Line patterning of graphite and the fabrication of cheap, inexpensive, “throw-away” sensors

A new simple method (“line patterning technique”) using only standard office equipment is described whereby clearly defined, electrically conducting patterns of graphite can be deposited on polymer (plastic) or paper substrates. The properties of the conductive patterns have been characterized by electrical conductivity and SEM measurements. Sensors were constructed by using interdigitated patterns of graphite deposited on plastic and paper, and coated with a thin film of conducting electronic polymer, e.g. polyaniline emeraldine salt.     

Fixed-point DSP implementation of nonlinear controller for large gap electromagnetic suspension system

Electromagnetic suspension systems are inherently nonlinear and often face hardware limitation when digitally controlled. The main contributions of this paper are: the design of a nonlinear H_∞ controller, including dynamic weighting functions, applied to a large gap electromagnetic suspension system and the presentation of a procedure to implement this controller on a fixed-point DSP, through a methodology able to translate a floating-point algorithm into a fixed-point algorithm by using l_∞ norm minimization due to conversion error. Experimental results are also presented, in which the performance of the nonlinear controller is evaluated specifically in the initial suspension phase.     

Mining the impact of evolution categories on object-oriented metrics

Despite the relevance of the software evolution phase, there are few characterization studies on recurrent evolution growth patterns and on their impact on software properties, such as coupling and cohesion. In this paper, we report a study designed to investigate whether the software evolution categories proposed by Lanza can be used to explain not only the growth of a system in terms of lines of code (LOC), but also in terms of metrics from the Chidamber and Kemerer (CK) object-oriented metrics suite. Our results show that high levels of recall (ranging on average from 52 to 72 %) are achieved when using LOC to predict the evolution of coupling and size. For cohesion, we have achieved smaller recall rates (<27 % on average).     

Development and evaluation of active packaging for sliced mozzarella preservation

Antimicrobial films were formed by the incorporation of nisin (NI), natamycin (NA) and a combination of both (NI + NA) into cellulose polymer. Film efficacies were evaluated in vitro against Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 15313, Penicillium sp. and Geotrichum sp. The films were also evaluated on sliced mozzarella cheese against moulds and yeasts, Staphylococcus sp. and psychrotrophic bacteria. Mechanical and microscopic properties of the films and the diffusion of the antimicrobial agents from the film to the cheese were also evaluated. Films containing NI showed an antimicrobial effect in vitro against S. aureus and L. monocytogenes, while films containing NA were effective in vitro against Penicillium sp. and Geotrichum sp. By the ninth day of storage at 12 ± 2°C, the count of yeasts and moulds on cheese covered with films containing NA decreased 2 log10 units compared with the count on cheese with control films. NI film did not show an effect against Staphylococcus sp., but it was effective against psychrotrophic bacteria for 6 days of storage of the cheese. The incorporation of antimicrobial compounds decreased the resistance and elongation of the films and caused changes in their molecular conformation. NI diffusion from the films to the cheese was not detected; however, time‐dependent diffusion of NA from the film containing NI + NA was measured. The incorporation of NI and NA together in the films did not show an effect. The film containing NA showed potential for application as active food packaging for sliced mozzarella cheese. Copyright © 2008 John Wiley & Sons, Ltd.     

在石油为主要能源的世界中发展乙醇生产——巴西乙醇生产的经验

当前，人们生活在依赖石油的世界中，因为汽油和柴油的价格不断升高，许多国家都在寻求化石燃油的替代物。用糖类作物或谷物生产的乙醇被视为最好的替代物。然而，全球目前乙醇产量仅为汽油耗量的2．5％，所以乙醇需求增长迅速，市场广阔。介绍了巴西乙醇生产的经验；在乙醇市场波动的情况下，乙醇生产商得以生存的措施；乙醇生产商的生产方式；乙醇生产所用糖浆原料的概况等。     

Dynamic simulation and experimental evaluation of EPDM terpolymerization with vanadium-based catalyst

The development of a simplified kinetic model describing some effects observed in catalyzed olefin terpolymerization is presented. Based on the method of moments, the model describes the influence of Al/V ratio and diene concentration on reaction yield and on polymer characteristics such as molecular weight, ethylene incorporation, and polydispersity. In order to verify the model validity, the terpolymerization reactions were performed using VOCl₃–Al₂Et₃Cl₃ systems and 2-ethylidenebi-cyclo[2.2.1]hept-5-ene (ENB) as diene. The results of dynamic simulation fit well the experimental data for Al/V up to 15, but the model fails under high diene concentration, where branching reactions, neglected by reason of simplification, become significant. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1173–1189, 1998     

The cooling effect of green spaces as a contribution to the mitigation of urban heat: A case study in Lisbon

Green areas in the urban environment can contribute to the mitigation of the Urban Heat Island. In a context of climate change, with the expected increase in temperature, dryness and intensity of heat waves, green areas assume even higher importance as they can create a cooling effect that extends to the surrounding areas. This study analyses the thermal performance of a small green space (0.24 ha) and its influence in the surrounding atmospheric environment of a densely urbanised area in Lisbon. Measurements of weather parameters (temperature, relative humidity, wind speed, solar and infrared radiation) were carried out along a selected path, starting from inside the green area to surrounding streets with different orientations and solar exposure. It was found that the garden was cooler than the surrounding areas, either in the sun or in the shade. These differences were higher in hotter days and particularly related to the mean radiant temperature (Tmrt). The highest difference found was of 6.9 °C in relation to air temperature and 39.2 °C in relation to Tmrt; in both cases this difference occurred between the shaded site inside the garden and the sunny site in an E–W oriented street in the southern part of the studied area. Besides the local weather conditions, particularly the low wind speed, the sun exposure and the urban geometry are the potential factors that explain these differences. The cooling effect of green areas on the surrounding environment can be enhanced by additional measures related to the urban features of each city.