AXIAL PHASES DISTRIBUTION AND HOMOGENIZATION IN THREE-PHASE FLUIDIZED BEDS

We have investigated the axial distribution of the liquid phase in a three-phase fluidized bed in which the particles were glass beads of two different diameters, 710-850 μm and 2 mm. Two methods were used to reduce the axial heterogeneity and homogenize the bed: the use of packing elements and the addition of a small quantity of a high molecular weight polymer. The use of packing elements was shown to be very efficient in controlling phases distribution in the bed. The packing consisted of 1 mm thick steel horizontal plates punched and stretched to obtain parallelogram-shaped openings. The addition of a high molecular weight polyisobutylene (BASF Oppanol B246, M_u, =6.15 Lo⁶) on the phase distribution was also studied. Low polymer concentrations up to 397 ppm (based on the liquid phase) were investigated. The addition of the polymer reduced bubble coalescence and allowed for a better distribution of the phases.     

Re-examining the causal structure of information technology impact research

About 20 years ago, Markus and Robey noted that most research on IT impacts had been guided by deterministic perspectives and had neglected to use an emergent perspective, which could account for contradictory findings. They further observed that most research in this area had been carried out using variance theories at the expense of process theories. Finally, they suggested that more emphasis on multilevel theory building would likely improve empirical reliability. In this paper, we reiterate the observations and suggestions made by Markus and Robey on the causal structure of IT impact theories and carry out an analysis of empirical research published in four major IS journals, Management Information Systems Quarterly (MISQ), Information Systems Research (ISR), the European Journal of Information Systems (EJIS), and Information and Organization (I&O), to assess compliance with those recommendations. Our final sample consisted of 161 theory-driven articles, accounting for approximately 21% of all the empirical articles published in these journals. Our results first reveal that 91% of the studies in MISQ, ISR, and EJIS focused on deterministic theories, while 63% of those in I&O adopted an emergent perspective. Furthermore, 91% of the articles in MISQ, ISR, and EJIS adopted a variance model; this compares with 71% from I&O that applied a process model. Lastly, mixed levels of analysis were found in 14% of all the surveyed articles. Implications of these findings for future research are discussed.     

A Note on EMP Safety Hazards

The character of transient electric fields induced in spherical homogeneous tissue models of man and animals by incident electromagnetic fields similar to that originating from lightning and EMP generators has been theoretically determined. The magnitude of the induced fields is found to be approximately proportional to the time rate of change of the incident field and independent of the pulsewidth. It was also found that maximum EMP induced field in spherical shaped bodies is nearly proportional to the radius of the body. Therefore, for EMP safety standards, more consideration should be given to the time rate of change of the incident field rather than to the pulsewidth, and when laboratory animal data are used as a guide they should be extrapolated to account for body size.     

The First Report on Scheme Revisited

Higher-Order and Symbolic Computation -     

Silver coated vapor-grown-carbon nanofibers for effective reinforcement of polypropylene-polyaniline

This work utilizes a modification of our process of polymer entrapment in silver to deposit silver crystals on carbon nanofibers at different relative concentrations. The experimental procedure and the characteristics of silver coated nanofibers are presented in detail. The resulting nanofibers are then melt-mixed with a polypropylene-polyaniline blend to form a uniform dispersion that is finally extruded to produce continuous monofilament composites of high axial orientation. The reinforcement effect of the silver coated nanofibers, manifested in the mechanical properties of the monofilament composites, is 3-5 folds higher than that of the pristine nanofibers due to the improved stress transfer mechanism of the former. Additional attractive properties of the new system may result from its anisotropic crystalline structure, enhanced thermal stability, potential electrical conductivity and antibacterial behavior.     

A Brief Survey of our Contribution to Stable Carbene Chemistry

This personal account summarizes our work, beginning with the discovery of the first stable carbene in 1988 up until the recent isolation of mesoionic carbenes. It explains why we have moved our focus from acyclic to cyclic carbenes, and shows that these stable species are not limited to the role of ligand for transition metals, but that they are also powerful agents for the activation of small molecules, and for the stabilization of highly reactive diamagnetic and paramagnetic species.     

Conception d’une solution de sélection de passerelles Internet dans les réseaux ad hoc

In the past few years, Internet has raised increasing interest in various areas including research, education, and business. The number of people accessing the Internet at work or at home has increased considerably, just like the number of services offered (email, e-commerce, search engines, e-learning, e-government, etc.). Ad hoc networks were generally viewed as stand-alone networks, where communications are only supported between nodes in the network such as in military and rescue operations. The lack of connectivity to the wired infrastructure enables simple management and deployment, but limits the applicability of ad hoc networks to today’s scenarios, which require connectivity outside the ad hoc network and particularly to the Internet. However, to reach this goal, a number of problems need to be resolved because of the dynamic nature of such environment. In this article, we describe a new solution for dynamic gateway selection based on quality of service (QoS) criteria. The underlying architecture is based on a pro-active routing protocol.     

An improved observation model for super-resolution under affine motion.

Super-resolution (SR) techniques make use of subpixel shifts between frames in an image sequence to yield higher resolution images. We propose an original observation model devoted to the case of nonisometric inter-frame motion as required, for instance, in the context of airborne imaging sensors. First, we describe how the main observation models used in the SR literature deal with motion, and we explain why they are not suited for nonisometric motion. Then, we propose an extension of the observation model by Elad and Feuer adapted to affine motion. This model is based on a decomposition of affine transforms into successive shear transforms, each one efficiently implemented by row-by-row or column-by-column one-dimensional affine transforms. We demonstrate on synthetic and real sequences that our observation model incorporated in a SR reconstruction technique leads to better results in the case of variable scale motions and it provides equivalent results in the case of isometric motions.