Design and Prototyping of a Switching Beam Disc Antenna for Wideband Communications

The design procedure for a switching beam antenna for wireless communication systems is given. The antenna can rotate the beam over the whole azimuthal angle exploiting its geometrical and electrical cylindrical symmetry. The required directivity and the beam rotation are provided by a sequential insertion of metallic posts into the radial waveguide that forms the main body of the antenna. The first stage of the design involves setting up the dimensions of an omnidirectional antenna, to which the desired directivity is subsequently provided. After optimization to maximize the impedance bandwidth, the final antenna was prototyped. A comparison between simulated results and experimental data is presented     

Transient gasification and syngas formation from coal particles in a fixed‐bed reactor

An experimental investigation on gasification and syngas formation from coal particles in a fixed‐bed reactor is conducted; particular attention is paid to the transient reaction dynamics. Three different coals, including two high‐volatile coals and a low‐volatile coal, are taken into consideration. In the initial reaction period, a two‐stage reaction is clearly observed; specifically, an exothermic reaction followed by an endothermic reaction is exhibited. Meanwhile, seeing that the devolatilization and pyrolysis reactions are pronounced, the initial concentrations of H₂ and CH₄ are relatively high, especially for the former. With increasing time, the interaction between coal and char particles is dominated by the latter, the concentrations of CO and CO₂ thus become higher. From the observation of syngas combustion, the entire gasification intensity proceeds from intensified growth, rapid decay, and then to progressive decay with increasing reaction time. For the two high‐volatile coals, the mass depletion is enhanced markedly once the reaction temperature is as high as 1000°C, whereas it is insensitive to the temperature for the low‐volatile coal. Nevertheless, it is found that, based on the weights of moisture and volatile matter, their relative release ratio from the low‐volatile coal is better than that from the high‐volatile coals. This implies that the final devolatilization and pyrolysis extent is not determined by coal grade. Copyright © 2006 John Wiley & Sons, Ltd.     

Performance and its relation with productivity in Lotkaian systems

In general information production processes (IPPs), we define productivity as the total number of sources but we present a choice of seven possible definitions of performance: the mean or median number of items per source, the fraction of sources with a certain minimum number of items, the h-, g-, R- and h_w-index. We give an overview of the literature on different types of IPPs and each time we interpret “performance” in these concrete cases. Examples are found in informetrics (including webometrics and scientometrics), linguistics, econometrics and demography. In Lotkaian IPPs we study these interpretations of “performance” in function of the productivity in these IPPs. We show that the mean and median number of items per source as well as the fraction of sources with a certain minimum number of items are increasing functions of the productivity if and only if the Lotkaian exponent is decreasing in function of the productivity. We show that this property implies that the g-, R- and h_w-indices are increasing functions of the productivity and, finally, we show that this property implies that the h-index is an increasing function of productivity. We conclude that the h-index is the indicator which shows best the increasing relation between productivity and performance.     

An analysis of the course of psychoanalysis: The case for a unitary theory.

Psychoanalysis started out as a unitary theory to encompass disparate observable phenomena. Symptoms, dreams, character traits, psychopathology, and normal psychology all rested on the same explanatory intrapsychic base. Since then, theory has grown by accretion and by the creation of alternative theoretical systems. Various fallacies and flaws in logic have played a part in this development. The current state of pluralism, in my view, has resulted in a theoretical fragmentation that reduced the power and inspiration intrinsic to a unified, coherent psychoanalytic theory. I describe a total composite unitary theory, cumulative over the century, in which all valid and enduring elements of competitive psychoanalytic theories are included. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-referenced assay method for photonic crystal biosensors: Application to small molecule analytes

Using an image-based method for label-free detection of biochemical binding density distribution on the surface of a photonic crystal biosensor embedded within standard format multiwell microplates, a new method for automatic referencing of assay errors due to variability in the bulk refractive index of the analyte test sample is demonstrated. The new method involves application of the immobilized ligand upon the biosensor surface as a small spot, so that uncoated regions of a microplate well may serve as an accurate reference for the “active” regions containing the ligand. Due to the high spatial resolution of the image-based detection approach, each well in the microplate may be represented by hundreds of independent measurements of biochemical binding density, as measured by the shift in reflected wavelength from the photonic crystal biosensor. A linear plot of detected analyte density as a function of immobilized ligand density is constructed, in which the slope represents the ligand/analyte affinity and the intercept represents common-mode error effects. Streptavidin–biotin is used as a ligand–analyte model system to demonstrate the ability of this method to separate intentionally introduced bulk refractive index errors from the detection of a small molecule analyte. This referencing approach will be important in the context of small molecule drug compound library screening, where drug compounds within a large library are often suspended in solutions of inconsistent bulk refractive index.     

Unique Sink Orientations of Grids

We introduce unique sink orientations of grids as digraph models for many well-studied problems, including linear programming over products of simplices, generalized linear complementarity problems over P-matrices (PGLCP), and simple stochastic games. We investigate the combinatorial structure of such orientations and develop randomized algorithms for finding the sink. We show that the orientations arising from PGLCP satisfy the Holt-Klee condition known to hold for polytope digraphs, and we give the first expected linear-time algorithms for solving PGLCP with a fixed number of blocks. The first and the third author acknowledge support from the Swiss Science Foundation (SNF), Project No. 200021-100316/1. Part of this research was done at the 2004 Barbados Undercurrent Workshop Polyhedra, Convex Geometry, and Optimization at Bellairs Research Institute, McGill University.     

Direct assembly process: a novel fabrication technique for large strain ionic polymer transducers

Ionic polymer transducers (IPT) consist of an ion-exchange membrane plated with flexible conductive electrodes on their outer surface. Compared to other types of electromechanical transducers, ionomeric transducers have the advantage of high-strain output (>9%), low-voltage operation (<5 V), and high sensitivity in the charge-sensing mode. A novel fabrication technique for ionic polymer transducers named the Direct Assembly Process (DAP) was developed in this paper. The DAP allows the use of any type of ionomer, diluent, and conducting powder in the transducer, and permits the exploration of any novel ionomeric design. In this paper the effect of diluent content of the IPT, electrode thickness, and composition were optimized in term of maximum peak strain and strain rate generated by an IPT. Decreasing viscosity and increasing polarity and content of the diluent were demonstrated to increase the strain rate of an IPT. The thickness of the electrode was varied and correlated with the maximum strain generated due to a 2 V step input. This study also demonstrated that RuO₂ composition has an optimal loading of 42 vol%, while SWNT electrodes have an optimal performance at around 30 vol%.     

Modelling successive h-indices

From a list of papers of an author, ranked in decreasing order of the number of citations to these papers one can calculate this author’s Hirsch index (or h-index). If this is done for a group of authors (e.g. from the same institute) then we can again list these authors in decreasing order of their h-indices and from this, one can calculate the h-index of (part of) this institute. One can go even further by listing institutes in a country in decreasing order of their h-indices and calculate again the h-index as described above. Such h-indices are called by Schubert [2007] “successive” h-indices. In this paper we present a model for such successive h-indices based on our existing theory on the distribution of the h-index in Lotkaian informetrics. We show that, each step, involves the multiplication of the exponent of the previous h-index by 1/α where α > 1 is a Lotka exponent. We explain why, in general, successive h-indices are decreasing. We also introduce a global h-index for which tables of individuals (authors, institutes,...) are merged. We calculate successive and global h-indices for the (still active) D. De Solla Price awardees.     

Phase equilibria and thermal analysis of Si–C–N ceramics

The phase reactions, crystallization behaviour and thermal degradation of two Si–C–N ceramics derived from precursors VT50 and NCP200, respectively, were studied by means of CALPHAD type thermodynamic calculations and experimental investigations by DTA/TG, XRD and SEM/EDX. The phase reaction Si₃N₄+3C=3SiC+2N₂ proceeds during the thermal degradation of both ceramics. Additionally, the phase reaction Si₃N₄=3Si+2N₂ occurs during the thermal degradation of the NCP200 ceramic. To explain quantitatively the high temperature behaviour of Si–C–N ceramics, thermodynamic functions, the reaction scheme, isothermal sections, isopleths, phase fraction diagrams and phase composition diagrams (for gas partial pressures) were calculated. The computer simulations were confirmed by the experiments for both ceramics.