Direct utilization of methanol in solid oxide fuel cells: An electrochemical and catalytic study

This study deals with an investigation of the direct methanol oxidation in Solid Oxide Fuel Cells (SOFCs). A new catalyst formulation characterized by mixed electronic - ionic conductivity was developed for the anodic process. A composite Ni-modified La_0.6Sr_0.4Fe_0.8Co_0.2O₃-Ce_0.9Gd_0.1O₂ electrocatalyst was prepared by incipient wetness and subsequent ball milling. The obtained composite material was calcined at 1100 °C for 2 h in static air. After thermal activation, Ni was mainly present as highly dispersed La₂NiO₄ particles on a La-depleted Sr(Fe_0.5Co_0.5)O_2.88 perovskite. The subsequent thermal reduction at 800 °C in hydrogen caused the occurrence of highly dispersed metallic Ni on the electrocatalyst surface. The surface area of the composite material was determined by BET measurement. The reduced catalyst was used as anode in intermediate temperature Solid Oxide Fuel Cells (IT-SOFCs) directly fed with methanol. Ex-situ catalytic studies for the composite anode material under steam reforming, partial oxidation and autothermal reforming of methanol were carried out at 800 °C. A comparison of SOFC performance at 800 °C in the presence of syngas or methanol as fuels was carried out. The performance achieved for the direct utilization of methanol (350 mW cm⁻²) appears promising for SOFC application in remote and micro-distributed energy generation as well as for portable power sources.     

A Petri net based protection monitoring system for distribution networks with distributed generation

Connection of distributed generation (DG) essentially changes distribution network operation and creates a range of well-documented effects varying voltage levels and short circuit currents. Among others, DG can alter protection system operations in distribution networks, leading to failure of reclosing, disconnection of healthy feeder or prevention of protection operation. This paper proposes a procedure, based on Petri nets and supported by a centralized monitoring architecture for monitoring failures of the protection systems in radial distribution networks. Some case studies applied to a real Italian distribution network proved the effectiveness of the proposed procedure that can therefore represent an effective solution to improve distribution systems reliability in presence of DG.     

Fatty acid composition of certified organic,conventional and omega-3 eggs

The objective of this study was to compare the fatty acid composition of commercially available conventional, certified organic, and omega-3 eggs. Egg components were assessed, and the fatty acid composition of yolk lipids was determined by gas chromatography. Organic egg yolk contained a higher percentage of palmitic and stearic acids than did conventional yolk (P < 0.05) with no differences observed in the monounsaturated or polyunsaturated fatty acid compositions. Compared with organic and conventional eggs, omega-3 egg yolk contained lower percentages of myristic and palmitic acids, and higher omega-3 fatty acids. In a sub-analysis of conventional egg types, the percent of stearic acid in “cage” egg yolk was significantly lower (P < 0.05) than those of “barn-laid” and “free-range” eggs. “Cage” eggs had a significantly lower percentage (P < 0.05) of arachidonic acid than had “barn-laid” eggs. Consumption of omega-3 eggs has the potential to confer health benefits through the increase in intake of omega-3 fatty acids. With regard to organic or conventional methods of production, the small differences in saturated fatty acids observed in the present study are unlikely to have any significant metabolic effect on the consumer.     

Market research for requirements analysis using linguistic tools

Numerous studies in recent months have proposed the use of linguistic instruments to support requirements analysis. There are two main reasons for this: (i) the progress made in natural language processing and (ii) the need to provide the developers of software systems with support in the early phases of requirements definition and conceptual modelling. This paper presents the results of an online market research intended (a) to assess the economic advantages of developing a CASE (computer-aided software engineering) tool that integrates linguistic analysis techniques for documents written in natural language, and (b) to verify the existence of the potential demand for such a tool. The research included a study of the language – ranging from completely natural to highly restricted – used in documents available for requirements analysis, an important factor given that on a technological level there is a trade-off between the language used and the performance of the linguistic instruments. To determine the potential demand for such tool, some of the survey questions dealt with the adoption of development methodologies and consequently with models and support tools; other questions referred to activities deemed critical by the companies involved. Through statistical correspondence analysis of the responses, we were able to outline two profiles of companies that correspond to two potential market niches, which are characterised by their very different approach to software development.

Interaction of interface delamination and plasticity in tensile steel members reinforced by CFRP plates

This paper presents experimental and numerical results related to double shear lap tests performed on steel specimens reinforced using CFRP plates. These tests have been simulated taking into account the elastic–plastic behavior of the steel and the delamination between steel and CFRP by means of a cohesive approach. The results obtained are discussed in terms of: (i) maximum load bearing capacity, (ii) minimum bond length in order to exploit the maximum load bearing capacity, (iii) brittle to ductile transition of the interface failure (iv) combination of interface delamination and plastic deformation of the steel. Design formulas for the definition of the minimum bond length and the load bearing capacity of the joint are validated.     

Reinforcement delamination of metallic beams strengthened by FRP strips: Fracture mechanics based approach

The delamination failure of metallic beams reinforced by externally bonded fibres reinforced polymers (FRP) is addressed in this paper and a simplified fracture mechanics based approach for the edge delamination of the reinforcement strips is illustrated. The criterion is based on the evaluation of the energy release rate (ERR) using both analytical and numerical models. The analytical models consist of a simplified version of a “two parameters elastic foundation” and “transformed section” model while the numerical analyses refer to the modified virtual crack closure technique (MVCCT). The main aim of the paper is to establish a fracture mechanics failure criterion based on the ERR and the specific fracture energy of the bonded strips. The criterion is an alternative approach to the well known stress based method to asses the load carrying capacity of the adhesive joint. The accuracy of the simplified approaches is shown through a numerical example which refers to a steel beam strengthened by carbon fibres reinforced polymers (CFRP).     

On-line hollow-fiber flow field-flow fractionation-electrospray ionization/time-of-flight mass spectrometry of intact proteins

Capabilities of mass spectrometry for the analysis of intact proteins can be increased through separation methods. Flow field-flow fractionation (FlFFF) is characterized by the particularly "soft" separation mechanism, which is ideally suited to maintain the native structure of intact proteins. This work describes the original on-line coupling between hollow-fiber FlFFF (HF FlFFF), the microcolumn variant of FlFFF, and electrospray ionization/time-of-flight mass spectrometry (ESI/TOFMS) for the analysis and characterization of intact proteins. The results show that the native (or pseudonative) structure of horse heart myoglobin and horseradish peroxidase is maintained. Sample desalting is also observed for horse heart myoglobin. Correlation between the molar mass values independently measured by HF FlFFF retention and ESI/TOFMS allows us to confirm the protein aggregation features of bovine serum albumin and to indicate possible changes in the quaternary structure of human hemoglobin.     

Mechanical refrigeration using an ejector-injector to transfer the working fluid from the evaporator to the condenser

The refrigeration plant described in this paper uses an ejector-injector instead of a compressor to pump the freezing mixture from the evaporator to the condenser. A pump draws the liquid from the condenser and pumps it to another vessel. Before the ejector-injector, a heat exchanger preheats the refrigerating fluid to speed up the mixing with steam ejected from the evaporator. The steam is compressed using kinetic energy in the ejector-injector and the pump supplies a discharge pressure to operate the plant. The heat transfer fluid, the condensing and evaporating pressures and the energy losses determine the operating features of the plant. Energy saving is obtained using such an ejector-injector and it provides a simple method of refrigeration. The operating conditions were optimized in this study and the feasibility of the plant was confirmed.     

P systems with symport/antiport simulating counter automata

The generative capability of several variants of P systems with symport/antiport is studied via the simulation of counter automata. This leads to the reduction of the complexity, expressed in number of membranes and weight of rules, of P systems generating recursively enumerable sets.Received: 4 December 2003, Published online: 3 November 2004     

Normalization techniques for the SVE of the Green function of Helmholtz operator

Electromagnetic and acoustic scattering problems can be usually formulated by suitable integral equations, where the kernel is given in terms of the fundamental solution of the Helmholtz operator. We can consider a special analytic method for the singular value expansion (SVE) of this integral kernel. Note that this is an important tool for the numerical solution of scattering problems, in fact, from the knowledge of the SVE of the integral kernel, we can easily solve the corresponding integral equation. In this paper, we study the numerical approximation of the SVE of this integral kernel, where we have to consider the asymptotic behavior of the Bessel functions.