bluuebunny/crossref_metadata_2025_split huggingface dataset:
Barium Sulfate Precipitation: Crystallization kinetics and the role of the additive PMA‐PVS
Authors: van Drunen Michiel A. , Merkus Henk G. , Scarlett Brian , van Rosmalen Gerda M. 
Published: December 2004

AbstractThe precipitation of barium sulfate was investigated by photon correlation spectroscopic (PCS) measurements of the growing crystals combined with electrical conductivity measurements of the mother solution. Small silica seeds (36nm) were added to the solution. Therefore, heterogeneous nucleation did not take place on the walls and on the stirrer, which is usually the case, but on the seeds. Hence the growth of the crystals which had nucleated on the seeds could be studied by PCS. In order to avoid the ill‐conditioned inversion of the measured raw data, the autocorrelation functions, a population balance model was used to calculate these functions with the help of a kinetic model taken from the literature. The measured an the calculated autocorrelation functions could coincide and adjustable parameters were found from a least‐squares fit. The measurements revealed that nucleation is strongly enhanced by PMA‐PVS (polymaleic acid–polyvinylsulfonic acid). However, a simple model which assumes langmuir adsorption of PMA‐PVS on the crystal surface did not describe the kinetics very well. The nucleation rate in the absence of the additive was found to be J=1.3·1010 exp(−27/In2S) [m−3s−1], while the growth rate was G=2.6·10−8(S−1)2/3 S1/3 exp(−29/3 In S) [ms−1]. These results match results taken from the literature fairly well.
Sizing of Irregular Particles Using a Phase Doppler System
Authors: Naqwi Amir A. 
Published: December 2004

AbstractResponse of a phase Doppler system to irregularly shaped particles is examined and shown to deviate qualitatively as well as quantitatively from the spherical particles. Nevertheless, the measured phase distributions based on an ensemble of particles exhibit a high degree of order and simplicity. The experimental data and the stochastic modeling of the process have shown that the phase Doppler technique can be used successfully for in‐situ sizing and velocimetry of irregular particles. In the case of irregular crystalline particles, mean size and standard deviation can be deduced without requiring any assumptions regarding the functional form of the size distribution. As opposed to other optical techniques, phase Doppler can be used, in principle, near the backscattering location, so that a single optical window would be employed for transmission of laser light and collection of the scattered signals. Furthermore, size measurements can be velocity‐resolved, i.e. a size distribution can be associated with each bin of the velocity histogram.
Modeling of a Rotary Drum Granulator for Control
Authors: Reddy Bathala C. , Murthy Dodlaty V. S. , Rao Chamarti D. P. 
Published: December 2004

AbstractA phenomenological model with 12 parameters for rotary drum granulation with the help of material balance equations taking into account the growth and death functions was developed. Experiments were conducted and the data were used to obtain model parameters with reference to the operating conditions and for validation of the model. It was concluded that the proposed model is adequate for the representation of dynamics and hence this model can be recommended for dynamic simulation leading to improved control of granulation circuits.
Detonation Velocity of PETN in Small confined cylindrical charges
Authors: Dinegar R. H. 
Published: December 2004

AbstractSteady state detonation velocities have been measured in small brass‐confined pressings of PETN. These velocities were found to vary linearly with the reciprocal of the charge diameter and directly with the compact density. For a pressing density of 950 kg/m3 the velocity at infinite diameter was calculated to be 5.27 km/s (50.02 kmk) and the Eyring‐type „reaction‐zone length”︁ 0.54 mm (±0.02 mm).
Detonability of Slurry Blasting Agents
Authors: Michot C. , Bigourd J. 
Published: December 2004

AbstractThe detonability of slurry blasting agents is characterized by their critical detonation diameter and their cap sensitivity. A quick method using conical charges permits the critical detonation diameter to be measured.The influence of density on the detonability was examined. Density of the slurry was varied by gassing before shotfiring or by compressing the slurry on firing. The results are different according as the slurry contains an explosive or non‐explosive sensitizer.
Growth of 1,3,5‐Triamino‐2,4,6‐trinitrobenzene (TATB) I. Anisotropic thermal expansion
Authors: Kolb John R. , Rizzo H. F. 
Published: December 2004

AbstractExpansion of TATB is studied on a molecular level by means of x‐ray crystallography. Continuous monitoring of the cell constants of TATB between 214 K and 377 K allows calculation of a volume change of +5.1% for this molecular system. Expansion of the pure material is almost exclusively a function of a 4% linear increase in the c axis (the perpendicular distance between sheets of hydrogen‐bonded TATB). Calculated from these data, the volume coefficient of thermal expansion for crystalline TATB is 30.4 × 10−5 K−1. The structural features of crystalline TATB and its anisotropic thermal‐expansion behaviour are compared with those of graphite and boron nitride. Two other crystalline products in the bulk TATB are either actual polymorphs of TATB or impurities.
Réflexions sur la sensibilité des explosifs polynitrés aromatiques
Authors: Brassy C. , Roux M. , Auzanneau M. 
Published: December 2004

AbstractDes publications récentes sur la sensibilité à l'impact et la sensibilité thermique des explosifs polynitrés aromatiques sont commentées.En sensibilité à I'impact, Kamlet et Adolph ont remarqué l'existence de deux familles d'explosifs pour lesquelles h 50% est une fonction linéaire du bilan en oxygène OB100. Ces deux corrélations peuvent se ramener à une seule si dans le calcul du bilan en oxygéne on ne tient pas compte des CH en a des groups NO2. Pour les groupements attachés au cycle benzénique , on peut calculer des incréments de sensibilité.En sensibilité thermique, les résultats de Zeman et ceux d'Hutchinson, Krishna Mohan et Millar peuvent être interprétés. L'knergie EA d'activation de décomposition thermique est une fonction linéare de log A, logarithme du facteur préexponentiel. En conséquence, ΔH* I'enthalpie d'activation est proportionelle à log A, ΔH* est proportionelle à ΔS* l'entropie d'activation, ΔH* est proportionelle, pour les tétryls, à ΔG l'enthalpie libre d'activation calculke pour la moyenne harmonique des températures.Il serait intéressant de donner une signification physique au bilan en oxygène défini par Kamlet et Adolph, à relation enthalphie‐entro‐ pie et à la relation enthalpie‐enthalpie libre.
On the use of Redundant Pyrotechnic Delays
Authors: Yaniv A. 
Published: December 2004

AbstractThe performance of redundant pyrotechnic delays is analyzed. It is found that the average delay time of a redundant cluster of delays is shorter than the corresponding average of the individual delays. Also, the standard deviation of the cluster delay time is smaller than the corresponding individual delay standard deviation. These two effects are found to be monotonic functions of the number of delays in the cluster. The effect of the delay reliability on the cluster statistics is shown to be qualitatively similar to a reduction in the effective cluster size.
Capacitor‐Discharge Initiation of a Detonator containing a vacuum‐deposited thin‐film chromium bridge
Authors: Austing James L. , Tulis Allen J. , Hrdina Donald J. , Joyce Richard P. , Urbanski Edward , Fyfe Donald W. , Smith Robert D. , Letendre Guy 
Published: December 2004

AbstractAn experimental program is described in which the capacitor‐discharge initiation characteristics of a detonator containing a vacuum‐deposited thin‐film chromium bridge were studied. The objective of the effort was to define the conditions that would result in overall function times of 10 μs or less. The threshold initiation energy of the detonator was in the range of 11.5 mJ–20.0 mJ. Consistent performance was obtained from a firing energy of 54 mJ, which was achieved by a 5‐μF capacitor charged to 147 V. Under these conditions, the average overall function time was 4.2 μs, with a standard deviation of 0.2 μs. Other tests showed that at higher capacitances and lower voltages the function time increased substantially and became more nonreproducible, even though the stored energy was considerably above the threshold value.
Fragment Generator
Authors: Held M. 
Published: December 2004

AbstractThe design of a fragment generator and the determination of the hit density and of the velocity distribution are described in detail.From the correlation of the fragment hits on the target plate and the X‐ray flash radiographs it is possible to ascertain the launch angles in the elevation and azimuth directions and, hence, also to determine the true distances the fragments have traveled from the point of detonation of the high explosive charge to the location where the radiograph was taken. In this manner, a precise determination of the velocities of the individual fragments can be made.In spite of the rather large scatter of the depths of penetration of the cube‐shaped fragments in the mild‐steel target plate, a correlation can be established between the impact velocity and the depth of penetration.
Manufacturing of Multiclads Using a Single Explosive Charge
Authors: Shoukry S. N. , Hegazy A. A. 
Published: December 2004

AbstractA technique for the fabrication of several mono and/or bimetallic cladded plates using a single explosive charge has been developed at our laboratories. This technique enables the explosive welding of thin plates or foils which are otherwise produced by the rolling of thick explosively cladded plates. This paper describes the technique and lays down the theoretical basis for the determination of the process parameters. It is shown that up to four sheets of 0.5 mm thick stainless steel cladded to 2.0 mm mild steel could be produced using a single explosive charge. The technique was also used for the manufacturing of 8 sheets of 0.25 mm copper foil cladded to 0.5 mm mild steel plate.
High‐performance liquid chromatographic separation of diphenylamine and its reaction products with nitrogen oxides
Authors: De Jong A. L. , Verweij A. 
Published: December 2004

AbstractReversed phase high‐performance liquid chromatography (HPLC), using a mobile phase composed of acetonitrile, methanol and water is preferably applied to separate diphenylamine and its major reaction products with nitrogen oxides. This paper describes the evaluation of the preferred chromatographic systems and the application of HPLC to analyse single base propellants.
Investigation of the decomposition processes in double‐base propellants and nitrocellulose under vacuum and oxygen
Authors: Kučera V. , Havránková E. 
Published: December 2004

AbstractThere is described the application of an automated vacuum stability test in following the decomposition and stability of double‐base propellants and nitrocellulose. There is also described a manometric stability test of propellants based on the decomposition in oxygen. This method makes possible to determine small differences of chemical stability and to substitute the time consuming methods based on HPLC.
Corner‐Turning Distance and Retonation Radius
Authors: Held Manfred 
Published: December 2004

AbstractAll high explosives, at least the ones used in military applications, have a specific minimum detonation radius, Rmin with which the detonation can change its direction through 90° or 180°. It is to be emphasized that this applies not only to thc so‐called insensitive high explosives, but the sensitive explosives of course have smaller radii than the insensitive ones.The corner‐turning distance, As, determined in the radial test, also corresponds to the minimum radius, Rmin for the detonation wave to invert its direction through 180°. The radial test is a simple method, with regard to both design and analysis, that is suitable for determining the 90°‐distance, or the minimum detonation radius, Rmin.
Modeling shock initiation and detonation divergence tests on TATB‐Based Explosives
Authors: Tarver Craig M. 
Published: December 2004

AbstractThe Pantex shock initation gap test, the Pantex corner turning test for detonation divergence, and recent short shock pulse shock initiation experiments using embedded gauges on TATB‐based solid high explosives are calculated in the two‐dimensional hydrodynamic computer code DYNA2D using the published ignition and growth reactive flow model for LX‐17. The calculations demonstrate that the Pantex gap test, like all gap tests for shock initiation, produces a complex two‐dimensional flow field involving a curved leading shock front and rarefaction waves form the rear and from the edge of the explosive being tested. The predicted brass gap thickness of 2.375 ± 0.125 mm for LX‐17 agrees closely with the measured critical gap thickness of 2.23 mm for 50% detonation. Excellent calculational agreement is also obtained with measured rates of detonation wave divergence for LX‐17 in the Pantex corner turning test. The reaction rates for TATB‐based explosives are varied to demonstrate the extreme sensitivity of this test to changes in explosive properties. Recent embedded particle velocity gauge experiments using various thickness flying plates of magnesium impacting PBX‐9502 are accurately calculated using the standard LX‐17 reaction rates.
Similarities of Shock Wave Damage in Air and in Water
Authors: Held Manfred 
Published: December 2004

AbstractThe damage done to structures in air or under water by a charge of mass W exploding a certain distance R away, can in both media be described by the so‐called square root relation, \documentclass{article}\pagestyle{empty}\begin{document}${\rm R} \approx \sqrt {\rm W}$\end{document}. This is better than a simple rule‐of‐thumb, because it implies the physical quantity of an energy density. It is shown that this energy density can also be derived from the product of peak overpressure times impulse for a blast wave in air or a shock wave in water.
Do Not Convert Emulsions into Dynamites
Authors: Ekman Gunnar 
Published: December 2004

AbstractThe emulsion explosives have many advantages compared to dynamites from the safety point of view. However, there is a tendency to develop cartridged emulsions to be more and more dynamite‐like. According to our opinion this are steps in the wrong direction. It must be better to develop blasting methods, that are adjusted to the properties of the emulsions.
Fragmentation of Cast Iron Blocks by a Confined Explosive Charge: A new performance evaluation test for commercial explosives
Authors: Rao P. S. , Mohan V. Krishna , Bhasu V. C. Jyothi , Kumar A. S. 
Published: December 2004

AbstractThis paper describes a new method to assess the performance of small diameter explosives under laboratory conditions. While conventional strength tests often do not correctly reflect the performance characteristics of such explosives, model tests using rocks are not convenient due to constraints imposed by the size of the test block. Cast iron being a brittle material, fractures like rock and also its mechanical properties make it a suitable material for simulating rock under laboratory conditions. Tests have been carried out with different explosives in a cylindrical block of cast iron having a 27‐mm diameter central hole of a certain depth. Mean fragment size (X50) has been used as the criterion to rank different explosives with respect to their strength. Using fracture surface energy of cast iron and detonation properties of the explosives tested, the maximum fragment size could be predicted on the basis of an energy balance model. The predicted maximum fragment sizes are in fair agreement with the experimentally obtained ones. While the limitations of the proposed test are pointed out, it appears that cast iron block fragmentation could serve as an useful technique for evaluating the strength of commercial explosives.
Burning Rate Augmentation of BAMO Based Propellants
Authors: Oyumi Yoshio , Inokami Kiyotaka , Yamazaki Kazuhiro , Matsumoto Koki 
Published: December 2004

AbstractThermal decomposition and the burning properties of BAMO based propellants with HMX or AN/HMX have been investigated. The heat generated by the azide binder decomposition initiated and accelerated the thermal decomposition of HMX and AN. Ammonium perchlorate (AP) and lead stearate with carbon black significantly altered the mechanisms of the thermal decomposition and the burning properties of the HMX based propellants. AP showed an increase in burning rate with a slight decrease in burning rate pressure exponent. The lead catalyst yielded high value of the burning rate with the lowest pressure exponent. The ammonium dichromate also influenced the mechanisms of the thermal decomposition and the burning properties of the AN/HMX samples. The combination of ammonium dichromate and copper chromite was the most effective on the burning rate augmentation of AN/HMX based propellants. AN sublimed and evaporated from the condensed phase and mainly reacted exothermically in the gas phase HMX and AN/HMX based propellants showed smokeless burning characteristics in the small rocket motor combustion tests.
Characterization of plastic‐bonded explosives by pyrolysis gas chromatography and multivariate data analysis. Part I: Setup of the method
Authors: Rietjens M. , Wils E. R. J. 
Published: December 2004

AbstractA further development of the procedure based on pyrolysis gas chromatography (Py‐GC) for the characterization of plastic‐bonded explosives (PBX's) is described. After grinding, the PBX samples were pressed on a pyrolysis wire followed by Py‐GC analysis. The peak areas obtained were normalized and subsequently submitted to multivariate data analysis. The use of principal component analysis (PCA) was tested on five samples which differed slightly in composition and age. The results were promising and showed that PCA is a powerful tool for the differentiation between PBX samples. The pyrolysis conditions were examined and optimized. A dependency was found between the sample loading (mass) and the position of the samples in a PCA score plot and indicates that control of the sample loading is important in obtaining reproducible results. For PBX samples an optimum pyrolysis temperature was determined around 540°C, close to the previous selected pyrolysis temperature of 610°C. In examining the pyrolysis at lower temperatures it was found that RDX or HMX is pyrolyzed independently from the binder. It appeared that PBX samples were inhomogeneous despite a thorough mixing of the constituents during preparation.
Thermomechanical Properties of Rocket Propellants and Correlation with cookoff behaviour
Authors: Ho S. Y. 
Published: December 2004

AbstractThe cookoff behaviour of several plasticized HTPB/AP and HTPB/RDX propellants has been evaluated using the standard Small‐Scale Cookoff Bomb (based on the NWC design) and a modified version of the standard equipment (whereby the reaction violence can be measured quantitatively) to investigate the effects of (1) plasticizer level on the thermomechanical properties and its role in moderating the cookoff response, and (2) heating rate. A change from slow to fast cookoff behaviour was observed for the plasticized HTPB/RDX propellants; the measured pressures/energy output at the slow heating rate were much lower than those at the fast heating rate for the same propellants. The thermal distribution/gradient at various positions and depths in the cylindrical propellant specimen, during fast and slow cookoff, were measured in order to understand the reversal in the severity of the response shown by the plasticized RDX propellants when the heating rate was changed. Thermomechanical properties of the propellants were measured and correlated with cookoff behaviour, to provide further insight into the cookoff mechanisms.
Effects of Copolymerization Ratio of BAMO/NMMO and catalyst on sensitivity and burning rate of HMX propellant
Authors: Kimura Eishu , Oyumi Yoshio 
Published: December 2004

AbstractThree different copolymerization ratios of BAMO/NMMO copolymers were studied for the requirement of not only a high specific impulse but also an insensitive munition characteristics for HMX composite propellant. These molar ratios of BAMO/NMMO were 8/2, 7/3, 6/4. Although the heat of DSC measured was relatively largest in B/N(7/3) propellant, there was no difference in the thermal decomposition characteristics. The exothermic reactions of azide binder and of HMX occurred in the same temperature region. The faster burning rate was obtained by the more BAMO ratio in the binder. The shock sensitivity was the lowest in B/N(7/3) HMX composite propellant. This unexpected stability might be caused by the physical effect of the molecular structure of B/N(7/3) which might contribute to the sudden dumping of the impact shock. Although the detonation velocity, because faster as BAMO ratio, increased like as the burning rate, the detonation pressure was the lowest in B/N(7/3) propellant. The mixture of catocene and copper chromite augmented the burning rate 1.6 times with decreasing temperature sensitivity.
The Interaction between Otto Fuel II and Aqueous Hydroxylammonium Perchlorate (HAP), Part II: Gas Evolution and Changes in HAP Solution Acidity
Authors: Bellerby John M. , Blackman Christopher S. 
Published: December 2004

AbstractHeadspace gas analysis has shown that nitrous oxide (N2O) is the principal gas evolved during contact between small volumes of Otto Fuel II (OF) and 82% aqueous hydroxylammonium perchlorate (HAP) at temperatures close to ambient. The gas is produced mainly from the 82% HAP layer and is generated in significant amounts only after the OF has become blackened as a result of extreme degradation. The pH of the HAP solution falls during contact with OF and the OF blackening point is the same for each of three storage temperatures investigated, suggesting that the production of N2O may depend upon the attainment of a specific HAP solution acidity. It is suggested that the propyleneglycol dinitrate (PGDN) component in OF undergoes acid hydrolysis at the liquid/liquid interface and that the nitric acid produced leads to the decrease in HAP solution pH and to stabilizer depletion in OF. Experiments involving contact between 82% HAP and the other components of OF confirm the key role of PGDN: in its absence there is no change in HAP solution acidity, no gas evolution and no violent reaction between the two liquids.