1,721,202 research outputs found
Pre-conditioning approach to Bayesian Decision Network for water quality sensors positioning in urban drainage systems
No full textIn the last decades, the growth of mini- and micro-industry in urban areas has
produced an increase in the frequency of xenobiotic polluting discharges in drainage
systems. Such pollutants are usually characterized by low removal efficiencies in urban
wastewater treatment plants and they may have an acute or cumulative impact on
environment. In order to facilitate early detection and efficient containment of the illicit
intrusions, the present work aims to develop a decision-support approach for positioning
the water quality sensors. It is mainly based on the use of a decision-making support of
the BDN type (Bayesian Decision Network), specifically looking soluble conservative
pollutants, such as metals. In the application and result section the methodology is tested
on two sewer systems, with increasing complexity: a literature scheme from the SWMM
manual and a real combined sewer
On a dynamic nonsubstitution theorem and other issues in Burgstaller's ``Property and prices''
No full textItalian prisoners who died during and after the First World War: A quantitative assessment
No full textThe number of Italian military prisoners who died in enemy hands stands, according to the Italian historiography on the First World War, at 100,000 or more. In this paper, we offer an alternative estimate of the number of deaths using both individual and aggregate data. The reconstruction distinguishes between soldiers who died in captivity and soldiers who died as a consequence of captivity during and after the war. The results demonstrate that the number 100,000 is too high. The correct number would be, for the period from 25 May 1915 to 31 December 1925, above 57,000 and probably lower than 73,000
Quantification of the uncertainty contributions for a complex water quality model
No full textThe quantification of uncertainty in integrated urban drainage water quality models is of paramount
interest. Indeed, the assessment of the reliability of the model results for complex water quality models
is useful for understanding the significance of the results. However, the state of knowledge regarding
uncertainties in urban drainage models is poor. In the case of integrated urban drainage water quality
models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating
sewer system, wastewater treatment plant and receiving water body), the uncertainty produced in one
sub-model propagates to the following ones depending on the model structure, the estimation of
parameters and the availability and uncertainty of measurements in the different parts of the system.
Uncertainty basically propagates throughout a chain of models in which simulation output from
upstream models is transferred to the downstream ones as input. The overall uncertainty can differ
from the simple sum of uncertainties generated in each sub-model, depending on well-known
uncertainty accumulation problems. The paper presents the quantification of the uncertainty
contributions for an integrated urban drainage model developed in previous studies. Particularly, the
different parts of the quantifiable uncertainty have been assessed and compared by means of the
variance decomposition concept. The integrated model and the methodology for the uncertainty
decomposition have been applied to a complex integrated catchment: the Nocella basin (Italy). The
results showed that the variance decomposition approach can be a powerful tool for uncertainty
analysis but the possible correlation among uncertainty sources should be considered because it can
greatly affect the analysis
La struttura della popolazione militare italiana nel corso della Prima guerra mondiale
No full textThis article analyses the Italian Army’s demographic composition during First World War. The focus is on the number of soldiers employed and their age structure at different stages of the conflict. The work also aims to evaluate the possible consequences of the demographic evolution of the corps on the quality of troops. The average age of Italian soldiers in July 1915 was 23.8 while in October 1918 rose to 27.4. The call to arms of younger and younger soldiers has not been sufficient to balance the mortality of the birth cohorts fighting since the beginning of the conflict and the growing involvement of increasingly older cohorts having as a result the increase in the average age
The Workload of the Italian Military Health Service During the First World War: A Quantitative Assessment
No full textThe article proposes a quantitative evaluation of the workload of the Italian military health service during the First World War. In the Great War, there were unprecedented medical and health care issues. This was a result of the size of armies; the poor living conditions of the soldiers; and the introduction of new weapons. This article reconstructs some quantitative aspects of the Italian military health service in the Great War in terms of both supply (e.g. the number of health structures and medical personnel) and demand (e.g. the soldiers who were injured and who became ill during the conflict)
Uncertainty estimation of a complex water quality model: GLUE vs Bayesian approach applied with Box – Cox transformation
No full textIn urban drainage modelling, uncertainty analysis is of undoubted necessity; however, several methodological aspects need to be clarified and deserve to be investigated in the future, especially in water quality modelling. The use of the Bayesian approach to uncertainty analysis has been stimulated by its rigorous theoretical framework and by the possibility of evaluating the impact of new knowledge on the modelling estimates. Nevertheless, the Bayesian approach relies on some restrictive hypotheses that are not present in less formal methods like GLUE. One crucial point in the application of Bayesian methods is the formulation of a likelihood function that is conditioned by the hypotheses made regarding model residuals. Statistical transformations, such as by the use of the Box–Cox equation, are generally used to ensure the homoscedasticity of residuals but this practice may affect the reliability of the analysis leading to a wrong estimation of the uncertainty. The present paper aims to study the impact of such a transformation considering five cases one of which is the “real” residuals distributions (drawn from available data). The analysis was applied to the Nocella experimental catchment (Italy) which is an agricultural and semi-urbanised basin where two sewer systems, two wastewater treatment plants and a river reach were monitored during both dry and wet weather periods. The results show that the uncertainty estimation is greatly affected by residual transformation and a wrong assumption may also affect the evaluation of model uncertainty. The use of less formal methods always provide an overestimation of modelling uncertainty with respect to Bayesian method but such effect is reduced if a wrong assumption is made regarding the residuals distribution. If residuals are not normally distributed, the uncertainty is over-estimated if Box-Cox transformation is not applied or non calibrated parameter is used
Notes about urban drainage systems in the ancient Rome
No full textThe magnificence of Roman buildings is very well-known from historical books, notes etc.. In contraposition to this, generally speaking, less is known about the majesty of Roman sewer systems in terms of structures, facilities and the very advanced as well as rudimental complexity. The Roman sewers have been over-praised. Indeed, despite their longevity, they ignored basic sanitary principles as well as design rules.
The Roman Empire is in many ways the highest point of sewage management in the ancient world. Famous for public baths and latrines with quite complex engineering, Rome also excelled in the use of covered drains for stormwater and waste-sewage, with some houses directly connected to the drainage system. Water conveyance in large-scale aqueducts was another impressive accomplishment. With the Roman Empire, these technologies were introduced across large geographic parts
Uncertainty in environmental and hydrological mathematical modelling
No full textEngineers are increasingly called to deal with practical problems related to water resources management, risk analysis, environmental engineering and water pollution. Providing a way forward to solve the above questions requires setting up mathematical models that are affected by uncertainty, that in many cases is relevant. In fact, the theories that are employed for providing solutions to engineer’s problems are not exact sciences: even if it is methodologically rigorous, it is incapable of producing precise results, for the presence of inherent randomness that translates in indeterminacy and therefore uncertainty. To cope with uncertainty is a challenge for scientists and practitioners, that requires the application of proper procedures for model identification, parameter calibration, hypothesis testing, model testing (also called model validation) and finally uncertainty assessment. As a matter of fact, uncertainty estimation in hydrological surface and subsurface modelling is today one of the most important subfields of hydrology, according to the numerous contributions presented by the recent scientific literature
La costruzione delle curve di offerta di lungo periodo: Note alla critica di Sraffa alle analisi di equilibrio parziale
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