Interlocking editorship. A network analysis of the links between economic journals

The exploratory analysis developed in this paper relies on the hypothesis that each editor possesses some power in the definition of the editorial policy of her journal. Consequently if the same scholar sits on the board of editors of two journals, those journals could have some common elements in their editorial policies. The proximity of the editorial policies of two scientific journals can be assessed by the number of common editors sitting on their boards. A database of all editors of ECONLIT journals is used. The structure of the network generated by interlocking editorship is explored by applying the instruments of network analysis. Evidence has been found of a compact network containing different components. This is interpreted as the result of a plurality of perspectives about the appropriate methods for the investigation of problems and the construction of theories within the domain of economics.     

Sustainable simultaneous communications in ad-hoc networks using smart antenna systems

This article proposes an analytical model for evaluating the number of simultaneous communications that can be sustained by an ad-hoc network in which the nodes are equipped with fully adaptive smart antennas. The presented mathematical framework adopts realistic models for the antenna radiation pattern and the channel behavior, and is able to take into account the network topology and the characteristics of the medium access control (MAC) protocol in the spatial domain. The model is employed to investigate the impact of the spatial channel model and of the angular spread on network performance. Additionally, this article examines the influence of the transmission policy of the control and data packets of the MAC layer on the number of simultaneous communications.     

Thermal behaviour assessment of a novel vertical greenery module system: first results of a long-term monitoring campaign in an outdoor test cell

Vertical greenery modular systems (VGMSs) are an increasingly widespread building envelope solution aimed at improving the aesthetical quality of both new and existing façades, contemporarily achieving high energy efficiency performance. Within a research project, a new prototype of VGMS was developed, designed and tested. An experimental monitoring campaign was carried out on a test cell located in Turin (northern Italy), aimed at assessing both biometric parameters and energy-related issues. Two different types of growing media and two plant species, Lonicera nitida L. and Bergenia cordifolia L., have been tested on a south-facing lightweight wall. Results have been compared to the same wall without VGMS and plaster finished, in order to characterise the thermal insulation effectiveness in the winter period and the heat gain reduction in the summer period. Measured equivalent thermal transmittance values of the green modular system showed a 40 % reduction, when compared to the plastered wall, thus noticeably impacting on the energy crossing the façade during the heating season. Benefits of the VGMS are measured also during the summer season, when the presence of vegetation lowers the outdoor surface temperatures of the wall up to 23 °C compared to the plastered finishing, with a positive effect on outdoor comfort and urban heat island mitigation. Nevertheless, as far as the entering energies are concerned, not significant reduction was observed for VGMS, compared to the reference plastered wall, since the green coverage acts as a thermal buffer and solar radiation is stored and slowly released to the indoor environment.     

F-substituted hydroxyapatite nanopowders: Thermal stability,sintering behaviour and mechanical properties

Fluorine-substituted hydroxyapatites are considered promising materials for bone scaffolding. In this study a systematic investigation on F-half substituted hydroxyapatite (F-HAp, Ca₁₀(PO₄)₆OHF) obtained by precipitation is reported. Results on composition analysis, thermal behaviour, and sinterability are presented for a comparison with the respective pure hydroxyapatite. Samples were characterised by electron microscopy, induced coupled plasma-atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N₂ adsorption measurements, X-ray diffraction and dilatometry. A semicrystalline F-substituted hydroxyapatite powder made up of needle-like nanoparticles was obtained. Notwithstanding that it was thermally stable up to 1300 °C, it was sintered at relatively low temperatures obtaining a very fine microstructure with a relevant nano-porosity, beneficial in view of cell adhesion and in-growth.Hardness, elastic modulus and toughness of produced samples were investigated by Vickers–Knoop microhardness testing. Significant improvements of the mechanical properties were observed for the F-substituted hydroxyapatite, in comparison with pure hydroxyapatite.     

Be radioactive beam production at CIRCE and its utilization in basic and applied physics

A pure ⁷Be beam with an energy E = 1-8 MeV is available for nuclear and applied physics at the 3 MV Pelletron tandem accelerator CIRCE in Caserta. The beam is produced using an offline technique. Typical analyzed beam intensities are about 2 ppA, using cathodes with an activity of the order of 200 MBq. The ⁷Be implantation has been used for both fundamental nuclear physics and applied physics. In particular, different metals have been implanted with ⁷Be in order to study the influence of the chemical composition and of the number of quasi-free electrons of the host material on the ⁷Be half-life. In the field of applied physics, the ⁷Be implantation turns out to be very interesting for wear measurement. In fact, in this case ⁷Be is used as a depth-sensitive tracer. The continuous detection of the sample activity during the wear allows a high sensitivity measurement of wearing speed. The ⁷Be beam production at CIRCE, the implantation procedure and the results obtained from the ⁷Be half-life measurements and the wear characterization of implanted steel samples are described.     

Feedback controllability assessment and control of particle size distribution in emulsion polymerisation

In this article, the importance of particle size distribution (PSD) control as a means for the inferential control of the rheology of emulsion polymers is illustrated. A controllability assessment is presented to illustrate the attainability or otherwise of bimodal PSD using feedback control through a consideration of the process mechanisms—measurement limitations and process constraints that prevent the implementation of feedback corrections. The suitability of a batch-to-batch iterative feedback PSD control is demonstrated, which could act in addition to any in-batch feedback control, the latter being less feasible in certain cases, as argued in this article. A detailed population balance model is used for the batch-to-batch control, which simplifies model update and feedback correction.     

Robust estimators under semi‐parametric partly linear autoregression: Asymptotic behaviour and bandwidth selection

Abstract. In this article, under a semi‐parametric partly linear autoregression model, a family of robust estimators for the autoregression parameter and the autoregression function is studied. The proposed estimators are based on a three‐step procedure, in which robust regression estimators and robust smoothing techniques are combined. Asymptotic results on the autoregression estimators are derived. Besides combining robust procedures with M‐smoothers, predicted values for the series and detection residuals, which allow to detect anomalous data, are introduced. Robust cross‐validation methods to select the smoothing parameter are presented as an alternative to the classical ones, which are sensitive to outlying observations. A Monte Carlo study is conducted to compare the performance of the proposed criteria. Finally, the asymptotic distribution of the autoregression parameter estimator is stated uniformly over the smoothing parameter.     

Flexible joints control: A minimum-time feed-forward technique

The paper proposes a linear programming approach to the feed-forward minimum-time control of flexible joints. Taking into account both input and output constraints, the optimal bang–bang control is computed by discretizing a continuous-time joint model and by solving a sequence of linear programming feasibility problems. The resulting joint motion is a smooth rest-to-rest motion without oscillations. Theoretical analysis is presented and proof of convergence is given. Experimental results illustrate the proposed open-loop technique. Comparisons are made with inversion-based techniques.     

Direct electrochemical reduction of spinach and desulfovibrio desulfuricans Norway ferredoxins

Electrochemical techniques were used to study the reduction-reoxidation of spinach and Desulfovibrio desulfuricans ferredoxins in the presence of poly- -lysine. A peak corresponding to the reduction of native molecules was detected by differential pulse polarography and voltammetry at the basal-plane pyrolytic graphite electrode. The existence of reduction-reoxidation process was evidenced by cyclic voltammetry. The redox potential values of −0.42±0.01 V (spinach ferredoxin), −0.37±0.01 V (D. desulfuricans ferredoxin I), −0.41±0.01 V (D. desulfuricans ferredoxin II) were obtained. No changes in redox potential values were detected in the pH range 5–9.5. The presence of poly- -lysine promotes the electron transfer between the electrode and the ferredoxin molecules. It is suggested that several factors such as electrostatic interactions and the close environment of clusters can influence the electron transfer rates of heterogeneous exchange between the electrode and the ferredoxin molecules.