Search results for " modeling"
showing 10 items of 2411 documents
Using Macroelement Content to Characterize Surficial Water Quality of Artificial Reservoirs
2021
Abstract The quality of surface waters in the territory of Poland, despite the implemented remedial measures, is mostly classified as bad. This article presents the results of research on the composition of water macroelements in 24 artificial reservoirs located in Opole province (southern Poland), searching for the reasons behind their pollution. Concentrations of the anions F−, Cl−, Br−, NO2−, NO3−, PO43− and SO42− and cations Na+, NH4+, K+, Mg2+ and Ca2+ were taken into account. An analysis of seasonal changes was carried out and, on the example of a dam reservoir (Turawa Big Reservoir), a multi-point analysis of the distribution of ion concentrations in water at the reservoir surface w…
Distribution of Heavy Metals in Marine Sediments of Palermo Gulf (Sicily, Italy)
2008
Concentrations of Cr, Cu, Hg, Pb and Zn have been measured, by atomic absorption spectrophotometry, in the fine fraction (<63 μm) of surface sediments collected in 30 sites in the Palermo Gulf (Sicily, Italy) in order to assess the levels and the spatial distribution of these elements. Enrichment factors calculated with respect to clean areas have been considered to discriminate between levels due to background or to pollution contributions. The sampling stations, which form a grid inside these areas, are characterized by geographic proximity and by the presence of pollution sources. Ratio matching technique along with hierarchical clustering, minimum spanning tree and principal component a…
Towards A New Decision Support System for Design, Management and Operation of Wastewater Treatment Plants for the Reduction of Greenhouse Gases Emiss…
2015
The increasing attention paid to the environment has led to a reduction in the emissions from wastewater treatment plants (WWTPs). Moreover, the increasing interest in the greenhouse gas (GHG) emissions from WWTPs suggests that we reconsider the traditional tools used for designing and managing WWTPs. Indeed, nitrous oxide, carbon dioxide and methane can be emitted from wastewater treatment, significantly contributing to the greenhouse gas (GHG) footprint. The reduction of energy consumption as well as GHG emission are of particular concern for large WWTPs which treat the majority of wastewater in terms of both volume and pollution load. Nowadays, there is an increasing need to develop new …
A Microstructural Model for Micro-Cracking in Piezoceramics
2018
Piezoelectric ceramics are employed in several applications for their capability to couple mechanical and electrical fields, which can be advantageously exploited for the implementation of smart functionalities. The electromechanical coupling, which can be employed for fast accurate micro-positioning devices, makes such materials suitable for application in micro electromechanical systems (MEMS). However, due to their brittleness, piezoceramics can develop damage leading to initiation of micro-cracks, affecting the performance of the material in general and the micro-devices in particular. For such reasons, the development of accurate and robust numerical tools is an important asset for the…
TOWARD A DESIGN METHOD FOR METAL-COMPOSITE CO-CURED JOINT BASED ON THE G-SIFs
2013
Abstract In this work, a systematic study of the singular stress field in the zone where the interface intersects the free edge surfaces of bonded metal-composite co-cured joints, has been performed. The obtained theoretical, numerical and experimental results have permitted to detect the relationships between the joint configuration and the singular stress field, as well as to implement a new design method based on the so called generalised stress intensity factors. Such a proposed method allows the user to predict the static strength of a generic metal-composite co-cured joint, vs. the main influence parameters as the elastic modulus of the coupled materials, the overlap length, the taper…
Polynomial Fuzzy Models for Nonlinear Control: A Taylor Series Approach
2009
Classical Takagi-Sugeno (T-S) fuzzy models are formed by convex combinations of linear consequent local models. Such fuzzy models can be obtained from nonlinear first-principle equations by the well-known sector-nonlinearity modeling technique. This paper extends the sector-nonlinearity approach to the polynomial case. This way, generalized polynomial fuzzy models are obtained. The new class of models is polynomial, both in the membership functions and in the consequent models. Importantly, T-S models become a particular case of the proposed technique. Recent possibilities for stability analysis and controller synthesis are also discussed. A set of examples shows that polynomial modeling is…
Predictors of mental health during the COVID-19 pandemic in older adults: the role of socio-demographic variables and COVID-19 anxiety
2021
The objective of this study was to evaluate factors related to the mental health of Peruvian older adults during the COVID-19 pandemic. The study had a cross-sectional and observational design. A total of 274 older adults in Lima, Peru (Mage = 67.86) filled out a sociodemographic survey, the Coronavirus Anxiety Scale, Mental Health Inventory-5, Patient Health Questionnaire-2 item, and Generalized Anxiety Disorder Scale. A Structural Equation Model (SEM) was estimated to test an a priori model that relates the sociodemographic variables, COVID-19 Anxiety, psychological well-being, anxiety and depression. The model fit indices indicated a good fit to the data. The socio-demographic variables …
Pharmacokinetic Characterization and External Evaluation of a Quantitative Framework of Sublingual Buprenorphine in Patients with an Opioid Disorder …
2020
Background: The aim of this analysis was to characterize the pharmacokinetics (PK) of sublingual buprenorphine (BUP) and its metabolites (buprenorphine glucuronide
Modeling recurrent distributions in streams using possible worlds
2015
Discovering changes in the data distribution of streams and discovering recurrent data distributions are challenging problems in data mining and machine learning. Both have received a lot of attention in the context of classification. With the ever increasing growth of data, however, there is a high demand of compact and universal representations of data streams that enable the user to analyze current as well as historic data without having access to the raw data. To make a first step towards this direction, we propose a condensed representation that captures the various — possibly recurrent — data distributions of the stream by extending the notion of possible worlds. The representation en…
How pre-service teachers perceive their 21st-century skills and dispositions : A longitudinal perspective
2021
Research-based discussions about 21st-century skills are currently needed; 21st-century skills refer to skills that today's students are expected to possess for successful future careers. The ways students perceive these skills or what kind of dispositions they have in this regard are significant. This paper provides an overview of the development of pre-service teachers' perceived 21st-century skills and dispositions. The quantitative data was collected in three phases during 2014, 2015, and 2016 at three Finnish universities. The number of respondents at each measurement point varied from 209 to 267. Data were analysed using latent growth curve modeling. The study focuses on students' per…