Direct utilization of methanol on impregnated Ni/YSZ and Ni-Zr0.35Ce0.65O2/YSZ anodes for solid oxide fuel cells

Some of the limits on fuel cell development include the issues of hydrogen availability and storage. Methanol has many advantages as an alternative fuel for fuel cells but depending on the anode composition, the formation of carbon may be a problem. In this paper, the direct utilization of methanol in solid oxide fuel cells with impregnated Ni/YSZ and Ni-Zr_0.35Ce_0.65O_2−δ (ZDC)/YSZ anodes was investigated at 1073 K. Performance and stability of these anodes, as measured by steady-state polarization and electrochemical impedance spectroscopy, were improved by the presence of ZDC; although, the deposition of carbon, as detected by scanning electron microscopy and temperature-programmed oxidation analysis, was not entirely avoided. The impact of the carbon, however, was different depending on the anode. That is, carbon formation caused the delamination of impregnated Ni/YSZ anodes, while the structural integrity of Ni-ZDC/YSZ anodes was maintained and the cell performance was not negatively impacted. Increasing the fuel utilization decreased coking, as predicted by equilibrium calculations.     

Performance and robustness of block constraint preconditioners in finite element coupled consolidation problems

Block constraint preconditioners are a most recent development for the iterative solution to large‐scale, often ill‐conditioned, coupled consolidation problems. A major limitation to their practical use, however, is the somewhat difficult selection of a number of user‐defined parameters (at least 4) in a more or less optimal way. The present paper investigates the robustness of three variants of the block constraint preconditioning in relation to the above parameters. A theoretical analysis of the eigenspectrum of the preconditioned matrix provides relatively simple bounds of the eigenvalues as a function of these parameters. A number of test problems used to validate the theoretical results show that both the mixed constraint preconditioner (MCP) combined with the symmetric quasi‐minimal residual (SQMR) solver and the MCP triangular variant (T‐MCP) combined with the bi‐conjugate gradient stabilized (Bi‐CGSTAB) are efficient and robust tools for the solution to difficult Finite Element‐discretized coupled consolidation problems. Moreover, the practical selection of the user‐defined parameters is relatively easy as a stable behavior is observed for a wide range of fill‐in degree values. The theoretical bounds on the eigenspectrum of the preconditioned matrix may help to suggest the most appropriate parameter combination. Copyright © 2009 John Wiley & Sons, Ltd.     

Direct utilization of methanol and ethanol in solid oxide fuel cells using Cu-Co(Ru)/Zr0.35Ce0.65O2−δ anodes

The direct utilization of methanol (MeOH) and ethanol (EtOH) was investigated on Cu-Co(Ru)/Zr_0.35Ce_0.65O₂ anodes for solid oxide fuel cells (SOFC) prepared by impregnation. Cells had similar performance and stability in H₂ and MeOH, while in EtOH the performance varied with time; that is, the power density initially increased, and then declined exponentially. This behavior was likely a consequence of carbon deposition that initially improved electronic conductivity to the anode functional layer, and subsequently blocked active sites. For all cells, the performance was recovered by re-exposing the anode to humidified hydrogen. In some cases, the cell performance exceeded the initial activity measured in hydrogen. Thus, the direct utilization of MeOH and EtOH did not irreversibly deactivate the Co(Ru)/Zr_0.35Ce_0.65O₂ anodes.     

Reforming of olive mill wastewater through a Pd-membrane reactor

This work investigates the exploitation of olive mill wastewater (OMW) for producing hydrogen in a membrane reformer.     

Photochromic Polymers Based on the Photoinduced Opening and Thermal Closing of [1,3]Oxazine Rings

Two macromolecular constructs incorporating a single polymer backbone with multiple photochromic side chains are developed. Both systems are prepared from preformed photochromic [1,3]oxazines after the ring‐opening polymerization of their norbornene appendages. In solution, UV illumination of these polymers opens the [1,3]oxazine rings in their side chains in less than 6 ns and with a quantum yield of 0.09 in both instances. The photogenerated species incorporate a 4‐nitrophenolate chromophore, and hence, their formation is accompanied by the appearance of an intense band in the visible region of the absorption spectrum. The photoproducts revert spontaneously to the original state with first‐order kinetics in microseconds. Furthermore, both photochromic polymers tolerate hundreds of switching cycles with no sign of degradation, even in the presence of molecular oxygen. Thus, this design logic and choice of functional building blocks can translate into the realization of innovative photoresponsive materials with excellent photochromic performance.     

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.     

Temperature and storage effects on antioxidant activity of juice from red and white grapes

The effect of temperature and storage time on the phenolic composition and on the antioxidant activity of grape (Vitis vinifera L.) juices made using a red (Sangiovese, SG) and a white (Muscat of Alexandria, MA) variety was studied. Total phenolics, flavonoids, flavan‐3‐ols and hydroxycinnamoyl‐tartrates (HCT) were determined on grape extracts (GE) and juices. Total anthocyanins and anthocyanins composition were measured on GE. The antioxidant activity was assessed by means of two different in vitro tests: scavenging of the stable 2,2‐diphenyl‐1‐picrylhydrazyl radical and the inhibition of tyrosine nitration mediated by authentic peroxynitrite (ONOO^?). All the juices were analysed after 24 h and 2 weeks of storage by means of two‐way anova (factors being cultivar and temperature). Anthocyanins were not detected in MA extract, whereas in SG their content was 534 mg malvidin‐equivalent per 100 g of dry matter (d.m.) and malvidin derivatives (glycosylated and coumaroylated) were the most represented (respectively 169 and 41 malvidin‐equivalent per 100 g of d.m.). HCT content of the extracts was higher in SG (overall +33%). Also in grape juices, HCT were lower in MA and in this variety, the trans‐fertaric and cis‐coutaric acids were also undetectable. Cultivar effect proved to be highly significant, while no significant differences in the phenolic composition were observed for storage temperatures (4 and ?20 °C) and cultivar × temperature interaction. However, when statistical analysis was focused on each cultivar, MA was found to be more sensible to storage conditions and a significant reduction in total phenolics (?20%) and flavonoids (?53%) content and in the ONOO^? scavenging potential (?32%) was evident after 2 weeks at 4 °C (when compared with the same storage temperature after 24 h). On the contrary, SG juices did not show significant differences among the four storage treatments investigated. These results could be explained suggesting that anthocyanins presence in red grape plays a key role in juice stability.     

Optimal selection of soft sensor inputs for batch distillation columns using principal component analysis

In this paper, a novel methodology based on principal component analysis (PCA) is proposed to select the most suitable secondary process variables to be used as soft sensor inputs. In the proposed approach, a matrix is defined that measures the instantaneous sensitivity of each secondary variable to the primary variables to be estimated. The most sensitive secondary variables are then extracted from this matrix by exploiting the properties of PCA, and they are used as input variables for the development of a regression model suitable for on-line implementation.This method has been evaluated by developing a soft sensor that uses temperature measurements and a process regression model to estimate on-line the product compositions for a simulated batch distillation process. The identification of the optimal soft sensor inputs for this case study has been discussed with respect to the definition of the sensitivity matrix, the data sampling interval, the presence of measurement noise, and the size of the input set. The simulation results demonstrate that the proposed approach can effectively identify the size and configuration of the input set that leads to the optimal estimation performance of the soft sensor.     

Using 3D Sound to Improve the Effectiveness of the Advanced Driver Assistance Systems

Future generation cars will be characterized by a wide range of Information Technology (IT) services providing safety and infotainment. This makes the car an information intensive environment where the visual channel is overloaded, putting the safety of drivers and passengers in jeopardy. We propose the use of a 3D auditory display to provide information from the Advanced Driver Assistance Systems. This reduces the eye-off-road time, exploiting the human capability to associate sounds with positions in space. Preliminary lab tests reveal the suitability of this approach. The system still has to be carefully tuned and personalized to achieve usability and reliability, but we think that it provides a complementary channel that is specially useful in low visibility conditions.