bluuebunny/crossref_metadata_2025_split huggingface dataset:
Segmented Penetrators
Authors: Weihrauch G. , Wollmann E. 
Published: May 2005

AbstractThis paper analyses the terminal ballistic performance of segmented rod penetrators in semi‐infinite, spaced as well as reactive targets. The model scaled projectiles with a mass of about 10 g are launched by a light gas gun of caliber 30 mm at velocities up to 4 km/s. To keep the initial acceleration low enough, the junction between the first and the second stage of the gun was appropriately modified. The projectiles are composed of a series of tungsten alloy segments guided by a thin light metal tube. Between the segments with a L/D‐ratio of one there are cylinders made of plastics or aluminium. Usually the space is in the order of one or two projectile diameters. The perforation power of such segmented rods is compared with two types of homogeneous projectiles of equal mass and velocity. One reference projectile has equal length but lower diameter, the other one has the same diameter but a lower length. Experiments against semi‐inifite targets show an increase in penetration depth of about 20 %, compared with homogeneous projectiles of the same diameter. This advantage vanishes if the reference projectile has equal length. In the four‐plate target as well as in the reactive armour, segmented rods are significantly less efficient due to their low stiffness and greater length.
Theoretical Analysis of the Penetration Performance of experimentally measured shaped charge jets
Authors: Heider N. 
Published: May 2005

AbstractThe cratering process of a shaped charge jet is a complex phenomenon because the jet consists of a series of discrete particles that create separate craters within the target. The cumulative effects taking into account the contribution of all jet particles give the final penetration performance. For a theoretical analysis of the terminal ballistic performance of shaped charge jets, it is therefore necessary to measure experimentally the complete three‐dimensional motion of each jet particle. This can only be done by sophisticated techniques like for example Double‐Orthogonal Synchro‐Streak (DOSST) introduced by Held. Data from such experiments can be used as input for penetration models to calculate the penetration depths of jets. The model used for this analysis includes a description of the crater shape together with an appropriate selection algorithm to find the impact position of a single jet particle within the already formed crater profiles. The calculated values for the penetration performance are compared with the data provided by DOSST experiments from Held.
Comparative characteristics of some experimental and computational methods for estimating Impact Sensitivity Parameters of Explosives
Authors: Afanas'Ev German T. , Pivina Tatyana S. , Sukhachev Dimitrii V. 
Published: May 2005

AbstractThis article presents some theoretical and experimental methods for estimating parameters of impact sensitivity. Possible relationships between the structures of compounds and the parameters characterizing the sensitivity of explosives to mechanical impact are analyzed.
Energy Output of Insensitive High Explosives by measuring the detonation products
Authors: Volk F. , Schedlbauer F. 
Published: May 2005

AbstractThe detonation products of high explosives are dependent on pressure and also on the confinement under which the detonation reaction proceeds. To determine the detonation products of less‐sensitive high explosives, such as TNT/nitroguanidine (NQ) and PBX charges with polybutadiene (PB) binder containing RDX together with or without aluminium (Al), experiments have been performed in a stainless steel chamber with a volume of 1.5 m3. These experiments were done under different ambient argon pressures up to 0.3 MPa. Gaseous reaction products were analysed by mass spectrometry and chemiluminescence analysis. Solid reaction products were analyzed measuring the carbon residue or the unreacted aluminium. It was found that the detonation products were highly dependent on the ambient pressure of argon. The most important changes of the reaction products and therefore also of the energy output were found between vacuum and atmospheric pressure of argon. With increasing pressure, H2 and CO decrease and CO2, H2O, Cs, NH3, HCN and CH4 increase together with the reaction enthalpy. By analysing the physical structure of the carbon residue, diamonds have been observed between 4 nm and 7 nm in diameter.
Considerations about the Analytical Modelling of Shaped Charges
Authors: Chanteret Pierre Yves 
Published: May 2005

AbstractThe problem of building and using analytical codes for shaped charge simulation is reviewed. The basic physics of the whole shaped charge functioning is considered, starting from explosive liner interaction, going through jet formation and jet break‐up, down to cratering into the target. For each stage of the phenomenon, a critical look is given to the existing analytical models, with the idea of determining which models are able to adequately predict the shaped charge behavior with keeping an as low as possible degree of complexity. On reviewing these analytical models, it is shown that some parameters have to be taken into account for a better understanding of what governs shaped charge performance.
Influence of Transverse Air or Inert‐Filled Gaps in HE Charges on the detonation velocity
Authors: Held Manfred 
Published: May 2005

AbstractGaps 0.8‐mm wide and transverse to the direction of detonation in high‐performance high explosive compositions, such as squeeze cast TNT/HMX (15/85) or pressed HMX/B (97/3), show no measurable time delay, or it must be less than 50 ns. As expected, delay times increase with the gap width. A surprising result, however, is the convex shape of the time delay curves, which begins at a gap width of about 1 mm. The delay time curves from air and plexiglass‐filled gaps resemble one another very much.
Electric Spark and ESD Sensitivity of Reactive Solids (primary or secondary explosive, propellant, pyrotechnics). Part II: Energy transfer mechanisms and comprehensive study on E50
Authors: Auzanneau Max , Roux Michel 
Published: May 2005

AbstractThe energy transfer mechanism from the electric spark to the reactive solid sample in powder form has been determined. Only a small portion of the solid is heated to the explosion critical temperature through a resistive heating by electric current. In fact, hot spots develop at the thinnest part of the solid, i.e. at intergrain contact points.We studied the evolution of thermal diffusivity and of sensitivity to electric spark as a function of powdered HMX granulometry. It allowed us to specify the respective importance of the grain size and shape in this evolution.
Simple Calculation Methods for Munitions Cookoff times and temperatures
Authors: Victor Andrew C. 
Published: May 2005

AbstractSimple one‐dimensional quasi‐static heat transfer calculations can be used to estimate fast cookoff times of cylindrical munitions with metal cases. The most critical parameter for the thermal analysis is the heat flux to the ordnance from the fire. One must remain aware that heating will be different for transparent flames of propane or methane test fires than they are for the opaque smoky flames of wood and jet‐fuel fires. Good values for material thermal conductivities and energetic material ignition behavior are also needed. Low‐conductivity composite cases cannot be analyzed in the same way because case mechanical failure is the primary initial failure path, rather than thermal conduction leading directly to ignition of the energetic material. Reaction violence cannot be calculated in a simple way with the present state of the art.Simple hand analysis of slow cookoff problems is limited to simple symmetric shapes of the type that were published over 30 years ago involving constant boundary temperatures. Modern computers, using finite‐difference codes can be used to readily solve problems with varying boundary temperatures to predict time to cookoff. However, as this paper shows, quasi‐static solutions of symmetric shapes (slabs, cylinders and spheres) can be obtained with desktop computer spreadsheets that give the same results as the finite‐difference codes. There are no a priori methods for predicting the violence of the slow cookoff reaction. These same comments apply as well to intermediate cookoff heating rates (greater than 3.3 K/h).Calculations by the methods of this paper place tools for designing experiments to explore cookoff behavior and for designing ordnance to meet insensitive munitions requirements on virtually every desktop.
Characterization of the Zirconium/Potassium Perchlorate/Nitrocellulose pyrotechnic system by simultaneous thermogravimetry‐differential thermal analysis‐mass spectrometry
Authors: Berger B. , Charsley E. L. , Warrington S. B. 
Published: May 2005

AbstractSimultaneous thermogravimetry‐differential thermal analysis‐mass spectrometry have been used to characterize the zirconium/potassium perchlorate/nitrocellulose pyrotechnic system, by examining the components and their binary and ternary combinations under inert atmosphere conditions. Zirconium and potassium perchlorate were found to give an exothermic solid state reaction between 300°C and 500°C and the reaction was influenced significantly by the presence of small amounts of nitrocellulose. The decomposition of unreacted potassium perchlorate was observed to commence in the latter stages of the reaction and was found to be catalyzed by presence of the reaction products ZrO2 and KCl.
Reactions of TATB‐Based Explosive with Molten Metal
Authors: Maienschein Jon L. , Nichols Albert L. , Wardell Jeffrey F. 
Published: May 2005

AbstractThe reactions of combustion products (CO, H2O) from the insensitive high explosive LX‐17 (92.5 wt% 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB), 7.5 wt% Kel‐F 800 binder) with molten metal (75 a%Nd, 25 a% Fe) were studied, to determine their contribution to the energy release rate of deflagrating LX‐17, Kinetic data taken with gas mixtures of CO and H2O, and larger‐scale tests with LX‐17, showed that the reactions were slow and incomplete and that there was no significant contribution to the energy release rate. From the tests with JX‐17, the effective flame temperature and burn velocity were dependent on confinement of gas products. LX‐17 preheated to 500 K ‐ 510 K showed effective flame temperatures of 1100 K ‐ 1400 K and burn rates of 0.08–0.11 mm/s, depending on the extent of gas confinement by the molten metal.
Thermal Decomposition of BAMO Copolymers
Authors: Kimura Eishu , Oyumi Yoshio 
Published: May 2005

AbstractThe effects of copolymerization of THF, as an inert component, AMMO, as an energetic one and NMMO, as a nitrate ester, with BAMO on their thermal decomposition are reported here. Although the thermal decomposition of the BAMO and NMMO units in B/N(7/3) carry out independently and the heat generated by the NMMO unit decomposition accelerates the BAMO unit decomposition, the THF and AMMO units do not affect that of the BAMO unit in B/T(7/3) and B/A(7/3). One exothermic peak in DSC is shown for B/A(7/3) and B/T(7/3) except for B/N(7/3) which shows two peaks. One peak at lower temperature is from the NMMO unit decomposition and the other is from the BAMO unit. The rate of decomposition of B/A(7/3) is the same as that of poly(BAMO), which indicates that the reactivity of the AMMO unit is equal to that of the BAMO unit.In propellant, containing 75% HMX and 25% copolymer binder, burning rate of B/A(7/3)/HMX is faster than that of B/N(7/3)/HMX. Although the heat of decomposition for B/A(7/3) in DSC is smaller than that for B/N(7/3), that of B/A(7/3)/HMX is larger than that of B/N(7/3)/HMX. The reaction occurred in the condensed phase of the propellant, therefore, may play an important role in the combustion.
Numerical calibration of donor systems for some GAP tests
Authors: Hudson Lewis C. , Bernecker Richard R. 
Published: May 2005

AbstractNumerical models of various donor/attenuator systems utilized in gap tests were evaluated with the DYNA2D hydrocode. Three donor (pressed pentolite)/attenuator (PMMA) configurations were tested. Case I and Case 2 had a pentolite donor which was 2 cm × 2 cm right cylinder; the cell size was smaller in Case 1. Case 3 utilized a composite pentolite donor 2.07 cm long but having stepped diameters of one and two cm; the cell size was quite similar to that of Case 2. Peak (axial) pressure versus distance results from Case 1 were scaled and Compared to experimental data for both the NOL large scale gap test (LSGT) and the NSWC expanded large scale gap test (ELSGT). The comparison was found to be very good for the LSGT but less satisfactory for the ELSGT. Peak (axial) pressure versus distance results from Case 1 were the also compared to Case 2, a coarser zoned model similar to Case 1, and Case 3. This comparison showed that the composite donor produced peak (axial) pressures similar to those from the LSGT model. Normalized peak pressure versus radial distance and shock profiles were compared for the three cases and found to be quite similar. Additional normalized peak pressure versus radial distance and normalized pressure versus time information from Case 1 is plotted to show how the pentolite/PMMA rarefaction affects both the axial and radial pressure‐time histories.
Gun Propulsion Concepts. Part II: Solid and Liquid Propellants
Authors: Maag H.‐J. , Klingenberg Günter 
Published: May 2005

AbstractThe present paper deals with both the conventional solid propellant and modern liquid propellant gun concepts. Solid propellant guns, known since the 14th century, are still being investigated, although this concept represents a relative mature technology. Thus any progress is predominantly a refinement of existing techniques. Comparatively, liquid propellant gun research and development address a rather new technique and invoke some improvements over conventional solid propellant systems. Especially, automatic system are easier to design, artillery zoning is more easily achieved, cartridge disposal is avoided, and high‐energetic liquid propellants or special system designs offer higher performance. Therefore, the liquid propellant gun technology seems to be a near‐term technology that, complementary to solid propellant gun concepts, might play a role in future armament.
Analysis of 3‐Nitro‐1,2,4‐Triazole‐5‐One (NTO) in Explosive Mixtures by capillary electrophoresis
Authors: Oehrle Stuart A. 
Published: May 2005

AbstractRecently a new explosive, 3‐Nitro‐1,2,4‐triazole‐5‐one (NTO) has attracted interest as possible replacements for or inclusion in various military propellants and explosives. Analysis of NTO compounds as well as 14 other nitramine and nitroaromatic explosives could be accomplished by capillary electrophoresis using a technique known as MECC, micellar electrokinetic capillary chromatography. A borate/boric acid buffer with sodium dodecylsulfate (SDS) was used in conjunction with direct UV detection at 185 nm.
Thermal Decomposition of Energetic Materials 69. Analysis of the kinetics of nitrocellulose at 50 °C–500 °C
Authors: Brill T. B. , Gongwer P. E. 
Published: May 2005

AbstractKinetic constants for decomposition of nitrocellulose in the 50 °C to 500°C range are analyzed. At T < 100°C, three processes (depolymerization, peroxide formation, and hydrolysis) are consistent with the reported kinetics. For T = 100°C–200°C, 28 of 30 previously reported kinetic measurements can be organized clearly into two categories by the use of the kinetic compensation effect. These two groups fit the first‐order and autocatalytic processes. Conflicting interpretations are reconciled by this approach. At T > 200°C, the kinetics are consistent with the existence of the first‐order step and desorption of the products as two parallel processes which, together, control the rate. Time‐to‐exotherm and mass burning rate kinetics are compared as temperature‐dependent reaction‐desorption events.
Thermal Degradation of the Binder in GAP‐Based Propellants
Authors: Perreault François , Benchabane Mahmed 
Published: May 2005

AbstractThe long‐term stability of the binder in GAP‐based propellants is investigated in this study. Thermal degradation of the polymer network, being related to the extractable proportion of GAP, is quantified by means of Fourier transform infrared (FTIR) spectroscopy while the degradation products are analysed by size exclusion chromatography (SEC). Our results concerning the aging of four different formulations at 80°C demonstrate the necessity to add a stabilizer like diphenylamine (DPA) to the propellants. Other additives like MgO and TEPANOL are also shown to have a significative stabilizing effect.
Separation of NTO Related 1,2,4‐Triazole‐3‐One Derivatives by a high performance liquid chromatography and capillary electrophoresis
Authors: Le Campion L. , Adeline M. T. , Ouazzani J. 
Published: May 2005

AbstractThis report describes a direct, rapid and sensitive method for separating and quantifying 5‐nitro‐1,2,4‐triazole‐3‐one 1 (NTO) and 5‐amino‐1,2,4‐triazole‐3‐one 2. Analyses were performed on water and on soil containing compounds 1 and/or 2, using reversed phase HPLC columns. A mixture of compounds 1, 2, Urazole 3 and 1,2,4‐triazole‐3‐one 4 was well separated by HPLC on a Hypercarb column packed with porous graphitic carbon, or by capillary electrophoresis. Both methods could be used to detect such compounds in the environment and monitor their biological and chemical degradation.
Modelisation of combustion equilibria with Monte‐Carlo numerical method
Authors: Brunet L. , Forichon‐Chaumet N. , Lombard J. M. , Espagnacq A. 
Published: May 2005

AbstractThe computation of complex combustions is made classically by using an iterative Newton‐Raphson method, applied to the resolution of a system of equations under constraint by the method of Lagrange multipliers. In many mineral combustions, there are products of reaction that present the same formula but belong to different phases (solids, liquids or gaseous). In these cases, the classic method ends frequently in singular matrix. Indeed, combustion equations can present in these cases, several equal or very close solutions, which induce a numerical fork phenomenon (“stiff” problems) and a chaotic algorithm behaviour. The method presented uses a Monte‐Carlo random algorithm: the Method of Random mass Statements. It presents the advantage of converging in numerically stiff cases. It furthermore provides results equal to the classic method for non‐stiff problems.
HPLC optimization of the separation of explosives and propellant components with an octadecyl phase by computer simulation
Authors: Kaiser Manfred 
Published: May 2005

AbstractHigh performance liquid chromatography (HPLC) is used in a large extent for environmental analysis. In this field many components have to be determined at the same time, but it is difficult to find the optimum separation conditions. Therefore, retention times of explosives and propellant components were determined at different solvent compositions of methanol/water and different temperatures on a column with an octadecyl phase. From the data constants were calculated for solvent and temperature dependence. With the determined data different column conditions were simulated by computer and the separation was optimized. The optimal separation was verified experimentally and compared with the calculated values. The deviation from calculated and experimental retention times lies as a rule below 2% and has a maximum of approximately 3.3%. Thus, separation of substance mixtures can be optimized by determination of column constants for temperature and solvent dependence.
Numerical Modeling of Underwater Explosion Properties for an aluminized explosive
Authors: Lee Jaimin , Kuk Jeong‐Hyun , Cho Yong‐Soo , Song So‐young , Lee Jun‐Wung 
Published: May 2005

AbstractUnderwater explosion properties of an aluminized explosive, DXD‐03, were numerically modeled by two burn techniques; a programmed‐burn technique and a rate equation calibrated from two‐dimensional steady‐state detonation experiments based on the detonation shock dynamics. The modeling by using the programmed‐burn technique did not reproduce experimental data well; 12% to 34% error in peak pressure and 20% error in bubble period. The modeling by using the rate equation reproduced the experimental observations very well. Although there was some difference in peak pressure, the shock profile agreed very well with experimental observation. The calculated bubble period agreed with the experimental data within 1%. This result demonstrates that the underwater explosion properties for aluminized explosives can be calculated only when the slow energy release of aluminium is modeled properly.
Energetics of charge–charge interactions in proteins
Authors: Gilson Michael K. , Honig Barry H. 
Published: May 2005

AbstractElectrostatic interactions between pairs of atoms in proteins are calculated with a model based on the linearized Poisson‐Boltzmann equation. The equation is solved accurately by a method that takes into account the detailed shape of the protein. This paper presents applications to several systems. Experimental data for the interaction of ionized residues with an active site histidine in subtilisin BPN' allow the model to be tested, using various assumptions for the electrical properties of the protein and solvent. The electrostatic stabilization of the active site thiolate or rhodanese is analyzed, with attention to the influence of α‐helices. Finally, relationships between electrostatic potential and charge‐charge distance are reported for large and small globular proteins. The above results are compared with those of simpler electrostatic models, including Coulomb's law with both a distance‐dependent dielectric constant (ϵ = R) and a fixed dielectric constant (ϵ = 2), and Tanford‐Kirkwood theory. The primary conclusions are as follows: (1) The Poisson‐Boltzmann model agrees with the subtilisin data over a range of ionic strengths; (2) two α‐helices generate a large potential in the active site of rhodanese; (3) ϵ = R overestimates weak electrostatic interactions but yields relatively good results for strong ones; (4) Tanford‐Kirkwood theory is a useful approximation to detailed solutions of the linearized Poisson‐Boltzmann equation in globular proteins; and (5) the modified Tanford‐Kirkwood theory overscreens the measured electrostatic interactions in subtilisin.
Protein stability and electrostatic interactions between solvent exposed charged side chains
Authors: Akke Mikael , Forsén Sture 
Published: May 2005

AbstractTo investigate the contribution to protein stability of electrostatic interactions between charged surface residues, we have studied the effect of substituting three negatively charged solvent exposed residues with their side‐chain amide analogs in bovine calbindin D9k—a small (Mr 8,500) globular protein of the calmodulin superfamily. The free energy of urea‐induced unfolding for the wildtype and seven mutant proteins has been measured. The mutant proteins have increased stability towards unfolding relative to the wildtype. The experimental results correlate reasonably well with theoretically calculated relative free energies of unfolding and show that electrostatic interactions between charges on the surface of a protein can have significant effects on protein stability.
Crystallographic refinement of human serum retinol binding protein at 2Å resolution
Authors: Cowan Sandra W. , Newcomer Marcia E. , Jones T. Alwyn 
Published: May 2005

AbstractHuman serum retinol binding protein (RBP) in complex with retinol has been crystallographically refined to an R‐factor of 18.1% with 2Å resolution data. The protein topology results in an anti‐parallel β‐barrel that encapsulates the retinol ligand. A detailed description of the protein and the binding site is provided. Our structural work has helped to define a family of proteins, many of which are carrier proteins for smaller ligand molecules. We describe the structural basis for the conservation of sequence within the family.