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An analytical-experimental method has been used to investigate the penetrative capability of cylindrical VNZh-90 and VNZhK + 75% VK8 with flat heads and conical noses in interaction with a steel barrier in the velocity range of 1200–1300 m/s. Calculation results are presented for interaction of the considered strikers with steel barriers at impact velocities of up to 2000 m/s. [ABSTRACT FROM AUTHOR]

An experimental and theoretical study of the combustion of granulated charges consisting of pyroxylin powders in a manometric bomb of constant volume is presented. A comparison was made of the experimentally measured dependence of pressure increase in a manometric bomb with calculations according to thermodynamic model of combustion of a gunpowder sample in a manometric bomb using the empirical law of the dependence of the burning rate on pressure and a conjugate model of unsteady combustion of gunpowder. The unsteady rate of burning of pyroxylin powder, due to the high rate of pressure growth in the manometric bomb, differs from the quasi-stationary speed. This difference depends on the rate of pressure growth and on its absolute value and decreases with increasing pressure. [ABSTRACT FROM AUTHOR]

Results have been presented of intraballistic design work aimed at identifying the main characteristics of a small caliber laboratory launcher and the composition of the propellant charge for various striker masses. Technical solutions have been obtained for sabots of supercavitating strikers accelerated in a small size laboratory ballistic installation. The level of the pressure acting on the striker, as it enters the water directly from the barrel of the installation, has been determined. Travel path ranges have been calculated for supercavitating strikers accelerated in a small size laboratory ballistic installation. [ABSTRACT FROM AUTHOR]

A promising direction in barrel ballistics aimed at increasing the muzzle velocity of a projectile is the use of new propellants as an attached charge. This paper presents an experimental and theoretical method for determining the law of propellant combustion in a manometric experiment (in a closed volume). Within the framework of this method, a small number of experiments could be sufficient to determine a change in the law of combustion during the propellant burnout and depending on pressure. This method is demonstrated on the example of processing three experiments with model high-density propellant. The laws of combustion of high-density propellants, obtained in this study, can later be used to calculate the gas-dynamic parameters of a shot from a barrel system or a nozzle bomb (in a semi-closed volume) using these propellants. [ABSTRACT FROM AUTHOR]

The combustion of a model high-density propellant (MHP) under the conditions of a closed volume has been investigated. A description is given of the main components and mechanisms of the manometric bomb being used. Procedures are described for determining the laws of propellant combustion in a manometric experiment, and a comparison is made of computational-experimental data. The distinctive features of the formation of an MHP combustion surface in various containers have been identified and described. The dependences of the layer combustion velocity of two model high-density propellants on pressure have been determined. [ABSTRACT FROM AUTHOR]

Experimental-theoretical investigations have been conducted into underwater supercavitating motion of cone strikers from various materials in a broad range of velocities. An estimate of the range of strikers' velocities has been performed for the implementation of their nondestructive entry into water and motion in it in a supercavitating regime. A possibility of an accurate hit by supercavitating strikers on underwater barriers in a supersonic range of motion velocities has been shown. [ABSTRACT FROM AUTHOR]

The interaction of supercavitating strikers with obstacles placed in water was investigated in a wide range of intersection angles. Several options of the interaction of strikers with obstacles are considered, including through puncturing, destruction of the striker, and ricochet. Estimation was made of the magnitude of the decrease in the speed of strikers in the cases of through puncturing and ricochet. [ABSTRACT FROM AUTHOR]

Results of a complex experiment-calculated investigation of the structure of a nonstationary gas flow in the working path of a hypersonic ramjet engine are presented. Methods of experimental determining the pressure and temperature distributions over the wall of an axisymmetric channel of complex geometry with a sudden widening are proposed and described. The problem on the gas flow over a ramjet engine positioned in a wind tunnel was solved. [ABSTRACT FROM AUTHOR]

Using the computer-based simulation method within the scope of continuous mechanics, impact interaction with a speed of 3000 m/s between a steel ball and a transparent armor target is calculated (the target has three layers). The face layer of the transparent armor is made of aluminum oxynitride; the middle layer, of hardened glass; and the lower layer, of polycarbonate. The influence of the angle of the projectile approach to the target and thickness of the hardened glass layer on the process of target penetration is studied. [ABSTRACT FROM AUTHOR]

An experimental procedure has been developed to record phenomena in impact destruction of a container with a fluid. The phenomena were recorded using x-ray pulse devices and a high-speed filming technique. The propagation of compression waves in the fluid was registered using bubble-markers in the form of air curtains in the fluid mass. The pressure in the compression wave was measured by a gallium arsenide crystal-based sensor. An investigation has been made into the characteristics of the phenomena occurring during the destruction of a container with a fluid by a high-speed striker. We have established the dependences of cavity development in the fluid, the striker motion law, the time dependence of pressure, and the pressure attenuation in the fluid. The obtained dependences make it possible to establish objective physical data on phenomena in impact-stressed containers and to solve the issue of strength of a container with a fluid. [ABSTRACT FROM AUTHOR]

Problem-based questions (PBQs) are mastered in the process of learning the subject matter and developing the ability to think. Constructing PBQs enabled students to develop their ability to consciously handle notions, formulate statements, make conclusions, and reveal contradictions. The ability to operate a system of notions while posing questions and looking for answers to them encourages meaningful communication. The findings were used to develop and implement an advanced training course for university teachers. The booster of theoretical thinking helps to switch from declarative knowledge given by a teacher to its joint discovery with learners. [ABSTRACT FROM AUTHOR]

Using high-temperature sintering, tungsten-carbide alloy-based specimens with improved functional properties have been explored. The penetrative capability of strikers fabricated of these samples into a steel barrier at an interaction speed of 1300 m/s has been investigated in comparison with that of the mass and size of a VNZh-90 alloy-based analogue. [ABSTRACT FROM AUTHOR]

The investigation is devoted to an experimental and theoretical research into the high-velocity motion of a group of supercavitating kinetic strikers in water. An experimental launching technique has been developed, and investigations have been conducted into the high-velocity motion of a group of supercavitating strikers on a hydroballistic testing facility, and a calculation procedure has been developed for modeling possible deviations of the strikers′ motion in water in a group start. Experimental data have been obtained on the motion of one and two supercavitating strikers on the initial portion of the path at velocities of the order of 1200 m/s, which serve as initial conditions for identifying the strikers' deviation from the target at a distance of up to 100 m. [ABSTRACT FROM AUTHOR]

The ballistic resistance of a combined cermet material based on a high-hardness ceramic bound with an intermetallide on a high-strength metal substrate, (TiB2 + NiTi) + Ti, is compared with that of plates of steel, VT1-0 titanium alloy, and Al2O3 corundum ceramics upon an impact with a steel spherical impactor in the region of velocities of about 2500 m/s. Experimental studies of protective barriers upon a high-speed impact were conducted using an experimental high-speed ballistic test bench. Mathematical modeling is based on a model of porous elastoplastic medium with allowance for various mechanisms of material destruction, which was modified for media with a complex composition. It is shown that, in the considered range of impact velocities, during penetration of barriers, the (TiB2 + NiTi) + Ti material, despite its low surface density, exerts a greater force on the impactor and exhibits greater penetration resistance than steel, titanium, and ceramics. [ABSTRACT FROM AUTHOR]

On the basis of an experimental and theoretical approach, the authors have considered an algorithm for modeling the behavior of advanced propellants in barreled systems of varying caliber. The proposed algorithm makes it possible to conduct preliminary investigations into the possibility of using advanced fast-burning propellants in the existing barreled systems and in advanced systems of varying calibers and for various purposes. A possible increment in the muzzle velocity of a projectile due to the advanced propellants added to the propellant powder charge is assessed without full-scale testing. [ABSTRACT FROM AUTHOR]

We propose a series of experiments aimed at analysis of peculiarities and revealing general regularities in the penetrability of strikers made of a composite material based on tungsten + nickel + iron + cobalt alloy with an admixture of highly rigid refractory titanium–tungsten carbide particles in various initial conditions. In particular, we have analyzed the effect of the initial temperature of the striker in the interval from –50 to 50°C on the penetration into a steel obstacle experimentally and by calculations. It is found that the initial temperature of the striker does not noticeably affect the penetration depth in the obstacle at impact velocities up to 2500 m/s. The penetrability is found to be 20% higher than that for a monolithic massive analog made of VNZh-90 alloy. [ABSTRACT FROM AUTHOR]

A mathematical model of a shot from a smoothbore ballistic installation for a gun start of a group of supercavitating strikers has been developed. To verify the mathematical model, experimental investigations into high-velocity launching of a group of bodies on a hydroballistic testing facility have been conducted. A comprehensive parametric investigation has been conducted to determine conditions for loading the ballistic installation to achieve the required muzzle velocity, ensuring a supercavitating regime of motion for a group of strikers in water. [ABSTRACT FROM AUTHOR]

In this study, we perform calculations and experimental studies of the destruction of composite impactors from a porous tungsten–nickel–iron–cobalt alloy with 10 wt % tungsten titanium carbide at high-speed impact with steel barriers. In ballistic tests over a wide range of velocities, there is a significant excess of the penetration depth of these impactors into steel barriers compared to the mass-dimensional analog of a tungsten–nickel–iron alloy with 90% tungsten content. Based on the analysis of crater morphology and the structure of impactor fragments after introduction into the obstacle, we assume that the impactor is "self-sharpened" by localizing plastic deformation, which reduces the effective interaction area and increases the penetration depth. To describe the destruction, we modified the mathematical model of a porous ideal elastic-plastic body with a complex structure with the possibility of considering the adiabatic shear mechanism during interaction between the impactor and the obstacle. [ABSTRACT FROM AUTHOR]

The paper is devoted to the investigation of the high-velocity motion of supercavitating kinetic strikers in water with account of the intraballistic processes in the powder chamber and outside the channel cut of the ballistic installation, the supercavity dynamics, and also the interaction of the strikers with underwater barriers (obstacles). The process of supercavitating motion at underwater start is modeled on the basis of solving Reynolds-averaged Navier–Stokes equations with turbulence equations and cavitation equations for a multiphase medium. To investigate the stressstrain state and a possible destruction of solid bodies in interacting with underwater barriers of various types, mathematical modeling is conducted on the basis of an elastoplastic model of a medium. The range of investigated velocities is 50–850 m/s. [ABSTRACT FROM AUTHOR]

High-velocity motion of a set of supercavitating kinetic strikers during their simultaneous entry into water has been experimentally studied. A special experimental method of launching supercavitating kinetic strikers and studying their high-velocity motion under hydroballistic test setup conditions has been developed. Experimental data on the motion of two identical supercavitating strikers in the initial stage of trajectory at velocities about 1100 m/s have been obtained, which demonstrate the possibility of stable propagation of a set of such strikers in water until reaching an underwater target. [ABSTRACT FROM AUTHOR]

An experimental-theoretical assessment has been made of the minimum required velocity for through penetration of 20–60 mm thick steel barriers by a supercavitating VNZR-95 alloy striker. Parametric calculations have been conducted within the framework of an elastic-perfect plastic Prandtl–Reuss model. [ABSTRACT FROM AUTHOR]

High-temperate vacuum sintering has been used to obtain porous composite tungsten carbide alloy TNIC (W–Ni–Fe–Co) + 69 wt.% WC. The results of investigations into the microstructure and physical-mechanical properties of the alloy are presented. An experimental investigation has been conducted into the high-velocity interaction of cylindrical strikers made of this material with steel plates in the velocity range of 1200–1400 m/s. [ABSTRACT FROM AUTHOR]

A series of high-voltage (20–50 kV) DC power sources (1–10 kW) was developed based on the circuit of high-frequency conversion with wide-range regulation of the output voltage via conversion frequency tuning. A sinusoidal current shape provides switching of power transistors at the zero current and the short-circuit protection in a load. The source provides an output voltage with small ripples and, when powered from a three-phase network, it does not require a smoothing mains filter. [ABSTRACT FROM AUTHOR]

Results of a complex experiment-calculated investigation of the structure of a nonstationary gas flow in the working path of a hypersonic ramjet engine are presented. Methods of experimental determining the pressure and temperature distributions over the wall of an axisymmetric channel of complex geometry with a sudden widening are proposed and described. The problem on the gas flow over a ramjet engine positioned in a wind tunnel was solved. [ABSTRACT FROM AUTHOR]

Aminomethylation of harmol (7-hydroxy-1-methyl-β-carboline) was investigated. It was shown that the reaction proceeds chemoselectively to form 8-aminomethyl derivatives by the action of aminals or a mixture of a secondary amine with paraform. When primary amines and an excess of paraform were used in the Mannich reaction, 2,3-dihydro-1H-pyrido[4',3':4,5]pyrrolo[3,2,1-ij]quinazolin-4-ol and 1,2,3,11-tetrahydro[1,3]oxazino[6,5-g]pyrido[3,4-b]indole derivatives are formed. [ABSTRACT FROM AUTHOR]

The paper studies the behavior of ceramic porous tungsten alloy with reinforcing agents under the shock-wave loading conditions. Penetrating capacity of tungsten kinetic energy projectiles is calculated and experimentally investigated during their high-speed impacts on steel plates. It is shown that the increased penetration depth of tungsten projectiles exceeds that of the prototype with relevant weight and size, made of tungsten-nickel-iron cast alloy. A mathematical model is developed together with the design technique of the behavior of tungstennickel-iron-cobalt metal foams alloyed with boron carbide, tungsten titanium carbide and tungsten carbide during the high-speed impact interaction. The composite ceramic material is described here as a porous medium. The matrix of this medium is a homogeneous two-phase mixture of the tungsten-nickel-iron-cobalt system and reinforcing agents added in the required proportions. [ABSTRACT FROM AUTHOR]

The possibility of improving the physico-mechanical characteristics of composite materials used in protective structures against a high-speed impact is considered. By means of self-propagating high-temperature synthesis, a two-layer cermet is obtained: the front layer is a cermet based on titanium diboride with a titanium nickelide bond, and the back layer is a titanium alloy. The study by the computational-experimental method of the impact resistance of this composite in comparison with a homogeneous titanium plate showed a qualitative advantage expressed in the absence of a shock crater in a cermet plate after a collision with a steel spherical impactor and stronger deformation and prefracture of the impactor. The two-layer cermet has a high resistance to the penetration of the steel impactor. [ABSTRACT FROM AUTHOR]

Peculiarities of the motion of one and two supercavitating strikers in water upon their simultaneous entry into water at speeds exceeding the speed of sound in the medium are considered. Conditions have been developed to ensure nondestructive entry of strikers into the water and stable movement along an aiming trajectory in the transonic speed range. A stable joint motion of two strikers in water at supersonic speed is obtained. [ABSTRACT FROM AUTHOR]

An attempt is made to create an electric-discharge source for pumping argon, krypton, and xenon dimer lasers. The device is based on a method proposed previously by the authors, wherein confinement of the discharge is achieved by removing the cathode spot from the main discharge region and closing the discharge to the spot along a narrow extended auxiliary plasma channel. The conditions for the formation of such a discharge are investigated. The high stability of the sparkless stage of the discharge permits the first-ever attainment of energy depositions at the level of 100 J/cm² at pressures ∼ 10 atm, a level several orders of magnitude higher than is attainable by conventional methods. A discharge cell and power supply system are designed for a multisectional discharge with an active length of 200 mm, and the reliability of the entire apparatus is demonstrated in long-term use. [ABSTRACT FROM AUTHOR]

This article presents the results of external ballistic investigations of motion in the air of supercavitating strikers cannon-launched in a group, and a gas-dynamical picture of flow past two strikers in the chamber of an aerodynamic installation. Mathematical simulation of the process of flow past two strikers has been carried out, and their aerodynamic coefficients have been calculated. The conditions for cannon-launching of a group of supercavitating strikers have been determined that provide for their motion along the aerodynamic portion of the route and their subsequent entry into water with an angle between the longitudinal axes of strikers, at which their motion is stable. [ABSTRACT FROM AUTHOR]

A mathematical model has been constructed and verified for the behavior of a composite barrier under the conditions of shock-wave loading. An analytical-experimental method has been used to assess the effects of a modified composite barrier in high-velocity interaction with a spherical steel striker in the velocity range of 500–1200 m/s. [ABSTRACT FROM AUTHOR]

Analysis has been made of the ballistic characteristics of the shots, and a powder grade has been indentified for a propellant powder charge ensuring the lowest level of force action on the projectile assembly including a group of supercavitating strikers in a gun-start. [ABSTRACT FROM AUTHOR]

A mathematical model has been constructed for the behavior of a tungsten carbide alloy on the basis of TC8 (tungsten carbide, 92%; cobalt, 8%) and WNFC (W–Ni–Fe–Co), or TNIC (tungsten, nickel, iron, and cobalt), in conditions of shock-wave loading. A scheme has been suggested for the process of mass loss and self-sharpening of the striker in dynamic interaction with the target. The computational-experimental method has been used to investigate the capacity of cylindrical strikers made of this composite to penetrate into a steel target at an impact velocity of 1260 m/s with account for the dependence of yield stress on the intensity of plastic deformation considering both the stage of strengthening and the stage of its structural softening in the process of deformation. [ABSTRACT FROM AUTHOR]

Results are presented of an experimental-theoretical investigation of the motion in water of supercavitating strikers made of steel and aluminum and tungsten (TNI, i.e., tungsten, nickel, and iron) alloys in a broad velocity range. Estimates have been made of the ranges of velocities of entry into water in which the investigated supercavitating strikers from various materials are not destroyed and preserve the original shape. Experimental and computational data have been obtained on the value of deviation of the trajectories of two simultaneously starting from each other supercavitating strikers at the initial stage of their group motion in water depending on the materials they are made of. [ABSTRACT FROM AUTHOR]

The paper presents the methodology elaboration for the investigation of a high-speed impact interaction between the projectile and a split target. The impact interaction speed ranges between 1500 and 2500 m/s. The split target consisting of a polymethyl methacrylate target and a witness target made of D16 aluminum alloy, is placed at a 60 mm distance from the latter. Using mathematical simulation, all effects that occur during the high-speed impact interaction, are analyzed more precisely. [ABSTRACT FROM AUTHOR]

The CH3I A-state-assisted photofragmentation of the (CH3I)2 van der Waals dimer at 248 nm and nearby wavelengths has been revisited experimentally using the time-of-flight mass spectrometry with supersonic and effusive molecular beams and the “velocity map imaging” technique. The processes underlying the appearance of two main (CH3I)2 cluster-specific features in the mass spectra, namely, I2+ and translationally “hot” I+ ions, have been studied. Translationally hot I+ ions with an average kinetic energy of 0.94±0.02 eV appear in the one-quantum photodissociation of vibrationally excited I2+(2Π3/2,g) ions (vib=0.45±0.11 eV) via a “parallel” photodissociation process with an anisotropy parameter β=1.55±0.03. Comparison of the images of I+ arising from the photoexcitation of CH3I clusters versus those from neutral I2 shows that “concerted” photodissociation of the ionized (CH3I)2+ dimer appears to be the most likely mechanism for the formation of molecular iodine ion I2+, instead of photoionization of neutral molecular iodine. [ABSTRACT FROM AUTHOR]

Fluorescence decay of gaseous oxalylfluoride (COF)[sub 2] excited to the A˜ [sup 1]A[sub u](7[sup 1]5[sup 1]) level was measured as a function of gas pressure in absence and in presence of magnetic field, B=0.3 T. On excitation to this level, the dynamics in both zero and nonzero fields may be described in the intermediate-molecule limit, with the fluorescence exhibiting biexponential and triexponential decay, respectively. The fast component decay rate constant k[sub f]=(5.31±0.22)·10[sup 7] s[sup -1] is independent on the (COF)[sub 2] gas pressure or magnetic field strength, while that of the first slow component depends on both. The second slow component lifetime is independent of the field strength, while dependent on the gas pressure. The Stern-Volmer dependence, measured with a field in the 0.3-12 mTorr pressure range, is nonlinear. The results obtained were explained by the indirect (electronic- and nuclear-spin-decoupling) mechanism, proposed earlier. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Consideration is given to conditions ensuring stable high-velocity motion of supercavitating kinetic strikers in water. To investigate the stressed-strained state and a possible destruction of solid bodies during the motion in water and in interaction with underwater barriers of various types, the authors carry out mathematical modeling based on a unified methodological approach of the continuum mechanics. The range of the velocities under study is 500-1590 m/s. Results of the group start of supercavitating strikers are given. [ABSTRACT FROM AUTHOR]

We consider the possibility of obtaining composites with increased mechanical strength resistant to high-velocity impact by means of self-propagating high-temperature synthesis (SHS) of metal-ceramic materials with graded composition-in particular, of layered type. A two-layer combined metal-ceramic material has been developed comprising NiTi-bonded titanium diboride (TiB2) layer on a metallic titanium substrate layer. The impact resistance of this composite is advantageous to that of a homogeneous titanium plate, which is manifested by the absence of a spall crater upon the impact of a spherical steel projectile and by stronger deformation and prefracture cracking of the projectile. [ABSTRACT FROM AUTHOR]

Water degassing and removal of salts by high-power acoustic pulses are analyzed. A model explaining the mechanisms of these processes is proposed. [ABSTRACT FROM AUTHOR]

Time-resolved measurements of the microwave field effect using optically detected EPR (ODEPR) have demonstrated that the amplitude and lifetime of the slow component of fluorescence are additionally reduced by an external microwave field, at a microwave frequency of 9400 MHz, a constant magnetic field of 0.3295 T and an oxalylfluoride pressure of 30 mTorr. This is accompanied by an increase in the fast component amplitude, at a constant decay rate of (2.36 x 0.19) 107 s-1. The fluorescence intensity was found to decrease, and phosphorescence intensity to increase, with subsequent saturation at higher microwave intensities. The experimental data are interpreted using the indirect mechanism theory in the limit of low-level density. [ABSTRACT FROM AUTHOR]

A photon echo induced exclusively by collisions of ytterbium atoms with buffer gas atoms has been observed at a 0 ⟷ 1-type1 S 0(6 s 2)-3 P 1(6 s6 p) 174Yb transition. The polarization properties of a collision echo and the buffer gas density dependence of its intensity agree with theoretical predictions of a model of depolarizing collisions that takes into account the dependence of a relaxation matrix on the velocity of active particles. Thus, direct experimental evidence of the relaxation anisotropy due to depolarizing collisions has been obtained. [ABSTRACT FROM AUTHOR]

The intermediate LIF spectra were observed and compared in the NO[sub 2] (λ[sub exc]>400 nm) and ClONO[sub 2] (λ[sub exc]=308 nm) photolyses. Both spectra could be assigned to the same transient. Transient fluorescence spectra were recorded in the 12 500-16 400 cm-1 range at λ[sub exc]=436.45 nm. Analysis shows that the observed intermediate spectra can be attributed to the NO[sub 3] radical. The NO[sub 3] lifetime variations in the presence of CF[sub 4], CF[sub 3]Cl, CF[sub 2]Cl[sub 2], CFCl[sub 3], and CCl[sub 4] were also studied. It was shown that these compounds only influence the photolysis yield of NO[sub 3], without affecting its lifetime. The magnetic field influence on the discrete and total NO[sub 2] fluorescence, and on the NO[sub 3] radical yield were also measured using λ[sub exc]=436.45, 458.13, 478.93, and 489.12 nm. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]