Densification of nanocrystalline Y2O3 ceramic powder by spark plasma sintering

Nanocrystalline Y₂O₃ powders with 18 nm crystallite size were sintered using spark plasma sintering (SPS) at different conditions between 1100 and 1600 °C. Dense specimens were fabricated at 100 MPa and 1400 °C for 5 min duration. A maximum in density was observed at 1400 °C. The grain size continuously increased with the SPS temperature into the micrometer size range. The maximum in density arises from competition between densification and grain growth. Retarded densification above 1400 °C is associated with enhanced grain growth that resulted in residual pores within the grains. Analysis of the grain growth kinetics resulted in activation energy of 150 kJ mol^?1 and associated diffusion coefficients higher by 10³ than expected for Y³⁺ grain boundary diffusion. The enhanced diffusion may be explained by combined surface diffusion and particle coarsening during the heating up with grain boundary diffusion at the SPS temperature.     

Synthesis and structural characterization of a liquid polyisoprene bearing amidoxime end groups

Azo-bis(isobutyroamidoxime) was synthesized and used as functionalized initiator to prepare a liquid isoprene bearing amidoxime end groups via radical polymerization. The polymer was characterized by FT-IR, Gel Permeation Chromatography and NMR. In particular, the structure of the polymer was investigated using 1D and 2D NMR techniques. The distribution of the different isoprene units (1,4-trans, 1,4-cis, 1,2 and 3,4), as well as the structure of the amidoxime end-groups was determined. It was found that the structure of the end groups was governed by the steric hindrance of the initiator. Only 1,4 and 4,1 functionalized end units were evidenced, with a majority of 4,1 end units.     

Multimodal person discovery in broadcast TV: lessons learned from MediaEval 2015

Multimedia Tools and Applications - We describe the “Multimodal Person Discovery in Broadcast TV” task of MediaEval 2015 benchmarking initiative. Participants were asked to return the...     

Postwar Science in Divided Europe: A Continuing Cooperation

This paper is devoted to an outline of certain aspects of international scientific cooperation and exchange between Eastern and Western European countries from 1950 to 1989, with an emphasis on mathematics, biochemistry and neuroscience.     

Crowding Studies and Urban Life: A Critical Review

In recent years, a great deal of speculation and research has appeared on the topic of whether population density has serious social psychological consequences. In this article, we review the crowding literature with particular concern for its implications for urban life. First, we examine the extant research and draw two conclusions: that much of the work is methodologically or conceptually limited; and, that density, though perceived as unpleasant, does not appear to have definite and consistent detrimental effects. Second, we consider the theoretical relevance of this literature to urban studies, find it lacking in certain respects, and suggest solutions to the problem of relevance. Finally, we present several theoretical frameworks for guiding future research on the effects of urban density.     

Plastic deformation of dense nanocrystalline yttrium oxide at elevated temperatures

Nanocrystalline yttrium oxide, Y₂O₃ with 110 nm average grain size was plastically deformed between 800 °C and 1100 °C by compression at different strain rates and by creep at different stresses. The onset temperature for plasticity was at 1000 °C. Yield stress was strongly temperature dependent and the strain hardening disappeared at 1100 °C. The polyhedral and equiaxed grain morphology were preserved in the deformed specimens. The experimentally measured and theoretically calculated stress exponent n = 2 was consistent with the plastic deformation by grain boundary sliding. Decrease in the grain size was consistent with decrease in the brittle to ductile transition temperature.     

Energy Aware Signal Processing for Software Defined Radio Baseband Implementation

The fast pacing diversity and evolution of wireless communications require a wide variety of baseband implementations within a short time-to-market. Besides, the exponentially increased design complexity and design cost of deep sub-micron silicon highly desire the designs to be reused as much as possible. This yields an increasing demand for reconfigurable/ programmable baseband solutions. Implementing all baseband functionalities on programmable architectures, as foreseen in the tier-2 SDR, will become necessary in the future. However, the energy efficiency of SDR baseband platforms is a major concern. This brings a challenging gap that is continuously broadened by the exploding baseband complexity. We advocate a system level approach to bridge the gap. Specifically, we fully leverage the advantages (programmability) of SDR platforms to compensate its disadvantages (energy efficiency). Highly flexible and dynamic baseband signal processing algorithms are designed and implemented to exploit the abundant dynamics in the environment and the user requirement. Instead of always performing the best effort, the baseband can dynamically and autonomously adjust its work load to optimize the average energy consumption. In this paper, we will introduce such baseband signal processing techniques optimized for SDR implementations. The methodology and design steps will be presented together with 3 representative case studies in HSDPA, WiMAX and 3GPP LTE.