bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of relaxation time spectra by analytical inversion using a linear viscoelastic model with fractional derivatives
Authors: Friedrich Chr. , Braun H. , Weese J. 
Published: December 2004

AbstractRecently, Friedrich proposed an empirical model for linear viscoelastic fluids corresponding to a constitutive equation with fractional derivatives [Phil. Mag. Lett., 66, 287 (1992)]. For this model, the relaxation modulus, the dynamic moduli, the relaxation time spectrum, and other material functions have been explicitly calculated as a function of the few parameters that characterize a viscoelastic fluid within this model. By fitting this model to experimental data, the model parameters can be determined and other material functions, in particular the relaxation time spectrum, can be calculated immediately. This paper reports to what extent this method, which may be called analytical inversion, is appropriate for the determination of relaxation time spectra. For that pupose, the spectra of a number of very different polymeric materials are determined with this method. The spectra calculated in this way are compared with the spectra obtained by nonlinear regularization. It turns out that the empirical model describes the linear viscoelastic properties of a variety of different materials with high accuracy. Keeping in mind that the determination of the relaxation time spectrum requires the solution of an ill‐posed problem, the agreement between the relaxation time spectra obtained by analytical inversion and by regularization is satisfactory for these materials.
An algorithm for analysis of polymer filling of molds
Authors: Voller V. R. , Peng S. 
Published: December 2004

AbstractA numerical implementation of the Volume of Fluid (VOF) free surface technique, applied to a filling process governed by a potential flow, is introduced. The implementation is based on a finite element control volume space discretization and uses an implicit time integration. This allows for the accurate tracking of the filling front using large simulation time steps in molds with complex geometries. The approach is validated on comparision with the analytical solution for filling a one‐dimensional tube and with two‐dimensional results obtained with previously‐presented filling algorithms. Examples of the application of the approach in the analysis of structural resin transfer molding (SRTM) are presented. The capability of the method is demonstrated on predicting “race tracking” and “dry spotting” phenomena. The CPU requirement for a typical analysis is on the order of 1 to 20 s on pesonal computers.
Performance of reprocessed multilayer LDPE/nylon‐6 film
Authors: Nir M. M. , Ram A. , Miltz J. 
Published: December 2004

AbstractMultilayer LDPE/nylon‐6 films with an overall content of 71 wt% LDPE, 24 wt% nylon‐6, and 5 wt% PE‐based tie‐layer adhesive were reprocessed under both minimal and extensive mixing conditions. Thermal and mechanical properties, oxygen and water vapor permeability, and morphology of the reprocessed samples were determined. The modulus and yield stress of the reprocessed films fell between those of the pure homopolymers, whereas percent elongation at break and energy‐to‐break for all reprocessed films were less than those of the homopolymers. In minimally reprocessed film, layering of LDPE (low‐density polyethylene) and nylon‐6 was retained, whereas in extensively mixed samples, nylon‐6 domains were spherical and ranged from 0.2 to 7 μm. Minimally reprocessed film exhibited good O2 and H2O vapor barrier properties, whereas extensively‐mixed samples had poor barrier properties. Properties of well‐mixed blends prepared both with and without adhesive showed that 5 wt% adhesive did not compatibilize the LDPE and nylon‐6 components.
Quick Optical Measurement of Particle Distribution in a Sedimentation Apparatus
Authors: Staudinger Gernot , Hangl Manfred , Pechtl Peter 
Published: December 2004

AbstractThe determination of the particle size distribution of a powder may last up to 14 hours with standard sedimentation techniques such as an Andreasen pipette.If, in a photosedimentometer, not only the one sensor close to the bottom is incorporated but a number of sensors positioned at different heights, the time required for determining the particle size distribution of a powder may be reduced to 15 minutes. For each sensor there is an optimum location, which is determined both by the distance from the surface to the lowest and the highest sensor and by the number of sensors.The instrument, equipped with three measuring sensors and a reference sensor is connected to a personal computer. The measured particle size distributions are reproducable with a standard deviation of less than 2%. Agreement with a Sedigraph or a sedimentation balance is about the same as the agreement of these two instruments with each other.The time required for the determination of a particle size distribution of a quartz powder suspended in water with particle diameters from 1.5 to 60 μ is 15 minutes.
Fractal Differentiation Between Wear and Contaminant Particles found in mining machinery lubrication systems
Authors: Hancock David J. , Richards Michael J. , Adler Jeremy 
Published: December 2004

AbstractThis paper describes preliminary work carried out on the applicability of fractal geometry for differentiating between wear and contaminant particles found in mining machinery lubrication systems.Coal dust, stone dust and roadstone dust from a granite quarry were used as the contaminant particles and the particles from two crushers, which had failed whilst in service, were used to provide the wear particles.Two differing populations appeared with the wear particles having higher boundary fractals than the contaminant, but tending to spread across a wide range of fractal numbers, whereas the contaminants were lower and fairly tightly grouped.The underfractal distributions of the two populations of particles, generate straight lines when plotted on Gaussian probability paper. This leads to the probability of being able to predict the distribution of particles, in fractal terms between wear and contaminant particles.
Size Measurement of Small Magnetic Particles
Authors: Sešelj Andreja 
Published: December 2004

AbstractMany different methods for size measurement are known and since they differ in their physical principles, different results are also obtained. In the recent past, there were rapid developments in new measurement techniques and one can now quickly and routinely determine particle sizes in the very fine range. Smaller particle sizes, on the other hand, tend to increase the probability of agglomeration. The measurement of the particle sizes for magnetic materials is not well understood and this paper reports results regarding the size determination of very fine magnetic materials. Because of their dipole moment, these particles tend to agglomerate even more, which in turn causes certain difficulties during the measurements. Wet and dry laser measurement systems were compared and also magnetic materials with different permeabilities in order to establish the influence of individual factors on the measurement process and on the accuracy of the results obtained.
Relationships Between Particle Properties and Bulk Behaviour for some industrial powders
Authors: Hoffmann Alex C. , Finkers Hendrikus J. , Seegers Jacobus A. 
Published: December 2004

AbstractA series of industrial powders, most of them organic, were characterized in terms of volumetric mean size, size distribution, density, particle shape, water rentention characteristics (under a series of controlled ambient relative humidities) and loosely packed and densely packed voidages (giving the compressibility). The behaviour of the powders in powder handling apparatus (a precision powder filler) was also determined. The minimum and maximum bulk densities of the powders were related to the properties of the individual particles by means of a semi‐empirical equation. The filling capacity of the powder handling apparatus was found to be related to the maximum bulk density of the powder while the filling accuracy turned out to be related to the compressibility of the powder. Knowing these interrelations made it possible to predict the powder behaviour in the handling apparatus directly on basis of the particle properties.
Ultrasonic Investigation of Mechanical Properties of Double Base Rocket Propellants
Authors: van der Schroeff J. A. , de Boer R. S. 
Published: December 2004

AbstractFor a series of double base rocket propellants and for poly‐ methylmethacrylate (PMMA) the longitudinal and transverse sound wave velocities are measured at a frequency of 0.351 MHz in t h e temperature range of −40°C to +60°C. The relations between these acoustic properties and mechanical properties are given and the principal independent elastic constants are calculated. With increasing temperature these constants of the propellants decrease gradually, which points to a softening of the material. This is important for the functioning of the propellant grains in the rocket motors.
Consideration to the Mass Distribution of Fragments by natural‐fragmentation in combination with preformed fragments
Authors: Held M. , Kühl P. 
Published: December 2004

AbstractThe empirical formula for the distribution of fragments from rotationally‐symmetric, cylindrical warheads can be extended to the case high explosive shells. The parameters arising from this can be determined by fitting the measured results to the theoretical values. In this work possible methods of performing such a fitting procedure are discussed.
Studies of the Combustion of Solid Propellants at High Pressures
Authors: Grune D. 
Published: December 2004

AbstractTo determine burning velocities of solid propellants at high pressures, a new type of manometric bomb of 0.1 1 volume has been designed. Tightening is provided by a cartridge section from a 30 mm HS 831 steel case. 3 0 to 50 ms after the maximum, the pressure is automatically released by erosion of a 1 mm nozzle, this time lag being given by the electric igniter placed before the nozzle and by blocking it for a short time.The bomb has been applied to measure pressures p in a range up to 7000 bar as a function of loading density A for a double base propellant. The curve p(A) shows a change of slope at about 5000 bar for which explanation is still lacking.
La Commission Européenne de Normalisation des Essais d'Explosifs (changé depuis 1976: Groupe d'Etude International pour la Normalisation des Essais d'Explosifs)
Authors: Ahrens H. 
Published: December 2004

AbstractDepuis 1960 un groupe d'experts, réunis de leur propre gré, travaillent sous le nom de „Commission Européenne de Normalisation des Essais d'Explosifs„ (European Commission for the Standardization of the Tests of Explosives, Europäische Kommission zur Vereinheitlichung der Sprengstoffprüfungen).Le suivant est une courte description de cette activité depuis son origine, jusqu'à présent et pour l'avenir.
Environmental Testing of Caseless Ammunition
Authors: Schmitt D. 
Published: December 2004

AbstractCaseless ammunition is subjected to considerable loading both prior to and during use in the weapon. In order to be able to assess the suitability of the ammunition whilst still at the development stage, the types of loading which might occur were analyzed and test methods for their laboratory simulation compiled. A small calibre caseless ammunition developed at ICT was tested on this basis. It was concluded that the simulated loadings had no detrimental effect on the ammunition.
The rapid determination of nitrogen in Primary and Secondary Explosives using the Merz Method
Authors: Söntgerath H. 
Published: December 2004

AbstractThe rapid determination of nitrogen in explosives is basically possible using the Heraeus automatic Mikrorapid N as developed by Merz. The combustion of the substance takes place in pure oxygen and the nitrogen is determined volumetrically. However, when sodium and lead azides are analyzed in this way the residues of sodium and lead strongly attack the quartz of the combustion tube. In order to achieve the longest possible service life of the combustion tubes a joint investigation with BASF AG was undertaken to test other tube materials (e. g. steels, nickel, Alsint, Phythagoras) in addition to quartz. Pythagoras proved to be the most suitable material for the combustion of all explosives at 950° C in the same tube. For the determination of sodium azide a quartz finger (according to Merz) can be inserted in the tube which, at 500° C, collects the sodium residues.
Correlation of Specific Impulse and Ignition Delay in Liquid Rocket Propellants
Authors: Kishore K. , Sunitha M. R. 
Published: December 2004

AbstractTheoretically there seems to be a linear dependence between specific impulse and the ignition delay in liquid bipropellant systems. It has been observed that the plot of specific impulse versus mixture ratio of various systems based on red fuming nitric acid oxidizer show a maximum. The ignition delay versus mixture ratio plot of the same systems on the other hand show a minimum at a mixture ratio which corresponds to the maximum specific impulse. Thus, the mixture corresponding to maximum performance of a liquid bipropellant system could be qualitatively predicted from the ignition delay measurements.
Ein modifiziertes Lagrangesches Modell der Innenballistik
Authors: Heinz C. , Hensel D. 
Published: December 2004

AbstractEs wird cin modifiziertes Lagrangesches Modell der Innenballistik mitgeteilt. Dieses hat gegenüber dem bestehenden Lagrangeschen Modell den Vorteil, daR es genauer ist und daR es als Ausgangsnäherung fur ein iteratives Verfahren benutzt werden kann.
Untersuchung der Detonationsschwaden verschiedener Explosiv‐ und Sprengstoffe
Authors: Volk F. 
Published: December 2004

AbstractIn einem Sprengkessel wurden verschiedene Mengen an Nitropenta, Hexogen, Tetryl, Polyvinylnitrat und Ammonit 1 sowohl in Argon‐ Atmosphäre als auch unter Luft zur Detonation gebracht. Die hierbei gebildeten Reaktionsschwaden wurden gaschromatographisch analysiert. Der Gehalt an Stickoxiden wurde unter Verwendung eines NOx‐Chemolumineszenz‐Analysators ermittelt.Es zeigte sich, daß bereits eine geringe Menge Luft (4 Vol.%) in der Inertgasatmosphäre den NO‐Gehalt der Detonationsschwaden deutlich erhöht. Eine noch stärkere Bildung von NO wird beim detonativen Zerfall der Explosivstoffe in Luft beobachtet.Die experimentellen Ergebnisse werden diskutiert und mit Resultaten verglichen, die unter Verwendung eines thermodynamischen Rechenprogrammes erhalten wurden.
Testing of Low‐Sensitivity Explosives from the safety point of view
Authors: Wollert‐Johansen P. 
Published: December 2004

AbstractThe world's explosive industry is changing. New non‐nitroglycerin explosives of different sensitivities and physical characteristics are being developed. Many slurry explosives are mixed and pumped at elevated temperatures, and powder explosives will often be exposed to higher than ambient temperatures in the process equipment. explosives? Is it possible that different fractions of a powder explosive have different sensitivities? Which test methods can we use to evaluate sensitivity? Will the results tell us something we can apply in practical safety evaluations of explosives and process equipment? These are some of the questions we have asked. In this note some results from our work on sensitivity testing are reported. What effect has temperature on the sensitivity of “insensitive” explosives? Is i t possible that different fractions of a powder explosive have different sensitivities? Which test methods can we use to evaluate sensitivity? Will the results tell us something we can apply in practical safety evaluations of explosives and process equipment? These are some of the questions we have asked. In this note some results from our work on sensitivity testing are reported.
Empfindlichkeit der Sprengstoffe gegenüber Zündern und Zündstärke von Zündern als unsymmetrisch‐reziproke Größen
Authors: Ahrens H. 
Published: December 2004

AbstractIm Bereich chemisch einheitlicher detonationsfähiger Stoffe können auf Grund experimenteller Ergebnisse die Empfindlichkeit der Sprengstoffe gegenüber Zündern (z. B. als Ergebnisse von Versuchen mit MeGkapseln) einerseits und die Zündstarke von Zündern andererseits eindeutig und allgemein als reziproke Größen aufgefaßt werden. Auf der Seite der Sprengstoffe spielt in diesem Zusammenhang als Variable neben bestimmten Sprengstoff‐Eigenschaften die globale Dichte der Sprengkörper eine ausgeprägte Rolle. Der Dichteeinfluß auf die Zündempfindlichkeit verhalt sich dabei gerade umgekehrt wie der Dichteeinfluß auf die durch den reziproken kritischen Durchmesser festgelegte Detonationsempfindlichkeit.Geht man auf der Seite der Sprengstoffe zu heterogenen Zwei oder Mehrkomponenten‐Mischungen über, wobei es sich um Komponenten verschiedener Reaktivität (ggf. einschließlich inerter Komponenten) handelt (Gewerbliche Sprengstoffe), dann findet sich die reziproke Beziehung im Sinne einer Unsymmetrie mehr oder weniger verändert. Entscheidend dafür ist in erster Linie die Art, Menge und strukturelle Einordnung der hochsensiblen Komponente.Rückschlüsse auf die Aussagekraft verschiedener Verfahren Zündstarke‐Messung an Zündern und auf die Frage der Schaffung durch Absolutangaben definierbarer Skalen fur Initiierungs‐Sensibilität und Zündstarke werden dargelegt.
Utilisation de la Méthode par Immersion pour la Détermination de l'Energie dans les Gaz d'Explosion
Authors: Fossé C. 
Published: December 2004

AbstractC'est par une simple mesure seismographique que l'on obtient la période de pulsation de la bulle gazeuse formée sous l'eau lors de l'explosion et en résultant par calcul l'énergie dans les gaz d'explosion. Les énergies dans les gaz d'explosion pour quelques explosifs industriels sont évaluées.
The Propagation of Blasts from Solid Explosives to two‐phase media
Authors: Oved Y. , Eidelman Sh. , Burcat A. 
Published: December 2004

AbstractThe aim of this investigation is to determine the influence of the energy release from a combustible two‐phase media on the blast wave generated by an explosive charge, during the first stages of the process. For this purpose ball charges of “Composition B” were detonated in air, in pure nitrogen containing suspended solid particles of carbon, and in pure oxygen containing particles of aluminum and carbon. The blast wave's velocity was measured in all the media using fast frame camera 300,000 f.p.s. and streak photography at 2 mm/μs. The influence of release or absorption of energy by the medium was investigated by comparing experiments done in inert media with those conducted in combustible media while other parameters are kept constant.Kozorezov's triple isentrope model was compared to the results, and good agreement is found. The article contains detailed information on the experiments and the calculations performed.
Etude par Résonance Magnétique Nucléaire Impulsionnelle de la Plastification du Nitrate de Polyvinyle
Authors: Michaud C. , Arnaud B. , Adenis J. C. , Marechal E. 
Published: December 2004

AbstractLa Résonance Magnétique Nucléaire Impulsionnelle permet l'étude de systèmes constitués de plusieurs phases de mobilités différentes. Nous présentons ici une application de cette technique à l'examen du phénomène de plastification du nitrate de polyvinyle au phtalate de dibutyle. Dans ce matériau, on met ainsi en évidence les phases suivantes:

polymère rigide,
polymère mobile,
plastifiant rigide,
plastifiant mobile.
Ces différentes phases sont suivies quantitativement en fonction du taux de plastifiant et de la température.
Thermoanalytical Determination of Tetrazene in Primer Mixtures
Authors: Krien G. 
Published: December 2004

AbstractThe heat of decomposition allows the quantitative determination of tetrazene in primer mixtures by DSC or DTA. The standard deviation of the method is 0.02 mg if the content in tetrazene is in the range of 0.1 mg to 1.5 mg. The confidence interval of a measurement is 0.03 mg tetrazene. This is sufficient for control measurements in view of the large variations introduced during sampling of tetrazene in small amounts of primer. The low weight required by the method (2 mg or more) enables the determination of tetrazene in friction compositions of a detonator or in percussion caps. This is important when malfunctions have to be analyzed.
Structure moléculaire des derivés nitrés aromatiques. III. Effet de la corrélation électronique sur le calcul des états singulets à l'équilibre et hors d'équilibre, le long de la liaison CNO2; analyse de populations de charges sur le groupe CNO2
Authors: Odiot S. , Blain M. , Leclercq J. M. , Leclercq J. , Fliszar S. , Boileau J. , Fleury G. 
Published: December 2004

AbstractLes distributions électroniques de charges dans les états singulets du nitrobenzène, des meta‐ et para‐dinitrobenzènes et du 1,3,5‐trinitrobenzène ont été calculées en fonction de la vibration de valence totalement symétrique du ou des groupements CNO2 par calcul CNDO/S avec IC incluant mono et biexcitations. L'effet de la corrélation électronique sur le niveau fondamental calculé en STO‐3 G et les états excités est pris en considération.
Nitramine Solid Rocket Propellants with Reduced Signature
Authors: Klöhn W. , Eisele S. 
Published: December 2004

AbstractSolid rocket propellants containing nitramine are considerably superior to doublebase propellants, both as regards their performance and mechanical properties. The pressure exponent of non‐modified nitramine propellants is n ≥ 0.9. The possibility of changing the burning rate or, respectively, the pressure exponent has, however, only been realisable to a restricted extent up till now in propellants with an increased nitramine content. In the following propellant system containing nitramine, the effects of ammonium perchlorate on burning behaviour are studied:

ammonium perchlorate (AP)
hexogen (RDX)
nitroglycerin (NG), or trimethylolethane trinitrate (TMETN)
polyurethane binder (PU)
AP concentrations already as great as 10% produce considerable changes in the burning behaviour of the propellants described above. It is possible to reduce the pressure exponent by the addition of ammonium perchlorate from n ≥ 0.9 to n ≤ 0.65. The burning rates may also be influenced with AP concentrations ≤ 20% and by varying the AP particle size by the factor of 2. All the propellants prepared were easily castable and showed exceptionally good viscoelastic properties (strain at break εR > 200%) in the temperature range between −40 °C to + 50 °C. The thermal chemical stability is not influenced negatively in any way by the combination of nitric acid esters and ammonium perchlorate.
Determination of Chemical and Mechanical Properties of Double Base Propellants during Aging
Authors: Volk F. , Bohn M. A. , Wunsch G. 
Published: December 2004

AbstractThermal and mechanical stability of rocket and gun propellants are very important properties with regard to safety during storage and handling and to the interior ballistics behavior during combustion.However, our knowledge of how these properties are connected is poor. In order to better understand the aging behavior of double base propellants, the following properties were measured between 60 °C and 90 °C: the depletion of the stabilizers, the degradation of the molecular weights of nitrocellulose and the decrease of the mechanical properties (tensile strength and strain at break).The evaluation of the kinetic parameters of the different aging processes mentioned has shown that stabilizer depletion, molecular weight degradation of nitrocellulose and decrease of mechanical properties must be closely connected.