Thermal Diffusivity Measurements in Edible Oils using Transient Thermal Lens

Time resolved thermal lens (TL) spectrometry is applied to the study of the thermal diffusivity of edible oils such as olive, and refined and thermally treated avocado oils. A two laser mismatched-mode experimental configuration was used, with a He–Ne laser as a probe beam and an Ar⁺ laser as the excitation one. The characteristic time constant of the transient thermal lens was obtained by fitting the experimental data to the theoretical expression for a transient thermal lens. The results showed that virgin olive oil has a higher thermal diffusivity than for refined and thermally treated avocado oils. This measured thermal property may contribute to a better understanding of the quality of edible oils, which is very important in the food industry. The thermal diffusivity results for virgin olive oil, obtained from this technique, agree with those reported in the literature.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5-8, 2005, Bratislava, Slovak Republic.     

Morphodynamic signatures derived from daily surface elevation dynamics can explain the morphodynamic development of tidal flats

Understanding the sensitivity of tidal flats to environmental changes is challenging. Currently, most studies rely on process-based models to systematically explain the morphodynamic evolution of tidal flats. In this study, we proposed an alternative empirical approach to explore tidal flat dynamics using statistical indices based on long-term time series of daily surface elevation development. Surface elevation dynamic (SED) indices focus on the magnitude and period of surface elevation changes, while morphodynamic signature (MDS) indices relate sediment dynamics to environmental drivers. The statistical analyses were applied to an intervention site in the Netherlands to determine the effect of recently constructed groynes on the tidal flat. Using these analyses, we were able to (1) detect a reduction in the daily SED and (2) determine that the changes in the daily SED were predominantly caused by the reduction in wave impact between the groynes rather than the reduction in tidal currents. Overall, the presented results showed that the combination of novel statistical indices provides new insights into the trajectories of tidal flats, ecosystem functioning, and sensitivity to physical drivers (wind and tides). Finally, we suggested how the SED and MDS indices may help to explore the future trajectories and climate resilience of intertidal habitats.     

系统级可编程能力助力嵌入式应用

本文探讨了人们通常面对的嵌入设计挑战.并以实用的方式探讨如何运用PSoC芯片这种系统级的可编程能力克服这些挑战.     

Mechanical design of a 3-stage ADR for the Astro-H mission

The X-ray micro-calorimeter array in the Soft X-ray Spectrometer (SXS) instrument on Astro-H will be cooled by a 3-stage adiabatic demagnetization refrigerator (ADR). The ADR consists of two mechanically independent assemblies. When integrated with a mounting structure and the detector assembly, they form a self-contained unit that will be inserted into the top end of a liquid helium tank. The unique configuration requires many components and sub-assemblies to be thermally isolated from their structural mount. Normally in an ADR this is limited to suspending cold salt pills within their (much warmer) magnets, but in the case of SXS, it also involves one ADR stage being supported by, but thermally isolated from, the helium tank. This paper will describe the complex thermal and mechanical design of the SXS ADR, and summarize vibration and mechanical properties tests that have been performed to validate the design.     

Evolution of esters in aged Chardonnay wines obtained with different vinification methods

BACKGROUND: During wine ageing on lees yeast lysis takes place and some enzymes from the yeast cells, such as esterases, may be released. These enzymes might determine ester synthesis and could be also involved in their breakdown. In this study, the evolution of esters in Chardonnay wine fermented in stainless steel tanks and aged in bottles (conventional vinification) was compared with the evolution of esters in the same wine fermented and aged in barrel on lees. In this way, it was hoped to determine the influence of distinct methods of vinification on the evolution of esters in Chardonnay wine. RESULTS: The concentration of acetate esters of higher alcohols decreased in all the wines independently of the vinification method. However, the ethyl esters of fatty acids decreased in wine aged in barrel and increased in wine aged in bottle, so it would seem that these compounds interact with the lees present in the barrels and/or with the wood of the barrel. The ethyl esters of organic acids increased during ageing both in barrel and bottle. CONCLUSION: The ageing of Chardonnay wine in barrel on lees did not favour the formation of esters compared to the same wine aged in bottle. Copyright © 2009 Society of Chemical Industry     

Characterization of railway line impedance based only on short‐circuit measurements

This paper presents a new methodology to obtain the line impedance of current railway tracks by using only short‐circuit measurements. Open‐circuit measurements required by conventional methodologies are discarded, since they cannot be carried out for railway tracks in service (electrically continuous and indefinite length). The mathematical basis of the proposed methodology is based on the transmission line theory but focused on the changes in track length. The proposal has been successfully applied to characterize the impedance of the high‐speed railway line at the Spanish AVE Madrid–Valencia (Cuenca) and in the AVE Atocha–Chamartin tunnel (Madrid). Copyright © 2014 John Wiley & Sons, Ltd.     

Air quality data from large cities

This paper presents an assessment of the air quality for the principal cities in developed and developing countries. Part of the vast and widely dispersed information on air quality that is available at this time on the Internet was compiled, thus making possible a comprehensive evaluation of the tendencies that emerged at the end of the 20th century. Likewise, these values are compared to the air quality thresholds recommended by two international organizations: guideline levels of the World Health Organization (WHO) and limit values of the European Union (EU), in order to determine air quality concentration levels in large cities around the world. The current situation of air quality worldwide indicates that SO(2) maintains a downward tendency throughout the world, with the exception of some Central American and Asian cities. NO(2) maintains levels very close to the WHO guideline value around the world. For particulate matter, it is a major problem in almost all of Asia, exceeding 300 microg/m(3) in many cities. Ozone shows average values that exceed the selected guideline values in all of the analyses demonstrating that it is a global problem. In general, the worldwide trend is to a reduction in the concentrations of pollutants because of the increasingly strong restrictions which local governments and international organizations impose. However, in poor countries and those with low average incomes, concentrations of air pollutants remain high and the trend will be the elevation of their ground levels as they develop, making the problem even worse.     

Development of tailored high-performance and durable electrocatalysts for advanced PEM fuel cells

A family of novel carbon materials with intermediate surface area and varying morphology and surface chemistry were used to prepare Pt/C catalysts by two different preparation procedures; a chemical impregnation method and a microwave-assisted polyol method. The catalysts were thoroughly characterized, and their electrochemical performance and stability were investigated with rotating disc electrode (RDE) cyclic voltammetric (CV) measurements. The intermediate-surface-area carbon supports gave catalysts with much greater support stability than a widely used standard catalyst. The novel catalysts had lower electrochemical surface area than the reference, but their specific electrocatalytic activity towards the oxygen-reduction reaction (ORR) was much higher, and some of them also featured higher mass-specific ORR activity than the reference. The series of catalysts prepared by the microwave-assisted polyol method featured smaller Pt nanoparticles and higher activities than those prepared by impregnation. On the other hand, the impregnated catalysts showed better durability of the Pt particles. The most promising catalysts were selected and elaborated in further optimized preparation procedures to obtain quantities sufficient for their use in proton-exchange membrane fuel cells (PEMFCs).     

Effect of hydrogen on dislocation nucleation in alloy 718

In situ electrochemical nanoindentation has been used to study the effect of hydrogen on the nanomechanical response of Alloy 718. Observations show that hardness increase as a result of hydrogen charging. Also, the hydrogen charging gives a reduced pop-in load and pop-in width. This is related to a reduction in the energy needed for dislocation nucleation and the mobility of the dislocations in the presence of hydrogen. Two grains with different orientations has been tested here. The pop-in load and width obtained in the (101) orientation was more affected by the presence of hydrogen than those achieved in the (111) oriented grain.