Novel link adaptation for TETRA cellular systems

One of the main challenges for future wireless systems is to enhance the effective data throughput by exploiting the allocated bandwidth as much as possible. Among several approaches at different layers, one of the most important is constituted by the so‐called link adaptation (LA) techniques. They are characterized by the adaptation of a set of transmission parameters to the channel state in order to improve performance. In this context, this paper is focused on the analysis of a particular class of LA techniques called adaptive modulation and coding, where the modulation and coding rate of transmission can vary according to the channel behavior. In particular, a novel LA algorithm, namely the timed window (TW) method, suitable for time‐division Duplex systems is proposed here. The performance of the TW algorithm is evaluated by taking actual user mobility conditions, communication channel behavior, as well as the physical layer effects into account. Finally, it is important to stress that, even if the wireless bearer considered in this study is TETRA (TErrestrial Trunked RAdio), the approach is quite general and it can be of interest for other wireless networks and can be optimized for different channel models (e.g. TU50, HT200, etc.). Copyright © 2008 John Wiley & Sons, Ltd.     

Theoretical study and performance evaluation of hydrogen production by 200 W solid oxide electrolyzer stack

High temperature steam electrolyzers, taking advantage of high temperature heat, can produce more hydrogen by using less electrical energy than low temperature electrolyzers. This paper presents an experimental study on hydrogen production by using a 200 W solid oxide stack working in reverse mode. A thermodynamic study of the process was performed by measuring the heat and mass balance of stack at different operating conditions. Different definitions of efficiency were used to highlight the limit and potential of the process. The I–V curve, the flow rate measurements and the GC analysis on outlet flows were used to calculate the hydrogen and oxygen productions. In addition, the influence of steam dilution, water utilization and operating temperature on conversion efficiency and stack's thermal balance was evaluated. With this aim, the tests were performed at three operating temperature (700 °C, 750 °C and 800 °C) over a range of steam inlet concentration from 50% to 90% and water utilization up to 70%. The hydrogen and oxygen flows produced by electrolysis, at different loads, were directly measured after water condensation: net flows up to 2.4 ml/(min cm²) of hydrogen and 1.2 ml/(min cm²) of oxygen were measured and compared to the theoretical ones, showing a good agreement.     

Combined Effects of Parallel and Series Detention Basins for Flood Peak Reduction

A simple analytical method is proposed that allows a preliminary evaluation of the overall efficiency of a detention basin system for flood risk reduction in a specific target section. Solutions are provided both for parallel and series systems, under some simplifying assumptions concerning the linearity of detention basin, river network and watershed responses. Further, for the series configuration a regressive model is proposed for the computation of the overall efficiency, because of the complexity of analytical solution. A case study is also presented, where the overall efficiency of a system of nine detention basins is computed by means of both the analytical and the regressive model. Results are discussed to assess the different influence of detention basins in parallel or in a series system.     

Pulsed laser deposition of organic and biological materials

We report on the deposition of soft matter thin films by Matrix Assisted Pulsed Laser Evaporation (MAPLE). In particular, thin layers of biological material (Bovine Serum Albumin) and polymers (polyfluorene) for medical and optoelectronic applications, were realized by laser irradiating a frozen solution containing a low amount of material diluted in a laser absorbing volatile solvent. The depositions were carried out varying different parameters as solvent–solute concentration, solvent nature, laser fluencies, etc. The optical, morphological, structural and spectroscopical properties were detected by means of different analyses as FTIR, photoluminescence, AFM and SDS.     

Gold nanoparticles induce cytotoxicity in the alveolar type-II cell lines A549 and NCIH441

Background  

During the last years engineered nanoparticles (NPs) have been extensively used in different technologies and consequently many questions have arisen about the risk and the impact on human health following exposure to nanoparticles. Nevertheless, at present knowledge about the cytotoxicity induced by NPs is still largely incomplete. In this context, we have investigated the cytotoxicity induced by gold nanoparticles (AuNPs), which differed in size and purification grade (presence or absence of sodium citrate residues on the particle surface) in vitro, in the human alveolar type-II (ATII)-like cell lines A549 and NCIH441.     

Landscape dynamics of Mediterranean montane grasslands over 60 years and implications for habitats conservation. A case study in the northern Apennines (Italy)

Widespread trends of abandonment have strongly affected Mediterranean mountains after the Second World War, triggering spontaneous recolonisation of forests. A diachronic analysis of the landscape in a Natura 2000 site (Tuscany, Italy) was carried out using digital aerial photographs (1954, 2013) and a GIS-based methodology, focusing on territories above 1300 m a.s.l. The detected variations of total areas, patch shape, patch dimensions and selected metrics showed a notable shift of the vegetation towards woody types and a drastic reduction of open grasslands, some with high conservation value, accompanied by a strong increase in patch number, surface and edge. A decrease of SDI and SEI diversity indices was also observed. Considering that fragmentation is one of the main causes threatening habitats and species, our results point out a clear necessity for a monitoring programme and suitable actions aimed at improving the status of biodiversity-rich montane grasslands.     

Fitting genetic algorithms to distributed on-line evolution of network protocols

In this work, we introduce a framework for enabling the on-line evolution of network protocols. The proposed approach is based on the use of techniques and tools drawn from evolutionary computing research, and it enables embedding evolutionary features in the operation of network protocols. In this way, it becomes possible to build a system in which the operation of the network changes at run-time to adapt to the current conditions. As a case study, we apply the proposed framework to the evolution of forwarding schemes in intermittently connected wireless networks. Simulation results are reported to validate the ability of the proposed scheme to converge to the optimal operating point and to explore the various trade-offs deriving from its design and implementation.