Ballistic Calculations Research Articles

Performance Enhancement Technique to Incorporate Muzzle Reference Data in the Ballistic Computer

During last two decades fire control system of tanks had made a rapid progress due to incorporation of ballistic computer and advancements in electronics technologies. Different techniques had been evolved to automate the fire control system. The aim of this paper is to modify the ballistic equation by including the muzzle reference data in the tank ballistic computer. The results have shown significant improvement in the accuracy of the fire control system of the battle tank.

Research on the Ballistic Model and Simulation of a Ejection Cylinder

To analyze the ballistic characteristics of ejection cylinder in falling stage, the dynamic characteristics of ejection cylinder and parachute are analyzed. Based on force bearing analysis, the particle ballistic model of ejection cylinder and parachute in falling stage are built, and the ballistic data is simulated. The results shows that the ballistic model is reasonable and better simulate ballistic characteristics of ejection cylinder in falling stage. The results can be used to ballistic calculation and determinate the fire data.

A ballistics module as a part of the fire control system

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 fuse is activated. The initial elevation of the tools that is used for calculating the trajectory to the end point should also be determined. The calculation is repeated until the final point of the trajectory coincides with a specific point by a projectile. During the preparation phase of fire, after all input parameters have been defined, the calculation is activated by the appropriate command. As an output from the BM, the initial firing data for the battery are determined: - Type of projectile, type of fuse, angle, distance table, locating devices and timing device (or the flight time); - Information and data: ordinate trajectory, angle of fall, terminal velocity, probable error of range and probable error of deflection. The demands placed on the ballistic module: In order to perform the functions of fire, the BM should provide, in addition to determining the elements for target practice, the solution to the following tasks: - Check the possibility to fire; - Correction and transfer of fire; - Group shooting, and - Planned fire. Ballistic testing of module: All ballistic modules (ballistic model, ballistic data, ballistic module software and the hardware that they will be implemented on) should meet the established requirements. The ballistic testing of the module is done in several stages, using a ballistic computer (BC) simulation model, the entire artillery system simulation program and the computer embedded in the target system. The ballistic computer simulation model allows input of all projected input data and displaying all the results of calculations in a batch and interactive mode. The ballistic model and ballistic data are tested by comparing them with the verification data obtained from simulation programs or parts of programs used for creating firing tables. Conclusion: Modern combat conditions impose increasing the efficiency and effectiveness of artillery fire by increasing the speed of response and shooting accuracy. The approximate methods used in the first stage of artillery computers inevitably caused inaccuracy of such data as well as a number of corrections, which increased the time required for firing at goal. In accordance with international standards, a module for calculating firing elements in the fire control system must be implemented by the same trajectory model and with the same ballistic data for the weapon and ammunition as well as in the procedure for the preparation of firing tables. Technological advances in hardware implementation ensure the implementation of such software. From the above mentioned reasons, the realized ballistic BM module shows the following benefits of the fire control system: significant increase of the speed, accuracy and efficiency of artillery fire, reduction of the number of persons required to perform its functions and a higher technological level.

Digital Design and Performance Evaluation of the Rocket Engine

In order to achieve the digital design of solid rocket motors, the MFC module of Visual Studio2010 is used for interface software programming in this paper. Beginning with the initial performance parameters, the software receives the input parameters and gives the results of grain design and its interior ballistic calculation. Given all the results, we can evaluate the performance of grain. The design cases show that the design results of the software are correct and reliable.

Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling

Within an effective Dirac theory the low-energy dispersions of monolayer graphene in the presence of Rashba spin-orbit coupling and spin-degenerate bilayer graphene are described by formally identical expressions. We explore implications of this correspondence for transport by choosing chiral tunneling through pn and pnp junctions as a concrete example. A real-space Green's function formalism based on a tight-binding model is adopted to perform the ballistic transport calculations, which cover and confirm previous theoretical results based on the Dirac theory. Chiral tunneling in monolayer graphene in the presence of Rashba coupling is shown to indeed behave like in bilayer graphene. Combined effects of a forbidden normal transmission and spin separation are observed within the single-band n to p transmission regime. The former comes from real-spin conservation, in analogy with pseudospin conservation in bilayer graphene, while the latter arises from the intrinsic spin-Hall mechanism of the Rashba coupling.

First-principles study of ballistic transport properties in Co2MnSi/X/Co2MnSi(001) (X=Ag, Au, Al, V, Cr) trilayers

We investigate and discuss the origin of interface resistance in magnetic trilayers with the half-metallic Co${}_{2}$MnSi by performing first-principles electronic-structure and ballistic transport calculations for Co${}_{2}$MnSi/$X/$Co${}_{2}$MnSi(001) ($X=$ Ag, Au, Al, V, Cr). We found that the matching of the Fermi surface projected to the two-dimensional Brillouin zone of in-plane wave vector (${k}_{\ensuremath{\parallel}}$) is a main contributing factor for the spacer ($X$) dependence of the interfacial resistance. Furthermore, the MnSi-terminated interface shows low resistance compared with the Co-terminated interface because the Co-terminated interface has a larger $d$ component in the local density of states at the Fermi level than that of the MnSi-terminated interface. We conclude that Ag, Au, and Al spacers with MnSi termination of CMS$/X/$CMS trilayers will provide the large interfacial spin-asymmetry coefficient because of the small interface resistance in parallel magnetization.

A ballistic limit analysis programme for shielding against micrometeoroids and orbital debris

A software programme has been developed that enables the user to quickly and simply perform ballistic limit calculations for common spacecraft structures that are subjected to hypervelocity impact of micrometeoroid and orbital debris (MMOD) projectiles. This analysis programme consists of two core modules: design and performance. The design module enables a user to calculate preliminary dimensions of a shield configuration (e.g. thicknesses/areal densities, spacing, etc.) for a “design” particle (diameter, density, impact velocity, and incidence). The performance module enables a more detailed shielding analysis, providing the particle size that is “stopped” by a user-defined shielding configuration over the range of relevant in-orbit impact conditions.

Ballistic Comparative Study of Three Automatic Rifle Calibers

Calibers 7.62×39 mm and 5.56×45 mm are the two famous automatic rifle calibers used worldwide by infantry soldiers. Several years ago, most of European and American countries already changed from 7.62×39 mm to 5.56×45 mm, while other countries still using caliber, 7.62×39 mm and refusing the change. To optimize the advantages of both calibers, anew automatic rifle caliber 6.8×43 mm emerges. The purpose of this study is to perform a ballistic comparative study of the three mentioned calibers. Interior ballistic calculations were performed using modified Charbonnier semiempiricalmodel to estimate the weapon interior ballistic parameters. While, the main task of exterior ballistics (i.e., projectile trajectory parameters and energy dissipation during projectile flight at different firing angles) was performed using point-mass two-degree-offreedom trajectory model. It was found that the value of maximum pressure of gases inside the rifles barrel were almost the same, while three different muzzle energies were obtained. They are 2.45 kJ for 6.8×43mm, 2.1 kJ for 7.62×39 mm, and 1.55 kJ for 5.56×45 mm. The highest energy dissipation along the trajectory was found with 6.8×43 mm projectile. The lowest one was found with 5.56×45 mm projectile all over the range of angles of fire.

An integrated approach for optimization of solid rocket motor

An integrated approach using hyper-heuristic based on meta-heuristics is applied in optimization of solid rocket motor. We propose a non-learning random function to control low-level meta-heuristics to increase certainty of global solution. A comprehensive empirical study investigates the performance of the proposed algorithm yielding satisfactory results. Design of solid rocket motor becomes an exigent task when accounting for chamber design, nozzle design, ballistic performance calculations as well as grain geometry and regression. CAD modeling overcomes the limitation posed by analytical expression thus increased model fidelity. CAD model allows different sub-systems to be modeled separately that not only prevents feature creation failures but also allows ease in modification of the model. Motor performance is calculated using a simplified ballistic model. Mass is the impetus driver on performance, and so considered as core of solid rocket motor design process. Therefore, we intend to minimize gross mass through hyper-heuristic approach. The approach produced satisfactory results for test case.

Pistol thrown to the ground by shooter after fatal self inflicted gunshot wound to the chest

We report the case of a 46-year-old man found dead in his apartment in a chair with a gunshot wound in his chest. All circumstances pointed to suicide as the manner of death. Finding the weapon, a SIG Sauer P228 pistol, about 2 m away from the decedent with an obstacle between weapon and corpse however generated speculation about third party involvement. Scene investigations and ballistic calculations showed that with a high probability the weapon must have been purposefully thrown away by the decedent after he fired the lethal gunshot.

Mechanism of large magnetoresistance inCo2MnSi/Ag/Co2MnSidevices with current perpendicular to the plane

Fully epitaxial current-perpendicular-to-plane giant magnetoresistance (MR) devices with half-metallic ${\text{Co}}_{2}\text{MnSi}$ (CMS) electrodes and a Ag spacer were fabricated to investigate the relationship between the chemical ordering in CMS and its MR properties, including bulk and interface spin-asymmetry coefficients $\ensuremath{\beta}$ and $\ensuremath{\gamma}$. CMS/Ag/CMS annealed at $550\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ shows the largest MR ratio: 36.4% and 67.2% at RT and 110 K, respectively. An analysis based on Valet-Fert's model reveals large spin asymmetry $(\ensuremath{\gamma}>0.8)$ at the CMS/Ag interface, which contributes predominantly to the large MR ratio observed. First-principles ballistic conductance calculations for (001)-CMS/Ag/CMS predict a high majority-spin electron conductance, which could be the origin of the large $\ensuremath{\gamma}$ observed in this study.

Tailoring tunnel magnetoresistance by ultrathin Cr and Co interlayers: A first-principles investigation of Fe/MgO/Fe junctions

We report on systematic ab initio investigations of Co and Cr interlayers embedded in Fe(001)/MgO/Fe(001) magnetic tunnel junctions, focusing on the changes in the electronic structure and the transport properties with interlayer thickness. The results of spin-dependent ballistic transport calculations reveal options to specifically manipulate the tunnel magnetoresistance ratio. The resistance-area products and the tunnel magnetoresistance ratios show a monotonous trend with distinct oscillations as a function of the Cr thickness. These modulations are directly addressed and interpreted by means of magnetic structures in the Cr films and by complex band-structure effects. The characteristics for embedded Co interlayers are considerably influenced by interface resonances which are analyzed by the local electronic structure.

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

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.

Analysis of spin transfer torque in Co/Cu/Co pseudo-spin-valve with perpendicular magnetic anisotropy

Abstract Perpendicular-magnetized pseudo-spin-valves (PSV) boast the advantages of lower aspect ratio, greater magnetic stability and thermal stability; and hence constitute a promising candidate for achieving higher integration area density. In this paper, we investigate the spin transport and spin transfer torque in a Co/Cu(1 1 1)/Co perpendicular PSV structure where the magnetization of the Co layers are oriented in the out-of-plane direction, in the presence of a spin-polarized current in the perpendicular-to-plane (CPP) geometry. Both ballistic spin-dependent transmission/reflection at the two Co–Cu interfaces and diffusive spin relaxation within the Co and Cu layers are considered in our model. The ballistic calculations predict an absorbed spin current component at the Cu-free Co interface, which constitutes the main source (∼90%) of the total spin transfer torque in the free Co layer. The remaining torque arises from the spin relaxation of transmitted spin current within the free Co layer. Our model predicts a lower range of the critical current density of less than 107 A/cm2 for perpendicularly magnetized PSVs, while that for in-plane magnetized PSVs is of the order of several 107 A/cm2. Additionally, perpendicularly magnetized PSVs also possess other practical advantages which make them promising candidates for future MRAM applications.

Graphene interferometer

Ballistic transport calculations, which are treated exactly within the nearest-neighbor tight-binding theory, on graphene strips connected to a pair of contacts are presented. In strips with high width-to-length ratio, the calculations reveal the presence of groups of resonances from a large number of nonequivalent conductance channels. While the energies of the collective resonances are, to first order, uniformly spaced and only depend on the contact separation, their contrast also depends on the strip width and contact interfaces.

Magnetic phenomena, spin-orbit effects, and Landauer conductance in Pt nanowire contacts: Density-functional theory calculations

Platinum monatomic nanowires were predicted to spontaneously develop magnetism, involving a sizable orbital moment via spin-orbit coupling, and a colossal magnetic anisotropy. We present here a fully-relativistic (spin-orbit coupling included) pseudopotential density functional calculation of electronic and magnetic properties, and of Landauer ballistic conductance of Pt model nanocontacts consisting of short nanowire segments suspended between Pt leads or tips, represented by bulk planes. Even if short, and despite the nonmagnetic Pt leads, the nanocontact is found to be locally magnetic with magnetization strictly parallel to its axis. Especially under strain, the energy barrier to flip the overall spin direction is predicted to be tens of meV high, and thus the corresponding blocking temperatures large, suggesting the validity of static Landauer ballistic electrical conductance calculations. We carry out such calculations to find that inclusion of spin-orbit coupling and of magnetism lowers the ballistic conductance by about $15\textdiv{}20%$ relative to the nonmagnetic case, yielding $G\ensuremath{\sim}2{G}_{0}$ $({G}_{0}=2{e}^{2}/h)$, in good agreement with break junction results. The spin filtering properties of this highly unusual spontaneously magnetic nanocontact are also analyzed.

Determination of the dispersive elastic constants of the cubic crystals Ge, Si, GaAs, and InSb

The first onset of spatial dispersion, i.e., the variation of velocity of an elastic wave when its wavelength approaches the natural scale of length of a medium, can be accommodated within continuum elasticity theory by the incorporation of third and fourth order spatial derivatives of the displacement field in the elastic wave equation. This paper is concerned with the access to the coefficients of these higher order derivatives in gradient elasticity provided by inelastic neutron scattering, ballistic phonon imaging, and picosecond laser ultrasound measurements. Numerical values of the dispersive elastic constants of the four cubic crystals, germanium, silicon, gallium arsenide, and indium antimonide, are obtained by fitting to available near zone center symmetry direction acoustic mode phonon dispersion relations of these crystals, measured by inelastic neutron scattering. Ballistic phonon transport calculations using these values, account well for available dispersive phonon images of these crystals. For Ge, Si, and GaAs, comparison is made with values of dispersion coefficients reported elsewhere in literature, which have been obtained from laser ultrasound measurements and from empirical and ab initio lattice dynamics models.

포 구동명령 개선을 위한 표적상태 추정기 설계

This paper presents a target sate estimator(TSE) with low pass filter for improving the gun driving command. The ballistic computer uses target information such as predicted range, velocity, acceleration of a target to generate the gun command. We adopt the finite impulse response(FIR) filter as our TSE to shorten calculation time for the driving command and due to its inherent stability property. We also introduce a post-processing filter to reduce the high frequency components in the output signal of a TSE which may cause instability of gun driving. The first order low pass filter has been designed based on <TEX>$H{\infty}$</TEX> criteria considering the noise characteristics. To show the validity of the present scheme, simulation results are given for the overall gun driving system including aircraft target information.

Effect of the density of collision cascades on ion implantation damage in ZnO

We study structural disorder in ZnO bombarded at room temperature with 1.3 keV∕amu atomic P and cluster PFn (n=2 and 4) ions. Rutherford backscattering/channeling spectrometry results show that the density of collision cascades has a negligible effect on the damage buildup in the crystal bulk in the dose range resulting in ∼1.5−15 displacements per atom. Hence, the amount of stable post-implantation disorder in the bulk can be predicted based on ballistic calculations. In contrast, the cascade density affects radiation damage in the near-surface region. An intermediate defect peak between the expected surface and bulk peaks of disorder forms for ion irradiation conditions with dense cascades.

Ballistic conductance calculation of atomic-scale nanowires of Au and Co

Ballistic conductance calculations on infinite one-atom zigzag chains of Co and Au, andmulti-atom Au nanowires, were computed using the Landauer–Büttiker formalismwithin the local-density approximation (LDA). In the cobalt case, the majorityspin channel exhibits quantized conductance, but because of the close spacingof the d levels, the minority channel does not. The calculated conductance issomewhat larger than what is observed. We suggest that the discrepancy is anindication that the Landauer–Büttiker formalism breaks down in this narrow d bandmaterial. In contrast, Au (which was determined not to be spin polarized) does showwell-behaved quantization in the case of the infinite zigzag chain. By increasing thedimension of the cross section of the chain, we find that quantization is lost once thelateral dimensions of the wire exceed two or so atoms. Finally, we show that thezigzag chain of Au can have a Peierls instability, making the chain insulating.