Combustion Behavior of Fluorocarbon/Boron/AP Propellant at high pressure

Thermal decomposition and the burning properties of fluorocarbon/boron/AP propellant granule have been investigated. The fluoro-carbon binder (FBDR) was oxidized by the decomposition products of admixed ammonium perchlorate (AP) and its decomposition region was 150°C lowered in the slow thermolysis. The boron particles, however reacted with neither FBDR nor AP at 550°C. In the micro-motor tests, the boron particles completely burnt at a pressure range of from 30 MPa to 80 MPa in a short period of time (one millisecond) even at a low characteristic exhaust velocity. Minimum free volume, however, was needed to complete the combustion reaction in the chamber case. The characteristic exhaust velocity significantly decreased at below the characteristic chamber length of 11 cm. The boronized propellant showed low temperature sensitivity between −30°C and 60°C.     

The Calcium Phosphate Matrix of FGF-2-Apatite Composite Layers Contributes to Their Biological Effects

The purpose of the present study was to fabricate fibroblast growth factor (FGF)-2-apatite composite layers on titanium (Ti) pins in one step at 25 °C using a supersaturated calcium phosphate (CaP) solution, and to evaluate the physicochemical characteristics and biological effects of the coated Ti pins compared with coated Ti pins fabricated at 37 °C. Ti pins were immersed in a supersaturated CaP solution containing 0.5, 1.0, or 2.0 µg/mL FGF-2 at 25 °C for 24 h (25F0.5, 25F1.0, and 25F2.0) or containing 4.0 µg/mL FGF-2 at 37 °C for 48 h (37F4.0). Except for the 25F0.5, the chemical compositions and the mitogenic activity levels of FGF-2 of the composite layers formed by these two methods were similar, except for the Ca/P molar ratio, which was markedly smaller at 25 °C (1.55–1.56 ± 0.01–0.02, p = 0.0008–0.0045) than at 37 °C (1.67 ± 0.11). Thus, either the apatite was less mature or the amount of amorphous calcium phosphate was higher in the composite layer formed at 25 °C. In vivo, the pin tract infection rate by visual inspection for 37F4.0 (45%) was lower than that for 25F1.0 (80%, p = 0.0213), and the rate of osteomyelitis for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0341). The extraction torque for 37F4.0 (0.276 ± 0.117 Nm) was higher than that for 25F0.5 (0.192 ± 0.117 Nm, p = 0.0142) and that for 25F1.0 (0.176 ± 0.133 Nm, p = 0.0079). The invasion rate of S. aureus for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0110). On the whole, the FGF-2-apatite composite layer formed at 25 °C tended to be less effective at improving fixation strength in the bone-pin interface and resisting pin tract infections. These results suggest that the chemistry of the calcium phosphate matrix that embeds FGF-2, in addition to FGF-2 content and activity, has a significant impact on composite infection resistance and fixation strength.     

Prediction of stress-strain relationship with an improved Anand constitutive Model For lead-free solder Sn-3.5Ag

An improved Anand constitutive model is proposed to describe the inelastic deformation of lead-free solder Sn-3.5Ag used in solder joints of microelectronic packaging. The new model accurately predicted the overall trend of steady-state stress-strain behavior of the solder for the temperature range from 233 K to 398 K and the strain rate range from 0.005 s/sup -1/ to 0.1 s/sup -1/. h/sub 0,/ a constant in the original Anand model, was set to a function of temperature and strain rate in the proposed model. Comparison of the experimental results and simulated results verified that the improved Anand model with modifying h/sub 0/ to a function reasonably simulated the inelastic stress-strain relationships.     

Particle growth of magnesium alkoxide as a carrier material for polypropylene polymerization catalyst

Images from scanning electron microscopy, transmission electron microscopy and X-ray diffraction profiles of typical magnesium diethoxide (MGE) particles obtained by the reaction of ethanol, metal magnesium and iodine showed the round MGE particle (tertiary particle) had a layer structure consisting of many crystalline fragments (secondary particles) comprising many minute crystals (primary particles). It was clearly shown that each precipitated secondary particle had not agglomerated, but had repeatedly grown and combined with others. From the investigation of the course of a reaction, it was suggested the MGE crystals grown on Mg metal exfoliated as “lump-like” seeds, and crystal growth on seeds proceeded such that the shapes of the final MGE particles were more spherical than those of their seeds. It was presumed from a model reaction that the enhancement of MGE solubility by I₂ addition to form the quasi-stable complex nMg(OEt)₂·MgI₂·mEtOH was the key process in the formation of plate crystals. The relationship between the size of crystalline fragments and crystallization rate (reaction rate, MGE solubility) was discussed.The catalyst, when prepared using MGE as the carrier material, exhibited exceptionally high polymerization activity than when it was prepared with MgCl₂ alcohol complex (MgCl₂·ROH). We presume that this is because particles of the MGE-based catalyst are porous, and because the formation of active species of the supported Ti and monomer diffusion progressed adequately from the surface of the particle to its internal parts.     

Sensor Planning for Mobile Robot Localization---A Hierarchical Approach Using a Bayesian Network and a Particle Filter

In this paper, we propose a hierarchical approach to solving sensor planning for the global localization of a mobile robot. Our system consists of two subsystems: a lower layer and a higher layer. The lower layer uses a particle filter to evaluate the posterior probability of the localization. When the particles converge into clusters, the higher layer starts particle clustering and sensor planning to generate an optimal sensing action sequence for the localization. The higher layer uses a Bayesian network for probabilistic inference. The sensor planning takes into account both localization belief and sensing cost. We conducted simulations and actual robot experiments to validate our proposed approach.     

Cure study of epoxy resin reinforced with multiwalled carbon nanotubes by Raman and luminescence spectroscopy

Carbon nanotubes (CNTs) were annealed at high temperature under vacuum, followed by a chemical treatment using acids and ethylenediamine. The presence of acid and amine chemical groups on CNT surface was confirmed by infrared spectra. The amount of iron remaining in the CNTs after the treatments was evaluated by thermogravimetry and by energy dispersion spectroscopy. The crystalline property of CNTs was evaluated by Raman spectroscopy, showing that the acid treatment performed after the thermal treatment did not damage the nanotubes walls. Micrographs showed that the most dispersed CNTs were obtained after the amine functionalization step. The curing process of the neat resin and composites was studied by Raman and Luminescence spectroscopies and both techniques showed similar results. The presence of CNTs, functionalized or not, increased the cure degree of the epoxy resin when the same cure time was used in the comparison. Nanocomposites synthesized with annealed CNT and acid‐treated CNT had cure rates considerably higher at the beginning of the reaction. The difference in the cure rate was explained by means of the sample's homogeneity and the presence of chemical groups. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mathematical modeling of meniscus profile and melt flow in electromagnetic casters

The paper describes a mathematical model which predicts the meniscus shape and melt flow in an electromagnetic caster. Computations were carried out for the two types of caster (with and without a screen to shape the magnetic field) in commercial use. The dependence of meniscus shape on parameters such as inductor geometry, placement, current, and frequency, as well as screen properties and placement, was determined. Calculated velocities showed agreement with measurements of other investigators on a physical model and an actual caster. The effect of an auxiliary low frequency inductor on melt flow was also computed.     

Measurements of the (n, np+d) activation cross sections with 13.4–14.9 MeV neutrons using a fusion neutronics source/JAERI

The activation cross sections for 20 (n, np+d) reactions were measured in the energy range between 13.4 and 14.9 MeV by the activation method. The mass-separated isotopes of ⁸⁷Sr, ^95,100Mo, ¹⁰⁴Ru, ¹⁰⁶Pd, ^113,116Cd, ^118,119,120Sn, ^123,128,130Te, ^184,186W, and ^189,190Os were irradiated. The 16 cross sections, excepting those for ¹¹⁸Sn, ¹²⁸Te and ^184,186W, were obtained for the first time. The d–T neutron source of the fusion neutronics source (FNS) at the Japan Atomic Energy Research Institute (JAERI) was used for irradiation. All cross section values were determined relative to that of the ²⁷Al (n, ) ²⁴Na reaction (ENDF/B-VI). To measure weakly induced activities, an efficiency calibration technique with a well-type HPGe detector was applied. The present results were compared with the comprehensive evaluated data in the JENDL-3.3, the JENDL-Activation File, the ENDF/B-VI and the FENDL/A-2.0. Most of the data in the JENDL-3.3 and the JENDL-Activation File were in good agreement with the present result. However, relative to our values, 13 of the 20 evaluated data in FENDL/A-2.0 were overestimated more than 2 times or underestimated by less than one tenth.