Search results for "Uncertainty"
showing 10 items of 1010 documents
Models of Dynamical Modelling Under Uncertainty
1986
The objective of this work is to modelize the evolution of a Model-System to be adapted to a Random System. This evolution is described by means of the change of a probabilistic function, through deterministic rules and in function of the random responses of the modelized System. This probabilistic function can describe the relative weight of distinct submodels (deterministic or random Systems, with constant or variable stimulus), or the stimulus-response relation in the Model-System (Adaptative Random System). We conclude that the Adaptative Random Model permits a more precise, simple and economical modelling.
Assessment of building energy modelling studies to meet the requirements of the new Energy Performance of Buildings Directive
2020
Abstract The cost optimal method (COM) as applied in the Energy Performance of Buildings Directive (EPBD) uses “non-calibrated deterministic reference buildings (RBs)”. Such RBs are defined with single envelope and equipment parameter values, for which calibration with actual building stock energy performance (EP) is not undertaken. Thus, it is not possible to visualise the effect of uncertainties or diversity in the input parameters on cost-optimal level benchmarks and to verify the choice of RBs. The paper proposes an update to the COM via use of “Probabilistic Bayesian calibrated RBs” to handle uncertainties and produce more realistic cost optimal levels to support policy makers in devis…
Handling epistemic uncertainty in the Fault Tree Analysis using interval valued expert information
2014
Risk Analysis ( RA) is a meaningful process in every industrial context, particularly referring to major hazard plants. In such sites, input reliability data are generally poor so leading to a partial or incomplete knowledge of the failure process. As a consequence, RA is always affected by the so called epistemic uncertainty which presence makes inappropriate the classical probabilistic approach. Therefore, the present work deals with such a kind of uncertainty in the Fault Tree Analysis (FTA) and proposes a new aggregation rule to combine the interval-valued information supplied by a team of experts about each Basic Event ( BE). The aggregation leads to an interval which bounds are modell…
A bottom-up procedure to calculate the Top Event probability in presence of epistemic uncertainty
2012
Industrial plants may be subjected to very dangerous events. Different methodologies are employed to evaluate the probability of their occurrence, as Process Safety Analysis (PSA) or Risk Analysis (RA). However, since for rare events reliability data are poor, the epistemic uncertainty needs to be considered. In this context, the classical probabilistic approach cannot be successfully used and then different approaches must be taken into account. Actually, this paper proposes the use of the Evidence Theory or Dempster-Shafer Theory (DST) to deal with data characterizing rare events in high risk industrial sites. In particular, a classical Fault Tree Analysis (FTA) is considered when the onl…
Uncertain outcome presentations bias decisions: experimental evidence from Finland and Italy
2016
Even in their everyday lives people are expected to make difficult decisions objectively and rationally, no matter how complex or uncertain the situation. In this research, we study how the format of presentation and the amount of presented information concerning risky events influence the decision-making process, and the propensity to take risk in decision makers. The results of an exploratory survey conducted in Finland and in Italy suggest that decision-making behavior changes according to the way the information is presented. We provide experimental evidence that different representations of expected outcomes create distinct cognitive biases and as a result affect the decisions made. Th…
Modeling risk perception in ATIS context through Fuzzy Logic
2011
Abstract This research is aimed at investigating the effect of accuracy of ATIS (Advanced Traveller Information Systems) in terms of route choices and travellers concordance to informative system. A Stated Preference Experiment has been made by using a Travel Simulator developed at the Technische Universiteit of Delft (The Netherlands). During the experiment respondents have been asked to make repeated route choices in presence of ATIS. Two kinds of information have been tested: descriptive (respondents are provided with the estimated travel times on each route), and prescriptive (respondents are provided with the estimated shortest route). For each kind of information four levels of accura…
Determining the appropriate timing of the next forest inventory: incorporating forest owner risk preferences and the uncertainty of forest data quali…
2017
Key message The timing to conduct new forest inventories should be based on the requirements of the decision maker. Importance should be placed on the objectives of the decision maker and his/her risk preferences related to those objectives. Context The appropriate use of pertinent and available information is paramount in any decision-making process. Within forestry, a new forest inventory is typically conducted prior to creating a forest management plan. The acquisition of new forest inventory data is justified by the simple statement of “good decisions require good data.” Aims By integrating potential risk preferences, we examine the specific needs to collect new forest information. Meth…
Is integration of Uncertainty Management and The Last Planner System a good idea?
2018
The Last Planner System (LPS) is a tool for project planning and control, and is an important contribution from Lean Construction. LPS focuses on scheduling, task coordination and time management. Uncertainty Management (UM) is a key element in Project Management, where uncertainty is the totality of opportunities (potential upsides) and risks (potential downsides). UM addresses all types of uncertainty (related to cost, time, quality, scope, safety, customer satisfaction, company reputation, etc.). The aim of UM is to exploit the opportunities and reduce the risks. Two construction companies involved in this research are working with both LPS and UM. One has extensive experience with LPS, …
Bayesian joint modeling of bivariate longitudinal and competing risks data: An application to study patient-ventilator asynchronies in critical care …
2017
Mechanical ventilation is a common procedure of life support in intensive care. Patient-ventilator asynchronies (PVAs) occur when the timing of the ventilator cycle is not simultaneous with the timing of the patient respiratory cycle. The association between severity markers and the events death or alive discharge has been acknowledged before, however, little is known about the addition of PVAs data to the analyses. We used an index of asynchronies (AI) to measure PVAs and the SOFA (sequential organ failure assessment) score to assess overall severity. To investigate the added value of including the AI, we propose a Bayesian joint model of bivariate longitudinal and competing risks data. Th…
Uncertainty at Work How to Regulate it through Leadership in order to improve the Quality of Work Life?
2022
This thesis manuscript focuses on factors able to regulate the uncertainty of people at work. Due to the constant evolution of the organizational world, uncertainty is increasingly becoming a factor with which to combine in different contexts about work. This factor constitutes a risk for individuals due to its aversive nature. In this perspective we have been interested, on the one hand, about theories concerning the concept of uncertainty. This allowed us to better understand and delimit the concept. On the other hand, we looked for ways to regulate uncertainty through the concept of leadership. This led us to consider this regulation as being either potentially possible through a directi…