Flooding is a truly ubiquitous problem. Today, it puts an estimated 1.81 billion people at risk. Floods particularly affect coastal cities, where it is expected that the damage associated with ...inundations exceed the staggering value of USD 50 billion by 2050. Indeed, the risk associated with flooding in coastal cities is increasing due to three unequivocal trends: growing population in large urban centres, sea level rise, and increased intensity of extreme weather events. Planning and implementation of storm drainage systems in large cities is a complex, long, and expensive process. Typically, the effective lifespan of storm drainage systems may extend to nearly a century. Accordingly, such systems should be designed for the future, not the present. Addressing these important challenges, the paper evaluates flood risks in the coastal city of Maputo, in Mozambique. Results show that, although downtown Maputo is not particularly exposed to compound flooding, accounting for rainfall-tide events is essential to understand flooding in the area and evaluating the performance of the storm drainage system.
The influence of pulp carryover on the efficiency of the xylanase (X) treatment of industrial unbleached and oxygen-delignified eucalypt kraft pulps (A1 and A2 pulps, with kappa number (KN) values of ...16 and 10, respectively), collected at the same pulp mill, was studied regarding the consumption of bleaching chemicals and pulp bleachability. Another non-oxygen-delignified eucalyptus kraft pulp of KN 13 was received after the extended cooking from a different pulp mill (pulp B). The assays were performed with both lab-washed (carryover-free) and unwashed (carryover-rich) pulps. Both lab-washed and unwashed pulps with carryover were subjected to X treatment, the former being demonstrating considerably higher ClO
2
savings than the pulps containing carryover. The savings of bleaching reagents were higher when the X stage was applied to the A1 pulp than to the A2 pulp. This advantage of A1 pulp, however, was not confirmed when using unwashed pulps. In contrast, the gains obtained from the X treatment of unwashed pulp A2 were practically as high as those observed for the lab-washed A2 pulp. Furthermore, a similar effect in X stage was recorded for unwashed pulps having close KN: oxygen-delignified A2 pulp and non-oxygen-delignified B pulp. The results suggest that pulp carryover and initial pH were the key factors relating to the effectiveness of X treatment. The application of X treatment to the A2 unwashed pulp (after the oxygen stage) not only saved 20% of the ClO
2
and 10% of the sodium hydroxide, but also improved the brightness stability of the bleached pulp without affecting its papermaking properties.
Key points
•
Xylanase treatment boosts kraft pulp bleaching
•
Pulp carryover hinders the xylanase treatment
•
Nearly 20% of ClO2 and 10% NaOH savings can be reached using xylanase
The implementation of a risk-informed asset management system by a wastewater infrastructure utility requires information regarding the probability and the consequences of component failures. This ...paper focuses on the former, evaluating the performance of artificial intelligence tools, namely artificial neural networks (ANNs) and support vector machines (SVMs), in predicting the structural condition of sewers. The performance of these tools is compared with that of logistic regression on the case study of the wastewater infrastructures of SANEST — Sistema de Saneamento da Costa do Estoril (Costa do Estoril Wastewater System). The uncertainty associated to ANNs and SVMs is quantified and the results of a trial and error approach and the use of optimization algorithms to develop SVMs are compared. The results highlight the need to account for both the performance and the uncertainty in the process of choosing the best model to estimate the sewer condition, since the ANNs present the highest average performance (78.5% correct predictions in the test sample) but also the highest dispersion of performance results (73% to 81% correct predictions in the test sample), whereas the SVMs have lower average performance (71.1% without optimization and 72.6% with the parameters optimized using the Covariance Matrix Adaptation Evolution Strategy) but little variability.
•The structural condition of sewers is modeled using LR, ANNs and SVMs.•The CMA-ES is used to optimize the support vector machine models.•The variability of the data-based model performance is quantified.•The ANN models obtained the highest performance and uncertainty.•The balance of performance and variability in the model selection is discussed.
•Sparse response surface for reliability as a robust alternative to kriging methods.•Reduction of problem dimensionality using a variable screening procedure.•Optimized and sequential space-filling ...strategy on a promising region of interest.•Combination of a criteria-based stepwise procedure with a weighted regression.•Percentile bootstrap confidence interval on reliability estimates.
In the scope of infrastructure risk assessment, structural reliability analysis leads to a challenging problem in order to deal with conflicting objectives: accurate estimation of failure probabilities and computational efficiency. Since the application of classical reliability methods is limited and often leads to a prohibitive computational cost, metamodeling techniques (e.g. polynomial chaos, kriging, response surface methods (RSM), etc.) have been widely used. Nevertheless, existing RSM present limitations handling with highly non-linear limit states, large-scale problems and approximation error. To overcome these problems, this paper describes a cutting-edge response surface algorithm covering the following issues: (i) dimensionality reduction by a variable screening procedure; (ii) definition of a promising search domain; (iii) initial experimental design based on an optimized space-filling scheme; (iv) model selection according to a stepwise regression procedure; (v) model validation by a cross-validation approach; (vi) model fitting using a double weighted regression technique; (vii) sequential sampling scheme by exploring a defined region of interest; (viii) confidence interval of reliability estimates based on a bootstrapping technique. With the aim of proving its efficiency, a wide collection of six illustration examples, concerning both analytical and FE-based problems, was selected. By benchmarking obtained results with literature findings, proposed method not only outperforms existing RSM, but also provides a powerful alternative to the use of other metamodeling techniques.
A
bstract
We study the phase diagram of 5-dimensional SU(2) Yang-Mills theory on the lattice. We consider two extensions of the fundamental plaquette Wilson action in the search for the continuous ...phase transition suggested by the 4 +
ϵ
expansion. The extensions correspond to new terms in the action:
i
) a unit size plaquette in the adjoint representation or
ii
) a two-unit sided square plaquette in the fundamental representation. We use Monte Carlo to sample the first and second derivative of the entropy near the confinement phase transition, with lattices up to 12
5
. While we exclude the presence of a second order phase transition in the parameter space we sampled for model
i)
, our data is not conclusive in some regions of the parameter space of model
ii)
.
Abstract The TyG index was evaluated as a surrogate method for estimation of insulin resistance (IR). TyG index correlated with adiposity, metabolic and atherosclerosis markers related to IR and ...presented a moderate degree of agreement with hyperglycemic clamp. TyG index represents an accessible tool for assessment of IR in clinical practice.
In this work, the corrosion protection of 316L steel was promoted by an electro‐synthesized polymer obtained from the technical cashew nutshell liquid (t‐CNSL). Spectroscopic techniques confirmed the ...polymer formation. The polymer was dispersed in the ethyl acetate solvent and used to form coatings on 316L steel substrates. The coated samples were subjected to electrochemical tests in a saline environment. The coated electrode with poly(t‐CNSL) polymer was exposed to the corrosive medium for 24 days, and superior corrosion protection was observed compared with the uncoated sample. The open circuit potential measurements showed that the coated sample possessed a more positive corrosion potential when compared with the uncoated substrate. The electrochemical impedance spectroscopy results indicated that the coated electrode's polarization resistance (Rp) recorded ~1.0 MΩ cm2 after 24 days of exposure. A decrease in polarization resistance was observed with the exposure time due to the presence of micropores in the t‐CNSL coating. The polarization curves exhibited that the coated electrode with poly(t‐CNSL) has lower corrosion current density and less negative corrosion potential than the uncoated steel electrode. Therefore, t‐CNSL favors the manufacture of thin poly(t‐CNSL) coatings for corrosion protection purposes besides being a low‐cost material.
A new polymer was obtained from the technical cashew nutshell liquid (t‐CNSL). The poly(t‐CNSL) is synthesized through the electrosynthesis method. The polymer is low‐cost, thermally stable, and easy to prepare. Poly(t‐CNSL) coating provides corrosion protection of steel in saline solution.
Loss of pulp yield and increased chemical oxygen demand (COD) of the effluent are the main constraints to the wider application of xylanase-assisted bleaching of hardwood kraft pulps. The commercial ...utilization of released pulp xylan could, in turn, increase the attractiveness of the enzymatic technology. This study thus aimed to evaluate the products derived from xylan in the effluent from the treatment of oxygen-delignified eucalypt kraft pulp with a commercial endoxylanase using nanofiltration as a purification step. Pulp enzymatic treatments resulted in the release of xylo-oligosaccharides (XOS), the most abundant being xylotriose and xylotetraose. The obtained xylan-derived solutions were purified by a two-step membrane nanofiltration aiming to purify and concentrate XOS possessing commercial value as prebiotics. Although the effluent from the xylanase treatment of pulp appears to have potential as a source of XOS with prebiotic activity, the future implementation of a membrane filtration system to obtain these high-purity products will require further refinements.
Over the last few decades, journalism in Portugal has undergone a series of changes in both its practice and its conditions. This reconfiguration has been reinforced by the noticeable rise in layoffs ...and fixed-term contracts, particularly after the implementation of an austerity program over the last few years. This has led many journalists to abandon their job, either voluntarily or otherwise. The present article aims to analyse these trends through the socio-professional trajectories of ex-journalists, seeking to understand what led to the end of their careers, what came after, and what is their current outlook on journalism.
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