A wideband two-layer radio access network using DECT technology inthe uplink

This article describes a novel architecture of a broadband radio access network using the two-layer network solution. The proposed downlink is compliant with the DVB-S standards, and a DECT custom solution is used in the return channel. The idea we present is based on the use of a “single carrier with equalization” system in order to directly link the end-user terminal, avoiding the most expensive part of the cabling network: the last mile. The article reports, some considerations concerning the advantages and disadvantages of the novel architecture. Successively, aspects such as frequency plan, architecture of the base station, local repeater, and user terminal, in combination with some practical studies, are discussed     

Cogeneration plant in a pasta factory: Energy saving and environmental benefit

Italy produces approximately 4,520,000 tons of pasta annually, which is about 67% of its total productive potential. As factories need electric and thermal energy simultaneously, combined heat and power (CHP) systems are the most suitable. This paper describes a feasibility study of a CHP plant in a pasta factory in Italy while analyzing energy saving and environmental benefits. Commercially available CHP systems suitable for the power range of energy demand in pasta production use reciprocating engines or gas turbines. This study demonstrates how their use can reduce both energy costs and CO₂ equivalent greenhouse gas emission in the environment. An economic analysis was performed following the methodology set out by Italian National Agency for Technology, Energy and Environment (ENEA) based on a discounted cash flow (DCF) method called “Valore Attuale Netto” (VAN), which uses a cash flow based on the saving of energy when using different energy processes.     

Inherently fluorescent polyaniline nanoparticles in a dynamic landscape

In this paper we report for the first time on the emissive behavior of two polyaniline (PANI) nanoparticle systems produced via oxidative chemical polymerization in the presence of either poly(vinyl alcohol) (PVA) or chitosan as polymeric stabilizers in water. The emission from PANI nanoparticles is irreversibly quenched by an increase of pH of the suspending medium from acid to neutral (chitosan-PANI) or alkaline (PVA-PANI). Conversely, PANI nanorods synthesized in the same conditions of the above, but in presence of poly(N-vinyl pyrrolidone), is not emissive at any pH. The role of the polymeric surfactant as a soft template is key in controlling the morphology and the properties of the obtained PANI dispersions. FTIR, UV-Vis absorption and photoluminescence excitation (PLE) spectra studies suggest that the emissive properties are related to the establishment of strong, non-covalent interactions between nanoscalar PANI particles and the polymeric surfactant at the pH of synthesis. Morphology examination of the three systems, by both dynamic light scattering (DLS) and Transmission Electron Microscopy (TEM), reveal that photoluminescence is associated to the presence of a genuinely 3D nanoscalar morphology, together with an ordered disposition of PANI chains into aligned crystal planes. Concomitant to the irreversible quenching of the emission signal with increasing pH, there is an evolution of the morphology leading to particle coalescence, coarsening and ultimately phase-separation, with consequent modification of PANI-polymeric surfactant interactions, PANI chains supra-molecular organization and optical properties of the PANI nanoparticles dispersion.     

Exergy recovery in regasification facilities – Cold utilization: A modular unit

The paper deals with the problem of cold recovery for direct utilization both in the site of regasification facility and far from it.A modular LNG regasification unit is proposed having the regasification capacity of 2 billion standard cubic meters/year of gas. The modular plant is based on use of a power cycle working with ethane or ethylene which allows operation of cold energy transfer, contained in LNG to be regasified, in a range of temperatures suitable for multipurpose use of cold, reducing regasification process irreversibility. Some electric energy is produced by the power cycle, but the own mission of modular unit proposed is addressed to deliver cold suitable for industrial and commercial use in the proper temperature range. The option considers, also, the use of carbon dioxide as a secondary fluid for transfer of cold from regasification site to far end users. This option seems very attractive due to expected wide future exploitation of LNG regasification in the world.Results of a detailed thermodynamic and economic analysis demonstrate the suitability of the proposal.     

Exergy recovery during LNG regasification: Electric energy production – Part one

In LNG regasification facilities, for exergy recovery during regasification, an option could be the production of electric energy recovering the energy available as cold. The authors propose an innovative process which uses a cryogenic stream of LNG during regasification as a cold source in an improved CHP plant (combined heat and power). Considering the LNG regasification projects in progress all over the World, an appropriate design option could be based on a modular unit having a mean regasification capacity of 2 × 10⁹ standard m³/yr.This paper deals with an outlook of LNG trading now expanding in the World and gives a concise state of the art with a review of technology seeming that proposed. Then an innovative CHP plant and results pertaining the selection of working fluids, made with an optimization analysis, are presented.     

Exergy recovery during LNG regasification: Electric energy production – Part two

In liquefied natural gas (LNG) regasification facilities, for exergy recovery during regasification, an option could be the production of electric energy recovering the energy available as cold. In a previous paper, the authors propose an innovative process which uses a cryogenic stream of LNG during regasification as a cold source in an improved combined heat and power (CHP) plant. Considering the LNG regasification projects in progress all over the World, an appropriate design option could be based on a modular unit having a mean regasification capacity of 2 × 10⁹ standard cubic meters/year.This paper deals with the results of feasibility studies, developed by the authors at DREAM in the context of a research program, on ventures based on thermodynamic and economic analysis of improved CHP cycles and related innovative technology which demonstrate the suitability of the proposal.     

High Temperature Operation of a Solid Polymer Electrolyte Fuel Cell Stack Based on a New Ionomer Membrane

Polymer electrolyte fuel cell stacks assembled with Johnson Matthey Fuel Cells and SolviCore MEAs based on the Aquivion™ E79‐03S short‐side chain (SSC), chemically stabilised perfluorosulphonic acid membrane developed by Solvay Solexis were investigated at CNR‐ITAE in the EU Sixth Framework ‘Autobrane' project. Electrochemical experiments in fuel cell short stacks were performed under practical automotive operating conditions at pressures of 1–1.5 bar abs. over a wide temperature range, up to 130 °C, with varying levels of humidity (down to 18% R. H.). The stacks using large area (360 cm²) MEAs showed elevated performance in the temperature range from ambient to 100 °C (cell power density in the range of 600–700 mWcm^–2) with a moderate decrease above 100 °C. The performances and electrical efficiencies achieved at 110 °C (cell power density of about 400 mWcm^–2 at an average cell voltage of about 0.5–0.6 V) are promising for automotive applications. Duty‐cycle and steady‐state galvanostatic experiments showed excellent stack stability for operation at high temperature. A performance comparison of Aquivion^TM and Nafion^TM‐based MEAs under practical operating conditions showed a significantly better capability for the Solvay Solexis membrane to sustain high temperature operation.     

Synthesis,characterisation and properties of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide-graft-maleic anhydride precursors and their stimuli-responsive hydrogels

A family of poly(amino acid)-maleic anhydride hydrogels were designed and synthesized. Water soluble polymeric precursors were prepared by partially substituting the hydroxyl groups of the α,β-poly(N-2-hydroxyethyl)-dl-aspartamide backbone with maleic anhydride, so as to provide double bonds for crosslinking and carboxylic acid groups for pH and electric field responsiveness. Reaction conditions (reactive mixture composition and catalysis) were systematically varied in order to obtain PHEA–MA precursors with different and reliable graft-maleic anhydride levels. PHEA–MA precursors were characterised by titration, Nuclear Magnetic Resonance (¹H NMR), Fourier-Transformed Infrared Spectroscopy (FTIR) and Size Exclusion Chromatography (SEC) for structural and molecular determination. Aqueous solutions of selected PHEA–MA precursors were subjected to gamma-irradiation at different irradiation doses and polymer to water concentrations in order to induce chemical crosslinking without the addition of crosslinking agents. The yield of crosslinking reactions was evaluated by solubility tests as well as the effect of ammonium persulphate, as assistant radical initiator for gamma crosslinking. Selected hydrogels were tested through swelling measurements to prove their pH and electric field responsiveness. Structural features of the different variants produced were related to the swelling behaviour.     

Reactive blending of functionalized acrylic rubbers and epoxy resins

A high molecular weight acrylonitrile/butadiene/methacrylic acid (Nipol 1472) rubber is chosen to control processability and mechanical properties of a TGDDM (tetra glycidyl diphenyl methane) based epoxy resin formulation for aerospace composite applications. The physical blend of rubber and epoxy resin, achieved by dissolution of all the components in a common solvent, forms a heterogeneous system after solvent removal and presents coarse phase separation during cure that impairs any practical relevance of this material. A marked improvement of rubberepoxy miscibility is achieved by reactive blending (‘pre‐reaction’) the epoxy oligomer with the functional groups present in the rubber. The epoxy‐rubber ‘adduct’ so obtained appears as a homogeneous system at room temperature and also after compounding with the curing agent. Depending on the nature and extent of interactions developed between the rubber and the epoxy resin during ‘pre‐reaction,’ materials with different resin flow characteristics, distinctive morphologies and mechanical properties after curing were obtained. The effect of ‘pre‐reaction’ on the resin cure reaction kinetics has been also investigated.