173 resultados para Systems engineering
Resumo:
The Piracicaba, Capivari, and Jundiai River Basins (RB-PCJ) are mainly located in the State of So Paulo, Brazil. Using a dynamics systems simulation model (WRM-PCJ) to assess water resources sustainability, five 50-year simulations were run. WRM-PCJ was developed as a tool to aid decision and policy makers on the RB-PCJ Watershed Committee. The model has 254 variables. The model was calibrated and validated using available information from the 80s. Falkenmark Water Stress Index went from 1,403 m(3) person (-aEuro parts per thousand 1) year (-aEuro parts per thousand 1) in 2004 to 734 m(3) P (-aEuro parts per thousand 1) year (-aEuro parts per thousand 1) in 2054, and Xu Sustainability Index from 0.44 to 0.20. In 2004, the Keller River Basin Development Phase was Conservation, and by 2054 was Augmentation. The three criteria used to evaluate water resources showed that the watershed is at crucial water resources management turning point. The WRM-PCJ performed well, and it proved to be an excellent tool for decision and policy makers at RB-PCJ.
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Using a dynamic systems model specifically developed for Piracicaba, Capivari and Jundia River Water Basins (BH-PCJ) as a tool to help to analyze water resources management alternatives for policy makers and decision takers, five simulations for 50 years timeframe were performed. The model estimates water supply and demand, as well as wastewater generation from the consumers at BH-PCJ. A run was performed using mean precipitation value constant, and keeping the actual water supply and demand rates, the business as usual scenario. Under these considerations, it is expected an increment of about similar to 76% on water demand, that similar to 39% of available water volume will come from wastewater reuse, and that waste load increases to similar to 91%. Falkenmark Index will change from 1,403 m(3) person(-1) year(-1) in 2004, to 734 m(3) P(-1) year(-1) by 2054, and the Sustainability Index from 0.44 to 0.20. Another four simulations were performed by affecting the annual precipitation by 90 and 110%; considering an ecological flow equal to 30% of the mean daily flow; and keeping the same rates for all other factors except for ecological flow and household water consumption. All of them showed a tendency to a water crisis in the near future at BH-PCJ.
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Aeration and agitation are important variables to ensure effective oxygen transfer rate during aerobic bioprocesses: therefore, the knowledge of the volumetric mass transfer coefficient (k(L)a) is required. In view of selecting the optimum oxygen requirements for extractive fermentation in aqueous two-phase system (ATPS), the k(L)a values in a typical ATPS medium were compared in this work with those in distilled water and in a simple fermentation medium. in the absence of biomass. Aeration and agitation were selected as the independent variables using a 2(2) full factorial design. Both variables showed statistically significant effects on k(L)a, and the highest values of this parameter in both media for simple fermentation (241 s(-1)) and extractive fermentation with ATPS (70.3 s(-1)) were observed at the highest levels of aeration (5 vvm) and agitation (1200 rpm). The k(L)a values were then used to establish mathematical correlations of this response as a function of the process variables. The exponents of the power number (N(3)D(2)) and superficial gas velocity (V(s)) determined in distilled water (alpha = 0.39 and beta = 0.47, respectively) were in reasonable agreement with the ones reported in the literature for several aqueous systems and close to those determined for a simple fermentation medium (alpha=0.38 and beta=0.41). On the other hand, as expected by the increased viscosity in the presence of polyethylene glycol, their values were remarkably higher in a typical medium for extractive fermentation (alpha=0.50 and beta=1.0). A reasonable agreement was found between the experimental data of k(L)a for the three selected systems and the values predicted by the theoretical models, under a wide range of operational conditions. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
Adsorption of Ni(2+), Zn(2+) or Pb(2+) by dry biomass of Arthrospira (Spirulina) platensis and Chlorella vulgaris was studied as a function of contact time and initial metal concentration. The zero point of charge calculated for these biosorbents (pH(zpc) 4.0 and 3.4, respectively) and additional pH tests suggested the use of pH in the range 5.0-5.5 for the experiments. The equilibrium isotherms were evaluated in terms of maximum sorption capacity and sorption affinity. The pseudo first and second order kinetic models were considered to interpret the experimental data, and the latter best described the adsorption system. Both the Freundlich and Langmuir models were shown to well describe the sorption isotherms, thus suggesting an intermediate mono/multilayer sorption mechanism. Compared to A. platensis (q(e) = 0.354, 0.495 and 0.508 mmol g(-1) for Ni(2+), Pb(2)+ and Zn(2+), respectively), C. vulgaris behaved as a better biosorbent because of higher equilibrium sorption capacity (q(e) = 0.499, 0.634 and 0.664 mmol g(-1), respectively). The removal efficiency decreased with increasing metal concentration, pointing out a passive adsorption process involving the active sites on the surface of the biomasses. The FT-IR spectroscopy evidenced that ions removal occurred mainly by interaction between metal and carboxylate groups present on both the cell walls. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
This work is the first attempt to apply aqueous two-phase mixed micellar systems (ATPMS) of the nonionic surfactant Triton X-114 and the anionic one AOT to extract clavulanic acid (CA) from broth fermented by Streptomyces clavuligerus. Cloud points were determined in McIlvane buffer pH 6.5 with or without NaCl, and diagram phases/coexistence curves were constructed. CA partition was investigated following a 2(4)-full factorial design in which AOT (0.022, 0.033 and 0.044% w/w), Triton X-114 (1.0, 3.0 and 5.0% w/w) and NaCl (0, 2.85 and 5.70% w/w) concentrations and temperature (24,26 and 28 degrees C) were selected as independent variables, and CA partition coefficient (K(CA)) and yield in the top phase (eta(CA)) as responses. CA partitioned always to the top, micelle-poor phase. The regression analysis pointed out that NaCl concentration and interaction between temperature and Triton X-114 concentration had statistically significant effects on K(CA), while eta(CA) was mainly influenced by temperature, Triton X-114 concentration and their interaction. Different ATPMS compositions were then needed to maximize these responses, specifically 0.022% (w/w) AOT, 5% (w/w) Triton X-114 for K(CA) (2.08), and 0.044% (w/w) AOT, 1% (w/w) Triton X-114 for eta(CA) (98.7%), both at 24 degrees C without NaCl. Since at 0.022% (w/w) AOT, 1% (w/w) Triton X-114 and 28 degrees C without NaCl the system was able to ensure satisfactory intermediate results (K(CA) = 1.48; eta(CA) = 86.3%), these conditions were selected as the best ones. These preliminary results are of concern for possible industrial application, because CA partition to the dilute phase can simplify the subsequent purification protocol. (C) 2011 Elsevier B.V. All rights reserved.
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BACKGROUND: Aqueous two-phase micellar systems (ATPMS) are micellar surfactant solutions with physical properties that make them very efficient for the extraction/concentration of biological products. In this work the main proposal that has been discussed is the possible applicability and importance of a novel oscillatory flow micro-reactor (micro-OFR) envisaged for parallel screening and/or development of industrial bioprocesses in ATPMS. Based on the technology of oscillatory flow mixing (OFM), this batch or continuous micro-reactor has been presented as a new small-scale alternative for biological or physical-chemical applications. RESULTS: ATPMS experiments were carried out in different OFM conditions (times, temperatures, oscillation frequencies and amplitudes) for the extraction of glucose-6-phosphate dehydrogenase (G6PD) in Triton X-114/buffer with Cibacron Blue as affinity ligand. CONCLUSION: The results suggest the potential use of OFR, considering this process a promising and new alternative for the purification or pre-concentration of bioproducts. Despite the applied homogenization and extraction conditions have presented no improvements in the partitioning selectivity of the target enzyme, when at rest temperature they have influenced the partitioning behavior in Triton X-114 ATPMS. (C) 2011 Society of Chemical Industry
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The partitioning of Green Fluorescent Protein (GFP) in poly(ethylene glycol)/Na-poly(acrylate) aqueous two-phase systems (PEG/NaPA-ATPS) has been investigated. The aqueous two-phase systems are formed by mixing the polymers with a salt and a protein solution. The protein partitioning in the two-phase system was investigated at 25 degrees C. The concentration of the GFP was measured by fluorimetry. It was found that the partitioning of GFP depends on the salt type, pH and concentration of PEG. The data indicates that GFP partitions more strongly to the PEG phase in presence of Na2SO4 relative to NaCl. Furthermore, the GFP partitions more to the PEG phase at higher pH. The partition to the PEG phase is strongly favoured in systems with larger tie-line lengths (i.e. systems with higher polymer concentrations). The molecular weight of PEG is important since the partition coefficient (K) of GFP gradually decreases with increasing PEG size, from K ca. 300-400 for PEG 400 to K equal to 1.19 for PEG 8000. A separation process was developed where GFP was separated from a homogenate in two extraction steps: the GFP is first partitioned to the PEG phase in a PEG 3000/NaPA 8000 system containing 3 wt% Na2SO4, where the K value of GFP was 8. The GFP is then re-extracted to a salt phase formed by mixing the previous top-phase with a Na2SO4 solution. The K-value of GFP in this back-extraction was 0.22. The total recovery based on the start material was 74%. (c) 2008 Elsevier B.V. All rights reserved.
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BACKGROUND: Purification of a-toxin produced by Clostridium perfringens type A in aqueous two-phase systems (ATPS) was studied with a full two-level factorial design on two factors (concentrations of 8000 g mol(-1) PEG and phosphate salt at pH 8.0), to estimate the influence of these factors on the purification results. RESULTS: The partition coefficient (K), purification factor (PF) and activity yield (Y) were strongly influenced by the PEG and phosphate concentrations. Raising the levels of the two factors increased these responses. The highest purification factor (5.7) was obtained with PEG and phosphate concentrations of 17.5% and 15%, respectively. CONCLUSION: These results support the proposal that polymer excluded volume and hydrophobic interactions are the factors that drive the alpha-toxin in PEG/phosphate aqueous two-phase systems. (c) 2008 Society of Chemical Industry
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In this work, we take advantage of association rule mining to support two types of medical systems: the Content-based Image Retrieval (CBIR) systems and the Computer-Aided Diagnosis (CAD) systems. For content-based retrieval, association rules are employed to reduce the dimensionality of the feature vectors that represent the images and to improve the precision of the similarity queries. We refer to the association rule-based method to improve CBIR systems proposed here as Feature selection through Association Rules (FAR). To improve CAD systems, we propose the Image Diagnosis Enhancement through Association rules (IDEA) method. Association rules are employed to suggest a second opinion to the radiologist or a preliminary diagnosis of a new image. A second opinion automatically obtained can either accelerate the process of diagnosing or to strengthen a hypothesis, increasing the probability of a prescribed treatment be successful. Two new algorithms are proposed to support the IDEA method: to pre-process low-level features and to propose a preliminary diagnosis based on association rules. We performed several experiments to validate the proposed methods. The results indicate that association rules can be successfully applied to improve CBIR and CAD systems, empowering the arsenal of techniques to support medical image analysis in medical systems. (C) 2009 Elsevier B.V. All rights reserved.
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Pinheiros River (Brazil) plays a pivotal role in supplying water to Billings Reservoir, which presents multiple uses (human drinking, energy generation, irrigation, navigation, fishing and leisure) An intense monitoring program was performed during the years 2007 and 2008 to find out whether on site flotation is a feasible solution or not for improving the water quality of this urban river, attenuating the pollutants load caused by the water pumping to the reservoir (approximately 10 m(3)s(-1)) The monitoring of 18 variables (13,429 laboratorial analysis during the period of 490 days), suggested that despite the convenience of the on site approach for water treatment, especially for rivers located in fully urbanized areas, the flotation system is not enough itself to recover Pinheiros River water quality, given the several constraints that apply Total phosphorus removal was high in percentage terms (about 90%), although the remaining concentrations were not so low (mean of 0 05 mg L(-1)) The removal efficiency of some variables was insufficient, leading to high final mean concentrations of metals [e g aluminium (0 29 mg L(-1)), chromium (0 02 mg L(-1)) and iron (1 1 mg L(-1))] as well as nitrogen-ammonia (25 8 mg L(-1)) and total suspended solids (18 mg L(-1)) in the treated water
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The deterpenation of bergamot essential oil can be performed by liquid liquid extraction using hydrous ethanol as the solvent. A ternary mixture composed of 1-methyl-4-prop-1-en-2-yl-cydohexene (limonene), 3,7-dimethylocta-1,6-dien-3-yl-acetate (linalyl acetate), and 3,7-dimethylocta-1,6-dien-3-ol (linalool), three major compounds commonly found in bergamot oil, was used to simulate this essential oil. Liquid liquid equilibrium data were experimentally determined for systems containing essential oil compounds, ethanol, and water at 298.2 K and are reported in this paper. The experimental data were correlated using the NRTL and UNIQUAC models, and the mean deviations between calculated and experimental data were lower than 0.0062 in all systems, indicating the good descriptive quality of the molecular models. To verify the effect of the water mass fraction in the solvent and the linalool mass fraction in the terpene phase on the distribution coefficients of the essential oil compounds, nonlinear regression analyses were performed, obtaining mathematical models with correlation coefficient values higher than 0.99. The results show that as the water content in the solvent phase increased, the kappa value decreased, regardless of the type of compound studied. Conversely, as the linalool content increased, the distribution coefficients of hydrocarbon terpene and ester also increased. However, the linalool distribution coefficient values were negatively affected when the terpene alcohol content increased in the terpene phase.
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Soybean oil can be deacidified by liquid-liquid extraction with ethanol. In the present paper, the liquid-liquid equilibria of systems composed of refined soybean oil, commercial linoleic acid, ethanol and water were investigated at 298.2 K. The experimental data set obtained from the present study (at 298.2 K) and the results of Mohsen-Nia et al. [1] (at 303.2 K) and Rodrigues et al. [2] (at 323.2 K) were correlated by applying the non-random two liquid (NRTL) model. The results of the present study indicated that the mutual solubility of the compounds decreased with an increase in the water content of the solvent and a decrease in the temperature of the solution. Among variables, the water content of the solvent had the strongest effect on the solubility of the components. The maximum deviation and average variance between the experimental and calculated compositions were 1.60% and 0.89%, indicating that the model could accurately predict the behavior of the compounds at different temperatures and degrees of hydration. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
Liquid-liquid equilibrium experimental data for refined sunflower seed oil, artificially acidified with commercial oleic acid or commercial linoleic acid and a solvent (ethanol + water), were determined at 298.2 K. This set of experimental data and the experimental data from Cuevas et al.,(1) which were obtained from (283.2 to 333.2) K, for degummed sunflower seed oil-containing systems were correlated using NRTL and UNIQUAC models with temperature-dependent binary parameters. The deviation between experimental and calculated compositions presented average values of (1.13 and 1.41) % for NRTL and UNIQUAC equations, respectively, indicating that the models were able to correctly describe the behavior of compounds under different temperature and solvent hydration.
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Document engineering is the computer science discipline that investigates systems for documents in any form and in all media. As with the relationship between software engineering and software, document engineering is concerned with principles, tools and processes that improve our ability to create, manage, and maintain documents (http://www.documentengineering.org). The ACM Symposium on Document Engineering is an annual meeting of researchers active in document engineering: it is sponsored by ACM by means of the ACM SIGWEB Special Interest Group. In this editorial, we first point to work carried out in the context of document engineering, which are directly related to multimedia tools and applications. We conclude with a summary of the papers presented in this special issue.
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Reusable and evolvable Software Engineering Environments (SEES) are essential to software production and have increasingly become a need. In another perspective, software architectures and reference architectures have played a significant role in determining the success of software systems. In this paper we present a reference architecture for SEEs, named RefASSET, which is based on concepts coming from the aspect-oriented approach. This architecture is specialized to the software testing domain and the development of tools for that domain is discussed. This and other case studies have pointed out that the use of aspects in RefASSET provides a better Separation of Concerns, resulting in reusable and evolvable SEEs. (C) 2011 Elsevier Inc. All rights reserved.