Search results for "objective"

Integrating risk management tools for regional forest planning : an interactive multiobjective value at risk approach

2018

In this paper, we present an approach employing multiobjective optimization to support decision making in forest management planning under risk. The primary objectives are biodiversity and timber cash flow, evaluated from two perspectives: the expected value and the value-at-risk (VaR). In addition, the risk level for both the timber cash flow and biodiversity values are included as objectives. With our approach, we highlight the trade-off between the expected value and the VaR, as well as between the VaRs of the two objectives of interest. We employ an interactive method in which a decision maker iteratively provides preference information to find the most preferred management plan and lea…

On Dealing with Uncertainties from Kriging Models in Offline Data-Driven Evolutionary Multiobjective Optimization

2019

Many works on surrogate-assisted evolutionary multiobjective optimization have been devoted to problems where function evaluations are time-consuming (e.g., based on simulations). In many real-life optimization problems, mathematical or simulation models are not always available and, instead, we only have data from experiments, measurements or sensors. In such cases, optimization is to be performed on surrogate models built on the data available. The main challenge there is to fit an accurate surrogate model and to obtain meaningful solutions. We apply Kriging as a surrogate model and utilize corresponding uncertainty information in different ways during the optimization process. We discuss…

Multiobjective shape design in a ventilation system with a preference-driven surrogate-assisted evolutionary algorithm

2019

We formulate and solve a real-world shape design optimization problem of an air intake ventilation system in a tractor cabin by using a preference-based surrogate-assisted evolutionary multiobjective optimization algorithm. We are motivated by practical applicability and focus on two main challenges faced by practitioners in industry: 1) meaningful formulation of the optimization problem reflecting the needs of a decision maker and 2) finding a desirable solution based on a decision maker’s preferences when solving a problem with computationally expensive function evaluations. For the first challenge, we describe the procedure of modelling a component in the air intake ventilation system wi…

Handling expensive multiobjective optimization problems with evolutionary algorithms

2017

Multiobjective optimization problems (MOPs) with a large number of conflicting objectives are often encountered in industry. Moreover, these problem typically involve expensive evaluations (e.g. time consuming simulations or costly experiments), which pose an extra challenge in solving them. In this thesis, we first present a survey of different methods proposed in the literature to handle MOPs with expensive evaluations. We observed that most of the existing methods cannot be easily applied to problems with more than three objectives. Therefore, we propose a Kriging-assisted reference vector guided evolutionary algorithm (K-RVEA) for problems with at least three expensive objectives. The alg…

Approximation through interpolation in nonconvex multiobjective optimization

2011

Approximation method for computationally expensive nonconvex multiobjective optimization problems

2012

On solving computationally expensive multiobjective optimization problems with interactive methods

2014

Global, regional, and national levels and causes of maternal mortality during 1990-2013: A systematic analysis for the Global Burden of Disease Study…

2014

BACKGROUND: The fifth Millennium Development Goal (MDG 5) established the goal of a 75% reduction in the maternal mortality ratio (MMR; number of maternal deaths per 100,000 livebirths) between 1990 and 2015. We aimed to measure levels and track trends in maternal mortality, the key causes contributing to maternal death, and timing of maternal death with respect to delivery.METHODS: We used robust statistical methods including the Cause of Death Ensemble model (CODEm) to analyse a database of data for 7065 site-years and estimate the number of maternal deaths from all causes in 188 countries between 1990 and 2013. We estimated the number of pregnancy-related deaths caused by HIV on the basi…

Body Mass Index in the Early Years in Relation to Motor Coordination at the Age of 5–7 Years

2017

Physical activity (PA) and body mass index (BMI) are consistently associated with motor coordination (MC) in children. However, we know very little how BMI in early childhood associates with MC later in childhood. This study investigated associations between BMI in early childhood and BMI, PA, and MC in middle childhood. Children aged 5 to 7 years (n = 64, 32 girls) were measured for MC using Körperkoordinationstest für Kinder (KTK) and for moderate-to-vigorous PA (MVPA) using triaxial accelerometers. Prevailing body weight and height were measured, and information on weight and height in early years was based on parental report of child health care report cards. Age-adjusted BMIz scores we…

Swallowing evaluation with videofluoroscopy in the paediatric population

2017

Valutazione della funzione deglutitoria in videofluoroscopia nei pazienti pediatrici.I disturbi della deglutizione in età pediatrica possono essere dovuti a diverse cause, dalla condizione di prematurità e patologie malformative sino al reflusso gastro-esofageo o a patologie infettive od infiammatorie del primo tratto gastroenterico. Nei neonati il processo della deglutizione è involontario e basato su meccanismi riflessi. In seguito, nell’ infanzia, la fase orale diventa volontaria , mentre le fasi faringea ed esofagea rimangono involontarie. I disordini della deglutizione possono severamente compromettere le capacità respiratorie e l’apporto nutrizionale dei pazienti pediatrici. La videof…