Analysis of electric arc furnaces efficiency via frequency spectrum-based arc coverage detection

We introduce the analysis of variables measured outside a direct current electric arc furnace that are related to the arc coverage and its electric energy efficiency. We derive an on-line reference to the arc coverage suitable for control decisions. In order to do so, we study the furnace shell vibration frequency spectrum as structure-borne sound sensed by a microphone. The data is analysed using real time software tools to obtain the sound signal spectrum associated with arc coverage likewise related to the optimal performance of the furnace. A statistical test is performed to prove the relationship between sound and electric energy efficiency.     

On locally reversible languages

There exist several works that study the class of reversible languages defined as the union closure of 0-reversible languages, their properties and suitable representations. In this work we define and study the class of locally reversible languages, defined as the union closure of $k$-reversible languages. We characterize the class and prove that it is a local (positive) variety of formal languages. We also extend the definition of quasi-reversible automata to deal with locally reversible languages and propose a polynomial algorithm to obtain, for any given locally $k$-reversible language, a quasi-$k$-reversible automaton.     

Analysis of the interface and bond strength of resin-based endodontic cements to root dentin

This study evaluated by scanning electron microscopy the interface between root dentin and resin cements, with or without additional application of a dual-cured one-step self-etching dentin adhesive. In addition, the push-out bond strength of these materials to dentin was evaluated. Root canals of 50 maxillary human canines were subjected to biomechanical preparation and randomly assigned into five groups (n = 10) according to the obturation employed: I. AH Plus/gutta-percha; II. Endo-REZ/gutta-percha; III. Epiphany SE/Resilon; IV. Endo-REZ/gutta-percha + adhesive; and V. Epiphany SE/Resilon + adhesive. After obturation, two cross sections of 1.0 mm of each third of the root were obtained and analyzed by SEM and push-out. Data were analyzed by Kruskal-Wallis, Two-way ANOVA and Tukey's HSD tests (α = 5%). Significant differences occurred between scores for gap parameters and tags; greater tag formation resulted for Epiphany SE (P < 0.05). There were also significant differences between groups for the bond strength. AH Plus (1.24 ± 0.70) showed higher values (P < 0.05) compared to groups II (0,17 ± 0.19), III (0.10 ± 0.06), IV (0.09 ± 0.08), and V (0.06 ± 0.03), which were statistically similar (P > 0.05). There was no significant difference between the root thirds (P > 0.05). It was concluded that the use of a self-etching adhesive system did not improve the adhesion of resin-based sealers to dentin and that AH Plus showed better bond strength when compared to other cements.     

Hydrological and sediment transport dynamics of flushing flows: implications for management in large Mediterranean Rivers

Flushing flows have been implemented in the lower Ebro River since 2003, with the principle objective of removing excess macrophytes. This paper describes the hydrology and sediment transport of these flushing flows in comparison with natural floods and discusses their effects in terms of riverbed adjustments. During flushing flows suspended sediment, concentration is more constant and double that of natural floods, although discharge is lower. Flashiness, measured as the rate of discharge increase per unit time, is an order of magnitude higher during flushing flows than during natural events. Consequently, flushing flows exhibit higher transport capacity than their natural counterparts despite their considerably lower magnitude and duration. Flushing flows remove up to 95% of macrophytes close to the dam, but their effectiveness reduces with distance downstream. Despite several constraints, flushing flows have significant potential to entrain and transport sediment and careful management of these releases may, therefore, play an important role in enhancing physical habitat in the river and supply sediment to the delta. The River Ebro case study shows that flushing flows are not incompatible with HEP production, and may actually result in a positive trade‐off due to reduced clogging of water intakes. Nevertheless, it remains important to reassess their effectiveness regularly and monitor adverse geomorphic effects such as riverbed degradation. In summary, flushing flows are an important instrument of river management, but one which must be employed as part of a spectrum of approaches to enhance physical habitat conditions. Copyright © 2008 John Wiley & Sons, Ltd.     

Apel: A Graphical Yet Executable Formalism for Process Modeling

Software process improvement requires high level formalisms for describing project-specific, organizational and quality aspects. These formalisms must be convenient not only for capture but also for execution purposes. In order to fulfill these requirements and to build a software process environment capable of supporting engineering tasks we have designed a new graphical, but still enactable, formalism called APEL (for Abstract Process Engine Language).APEL is very ambitious in the sense that it aims to cover a wide spectrum of needs and approaches expressed not only in the software engineering field but also in many others such as real-time systems, object-oriented methodologies, tool integration, CSCW, workflow and information systems. It is then not surprising to see that many concepts and techniques used in APEL are borrowed from these connected fields. A major outcome of the work presented here was to integrate a broad range of concepts and paradigms in a single and coherent framework, but on the basis of a minimal set of primitive concepts which make it very easy to extend. Globally, the aspects which received most attention are: openness, reuse, scalability, human orientation and cooperative work.     

Sea breeze modulated volatilization of polycyclic aromatic hydrocarbons from the Masnou Harbor (NW Mediterranean Sea)

Harbors, marinas, and coastal environments are impacted by important pollutant loadings, particularly of polycyclic aromatic hydrocarbons (PAHs). Air-water exchange is an important process driving the environmental fate of organic pollutants in aquatic environments. However, its relevance as a factor affecting the environmental fate of pollutants from harbor sediments and waters has not been properly assessed, so far, except for few coastal environments. The objective of this study is to quantify the importance of volatilization losses of PAHs from harbor sediments and waters and to study the potential role of sea breeze as a modulator of air-water exchange in coastal environments. The results show that volatilization fluxes from a medium size marina located in the NW Mediterranean sea are relatively high in comparison to those observed in other aquatic systems, particularly for the low molecular weight (MW) compounds. This is consistent with PAHs profiles observed in harbor sediments, which are depleted by the lower MW hydrocarbons. Therefore, volatilization is an important loss of low MW PAHs such as phenanthrene, methyl phenanthrene, dibenzothiophene, etc. Indeed, these PAHs have a residence time of few days in the harbor waters and sediments. Finally, the diurnal trends in volatilization fluxes mimics that of the sea breeze influenced wind speed. These results show the important role that the diurnal sea breeze exerts on the environmental fate of pollutants such as PAHs in coastal environments as a modulator of air-water exchange and as a potential driver of transport of pollutants between adjacent coastal and terrestrial environments.     

Development of a liquid chromatography-electrospray-tandem mass spectrometry method for the quantitative determination of benzoxazinone derivatives in plants

A new method for the quantification of benzoxazinone derivatives in extracts of wheat foliage and root samples using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) is described. Using this method, the characterization, separation, and quantitative detection of a mixture of six naturally occurring 1,4-benzoxazin-3(4H)-one derivatives, including the hydroxamic acids (DIMBOA, DIBOA), lactams (HBOA, and HMBOA), benzoxazilinones (BOA, MBOA), and two synthetic methoxylated variations of DIBOA and HBOA, was achieved. The application of a novel, highly modified reversed-phase LC column, the dodecyl (C12) TMS end-capped Synergi MAX-RP, enhanced the on-line chromatographic separation through improvements to component resolution, analyte stability and peak shape and also to the column lifetime. The complete ESI-MS-MS precursor-product ion fragmentation pathways for the benzoxazinone derivatives are described for the first time and used to deduce a generic fragmentation pattern for the compound class. Characteristic transitions for the benzoxazinones were thus used in the developed analytical method enabling reliable quantification with simultaneous screening for other potentially present derivatives, while eliminating interferences from other coeluting contaminants from the complex plant extract matrix. Quantitative analysis was done in the multiple reaction monitoring mode, using two specific combinations of a precursor-product ion transitions for each compound. The ESI-MS-MS detection method offered improvements to the sensitivity and selectivity, as compared with previously applied LC methods, with detection limits down to 0.002-0.023 ng/microL. The developed method was demonstrated by analyzing foliages and roots of six different wheat cultivars using pressurized liquid extraction-solid-phase extraction cleanup-LC-ESI-MS-MS. The analytes were detected in the range of 0.7-207 microg/g of dry weight.     

Picogram per liter level determination of estrogens in natural waters and waterworks by a fully automated on-line solid-phase extraction-liquid chromatography-electrospray tandem mass spectrometry method

The present work describes a novel, fully automated method, based on on-line solid-phase extraction-liquid chromatography-electrospray tandem mass spectrometry (SPE-LC-ESI-MS-MS), which allows the unequivocal identification and quantification of the most environmentally relevant estrogens (estradiol, estrone, estriol, estradiol-17-glucuronide, estradiol-17-acetate, estrone-3-sulfate, ethynyl estradiol, diethylstilbestrol) in natural and treated waters at levels well below those of concern (limits of quantification between 0.02 and 1.02 ng/L). The method is highly precise, with relative standard deviations varying between 1.43 and 3.89%, and accurate (recovery percentages >74 %). This method was used to track the presence and fate of the target compounds in a waterworks and to evaluate the removal efficiency of the treatment processes applied. Only estrone and estrone-3-sulfate were detected in the river water used as source (at 0.68 and 0.33 ng/L, respectively). After progressive removal through the various treatment steps, none of them were detected in the finished drinking water. In addition to selectivity, sensitivity, repeatability, and automation (up to 15 samples plus 6 calibration solutions and 1 blank can be analyzed unattended), this technique offers fairly high throughput (analysis time per sample is 60 min), low time and solvent consumption, and ease of use.     

Lipid and protein stability of partially defatted walnut flour (Juglans regia L.) during storage

Partially defatted walnut flour (WF) was stored (25 °C, 800 Lux) for an 8‐month period and evaluated monthly in some protein properties and oil oxidative parameters. Transparent plastic‐laminated (WFPL) and plastic‐laminated, aluminium‐coated (WFAC) packages were used. During the first 3 months, samples were more susceptible to endogenous hydrolysis; an increase in soluble peptide concentration was determined for both WFAC and WFPL. Minor changes between WFAC and WFPL were observed in protein electrophoretic patterns along storage period, but no differences were determined in total protein solubility. However, a progressive reduction in water‐holding capacity (47% from time 0 to month 8) was observed for WFPL. A major effect of packaging material was found on lipid‐quality parameters. Packaging materials’ barrier to light effectively protect WF against polyunsaturated FA degradation and oil oxidation. Lipids from WF stored in plastic‐laminated packages showed decreasing double‐bond index values (from 1.71 at initial time, to 1.45 after 6 months of storage) and increasing oxidation rates along storage test. Aluminium‐coated packages can be used to keep quality of WF for 8 months at room temperature.     

Occurrence and specific congener profile of 40 polybrominated diphenyl ethers in river and coastal sediments from Portugal

Forty polybrominated diphenyl ethers (PBDEs), from mono- through hepta-brominated, were analyzed in river and coastal sediment samples of the eight main river basins of Portugal to investigate the occurrence, geographical distribution, and detailed congener profiles. Thirty-two sediment samples taken along the different rivers from inland to the open sea revealed an increase toward the river mouth with a total PBDE concentration of 20 ng/g-dw, and levels decreased to 0.5 ng/g-dw in coastal sediments. PBDEs were detected in all samples analyzed, indicating a diffuse source of pollution in the aquatic environments. Maximum levels were encountered in sediments collected close to urban and industrial areas. Of 40 congeners included in the analytical work, 17 congeners were detected in river sediments. BDE 47 was found in all samples analyzed whereas BDEs 100 and 99 were found in more than 26 out of 32 samples analyzed at concentrations from 0.03 to 10 ng/g-dw. This study is unique in showing the presence of previously nondescribed lower brominated PBDEs in riverine and marine sediments. BDEs 7, 11, 12+13, 15, 30, 32, 17, 25, 28+33, 49, 75, and 71 were identified in two to five samples with a median of 0.03-0.55 ng/g-dw. The analytical method developed consisted of the use of Soxhlet extraction with a novel cleanup method employing alumina cartridges and analysis by gas chromatography-mass spectrometry operated in negative chemical ionization mode.