scholarly journals Evaluation of scenario reduction algorithms with nested distance

2020 ◽  
Vol 17 (2) ◽  
pp. 241-275
Author(s):  
Markéta Horejšová ◽  
Sebastiano Vitali ◽  
Miloš Kopa ◽  
Vittorio Moriggia
Author(s):  
Seyed Kourosh Mahjour ◽  
Antonio Alberto Souza Santos ◽  
Manuel Gomes Correia ◽  
Denis José Schiozer

AbstractThe simulation process under uncertainty needs numerous reservoir models that can be very time-consuming. Hence, selecting representative models (RMs) that show the uncertainty space of the full ensemble is required. In this work, we compare two scenario reduction techniques: (1) Distance-based Clustering with Simple Matching Coefficient (DCSMC) applied before the simulation process using reservoir static data, and (2) metaheuristic algorithm (RMFinder technique) applied after the simulation process using reservoir dynamic data. We use these two methods as samples to investigate the effect of static and dynamic data usage on the accuracy and rate of the scenario reduction process focusing field development purposes. In this work, a synthetic benchmark case named UNISIM-II-D considering the flow unit modelling is used. The results showed both scenario reduction methods are reliable in selecting the RMs from a specific production strategy. However, the obtained RMs from a defined strategy using the DCSMC method can be applied to other strategies preserving the representativeness of the models, while the role of the strategy types to select the RMs using the metaheuristic method is substantial so that each strategy has its own set of RMs. Due to the field development workflow in which the metaheuristic algorithm is used, the number of required flow simulation models and the computational time are greater than the workflow in which the DCSMC method is applied. Hence, it can be concluded that static reservoir data usage on the scenario reduction process can be more reliable during the field development phase.


2020 ◽  
Vol 178 (3-4) ◽  
pp. 1125-1172
Author(s):  
Julio Backhoff-Veraguas ◽  
Daniel Bartl ◽  
Mathias Beiglböck ◽  
Manu Eder

Abstract A number of researchers have introduced topological structures on the set of laws of stochastic processes. A unifying goal of these authors is to strengthen the usual weak topology in order to adequately capture the temporal structure of stochastic processes. Aldous defines an extended weak topology based on the weak convergence of prediction processes. In the economic literature, Hellwig introduced the information topology to study the stability of equilibrium problems. Bion–Nadal and Talay introduce a version of the Wasserstein distance between the laws of diffusion processes. Pflug and Pichler consider the nested distance (and the weak nested topology) to obtain continuity of stochastic multistage programming problems. These distances can be seen as a symmetrization of Lassalle’s causal transport problem, but there are also further natural ways to derive a topology from causal transport. Our main result is that all of these seemingly independent approaches define the same topology in finite discrete time. Moreover we show that this ‘weak adapted topology’ is characterized as the coarsest topology that guarantees continuity of optimal stopping problems for continuous bounded reward functions.


2009 ◽  
Vol 24 (2) ◽  
pp. 878-888 ◽  
Author(s):  
J.M. Morales ◽  
S. Pineda ◽  
A.J. Conejo ◽  
M. Carrion

Circulation ◽  
2014 ◽  
Vol 129 (suppl_1) ◽  
Author(s):  
Piotr Bandosz ◽  
Maria Guzman-Castillo ◽  
Simon Capewell ◽  
Tomasz Zdrojewski ◽  
Julia Critchley ◽  
...  

Background: Poland has experienced one of the most dramatic declines in coronary heart disease (CHD) mortality rates in recent decades. This decline reflects the use of evidence based treatments and, crucially, population wide changes in diet. Our aim is to explore the potential for further gains in Poland by achieving population wide reductions in smoking, dietary salt and saturated fat intake and physical inactivity levels. Methods: A validated and updated policy model was used to forecast potential decreases in CHD deaths by 2020 as consequence of lifestyle and dietary changes in the population. Data from the most recent Polish risk factor survey was used for the baseline (2011). We modeled two different policy scenarios regarding possible future changes in risk factors: A) conservative scenario: reduction of smoking prevalence and physically inactivity rates by 5% between 2011 and 2020, and reduction of dietary consumption of energy from saturated fats by 1% and of salt by 10%. B) ideal scenario: reduction of smoking and physically inactivity prevalence by 15%, and dietary reduction of energy from saturated fats by 3% and of salt by 30%. We also conducted extensive sensitivity analysis using different counterfactual scenarios of future mortality trends. Results: Baseline scenarios. By assuming continuing declines in mortality and no future improvements in risk factors the predicted number of CHD deaths in 2020 would be approximately 13,600 (9,838-18,184) while if mortality rates remain stable, the predicted number of deaths would approximate 22,200 (17,792-26,688). Conservative scenario. Assuming continuing declines in mortality, small changes in risk factors could result in approximately 1,500 (688-2,940) fewer deaths. This corresponds to a 11% mortality reduction. Under the ideal scenario, our model predicted some 4,600 (2,048-8,701) fewer deaths (a 34% mortality reduction). Reduction in smoking prevalence by 5% (conservative scenario) or 15% (ideal scenario) could result in mortality reductions of 4.5% and 13.8% respectively. Decreases in salt intake by 10% or 30% might reduce CHD deaths by 3.0% and 8.6% respectively. Replacing 1% or 3% of dietary saturated fats by poly-unsaturates could reduce CHD deaths by 2.6% or 7.7% Lowering the prevalence of physically inactive people by 5%-15% could decrease CHD deaths by 1.2%-3.7%. Conclusion: Small and eminently feasible population reductions in lifestyle related risk factors could substantially decrease future number of CHD deaths in Poland, thus consolidating the earlier gains.


Sign in / Sign up

Export Citation Format

Share Document