Experimental study on oscillating behaviour in a small-scale compartment fire

To investigate fire behaviour in a compartment, the effect of ventillation factor and fuel surface area was studied experimentally by using methanol as a fuel. A limit of stable combustion appeared at a small ventillation factor. As the fuel surface became larger, the stable combustion limit increased. Oscillating combustion was observed in both an unstable combustion region and a stable combustion region near the boundary of these regions. In the unstable combustion region, extinction followed the oscillating combustion. On the other hand, in the stable region the oscillating combustion lasted until the fuel was exhausted. The period of the oscillating combustion was 1·–1·5 s in the stable combustion region.     

MOLECULAR EVENT EXTRACTION FROM LINK GRAMMAR PARSE TREES IN THE BIONLP’09 SHARED TASK

The BioNLP’09 Shared Task deals with extracting information on molecular events, such as gene expression and protein localization, from natural language text. Information in this benchmark are given as tuples including protein names, trigger terms for each event, and possible other participants such as bindings sites. We address all three tasks of BioNLP’09: event detection, event enrichment, and recognition of negation and speculation. Our method for the first two tasks is based on a deep parser; we store the parse tree of each sentence in a relational database scheme. From the training data, we collect the dependencies connecting any two relevant terms of a known tuple, that is, the shortest paths linking these two constituents. We encode all such linkages in a query language to retrieve similar linkages from unseen text. For the third task, we rely on a hierarchy of hand‐crafted regular expressions to recognize speculation and negated events. In this paper, we added extensions regarding a post‐processing step that handles ambiguous event trigger terms, as well as an extension of the query language to relax linkage constraints. On the BioNLP Shared Task test data, we achieve an overall F1‐measure of 32%, 29%, and 30% for the successive Tasks 1, 2, and 3, respectively.     

Performance of potassium-promoted catalysts for NO x and soot removal from simulated diesel exhaust

In order to elucidate the effect of support in the catalytic performance, two selected potassium-promoted catalysts (K1Cu/beta and KCu2/Al₂O₃) were tested for the simultaneous NO _x /soot removal from a simulated diesel exhaust. For comparative purpose, the behaviour of a platinum catalyst (Pt/beta) was also studied. Isothermal experiments revealed that the potassium-promoted catalysts show a high activity for NO _x /soot removal in the 350–450 °C temperature range. In addition, the catalysts present the advantage that the main reaction products are N₂ and CO₂. Among the catalysts tested, KCu2/Al₂O₃ presents the best global performance at 450 °C: the highest soot consumption rate, even higher than the platinum catalysts, and a high NO _x reduction.     

Preparation of positive‐temperature coefficient heaters using platinum‐catalyzed silicone rubber

Various output heaters were extruded with acetylene black–filled platinum‐catalyzed silicone rubber. The resistivity–temperature behavior of extruded heaters exhibited a positive‐temperature coefficient (PTC) effect without any negative‐temperature coefficient (NTC) effect. Resistivity and thermal reproducibility of the extruded heaters were investigated during heating and cooling cycles at an applied voltage of 220 V. These heaters initially showed poor reproducibility of resistivity during the repeated cycles and this effect increased significantly as the acetylene black content decreased. PTC effect and electrical reproducibility were improved significantly during the thermal ageing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1611–1617, 2004     

A study on the polymer layer-forming phenomena in a rotating disk polycondensation reactor

An experimental study is reported on the measurement of polymer melt film thickness in a rotating disk polycondensation reactor. The layer thickness of molten poly(ethylene terephthalate) on a rotating disk was measured at 280°C using an electrical conductivity probe at different radial and angular positions. It was observed that the polymer film thickness was not uniform in both radial and angular positions, particularly for high molecular weight polymers. For the slowly rotating disk system employed in our experimental study, the disk rotational speed and gravity effects on the polymer-layer formation were found to be quite significant. The experimental results were used to develop an empirical correlation for the calculation of polymer film thickness and polymer melt holdup on a rotating disk. © 1995 John Wiley & Sons, Inc.     

Modeling of a continuous rotating disk polycondensation reactor for the synthesis of thermoplastic polyesters

A dynamic multicompartment model is proposed for a continuous flow rotating disk reactor for the finishing stage melt polycondensation of poly(ethylene terephthalate). In the multicompartment reactor model, ethylene glycol is removed from both the bulk melt phase and the film phase formed on the rotating disks. The specific interfacial area for the film phase is estimated using the empirical correlation for polymer film thickness, and the mass transfer coefficient is calculated using the penetration theory. The mass transfer enhancement factor is introduced to account for the increased interfacial area due to ethylene glycol bubbles. The effects of reactor design and operating parameters on molecular weight and ethylene glycol removal have been investigated through model simulations. In particular, a detailed analysis is presented on the ethylene glycol removal rate from the two phases. © 1996 John Wiley & Sons, Inc.     

Numerical simulation of friction stir spot welding process for aluminum alloys

Thermo-mechanical simulations of the Friction Stir Spot Welding (FSSW) processes were performed for AA5083-H18 and AA6022-T4, utilizing commercial Finite Element Method (FEM) and Finite Volume Method (FVM) codes, which are based on Lagrangian and Eulerian formulations, respectively. The Lagrangian explicit dynamic FEM code, PAM-CRASH, and the Eulerian Computational Fluid Dynamics (CFD) FVM code, STAR-CD, were utilized to understand the effect of pin geometry on weld strength and material flow under the unsteady state condition. Using FVM code, material flow patterns near the tool boundary were analyzed to explain weld strength difference between welds by a cylindrical pin and welds by a triangular pin, whereas the frictional energy concept using the FEM code had a limited capacity to explain the weld strength difference.     

Poly(9‐vinylcarbazole)/silver composite nanotubes and networks formed at the air–water interface

Silver‐nanoparticle‐doped poly(9‐vinylcarbazole) (PVK) nanocomposites were prepared via the reduction of Ag⁺ ions and the self‐assembly of PVK on AgNO₃ aqueous solution surfaces. The formed composite nanostructures depended strongly on the experimental temperature. Thick round disks of PVK surrounded by discrete Ag nanoparticles and/or with irregular holes formed at room temperature; nanotubes and micronetworks doped with Ag nanoparticles formed at about 30–40°C, and networks formed at higher temperature. Further investigation revealed that the nanotubes were transformed from thin round disks. The length of the PVK/Ag composite nanotubes were longer than 10 μm, and the average size of the embedded Ag nanoparticles was found to be about 3.5 nm. The composite networks were composed of round pores with diameters of several hundred nanometers and fine silver nanoparticles embedded in the thin polymer films that covered the pores. The formation of the nanotubes was a very interesting self‐assembly phenomenon of the polymer at the air–water interface that has not been reported before. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Electrochemical migration behaviour of Cu, Sn, Ag and Sn63/Pb37

The Electrochemical Migration (ECM) behaviour of leaded surface finishes was compared to other surface finishes that are applied in the electronics manufacturing. The studied surface finishes were as follows: bare copper (bCu), immersion tin (iSn), immersion silver (iAg) and Sn63Pb prepared by HASL (Hot Air Solder Leveling). The results were evaluated by Water drop test with the calculation of the Mean Time to Failure (MTTF) and by the investigation of the composition of the dendrites. The results have shown some contradictions relating bare copper and HASL compared to the ECM ranking published previously (Harsányi and Inzelt in Microelectron Reliab 41:229–237, 2001; Yu et al. in J Mater Sci: Mater Electron 17(3):229–241, 2006). The copper and the HASL can change their places in the ECM ranking depending on the technological circumstances of the investigations. This impact can be caused by the composition of lead alloys (eutectic or not), the solubility parameters of the metal hydroxides; the oxidation state of the copper surface, etc. Further and theoretical explanations and the necessary fine adjustment of the migration models are discussed in the paper.