The d-index: Discovering dependences among scientific collaborators from their bibliographic data records

The evaluation of the work of a researcher and its impact on the research community has been deeply studied in literature through the definition of several measures, first among all the h-index and its variations. Although these measures represent valuable tools for analyzing researchers?? outputs, they usually assume the co-authorship to be a proportional collaboration between the parts, missing out their relationships and the relative scientific influences. In this work, we propose the d-index, a novel measure that estimates the dependence degree between authors on their research environment along their entire scientific publication history. We also present a web application that implements these ideas and provides a number of visualization tools for analyzing and comparing scientific dependences among all the scientists in the DBLP bibliographic database. Finally, relying on this web environment, we present case and user studies that highlight both the validity and the reliability of the proposed evaluation measure.     

Hydrogen production through anaerobic co-digestion of food waste and crude glycerol at mesophilic conditions

Hydrogen production from mesophilic anaerobic co-digestion of food waste (FW) and crude glycerol (GLC) was investigated in this study. Batch experiments were carried out at 35 °C for 36 h to assess the effect of supplementation of different glycerol concentrations (1%, 3% and 5% (v/v)) on dark fermentation of FW. The maximum hydrogen yield (180 mLH₂/gVS) was obtained at 5% GLC while the maximum specific production rate (around 13 mLH₂/(gVS.h)) was similar for all experiments with glycerol addition. Besides contributing to increase H₂ productivity, the presence of glycerol reduced the microorganisms acclimation time (Lag phase) in comparison to the control tests conducted without this co-substrate. In addition, the increment of glycerol concentration also enhanced volatile fatty acids generation and favoured the production of 1,3-propanediol (1,3-PDO). In the experimental conditions studied (i.e., 1–5% (v/v) of GLC), the results revealed that co-digestion of FW and GLC is promising and can be potentially used to maximize energy production while contributing to the management and treatment of these wastes.     

Vinylene-linked pyridine-pyrrole donor–acceptor conjugated polymers

Vinylene-linked donor–acceptor–donor semiconducting polymers have been prepared by electropolymerization of the new monomers 2,6-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine and 2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine. The monomers, consisting of two pyrrole donor units and a central pyridine acceptor ring spaced by vinylene links, differ by the substitution pattern around the central pyridine core (2,6 vs. 2,5-substitution). The electropolymerization process is more efficient on the 2,5-derivative. The new polymers show reversible electrochemistry dominated by a strong charge trapping effect. Poly(2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine) energy levels closely match those of design rules for optimized polymers in combination with fullerene derivatives in bulk heterojunction solar cells.     

Software sensor for on-line estimation of the microbial activity in activated sludge systems

This paper considers the design of a software sensor (or soft-sensor) for the on-line estimation of the biological activities of a colony of aerobic micro-organisms acting on activated sludge processes, where the carbonaceous waste degradation and nitrification processes are taken into account. These bioactivities are intimately related to the dissolved oxygen concentration. Two factors that affect the dynamics of the dissolved oxygen are the respiration rate or the oxygen uptake rate (OUR) and the oxygen transfer function (K(l)a). These items are challenging topics for the application of recursive identification due the nonlinear characteristic of the oxygen transfer function, and to the time-varying feature of the respiration rate. In this work, OUR and the oxygen transfer function are estimated through a software sensor, which is based on a modified version of the discrete extended Kalman filter. Numerical simulations are carried out in a predenitrifying activated sludge process benchmark and the obtained results demonstrate the applicability and efficiency of the proposed methodology, which should provide a valuable tool to supervise and control activated sludge processes.     

Convergent optical correlator aligment based on frequency filtering

The convergent correlator is widely used but it presents the drawback of the alignment requirements: fine focusing of the input scene Fourier transform on the filter plane, filter centering, scaling the scene Fourier transform to match the filter size, and azimuth matching of the filter with the input scene. We propose a set of tests to obtain a precise alignment of the convergent correlator. These methods are based on frequency filtering properties and they are applicable either for amplitude input or for phase-encoded input. The tests we present allow us to fulfill all the alignment requirements. The theory on which these tests are based is explained. The experimental results obtained during the alignment procedure are presented. We show some additional verifications of the correct alignment of the convergent correlator.     

Neighborhood effects in reading aloud: New findings and new challenges for computational models.

A word from a dense neighborhood is often read aloud faster than a word from a sparse neighborhood. This advantage is usually attributed to orthography, but orthographic and phonological neighbors are typically confounded. Two experiments investigated the effect of neighborhood density on reading aloud when phonological density was varied while orthographic density was held constant, and vice versa. A phonological neighborhood effect was observed, but not an orthographic one. These results are inconsistent with the predominant role ascribed to orthographic neighbors in accounts of visual word recognition and reading aloud. Consistent with this interpretation, 6 different computational models of reading aloud failed to simulate this pattern of results. The results of the present experiments thus provide a new understanding of some of the processes underlying reading aloud, and new challenges for computational models. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Input-to-state stable finite horizon MPC for neutrally stable linear discrete-time systems with input constraints

MPC or model predictive control is representative of control methods which are able to handle inequality constraints. Closed-loop stability can therefore be ensured only locally in the presence of constraints of this type. However, if the system is neutrally stable, and if the constraints are imposed only on the input, global asymptotic stability can be obtained; until recently, use of infinite horizons was thought to be inevitable in this case. A globally stabilizing finite-horizon MPC has lately been suggested for neutrally stable continuous-time systems using a non-quadratic terminal cost which consists of cubic as well as quadratic functions of the state. The idea originates from the so-called small gain control, where the global stability is proven using a non-quadratic Lyapunov function. The newly developed finite-horizon MPC employs the same form of Lyapunov function as the terminal cost, thereby leading to global asymptotic stability. A discrete-time version of this finite-horizon MPC is presented here. Furthermore, it is proved that the closed-loop system resulting from the proposed MPC is ISS (Input-to-State Stable), provided that the external disturbance is sufficiently small. The proposed MPC algorithm is also coded using an SQP (Sequential Quadratic Programming) algorithm, and simulation results are given to show the effectiveness of the method.     

On the Generation of Sequential Unitary Gates from Continuous Time Schrödinger Equations Driven by External Fields

In most of the proposals for quantum computers, a common feature is that the quantum circuits are expected to be made of cascades of unitary transformations acting on the quantum states. Such unitary gates are normally assumed to belong to a given discrete set of transformations. However, arbitrary superposition of quantum states may be achieved by utilizing a fixed number of transformations, each depending on a parameter. A framework is proposed to dynamically express these parameters directly in terms of the control inputs entering into the continuous time forced Schrouml;dinger equation. PACS: 03.67.Lx; 03.65.Fd; 02.30.Mv; 02.30.Xy