties of ballistic clay

NARCIS (Netherlands)

Carton, E.P.; Roebroeks, G.H.J.J.; Broos, J.P.F.; Halls, V.; Zheng, J.

2014-01-01

In order use material models in (numerical) calculations, the mechanical properties of all materials involved should be known. At TNO an indirect method to determine the dynamic flow stress of materials has been generated by a combination of ballistic penetration tests with an energy-based

Influence of Material Properties on the Ballistic Performance of Ceramics for Personal Body Armour

Directory of Open Access Journals (Sweden)

Christian Kaufmann

2003-01-01

Full Text Available In support of improved personal armour development, depth of penetration tests have been conducted on four different ceramic materials including alumina, modified alumina, silicon carbide and boron carbide. These experiments consisted of impacting ceramic tiles bonded to aluminum cylinders with 0.50 caliber armour piercing projectiles. The results are presented in terms of ballistic efficiency, and the validity of using ballistic efficiency as a measure of ceramic performance was examined. In addition, the correlation between ballistic performance and ceramic material properties, such as elastic modulus, hardness, spall strength and Hugoniot Elastic Limit, has been considered.

Ballistic Impact Resistance of Plain Woven Kenaf/Aramid Reinforced Polyvinyl Butyral Laminated Hybrid Composite

Directory of Open Access Journals (Sweden)

Suhad D. Salman

2016-07-01

Full Text Available Traditionally, the helmet shell has been used to provide protection against head injuries and fatalities caused by ballistic threats. In this study, because of the high cost of aramid fibres and the necessity for environmentally friendly alternatives, a portion of aramid was replaced with plain woven kenaf fibre, with different arrangements and thicknesses, without jeopardising the requirements demanded by U.S. Army helmet specifications. Furthermore, novel helmets were produced and tested to reduce the dependency on the ballistic resistance components. Their use could lead to helmets that are less costly and more easily available than conventional helmet armour. The hybrid materials subjected to ballistic tests were composed of 19 layers and were fabricated by the hot press technique using different numbers and configurations of plain woven kenaf and aramid layers. In the case of ballistic performance tests, a positive effect was found for the hybridisation of kenaf and aramid laminated composites.

Ballistic target tracking algorithm based on improved particle filtering

Science.gov (United States)

Ning, Xiao-lei; Chen, Zhan-qi; Li, Xiao-yang

2015-10-01

Tracking ballistic re-entry target is a typical nonlinear filtering problem. In order to track the ballistic re-entry target in the nonlinear and non-Gaussian complex environment, a novel chaos map particle filter (CMPF) is used to estimate the target state. CMPF has better performance in application to estimate the state and parameter of nonlinear and non-Gassuian system. The Monte Carlo simulation results show that, this method can effectively solve particle degeneracy and particle impoverishment problem by improving the efficiency of particle sampling to obtain the better particles to part in estimation. Meanwhile CMPF can improve the state estimation precision and convergence velocity compared with EKF, UKF and the ordinary particle filter.

48 CFR 252.225-7018 - Notice of prohibition of certain contracts with foreign entities for the conduct of ballistic...

Science.gov (United States)

2010-10-01

... certain contracts with foreign entities for the conduct of ballistic missile defense research, development... foreign entities for the conduct of ballistic missile defense research, development, test, and evaluation... With Foreign Entities for the Conduct of Ballistic Missile Defense Research, Development, Test, and...

[Ballistic concepts and management of gunshot wounds at members].

Science.gov (United States)

Fabeck, L; Hock, N; Goffin, J; Ngatchou, W

2017-01-01

Ballistic trauma is not the prerogative of battlefields and currently extends to civil environments. Any surgeon or emergency room can be faced with such trauma whose management requires an understanding of wound ballistics. The aim of this retrospective is reviewing the management of ballistic trauma within the C.H.U. Saint-Pierre hospital over a period of ten years. Data recorded included demographics data, lesions, clinical parameters, imaging, treatment and outcome. It appears that the wounds of the members have a low mortality rate but a significant rate of complications. Patients should be managed according to the ATLS protocol and according hemodynamic stability and location of the injury, benefit from imaging. Unstable patients will be operated in emergency, stable patients will be treated according to the extent of damage and the type of fracture either conservatively or by external fixator and intramedullary centromedullary. Debridement and antibiotics are recommended as a nerve exploration if there is a peripheral paralysis. The management of trauma in our sample appear not optimal in light of the literature especially in terms of setting the vascular point of debridement, antibiotic and nerve repair resulting in significant consequences. Two management protocols according to patients' hemodynamic status are offered.

A School Experiment in Kinematics: Shooting from a Ballistic Cart

Science.gov (United States)

Kranjc, T.; Razpet, N.

2011-10-01

Many physics textbooks start with kinematics. In the lab, students observe the motions, describe and make predictions, and get acquainted with basic kinematics quantities and their meaning. Then they can perform calculations and compare the results with experimental findings. In this paper we describe an experiment that is not often done, but is interesting and attractive to students—the ballistic cart, i.e., the shooting of a ball from a cart moving along a slope. For that, one has to be familiar with one-dimensional uniform motion and one-dimensional motion with constant acceleration, as well as curvilinear motion that is a combination of such motions.1,2 The experimental results confirm theoretical predictions.

Ballistic transport in semiconductor nanostructures: From quasi ...

Indian Academy of Sciences (India)

By suitable design it is possible to achieve quasi-ballistic transport in semiconductor nanostructures over times up to the ps-range. Monte-Carlo simulations reveal that under these conditions phase-coherent real-space oscillations of an electron ensemble, generated by fs-pulses become possible in wide potential wells.

A theoretical analysis of ballistic electron emission microscopy: band structure effects and attenuation lengths

International Nuclear Information System (INIS)

Andres, P.L. de; Reuter, K.; Garcia-Vidal, F.J.; Flores, F.; Hohenester, U.; Kocevar, P.

1998-01-01

Using quantum mechanical approach, we compute the ballistic electron emission microscopy current distribution in reciprocal space to compare experimental and theoretical spectroscopic I(V) curves. In the elastic limit, this formalism is a 'parameter free' representation of the problem. At low voltages, low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experiments (ballistic conditions). At low temperatures, inelastic effects can be taken into account approximately by introducing an effective electron-electron lifetime as an imaginary part in the energy. Ensemble Monte Carlo calculations were also performed to obtain ballistic electron emission microscopy currents in good agreement with the previous approach. (author)

Analysis of behind the armor ballistic trauma.

Science.gov (United States)

Wen, Yaoke; Xu, Cheng; Wang, Shu; Batra, R C

2015-05-01

The impact response of body armor composed of a ceramic plate with an ultrahigh molecular weight polyethylene (UHMWPE) fiber-reinforced composite and layers of UHMWPE fibers shielding a block of ballistic gelatin has been experimentally and numerically analyzed. It is a surrogate model for studying injuries to human torso caused by a bullet striking body protection armor placed on a person. Photographs taken with a high speed camera are used to determine deformations of the armor and the gelatin. The maximum depth of the temporary cavity formed in the ballistic gelatin and the peak pressure 40mm behind the center of the gelatin front face contacting the armor are found to be, respectively, ~34mm and ~15MPa. The Johnson-Holmquist material model has been used to simulate deformations and failure of the ceramic. The UHMWPE fiber-reinforced composite and the UHMWPE fiber layers are modeled as linear elastic orthotropic materials. The gelatin is modeled as a strain-rate dependent hyperelastic material. Values of material parameters are taken from the open literature. The computed evolution of the temporary cavity formed in the gelatin is found to qualitatively agree with that seen in experiments. Furthermore, the computed time histories of the average pressure at four points in the gelatin agree with the corresponding experimentally measured ones. The maximum pressure at a point and the depth of the temporary cavity formed in the gelatin can be taken as measures of the severity of the bodily injury caused by the impact; e.g. see the United States National Institute of Justice standard 0101.06-Ballistic Resistance of Body Armor. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ballistic Josephson junctions based on CVD graphene

Science.gov (United States)

Li, Tianyi; Gallop, John; Hao, Ling; Romans, Edward

2018-04-01

Josephson junctions with graphene as the weak link between superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. However, most of the previous work was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. To overcome this limitation, we have used graphene grown by chemical vapour deposition (CVD) as the weak link of Josephson junctions. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in their electrical characteristics from 1.5 K down to a base temperature of 320 mK, and their gate-tuneable critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field. Furthermore, for our shortest junctions (50 nm in length), we find that the normal state resistance oscillates with the gate voltage, consistent with the junctions being in the ballistic regime, a feature not previously observed in CVD-graphene-based Josephson junctions.

Clogging and depinning of ballistic active matter systems in disordered media

Science.gov (United States)

Reichhardt, C.; Reichhardt, C. J. O.

2018-05-01

We numerically examine ballistic active disks driven through a random obstacle array. Formation of a pinned or clogged state occurs at much lower obstacle densities for the active disks than for passive disks. As a function of obstacle density, we identify several distinct phases including a depinned fluctuating cluster state, a pinned single-cluster or jammed state, a pinned multicluster state, a pinned gel state, and a pinned disordered state. At lower active disk densities, a drifting uniform liquid forms in the absence of obstacles, but when even a small number of obstacles are introduced, the disks organize into a pinned phase-separated cluster state in which clusters nucleate around the obstacles, similar to a wetting phenomenon. We examine how the depinning threshold changes as a function of disk or obstacle density and find a crossover from a collectively pinned cluster state to a disordered plastic depinning transition as a function of increasing obstacle density. We compare this to the behavior of nonballistic active particles and show that as we vary the activity from completely passive to completely ballistic, a clogged phase-separated state appears in both the active and passive limits, while for intermediate activity, a readily flowing liquid state appears and there is an optimal activity level that maximizes the flux through the sample.

Noninteracting beams of ballistic two-dimensional electrons

International Nuclear Information System (INIS)

Spector, J.; Stormer, H.L.; Baldwin, K.W.; Pfeiffer, L.N.; West, K.W.

1991-01-01

We demonstrate that two beams of two-dimensional ballistic electrons in a GaAs-AlGaAs heterostructure can penetrate each other with negligible mutual interaction analogous to the penetration of two optical beams. This allows electrical signal channels to intersect in the same plane with negligible crosstalk between the channels

HVI Ballistic Limit Charaterization of Fused Silica Thermal Pane

Science.gov (United States)

Bohl, William E.; Miller, Joshua E.; Christiansen, Eric L.; Deighton, Kevin.; Davis, Bruce

2015-01-01

The Orion spacecraft's windows are exposed to the micrometeroid and orbital debris (MMOD) space environments while in space as well as the Earth entry environment at the mission's conclusion. The need for a low-mass spacecraft window design drives the need to reduce conservatism when assessing the design for loss of crew due to MMOD impact and subsequent Earth entry. Therefore, work is underway at NASA and Lockheed Martin to improve characterization of the complete penetration ballistic limit of an outer fused silica thermal pane. Hypervelocity impact tests of the window configuration at up to 10 km/s and hydrocode modeling have been performed with a variety of projectile materials to enable refinement of the fused silica ballistic limit equation.

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

Science.gov (United States)

Lo, Kam W; Ferguson, Brian G

2012-11-01

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

Cost Effective Regional Ballistic Missile Defense

Science.gov (United States)

2016-02-16

deploying advanced air defense systems18, such as the Russian S-300 and S-500, and concealing them in hardened, camouflaged sites, such as extensive... Russian objections to the European Phased Adaptive Approach (EPAA) and fund homeland defense priorities.39 Furthermore, the PTSS system was also... Theatre Ballistic Missile Defence Capability Becomes Operational,” Jane’s Missiles & Rockets, 1 February 2011. 55 Joseph W. Kirschbaum, REGIONAL MISSILE

Toward Better Personal Ballistic Protection

Science.gov (United States)

2014-03-04

Toward Better Personal Ballistic Protection Manon Bolduc1, Jason Lo2, Ruby Zhang2, Dan Walsh2, Shuqiong Lin3, Benoit Simard3, Ken Bosnick4, Mike...presenc particulate gr atly increase ceramic mad er, knowing e ceramic ma the alumina y on the mat a layered with s on the coat stantial prope C) magnif...mic fiber ma site ceramics such, thod. this fore, on of t has 8. CONCLUSION In an attempt to improve the failure resistance of ceramic

Institute for Non-Lethal Defense Technologies Report: Ballistic Gelatin

National Research Council Canada - National Science Library

Nicholas, N. C; Welsch, J. R

2004-01-01

Ballistic gelatin is designed to simulate living soft tissue. It is the standard for evaluating the effectiveness of firearms against humans because of its convenience and acceptability over animal or cadaver testing...

Enhancement of wear and ballistic resistance of armour grade AA7075 aluminium alloy using friction stir processing

Directory of Open Access Journals (Sweden)

I. Sudhakar

2015-03-01

Full Text Available Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys, 7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant MoS2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.

A nanomagnetic study of phase transition in manganite thin films and ballistic magnetoresistance in magnetic nanocontacts

Science.gov (United States)

Chung, Seok-Hwan

This work focuses on two largely unexplored phenomena in micromagnetics: the temperature-driven paramagnetic insulator to ferromagnetic (FM) metallic phase transition in perovskite manganite and ballistic magnetoresistance in spin-polarized nanocontacts. To investigate the phase transition, an off-the-shelf commercial scanning force microscope was redesigned for operation at temperatures from 350 K to 100 K. This adaptation is elaborated in this thesis. Using this system, both ferromagnetic and charge-ordered domain structures of (La 1-xPrx)0.67Ca0.33MnO3 thin film were observed by magnetic force microscopy (MFM) and electric force microscopy (EFM) operated in the vicinity of the peak resistance temperature (Tp). Predominantly in-plane oriented FM domains of sub-micrometer size emerge below Tp and their local magnetic moment increased as the temperature is reduced. Charge-ordered insulating regions show a strong electrostatic interaction with an EFM tip at a few degrees above Tp and the interaction correlates well with the temperature dependence of resistivity of the film. Cross-correlation analysis between topography and magnetic structure on several substrates indicates FM domains form on the flat regions of the surface, while charge ordering occurs at surface protrusions. In the investigation of ballistic magnetoresistance, new results on half-metallic ferromagnets formed by atomic or nanometer contacts of CrO2-CrO 2 and CrO2-Ni are presented showing magnetoconductance as high as 400%. Analysis of the magnetoconductance versus conductance data for all materials known to exhibit so-called ballistic magnetoresistance strongly suggests that magnetoconductance of nanocontacts follows a universal mechanism. If the maximum magnetoconductance is normalized to unity and the conductance is scaled with the resistivity of the material, then all data points fall onto a universal curve independent of the contact material and the transport mechanism. The analysis has been

The Internal Ballistics of an Air Gun

Science.gov (United States)

Denny, Mark

2011-01-01

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

Ballistic Performance of Mallow and Jute Natural Fabrics Reinforced Epoxy Composites in Multilayered Armor

OpenAIRE

Nascimento, Lucio Fabio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Gomes, Alaelson Vieira; Marçal, Rubens Lincoln Santana Blazutti; Lima Júnior, Édio Pereira; Margem, Jean Igor

2017-01-01

Natural fiber reinforced polymer composites have recently been investigated as a component of multilayered armor system (MAS). These composites were found to present advantages when replacing conventional high strength synthetic aramid fabric laminate composite (KevlarTM, with same thickness, as MAS second layer. Continuous and loose natural fibers were up to now mostly used to reinforce these ballistic composites. Only two natural fabrics reinforced polymer composite were so far used with sa...

Split-Channel Ballistic Transport in an InSb Nanowire

Science.gov (United States)

Estrada Saldaña, Juan Carlos; Niquet, Yann-Michel; Cleuziou, Jean-Pierre; Lee, Eduardo J. H.; Car, Diana; Plissard, Sébastien R.; Bakkers, Erik P. A. M.; De Franceschi, Silvano

2018-04-01

We report an experimental study of one-dimensional (1D) electronic transport in an InSb semiconducting nanowire. Three bottom gates are used to locally deplete the nanowire creating a ballistic quantum point contact with only a few conducting channels. In a magnetic field, the Zeeman splitting of the corresponding 1D subbands is revealed by the emergence of conductance plateaus at multiples of $e^2$/h, yet we find a quantized conductance pattern largely dependent on the configuration of voltages applied to the bottom gates. In particular, we can make the first plateau disappear leaving a first conductance step of 2$e^2/h$, which is indicative of a remarkable two-fold subband degeneracy that can persist up to several Tesla. For certain gate voltage settings, we also observe the presence of discrete resonant states producing conductance features that can resemble those expected from the opening of a helical gap in the subband structure. We explain our experimental findings through the formation of two spatially separated 1D conduction channels.

Elements of sub-quantum thermodynamics: quantum motion as ballistic diffusion

International Nuclear Information System (INIS)

Groessing, G; Fussy, S; Pascasio, J Mesa; Schwabl, H

2011-01-01

By modelling quantum systems as emerging from a (classical) sub-quantum thermodynamics, the quantum mechanical 'decay of the wave packet' is shown to simply result from sub-quantum diffusion with a specific diffusion coefficient varying in time due to a particle's changing thermal environment. It is thereby proven that free quantum motion strictly equals ballistic diffusion. The exact quantum mechanical trajectory distributions and the velocity field of the Gaussian wave packet are thus derived solely from classical physics. Moreover, also quantum motion in a linear (e.g., gravitational) potential is shown to equal said ballistic diffusion. Quantitative statements on the trajectories' characteristic behaviours are obtained which provide a detailed 'micro-causal' explanation in full accordance with momentum conservation.

Viscoelastic shock wave in ballistic gelatin behind soft body armor.

Science.gov (United States)

Liu, Li; Fan, Yurun; Li, Wei

2014-06-01

Ballistic gelatins are widely used as a surrogate of biological tissue in blunt trauma tests. Non-penetration impact tests of handgun bullets on the 10wt% ballistic gelatin block behind soft armor were carried out in which a high-speed camera recorded the crater׳s movement and pressure sensors imbedded in the gelatin block recorded the pressure waves at different locations. The observed shock wave attenuation indicates the necessity of considering the gelatin׳s viscoelasticity. A three-element viscoelastic constitutive model was adopted, in which the relevant parameters were obtained via fitting the damping free oscillations at the beginning of the creep-mode of rheological measurement, and by examining the data of published split Hopkinson pressure bar (SHPB) experiments. The viscoelastic model is determined by a retardation time of 5.5×10(-5)s for high oscillation frequencies and a stress relaxation time of 2.0-4.5×10(-7)s for shock wave attenuation. Using the characteristic-line method and the spherical wave assumption, the propagation of impact pressure wave front and the subsequent unloading profile can be simulated using the experimental velocity boundary condition. The established viscoelastic model considerably improves the prediction of shock wave attenuation in the ballistic gelatin. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Advantages of Normalizing Electromyography to Ballistic Rather than Isometric or Isokinetic Tasks.

Science.gov (United States)

Suydam, Stephen M; Manal, Kurt; Buchanan, Thomas S

2017-07-01

Isometric tasks have been a standard for electromyography (EMG) normalization stemming from anatomic and physiologic stability observed during contraction. Ballistic dynamic tasks have the benefit of eliciting maximum EMG signals for normalization, despite having the potential for greater signal variability. It is the purpose of this study to compare maximum voluntary isometric contraction (MVIC) to nonisometric tasks with increasing degrees of extrinsic variability, ie, joint range of motion, velocity, rate of contraction, etc., to determine if the ballistic tasks, which elicit larger peak EMG signals, are more reliable than the constrained MVIC. Fifteen subjects performed MVIC, isokinetic, maximum countermovement jump, and sprint tasks while EMG was collected from 9 muscles in the quadriceps, hamstrings, and lower leg. The results revealed the unconstrained ballistic tasks were more reliable compared to the constrained MVIC and isokinetic tasks for all triceps surae muscles. The EMG from sprinting was more reliable than the constrained cases for both the hamstrings and vasti. The most reliable EMG signals occurred when the body was permitted its natural, unconstrained motion. These results suggest that EMG is best normalized using ballistic tasks to provide the greatest within-subject reliability, which beneficially yield maximum EMG values.

Fabry-Perot magnonic ballistic coherent transport across ultrathin ferromagnetic lamellar bcc Ni nanostructures between Fe leads

Science.gov (United States)

Khater, A.; Saim, L.; Tigrine, R.; Ghader, D.

2018-06-01

We propose thermodynamically stable systems of ultrathin lamellar bcc Ni nanostructures between bcc Fe leads, sbnd Fe[Ni(n)]Fesbnd , based on the available literature for bcc Ni overlayers on Fe(001) surfaces, and establish the necessary criteria for their structural and ferromagnetic order, for thicknesses n ≤ 6 bcc Ni monatomic layers. The system is globally ferromagnetic. A theoretical model is presented to investigate and understand the ballistic coherent scattering of Fe spin-waves, incident from the leads, at the ferromagnetic bcc Ni nanostructure. The Nisbnd Ni and Nisbnd Fe exchange are computed using the Ising effective field theory (EFT), and the magnetic ground state of the system is constructed in the Heisenberg representation. We compute the spin-wave eigenmodes localized on the bcc Ni nanostructure, using the phase field matching theory (PFMT), illustrating the effects of symmetry breaking on the confinement of localized spin excitations. The reflection and transmission scattering properties of spin-waves incident from the Fe leads, across the embedded Ni nanostructures are investigated within the framework of the same PFMT methodology. A highly refined Fabry-Perot magnonic ballistic coherent transmission spectra is observed for these sbnd Fe[Ni(n)]Fesbnd systems.

Measurements of the ballistic-phonon component resulting from nuclear and electron recoils in crystalline silicon

International Nuclear Information System (INIS)

Lee, A.T.; Cabrera, B.; Dougherty, B.L.; Penn, M.J.; Pronko, J.G.; Tamura, S.

1996-01-01

We present measurements of the ballistic-phonon component resulting from nuclear and electron recoils in silicon at ∼380 mK. The detectors used for these experiments consist of a 300-μm-thick monocrystal of silicon instrumented with superconducting titanium transition-edge sensors. These sensors detect the initial wavefront of athermal phonons and give a pulse height that is sensitive to changes in surface-energy density resulting from the focusing of ballistic phonons. Nuclear recoils were generated by neutron bombardment of the detector. A Van de Graaff proton accelerator and a thick 7 Li target were used. Pulse-height spectra were compared for neutron, x-ray, and γ-ray events. A previous analysis of this data set found evidence for an increase in the ballistic-phonon component for nuclear recoils compared to electron recoils at a 95% confidence level. An improved understanding of the detector response has led to a change in the result. In the present analysis, the data are consistent with no increase at the 68% confidence level. This change stems from an increase in the uncertainty of the result rather than a significant change in the central value. The increase in ballistic phonon energy for nuclear recoils compared to electron recoils as a fraction of the total phonon energy (for equal total phonon energy events) was found to be 0.024 +0.041 -0.055 (68% confidence level). This result sets a limit of 11.6% (95% confidence level) on the ballistic phonon enhancement for nuclear recoils predicted by open-quote open-quote hot spot close-quote close-quote and electron-hole droplet models, which is the most stringent to date. To measure the ballistic-phonon component resulting from electron recoils, the pulse height as a function of event depth was compared to that of phonon simulations. (Abstract Truncated)

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

Science.gov (United States)

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found in armor structures made of high...mechanisms, friction stir welding M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen, B. A. Cheeseman Clemson University Office of Sponsored Programs 300

Validation of the NATO Armaments Ballistic Kernel for use in small-arms fire control systems

Directory of Open Access Journals (Sweden)

D. Corriveau

2017-06-01

Full Text Available In support for the development of a new small-arm ballistic computer based on the NATO Armaments Ballistic Kernel (NABK for the Canadian snipers, DRDC Valcartier Research Centre was asked to carry out high-fidelity 6 degree-of-freedom (6-DOF trajectory simulations for a set of relevant vignettes for the snipers, and to compare the direct fire 6-DOF simulation results with those obtained with the 4-DOF NATO Armaments Ballistic Kernel (NABK adapted to simulate small-arm ammunition trajectories. To conduct this study, DRDC Valcartier Research Centre used BALCO v1.0b. This paper presents (1 the process and the methodology employed to carry out the sniper direct fire solution study, (2 the modeling and the simulation of the sniper projectile, the approach used in calculating the firing solutions, and the results of direct fire simulations for the sniper vignettes, and (3 an analysis of firing solutions obtained with the BALCO engine versus those of NABK. The work presented in this paper serves to validate the use of NABK for the new sniper ballistic computer.

Multi-valued logic gates based on ballistic transport in quantum point contacts.

Science.gov (United States)

Seo, M; Hong, C; Lee, S-Y; Choi, H K; Kim, N; Chung, Y; Umansky, V; Mahalu, D

2014-01-22

Multi-valued logic gates, which can handle quaternary numbers as inputs, are developed by exploiting the ballistic transport properties of quantum point contacts in series. The principle of a logic gate that finds the minimum of two quaternary number inputs is demonstrated. The device is scalable to allow multiple inputs, which makes it possible to find the minimum of multiple inputs in a single gate operation. Also, the principle of a half-adder for quaternary number inputs is demonstrated. First, an adder that adds up two quaternary numbers and outputs the sum of inputs is demonstrated. Second, a device to express the sum of the adder into two quaternary digits [Carry (first digit) and Sum (second digit)] is demonstrated. All the logic gates presented in this paper can in principle be extended to allow decimal number inputs with high quality QPCs.

Multi-Valued Logic Gates based on Ballistic Transport in Quantum Point Contacts

Science.gov (United States)

Seo, M.; Hong, C.; Lee, S.-Y.; Choi, H. K.; Kim, N.; Chung, Y.; Umansky, V.; Mahalu, D.

2014-01-01

Multi-valued logic gates, which can handle quaternary numbers as inputs, are developed by exploiting the ballistic transport properties of quantum point contacts in series. The principle of a logic gate that finds the minimum of two quaternary number inputs is demonstrated. The device is scalable to allow multiple inputs, which makes it possible to find the minimum of multiple inputs in a single gate operation. Also, the principle of a half-adder for quaternary number inputs is demonstrated. First, an adder that adds up two quaternary numbers and outputs the sum of inputs is demonstrated. Second, a device to express the sum of the adder into two quaternary digits [Carry (first digit) and Sum (second digit)] is demonstrated. All the logic gates presented in this paper can in principle be extended to allow decimal number inputs with high quality QPCs.

A brief review of strength and ballistic assessment methodologies in sport.

Science.gov (United States)

McMaster, Daniel Travis; Gill, Nicholas; Cronin, John; McGuigan, Michael

2014-05-01

An athletic profile should encompass the physiological, biomechanical, anthropometric and performance measures pertinent to the athlete's sport and discipline. The measurement systems and procedures used to create these profiles are constantly evolving and becoming more precise and practical. This is a review of strength and ballistic assessment methodologies used in sport, a critique of current maximum strength [one-repetition maximum (1RM) and isometric strength] and ballistic performance (bench throw and jump capabilities) assessments for the purpose of informing practitioners and evolving current assessment methodologies. The reliability of the various maximum strength and ballistic assessment methodologies were reported in the form of intra-class correlation coefficients (ICC) and coefficient of variation (%CV). Mean percent differences (Mdiff = [/Xmethod1 - Xmethod2/ / (Xmethod1 + Xmethod2)] x 100) and effect size (ES = [Xmethod2 - Xmethod1] ÷ SDmethod1) calculations were used to assess the magnitude and spread of methodological differences for a given performance measure of the included studies. Studies were grouped and compared according to their respective performance measure and movement pattern. The various measurement systems (e.g., force plates, position transducers, accelerometers, jump mats, optical motion sensors and jump-and-reach apparatuses) and assessment procedures (i.e., warm-up strategies, loading schemes and rest periods) currently used to assess maximum isometric squat and mid-thigh pull strength (ICC > 0.95; CV 0.91; CV ballistic (vertical jump and bench throw) capabilities (ICC > 0.82; CV ballistic performance in recreational and elite athletes, alike. However, the reader needs to be cognisant of the inherent differences between measurement systems, as selection will inevitably affect the outcome measure. The strength and conditioning practitioner should also carefully consider the benefits and limitations of the different measurement

Gate controlled high efficiency ballistic energy conversion system

NARCIS (Netherlands)

Xie, Yanbo; Bos, Diederik; de Boer, Hans L.; van den Berg, Albert; Eijkel, Jan C.T.; Zengerle, R.

2013-01-01

Last year we demonstrated the microjet ballistic energy conversion system[1]. Here we show that the efficiency of such a system can be further improved by gate control. With gate control the electrical current generation is enhanced a hundred times with respect to the current generated from the zeta

Electron optics with ballistic graphene junctions

Science.gov (United States)

Chen, Shaowen

Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

Image-guided percutaneous removal of ballistic foreign bodies secondary to air gun injuries.

Science.gov (United States)

Rothermund, Jacob L; Rabe, Andrew J; Zumberge, Nicholas A; Murakami, James W; Warren, Patrick S; Hogan, Mark J

2018-01-01

Ballistic injuries with retained foreign bodies from air guns is a relatively common problem, particularly in children and adolescents. If not removed in a timely fashion, the foreign bodies can result in complications, including pain and infection. Diagnostic methods to identify the presence of the foreign body run the entire gamut of radiology, particularly radiography, ultrasound (US) and computed tomography (CT). Removal of the foreign bodies can be performed by primary care, emergency, surgical, and radiologic clinicians, with or without imaging guidance. To evaluate the modalities of radiologic detection and the experience of image-guided ballistic foreign body removal related to air gun injuries within the interventional radiology department of a large pediatric hospital. A database of more than 1,000 foreign bodies that were removed with imaging guidance by the interventional radiologists at our institution was searched for ballistic foreign bodies from air guns. The location, dimensions, diagnostic modality, duration, complications and imaging modality used for removal were recorded. In addition, the use of sedation and anesthesia required for the procedures was also recorded. Sixty-one patients with ballistic foreign bodies were identified. All foreign bodies were metallic BBs or pellets. The age of the patients ranged from 5 to 20 years. The initial diagnostic modality to detect the foreign bodies was primarily radiography. The primary modality to assist in removal was US, closely followed by fluoroscopy. For the procedure, 32.7% of the patients required some level of sedation. Only two patients had an active infection at the time of the removal. The foreign bodies were primarily in the soft tissues; however, successful removal was also performed from intraosseous, intraglandular and intratendinous locations. All cases resulted in successful removal without complications. Image-guided removal of ballistic foreign bodies secondary to air guns is a very

Surgeon preferences regarding antibiotic prophylaxis for ballistic fractures.

Science.gov (United States)

Marecek, Geoffrey S; Earhart, Jeffrey S; Gardner, Michael J; Davis, Jason; Merk, Bradley R

2016-06-01

Scant evidence exists to support antibiotic use for low velocity ballistic fractures (LVBF). We therefore sought to define current practice patterns. We hypothesized that most surgeons prescribe antibiotics for LVBF, prescribing is not driven by institutional protocols, and that decisions are based on protocols utilized for blunt trauma. A web-based questionnaire was emailed to the membership of the Orthopaedic Trauma Association (OTA). The questionnaire included demographic information and questions about LVBF treatment practices. Two hundred and twenty surgeons responded. One hundred and fifty-four (70 %) respondents worked at a Level-1 trauma center, 176 (80 %) had received fellowship education in orthopaedic trauma and 104 (47 %) treated at least 10 ballistic fractures annually. Responses were analyzed with SAS 9.3 for Windows (SAS Institute Inc, Cary, NC). One hundred eighty-six respondents (86 %) routinely provide antibiotics for LVBF. Those who did not were more apt to do so for intra-articular fractures (8/16, 50 %) and pelvic fractures with visceral injury (10/16, 63 %). Most surgeons (167, 76 %) do not believe the Gustilo-Anderson classification applies to ballistic fractures, and (20/29, 70 %) do not base their antibiotic choice on the classification system. Few institutions (58, 26 %) have protocols guiding antibiotic use for LVBF. Routine antibiotic use for LVBF is common; however, practice is not dictated by institutional protocol. Although antibiotic use generally follows current blunt trauma guidelines, surgeons do not base their treatment decisions the Gustilo-Anderson classification. Given the high rate of antibiotic use for LVBF, further study should focus on providing evidence-based treatment guidelines.

Designing an Innovative Composite Armor System for Affordable Ballistic Protection

National Research Council Canada - National Science Library

Ma, Zheng-Dong; Wang, Hui; Cui, Yushun; Rose, Douglas; Socks, Adria; Ostberg, Donald

2006-01-01

.... This paper focuses on the frontal armor plate and back plate design problems with demonstration examples, including both results of the virtual prototyping and ballistic testing for proof-of-concept...

Penetrating chest trauma caused by a blank cartridge actuated rubber ball projectile: case presentation and ballistic investigation of an uncommon weapon type.

Science.gov (United States)

Frank, Matthias; Peters, Dieter; Klemm, Wolfram; Grossjohann, Rico; Ekkernkamp, Axel; Bockholdt, Britta; Seifert, Julia

2017-09-01

Recently, an increasing number of an uncommon weapon type based on a caliber 6-mm Flobert blank cartridge actuated revolver which discharges 10-mm-diameter rubber ball projectiles has been confiscated by police authorities following criminal offenses. A recent trauma case presenting with a penetrating chest injury occasioned an investigation into the basic ballistic parameters of this type of weapon. Kinetic energy E of the test projectiles was calculated between 5.8 and 12.5 J. Energy density ED of the test projectiles was close to or higher than the threshold energy density of human skin. It can be concluded that penetrating skin injuries due to free-flying rubber ball projectiles discharged at close range cannot be ruled out. However, in case of a contact shot, the main injury potential of this weapon type must be attributed to the high energy density of the muzzle gas jet which may, similar to well-known gas or alarm weapons, cause life-threatening or even lethal injuries.

Determination of the propellant combustion law under ballistic experiment conditions

Science.gov (United States)

Ishchenko, A. N.; Diachkovskii, A. S.; Zykova, A. I.; Kasimov, VZ; Samorokova, N. M.

2017-11-01

The main characteristics of ballistic experiment are the maximum pressure in the combustion chamber P max and the projectile velocity at the time of barrel leaving U M. During the work the burning law of the new high-energy fuel was determined in a ballistic experiment. This burning law was used for a parametric study of depending P max and U M from a powder charge mass and a traveling charge at initial temperature of + 20 °C was carried out. The optimal conditions for loading were obtained for improving the muzzle velocity by 14.9 %. Under optimal loading, there is defined the conditions, which is possible to get the greatest value muzzle velocity projectile at pressures up to 600 MPa.

Determine ISS Soyuz Orbital Module Ballistic Limits for Steel Projectiles Hypervelocity Impact Testing

Science.gov (United States)

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.

Ballistic Spin Field Effect Transistor Based on Silicon Nanowires

Science.gov (United States)

Osintsev, Dmitri; Sverdlov, Viktor; Stanojevic, Zlatan; Selberherr, Siegfried

2011-03-01

We investigate the properties of ballistic spin field-effect transistors build on silicon nanowires. An accurate description of the conduction band based on the k . p} model is necessary in thin and narrow silicon nanostructures. The subband effective mass and subband splitting dependence on the nanowire dimensions is analyzed and used in the transport calculations. The spin transistor is formed by sandwiching the nanowire between two ferromagnetic metallic contacts. Delta-function barriers at the interfaces between the contacts and the silicon channel are introduced. The major contribution to the electric field-dependent spin-orbit interaction in confined silicon systems is due to the interface-induced inversion asymmetry which is of the Dresselhaus type. We study the current and conductance through the system for the contacts being in parallel and anti-parallel configurations. Differences between the [100] and [110] orientated structures are investigated in details. This work is supported by the European Research Council through the grant #247056 MOSILSPIN.

Influence of Material Properties on the Ballistic Performance of Ceramics for Personal Body Armour

OpenAIRE

Kaufmann, Christian; Cronin, Duane; Worswick, Michael; Pageau, Gilles; Beth, Andre

2003-01-01

In support of improved personal armour development, depth of penetration tests have been conducted on four different ceramic materials including alumina, modified alumina, silicon carbide and boron carbide. These experiments consisted of impacting ceramic tiles bonded to aluminum cylinders with 0.50 caliber armour piercing projectiles. The results are presented in terms of ballistic efficiency, and the validity of using ballistic efficiency as a measure of ceramic performance was examined. In...

The method of neutron imaging as a tool for the study of the dynamics of water movement in wet aramid-based ballistic body armour panels

Science.gov (United States)

Reifler, Felix A.; Lehmann, Eberhard H.; Frei, Gabriel; May, Hans; Rossi, René

2006-07-01

A new non-destructive method based on neutron imaging (neutron radiography) to determine the exact water content in aramid-based soft body armour panels is presented. While investigating the ballistic resistance of aramid-based body armour panels under a wet condition, it is important to precisely determine their water content and its chronological development. Using the presented method, the influence of water amount and location on impact testing as well as its time dependence was shown. In the ballistic panels used, spreading of water strongly depended on the kind of quilting. Very fast water migration could be observed when the panels were held vertically. Some first results regarding the water distribution in wet panels immediately after the impact are presented. On the basis of the presented results, requirements for a standard for testing the performance of ballistic panels in the wet state are deduced.

Deformations on Hole and Projectile Surfaces Caused By High Velocity Friction During Ballistic Impact

Science.gov (United States)

Karamış, M. B.

2018-01-01

In this study, the deformations caused by the ballistic impact on the MM composites and on projectile surfaces are examined. The hole section and grain deformation of unreinforced targets are also examined after impact. The relatively high complexity of impact problems is caused by the large number of intervening parameters like relative velocity of projectile and target, shape of colliding objects, relative stiffness and masses, time-dependent surface of contact, geometry and boundary conditions and material characteristics. The material used in this investigation are 2024 and 7075 aluminum alloys as matrix reinforced with SiC and Al2O3 particles. The matrix materials are extensively used in defense applications due to its favorable ballistic properties, moderate strength, high corrosion resistance and super plastic potential. Two different composites were produced; one by casting and the other by lamination. The ballistic tests of the composite targets were carried out according to NIJ Standard-0101.04, Temperature 21 °C, RH=65% with 7.62 mm projectiles. The bullet weight was 9.6 g and their muzzle velocities were in the range of 770-800 m/s. The projectiles consisted of a steel core, copper jacket and lead material. The composite targets were positioned 15 m from the rifle. The interaction between projectiles and the target hole created after impact were examined by light microscopy and photography. Different damage and failure mechanisms such as petalling, cracking, spalling, dishing, etc., were observed on the target body. On the other hand, dramatic wear and damages on the projectile surface were also observed. The targets were supported with Al-5083 backing blocks having 40 mm thickness.

Ballistic energy transport via perfluoroalkane linkers

Energy Technology Data Exchange (ETDEWEB)

Rubtsova, Natalia I. [Department of Chemistry, Tulane University, New Orleans, LA 70118 (United States); Rubtsov, Igor V., E-mail: irubtsov@tulane.edu [Department of Chemistry, Tulane University, New Orleans, LA 70118 (United States)

2013-08-30

Highlights: ► Energy transport in perfluoroalkanes oligomers of various chain lengths was studied. ► Cross-peaks among C=O stretch and CH bending modes were recorded using RA 2DIR. ► Efficient constant-speed energy transport with the speed of 1150 m/s is found. ► Ballistic energy transport mechanism is suggested. - Abstract: Intramolecular energy transport in a series of perfluoroalkane oligomers with various chain lengths of 3, 5, 7, 9, and 11 carbon atoms terminated by a carboxylic acid moiety on one end and –CF{sub 2}H group on another end is studied by relaxation-assisted two-dimensional infrared spectroscopy. Perfluoroalkane oligomers adopt an extended structure with antiperiplanar orientation of the neighboring carbon atoms. The energy transport initiated by exciting the C=O stretching mode of the acid was recorded by measuring a cross-peak amplitude between the C=O stretch and the C–H bending mode as a function of the waiting time between the excitation and probing. A linear dependence of energy transport time vs. chain length is found, which suggests a ballistic energy transport mechanism. The energy transport speed, measured from the chain-length dependence of the half-rise time, T{sub ½}, was found to be ca. 1150 m/s, which is close to the longitudinal speed of sound in Teflon polymers.

Instantaneous ballistic velocity of suspended Brownian nanocrystals measured by upconversion nanothermometry

Science.gov (United States)

Brites, Carlos D. S.; Xie, Xiaoji; Debasu, Mengistie L.; Qin, Xian; Chen, Runfeng; Huang, Wei; Rocha, João; Liu, Xiaogang; Carlos, Luís D.

2016-10-01

Brownian motion is one of the most fascinating phenomena in nature. Its conceptual implications have a profound impact in almost every field of science and even economics, from dissipative processes in thermodynamic systems, gene therapy in biomedical research, artificial motors and galaxy formation to the behaviour of stock prices. However, despite extensive experimental investigations, the basic microscopic knowledge of prototypical systems such as colloidal particles in a fluid is still far from being complete. This is particularly the case for the measurement of the particles' instantaneous velocities, elusive due to the rapid random movements on extremely short timescales. Here, we report the measurement of the instantaneous ballistic velocity of Brownian nanocrystals suspended in both aqueous and organic solvents. To achieve this, we develop a technique based on upconversion nanothermometry. We find that the population of excited electronic states in NaYF4:Yb/Er nanocrystals at thermal equilibrium can be used for temperature mapping of the nanofluid with great thermal sensitivity (1.15% K-1 at 296 K) and a high spatial resolution (<1 μm). A distinct correlation between the heat flux in the nanofluid and the temporal evolution of Er3+ emission allows us to measure the instantaneous velocity of nanocrystals with different sizes and shapes.

Ballistic Characterization Of A Typical Military Steel Helmet

Directory of Open Access Journals (Sweden)

Mohamed Ali Maher

2017-08-01

Full Text Available In this study the ballistic limit of a steel helmet against a FMJ 919 mm caliber bullet is estimated. The helmet model is the typical polish helmet wz.31.The helmet material showed high strength low alloy steel material of 0.28 carbon content and 9.125 kgm2 areal density. The tensile test according to ASTM E8 showed a tensile strength of 1236.4 MPa .The average hardness value was about HV550. First shooting experiment has been executed using a 9 mm pistol based on 350 ms muzzle velocity at 5m against the simply supported helmet complete penetrations rose in this test were in the form of cracks on the helmet surface and partial penetrations were in the form of craters on the surface whose largest diameter and depth were 43 mm and 20.2 mm consequently .The second experiment was on a rifled gun arrangement 13 bullets of 919 mm caliber were shot on the examined simply supported steel helmet at a zero obliquity angle at different velocities to determine the ballistic limit velocity V50 according to MIL-STD-662F. Three major outcomes were revealed 1 the value V50 which found to be about 390 ms is higher than the one found in literature 360 ms German steel helmet model 1A1. 2 The smallest the standard deviation of the mixed results zone data the most accurate the ballistic limit is. 3Similar to the performance of blunt-ended projectiles impacting overmatching targets tD near 11 or larger It was found that the dominating failure mode of the steel helmet stuck by a hemispherical-nose projectile was plugging mode despite of having tD ratio of about 19 undermatching.

Ballistic transport in graphene grown by chemical vapor deposition

NARCIS (Netherlands)

Calado, V.E.; Zhu, S.E.; Goswami, S.; Xu, Q.; Watanabe, K.; Taniguchi, T.; Janssen, G.C.A.M.; Vandersypen, L.M.K.

2014-01-01

In this letter, we report the observation of ballistic transport on micron length scales in graphene synthesised by chemical vapour deposition (CVD). Transport measurements were done on Hall bar geometries in a liquid He cryostat. Using non-local measurements, we show that electrons can be

Graphene ballistic nano-rectifier with very high responsivity

Science.gov (United States)

Auton, Gregory; Zhang, Jiawei; Kumar, Roshan Krishna; Wang, Hanbin; Zhang, Xijian; Wang, Qingpu; Hill, Ernie; Song, Aimin

2016-01-01

Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ∼200,000 cm2 V−1 s−1 is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW−1 with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz−1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization. PMID:27241162

The Rise and Fall of Safeguard:Anti‐Ballistic Missile Technology and the Nixon Administration

OpenAIRE

Spinardi, Graham

2010-01-01

The Safeguard anti-ballistic missile system was the first (and up until 2002 the only) system deployed to defend the USA from nuclear-armed ballistic missile attack. It was finally declared operational in September 1975 after many years of development and fierce controversy over both its feasibility and its desirability. However, almost immediately Congress voted to close the system down and it was dismantled within a few months. This paper draws on documents available in the Nixon archives t...

Microbial arms race: Ballistic "nematocysts" in dinoflagellates represent a new extreme in organelle complexity.

Science.gov (United States)

Gavelis, Gregory S; Wakeman, Kevin C; Tillmann, Urban; Ripken, Christina; Mitarai, Satoshi; Herranz, Maria; Özbek, Suat; Holstein, Thomas; Keeling, Patrick J; Leander, Brian S

2017-03-01

We examine the origin of harpoon-like secretory organelles (nematocysts) in dinoflagellate protists. These ballistic organelles have been hypothesized to be homologous to similarly complex structures in animals (cnidarians); but we show, using structural, functional, and phylogenomic data, that nematocysts evolved independently in both lineages. We also recorded the first high-resolution videos of nematocyst discharge in dinoflagellates. Unexpectedly, our data suggest that different types of dinoflagellate nematocysts use two fundamentally different types of ballistic mechanisms: one type relies on a single pressurized capsule for propulsion, whereas the other type launches 11 to 15 projectiles from an arrangement similar to a Gatling gun. Despite their radical structural differences, these nematocysts share a single origin within dinoflagellates and both potentially use a contraction-based mechanism to generate ballistic force. The diversity of traits in dinoflagellate nematocysts demonstrates a stepwise route by which simple secretory structures diversified to yield elaborate subcellular weaponry.

Targeting Ballistic Lunar Capture Trajectories Using Periodic Orbits in the Sun-Earth CRTBP

Science.gov (United States)

Cooley, D.S.; Griesemer, Paul Ricord; Ocampo, Cesar

2009-01-01

A particular periodic orbit in the Earth-Sun circular restricted three body problem is shown to have the characteristics needed for a ballistic lunar capture transfer. An injection from a circular parking orbit into the periodic orbit serves as an initial guess for a targeting algorithm. By targeting appropriate parameters incrementally in increasingly complicated force models and using precise derivatives calculated from the state transition matrix, a reliable algorithm is produced. Ballistic lunar capture trajectories in restricted four body systems are shown to be able to be produced in a systematic way.

Orbital magnetism in ensembles of ballistic billiards

International Nuclear Information System (INIS)

Ullmo, D.; Richter, K.; Jalabert, R.A.

1993-01-01

The magnetic response of ensembles of small two-dimensional structures at finite temperatures is calculated. Using semiclassical methods and numerical calculation it is demonstrated that only short classical trajectories are relevant. The magnetic susceptibility is enhanced in regular systems, where these trajectories appear in families. For ensembles of squares large paramagnetic susceptibility is obtained, in good agreement with recent measurements in the ballistic regime. (authors). 20 refs., 2 figs

Strategic nuclear policy and ballistic missile defense

International Nuclear Information System (INIS)

1981-01-01

The article explains the problems of the antirockets (ABM) as they were part of the presentation Salt I 1972. It is a translation from the English of a publication of the Foreign Affairs Research Institute in London. A topical analysis of the strategic nuclear policy of the two superpowers and their attitudes in the question of ballistic missile defense are given by means of two monographies. (orig./HSCH) [de

Balancing ballistic protection against physiological strain: evidence from laboratory and field trials.

Science.gov (United States)

Taylor, Nigel A S; Burdon, Catriona A; van den Heuvel, Anne M J; Fogarty, Alison L; Notley, Sean R; Hunt, Andrew P; Billing, Daniel C; Drain, Jace R; Silk, Aaron J; Patterson, Mark J; Peoples, Gregory E

2016-02-01

This project was based on the premise that decisions concerning the ballistic protection provided to defence personnel should derive from an evaluation of the balance between protection level and its impact on physiological function, mobility, and operational capability. Civilians and soldiers participated in laboratory- and field-based studies in which ensembles providing five levels of ballistic protection were evaluated, each with progressive increases in protection, mass (3.4-11.0 kg), and surface-area coverage (0.25-0.52 m(2)). Physiological trials were conducted on volunteers (N = 8) in a laboratory, under hot-dry conditions simulating an urban patrol: walking at 4 km·h(-1) (90 min) and 6 km·h(-1) (30 min or to fatigue). Field-based trials were used to evaluate tactical battlefield movements (mobility) of soldiers (N = 31) under tropical conditions, and across functional tests of power, speed, agility, endurance, and balance. Finally, trials were conducted at a jungle training centre, with soldiers (N = 32) patrolling under tropical conditions (averaging 5 h). In the laboratory, work tolerance was reduced as protection increased, with deep-body temperature climbing relentlessly. However, the protective ensembles could be grouped into two equally stressful categories, each providing a different level of ballistic protection. This outcome was supported during the mobility trials, with the greatest performance decrement evident during fire and movement simulations, as the ensemble mass was increased (-2.12%·kg(-1)). The jungle patrol trials similarly supported this outcome. Therefore, although ballistic protection does increase physiological strain, this research has provided a basis on which to determine how that strain can be balanced against the mission-specific level of required personal protection.

Kinetic treatment of magnetosonic wave reflection by minority gyroresonant ballistic waves in tokamak geometry

International Nuclear Information System (INIS)

Kaufman, A.N.; Brizard, A.J.; Cook, D.R.

1993-01-01

The analysis of the minority-ion gyroresonant heating process by a magnetosonic wave in a general magnetic field geometry with one ignorable spatial coordinate can be divided into several steps, each defined in terms of a precise mathematical problem to be solved. In this work, the authors focus their attention on the magnetosonic wave reflection problem in axisymmetric tokamak geometry; the conversion and absorption of the minority-ion gyroresonant ballistic waves are treated elsewhere. In contrast to their previous work, they employ a kinetic model based on the perturbation generating function S for the gyroresonant minority-ions. The bulk plasma response is represented by the perturbation magnetic vector potential A, corresponding to a shielded magnetosonic wave. The set of coupled equations for S and A can be derived from an action principle, which can also be used to derive explicit wave-action conservation laws in ray phase space. The reflection problem is solved in ray phase space by considering three separate steps. In the first step, the incident magnetosonic ray propagates towards the first linear mode conversion region, where action is transferred to the minority-ion gyroresonant ballistic waves. In the second step, the continuum of excited gyroresonant ballistic rays propagate towards the second linear mode conversion region. In the third step, the reflected magnetosonic wave field is excited by linear mode conversion from the minority gyroresonant ballistic rays

Project, Aerodynamic, Thermal and Ballistic Analysis of a Lifting-Body Reentry Vehicle

Directory of Open Access Journals (Sweden)

A. N. Eliseev

2015-01-01

Full Text Available The objective of this article is to assess the prospects for an increasingly maneuverable reentry vehicle (RV of class "lifting body". In this regard, a project aerodynamic thermal and ballistic analysis has been conducted and the results have been compared with some well-known projects of the RV of the same class, made both in our country and abroad.The project analysis begins with finding a position of the "lifting body" vehicle in the classification system. Said classification distribution allows correct formulation of requirements for the conceptual structure of an aerospace vehicle at the initial stage of design in terms of system positions, since just the initial phase of the design often determines the success of the whole program.Then the paper compares design characteristics of the RV of class "lifting body" with vehicles such as X-15 rocket plane, the orbiter "Space Shuttle», M2-F2, HL-10, SV-5, and NASP "Hermes". It also gives a comparative estimate of the "lifting body" RV mass in a wide range of dimensions. The paper shows the sustainability of various landing complexes with reference to the Russian experience in developing the RV " Soyuz", and the conditions for using the vehicles of class "lifting body" in space programs.The aerodynamic analysis uses method for the approximate Newtonian theory to calculate aerodynamic characteristics of the perspective RV of class "lifting body" in the hypersonic descent phase. To obtain the desired aerodynamic performance and reduce balancing weight is contemplated a possibility to provide balance by introducing additional boards. The ballistic analysis considers four modes of descent:1. zero roll descent;2. maximum cross-range descent without restriction;3. maximum cross-range descent with restriction of maximum overload and maximum temperature;4. ballistic descent.To calculate the RV ballistic characteristics a system of equations of the vehicle motion in the atmosphere is used. The vehicle

MD Test of a Ballistic Optics

CERN Document Server

Garcia-Tabares Valdivieso, Ana; Salvachua Ferrando, Belen Maria; Skowronski, Piotr Krzysztof; Solfaroli Camillocci, Matteo; Tomas Garcia, Rogelio; Wenninger, Jorg; Coello De Portugal - Martinez Vazquez, Jaime Maria; CERN. Geneva. ATS Department

2016-01-01

The ballistic optics is designed to improve the understanding of optical errors and BPM systematic effects in the critical triplet region. The particularity of that optics is that the triplet is switched off, effectively transforming the triplets on both sides of IR1 and IR5 into drift spaces. Advantage can be taken from that fact to localize better errors in the Q4-Q5-triplet region. During this MD this new optics was tested for the first time at injection with beam 2.

The influence of ALN-Al gradient material gradient index on ballistic performance

International Nuclear Information System (INIS)

Wang Youcong; Liu Qiwen; Li Yao; Shen Qiang

2013-01-01

Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.

Ballistic Missile Defense: National Security and the High Frontier of Space.

Science.gov (United States)

Adragna, Steven P.

1985-01-01

Ballistic missile defense is discussed, and the rationale behind the proposal to place defensive weapons in space is examined. Strategic defense is a national security, political, and moral imperative. (RM)

Imaging ballistic carrier trajectories in graphene using scanning gate microscopy

Energy Technology Data Exchange (ETDEWEB)

Morikawa, Sei; Masubuchi, Satoru [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Dou, Ziwei; Wang, Shu-Wei; Smith, Charles G.; Connolly, Malcolm R., E-mail: mrc61@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Machida, Tomoki, E-mail: tmachida@iis.u-tokyo.ac.jp [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

2015-12-14

We use scanning gate microscopy to map out the trajectories of ballistic carriers in high-mobility graphene encapsulated by hexagonal boron nitride and subject to a weak magnetic field. We employ a magnetic focusing geometry to image carriers that emerge ballistically from an injector, follow a cyclotron path due to the Lorentz force from an applied magnetic field, and land on an adjacent collector probe. The local electric field generated by the scanning tip in the vicinity of the carriers deflects their trajectories, modifying the proportion of carriers focused into the collector. By measuring the voltage at the collector while scanning the tip, we are able to obtain images with arcs that are consistent with the expected cyclotron motion. We also demonstrate that the tip can be used to redirect misaligned carriers back to the collector.

Voluntary Control of Residual Antagonistic Muscles in Transtibial Amputees: Feedforward Ballistic Contractions and Implications for Direct Neural Control of Powered Lower Limb Prostheses.

Science.gov (United States)

Huang, Stephanie; Huang, He

2018-04-01

Discrete, rapid (i.e., ballistic like) muscle activation patterns have been observed in ankle muscles (i.e., plantar flexors and dorsiflexors) of able-bodied individuals during voluntary posture control. This observation motivated us to investigate whether transtibial amputees are capable of generating such a ballistic-like activation pattern accurately using their residual ankle muscles in order to assess whether the volitional postural control of a powered ankle prosthesis using proportional myoelectric control via residual muscles could be feasible. In this paper, we asked ten transtibial amputees to generate ballistic-like activation patterns using their residual lateral gastrocnemius and residual tibialis anterior to control a computer cursor via proportional myoelectric control to hit targets positioned at 20% and 40% of maximum voluntary contraction of the corresponding residual muscle. During practice conditions, we asked amputees to hit a single target repeatedly. During testing conditions, we asked amputees to hit a random sequence of targets. We compared movement time to target and end-point accuracy. We also examined motor recruitment synchronization via time-frequency representations of residual muscle activation. The result showed that median end-point error ranged from -0.6% to 1% maximum voluntary contraction across subjects during practice, which was significantly lower compared to testing ( ). Average movement time for all amputees was 242 ms during practice and 272 ms during testing. Motor recruitment synchronization varied across subjects, and amputees with the highest synchronization achieved the fastest movement times. End-point accuracy was independent of movement time. Results suggest that it is feasible for transtibial amputees to generate ballistic control signals using their residual muscles. Future work on volitional control of powered power ankle prostheses might consider anticipatory postural control based on ballistic-like residual

The Effect of Carrier Properties on the Ballistic Processing of Sn-0.7 Cu Thick Films

Science.gov (United States)

Hille, David M.

The need for metallic films has increased since the creation of electronic components. The continued miniaturization of systems and components has led to a greater demand for both thick and thin films, especially in the technology field. Computers, hand held devices, and solar cells are a few of the multitudes of uses for these films. This thesis investigates a novel additive manufacturing process known as Ballistic Manufacturing (BM), invented at the Advanced Materials Processing Lab (AMPL) at San Diego State University. Lead free solder (Tin (Sn)-0.7%Copper (Cu)) was chosen as the testing material due to its low melting temperature. The effects of varying thermal conductivity via the change in carrier material type, the effect of raising substrate temperature, and surface finish differences were investigated. An increase in thermal conductivity resulted in an increase in film thickness and decrease in cell size. As substrate temperature was raised, film thickness decreased, while cell size decreased. Surface finish provided a proof of concept to the transfer of substrate features to the resultant film surface. Evaluation of dendritic microstructures led to relative cooling rates reflective of changes in parameters. The mechanical behavior was also investigated using tensile tests to determine stress-stain relationships and measure elastic modulus. With the current work of this thesis, and previous work by Cavero and Stewart, Ballistic Manufacturing is proven to be an alternative method in the production of metallic films.

MODELING THE FLIGHT TRAJECTORY OF OPERATIONAL-TACTICAL BALLISTIC MISSILES

Directory of Open Access Journals (Sweden)

I. V. Filipchenko

2018-01-01

Full Text Available The article gives the basic approaches to updating the systems of combat operations modeling in the part of enemy missile attack simulation taking into account the possibility of tactical ballistic missile maneuvering during the flight. The results of simulation of combat tactical missile defense operations are given. 

Contemporary management of maxillofacial ballistic trauma.

Science.gov (United States)

Breeze, J; Tong, D; Gibbons, A

2017-09-01

Ballistic maxillofacial trauma in the UK is fortunately relatively rare, and generally involves low velocity handguns and shotguns. Civilian terrorist events have, however, shown that all maxillofacial surgeons need to understand how to treat injuries from improvised explosive devices. Maxillofacial surgeons in the UK have also been responsible for the management of soldiers evacuated from Iraq and Afghanistan, and in this review we describe the newer types of treatment that have evolved from these conflicts, particularly that of damage-control maxillofacial surgery. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Comparison of the characteristics of granular propellant movement in interior ballistics based on the interphase drag model

International Nuclear Information System (INIS)

Jang, Jin Sung; Oh, Seok Hawn; Roh, Tae Seong

2014-01-01

Interior ballistics are completed in tens of milliseconds, as are all gun-firing phenomena. Thus, some data cannot be measured directly through experimentation. Therefore, such complex gun-firing phenomena are traditionally clarified by numerical analysis. In the two phase flow of interior ballistics, interphase drag has a strong effect on propellant particle movement. This drag is a momentum sink in the gas phase and a corresponding source of momentum for the solid phase. Previous studies have calculated the drag force on the propellant particles using Ergun's empirical equation, which was developed for a dense bed and relates the drag to the pressure drop through porous media. However, the particulate bed is fluidized in the course of the cycle of interior ballistics, thus indicating that the flow field is ransient with regions of high Reynolds number beyond the range of experimental data. The Ergun equation is examined through a compensation study and calibrated based on the Reynolds number using the numerical method. Moreover, the influence of different drag models on flow behavior and propellant movement in interior ballistics is analyzed.

Skipping Orbits, Traversing Trajectories, and Quantum Ballistic Transport in Microstructures

NARCIS (Netherlands)

Beenakker, C.W.J.; Houten, H. van; Wees, B.J. van

1989-01-01

Three topics of current interest in the study of quantum ballistic transport in a two-dimensional electron gas are discussed, with an emphasis on correspondences between classical trajectories and quantum states in the various experimental geometries. We consider the quantized conductance of point

GAMMASPHERE: Elimination of ballistic deficit by using a quasi-trapezoidal pulse shaper

International Nuclear Information System (INIS)

Goulding, F.S.; Landis, D.A.; Madden, N.; Maier, M.; Yaver, H.

1993-10-01

Gammasphere uses an spherical array of very large (7.2cm dia.) germanium detectors and only high-multiplicity events are studied. To achieve a reasonable coincidence rate, the individual detector channels must handle high rates with minimum pile-up losses. Ten microseconds was chosen as the total processing time for a signal which means that the shaped signal peaks in about 4us. The combination of short pulse shaping and the fluctuating long charge collection times (up to 400ns) in the detectors exaggerates the energy resolution degradation due to ballistic deficit effects. We describe a method of producing a flat-topped pulse with a simple time-invariant network that satisfies GAMMASPHERE requirements and eliminates ballistic deficit effects

Ballistic transport of graphene pnp junctions with embedded local gates

International Nuclear Information System (INIS)

Nam, Seung-Geol; Ki, Dong-Keun; Kim, Youngwook; Kim, Jun Sung; Lee, Hu-Jong; Park, Jong Wan

2011-01-01

We fabricated graphene pnp devices, by embedding pre-defined local gates in an oxidized surface layer of a silicon substrate. With neither deposition of dielectric material on the graphene nor electron-beam irradiation, we obtained high-quality graphene pnp devices without degradation of the carrier mobility even in the local-gate region. The corresponding increased mean free path leads to the observation of ballistic and phase-coherent transport across a local gate 130 nm wide, which is about an order of magnitude wider than reported previously. Furthermore, in our scheme, we demonstrated independent control of the carrier density in the local-gate region, with a conductance map very much distinct from those of top-gated devices. This was caused by the electric field arising from the global back gate being strongly screened by the embedded local gate. Our scheme allows the realization of ideal multipolar graphene junctions with ballistic carrier transport.

Ballistic Aspects of Feasibility for Prospective Satellite Navigation Technologies

Directory of Open Access Journals (Sweden)

L. N. Lysenko

2015-01-01

Full Text Available When modeling the operating processes of ballistics and navigation support it is expedient to make decomposition of the general problem of coordinate-time and navigation support into the typical options of its engineering implementation.As the satellite navigation technologies the paper considers inter-satellite measurement and autonomous navigation mode of differential correction. It also assesses the possibility of their application to improve the accuracy of navigation determinations.Technologies using inter-satellite measurement tools such as GLONASS / GPS equipment, equipment of inter-satellite radio link, astro-optical space based devices are an independent class of navigation technologies.However, each of these options has both advantages and disadvantages that affect the eva luation of the appropriateness and feasibility of their use.The paper separately considers the problem of increasing survivability of space systems and conservation of ground control complex due to introduction of requirements to ensure the independent functioning of spacecraft and application of technologies of ballistics and navigation support, supposing to involve minimum means of automated ground control complex for these purposes.Currently, there is a completely developed theory of autonomous navigation based on astronomical positional gauges, which are used as onboard optical sensors of orientation and stabilization systems.To date, the differential navigation mode is, virtually, the only approach that can allow the olution of tasks in terms of increased accuracy, but with some restrictions.The implementation of differential mode of treatment is carried out through the creation of differential subsystems of the satellite navigation systems. These subsystems are usually divided into wide-range, regional and local ones.Analysis of ballistic aspects to implement discussed navigation technologies allowed us to identify constraints for improving accuracy to define

Ballistic trauma from an exploding electronic cigarette: Case report

Directory of Open Access Journals (Sweden)

Christopher Ban, DMD

2017-09-01

Full Text Available Electronic cigarettes (e-cigarettes first became available in the United States in 2007, and since that time, the number of e-cigarette users in the US has grown to over 2.5 million. During the period from 2010–2013 alone, the percentage of Americans who reported that they had ever used electronic cigarettes more than doubled from 3.3% to 8.5%. This number will continue to grow, as the use of electronic cigarettes as an alternative to smoking and in smoking cessation is being explored by the public and medical professionals alike. This article presents a case report involving a patient who was injured when the electronic cigarette he was smoking exploded in his face, causing a ballistic injury to his maxilla, as well as a series of other associated injuries. There have been several recent reports in the literature of exploding electronic cigarettes. This article presents a case of avulsive injury due to ballistic trauma with associated impaction of the vaporizing device.

Ballistic Limit Equation for Single Wall Titanium

Science.gov (United States)

Ratliff, J. M.; Christiansen, Eric L.; Bryant, C.

2009-01-01

Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified.

Shooting with sound: optimizing an affordable ballistic gelatin recipe in a graded ultrasound phantom education program.

Science.gov (United States)

Tanious, Shariff F; Cline, Jamie; Cavin, Jennifer; Davidson, Nathan; Coleman, J Keegan; Goodmurphy, Craig W

2015-06-01

The goal of this study was to investigate the durability and longevity of gelatin formulas for the production of staged ultrasound phantoms for education. Gelatin phantoms were prepared from Knox gelatin (Kraft Foods, Northfield, IL) and a standard 10%-by-mass ordinance gelatin solution. Phantoms were durability tested by compressing to a 2-cm depth until cracking was visible. Additionally, 16 containers with varying combinations of phenol, container type, and storage location were tested for longevity against desiccation and molding. Once formulation was determined, 4 stages of phantoms from novice to clinically relevant were poured, and clinicians with ultrasound training ranked them on a 7-point Likert scale based on task difficulty, phantom suitability, and fidelity. On durability testing, the ballistic gelatin outperformed the Knox gelatin by more than 200 compressions. On longevity testing, gelatin with a 0.5% phenol concentration stored with a lid and refrigeration lasted longest, whereas containers without a lid had desiccation within 1 month, and those without phenol became moldy within 6 weeks. Ballistic gelatin was more expensive when buying in small quantities but was 7.4% less expensive when buying in bulk. The staged phantoms were deemed suitable for training, but clinicians did not consistently rank the phantoms in the intended order of 1 to 4 (44%). Refrigerated and sealed ballistic gelatin with phenol was a cost-effective method for creating in-house staged ultrasound phantoms suitable for large-scale ultrasound educational training needs. Clinician ranking of phantoms may be influenced by current training methods that favor biological tissue scanning as easier. © 2015 by the American Institute of Ultrasound in Medicine.

The influence of magnetic field on ballistic performance of aramid fibre and ultrahigh molecular weight polyethylene

International Nuclear Information System (INIS)

Wong, Y.C.; Ruan, D.; Sesso, M.L.

2014-01-01

Highlights: • Ballistic tests conducted on Kevlar and UHMWPE within a magnetic field. • Repulsion force created by opposing magnet poles reduced the impact momentum. • High speed camera images showed no perforation on Kevlar due to magnetic field. • Standoff distance between magnets has an effect on the repulsion force. - Abstract: An innovative method is introduced here whereby using two sets of arrays of rare earth magnets aligned opposite each other in order to create a repulsion force owing to the like poles when facing close to each other. Ballistic test samples of aramid fibre (Kevlar K29) and ultrahigh molecular weight polyethylene (UHMWPE) were sandwiched by two sets of opposing magnets. Ballistic test was conducted using a gas gun with a 7.62 mm diameter projectile at a velocity ranging from 160 to 220 m/s. High speed camera was used to capture the ballistics testing and it shows that the magnetic repulsion force created by the opposing rare earth magnets managed to suppress the projectile from advancing into the front face of the aramid fibre. Similarly, when magnets were used, the UHMWPE sample shows the projectile perforated through the first few sheets and finally rested on the last sheet showing partial perforation

Projectile penetration into ballistic gelatin.

Science.gov (United States)

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 (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. © 2013 Published by Elsevier Ltd.

Investigation of short and ballistic coupling in vertical NbSe2 - graphene - NbSe2 Josephson junctions

Science.gov (United States)

Kim, Minsoo; Park, Geon-Hyoung; Yi, Jongyoon; Lee, Jae Hyeong; Park, Jinho; Lee, Hu-Jong

2H-NbSe2 is a layered two-dimensional superconducting material, which can be constructed into a van der Waals heterostructure with versatile functionality. Here we fabricated a vertically stacked NbSe2 - graphene - NbSe2 heterostructure by the dry transfer technique, where defect-free contact via van der Waals force provides the high interfacial transparency. Insertion of an atomically thin graphene layer between two NbSe2 flakes ensures the formation of highly coherent proximity Josephson coupling. Observed temperature dependence of the junction critical current (Ic) and large value of IcRn product (as large as 2.3ΔNbSe 2) reveal the short and ballistic Josephson coupling characteristics. Large junction critical current density of 104 A/cm2, multiple Andreev reflection in the subgap structure of the differential conductance, and magnetic field modulation of Ic also suggest the strong Josephson coupling via the graphene layer.

Narrow electron injector for ballistic electron spectroscopy

International Nuclear Information System (INIS)

Kast, M.; Pacher, C.; Strasser, G.; Gornik, E.

2001-01-01

A three-terminal hot electron transistor is used to measure the normal energy distribution of ballistic electrons generated by an electron injector utilizing an improved injector design. A triple barrier resonant tunneling diode with a rectangular transmission function acts as a narrow (1 meV) energy filter. An asymmetric energy distribution with its maximum on the high-energy side with a full width at half maximum of ΔE inj =10 meV is derived. [copyright] 2001 American Institute of Physics

Spin Seebeck effect and ballistic transport of quasi-acoustic magnons in room-temperature yttrium iron garnet films

Science.gov (United States)

Noack, Timo B.; Musiienko-Shmarova, Halyna Yu; Langner, Thomas; Heussner, Frank; Lauer, Viktor; Heinz, Björn; Bozhko, Dmytro A.; Vasyuchka, Vitaliy I.; Pomyalov, Anna; L’vov, Victor S.; Hillebrands, Burkard; Serga, Alexander A.

2018-06-01

We studied the transient behavior of the spin current generated by the longitudinal spin Seebeck effect (LSSE) in a set of platinum-coated yttrium iron garnet (YIG) films of different thicknesses. The LSSE was induced by means of pulsed microwave heating of the Pt layer and the spin currents were measured electrically using the inverse spin Hall effect in the same layer. We demonstrate that the time evolution of the LSSE is determined by the evolution of the thermal gradient triggering the flux of thermal magnons in the vicinity of the YIG/Pt interface. These magnons move ballistically within the YIG film with a constant group velocity, while their number decays exponentially within an effective propagation length. The ballistic flight of the magnons with energies above 20 K is a result of their almost linear dispersion law, similar to that of acoustic phonons. By fitting the time-dependent LSSE signal for different film thicknesses varying by almost an order of magnitude, we found that the effective propagation length is practically independent of the YIG film thickness. We consider this fact as strong support of a ballistic transport scenario—the ballistic propagation of quasi-acoustic magnons in room temperature YIG.

Relationships Between Potentiation Effects After Ballistic Half-Squats and Bilateral Symmetry.

Science.gov (United States)

Suchomel, Timothy J; Sato, Kimitake; DeWeese, Brad H; Ebben, William P; Stone, Michael H

2016-05-01

The purposes of this study were to examine the effect of ballistic concentric-only half-squats (COHS) on subsequent squat-jump (SJ) performances at various rest intervals and to examine the relationships between changes in SJ performance and bilateral symmetry at peak performance. Thirteen resistance-trained men performed an SJ immediately and every minute up to 10 min on dual force plates after 2 ballistic COHS repetitions at 90% of their 1-repetition-maximum COHS. SJ peak force, peak power, net impulse, and rate of force development (RFD) were compared using a series of 1-way repeated-measures ANOVAs. The percent change in performance at which peak performance occurred for each variable was correlated with the symmetry index scores at the corresponding time point using Pearson correlation coefficients. Statistical differences in peak power (P = .031) existed between rest intervals; however, no statistically significant pairwise comparisons were present (P > .05). No statistical differences in peak force (P = .201), net impulse (P = .064), and RFD (P = .477) were present between rest intervals. The relationships between changes in SJ performance and bilateral symmetry after the rest interval that produced the greatest performance for peak force (r = .300, P = .319), peak power (r = -.041, P = .894), net impulse (r = -.028, P = .927), and RFD (r = -.434, P = .138) were not statistically significant. Ballistic COHS may enhance SJ performance; however, the changes in performance were not related to bilateral symmetry.

Ballistic V50 Evaluation of TIMET Ti108

Science.gov (United States)

2018-02-01

threat by 1 m/s. Future studies or adjustments to the chemistry of the Ti108 can be conducted to optimize ballistic performance. 15. SUBJECT TERMS...10 Fig. A-2 30-mm APDS overall back of plate .................................................... 10 List of Tables Table 1 Chemistry of Ti108...performance of different titanium alloys. Conventional Ti-6Al-4V is commonly used in aerospace frames and engine components, but has difficulty passing

Dual-hemisphere transcranial direct current stimulation over primary motor cortex enhances consolidation of a ballistic thumb movement.

Science.gov (United States)

Koyama, Soichiro; Tanaka, Satoshi; Tanabe, Shigeo; Sadato, Norihiro

2015-02-19

Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates motor performance and learning. Previous studies have shown that tDCS over the primary motor cortex (M1) can facilitate consolidation of various motor skills. However, the effect of tDCS on consolidation of newly learned ballistic movements remains unknown. The present study tested the hypothesis that tDCS over M1 enhances consolidation of ballistic thumb movements in healthy adults. Twenty-eight healthy subjects participated in an experiment with a single-blind, sham-controlled, between-group design. Fourteen subjects practiced a ballistic movement with their left thumb during dual-hemisphere tDCS. Subjects received 1mA anodal tDCS over the contralateral M1 and 1mA cathodal tDCS over the ipsilateral M1 for 25min during the training session. The remaining 14 subjects underwent identical training sessions, except that dual-hemisphere tDCS was applied for only the first 15s (sham group). All subjects performed the task again at 1h and 24h later. Primary measurements examined improvement in peak acceleration of the ballistic thumb movement at 1h and 24h after stimulation. Improved peak acceleration was significantly greater in the tDCS group (144.2±15.1%) than in the sham group (98.7±9.1%) (Pballistic thumb movement in healthy adults. Dual-hemisphere tDCS over M1 may be useful to improve elemental motor behaviors, such as ballistic movements, in patients with subcortical strokes. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Function-Oriented Material Design of Joints for Advance Armors Under Ballistic Impact

National Research Council Canada - National Science Library

Ma, Zheng-Dong; Wang, Hui; Raju, Basavaraju

2004-01-01

The objective of this research is to develop a system of software tools based on a new design methodology for the efficient composite armor structural design under ballistic impact loading conditions...

Formal Specification and Run-time Monitoring Within the Ballistic Missile Defense Project

National Research Council Canada - National Science Library

Caffall, Dale S; Cook, Thomas; Drusinsky, Doron; Michael, James B; Shing, Man-Tak; Sklavounos, Nicholas

2005-01-01

.... Ballistic Missile Defense Advanced Battle Manager (ABM) project in an effort that is amongst the most comprehensive application of formal methods to a large-scale safety-critical software application ever reported...

Inelastic and ballistic processes resulting from CsF--Ar collisions

International Nuclear Information System (INIS)

Sharma, R.D.; Sindoni, J.M.

1993-01-01

This paper continues the study of inelastic and ballistic collisions for the CsF--Ar system using the impulse approximation (IA). The IA expresses the atom--diatom potential as the sum of the two atom--atom potentials. The atom--atom interaction is approximated by a hard core potential, and the laboratory differential cross sections are calculated for an initial relative translational energy of 1.0 eV as a function of the laboratory recoil velocity of CsF. The calculated differential cross sections are in excellent agreement with the experimental measurements for all eight laboratory scattering angles for which the data are available. While the calculated results show no significant dependence on the initial relative velocity or on the initial vibrational quantum number of CsF, they do show a systematic variation with the initial rotational quantum number---the ballistic effect is more pronounced than that observed experimentally for initial quantum rotational numbers less than 30 and is not pronounced enough for rotational quantum numbers more than 100. Two mechanisms give rise to the ballistic peak. The first one is dominant when the laboratory scattering angle is equal, or nearly equal, to the laboratory angle of the centroid velocity. This mechanism transfers almost all of the relative translational energy into the internal energy of the diatom and magnifies the center-of-mass (c.m.) differential cross section almost a million times. This is due to a singularity in the Jacobian at very small c.m. recoil velocities, which physically means that a small solid angle in the laboratory frame can collect the signal from all 4π steradians in the c.m. frame

Atom-Probe Tomographic Investigations of a Precipitation-Strengthened HSLA-115 Steel and a Ballistic-Resistant 10 wt. % Ni Steel for Naval Applications

Science.gov (United States)

Jain, Divya

High performance structural materials are needed for Naval applications which require an excellent combination of yield strength, low-temperature impact toughness, ductility, ballistic-resistance, and weldability. This research investigates precipitation-strengthened HSLA-115 steels and ballistic-resistant 10 wt. % Ni steels, which have emerged as promising alternatives to the widely used HSLA-100 steels for Naval applications. HSLA-115 is a Cu-bearing high-strength low-carbon martensitic steel and has been used in the flight deck of the recently built U.S. Navy CVN-78 aircraft carrier. It is typically used in conditions with overaged Cu precipitates, to obtain acceptable impact toughness and ductility at 115 ksi (793 MPa) yield strength. However, overaging of Cu precipitates limits its strength and applications. This research demonstrates that aging at 550 °C facilitates the co-precipitation of sub-nanometer sized M2C carbides and Cu precipitates in high number density (˜1023 m-3) in HSLA-115. 3-D atom-probe tomography (APT) investigation reveals that Cu precipitates form first, followed by the nucleation of M2C carbides, which are co-located with Cu precipitates and are distributed heterogeneously at lath-boundaries and dislocations, indicating heterogeneous nucleation of M2C. Carbon redistribution during quenching (following the austenitization) and subsequent aging at 550 °C is followed using APT. Segregation of C (3-6 at. % C) is observed at martensitic lath-boundaries in the as-quenched and 0.12 h aged conditions. On further aging, C redistributes, forming cementite and M 2C carbides, whose composition and morphology evolves with aging time. Precipitation kinetics of M2C carbides is intertwined with Cu precipitates; temporal evolution of Cu precipitates and M2C carbides is characterized in terms of their mean radii, number densities, and volume fractions and correlated with the bulk mechanical properties. Precipitation of M2C carbides offsets the softening

Separate observation of ballistic and scattered photons in the propagation of short laser pulses through a strongly scattering medium

International Nuclear Information System (INIS)

Tereshchenko, Sergei A; Podgaetskii, Vitalii M; Vorob'ev, Nikolai S; Smirnov, A V

1998-01-01

The conditions are identified for simultaneous observation of the peaks of scattered and unscattered (ballistic) photons in a narrow pulsed laser beam crossing a strongly scattering medium. The experimental results are explained on the basis of a nonstationary two-flux model of radiation transport. An analytic expression is given for the contribution of ballistic photons to the transmitted radiation, as a function of the characteristics of the scattering medium. It is shown that the ballistic photon contribution can be increased by the use of high-contrast substances which alter selectively the absorption and scattering coefficients of the medium. (laser applications and other topics in quantum electronics)

High energy ballistic and fracture comparison between multilayered armor systems using non-woven curaua fabric composites and aramid laminates

Directory of Open Access Journals (Sweden)

Fábio de Oliveira Braga

2017-10-01

Full Text Available For personal protection against high kinetic energy projectiles, multilayered armor systems (MAS are usually the best option. They combine synergistically the properties of different materials such as ceramics, composites and metals. In the present work, ballistic tests were performed to evaluate multilayered armor systems (MAS using curaua non-woven fabric epoxy composites as second layer. A comparison to a MAS using aramid (Kevlar™ fabric laminates was made. The results showed that the curaua non-woven fabric composites are suitable to the high ballistic applications, and are promising substitutes for aramid fabric laminates. Keywords: Composite, Natural fiber, Curaua fiber, Non-woven fabric, Aramid laminate, Ballistic test

Molecular dynamics simulations of ballistic He penetration into W fuzz

NARCIS (Netherlands)

Klaver, T. P. C.; Nordlund, K.; Morgan, T. W.; Westerhof, E.; Thijsse, B. J.; van de Sanden, M. C. M.

2016-01-01

Results are presented of large-scale Molecular Dynamics simulations of low-energy He bombardment of W nanorods, or so-called ‘fuzz’ structures. The goal of these simulations is to see if ballistic He penetration through W fuzz offers a more realistic scenario for how He moves through fuzz layers

Nonlinear electron transport in InAs/AlGaSb three-terminal ballistic junctions

International Nuclear Information System (INIS)

Koyama, M; Inoue, T; Amano, N; Maemoto, T; Sasa, S; Inoue, M

2008-01-01

We have fabricated and characterized an InAs/AlGaSb three-terminal ballistic junction device. The fabricated device exhibited nonlinear electron transport properties because of ballistic motion of electrons in this structure that is comparable to the electron mean free path. When the left branch is biased to a finite voltage Vand the right to a voltage of -V (push-pull fashion), negative voltages appeared at the floating central branch regardless of the polarity of the input voltages. In the case of the central branch grounded in push-pull fashion, the clear current rectification effect also observed in the current flow of the central branch at 4.2K to even at 300K

How to optimize joint theater ballistic missile defense

OpenAIRE

Diehl, Douglas D.

2004-01-01

Approved for public release, distribution is unlimited Many potential adversaries seek, or already have theater ballistic missiles capable of threatening targets of interest to the United States. The U.S. Missile Defense Agency and armed forces are developing and fielding missile interceptors carried by many different platforms, including ships, aircraft, and ground units. Given some exigent threat, the U.S. must decide where to position defensive platforms and how they should engage poten...

Spin-orbit torque in a thin film of the topological insulator Bi2Se3: Crossover from the ballistic to diffusive regime

Science.gov (United States)

Ren, Y. J.; Deng, W. Y.; Geng, H.; Shen, R.; Shao, L. B.; Sheng, L.; Xing, D. Y.

2017-12-01

The spin-orbit torque provides an efficient method for switching the direction of a magnetization by using an electric field. Owing to the spin-orbit coupling, when an electric field is applied, a nonequilibrium spin density is generated, which exerts a torque on the local magnetization. Here, we investigate the spin-orbit torque in a thin film of topological insulator \\text{Bi}2\\text{Se}3 based upon a Boltzmann equation, with proper boundary conditions, which is applicable from the ballistic regime to the diffusive regime. It is shown that due to the spin-momentum interlocking of the electron surface states, the magnitude of the field-like torque is simply in linear proportion to the longitudinal electrical current. For a fixed electric field, the spin-orbit torque is proportional to the sample length in the ballistic limit, and saturates to a constant in the diffusive limit. The dependence of the torque on the magnetization direction and exchange coupling strength is also studied. Our theory may offer useful guidance for experimental investigations of the spin-orbit torque in finite-size systems.

NATO and U.S. Ballistic Missile Defense Programs: Divergent or Convergent Paths?

National Research Council Canada - National Science Library

Toms, Kevin E

2008-01-01

...) information network to support the Theater Missile Defense (TMD) capabilities of specific Allies for the protection of forward deployed troops, and studies of the feasibility and political-military implications of Ballistic Missile Defense (BMD...

Dynamic material characterization by combining ballistic testing and an engineering model

NARCIS (Netherlands)

Carton, E.P.; Roebroeks, G.H.J.J.; Wal, R. van der

2013-01-01

At TNO several energy-based engineering models have been created for various failure mechanism occurring in ballistic testing of materials, like ductile hole growth, denting, plugging, etc. Such models are also under development for ceramic and fiberbased materials (fabrics). As the models are

Optical detection of ballistic electrons injected by a scanning-tunneling microscope

NARCIS (Netherlands)

Kemerink, M.; Sauthoff, K.; Koenraad, P.M.; Gerritsen, J.W.; Kempen, van H.; Wolter, J.H.

2001-01-01

We demonstrate a spectroscopic technique which is based on ballistic injection of minority carriers from the tip of a scanning-tunneling microscope into a semiconductor heterostructure. By analyzing the resulting electroluminescence spectrum as a function of tip-sample bias, both the injection

North Korea's satellite launch: provocation and ballistic progress

International Nuclear Information System (INIS)

Sitt, Bernard

2013-12-01

North Korea's putting into orbit of a small meteorological satellite using an Unha-3 launcher on the 13 December 2013, a year on from Kim Jong-il's passing, smacks of provocation. The launch of an SLV that is closely related to the Taepodong-2 and that has numerous characteristics in common with a long-range ballistic missile contravened Security Council Resolutions 1695 (2006), 1718 (2006), and 1874 (2009), adopted in response to nuclear and ballistic tests carried out by Pyongyang. These resolutions implemented a progressively more strenuous regime of sanctions, which cannot fail to have marked the North Korean dictatorship, at least in economic and financial terms. The provisional successes and failures of the Six-party talks, mediated by China, which have been at a dead-end since 2009 bear witness to the unpredictability of the North's reactions. Pyongyang's double-agenda is, nonetheless, relatively easily to discern. Firstly, with this successful launch, North Korea has redeemed the failure of the first Unha-3 launch on the 13 April 2012, at the same time as Kim Jong-un took power and the country was celebrating the centenary of the birth of its founder, Kim Il-sung. This success evidently helps to bolster both the young leader's prestige on the domestic front and his sway over the army. Simultaneously, and beyond any symbolic value, North Korea's development of long-range ballistic capabilities constitutes veritable progress, on the back of a series of failures since 2006. Naturally, the reliability of the Unha-3 launcher (or of an improved Taepodong-2) is by no means guaranteed. Moreover, its payload is limited, since it can presently only launch small satellites, and thus well below the capacity needed to carry a nuclear weapon. If this is indeed North Korea's objective in years to come, it will need to make considerable technological progress, including the development of sufficiently small nuclear devices, which would necessitate further nuclear tests. In

Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

Science.gov (United States)

Lefebvre, M.; Boussu, F.; Coutellier, D.; Vallee, D.

2012-08-01

The armour of vehicles against conventional threats is mainly composed with steel or aluminium panels. Efficient heavy solutions exist, but the involved industries require new lightweight structures. Moreover, unconventional threats as IEDs (Improvised Explosive Devices) may cause severe damages on these structural and protective panel solutions. Thus, combination of aluminium or steel plates with textile composite structures used as a backing, leads to the mass reduction and better performance under delamination behaviour against these new threats. This paper is a part of a study dealing with the impact behaviour of three warp interlocks weaving structures under Fragment Simulating Projectile (FSP) impact. During this research, several parameters has being studied as the influence of the yarns insertions [1-4], the degradation of the yarns during the weaving process [5-7], and the influence of the resin rate on the ballistic behaviour. The resin rate inside composite materials is dependant on the final application. In ballistic protection, we need to control the resin rate in order to have a deformable structure in order to absorb the maximum of energy. However, with the warp interlocks weaving structure, the yarns insertions induce empty spaces between the yarns where the resin takes place without being evacuated. The resin rate inside the warp interlocks structures is in the most of cases less than 50%, which lead to have brittle and hard material during the impact. Contrary to interlocks structures, the existing protection based on prepreg structure have a high fibres ratio around 88% of weight. That leads to have the best ballistic properties during the impact and good deformability of the structure. The aim of this paper is to evaluate the influence of the resin rate on the ballistic results of the composites materials. For that, we have chosen two kinds of warp interlocks fabrics which were infused with epoxy resin following two processes. The first is a

High-speed Imaging of Global Surface Temperature Distributions on Hypersonic Ballistic-Range Projectiles

Science.gov (United States)

Wilder, Michael C.; Reda, Daniel C.

2004-01-01

The NASA-Ames ballistic range provides a unique capability for aerothermodynamic testing of configurations in hypersonic, real-gas, free-flight environments. The facility can closely simulate conditions at any point along practically any trajectory of interest experienced by a spacecraft entering an atmosphere. Sub-scale models of blunt atmospheric entry vehicles are accelerated by a two-stage light-gas gun to speeds as high as 20 times the speed of sound to fly ballistic trajectories through an 24 m long vacuum-rated test section. The test-section pressure (effective altitude), the launch velocity of the model (flight Mach number), and the test-section working gas (planetary atmosphere) are independently variable. The model travels at hypersonic speeds through a quiescent test gas, creating a strong bow-shock wave and real-gas effects that closely match conditions achieved during actual atmospheric entry. The challenge with ballistic range experiments is to obtain quantitative surface measurements from a model traveling at hypersonic speeds. The models are relatively small (less than 3.8 cm in diameter), which limits the spatial resolution possible with surface mounted sensors. Furthermore, since the model is in flight, surface-mounted sensors require some form of on-board telemetry, which must survive the massive acceleration loads experienced during launch (up to 500,000 gravities). Finally, the model and any on-board instrumentation will be destroyed at the terminal wall of the range. For these reasons, optical measurement techniques are the most practical means of acquiring data. High-speed thermal imaging has been employed in the Ames ballistic range to measure global surface temperature distributions and to visualize the onset of transition to turbulent-flow on the forward regions of hypersonic blunt bodies. Both visible wavelength and infrared high-speed cameras are in use. The visible wavelength cameras are intensified CCD imagers capable of integration

Ballistic Missile Defense in the European Theater: Political, Military and Technical Considerations

National Research Council Canada - National Science Library

Terstegge, Stephen D

2007-01-01

... that threatens the homeland of the United States. Therefore, the United States faces the complex security challenge of emplacing ballistic missile defense assets on European soil in the very near-term to mitigate this threat...

Comparison of the ballistic contractile responses generated during microstimulation of single human motor axons with brief irregular and regular stimuli.

Science.gov (United States)

Leitch, Michael; Macefield, Vaughan G

2017-08-01

Ballistic contractions are induced by brief, high-frequency (60-100 Hz) trains of action potentials in motor axons. During ramp voluntary contractions, human motoneurons exhibit significant discharge variability of ∼20% and have been shown to be advantageous to the neuromuscular system. We hypothesized that ballistic contractions incorporating discharge variability would generate greater isometric forces than regular trains with zero variability. High-impedance tungsten microelectrodes were inserted into human fibular nerve, and single motor axons were stimulated with both irregular and constant-frequency stimuli at mean frequencies ranging from 57.8 to 68.9 Hz. Irregular trains generated significantly greater isometric peak forces than regular trains over identical mean frequencies. The high forces generated by ballistic contractions are not based solely on high frequencies, but rather a combination of high firing rates and discharge irregularity. It appears that irregular ballistic trains take advantage of the "catchlike property" of muscle, allowing augmentation of force. Muscle Nerve 56: 292-297, 2017. © 2016 Wiley Periodicals, Inc.

Aerodynamic heating of ballistic missile including the effects of gravity

Indian Academy of Sciences (India)

The aerodynamic heating of a ballistic missile due to only convection is analysed taking into consideration the effects of gravity. The amount of heat transferred to the wetted area and to the nose region has been separately determined, unlike A Miele's treatise without consideration of gravity. The peak heating ratesto the ...

Aerodynamic heating of ballistic missile including the effects of gravity

Indian Academy of Sciences (India)

Abstract. The aerodynamic heating of a ballistic missile due to only convection is analysed taking into consideration the effects of gravity. The amount of heat transferred to the wetted area and to the nose region has been separately determined, unlike A Miele's treatise without consideration of gravity. The peak heating rates ...

Effect of micro lesions of the basal ganglia on ballistic movements in patients with deep brain stimulation.

Science.gov (United States)

Singh, Arun; Mehrkens, Jan H; Bötzel, Kai

2012-03-15

Bradykinesia and hypokinesia are the prominent symptoms of substantia nigra degeneration in Parkinson's disease (PD). In segmental dystonia, movements of not affected limbs are not impaired. Here we studied the impact of the mere implantation of stimulation electrodes on the performance of fast movements in these two groups. We investigated 9 PD patients with subthalamic electrodes and 9 patients with segmental dystonia with electrodes in the globus pallidus internum. Patients were studied on the first postoperative day without electrical stimulation of the electrodes. Subjects had to perform boxing movements with either touching the target or stopping the fist in front of the target. PD subjects performed significantly faster movements in the touch-task only as compared to dystonic patients. No difference was seen in the stopping task. In conclusion, our findings suggest that a small subthalamic lesion in individuals with PD specifically reverses bradykinesia during simple ballistic movements (touch) but not during complex ones requiring more pre-programming (no-touch paradigm). Copyright © 2011 Elsevier B.V. All rights reserved.

Gate tuneable beamsplitter in ballistic graphene

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-21

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

Going ballistic: Graphene hot electron transistors

Science.gov (United States)

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

2015-12-01

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

Adaptations in athletic performance after ballistic power versus strength training.

Science.gov (United States)

Cormie, Prue; McGuigan, Michael R; Newton, Robert U

2010-08-01

To determine whether the magnitude of improvement in athletic performance and the mechanisms driving these adaptations differ in relatively weak individuals exposed to either ballistic power training or heavy strength training. Relatively weak men (n = 24) who could perform the back squat with proficient technique were randomized into three groups: strength training (n = 8; ST), power training (n = 8; PT), or control (n = 8). Training involved three sessions per week for 10 wk in which subjects performed back squats with 75%-90% of one-repetition maximum (1RM; ST) or maximal-effort jump squats with 0%-30% 1RM (PT). Jump and sprint performances were assessed as well as measures of the force-velocity relationship, jumping mechanics, muscle architecture, and neural drive. Both experimental groups showed significant (P training with no significant between-group differences evident in either jump (peak power: ST = 17.7% +/- 9.3%, PT = 17.6% +/- 4.5%) or sprint performance (40-m sprint: ST = 2.2% +/- 1.9%, PT = 3.6% +/- 2.3%). ST also displayed a significant increase in maximal strength that was significantly greater than the PT group (squat 1RM: ST = 31.2% +/- 11.3%, PT = 4.5% +/- 7.1%). The mechanisms driving these improvements included significant (P force-velocity relationship, jump mechanics, muscle architecture, and neural activation that showed a degree of specificity to the different training stimuli. Improvements in athletic performance were similar in relatively weak individuals exposed to either ballistic power training or heavy strength training for 10 wk. These performance improvements were mediated through neuromuscular adaptations specific to the training stimulus. The ability of strength training to render similar short-term improvements in athletic performance as ballistic power training, coupled with the potential long-term benefits of improved maximal strength, makes strength training a more effective training modality for relatively weak individuals.

MIRROR AND POINT SYMMETRIES IN A BALLISTIC JET FROM A BINARY SYSTEM

International Nuclear Information System (INIS)

Raga, A. C.; Esquivel, A.; Velazquez, P. F.; Haro-Corzo, S.; RodrIguez-Gonzalez, A.; Canto, J.; Riera, A.

2009-01-01

Models of accretion disks around a star in a binary system predict that the disk will have a retrograde precession with a period a factor of ∼10 times the orbital period. If the star+disk system ejects a bipolar outflow, this outflow will be subject to the effects of both the orbital motion and the precession. We present an analytic, ballistic model and a three-dimensional gasdynamical simulation of a bipolar outflow from a source in a circular orbit, and with a precessing outflow axis. We find that this combination results in a jet/counterjet system with a small spatial scale, reflection-symmetric spiral (resulting from the orbital motion) and a larger-scale, point-symmetric spiral (resulting from the longer period precession). These results provide interesting possibilities for modeling specific Herbig-Haro jets and bipolar planetary nebulae.

Analytical model for a cooperative ballistic deposition in one dimension

Science.gov (United States)

Hassan, M. Kamrul; Wessel, Niels; Kurths, Jürgen

2003-06-01

We formulate a model for a cooperative ballistic deposition (CBD) process whereby the incoming particles are correlated with those already adsorbed via attractive force. The strength of the correlation is controlled by a tunable parameter a that interpolates the classical car parking problem at a=0, the ballistic deposition at a=1, and the CBD model at a>1. The effects of the correlation in the CBD model are as follows. The jamming coverage q(a) increases with the strength of attraction a due to an ever-increasing tendency of cluster formation. The system almost reaches the closest packing structure as a→∞ but never forms a percolating cluster, which is typical of one-dimensional systems. In the large a regime, the mean cluster size k increases as a1/2. Furthermore, the asymptotic approach towards the closest packing is purely algebraic both with a as q(∞)-q(a)˜a-1/2 and with k as q(∞)-q(k)˜k-1, where q(∞)≃1.

Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

Science.gov (United States)

Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

Examples of the nonlinear dynamics of ballistic capture and escape in the earth-moon system

Science.gov (United States)

Belbruno, Edward A.

1990-01-01

An example of a trajectory is given which is initially captured in an elliptic resonant orbit about the earth and then ballistically escapes the earth-moon system. This is demonstrated by a numerical example in three-dimensions using a planetary ephemeris. Another example shows a mechanism of how an elliptic orbit about the earth can increase its energy by performing a complex nonlinear transition to an elliptic orbit of a larger semi-major axis. Capture is also considered. An application of ballistic capture at the moon via an unstable periodic orbit using the four-body sun-earth-moon-S/C interaction is described.

Civilian casualties of Iraqi ballistic missile attack to

Directory of Open Access Journals (Sweden)

Khaji Ali

2012-06-01

Full Text Available 【Abstract】Objective: To determine the pattern of causalities of Iraqi ballistic missile attacks on Tehran, the capital of Iran, during Iraq-Iran war. Methods: Data were extracted from the Army Staff Headquarters based on daily reports of Iranian army units during the war. Results: During 52 days, Tehran was stroked by 118 Al-Hussein missiles (a modified version of Scud missile. Eighty-six missiles landed in populated areas. During Iraqi missile attacks, 422 civilians died and 1 579 injured (4.9 deaths and 18.3 injuries per missile. During 52 days, 8.1 of the civilians died and 30.4 injured daily. Of the cases that died, 101 persons (24% were excluded due to the lack of information. Among the remainders, 179 (55.8% were male and 142 (44.2% were female. The mean age of the victims was 25.3 years±19.9 years. Our results show that the high accuracy of modified Scud missiles landed in crowded ar-eas is the major cause of high mortality in Tehran. The pres-ence of suitable warning system and shelters could reduce civilian casualties. Conclusion: The awareness and readiness of civilian defense forces, rescue services and all medical facilities for dealing with mass casualties caused by ballistic missile at-tacks are necessary. Key words: Mortality; War; Mass casualty incidents; Wounds and injuries

On the Trajectories of Projectiles Depicted in Early Ballistic Woodcuts

Science.gov (United States)

Stewart, Sean M.

2012-01-01

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

Improving the ballistic immunity of armour steel weldments by plasma transferred arc (PTA) hardfacing

International Nuclear Information System (INIS)

Babu, S.; Balasubramanian, V.; Madhusudhan Reddy, G.; Balasubramanian, T.S.

2010-01-01

This investigation describes about improving the ballistic immunity of armour steel joints which are fabricated by sandwiching of plasma transferred arc (PTA) hardfaced interlayers in between soft austenitic stainless steel (ASS) welds. From the results, the welds with sandwiched interlayer stopped all the projectiles successfully, irrespective of processes used, whereas welds without sandwiched interlayer were failed. In order to know the cause of failure, a detailed metallographic examination was carried out. The variation in microstructure and hardness at various zones of the weld are discussed. For the first time, it was found that the armour steel could be hardfaced by the PTA process with tungsten carbide powder.

Dynamics of ballistically injected latex particles in living human endothelial cells

NARCIS (Netherlands)

Li, Y.; Vanapalli Veera, V.S.A.R.; Vanapalli, Srinivas; Duits, Michael H.G.

2009-01-01

We studied the dynamics of ballistically injected latex particles (BIP) inside endothelial cells, using video particle tracking to measure the mean squared displacement (MSD) as a function of lag time. The MSD shows a plateau at short times and a linear behavior at longer times, indicating that the

Debris Examination Using Ballistic and Radar Integrated Software

Science.gov (United States)

Griffith, Anthony; Schottel, Matthew; Lee, David; Scully, Robert; Hamilton, Joseph; Kent, Brian; Thomas, Christopher; Benson, Jonathan; Branch, Eric; Hardman, Paul;

Quantum logic gates based on ballistic transport in graphene

Energy Technology Data Exchange (ETDEWEB)

Dragoman, Daniela [Faculty of Physics, University of Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania); Academy of Romanian Scientists, Splaiul Independentei 54, 050094 Bucharest (Romania); Dragoman, Mircea, E-mail: mircea.dragoman@imt.ro [National Institute for Research and Development in Microtechnology (IMT), P.O. Box 38-160, 023573 Bucharest (Romania)

2016-03-07

The paper presents various configurations for the implementation of graphene-based Hadamard, C-phase, controlled-NOT, and Toffoli gates working at room temperature. These logic gates, essential for any quantum computing algorithm, involve ballistic graphene devices for qubit generation and processing and can be fabricated using existing nanolithographical techniques. All quantum gate configurations are based on the very large mean-free-paths of carriers in graphene at room temperature.

Production and Mechanical Characterization of Ballistic Thermoplastic Composite Materials

OpenAIRE

D. Korsacilar; C. Atas

2014-01-01

In this study, first thermoplastic composite materials /plates that have high ballistic impact resistance were produced. For this purpose, the thermoplastic prepreg and the vacuum bagging technique were used to produce a composite material. Thermoplastic prepregs (resin-impregnated fiber) that are supplied ready to be used, namely high-density polyethylene (HDPE) was chosen as matrix and unidirectional glass fiber was used as reinforcement. In order to compare the fiber c...

Conventional Prompt Global Strike and Long-Range Ballistic Missiles: Background and Issues

Science.gov (United States)

2016-02-24

FY2008, Congress rejected the requested funding for this program, but the Navy has continued to consider the possibility of deploying intermediate ...10 Submarine-Launched Intermediate -Range Global Strike .................................................. 11 Air Force Programs...Missiles............................................................................ 36 Submarine-Launched Intermediate -Range Ballistic Missiles

In-flight dynamics of volcanic ballistic projectiles

Science.gov (United States)

Taddeucci, J.; Alatorre-Ibargüengoitia, M. A.; Cruz-Vázquez, O.; Del Bello, E.; Scarlato, P.; Ricci, T.

2017-09-01

Centimeter to meter-sized volcanic ballistic projectiles from explosive eruptions jeopardize people and properties kilometers from the volcano, but they also provide information about the past eruptions. Traditionally, projectile trajectory is modeled using simplified ballistic theory, accounting for gravity and drag forces only and assuming simply shaped projectiles free moving through air. Recently, collisions between projectiles and interactions with plumes are starting to be considered. Besides theory, experimental studies and field mapping have so far dominated volcanic projectile research, with only limited observations. High-speed, high-definition imaging now offers a new spatial and temporal scale of observation that we use to illuminate projectile dynamics. In-flight collisions commonly affect the size, shape, trajectory, and rotation of projectiles according to both projectile nature (ductile bomb versus brittle block) and the location and timing of collisions. These, in turn, are controlled by ejection pulses occurring at the vent. In-flight tearing and fragmentation characterize large bombs, which often break on landing, both factors concurring to decrease the average grain size of the resulting deposits. Complex rotation and spinning are ubiquitous features of projectiles, and the related Magnus effect may deviate projectile trajectory by tens of degrees. A new relationship is derived, linking projectile velocity and size with the size of the resulting impact crater. Finally, apparent drag coefficient values, obtained for selected projectiles, mostly range from 1 to 7, higher than expected, reflecting complex projectile dynamics. These new perspectives will impact projectile hazard mitigation and the interpretation of projectile deposits from past eruptions, both on Earth and on other planets.

Muscle activity during leg strengthening exercise using free weights and elastic resistance: effects of ballistic vs controlled contractions.

Science.gov (United States)

Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Aagaard, Per; Andersen, Lars L

2013-02-01

The present study's aim was to evaluate muscle activity during leg exercises using elastic vs. isoinertial resistance at different exertion and loading levels, respectively. Twenty-four women and eighteen men aged 26-67 years volunteered to participate in the experiment. Electromyographic (EMG) activity was recorded in nine muscles during a standardized forward lunge movement performed with dumbbells and elastic bands during (1) ballistic vs. controlled exertion, and (2) at low, medium and high loads (33%, 66% and 100% of 10 RM, respectively). The recorded EMG signals were normalized to MVC EMG. Knee joint angle was measured using electronic inclinometers. The following results were obtained. Loading intensity affected EMG amplitude in the order: lowBallistic contractions always produced greater EMG activity than slow controlled contractions, and for most muscles ballistic contractions with medium load showed similar EMG amplitude as controlled contractions with high load. At flexed knee joint positions with elastic resistance, quadriceps and gluteus EMG amplitude during medium-load ballistic contractions exceeded that recorded during high-load controlled contractions. Quadriceps and gluteus EMG amplitude increased at flexed knee positions. In contrast, hamstrings EMG amplitude remained constant throughout ROM during dumbbell lunge, but increased at more extended knee joint positions during lunges using elastic resistance. Based on these results, it can be concluded that lunges performed using medium-load ballistic muscle contractions may induce similar or even higher leg muscle activity than lunges using high-load slow-speed contractions. Consequently, lunges using elastic resistance appear to be equally effective in inducing high leg muscle activity as traditional lunges using isoinertial resistance. Copyright © 2012 Elsevier B.V. All rights reserved.

Potentiation: Effect of Ballistic and Heavy Exercise on Vertical Jump Performance.

Science.gov (United States)

Hester, Garrett M; Pope, Zachary K; Sellers, John H; Thiele, Ryan M; DeFreitas, Jason M

2017-03-01

Hester, GM, Pope, ZK, Sellers, JH, Thiele, RM, and DeFreitas, JM. Potentiation: Effect of ballistic and heavy exercise on vertical jump performance. J Strength Cond Res 31(3): 660-666, 2017-The purpose of this study was to compare the acute effects of heavy and ballistic conditioning protocols on vertical jump performance in resistance-trained men. Fourteen resistance-trained men (mean ± SD: age = 22 ± 2.1 years, body mass = 86.29 ± 9.95 kg, and height = 175.39 ± 9.34 cm) with an average relative full squat of 2.02 ± 0.28 times their body mass participated in this study. In randomized, counterbalanced order, subjects performed two countermovement vertical jumps before and 1, 3, 5, and 10 minutes after either performing 10 rapid jump squats or 5 heavy back squats. The back squat protocol consisted of 5 repetitions at 80% one repetition maximum (1RM), whereas the jump squat protocol consisted of 10 repetitions at 20% 1RM. Peak jump height (in centimeters) using a jump mat, along with power output (in Watts) and velocity (in meters per second) through a linear transducer, was recorded for each time interval. There was no significant condition × time interaction for any of the dependent variables (p = 0.066-0.127). In addition, there was no main effect for condition for any of the dependent variables (p = 0.457-0.899). Neither the ballistic nor heavy protocol used in this study enhanced vertical jump performance at any recovery interval. The use of these protocols in resistance-trained men to produce postactivation potentiation is not recommended.

Room-Temperature Quantum Ballistic Transport in Monolithic Ultrascaled Al-Ge-Al Nanowire Heterostructures.

Science.gov (United States)

Sistani, Masiar; Staudinger, Philipp; Greil, Johannes; Holzbauer, Martin; Detz, Hermann; Bertagnolli, Emmerich; Lugstein, Alois

2017-08-09

Conductance quantization at room temperature is a key requirement for the utilizing of ballistic transport for, e.g., high-performance, low-power dissipating transistors operating at the upper limit of "on"-state conductance or multivalued logic gates. So far, studying conductance quantization has been restricted to high-mobility materials at ultralow temperatures and requires sophisticated nanostructure formation techniques and precise lithography for contact formation. Utilizing a thermally induced exchange reaction between single-crystalline Ge nanowires and Al pads, we achieved monolithic Al-Ge-Al NW heterostructures with ultrasmall Ge segments contacted by self-aligned quasi one-dimensional crystalline Al leads. By integration in electrostatically modulated back-gated field-effect transistors, we demonstrate the first experimental observation of room temperature quantum ballistic transport in Ge, favorable for integration in complementary metal-oxide-semiconductor platform technology.

Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

Directory of Open Access Journals (Sweden)

Coutellier D.

2012-08-01

Full Text Available The armour of vehicles against conventional threats is mainly composed with steel or aluminium panels. Efficient heavy solutions exist, but the involved industries require new lightweight structures. Moreover, unconventional threats as IEDs (Improvised Explosive Devices may cause severe damages on these structural and protective panel solutions. Thus, combination of aluminium or steel plates with textile composite structures used as a backing, leads to the mass reduction and better performance under delamination behaviour against these new threats. This paper is a part of a study dealing with the impact behaviour of three warp interlocks weaving structures under Fragment Simulating Projectile (FSP impact. During this research, several parameters has being studied as the influence of the yarns insertions [1–4], the degradation of the yarns during the weaving process [5–7], and the influence of the resin rate on the ballistic behaviour. The resin rate inside composite materials is dependant on the final application. In ballistic protection, we need to control the resin rate in order to have a deformable structure in order to absorb the maximum of energy. However, with the warp interlocks weaving structure, the yarns insertions induce empty spaces between the yarns where the resin takes place without being evacuated. The resin rate inside the warp interlocks structures is in the most of cases less than 50%, which lead to have brittle and hard material during the impact. Contrary to interlocks structures, the existing protection based on prepreg structure have a high fibres ratio around 88% of weight. That leads to have the best ballistic properties during the impact and good deformability of the structure. The aim of this paper is to evaluate the influence of the resin rate on the ballistic results of the composites materials. For that, we have chosen two kinds of warp interlocks fabrics which were infused with epoxy resin following two

Theory of spin-polarized transport in ferromagnet-semiconductor structures: Unified description of ballistic and diffusive transport

International Nuclear Information System (INIS)

Lipperheide, R.; Wille, U.

2006-01-01

A theory of spin-polarized electron transport in ferromagnet-semiconductor heterostructures, based on a unified semiclassical description of ballistic and diffusive transport in semiconductors, is outlined. The aim is to provide a framework for studying the interplay of spin relaxation and transport mechanism in spintronic devices. Transport inside the (nondegenerate) semiconductor is described in terms of a thermoballistic current, in which electrons move ballistically in the electric field arising from internal and external electrostatic potentials, and are thermalized at randomly distributed equilibration points. Spin relaxation is allowed to take place during the ballistic motion. For arbitrary potential profile and arbitrary values of the momentum and spin relaxation lengths, an integral equation for a spin transport function determining the spin polarization in the semiconductor is derived. For field-driven transport in a homogeneous semiconductor, the integral equation can be converted into a second-order differential equation that generalizes the spin drift-diffusion equation. The spin polarization in ferromagnet-semiconductor structures is obtained by matching the spin-resolved chemical potentials at the interfaces, with allowance for spin-selective interface resistances. Illustrative examples are considered

Study on Ballistic Absorbing Energy Character of High Performance Polyethylene Needle Felt

Science.gov (United States)

Kailiang, Zhu; Jianqiao, Fu

2017-11-01

The ballistic performance of polyethylene needle felt is tested and the failure morphology after test is also observed. The results showed that when the non-dimensionally non-stressed fibers in polyethylene needles are subjected to high-speed projectile, secondary movement such as stretching and twisting occurs first. This secondary movement is very full, it is the main way of ballistic absorbing energy of the polyethylene needle felt which can avoid the polyethylene fiber short-term rapid heating-up and destroyed. Analysis results show that under normal temperature and humidity conditions, the V50 of 6-layer forded polyethylene needle felt sample is 250m/s. At (450 ± 50) m/s speed range of the target missile, the mean value of the penetrative specific energy absorption for 3-layer forded polyethylene needle felt anti-1.1g simulated projectiles (tapered column) reaches 24.1J·m2/kg.

Development of an Advanced Composite Material Model Suitable for Blast and Ballistic Impact Simulations

National Research Council Canada - National Science Library

Yen, C. F; Cheeseman, B. A

2004-01-01

A robust composite progressive failure model has been successfully developed to account for the strain-rate and pressure dependent behavior of composite materials subjected to high velocity ballistic impact...

The proliferation of ballistic missiles: an aggravating factor of crises

International Nuclear Information System (INIS)

Rousset, Valery

2015-01-01

After a brief recall of the history of the development of ballistic missiles from World War II, the author discusses the various uses of these missiles, on the one hand by major powers, and on the other hand by other countries like Israel, Pakistan and India, and also Egypt and Iraq. He recalls the uses of these missiles during regional conflicts (Scuds by Iraq) and then discusses the issue of proliferation of ballistic missiles. He notices that most of these weapons are present in the arsenal of major powers under the form of intercontinental missiles, intermediate range weapons or theatre weapons. On the Third World side, proliferation concerns short- and medium-range missiles produced from technology transfers or national programmes. Mobile systems are now present in all conflicts (notably Libya, Syria) and are now based on more advanced technologies for propellers as well as for control and guidance systems. In the last part, the author discusses the perspectives associated with these missiles which are a strong offensive weapon, and are also modernised to carry nuclear warheads or multiple warheads. These evolutions could put the western superiority into question again

Shape of scoria cones on Mars: Insights from numerical modeling of ballistic pathways

Czech Academy of Sciences Publication Activity Database

Brož, Petr; Čadek, O.; Hauber, E.; Rossi, A. P.

2014-01-01

Roč. 406, November (2014), s. 14-23 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * explosive volcanism * scoria cone * ballistic pathway Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 4.734, year: 2014

Location of civilian ballistic femoral fracture indicates likelihood of arterial injury.

Science.gov (United States)

Gitajn, Leah; Perdue, Paul; Hardcastle, John; O'Toole, Robert V

2014-10-01

We evaluated whether the location of a ballistic femoral fracture helps predict the presence of arterial injury. We hypothesized that fractures located in the distal third of the femur are associated with a higher rate of arterial injury. We conducted a retrospective review of electronic medical records at our level I trauma centre and found 133 consecutive patients with femoral fractures from civilian gunshots from 2002 to 2007, 14 of whom sustained arterial injury. Fracture extent was measured with computerized viewing software and recorded with a standard technique, calculating proximal, distal, and central locations of the fracture as a function of overall length of the bone. Analyses were conducted with Student's t, Chi-squared, and Fisher's exact tests. The location of any fracture line in the distal third of the femur was associated with increased risk of arterial injury (Pballistic injury is six times more likely to be associated with arterial injury and warrants careful evaluation. Our data show that fracture location can help alert clinicians to possible arterial injury after ballistic femoral fracture. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ballistic delivery of dyes for structural and functional studies of the nervous system

Science.gov (United States)

Gan, Wen-Biao; Grutzendler, Jaime; Wong, Rachel O.; Lichtman, Jeff W.

2010-01-01

This chapter describes a detail protocol for rapid labeling of cells in a variety of preparations by means of particle-mediated ballistic (gene gun) delivery of fluorescent dyes. This method has been used for rapid labeling of cells with either lipid or water-soluble dyes in a variety of preparations. In particular, carbocyanine lipophilic dyes such as DiI have been used to obtain Golgi-like labeling of neurons and glia in fixed and live cell cultures, brain slices, as well as fixed post-mortem human brain. Water-soluble calcium indicators such as calcium green-1 dextran have been used to image calcium dynamics in living brain slices and retinal explants. This ballistic labeling technique is thus useful for studying the structure and function of neurons and glia in both living and fixed specimens. PMID:20147144

The Method of Analysis Derived Coefficients of Database as a New Method of Historical Research (for Example, a Database of Ballistic Parameters of Naval Artillery

Directory of Open Access Journals (Sweden)

Nicholas W. Mitiukov

2015-12-01

Full Text Available In paper there is proposed a new method of historical research, based on analysis of derivatives coefficients of database (for example, the form factor in the database of ballistic data. This method has a much greater protection from subjectivism and direct falsification, compared with the analysis obtained directly from the source of the numerical series, as any intentional or unintentional distortion of the raw data provides a significant contrast ratio derived from the average sample values. Application of this method to the analysis of ballistic data base of naval artillery allowed to find the facts, forcing a new look at some of the events in the history data on the German naval artillery before World War I, probably overpriced for disinformation opponents of the Entente; during the First World War, Spain, apparently held secret talks with the firm Bofors ended purchase of Swedish shells; the first Russian naval rifled guns were created obvious based on the project Blackly, not Krupp as traditionally considered.

Testiranje balističke otpornosti zaštitnih prsluka / Ballistic resistance of body armour testing

Directory of Open Access Journals (Sweden)

Đuro Jovanić

2006-04-01

Full Text Available U radu je predstavljena osnova standarda NIJ 0101.04 (Nacionalni Institut Pravde, namenjenog za utvrđivanje minimuma tehničkih zahteva i propisivanje metoda ispitivanja balističke otpornosti zaštitnih prsluka, koji treba da zaštite gornji deo tela od dejstva streljačkog oružja. Standard jeste revizija standarda NIJ 0101.03 iz aprila 1987. i preciznije definiše zahteve u pogledu obeležavanja, kriterijume za prijem i postupke merenja otiska u materijalu iza prsluka. Područje ovog standarda odnosi se samo na balističku otpornost, ali ne i na pretnje od noža i predmeta sa oštrim vrhom. Takođe, ne odnosi se na zaštitne prsluke koji sadrže dopunske elemente ili varijacije u konstrukciji balističkih panela za malu površinu torza, radi povećanja osnovnog nivoa zaštite na ograničenim površinama (bilo balističke ili povrede od tupog vrha. / This work is a basic presentation of NIJ 0101.04 (National Institute of Justice standard, -whose purpose is to establish minimum performance requirements and methods of testing ballistic resistance of body armor intended to protect the torso against gunfire. This standard is a revision of NIJ Standard 0101.03 dated April 1987 and it clarifies the labeling requirements, acceptance criteria, and backface signature measurement procedure. The scope of this standard is limited only to ballistic resistance; and it does not include threats from knives and sharply pointed instruments. In addition, the standard does not include armor that incorporates inserts, or variations in construction of the ballistic panel over small areas of the torso, used for increasing the basic level of protection of the armor (whether ballistic or blunt trauma on localized areas.

Modeling of uranium alloy response in plane impact and reverse ballistic experiments

International Nuclear Information System (INIS)

Herrmann, B.; Landau, A.; Shvarts, D.; Favorsky, V.; Zaretsky, E.

2002-01-01

The dynamic behavior of a solution heat-treated, water-quenched and aged U-0.75wt%Ti alloy was studied in planar (disk-on-disk) and reverse ballistic (disk-on-rod) impact experiments performed with a 25 mm light-gas gun. The impact velocity ranged from 100 to 500 m/sec. The impacted samples were softly recovered for further metallographic examination. The VISAR records of the sample free surface velocity, obtained in planar impact experiments, were simulated with 1-D hydrocode for calibrating the parameters of modified Steinberg-Cochran-Guinan (SCG) constitutive equation of the alloy. The same SCG equation was employed in 2-D AUTODYN simulation of the alloy response in the reverse ballistic experiments, with VISAR monitoring of the lateral sample surface velocity. Varying the parameters of the strain-dependent failure model allows relating the features of the recorded velocity profiles with the results of the examination of the damaged samples

Research on capability of detecting ballistic missile by near space infrared system

Science.gov (United States)

Lu, Li; Sheng, Wen; Jiang, Wei; Jiang, Feng

2018-01-01

The infrared detection technology of ballistic missile based on near space platform can effectively make up the shortcomings of high-cost of traditional early warning satellites and the limited earth curvature of ground-based early warning radar. In terms of target detection capability, aiming at the problem that the formula of the action distance based on contrast performance ignores the background emissivity in the calculation process and the formula is only valid for the monochromatic light, an improved formula of the detecting range based on contrast performance is proposed. The near space infrared imaging system parameters are introduced, the expression of the contrastive action distance formula based on the target detection of the near space platform is deduced. The detection range of the near space infrared system for the booster stage ballistic missile skin, the tail nozzle and the tail flame is calculated. The simulation results show that the near-space infrared system has the best effect on the detection of tail-flame radiation.

System Architecture for Anti-Ship Ballistic Missile Defense (ASBMD)

OpenAIRE

Hobgood, Jean; Madison, Kimberly; Pawlowski, Geoffrey; Nedd, Steven; Roberts, Michael; Rumberg, Paige

2009-01-01

Approved for public release; distribution is unlimited. Recent studies suggest that China is developing a new class of ballistic missiles that can be used against moving targets, such as ships. One such technology is anticipated to cover a range of 2,000 kilometers and operate at a speed of Mach 10. The threat is also capable of maneuvering both during the midcourse and terminal flight phases for the purposes of guidance, target acquisition, and countermeasures. This threat could greatl...

Simulation of two-dimensional interior ballistics model of solid propellant electrothermal-chemical launch with discharge rod plasma generator

Directory of Open Access Journals (Sweden)

Yan-jie Ni

2017-08-01

Full Text Available Instead of the capillary plasma generator (CPG, a discharge rod plasma generator (DRPG is used in the 30 mm electrothermal-chemical (ETC gun to improve the ignition uniformity of the solid propellant. An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun (2D-IB-SPETCG is presented to describe the process of the ETC launch. Both calculated pressure and projectile muzzle velocity accord well with the experimental results. The feasibility of the 2D-IB-SPETCG model is proved. Depending on the experimental data and initial parameters, detailed distribution of the ballistics parameters can be simulated. With the distribution of pressure and temperature of the gas phase and the propellant, the influence of plasma during the ignition process can be analyzed. Because of the radial flowing plasma, the propellant in the area of the DRPG is ignited within 0.01 ms, while all propellant in the chamber is ignited within 0.09 ms. The radial ignition delay time is much less than the axial delay time. During the ignition process, the radial pressure difference is less than 5  MPa at the place 0.025 m away from the breech. The radial ignition uniformity is proved. The temperature of the gas increases from several thousand K (conventional ignition to several ten thousand K (plasma ignition. Compare the distribution of the density and temperature of the gas, we know that low density and high temperature gas appears near the exits of the DRPG, while high density and low temperature gas appears at the wall near the breech. The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch. The 2D-IB-SPETC model can be used for prediction and improvement of experiments.

Atmospheric Entry Studies for Venus Missions: 45 Sphere-Cone Rigid Aeroshells and Ballistic Entries

Science.gov (United States)

Prabhu, Dinesh K.; Spilker, Thomas R.; Allen, Gary A., Jr.; Hwang, Helen H.; Cappuccio, Gelsomina; Moses, Robert W.

2013-01-01

The present study considers direct ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and heatshield diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DoF trajectory code, TRAJ. From these trajectories, the viable entry flight path angle space is determined through the use of mechanical and thermal performance limits on the thermal protection material and science payload; the thermal protection material of choice is entry-grade carbon phenolic, for which a material thermal response model is available. For mechanical performance, a 200 g limit is placed on the peak deceleration load experienced by the science instruments, and 10 bar is assumed as the pressure limit for entry-grade carbon-phenolic material. For thermal performance, inflection points in the total heat load distribution are used as cut off criteria. Analysis of the results shows the existence of a range of critical ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of the material rather than the deceleration load limit.

77 FR 6548 - Notice of Availability of Ballistic Survivability, Lethality and Vulnerability Analyses

Science.gov (United States)

2012-02-08

... DEPARTMENT OF DEFENSE Department of the Army Notice of Availability of Ballistic Survivability, Lethality and Vulnerability Analyses AGENCY: Department of the Army, DoD. ACTION: Notice of availability. SUMMARY: The US Army Research Laboratory's (ARL's), Survivability, Lethality Analysis Directorate (SLAD...

Ballistic Limit of High-Strength Steel and Al7075-T6 Multi-Layered Plates Under 7.62-mm Armour Piercing Projectile Impact

Directory of Open Access Journals (Sweden)

N. A. Rahman

Full Text Available Abstract This paper presents the computational-based ballistic limit of laminated metal panels comprised of high strength steel and aluminium alloy Al7075-T6 plate at different thickness combinations to necessitate the weight reduction of existing armour steel plate. The numerical models of monolithic configuration, double-layered configuration and triple-layered configuration were developed using a commercial explicit finite element code and were impacted by 7.62 mm armour piercing projectile at velocity range of 900 to 950 m/s. The ballistic performance of each configuration plate in terms of ballistic limit velocity, penetration process and permanent deformation was quantified and considered. It was found that the monolithic panel of high-strength steel has the best ballistic performance among all panels, yet it has not caused any weight reduction in existing armour plate. As the weight reduction was increased from 20-30%, the double-layered configuration panels became less resistance to ballistic impact where only at 20% and 23.2% of weight reduction panel could stop the 950m/s projectile. The triple-layered configuration panels with similar areal density performed much better where all panels subjected to 20-30% weight reductions successfully stopped the 950 m/s projectile. Thus, triple-layered configurations are interesting option in designing a protective structure without sacrificing the performance in achieving weight reduction.

Ballistic transport of spin waves incident from cobalt leads across cobalt–gadolinium alloy nanojunctions

International Nuclear Information System (INIS)

Ashokan, V.; Abou Ghantous, M.; Ghader, D.; Khater, A.

2014-01-01

Calculations are presented for the scattering and ballistic transport of spin waves (SW) incident from cobalt leads, on ultrathin ferrimagnetic cobalt–gadolinium ‥Co][Co (1−c) Gd (c) ] ℓ [Co‥ nanojunction systems. The nanojunction [Co (1−c) Gd (c) ] ℓ itself is a randomly disordered alloy of thickness ℓ hcp lattice planes between matching hcp planes of the Co leads, at known stable concentrations c≤0.5 for this alloy system. To compute the spin dynamics, and the SW scattering and ballistic transport, this alloy nanojunction is modeled in the virtual crystal approximation (VCA), valid in particular at the length scale of the nanojunction for submicroscopic SW wavelengths. The phase field matching theory (PFMT) is applied to compute the localized and resonant magnons on the nanojunction. These magnons, characteristic of the embedded nanostructure, propagate in its symmetry plane with spin precession amplitudes that decay or match the spin wave states in the semi-infinite leads. The eigenvectors of these magnon modes are calculated for certain cases to illustrate the spin precession configurations on the nanojunction. The VCA-PFMT approach is also used to calculate the reflection and transmission spectra for the spin waves incident from the Co leads on the nanojunction. The results demonstrate resonance assisted maxima for the ballistic SW transmission spectra due to interactions between the incident spin waves and the nanojunction magnon modes. These properties are general for variable nanojunction thicknesses and alloy stable concentrations c≤0.5. In particular, the positions of the resonance assisted maxima of spin wave transmission can be modified with nanojunction thickness and alloy concentration. - Highlights: • Model is presented for spin wave scattering at CoGd disordered alloy nanojunctions. • Computations yield the localized and resonant magnon modes on the nanojunctions. • The spin waves ballistic reflection and transmission

Ballistic and snake photon imaging for locating optical endomicroscopy fibres

Science.gov (United States)

Tanner, M. G.; Choudhary, T. R.; Craven, T. H.; Mills, B.; Bradley, M.; Henderson, R. K.; Dhaliwal, K.; Thomson, R. R.

2017-01-01

We demonstrate determination of the location of the distal-end of a fibre-optic device deep in tissue through the imaging of ballistic and snake photons using a time resolved single-photon detector array. The fibre was imaged with centimetre resolution, within clinically relevant settings and models. This technique can overcome the limitations imposed by tissue scattering in optically determining the in vivo location of fibre-optic medical instruments. PMID:28966848

An Investigation of the Academic Information Finding and Re-finding Behavior on the Web

Directory of Open Access Journals (Sweden)

Hsiao-Tieh Pu

2014-12-01

Full Text Available Academic researchers often need and re-use relevant information found after a period of time. This preliminary study used various methods, including experiments, interviews, search log analysis, sequential analysis, and observation to investigate characteristics of academic information finding and re-finding behavior. Overall, the participants in this study entered short queries either in finding or re-finding phases. Comparatively speaking, the participants entered greater number of queries, modified more queries, browsed more web pages, and stayed longer on web pages in the finding phase. On the other hand, in the re-finding phase, they utilized personal information management tools to re-find instead of finding again using search engine, such as checking browsing history; moreover, they tend to input less number of queries and stayed shorter on web pages. In short, the participants interacted more with the retrieval system during the finding phase, while they increased the use of personal information management tools in the re-finding phase. As to the contextual clues used in re-finding phase, the participants used less clues from the target itself, instead, they used indirect clues more often, especially location-related information. Based on the results of sequential analysis, the transition states in the re-finding phase was found to be more complex than those in the finding phase. Web information finding and re-finding behavior is an important and novel area of research. The preliminary results would benefit research on Web information re-finding behavior, and provide useful suggestions for developing personal academic information management systems. [Article content in Chinese

Attenuation of blast pressure behind ballistic protective vests.

Science.gov (United States)

Wood, Garrett W; Panzer, Matthew B; Shridharani, Jay K; Matthews, Kyle A; Capehart, Bruce P; Myers, Barry S; Bass, Cameron R

2013-02-01

Clinical studies increasingly report brain injury and not pulmonary injury following blast exposures, despite the increased frequency of exposure to explosive devices. The goal of this study was to determine the effect of personal body armour use on the potential for primary blast injury and to determine the risk of brain and pulmonary injury following a blast and its impact on the clinical care of patients with a history of blast exposure. A shock tube was used to generate blast overpressures on soft ballistic protective vests (NIJ Level-2) and hard protective vests (NIJ Level-4) while overpressure was recorded behind the vest. Both types of vest were found to significantly decrease pulmonary injury risk following a blast for a wide range of conditions. At the highest tested blast overpressure, the soft vest decreased the behind armour overpressure by a factor of 14.2, and the hard vest decreased behind armour overpressure by a factor of 56.8. Addition of body armour increased the 50th percentile pulmonary death tolerance of both vests to higher levels than the 50th percentile for brain injury. These results suggest that ballistic protective body armour vests, especially hard body armour plates, provide substantial chest protection in primary blasts and explain the increased frequency of head injuries, without the presence of pulmonary injuries, in protected subjects reporting a history of blast exposure. These results suggest increased clinical suspicion for mild to severe brain injury is warranted in persons wearing body armour exposed to a blast with or without pulmonary injury.

Ballistic thermoelectric transport in a Luttinger liquid

International Nuclear Information System (INIS)

Ivanov, Y V

2010-01-01

The Seebeck and Peltier coefficients of a homogeneous Luttinger liquid are calculated in the ballistic regime. Nonlinearity of the electron spectrum is taken into account. It is shown that, in the framework of the defined approximations, the thermoelectric power of a Luttinger liquid is equal to zero, in agreement with the exponentially small thermopower of a one-dimensional degenerate Fermi gas. The Peltier coefficient is controlled by a nonequilibrium state of the system. It is finite and renormalized by the interaction in the case of a convective flow of a Luttinger liquid. The zero modes of bosonic excitations and the dispersion-induced contribution to the electric current operator are taken into account in calculations.

Ballistic Missile Defense: New Plans, Old Challenges

Directory of Open Access Journals (Sweden)

Elizabeth Zolotukhina

2010-01-01

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

Ballistic strength training compared with usual care for improving mobility following traumatic brain injury: protocol for a randomised, controlled trial

Directory of Open Access Journals (Sweden)

Gavin Williams

2016-07-01

Discussion: Strength training in neurological rehabilitation is highly topical because muscle weakness has been identified as the primary impairment leading to mobility limitations in many neurological populations. This project represents the first international study of ballistic strength training after traumatic brain injury. The novelty of ballistic strength training is that the exercises attempt to replicate how lower limb muscles work, by targeting the high angular velocities attained during walking and higher level activities.

Analysis and optimization of trajectories for Ballistic Missiles Interception

OpenAIRE

Montero Yéboles, Daniel

2016-01-01

Intercontinental Ballistic Missiles are capable of placing a nuclear warhead at more than 5,000 km away from its launching base. With the lethal power of a nuclear warhead a whole city could be wiped out by a single weapon causing millions of deaths. This means that the threat posed to any country from a single ICBM captured by a terrorist group or launched by a 'rogue' state is huge. This threat is increasing as more countries are achieving nuclear and advanced launcher capabilities. In orde...

Aero-Assisted Pre-Stage for Ballistic and Aero-Assisted Launch Vehicles

Science.gov (United States)

Ustinov, Eugene A.

2012-01-01

A concept of an aero-assisted pre-stage is proposed, which enables launch of both ballistic and aero-assisted launch vehicles from conventional runways. The pre-stage can be implemented as a delta-wing with a suitable undercarriage, which is mated with the launch vehicle, so that their flight directions are coaligned. The ample wing area of the pre-stage combined with the thrust of the launch vehicle ensure prompt roll-out and take-off of the stack at airspeeds typical for a conventional jet airliner. The launch vehicle is separated from the pre-stage as soon as safe altitude is achieved, and the desired ascent trajectory is reached. Nominally, the pre-stage is non-powered. As an option, to save the propellant of the launch vehicle, the pre-stage may have its own short-burn propulsion system, whereas the propulsion system of the launch vehicle is activated at the separation point. A general non-dimensional analysis of performance of the pre-stage from roll-out to separation is carried out and applications to existing ballistic launch vehicle and hypothetical aero-assisted vehicles (spaceplanes) are considered.

Cooperative Monitoring Center Occasional Paper/9: De-Alerting Strategic Ballistic Missiles

Energy Technology Data Exchange (ETDEWEB)

Connell, Leonard W.; Edenburn, Michael W.; Fraley, Stanley K.; Trost, Lawrence C.

1999-03-01

This paper presents a framework for evaluating the technical merits of strategic ballistic missile de-alerting measures, and it uses the framework to evaluate a variety of possible measures for silo-based, land-mobile, and submarine-based missiles. De-alerting measures are defined for the purpose of this paper as reversible actions taken to increase the time or effort required to launch a strategic ballistic missile. The paper does not assess the desirability of pursuing a de-alerting program. Such an assessment is highly context dependent. The paper postulates that if de-alerting is desirable and is used as an arms control mechanism, de-alerting measures should satisfy specific cirteria relating to force security, practicality, effectiveness, significant delay, and verifiability. Silo-launched missiles lend themselves most readily to de-alerting verification, because communications necessary for monitoring do not increase the vulnerabilty of the weapons by a significant amount. Land-mobile missile de-alerting measures would be more challenging to verify, because monitoring measures that disclose the launcher's location would potentially increase their vulnerability. Submarine-launched missile de-alerting measures would be extremely challlenging if not impossible to monitor without increasing the submarine's vulnerability.

Challenges in the Acceptance/Licensing of a Mobile Ballistic Missile Range Safety Technology (BMRST) System

National Research Council Canada - National Science Library

Bartone, Chris

2001-01-01

...), Space Vehicle Directorate, Ballistic Missile Technology program. The BMRST Program is to develop and to demonstrate a "certifiable" mobile launch range tracking and control system based upon the Global Positioning System (GPS...

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

Science.gov (United States)

Brock, Joseph M; Stern, Eric

2016-01-01

Dynamic CFD simulations of the SIAD ballistic test model were performed using US3D flow solver. Motivation for performing these simulations is for the purpose of validation and verification of the US3D flow solver as a viable computational tool for predicting dynamic coefficients.

48 CFR 225.7016 - Restriction on Ballistic Missile Defense research, development, test, and evaluation.

Science.gov (United States)

2010-10-01

... Missile Defense research, development, test, and evaluation. 225.7016 Section 225.7016 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE SOCIOECONOMIC PROGRAMS... Acquisition 225.7016 Restriction on Ballistic Missile Defense research, development, test, and evaluation. [68...

Force-Velocity Relationship of Upper Body Muscles: Traditional Versus Ballistic Bench Press.

Science.gov (United States)

García-Ramos, Amador; Jaric, Slobodan; Padial, Paulino; Feriche, Belén

2016-04-01

This study aimed to (1) evaluate the linearity of the force-velocity relationship, as well as the reliability of maximum force (F0), maximum velocity (V0), slope (a), and maximum power (P0); (2) compare these parameters between the traditional and ballistic bench press (BP); and (3) determine the correlation of F0 with the directly measured BP 1-repetition maximum (1RM). Thirty-two men randomly performed 2 sessions of traditional BP and 2 sessions of ballistic BP during 2 consecutive weeks. Both the maximum and mean values of force and velocity were recorded when loaded by 20-70% of 1RM. All force-velocity relationships were strongly linear (r > .99). While F0 and P0 were highly reliable (ICC: 0.91-0.96, CV: 3.8-5.1%), lower reliability was observed for V0 and a (ICC: 0.49-0.81, CV: 6.6-11.8%). Trivial differences between exercises were found for F0 (ES: velocity relationship is useful to assess the upper body maximal capabilities to generate force, velocity, and power.

Effective thermal conductivity of superfluid helium: laminar, turbulent and ballistic regimes

Directory of Open Access Journals (Sweden)

Sciacca Michele

2016-06-01

Full Text Available In this paper we extend previous results on the effective thermal conductivity of liquid helium II in cylindrical channels to rectangular channels with high aspect ratio. The aim is to compare the results in the laminar regime, the turbulent regime and the ballistic regime, all of them obtained within a single mesoscopic formalism of heat transport, with heat flux as an independent variable.

Multiple-Sensor Discrimination of Closely-Spaced Objects on a Ballistic Trajectory

Science.gov (United States)

2015-05-18

Modeling Two-body orbit dynamics was utilized to generate ballistic trajectories between the desired burnout and reentry points. The dispersion of object...trajectories within the target complex was achieved by varying the velocity of each object at the burnout points. The generated trajectories served...utilized as it removes several limitations associated with using the Euclidean distance mainly that it accounts for the scaling of the coordinate

Mechanical properties of silicone based composites as a temperature insensitive ballistic backing material for quantifying back face deformation.

Science.gov (United States)

Edwards, Tara D; Bain, Erich D; Cole, Shawn T; Freeney, Reygan M; Halls, Virginia A; Ivancik, Juliana; Lenhart, Joseph L; Napadensky, Eugene; Yu, Jian H; Zheng, James Q; Mrozek, Randy A

2018-04-01

This paper describes a new witness material for quantifying the back face deformation (BFD) resulting from high rate impact of ballistic protective equipment. Accurate BFD quantification is critical for the assessment and certification of personal protective equipment, such as body armor and helmets, and ballistic evaluation. A common witness material is ballistic clay, specifically, Roma Plastilina No. 1 (RP1). RP1 must be heated to nearly 38°C to pass calibration, and used within a limited time frame to remain in calibration. RP1 also exhibits lot-to-lot variability and is sensitive to time, temperature, and handling procedures, which limits the BFD accuracy and reproducibility. A new silicone composite backing material (SCBM) was developed and tested side-by-side with heated RP1 using quasi-static indentation and compression, low velocity impact, spherical projectile penetration, and both soft and hard armor ballistic BFD measurements to compare their response over a broad range of strain rates and temperatures. The results demonstrate that SCBM mimics the heated RP1 response at room temperature and exhibits minimal temperature sensitivity. With additional optimization of the composition and processing, SCBM could be a drop-in replacement for RP1 that is used at room temperature during BFD quantification with minimal changes to the current RP1 handling protocols and infrastructure. It is anticipated that removing the heating requirement, and temperature-dependence, associated with RP1 will reduce test variability, simplify testing logistics, and enhance test range productivity. Published by Elsevier B.V.

Ballistic energy transport in PEG oligomers

Directory of Open Access Journals (Sweden)

Kireev Victor V.

2013-03-01

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

A Survey of Ballistic Transfers to Low Lunar Orbit

Science.gov (United States)

Parker, Jeffrey S.; Anderson, Rodney L.; Peterson, Andrew

2011-01-01

A simple strategy is identified to generate ballistic transfers between the Earth and Moon, i.e., transfers that perform two maneuvers: a trans-lunar injection maneuver to depart the Earth and a Lunar Orbit Insertion maneuver to insert into orbit at the Moon. This strategy is used to survey the performance of numerous transfers between varying Earth parking orbits and varying low lunar target orbits. The transfers surveyed include short 3-6 day direct transfers, longer 3-4 month low energy transfers, and variants that include Earth phasing orbits and/or lunar flybys.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

Energy Technology Data Exchange (ETDEWEB)

Zheng, Yipeng; Tan, Wenjiang, E-mail: tanwenjiang@mail.xjtu.edu.cn; Si, Jinhai; Ren, YuHu; Xu, Shichao; Hou, Xun [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xianning-xilu 28, Xi' an 710049 (China); Tong, Junyi [Departments of Applied Physics, Xi' an University of Technology, Xi' an 710048 (China)

2016-09-07

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. This imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.

Anti-Ballistic Missile Laser Predictive Avoidance of Satellites: Theory and Software for Real-Time Processing and Deconfliction of Satellite Ephemerides With a Moving Platform Laser, Book 1

National Research Council Canada - National Science Library

vloedman, David

1999-01-01

The Anti-Ballistic missile Laser (ABL) Project is committed to defense against attack from enemy-launched Theater Ballistic Missiles using an airborne laser platform to disable an enemy missile in the boost phase of launch...

Observation of strong reflection of electron waves exiting a ballistic channel at low energy

Energy Technology Data Exchange (ETDEWEB)

Vaz, Canute I.; Campbell, Jason P.; Ryan, Jason T.; Gundlach, David; Cheung, Kin. P., E-mail: Kin.Cheung@NIST.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Liu, Changze [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Institute of Microelectronics, Peking University, Beijing 100871 (China); Southwick, Richard G. [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); IBM Research, Albany, NY 12205 (United States); Oates, Anthony S. [Taiwan Semiconductor Manufacturing Corporation, Hsinchu 30844, Taiwan (China); Huang, Ru [Institute of Microelectronics, Peking University, Beijing 100871 (China)

2016-06-15

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

Multi response optimization of wire-EDM process parameters of ballistic grade aluminium alloy

Directory of Open Access Journals (Sweden)

Ravindranadh Bobbili

2015-12-01

Full Text Available In the current investigation, a multi response optimization technique based on Taguchi method coupled with Grey relational analysis is planned for wire-EDM operations on ballistic grade aluminium alloy for armour applications. Experiments have been performed with four machining variables: pulse-on time, pulse-off time, peak current and spark voltage. Experimentation has been planned as per Taguchi technique. Three performance characteristics namely material removal rate (MRR, surface roughness (SR and gap current (GC have been chosen for this study. Results showed that pulse-on time, peak current and spark voltage were significant variables to Grey relational grade. Variation of performance measures with process variables was modelled by using response surface method. The confirmation tests have also been performed to validate the results obtained by Grey relational analysis and found that great improvement with 6% error is achieved.

Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch

Science.gov (United States)

Metzger, Philip T.; Lane, John E.; Carilli, Robert A.; Long, Jason M.; Shawn, Kathy L.

2010-07-01

A method combining photogrammetry with ballistic analysis is demonstrated to identify flying debris in a rocket launch environment. Debris traveling near the STS-124 Space Shuttle was captured on cameras viewing the launch pad within the first few seconds after launch. One particular piece of debris caught the attention of investigators studying the release of flame trench fire bricks because its high trajectory could indicate a flight risk to the Space Shuttle. Digitized images from two pad perimeter high-speed 16-mm film cameras were processed using photogrammetry software based on a multi-parameter optimization technique. Reference points in the image were found from 3D CAD models of the launch pad and from surveyed points on the pad. The three-dimensional reference points were matched to the equivalent two-dimensional camera projections by optimizing the camera model parameters using a gradient search optimization technique. Using this method of solving the triangulation problem, the xyz position of the object's path relative to the reference point coordinate system was found for every set of synchronized images. This trajectory was then compared to a predicted trajectory while performing regression analysis on the ballistic coefficient and other parameters. This identified, with a high degree of confidence, the object's material density and thus its probable origin within the launch pad environment. Future extensions of this methodology may make it possible to diagnose the underlying causes of debris-releasing events in near-real time, thus improving flight safety.

A Comparison of the Deformation Flow and Failure of Two Tungsten Heavy Alloys in Ballistic Impacts

National Research Council Canada - National Science Library

Schuster, Brian E; Peterson, Bryan P; Magness, Lee S

2006-01-01

.... Small, but consistent, differences in the ballistic performances of the two lots of penetrators were observed in depth of penetration tests, in thick armor steel targets, and in limit velocity...

Quantum Interference Control of Ballistic Magneto- resistance in a Magnetic Nanowire Containing Two Atomic- Size Domain Walls

Directory of Open Access Journals (Sweden)

V. Fallahi

2012-06-01

Full Text Available The magnetoresistance of a one-dimensional electron gas in a metallic ferromagnetic nanowire containing two atomic-size domain walls has been investigated in the presence of spin-orbit interaction. The magnetoresistance is calculated in the ballistic regime, within the Landauer-Büttiker formalism. It has been demonstrated that the conductance of a magnetic nanowire with double domain walls can be controlled through the domain walls separation. Also, we have represented another alternative way that enables us to handle easily the magnetoresistance of such a system as well as its conductance by utilizing the Rashba-type spin-orbit interaction induced by the external gates.

A biologically inspired neural network controller for ballistic arm movements

Directory of Open Access Journals (Sweden)

Schmid Maurizio

2007-09-01

Full Text Available Abstract Background In humans, the implementation of multijoint tasks of the arm implies a highly complex integration of sensory information, sensorimotor transformations and motor planning. Computational models can be profitably used to better understand the mechanisms sub-serving motor control, thus providing useful perspectives and investigating different control hypotheses. To this purpose, the use of Artificial Neural Networks has been proposed to represent and interpret the movement of upper limb. In this paper, a neural network approach to the modelling of the motor control of a human arm during planar ballistic movements is presented. Methods The developed system is composed of three main computational blocks: 1 a parallel distributed learning scheme that aims at simulating the internal inverse model in the trajectory formation process; 2 a pulse generator, which is responsible for the creation of muscular synergies; and 3 a limb model based on two joints (two degrees of freedom and six muscle-like actuators, that can accommodate for the biomechanical parameters of the arm. The learning paradigm of the neural controller is based on a pure exploration of the working space with no feedback signal. Kinematics provided by the system have been compared with those obtained in literature from experimental data of humans. Results The model reproduces kinematics of arm movements, with bell-shaped wrist velocity profiles and approximately straight trajectories, and gives rise to the generation of synergies for the execution of movements. The model allows achieving amplitude and direction errors of respectively 0.52 cm and 0.2 radians. Curvature values are similar to those encountered in experimental measures with humans. The neural controller also manages environmental modifications such as the insertion of different force fields acting on the end-effector. Conclusion The proposed system has been shown to properly simulate the development of

Supercurrent through a spin-split quasi-ballistic point contact in an InAs nanowire

DEFF Research Database (Denmark)

Saldaña, J. C. Estrada; Žitko, R.; Cleuziou, J. P.

2018-01-01

We study the superconducting proximity effect in an InAs nanowire contacted by Ta-based superconducting electrodes. Using local bottom gates, we control the potential landscape along the nanowire, tuning its conductance to a quasi-ballistic regime. At high magnetic field ($B$), we observe...

Live RB51 vaccine lyophilized hydrogel formulations with increased shelf life for practical ballistic delivery

Science.gov (United States)

Ballistic delivery capability is essential to delivering vaccines and other therapeutics effectively to both livestock and wildlife in many global scenarios. Here, lyophilized poly(ethylene glycol) (PEG)-glycolide dimethacrylate crosslinked but degradable hydrogels were assessed as payload vehicles ...

Low velocity gunshot wounds result in significant contamination regardless of ballistic characteristics.

Science.gov (United States)

Weinstein, Joseph; Putney, Emily; Egol, Kenneth

2014-01-01

Controversy exists among the orthopedic community regarding the treatment of gunshot injuries. No consistent treatment algorithm exists for treatment of low energy gunshot wound (GSW) trauma. The purpose of this study was to critically examine the wound contamination following low velocity GSW based upon bullet caliber and clothing fiber type found within the injury track. Four types of handguns were fired at ballistic gel from a 10-foot distance. Various clothing materials were applied (denim, cotton, polyester, and wool) circumferentially around the tissue agar in a loose manor. A total of 32 specimens were examined. Each caliber handgun was fired a minimum of 5 times into a gel. Regardless of bullet caliber there was gross contamination of the entire bullet track in 100% of specimens in all scenarios and for all fiber types. Furthermore, as would be expected, the degree of contamination appeared to increase as the size of the bullet increased. Low velocity GSWs result in significant contamination regardless of bullet caliber and jacket type. Based upon our results further investigation of low velocity GSW tracks is warranted. Further clinical investigation should focus on the degree to which debridement should be undertaken.

Enhancement in ballistic performance of composite hard armor through carbon nanotubes

Directory of Open Access Journals (Sweden)

Jason Gibson

2013-12-01

Full Text Available The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1 for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance.

Management of High-energy Avulsive Ballistic Facial Injury: A Review of the Literature and Algorithmic Approach.

Science.gov (United States)

Vaca, Elbert E; Bellamy, Justin L; Sinno, Sammy; Rodriguez, Eduardo D

2018-03-01

High-energy avulsive ballistic facial injuries pose one of the most significant reconstructive challenges. We conducted a systematic review of the literature to evaluate management trends and outcomes for the treatment of devastating ballistic facial trauma. Furthermore, we describe the senior author's early and definitive staged reconstructive approach to these challenging patients. A Medline search was conducted to include studies that described timing of treatment, interventions, complications, and/or aesthetic outcomes. Initial query revealed 41 articles, of which 17 articles met inclusion criteria. A single comparative study revealed that early versus delayed management resulted in a decreased incidence of soft-tissue contracture, required fewer total procedures, and resulted in shorter hospitalizations (level 3 evidence). Seven of the 9 studies (78%) that advocated delayed reconstruction were from the Middle East, whereas 5 of the 6 studies (83%) advocating immediate or early definitive reconstruction were from the United States. No study compared debridement timing directly in a head-to-head fashion, nor described flap selection based on defect characteristics. Existing literature suggests that early and aggressive intervention improves outcomes following avulsive ballistic injuries. Further comparative studies are needed; however, although evidence is limited, the senior author presents a 3-stage reconstructive algorithm advocating early and definitive reconstruction with aesthetic free tissue transfer in an attempt to optimize reconstructive outcomes of these complex injuries.

Management of High-energy Avulsive Ballistic Facial Injury: A Review of the Literature and Algorithmic Approach

Science.gov (United States)

Vaca, Elbert E.; Bellamy, Justin L.; Sinno, Sammy

2018-01-01

Background: High-energy avulsive ballistic facial injuries pose one of the most significant reconstructive challenges. We conducted a systematic review of the literature to evaluate management trends and outcomes for the treatment of devastating ballistic facial trauma. Furthermore, we describe the senior author’s early and definitive staged reconstructive approach to these challenging patients. Methods: A Medline search was conducted to include studies that described timing of treatment, interventions, complications, and/or aesthetic outcomes. Results: Initial query revealed 41 articles, of which 17 articles met inclusion criteria. A single comparative study revealed that early versus delayed management resulted in a decreased incidence of soft-tissue contracture, required fewer total procedures, and resulted in shorter hospitalizations (level 3 evidence). Seven of the 9 studies (78%) that advocated delayed reconstruction were from the Middle East, whereas 5 of the 6 studies (83%) advocating immediate or early definitive reconstruction were from the United States. No study compared debridement timing directly in a head-to-head fashion, nor described flap selection based on defect characteristics. Conclusions: Existing literature suggests that early and aggressive intervention improves outcomes following avulsive ballistic injuries. Further comparative studies are needed; however, although evidence is limited, the senior author presents a 3-stage reconstructive algorithm advocating early and definitive reconstruction with aesthetic free tissue transfer in an attempt to optimize reconstructive outcomes of these complex injuries. PMID:29707453

Investigation on Mechanical Properties of Graphene Oxide reinforced GFRP

Science.gov (United States)

Arun, G. K.; Sreenivas, Nikhil; Brahma Reddy, Kesari; Sai Krishna Reddy, K.; Shashi Kumar, M. E.; Pramod, R.

2018-02-01

Graphene and E-glass fibres individually find a very wide field of applications because of their various mechanical and chemical properties. Recently graphene has attracted both academic and industrial interest because it can produce a dramatic improvement in properties at very low filler content. The primary interest of this venture is to investigate on Graphene reinforced polymer matrix nanocomposites and finding the mechanical properties. The composites were fabricated by Hand Lay Process and have been evaluated by the addition of Graphene with 1, 1.5, 2, 2.5 and 3 by weight% as reinforcement in composites. The theoretical and experimental results validate the increase in properties such as tensile strength, hardness and flexural strength with increase in weight proportions from 1% to 3% of graphene powder. It was observed that the composite material with 2.5% weight fraction of graphene yielded superior properties over other weight percentages. Graphene reinforced polymer matrix nanocomposites finds its major applications in the manufacture of aircraft bodies, ballistic missiles, sporting equipment, marine applications and extraterrestrial ventures.

Wind-driven angular momentum loss in binary systems. I - Ballistic case

Science.gov (United States)

Brookshaw, Leigh; Tavani, Marco

1993-01-01

We study numerically the average loss of specific angular momentum from binary systems due to mass outflow from one of the two stars for a variety of initial injection geometries and wind velocities. We present results of ballistic calculations in three dimensions for initial mass ratios q of the mass-losing star to primary star in the range q between 10 exp -5 and 10. We consider injection surfaces close to the Roche lobe equipotential surface of the mass-losing star, and also cases with the mass-losing star underfilling its Roche lobe. We obtain that the orbital period is expected to have a negative time derivative for wind-driven secular evolution of binaries with q greater than about 3 and with the mass-losing star near filling its Roche lobe. We also study the effect of the presence of an absorbing surface approximating an accretion disk on the average final value of the specific angular momentum loss. We find that the effect of an accretion disk is to increase the wind-driven angular momentum loss. Our results are relevant for evolutionary models of high-mass binaries and low-mass X-ray binaries.

Modelling of Ballistic Impact over a Ceramic-Metal Protection System

Directory of Open Access Journals (Sweden)

Leandro Neckel

2013-01-01

Full Text Available The behavior of ceramic-metal protection against a projectile impact is modeled. The model takes into account the mass and velocity for each stage of the phenomenon. A former model was modified considering more realistic parameters such as geometries and deformation profile. To analyze the model, simulations on different parameters have been run. The impact results of different ballistic projectiles were simulated, and the movement was plotted. In addition, a deterministic simulation on the mechanical properties of the back metal plate properties was done.

Heterogeneous propellant internal ballistics: criticism and regeneration

Science.gov (United States)

Glick, R. L.

2011-10-01

Although heterogeneous propellant and its innately nondeterministic, chemically discrete morphology dominates applications, ballisticcharacterization deterministic time-mean burning rate and acoustic admittance measures' absence of explicit, nondeterministic information requires homogeneous propellant with a smooth, uniformly regressing burning surface: inadequate boundary conditions for heterogeneous propellant grained applications. The past age overcame this dichotomy with one-dimensional (1D) models and empirical knowledge from numerous, adequately supported motor developments and supplementary experiments. However, current cost and risk constraints inhibit this approach. Moreover, its fundamental science approach is more sensitive to incomplete boundary condition information (garbage-in still equals garbage-out) and more is expected. This work critiques this situation and sketches a path forward based on enhanced ballistic and motor characterizations in the workplace and approximate model and apparatus developments mentored by CSAR DNS capabilities (or equivalent).

Glucose and oxygen metabolism after penetrating ballistic-like brain injury

Science.gov (United States)

Gajavelli, Shyam; Kentaro, Shimoda; Diaz, Julio; Yokobori, Shoji; Spurlock, Markus; Diaz, Daniel; Jackson, Clayton; Wick, Alexandra; Zhao, Weizhao; Leung, Lai Y; Shear, Deborah; Tortella, Frank; Bullock, M Ross

2015-01-01

Traumatic brain injury (TBI) is a major cause of death and disability in all age groups. Among TBI, penetrating traumatic brain injuries (PTBI) have the worst prognosis and represent the leading cause of TBI-related morbidity and death. However, there are no specific drugs/interventions due to unclear pathophysiology. To gain insights we looked at cerebral metabolism in a PTBI rat model: penetrating ballistic-like brain injury (PBBI). Early after injury, regional cerebral oxygen tension and consumption significantly decreased in the ipsilateral cortex in the PBBI group compared with the control group. At the same time point, glucose uptake was significantly reduced globally in the PBBI group compared with the control group. Examination of Fluorojade B-stained brain sections at 24 hours after PBBI revealed an incomplete overlap of metabolic impairment and neurodegeneration. As expected, the injury core had the most severe metabolic impairment and highest neurodegeneration. However, in the peri-lesional area, despite similar metabolic impairment, there was lesser neurodegeneration. Given our findings, the data suggest the presence of two distinct zones of primary injury, of which only one recovers. We anticipate the peri-lesional area encompassing the PBBI ischemic penumbra, could be salvaged by acute therapies. PMID:25669903

A Venus/Saturn Mission Study: 45deg Sphere-Cone Rigid Aeroshells and Ballistic Entries

Science.gov (United States)

Prabhu, Dinesh K.; Allen, Gary A.; Cappuccio, Gelsomina

2012-01-01

The present study considers ballistic entries into the atmospheres of Saturn and Venus using a 45deg sphere-cone rigid aeroshell (a legacy shape that has been successfully used in the Pioneer Venus and Galileo missions). For a number of entry mass and diameter combinations (i.e., various entries ballistic coefficients), entry velocities, and heading angles, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DOF trajectory code, TRAJ. Assuming that the thermal protection material of choice is carbon phenolic of flight heritage, the entry flight path angle space is constrained a posteriori by the mechanical and thermal performance parameters of the material. For mechanical performance, a 200 g limit is place on the peak deceleration load and 10 bar is assumed as the spallation pressure threshold for the legacy material. It is shown that both constraints cannot be active simultaneously. For thermal performance, a minimum margined heat flux threshold of 2.5 kW/sq cm is assumed for the heritage material. Using these constraints, viable entry flight path angle corridors are determined. Analysis of the results also hints at the existence of a "critical" ballistic coefficient beyond which the steepest possible entries are determined by the spallation pressure threshold. The results are verified against known performance of the various probes used in the Galileo and Pioneer Venus missions. It is hoped that the results presented here will serve as a baseline in the development of a new class of ablative materials for Venus and Saturn missions being considered in a future New Frontiers class of NASA missions.

Ballistic stretching increases flexibility and acute vertical jump height when combined with basketball activity.

Science.gov (United States)

Woolstenhulme, Mandy T; Griffiths, Christine M; Woolstenhulme, Emily M; Parcell, Allen C

2006-11-01

Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week -1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p basketball play, as it is beneficial to vertical jump performance.

Manganese oxalate nanorods as ballistic modifier for composite solid propellants

Energy Technology Data Exchange (ETDEWEB)

Singh, Supriya [Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, U.P. (India); Chawla, Mohit [School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, H.P. (India); Siril, Prem Felix, E-mail: prem@iitmandi.ac.in [School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, H.P. (India); Singh, Gurdip [Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, U.P. (India)

2014-12-10

Highlights: • Manganese oxalate nanorods were prepared using mild thermal precipitation and aging. • The nanorods were found to be efficient ballistic modifier for solid propellants. • The nanorods sensitized the thermolysis of ammonium perchlorate. • Controlled thermal decomposition of nanorods yielded manganese oxide nanoparticles. • MnO nanoparticles formed insitu in the condensed phase enhance the burning rates. - Abstract: Rod-shaped nanostructures of manganese oxalate (MnC{sub 2}O{sub 4}) were synthesized via mild thermal precipitation and aging process. Chemical composition of the MnC{sub 2}O{sub 4} nanorods was confirmed using Fourier transform infra-red (FTIR) spectroscopy and energy dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies revealed the crystal structure. Field emission scanning electron microscopy (FE-SEM) imaging and high resolution transmission electron microscopy (HR-TEM) were employed to study the structural features of the nanorods. The MnC{sub 2}O{sub 4} nanorods were found to be efficient ballistic modifier for the burning rate enhancement of composite solid propellants (CSPs). Thermal analysis using TGA-DSC showed that MnC{sub 2}O{sub 4} nanorods sensitized the thermal decomposition of ammonium perchlorate (AP) and the CSPs. Controlled thermal decomposition of the MnC{sub 2}O{sub 4} nanorods resulted in the formation of managanese oxide nanoparticles with mesoporosity. A plausible mechanism for the burning rate enhancement using MnC{sub 2}O{sub 4} nanorods was proposed.

Ballistic impacts on an anatomically correct synthetic skull with a surrogate skin/soft tissue layer.

Science.gov (United States)

Mahoney, Peter; Carr, Debra; Arm, Richard; Gibb, Iain; Hunt, Nicholas; Delaney, Russ J

2018-03-01

The aim of this work was to further develop a synthetic model of ballistic head injury by the addition of skin and soft tissue layers to an anatomically correct polyurethane skull filled with gelatine 10% by mass. Six head models were impacted with 7.62 x 39 mm full metal jacket mild steel core (FMJ MSC) bullets with a mean velocity of 652 m/s. The impact events were filmed with high-speed cameras. The models were imaged pre- and post-impact using computed tomography. The models were assessed post impact by two experienced Home Office pathologists and the images assessed by an experienced military radiologist. The findings were scored against real injuries. The entry wounds, exit wounds and fracture patterns were scored positively, but the synthetic skin and soft tissue layer was felt to be too extendable. Further work is ongoing to address this.

Ballistic Evaporation and Solvation of Helium Atoms at the Surfaces of Protic and Hydrocarbon Liquids.

Science.gov (United States)

Johnson, Alexis M; Lancaster, Diane K; Faust, Jennifer A; Hahn, Christine; Reznickova, Anna; Nathanson, Gilbert M

2014-11-06

Atomic and molecular solutes evaporate and dissolve by traversing an atomically thin boundary separating liquid and gas. Most solutes spend only short times in this interfacial region, making them difficult to observe. Experiments that monitor the velocities of evaporating species, however, can capture their final interactions with surface solvent molecules. We find that polarizable gases such as N2 and Ar evaporate from protic and hydrocarbon liquids with Maxwell-Boltzmann speed distributions. Surprisingly, the weakly interacting helium atom emerges from these liquids at high kinetic energies, exceeding the expected energy of evaporation from salty water by 70%. This super-Maxwellian evaporation implies in reverse that He atoms preferentially dissolve when they strike the surface at high energies, as if ballistically penetrating into the solvent. The evaporation energies increase with solvent surface tension, suggesting that He atoms require extra kinetic energy to navigate increasingly tortuous paths between surface molecules.

Atmospheric Entry Studies for Venus Missions: 45 deg Sphere-Cone Rigid Aeroshells and Ballistic Entries

Science.gov (United States)

Prabu, Dinesh K.; Allen, Gary A., Jr.; Cappuccio, Gelsomina; Spilker, Thomas R.; Hwang, Helen H.; Moses, Robert W.

2013-01-01

The present study considers ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and capsule diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30 is explored with a 3DOF trajectory code, TRAJ. Assuming that the thermal protection material of choice is carbon phenolic of flight heritage, the entry flight path angle space is constrained a posteriori by the mechanical and thermal performance parameters of the material. For mechanical performance, a 200 g limit is placed on the peak deceleration load and 10 bar is assumed as the limit for heritage carbon-phenolic material. It is shown that both constraints cannot be active simultaneously. For thermal performance, a heat flux 2.5 kW/sq cm is utilized as a threshold below which the heritage carbon phenolic is considered mass inefficient. Using these constraints, viable entry flight path angle corridors are determined. Analysis of the results also hints at the existence of a range of "critical" ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of 10 bar. The results are verified against known performance of the various probes used in the Pioneer Venus mission. It is anticipated that the results presented here will serve as a baseline in the development of a new class of ablative materials for future Venus missions.

Hybrid Carbon-Glass Fiber/Toughened Epoxy Thick Composite Joints Subject to Drop-Weight and Ballistic Impacts

National Research Council Canada - National Science Library

Liaw, Benjamin; Delale, Feridun

2007-01-01

... No. DAAD19-02-R-0010 to conduct research on hybrid carbon-S2 glass fiber/toughened epoxy thick-section, hybrid interwoven composite joints subject to drop-weight and ballistic impacts. Dr. Basavaraju B. Raju of U.S...

Compact modeling of nanoscale triple-gate junctionless transistors covering drift-diffusion to quasi-ballistic carrier transport

Science.gov (United States)

Oproglidis, T. A.; Karatsori, T. A.; Barraud, S.; Ghibaudo, G.; Dimitriadis, C. A.

2018-04-01

In this work, we extend our analytical compact model for nanoscale junctionless triple-gate (JL TG) MOSFETs, capturing carrier transport from drift-diffusion to quasi-ballistic regime. This is based on a simple formulation of the low-field mobility extracted from experimental data using the Y-function method, taking into account the ballistic carrier motion and an increased carrier scattering in process-induced defects near the source/drain regions. The case of a Schottky junction in non-ideal ohmic contact at the drain side was also taken into account by modifying the threshold voltage and ideality factor of the JL transistor. The model is validated with experimental data for n-channel JL TG MOSFETs with channel length varying from 95 down to 25 nm. It can be easily implemented as a compact model for use in Spice circuit simulators.

The lace expansion approach to ballistic behaviour for one-dimensional weakly self-avoiding walks

NARCIS (Netherlands)

Hofstad, van der R.W.

2001-01-01

We prove ballistic behaviour in dimension one fora model of weakly self-avoiding walks where loops of length m are penalized by a factor e -ß/mp with p¿ [0, 1] and ß sufficiently large. Furthermore, we prove that the fluctuations around the linear drift satisfy a centrallimit theorem. The proof uses

Ballistic and Diffusive Thermal Conductivity of Graphene

Science.gov (United States)

Saito, Riichiro; Masashi, Mizuno; Dresselhaus, Mildred S.

2018-02-01

This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. Phonon-related thermal conductivity of graphene is calculated as a function of the temperature and sample size of graphene in which the crossover of ballistic and diffusive thermal conductivity occurs at around 100 K. The diffusive thermal conductivity of graphene is evaluated by calculating the phonon mean free path for each phonon mode in which the anharmonicity of a phonon and the phonon scattering by a 13C isotope are taken into account. We show that phonon-phonon scattering of out-of-plane acoustic phonon by the anharmonic potential is essential for the largest thermal conductivity. Using the calculated results, we can design the optimum sample size, which gives the largest thermal conductivity at a given temperature for applying thermal conducting devices.

Ballistic magnetotransport and spin-orbit interaction in indium antimonide and indium arsenide quantum wells

Science.gov (United States)

Peters, John Archibald

While charge transport in a two-dimensional electron system (2DES) is fairly well understood, many open experimental and theoretical questions related to the spin of electrons remain. The standard 2DES embedded in Alx Ga1-xAs/GaAs heterostructures is most likely not the optimal candidate for such investigations, since spin effects as well as spin-orbit interactions are small perturbations compared to other effects. This has brought InSb- and InAs-based material systems into focus due to the possibility of large spin-orbit interactions. By utilizing elastic scattering off a lithographic barrier, we investigate the consequence of spin on different electron trajectories observed in InSb and InAs quantum wells. We focus on the physical properties of spin-dependent reflection in a 2DES and we present experimental results demonstrating a method to create spin-polarized beams of ballistic electrons in the presence of a lateral potential barrier. Spatial separation of electron spins using cyclotron motion in a weak magnetic is also achieved via transverse magnetic focusing. We also explore electrostatic gating effects in InSb/InAlSb heterostructures and demonstrate the effective use of polymethylglutarimide (PMGI) as a gate dielectric for InSb. The dependence on temperature and on front gate voltage of mobility and density are also examined, revealing a strong dependence of mobility on density. As regards front gate action, there is saturation in the density once it reaches a limiting value. Further, we investigate antidot lattices patterned on InSb/InAlSb and InAs/AlGaSb heterostructures. At higher magnetic fields, ballistic commensurability features are displayed while at smaller magnetic fields localization and quantized oscillatory phenomena appear, with marked differences between InSb and InAs. Interesting localization behavior is exhibited in InSb, with the strength of the localization peak decreasing exponentially with temperature between 0.4 K and 50 K. InAs on the

Modeling and experiments on ballistic impact into UHMWPE yarns using flat and saddle-nosed projectiles

NARCIS (Netherlands)

Phoenix, S.L.; Heisserer, U.; Werff, H. van der; Jagt-Deutekom , M.J. van der

2017-01-01

Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging

Ballistics considerations for small-caliber, low-density projectiles

International Nuclear Information System (INIS)

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

1993-01-01

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 ∼ 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

Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots

Science.gov (United States)

Meinert, Tobias; Tietz, Olaf; Palme, Klaus J.; Rohrbach, Alexander

2016-01-01

Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

Translation compensation and micro-Doppler extraction for precession ballistic targets with a wideband terahertz radar

Science.gov (United States)

Yang, Qi; Deng, Bin; Wang, Hongqiang; Zhang, Ye; Qin, Yuliang

2018-01-01

Imaging, classification, and recognition techniques of ballistic targets in midcourse have always been the focus of research in the radar field for military applications. However, the high velocity translation of ballistic targets will subject range profile and Doppler to translation, slope, and fold, which are especially severe in the terahertz region. Therefore, a two-step translation compensation method based on envelope alignment is presented. The rough compensation is based on the traditional envelope alignment algorithm in inverse synthetic aperture radar imaging, and the fine compensation is supported by distance fitting. Then, a wideband imaging radar system with a carrier frequency of 0.32 THz is introduced, and an experiment on a precession missile model is carried out. After translation compensation with the method proposed in this paper, the range profile and the micro-Doppler distributions unaffected by translation are obtained, providing an important foundation for the high-resolution imaging and micro-Doppler extraction of the terahertz radar.

Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots.

Science.gov (United States)

Meinert, Tobias; Tietz, Olaf; Palme, Klaus J; Rohrbach, Alexander

2016-08-24

Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection.

Feed-forward motor control of ultrafast, ballistic movements.

Science.gov (United States)

Kagaya, K; Patek, S N

2016-02-01

To circumvent the limits of muscle, ultrafast movements achieve high power through the use of springs and latches. The time scale of these movements is too short for control through typical neuromuscular mechanisms, thus ultrafast movements are either invariant or controlled prior to movement. We tested whether mantis shrimp (Stomatopoda: Neogonodactylus bredini) vary their ultrafast smashing strikes and, if so, how this control is achieved prior to movement. We collected high-speed images of strike mechanics and electromyograms of the extensor and flexor muscles that control spring compression and latch release. During spring compression, lateral extensor and flexor units were co-activated. The strike initiated several milliseconds after the flexor units ceased, suggesting that flexor activity prevents spring release and determines the timing of strike initiation. We used linear mixed models and Akaike's information criterion to serially evaluate multiple hypotheses for control mechanisms. We found that variation in spring compression and strike angular velocity were statistically explained by spike activity of the extensor muscle. The results show that mantis shrimp can generate kinematically variable strikes and that their kinematics can be changed through adjustments to motor activity prior to the movement, thus supporting an upstream, central-nervous-system-based control of ultrafast movement. Based on these and other findings, we present a shishiodoshi model that illustrates alternative models of control in biological ballistic systems. The discovery of feed-forward control in mantis shrimp sets the stage for the assessment of targets, strategic variation in kinematics and the role of learning in ultrafast animals. © 2016. Published by The Company of Biologists Ltd.

Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

Energy Technology Data Exchange (ETDEWEB)

Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

2015-11-15

For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

Conventional Prompt Global Strike and Long Range Ballistic Missiles: Background and Issues

Science.gov (United States)

2017-02-03

These include bombers, cruise missiles, ballistic missiles, and boost-glide technologies that would mate a rocket booster with a hypersonic glide...the early stages of development. They are envisioned to launch from air bases, like aircraft, but to travel at speeds that far exceed those of U.S...prototype rocket engine in 2005. 39 According to the Defense Science Board Task Force, this missile might have delivered a 2,000- pound payload over a

Reasons Behind the Change of American Ballistic Missile Defense Architecture in Europe

Directory of Open Access Journals (Sweden)

Radovan EUGEL

2010-12-01

Full Text Available The article analyses the change of the architecture of American ballistic missile system in Europe by Barrack Obama in September 2009. The author argues that this change was partially, but not solely, motivated by the effort to appease the Russian antagonism against this project. This is supported by various arguments for and against the assertion that it was an effort to appease Russia. Thus, the answer should be somewhere in the middle.

Comparative microstructures and cytotoxicity assays for ballistic aerosols composed of micrometals and nanometals: respiratory health implications

Science.gov (United States)

Machado, Brenda I; Suro, Raquel M; Garza, Kristine M; Murr, Lawrence E

2011-01-01

Aerosol particulates collected on filters from ballistic penetration and erosion events for W–Ni–Co and W–Ni–Fe kinetic energy rod projectiles penetrating steel target plates were observed to be highly cytotoxic to human epithelial A549 lung cells in culture after 48 hours of exposure. The aerosol consisted of micron-sized Fe particulates and nanoparticulate aggregates consisting of W, Ni or W, Co, and some Fe, characterized by scanning electron microscopy and transmission electron microscopy, and using energy-dispersive (X-ray) spectrometry for elemental analysis and mapping. Cytotoxic assays of manufactured micron-sized and nanosized metal particulates of W, Ni, Fe, and Co demonstrated that, consistent with many studies in the literature, only the nanoparticulate elements demonstrated measurable cytotoxicity. These results suggest the potential for very severe, short-term, human toxicity, in particular to the respiratory system on inhaling ballistic aerosols. PMID:21499416

Advanced ceramics reinforced with carbon nanotubes for ballistic application

International Nuclear Information System (INIS)

Couto, Carlos Alberto de Oliveira; Passador, Fabio Roberto

2016-01-01

Full text: The carbon nanotubes have excellent mechanical properties, the elastic modulus is around 1TPa, next to the diamond and the mechanical strength is 10 to 100 times higher than steel, moreover they are self-lubricating, which facilitates the ceramic composites compression process. The insertion of carbon nanotubes tends to improve the fracture toughness of ceramic composites, but is necessary to obtain a good dispersion in the ceramic matrix. The objective of this work is to develop a tough and tenacious ceramics for ballistic application, using structural ceramics of alumina and tetragonal zirconia and evaluate the influence of the addition of carbon nanotubes (multilayer) on the mechanical properties of the composite. The carbon nanotubes were functionalized with carboxylic groups by nitric acid oxidation reaction. To ensure a homogeneous distribution of the carbon nanotubes in the matrix of alumina/zirconia, surfactants were used: sodium dodecyl sulphate + gum arabic in the amount of 50% by mass of carbon nanotubes. Ceramic powders were prepared with pure alumina and alumina + 20% by mass of tetragonal zirconia/yttria, with and without addition of carbon nanotubes at concentrations of 0.1 and 0.5% by mass. The samples were uniaxially and isostatically pressed at 300 MPa and sintered in a conventional oven at 1500 °C for two hours and a heating rate of 5 °C/min, aimed at commercial application. The morphology of ceramic powders were characterized by SEM and XRD. The mechanical properties of the sintered samples were evaluated by flexural bending at three points, Vickers microhardness and fracture toughness by single edge-notched beam (SENB). The use of carbon nanotubes in the ceramic composite caused a decrease in hardness and an increase in fracture toughness, with great potential for ballistic applications. (author)

Advanced ceramics reinforced with carbon nanotubes for ballistic application

Energy Technology Data Exchange (ETDEWEB)

Couto, Carlos Alberto de Oliveira; Passador, Fabio Roberto, E-mail: carlos.couto.sjc@gmail.com [Universidade Federal de Sao Paulo (UNIFESP), Sao Jose dos Campos, SP (Brazil)

2016-07-01

Full text: The carbon nanotubes have excellent mechanical properties, the elastic modulus is around 1TPa, next to the diamond and the mechanical strength is 10 to 100 times higher than steel, moreover they are self-lubricating, which facilitates the ceramic composites compression process. The insertion of carbon nanotubes tends to improve the fracture toughness of ceramic composites, but is necessary to obtain a good dispersion in the ceramic matrix. The objective of this work is to develop a tough and tenacious ceramics for ballistic application, using structural ceramics of alumina and tetragonal zirconia and evaluate the influence of the addition of carbon nanotubes (multilayer) on the mechanical properties of the composite. The carbon nanotubes were functionalized with carboxylic groups by nitric acid oxidation reaction. To ensure a homogeneous distribution of the carbon nanotubes in the matrix of alumina/zirconia, surfactants were used: sodium dodecyl sulphate + gum arabic in the amount of 50% by mass of carbon nanotubes. Ceramic powders were prepared with pure alumina and alumina + 20% by mass of tetragonal zirconia/yttria, with and without addition of carbon nanotubes at concentrations of 0.1 and 0.5% by mass. The samples were uniaxially and isostatically pressed at 300 MPa and sintered in a conventional oven at 1500 °C for two hours and a heating rate of 5 °C/min, aimed at commercial application. The morphology of ceramic powders were characterized by SEM and XRD. The mechanical properties of the sintered samples were evaluated by flexural bending at three points, Vickers microhardness and fracture toughness by single edge-notched beam (SENB). The use of carbon nanotubes in the ceramic composite caused a decrease in hardness and an increase in fracture toughness, with great potential for ballistic applications. (author)

Surface strengthening using a self-protective diffusion paste and its application for ballistic protection of steel plates

International Nuclear Information System (INIS)

Lou, D.C.; Solberg, J.K.; Borvik, T.

2009-01-01

This paper deals with surface strengthening of steel plates using a self-protective diffusion paste. During the surface strengthening process, a paste containing carbon, boron or similar is applied on the steel surface. In addition to serving as a source for the various diffusion ingredients, the paste protects the steel against contact with the environment, so no packing or gas protection is necessary. Thus, the handling is in general very simple, and the surface strengthening process can be performed in a conventional air furnace. The method provides the same type of surface strengthening that is obtained by more conventional methods. In this work, the main focus will be surface strengthening by carburizing, but also boronizing and boronizing followed by carburizing have been tested out. The methods have been applied to increase the ballistic resistance of the low-strength carbon steel NVE36 (with nominal yield stress of 355 MPa) against impacts from small-arms bullets. An empirical model combining diffusion depth, heat-treatment temperature and soaking time was established on the basis of a series of experimental data. By means of this equation, the various heat-treatment parameters can be predicted when others are chosen. Ballistic perforation tests using 7.62 mm APM2 bullets showed that the low-strength carbon steel after surface strengthening obtained a ballistic limit higher than that of Hardox 400, which is a wear steel with a yield stress of about 1200 MPa.

The National Guard Ballistic Missile Defense Mission minutemen at the Orgital Plane

OpenAIRE

Trenary, Ralph Hiram

2004-01-01

Approved for public release; distribution is unlimited This thesis examines the decision to assign the Ballistic Missile Defense mission to units of the Colorado and Alaska National Guard. The history of the Nike Ajax, Nike Hercules, Sentinel and Safeguard programs are examined to identify the origins of support for this decision. First-hand sources provide evidence that the National Guard performance in the Nike air defense program is a record of parity and some superiority to equivalent ...

Direct observation of ballistic Andreev reflection

Science.gov (United States)

Klapwijk, T. M.; Ryabchun, S. A.

2014-12-01

An overview is presented of experiments on ballistic electrical transport in inhomogeneous superconducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale owing to the use of mechanical break-junctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In present-day research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with low-dimensional materials and topological insulators. Alternatively, the superconductor is combined with nano-objects, such as graphene, carbon nanotubes, or semiconducting nanowires. Each of these "inhomogeneous systems" provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

HVI Ballistic Limit Characterization of Fused Silica Thermal Panes

Science.gov (United States)

Miller, J. E.; Bohl, W. D.; Christiansen, E. L.; Davis, B. A.; Deighton, K. D.

2015-01-01

Fused silica window systems are used heavily on crewed reentry vehicles, and they are currently being used on the next generation of US crewed spacecraft, Orion. These systems improve crew situational awareness and comfort, as well as, insulating the reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on a fused silica window system proposed for the Orion spacecraft. A ballistic limit equation that describes the threshold of perforation of a fuse silica pane over a broad range of impact velocities, obliquities and projectile materials is discussed here.

Ballistic electron emission spectroscopy on Ag/Si devices

Energy Technology Data Exchange (ETDEWEB)

Bannani, A; Bobisch, C A; Matena, M; Moeller, R [Department of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg (Germany)], E-mail: amin.bannani@uni-due.de

2008-09-17

In this work we report on ballistic electron emission spectroscopy (BEES) studies on epitaxial layers of silver grown on silicon surfaces, with either a Si(111)-(7 x 7) or Si(100)-(2 x 1) surface reconstruction. The experiments were done at low temperature and in ultra-high vacuum (UHV). In addition, BEES measurements on polycrystalline Ag films grown on hydrogen-terminated H:Si(111)-(1 x 1) and H:Si(100)-(2 x 1) surfaces were performed. The Schottky barrier heights were evaluated by BEES. The results are compared to the values for the barrier height reported for macroscopic Schottky diodes. We show that the barrier heights for the epitaxial films substantially differ from the values measured on polycrystalline Ag films, suggesting a strong effect of the interface on the barrier height.

Microstructure evolution associated with adiabatic shear bands and shear band failure in ballistic plug formation in Ti-6Al-4V targets

International Nuclear Information System (INIS)

Murr, L.E.; Ramirez, A.C.; Gaytan, S.M.; Lopez, M.I.; Martinez, E.Y.; Hernandez, D.H.; Martinez, E.

2009-01-01

The microstructures and microstructure evolution associated with adiabatic shear band (ASB) formation in ballistic plugging in thick (2.5 cm) Ti-6Al-4V targets impacted by cylindrical, 4340 steel projectiles (2.0 cm in height) at impact velocities ranging from 633 m/s to 1027 m/s (just above the ballistic limit) were investigated by optical and transmission electron microscopy. ASB width increased from 10 μm to 21 μm as the velocity increased. ASB evolution was accompanied by the evolution of dark deformation bands composed of α' martensite platelets which increased in density with increasing impact velocity. The corresponding Vickers microindentation hardness also increased from HV 619 to HV 632 in contrast to the surrounding matrix microindentation hardness of HV 555. These deformation bands were not necessarily precursors to ASB formation. The ASB average Vickers microindentation hardness was essentially constant at HV 645, a 16% increase over the matrix. This constant microindentation hardness was characterized by a consistent DRX grain structure which varied from equiaxed, defect-free grains (∼2 μm diameter) to heavily dislocated, equiaxed grains. Cracks nucleating and propagating within the ABSs were observed to increase from 8% to 87% of the ASB length with increasing impact velocity.

Capabilities of Helmets for Preventing Head Injuries Induced by Ballistic Impacts

Directory of Open Access Journals (Sweden)

D.V. Balandin

2004-01-01

Full Text Available The limiting performance of ballistically loaded helmets designed to reduce head injuries is studied analytically. The projectile does not penetrate the helmet. This analysis evaluates the absolute minimum of the peak displacement of the helmet shell relative to the head, provided that criteria measuring the severity of head injuries lie within prescribed limits. Rather than optimize a specific design configuration, e.g. a viscoelastic foam liner, characteristics of a time-dependent force representing the helmet liner are calculated. The formulation reduces the limiting performance analysis to an optimal control problem.

A first-principles analysis of ballistic conductance, grain boundary scattering and vertical resistance in aluminum interconnects

Science.gov (United States)

Zhou, Tianji; Lanzillo, Nicholas A.; Bhosale, Prasad; Gall, Daniel; Quon, Roger

2018-05-01

We present an ab initio evaluation of electron scattering mechanisms in Al interconnects from a back-end-of-line (BEOL) perspective. We consider the ballistic conductance as a function of nanowire size, as well as the impact of surface oxidation on electron transport. We also consider several representative twin grain boundaries and calculate the specific resistivity and reflection coefficients for each case. Lastly, we calculate the vertical resistance across the Al/Ta(N)/Al and Cu/Ta(N)/Cu interfaces, which are representative of typical vertical interconnect structures with diffusion barriers. Despite a high ballistic conductance, the calculated specific resistivities at grain boundaries are 70-100% higher in Al than in Cu, and the vertical resistance across Ta(N) diffusion barriers are 60-100% larger for Al than for Cu. These results suggest that in addition to the well-known electromigration limitations in Al interconnects, electron scattering represents a major problem in achieving low interconnect line resistance at fine dimensions.

Current-driven plasmonic boom instability in three-dimensional gated periodic ballistic nanostructures

Science.gov (United States)

Aizin, G. R.; Mikalopas, J.; Shur, M.

2016-05-01

An alternative approach of using a distributed transmission line analogy for solving transport equations for ballistic nanostructures is applied for solving the three-dimensional problem of electron transport in gated ballistic nanostructures with periodically changing width. The structures with varying width allow for modulation of the electron drift velocity while keeping the plasma velocity constant. We predict that in such structures biased by a constant current, a periodic modulation of the electron drift velocity due to the varying width results in the instability of the plasma waves if the electron drift velocity to plasma wave velocity ratio changes from below to above unity. The physics of such instability is similar to that of the sonic boom, but, in the periodically modulated structures, this analog of the sonic boom is repeated many times leading to a larger increment of the instability. The constant plasma velocity in the sections of different width leads to resonant excitation of the unstable plasma modes with varying bias current. This effect (that we refer to as the superplasmonic boom condition) results in a strong enhancement of the instability. The predicted instability involves the oscillating dipole charge carried by the plasma waves. The plasmons can be efficiently coupled to the terahertz electromagnetic radiation due to the periodic geometry of the gated structure. Our estimates show that the analyzed instability should enable powerful tunable terahertz electronic sources.

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

Directory of Open Access Journals (Sweden)

Benjamin Doyon

2015-03-01

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

Picosecond ballistic imaging of diesel injection in high-temperature and high-pressure air

Science.gov (United States)

Duran, Sean P.; Porter, Jason M.; Parker, Terence E.

2015-04-01

The first successful demonstration of picosecond ballistic imaging using a 15-ps-pulse-duration laser in diesel sprays at temperature and pressure is reported. This technique uses an optical Kerr effect shutter constructed from a CS2 liquid cell and a 15-ps pulse at 532 nm. The optical shutter can be adjusted to produce effective imaging pulses between 7 and 16 ps. This technique is used to image the near-orifice region (first 3 mm) of diesel sprays from a high-pressure single-hole fuel injector. Ballistic imaging of dodecane and methyl oleate sprays injected into ambient air and diesel injection at preignition engine-like conditions are reported. Dodecane was injected into air heated to 600 °C and pressurized to 20 atm. The resulting images of the near-orifice region at these conditions reveal dramatic shedding of the liquid near the nozzle, an effect that has been predicted, but to our knowledge never before imaged. These shedding structures have an approximate spatial frequency of 10 mm-1 with lengths from 50 to 200 μm. Several parameters are explored including injection pressure, liquid fuel temperature, air temperature and pressure, and fuel type. Resulting trends are summarized with accompanying images.

Naval Theater Ballistic Missile Defense (TBMD): development of the information exchange requirements

OpenAIRE

Brintzinghoffer, Daniel M.

1996-01-01

As the United States moves into the next century one of the biggest threats facing her national interests is the proliferation of Theater Ballistic Missile (TBM) Systems, with their potential for carrying Weapons of Mass Destruction(WMD). In order for the United States to 'project power', the Navy must play a large role in the protection of friendly assets from TBM attacks. Thus, the Navy is continuing to develop new systems and technologies as it attempts to migrate older weapons systems to ...

Ultimately short ballistic vertical graphene Josephson junctions

Science.gov (United States)

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

Electron quantum optics in ballistic chiral conductors

Energy Technology Data Exchange (ETDEWEB)

Bocquillon, Erwann; Freulon, Vincent; Parmentier, Francois D.; Berroir, Jean-Marc; Placais, Bernard; Feve, Gwendal [Laboratoire Pierre Aigrain, Ecole Normale Superieure, CNRS (UMR 8551), Universite Pierre et Marie Curie, Universite Paris Diderot, Paris (France); Wahl, Claire; Rech, Jerome; Jonckheere, Thibaut; Martin, Thierry [Aix Marseille Universite, CNRS, CPT, UMR 7332, Marseille (France); Universite de Toulon, CNRS, CPT, UMR 7332, La Garde (France); Grenier, Charles; Ferraro, Dario; Degiovanni, Pascal [Universite de Lyon, Federation de Physique Andre Marie Ampere, CNRS - Laboratoire de Physique de l' Ecole Normale Superieure de Lyon, Lyon (France)

2014-01-15

The edge channels of the quantum Hall effect provide one dimensional chiral and ballistic wires along which electrons can be guided in an optics-like setup. Electronic propagation can then be analyzed using concepts and tools derived from optics. After a brief review of electron optics experiments performed using stationary current sources which continuously emit electrons in the conductor, this paper focuses on triggered sources, which can generate on-demand a single particle state. It first outlines the electron optics formalism and its analogies and differences with photon optics and then turns to the presentation of single electron emitters and their characterization through the measurements of the average electrical current and its correlations. This is followed by a discussion of electron quantum optics experiments in the Hanbury-Brown and Twiss geometry where two-particle interferences occur. Finally, Coulomb interactions effects and their influence on single electron states are considered. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electron quantum optics in ballistic chiral conductors

International Nuclear Information System (INIS)

Bocquillon, Erwann; Freulon, Vincent; Parmentier, Francois D.; Berroir, Jean-Marc; Placais, Bernard; Feve, Gwendal; Wahl, Claire; Rech, Jerome; Jonckheere, Thibaut; Martin, Thierry; Grenier, Charles; Ferraro, Dario; Degiovanni, Pascal

2014-01-01

The edge channels of the quantum Hall effect provide one dimensional chiral and ballistic wires along which electrons can be guided in an optics-like setup. Electronic propagation can then be analyzed using concepts and tools derived from optics. After a brief review of electron optics experiments performed using stationary current sources which continuously emit electrons in the conductor, this paper focuses on triggered sources, which can generate on-demand a single particle state. It first outlines the electron optics formalism and its analogies and differences with photon optics and then turns to the presentation of single electron emitters and their characterization through the measurements of the average electrical current and its correlations. This is followed by a discussion of electron quantum optics experiments in the Hanbury-Brown and Twiss geometry where two-particle interferences occur. Finally, Coulomb interactions effects and their influence on single electron states are considered. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

78 FR 39710 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2013-07-02

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78 FR 54235 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2013-09-03

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78 FR 33061 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2013-06-03

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Gauge-invariant area distributions for semiclassical magnetotransport through ballistic nanostructures

International Nuclear Information System (INIS)

Wirtz, L.; Yang, Xiazhou; Burgdoerfer, J.E.

1996-01-01

Within the semiclassical theory of magnetotransport, conductance fluctuations in ballistic cavities are determined by distribution functions of directed areas enclose by classical paths. The authors calculate gauge invariant areas which can be visualized as closure of areas by adding a virtual path to the real path connecting the leads. Gauge invariance of the resulting area distribution is found to be important for geometry-sensitive non-universal properties of transport. The authors show that in the presence of direct paths both the area distribution and the two-point pair distribution function for areas of trajectories contribute. Comparison with recent data by Marcus et al. for a stadium-shaped nanostructure is made

A common control signal and a ballistic stage can explain the control of coordinated eye-hand movements.

Science.gov (United States)

Gopal, Atul; Murthy, Aditya

2016-06-01

Voluntary control has been extensively studied in the context of eye and hand movements made in isolation, yet little is known about the nature of control during eye-hand coordination. We probed this with a redirect task. Here subjects had to make reaching/pointing movements accompanied by coordinated eye movements but had to change their plans when the target occasionally changed its position during some trials. Using a race model framework, we found that separate effector-specific mechanisms may be recruited to control eye and hand movements when executed in isolation but when the same effectors are coordinated a unitary mechanism to control coordinated eye-hand movements is employed. Specifically, we found that performance curves were distinct for the eye and hand when these movements were executed in isolation but were comparable when they were executed together. Second, the time to switch motor plans, called the target step reaction time, was different in the eye-alone and hand-alone conditions but was similar in the coordinated condition under assumption of a ballistic stage of ∼40 ms, on average. Interestingly, the existence of this ballistic stage could predict the extent of eye-hand dissociations seen in individual subjects. Finally, when subjects were explicitly instructed to control specifically a single effector (eye or hand), redirecting one effector had a strong effect on the performance of the other effector. Taken together, these results suggest that a common control signal and a ballistic stage are recruited when coordinated eye-hand movement plans require alteration. Copyright © 2016 the American Physiological Society.

78 FR 25423 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2013-05-01

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78 FR 13858 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2013-03-01

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77 FR 59894 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

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2012-10-01

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Analytical Model of Subthreshold Drain Current Characteristics of Ballistic Silicon Nanowire Transistors

Directory of Open Access Journals (Sweden)

Wanjie Xu

2015-01-01

Full Text Available A physically based subthreshold current model for silicon nanowire transistors working in the ballistic regime is developed. Based on the electric potential distribution obtained from a 2D Poisson equation and by performing some perturbation approximations for subband energy levels, an analytical model for the subthreshold drain current is obtained. The model is further used for predicting the subthreshold slopes and threshold voltages of the transistors. Our results agree well with TCAD simulation with different geometries and under different biasing conditions.

The Effects of PMMA on Ballistic Impact Performance of Hybrid Hard/Ductile All-Plastic- and Glass-Plastic-Based Composites

National Research Council Canada - National Science Library

Hsieh, Alex

2004-01-01

... life cycle costs for the soldiers and ground vehicle protection. The focus of this research is to identify the material parameters that are critical for the ballistic performance of hybrid hard/ductile laminate systems...

Sensitivity Analysis and Mitigation with Applications to Ballistic and Low-thrust Trajectory Design

Science.gov (United States)

Alizadeh, Iman

The ever increasing desire to expand space mission capabilities within the limited budgets of space industries requires new approaches to the old problem of spacecraft trajectory design. For example, recent initiatives for space exploration involve developing new tools to design low-cost, fail-safe trajectories to visit several potential destinations beyond our celestial neighborhood such as Jupiter's moons, asteroids, etc. Designing and navigating spacecraft trajectories to reach these destinations safely are complex and challenging. In particular, fundamental questions of orbital stability imposed by planetary protection requirements are not easily taken into account by standard optimal control schemes. The event of temporary engine loss or an unexpected missed thrust can indeed quickly lead to impact with planetary bodies or other unrecoverable trajectories. While electric propulsion technology provides superior efficiency compared to chemical engines, the very low-control authority and engine performance degradation can impose higher risk to the mission in strongly perturbed orbital environments. The risk is due to the complex gravitational field and its associated chaotic dynamics which causes large navigation dispersions in a short time if left un-controlled. Moreover, in these situations it can be outside the low-thrust propulsion system capability to correct the spacecraft trajectory in a reasonable time frame. These concerns can lead to complete or partial mission failure or even an infeasible mission concept at the early design stage. The goal of this research is to assess and increase orbital stability of ballistic and low-thrust transfer trajectories in multi-body systems. In particular, novel techniques are presented to characterize sensitivity and improve recovery characteristics of ballistic and low-thrust trajectories in unstable orbital environments. The techniques developed are based on perturbation analysis around ballistic trajectories to

An anthology: Rationale for a US ballistic missile defense (1969 - 1984)

Science.gov (United States)

Tircuit, E. C.

1985-04-01

This anthology is a selection and short synopsis of representative articles on the rationale for a US ballistic missile defense (BMD). Unclassified articles and documents were reviewed and analyzed to identify and include nine representative articles in the anthology. The anthology reduces the search for quality material on the subject and documents the fundamental rationale for a BMD. The author concluded that the fundamental rationale for a US BMD is to deter nuclear war. In addition, specific rationale for a US BMD is provided in the anthology. Finally, an extensive bibliography is included in the anthology to enhance further research on the subject.

Reassessing the Representative Heuristic of the Plywood Ballistic Mannequin Used in Live-Fire Testing

Science.gov (United States)

2015-04-01

robust design. According to M Mahaffey, “It is not the purpose of modeling to design the system, but rather to generate data to motivate robust design...decisions.”1 So, amidst the systemic error, competing priorities, and uncertainties, how do the analysts ensure they are not nudging these robust...Conclusions The plywood ballistic mannequins are a blunt tool because of the low reliability in the definition of possible personnel. Employed