Search results for "Environmental engineering"

Effects of plant species in a horizontal subsurface flow constructedwetland – phytoremediation of treated urban wastewater withCyperus alternifolius …

2013

Abstract Plant species carry out a series of important biological, chemical and physical processes within a constructed wetland wastewater treatment system and make a significant contribution to wastewater purification. This paper compares two emergent macrophytes – Cyperus alternifolius L. and Typha latifolia L. – planted separately in a pilot horizontal subsurface flow system for the phytoremediation of treated urban wastewater in the West of Sicily (Italy). The total surface area of the three units within the pilot system was 99 m 2 . Six subunits were planted with two species and three subunits were left unplanted as the control. The main aim of the study was to demonstrate that, under …

Typology of inflorescences

1965

A comprehensive analysis of Universal Soil Loss Equation-based models at the Sparacia experimental area

2020

Improving Universal Soil Loss Equation (USLE)‐based models has large interest because simple and reliable analytical tools are necessary in the perspective of a sustainable land management. At first, in this paper, a general definition of the event rainfall‐ runoff erosivity factor for the USLE‐based models, REFₑ = (QR)ᵇ¹(EI₃₀)ᵇ², in which QR is the event runoff coefficient, EI₃₀ is the single‐storm erosion index, and b₁ and b₂ are coefficients, was introduced. The rainfall‐runoff erosivity factors of the USLE (b₁ = 0 and b₂ = 1), USLE‐M (b₁ = b₂ = 1), USLE‐MB (b₁ ≠ 1 and b₂ = 1), USLE‐MR (b₁ = 1 and b₂ ≠ 1), USLE‐MM (b₁ = b₂ ≠ 1), and USLE‐M2 (b₁ ≠ b₂ ≠ 1) can be defined using REFₑ. Then t…

Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain

2011

A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency o…

The use of soil water retention curve models in analyzing slope stability in differently structured soils

2017

Abstract This study analyzes whether and at what rate the parameterization of the Soil Water Retention Curve (SWRC) affects the analysis of shallow slope stability for differently structured unsaturated soils. Advanced empirical or physically-based equations of SWRCs have been proposed in literature to describe soil systems characterized by the so-called bimodal porous domain. In unsaturated soils, SWRC affects the stability assessment in two ways. It influences the resistance properties in terms of shear strengths, which depend on the soil water suction; and it affects the hydrological process modeling (e.g. infiltration) directly influencing soil moisture patterns and indirectly influenci…

Monthly Hydrological Indicators to Assess Possible Alterations on Rivers’ Flow Regime

2018

Assessing potential deviations of the fundamental river basins’ hydrological processes and streamflow characteristics from the “natural trajectory” represents a high-priority objective to understand the biological impact of altered flow regime on river ecosystems. Existing approaches are mainly based on the analysis of daily-based indicators of hydrologic alteration, which requires wide database, including “pre-impact” and “post-impact” daily flow data frequently unavailable. The hydrological modeling is commonly used to face data missing problems or reconstruct natural conditions, even if models, especially at the daily scales, are often complex and computationally intensive. The use of si…

Urban runoff modelling uncertainty: Comparison among Bayesian and pseudo-Bayesian methods

2009

Urban stormwater quality modelling plays a central role in evaluation of the quality of the receiving water body. However, the complexity of the physical processes that must be simulated and the limited amount of data available for calibration may lead to high uncertainty in the model results. This study was conducted to assess modelling uncertainty associated with catchment surface pollution evaluation. Eight models were compared based on the results of a case study in which there was limited data available for calibration. Uncertainty analysis was then conducted using three different methods: the Bayesian Monte Carlo method, the GLUE pseudo-Bayesian method and the GLUE method revised by m…

A novel active contour model for unsupervised low-key image segmentation

2013

Published version of an article in the journal: Central European Journal of Engineering. Also available from the publisher at: http://dx.doi.org/10.2478/s13531-012-0050-0 Unsupervised image segmentation is greatly useful in many vision-based applications. In this paper, we aim at the unsupervised low-key image segmentation. In low-key images, dark tone dominates the background, and gray level distribution of the foreground is heterogeneous. They widely exist in the areas of space exploration, machine vision, medical imaging, etc. In our algorithm, a novel active contour model with the probability density function of gamma distribution is proposed. The flexible gamma distribution gives a bet…

Fundamental Analysis of Triple Layer Area Decoupled Photovoltaic Modules

2015

Masteroppgave fornybar energi- Universitetet i Agder, 2015 The main objective of this work is to analyse the area decoupled triple layer photovoltaic module, by application of voltage matching under AM 1.5 light spectrum. This includes, calculation of detailed balance efficiency, calculation of optimal numbers of cells in each layer to achieve voltage matching comparisons with independently operated triple layer stack. Performance change under various different scenario is also observed. We have used MatLab programing software for all our analysis i.e., plots and calculations. At first we investigated the optimal efficiency of independently operated cells of triple layer stack. Then applyin…

Development and Electrochemical Evaluation of Tape Cast Substrates for SOFC Single Cells

2013

Masteroppgave fornybar energi- Universitetet i Agder, 2013 As a means to reduce the solid oxide fuel cell material cost and make it more adapted to other fuels, titania as a candidate catalyst material has been investigated. A low-cost, high precision, self made tape casting system made it possible to fabricate thin films by the tape casting method. Substrates for SOFC single cells were manufactured through experimentation and optimization of slurry recipes for tape casting. The produced substrates were micro-structural analyzed by using an AFM, and evaluated with the use of EIS. The study shows that it is possible to fabricate standalone titania substrates. And the structural analysis and …