Search results for "Uncertainty analysis"
showing 10 items of 91 documents
Virtual Instruments: Uncertainty Evaluation in the Presence of Electromagnetic Interferences
2007
The electromagnetic interferences can influence the performances of a virtual instrument; consequently, in a generic measurement performed by using these instruments, the related uncertainty values can increase. In the paper, we report the results of various experimental tests performed with the aim to check if and how the radiated and/or conducted disturbances affect the instruments' characteristics and, in particular, the single uncertainty sources. Starting from these results and applying an already proposed method for the uncertainty estimation in the measurements performed by means of virtual instruments, it is possible to take into account and to evaluate the contribute of the electro…
Error and Uncertainty Analysis of Non-Uniform Residual Stress Evaluation by Using the Ring-Core Method
2016
Like other mechanical methods used for the residual stress evaluation on a generic structural component, the Ring-Core Method (RCM) is potentially subjected to various error sources that in some particular experimental conditions can lead to significant errors and/or uncertainties on the computed residual stresses. The accuracy of the residual stresses computed by the RCM can be improved by a proper error analysis that allows the user to correct the systematic errors, as well as to evaluate the remaining stress uncertainty due to the random errors. Therefore, in order to give a contribution to the accuracy of the RCM, in the present work the list of the main error sources is presented and t…
A Monte Carlo Method for the Auto-Evaluation of the Uncertainties in the Analog-to-Digital Conversion-Based Measurements
2004
This paper concerns with the measurement uncertainty estimation in the analog‐to‐digital conversion‐based instruments. By using an ad hoc developed software tool, the Monte Carlo method is applied in order to assess the uncertainties associated with the measurement results, overcoming the possible inapplicability of the pure theoretical approach prescribed in the ISO – “Guide to the Expression of Uncertainty in Measurement”. By implementing the software tool in the measurement instruments, the proposed approach can be utilized in order to make the instrument itself able to auto‐estimate the measurement uncertainties.
Uncertainty related to climate change in the assessment of the DDF curve parameters
2017
In the context of climate change, the evaluation of the parameters of Depth-Duration-Frequency (DDF) curves has become a critical issue. Neglecting future rainfall variations could result in an overestimation/underestimation of DDF parameters and, consequently, of the design storm. In this study, uncertainty analysis was integrated into trend analysis to provide an estimate of trends that cannot actually be rigorously verified. A Bayesian procedure was suggested for the updating of DDF curve parameters and to evaluate the uncertainty related to their assessment. The proposed procedure also allowed identification of the years of a series that contributed most to the overall uncertainty relat…
Greenhouse Gas Emissions from Wastewater Treatment Plants on a Plantwide Scale: Sensitivity and Uncertainty Analysis
2016
This paper presents the sensitivity and uncertainty analysis of a mathematical model for greenhouse gas emission (GHG) and energy consumption assessment in wastewater treatment plants. A sensitivity analysis was carried out (using two different methods) to determine which model factors have the greatest effect on the predicted values of the GHG production. Further, an uncertainty analysis was carried out to quantify the uncertainty of the key model outputs, such as carbon dioxide production from activated sludge treatment. The results show that influent fractionation factors, which characterize influent composition, have an important role on direct and indirect GHGs production and emission.…
Integrated urban water modelling with uncertainty analysis
2006
In the last twenty years, the scientific world has paid particular care towards the problems that involve the environment. Accordingly, several researches were developed to describe phenomena that take place during both wet and dry periods and to increase the knowledge in this field. In particular, attention was addressed towards the problems linked with receiving water body pollution because of the impact of rain water in the urban environment. In order to obtain a good description of the problem, it is important to analyse both quantity and quality aspects connected with all the transformation phases that characterise the urban water cycle. Today, according to this point, integrated model…
Identifiability analysis for receiving water body quality modelling
2009
In urban drainage, new computational possibilities have supported the development of new integrated approaches aimed at joint water quantity and quality analysis of the whole urban drainage system. Although the benefit of an integrated approach has been widely demonstrated, to date, several aspects prevent its applicability such as scarce availability of field data if compared with model complexity. These aspects sometimes prevent the correct estimation of parameters thus leading to large uncertainty in modelling response. This is a typical parameter identifiability problem that is discussed in the present paper evaluating the effect of identifiability procedures in increasing operator conf…
Uncertainty and sensitivity analysis for reducing greenhouse gas emissions from wastewater treatment plants.
2020
Abstract This paper presents the sensitivity and uncertainty analysis of a plant-wide mathematical model for wastewater treatment plants (WWTPs). The mathematical model assesses direct and indirect (due to the energy consumption) greenhouse gases (GHG) emissions from a WWTP employing a whole-plant approach. The model includes: i) the kinetic/mass-balance based model regarding nitrogen; ii) two-step nitrification process; iii) N2O formation both during nitrification and denitrification (as dissolved and off-gas concentration). Important model factors have been selected by using the Extended-Fourier Amplitude Sensitivity Testing (FAST) global sensitivity analysis method. A scenario analysis h…
Greenhouse gases from membrane bioreactors: Mathematical modelling, sensitivity and uncertainty analysis
2017
In this study a new mathematical model to quantify greenhouse gas emissions (namely, carbon dioxide and nitrous oxide) from membrane bioreactors (MBRs) is presented. The model has been adopted to predict the key processes of a pilot plant with pre-denitrification MBR scheme, filled with domestic and saline wastewater. The model was calibrated by adopting an advanced protocol based on an extensive dataset. In terms of nitrous oxide, the results show that an important role is played by the half saturation coefficients related to nitrogen removal processes and the model factors affecting the oxygen transfer rate in the aerobic and MBR tanks. Uncertainty analysis showed that for the gaseous mod…
Global sensitivity and uncertainty analysis of a microalgae model for wastewater treatment.
2022
The results of a global sensitivity and uncertainty analysis of a microalgae model applied to a Membrane Photobioreactor (MPBR) pilot plant were assessed. The main goals of this study were: (I) to identify the sensitivity factors of the model through the Morris screening method, i.e. the most influential factors; (II) to calibrate the influential factors online or offline; and (III) to assess the model's uncertainty. Four experimental periods were evaluated, which encompassed a wide range of environmental and operational conditions. Eleven influential factors (e.g. maximum specific growth rate, light intensity and maximum temperature) were identified in the model from a set of 34 kinetic pa…