Robust Simulation of Counterflow Moving Bed Dryers

Abstract

In this work, a robust and accurate strategy for simulating counterflow moving bed dryers is presented. A complete pseudo-transient phenomenological model for the process has been developed and the variable time is used as a continuation parameter. The desired solution is the final steady-state reached by the model. The code DASSL is used to perform the integration of the differential algebraic equation system and consistent initialization is achieved via a direct technique. The computational effort is surprisingly small comparing to those reported in the literature. Reasonable concordance between simulated and experimental results has been observed even though the mathematical model contains no adjustable parameters. Convergence problems have not been observed for all tested operating conditions, including those pointed by other authors as particularly difficult. The mathematical tool built is capable of making accurate predictions about the behavior of the equipment in affordable computing time and hence this constitutes an invaluable tool to study counterflow moving bed drying.     

Multi-stage modeling using fuzzy multi-criteria feature selection to improve survival prediction of ICU septic shock patients

In many binary medical classification problems, the cost of misclassifying one category is higher than the other, and in these applications it is desirable to employ a classifier with selective sensitivity or specificity. This work explores the utility of a fuzzy multi–criteria function for performance evaluation during knowledge–based medical classification and prediction. The method presented here uses fuzzy optimization to combine the sensitivity, specificity, and accuracy of classification as goals in a single objective function. This approach is used to assign flexible goals, which can be used to maximize the outcome in terms of each one of the goals. The proposed approach significantly increases the sensitivity and the specificity while maintaining or increasing accuracy. The versatility of the method is further exploited in a multi-model approach, using individual structures of multi-objective optimization of sensitivity and specificity separately, and then combining their outcomes through a decision-making module. Among various medical benefits derived from applying this technique, the divergent feature sets selected by high sensitivity and specificity models lend insight into factors more integrally connected to what causes risk of death for patients.     

Changes in Coupled Vibration Frequencies and Modes of Wall-Cavity Systems Induced by Stiffness Variation in the Structure

Problems of fluid structure interactions are governed by a set of fundamental parameters. This work aims at showing through simple examples the changes in natural vibration frequencies and mode shapes for wall-cavity systems when the structural rigidity is modified. Numerical results are constructed using ANSYS software with triangular finite elements for both the fluid （2D acoustic elements） and the solid （plane stress） domains. These former results are compared to proposed analytical expressions, showing an alternative benchmark tool for the analyst. Very rigid wall structures imply in frequencies and mode shapes almost identical to those achieved for an acoustic cavity with Neumann boundary condition at the interface. In this case, the wall behaves as rigid and fluid-structure system mode shapes are similar to those achieved for the uncoupled reservoir case.     

Territorial development in the Cape Verde archipelago under the Estado Novo dictatorship (1953–1974)

Despite Portugal's neutrality in the Second World War (1939–1945), the subsequent new world order meant that the Portuguese Government felt obliged to revise its overseas policies. A new regional awareness could be seen in the Six-Year National Development Plans launched by Estado Novo from 1953 until the revolution of 1974. The territory and its strategic potential were emphasized in the context of national policies of overseas urbanization. Interventions in Cape Verde are visible particularly in the First Development Plan, which was based on equipping the province's public facilities. The methodology of intervention involved setting up missions aimed at planning a set of specific public works which were essential to the development of existing settlements. A sharp increase in the development of the territory through the work of specialized brigades took place in the Third Development Plan, when a set of public works on road, hydraulic and electricity networks was undertaken. The planning of infrastructures that was undertaken in these years was essential to the development of the archipelago and the resulting regional and urban land-use planning of the various islands.     

Methanol Selective Oxidation to Formaldehyde over Iron-Molybdate Catalysts

This review deals with the important industrial reaction of formaldehyde manufacture by methanol oxidation over iron molybdate catalysts. Detailed reference is made to the used catalyst, preparation techniques (coprecipitation, sol-gel like, mechanical mixing, etc.) including unsupported and supported catalysts, promoters and characterization methods. The controversial active phase assignment (stoichiometric versus Mo rich iron molybdate) is discussed. The proposed reaction mechanisms and kinetic laws for the main and side reactions are examined. The catalyst deactivation processes are reviewed and the role of Mo excess on these processes is underlined. Finally conclusions and perspectives are presented.     

Behavioral Changes in Workers of the Leaf-Cutting Ant Atta sexdens rubropilosa Induced by Chemical Components of Eucalyptus maculata Leaves

The response of Atta sexdens rubropilosa Forel workers to essential oils, epicuticular wax and hexane, dichloromethane, ethyl acetate, and methanol extracts of Eucalyptus maculata was evaluated. Hexane extracts of E. maculata interfered with the recognition mechanism among workers. The main active compounds identified from this plant were the sesquiterpenes elemol and beta-eudesmol. These compounds may be responsible for the resistance of this species to ant attack.     

Energy spectrum of an electron confined in the hexagon-shaped quantum well

Considering the hexagonal-shaped quantum-scale formations on the surface of thin semiconductor films, a methodology was developed to obtain the analytical solution of the Schrdinger equation when impenetrable walls of a quantum well are treated as mirrors. The results obtained allowed the calculation of the space probability distributions and the energy spectrum of the particle confined in a hex-agonal-shaped well.     

Reference Material for the Determination of Polychlorodibenzo-<Emphasis Type="Italic">p</Emphasis>-dioxins,Polychlorodibenzo-furans,and Polychlorinated Biphenyls in Fish: Production Process,Homogeneity, and Stability

The presence of dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in food is an important consideration for food safety, especially in fish matrices that are susceptible to bioaccumulation of those compounds from marine environments. In this context, the production of a reference material (RM) for this analytical scope is of great importance for ensuring the reliability of the results generated by monitoring programs. A lyophilized material was produced by spiking tilapia fillets with 29 compounds, and the material was evaluated based on the potential for using it as a certified reference material (CRM) or in proficiency testing (PT) schemes. A pilot experiment was performed to evaluate the incorporation of the analytes in tilapia fillets using standards prepared in nonane and in fish oil. The process yield was approximately 16% for both conditions, but higher mean recoveries were achieved with fish oil. The tilapia fillets were processed, and a portion of this bulk was spiked and then homogenized. The spiked and unspiked portions were frozen prior to lyophilization. Each freeze-dried portion was homogenized and sieved, and then, the portions were mixed, packed, and stored under refrigeration. The material was considered homogeneous for all analytes based on the criteria established for PT. Of the tested analytes, 27 were found to be stable in the short-term design (p > 0.05) when the material was kept at 45 ± 2 °C for 9 days. Long-term stability was evaluated at 2, 4, 6, and 8 months, and 22 of the analytes were found to be stable through up to 4 months of storage based on the criteria defined in references related to both the production of CRM and PT. The contributions of the homogeneity and stability in the short- and long-term uncertainties were estimated and indicated the adequacy of the material for use as a reference for trueness experiments.     

Bootstrap interval with application in environmental monitoring

ABSTRACT

Environmental research data usually present high variability because of the presence of outlier values. This study sought to apply the interval bootstrap method, as compared to Chebyshev’s Theorem, for the statistical assessment of environmental data with anomalous values. The results obtained showed that: (a) the bootstrap method is an excellent alternative in the assessment of environmental data with outliers; (b) the method percentile bootstrap (Boot-perc-s) presented the lower interval amplitude to the concentrations of ²²⁶Ra, and (c) Chebyshev’s Theorem presented the highest interval amplitude for the concentration of ²²⁶Ra.     

Strain-specific polyketide synthase genes of Aspergillus niger

In silico comparison of 34 putative pks genes in Aspergillus niger strain CBS 513.88 versus A. niger strain ATCC 1015 genome revealed significant nucleotide identity (>95% covering a minimum of 99% of the gene sequence) for 31 of these genes (approximately 91%). A. niger CBS 513.88 harbors three putative pks genes (An01g01130, An11g05940, and An15g07920), for which nucleotide identity was not found in A. niger ATCC 1015. To compare the results of the in silico analysis with the in vivo situation, experimental data were obtained for a large number of A. niger strains obtained from different substrates and geographical regions. Three putative pks genes that were found to be variable between the two A. niger strains using bioinformatics tools were in fact strain-specific genes based on experimental data. The PCR amplification signals for the An01g01130, An11g05940, and An15g07920 pks genes were detected in only 97%, 71%, and 26% of the strains, respectively. Southern blot analyses confirmed the PCR data. Because one of the strain-specific pks genes (An15g07920) is located in a putative ochratoxin cluster, we focused our investigation on that region. We assessed the ochratoxin production capability of the 119 A. niger strains and found a positive association between the presence of this pks gene and the capability of the respective strain to produce ochratoxin.