Tensile Work Hardening Modeling of Precipitation Strengthened Nb-Microalloyed Steels

Very often Nb contributes to the strength of a microalloyed steel beyond the expected level due to the grain size strengthening resulting from thermomechanical processing. Two different mechanisms are behind this phenomenon, and both of them have to do with the amount of Nb remaining in the solution after hot rolling. The first of them is the increase of the hardenability of the steel due to Nb, and the second one is the fine precipitation of NbC in ferrite. The contribution of the precipitates to the work hardening of two thermally and thermomechanically processed microalloyed steels is addressed in this work and this contribution has been integrated into previously developed models by the authors for ferrite–pearlite microstructures. An L _eff is considered through the effective spacing associated to the different obstacles and their interactions with the moving dislocations. The model obtained shows good agreement with the experimental tensile curves from the end of yield point elongation to the onset of necking.

     

Impact of Process Parameters on Listeria innocua Inactivation Kinetics by Pulsed Light Technology

The impact of several pulsed light (PL) processing parameters on microbial inactivation was evaluated in buffered water systems using Listeria innocua as test microorganism. Reduction in L. innocua population increased directly with pulse energy, pulse fluence and the number of light pulses, and inversely with the distance between samples and a xenon lamp. Overall, the higher the amount of light received by the target microorganism by both direct and reflected light, the larger the loss of cell counts. Total fluence striking on the samples per area unit was shown to be the most relevant process factor affecting L. innocua inactivation by PL. Microbial population decreased with total fluence, obtaining more than 7 log reductions after 0.4 J?cm^?2. The inactivation kinetics was clearly sigmoidal, showing an initial shoulder in the inactivation curve. No significant reduction (<1 log) in L. innocua counts was induced at fluences lower than 0.04 J?cm^?2. From this threshold total fluence, L. innocua inactivation increased exponentially to the maximum detectable level. Since total fluence is the most relevant process factor affecting microbial inactivation by PL, this parameter must be reported to describe PL processing conditions.     

Thermal energy performance in working-spaces from biomorphic models: The tuna case in an office building

This paper is comprehended in the study of the application of the biomimicry science in building services and energy management, taking as a reference the case of tuna. Tuna generates heat in the muscles, organs and tissues of the inner area of its body (dark muscles). This heat is distributed in the periphery in order to maintain constant body temperature. From this biological reality, researchers analyse the possibility of altering the heating demand of an office on the basis of the heat conservation strategy applied by tuna, merely modifying the working-spaces. For this purpose, an existing office building with high architectonical quality parameters has been chosen and different scenarios have been defined in order to perform the energy simulations. The case studies correspond to the variations in the floor layout and occupancy density distribution. Besides, they are studied in three European cities with different climate. The evaluation of results is mainly focused on the heating demand since tuna strategy comprises the heat management. It is shown that the arrangement of high thermal load locals affects the heating demand of the building, being more efficient the tuna distribution in order to lower the demand.

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Land prices and housing prices: the case of Spain

This research analyzes the Granger causality relation between land and housing prices in Spain. This relation is examined using Spanish provincial quarterly observations for the period 2005Q1–2010Q2. The results show that there is a bidirectional relationship between both markets. However, while the causality from the housing market to the land market is clear, the causality in the opposite direction, although statistically significant, is much weaker.     

Solvent‐free synthesis of glycerol carbonate and glycidol from 3‐chloro‐1,2‐propanediol and potassium (hydrogen) carbonate

BACKGROUND: An indirect solvent‐free synthetic approach for obtaining glycerol carbonate and glycidol from glycerol and CO₂ through their more reactive and easily synthesizable derivatives 3‐chloro‐1,2‐propanediol (HAL) and potassium (hydrogen) carbonate has been studied. RESULTS: The reaction is fast with source of carbonation and temperature having a strong influence on the results. A yield of 80% glycerol carbonate together with a simultaneous substantial production of glycidol (0.56 mol mol^?1 glycerol carbonate) are obtained using K₂CO₃ as the carbonation source at 80 °C, a reaction time of 30 min and a 3:1 HAL/K₂CO₃ molar ratio. A lower yield of glycerol carbonate (60%) is obtained from KHCO₃ after 50 min with the other experimental conditions remaining unchanged. In this case, glycidol formation is zero or insignificant. Glycerol is also obtained in high yields, although in much lower amounts from KHCO₃ (～0.59 mol mol^?1 glycerol carbonate independent of operating conditions) than from K₂CO₃ (0.84–1.1 mol mol^?1 glycerol carbonate, depending on experimental conditions). CONCLUSIONS: The proposed synthetic strategy overcomes the currently difficult direct reaction between glycerol and CO₂, leading to the simultaneous synthesis of two valuable chemicals: glycerol carbonate and glycidol. However, glycerol is also obtained in substantial amounts thus decreasing the overall yield of the process. Thus, methods for preventing its formation must be developed for industrial feasibility. Copyright © 2010 Society of Chemical Industry     

Planning working time accounts under demand uncertainty

Working time accounts (WTAs) are employer-oriented flexibility systems that have been applied in industry but could be used far more. WTAs enable capacity to be adapted to fluctuations in demand. The required capacity, which is needed to plan WTAs, usually depends on several factors. It is often impossible to reliably predict the required capacity or unrealistic to adjust it to a probability distribution. In some cases, a set of required-capacity scenarios can be determined, each with a related probability. This paper presents a multistage stochastic optimisation model that is robust (i.e., provides a solution that is feasible for any possible scenario) and minimises the expected total cost (which includes the cost of overtime and the cost of the capacity shortage).     

Quantitative assessment of mobile web guidelines conformance

Conformance metrics for the mobile web can play a crucial role as far as engineering mobile websites are concerned, especially if they are automatically obtained. In this way, developers can have an idea in numeric terms of how suitable their developments are for mobile devices. However, there are a plethora of devices with their own particular features (screen size, formats support, etc.) that restrict a unified automatic assessment process. This paper proposes a tool-supported method for device-tailored assessment in terms of conformance with Mobile Web Best Practices 1.0, including the definition of five quantitative metrics for automatically measuring mobile web conformance: Navigability, Page layout, Page definition, User input and Overall score. The behaviour of these metrics was analysed for different devices and different web paradigms, both mobile web pages and their equivalent desktop pages. As expected, the results show that mobile web pages on more capable devices score higher. In addition, 20 users took part in an experiment aimed at discovering how conformance-based scores relate to usability dimensions. The results demonstrate that automatic scoring approaches strongly correlate with usability scores obtained by direct observation, such as task completion time and user satisfaction. This correlation is even stronger for the device-tailored assessment than the one that assumes a general profile for all devices. For instance, results show a strong negative correlation between Overall score and task completion time: ρ (9) = −0.81, (p < 0.05) for the generalist approach and ρ (9) = −0.88 for the device-tailored one, entailing that mobile web guidelines and the metrics based on their conformance capture usability aspects. This result challenges the widely accepted belief that conformance to guidelines does not imply more usable web pages, at least for web accessibility conformance.     

Biolubricants and triboreactive materials for automotive applications

The research institution TEKNIKER has coordinated the EUROPEAN Project EREBIO, were different biodegradable lubricants have been formulated by FUCHS and BAM for heavy duty engines (GUASCOR), and passenger cars (RENAULT). In the frame of this article, it has been summarised the results obtained when developing biodegradable passenger car lubricants in combination with triboreactive materials.Replacing hydrocarbon-based oils with biodegradable products is one of the ways to reduce adverse effects on the ecosystem caused by the use of lubricants. The application of low or no sulphur, ash and phosphorous (lowSAP) ester- or polyglycol-based oils, intended for passenger car engine lubricants as substitutes for hydrocarbon-based oils, required the preparation of a composition of lubricants with comparable tribological and functional properties.The study is focussed on passenger car motor oils (PCMO) with reduced metal-organic additives. This is necessary in order to reduce the ash build-up in the after treatment system and therefore improve its efficiency and lifetime. High fuel efficiency and long drain intervals are requested, as well. To follow a line in a consequent way, these oils have to be biodegradable and non-toxic to the aqueous environment according to the directive EC/1999/45, coherent with other international standard. In a modern diesel or gasoline engine, the engine oils has to fulfil quite a number of different functions, such as lubricating and cooling the system, wear protection, soot and particle handling with less deposit tendency and so on.In the paper a study of the biodegradability, toxicity and the tribological properties has been carried out for new developed prototype engine bio-oils. Also, some different plasma sprayed triboreactive coatings have been deposited on cast iron piston rings, being studied also their tribological properties. Finally, the behaviour of the new bio-oils selected and plasma sprayed triboreactive coatings on piston rings have been screened in a real engine.     

Highly sensitive PCR-based detection method specific for Aspergillus flavus in wheat flour

Aspergillus flavus is frequently found in food, producing a wide variety of toxins, aflatoxins being the most relevant in food safety. A specific PCR-based protocol for this species is described which allowed discrimination from other closely related species having different profiles of secondary metabolites from the Aspergillus Section Flavi, particularly A. parasiticus. The specific primers were designed on the multi-copy internal transcribed region of the rDNA unit (ITS1-5.8S-ITS2 rDNA) and were tested in a wide sample of related species and other fungal species commonly found in food. The PCR assay was coupled with a fungal enrichment and a DNA extraction method for wheat flour to enhance the sensitivity of the diagnostic protocol. The results indicated that the critical PCR amplification product was clearly observed for wheat flour contaminated by 10(2) spores after 16 h of incubation.     

Forecasting Weekly Evapotranspiration with ARIMA and Artificial Neural Network Models

Information about the parameters defining water resources availability is a key factor in their management. Reference evapotranspiration (ET0) prediction is fundamental in planning, design, and management of water resource systems for irrigation. The application of time series analysis methodologies, which allow evapotranspiration prediction, is of great use for the latter. The objective of the present study was the comparison of weekly evapotranspiration ARIMA and artificial neural network (ANN)-based forecasts with regard to a model based on weekly averages, in the region of álava situated in the Basque Country (northern Spain). The application of both ARIMA and ANN models improved the performance of 1?week in advance weekly evapotranspiration predictions compared to the model based on means (mean year model). The ARIMA and ANN models reduced the prediction root mean square differences with respect to the mean year model (based on historical averages) by 6–8%, and reduced the standard deviation differences by 9–16%. The variations in the performances of the prediction models evaluated depended on the weekly evapotranspiration patterns of the different months.