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van Zon, Manon (author)Intensity modulated proton therapy is an advanced radiotherapy technique that is used to treat cancer patients. In order to successfully treat a patient, sufficient dose to the tumor is required. However, during the fractionated treatment, multiple errors can cause a difference between the planned and actual dose delivery. To ensure adequate...master thesis 2023
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Fransen, M.P. (author), Langelaar, Matthijs (author), Schott, D.L. (author)In design optimization of bulk handling equipment (BHE) we generally focus on the mean performance of the equipment. However, granular materials behave stochastic due to irregularities in particle shape and size which leads to stochastic performance of the equipment. To include the stochastic performance we propose robust metamodel-based...journal article 2023
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Nazari-Shirkouhi, Salman (author), Miralizadeh Jalalat, Sepideh (author), Sangari, Mohamad Sadegh (author), Sepehri, A. (author), Rezaei Vandchali, Hadi (author)Attaining sustainability objectives has received wide attention in the supplier selection and order allocation (SSOA) literature. This paper aims to investigate an SSOA problem under multiple items, multiple suppliers, multiple price levels, and multiple period using a robust-fuzzy multi-objective programming in which: (a) transportation cost,...journal article 2023
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Robust design of CAV-Dedicated lanes considering CAV demand uncertainty and lane reallocation policySeilabi, Sania E. (author), Pourgholamali, Mohammadhosein (author), Correia, Gonçalo (author), Labi, Samuel (author)Reduced headways of connected and automated vehicles (CAV) provide opportunities to address traffic congestion and environmental adversities. This benefit can be utilized by deploying CAV-dedicated lanes (CAVDL). This paper presents a bi-level optimization model that captures CAV market size uncertainty. The upper level determines the links ...journal article 2023
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Pourmohammadzia, N. (author), Schulte, F. (author), González-Ramírez, Rosa G. (author), Voß, Stefan (author), Negenborn, R.R. (author)Modern ports face significant challenges as strategic nodes of global supply chains, being responsible for the coordination of inbound and outbound flows at deep-sea and in hinterland transport corridors. Digitization and the adoption of disruptive technologies can help ports to tide over operational challenges. Automated Ground Vehicles ...journal article 2023
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Cohen, Izack (author), Postek, K.S. (author), Shtern, Shimrit (author)Real-life parallel machine scheduling problems can be characterized by: (i) limited information about the exact task duration at the scheduling time, and (ii) an opportunity to reschedule the remaining tasks each time a task processing is completed and a machine becomes idle. Robust optimization is the natural methodology to cope with the first...journal article 2022
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Soghrati Ghasbeh, Sogand (author), Pourmohammadzia, N. (author), Rabbani, Masoud (author)Purpose: This paper aims to address a location-distribution-routing problem for distributing relief commodities during a disaster under uncertainty by creating a multi-stage model that can consider information updates during the disaster. This model aims to create a relief network that chooses distribution centers with the highest value while...journal article 2022
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Straathof, Robin (author)Brachytherapy (BT) is an essential component in the treatment of cervical cancer as it allows for locally delivering a high dose to the tumour with minimal trauma to surrounding tissues and organs at risk (OARs). However, in advanced cervical cancer patients commercially available BT applicators are particularly ill-adapted and therefore result...master thesis 2021
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Marquez Calvo, O.O. (author)The exercise of solving engineering problems that require optimisation procedures can be seriously affected by uncertain variables, resulting in potential underperforming solutions. Although this is a well-known problem, important knowledge gaps are still to be addressed. For example, concepts of robustness largely differ from study to study,...doctoral thesis 2020
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Ramaswamy, K. R. (author), Fonseca, R. M. (author), Leeuwenburgh, O. (author), Siraj, M.M. (author), Van den Hof, P.M.J. (author)We are concerned with the efficiency of stochastic gradient estimation methods for large-scale nonlinear optimization in the presence of uncertainty. These methods aim to estimate an approximate gradient from a limited number of random input vector samples and corresponding objective function values. Ensemble methods usually employ Gaussian...journal article 2020
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Caunhye, Aakil M. (author), Aydin, N.Y. (author), Duzgun, H. Sebnem (author)Route restoration is considered to be a task of foremost priority in disaster relief. In this paper, we propose a robust optimization approach for post-disaster route restoration under uncertain restoration times. We present a novel decision rule based on restoration time ordering that yields optimal restoration sequencing and propose...journal article 2020
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Marquez Calvo, O.O. (author), Solomatine, D.P. (author)This paper considers the problem of robust optimization, and presents the technique called Robust Optimization and Probabilistic Analysis of Robustness (ROPAR). It has been developed for finding robust optimum solutions of a particular class in model-based multi-objective optimization (MOO) problems (i.e. when the objective function is not known...journal article 2019
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Jesus de Moraes, R. (author), Fonseca, Rahul-Mark (author), Helici, Mircea A. (author), Heemink, A.W. (author), Jansen, J.D. (author)We present an efficient workflow that combines multiscale (MS) forward simulation and stochastic gradient computation - MS-StoSAG - for the optimization of well controls applied to waterflooding under geological uncertainty. A two-stage iterative Multiscale Finite Volume (i-MSFV), a mass conservative reservoir simulation strategy, is employed as...journal article 2019
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Shaéezadeh-Abadeh, Soroosh (author), Kuhn, Daniel (author), Mohajerin Esfahani, P. (author)The goal of regression and classification methods in supervised learning is to minimize the empirical risk, that is, the expectation of some loss function quantifying the prediction error under the empirical distribution. When facing scarce training data, overfitting is typically mitigated by adding regularization terms to the objective that...journal article 2019
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Morales-Espana, G. (author), Lorca, Álvaro (author), de Weerdt, M.M. (author)The increasing penetration of uncertain generation such as wind and solar in power systems imposes new challenges to the unit commitment (UC) problem, one of the most critical tasks in power systems operations. The two most common approaches to address these challenges — stochastic and robust optimization — have drawbacks that restrict their...journal article 2018
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Rehman, S.U. (author), Langelaar, Matthijs (author)A novel adaptive sampling scheme for efficient global robust optimization of constrained problems is proposed. The method addresses expensive to simulate black-box constrained problems affected by uncertainties for which only the bounds are known, while the probability distribution is not available. An iterative strategy for global robust...journal article 2017
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Rehman, S.U. (author), Langelaar, Matthijs (author)Fabrication variations can have a detrimental effect on the performance of optical filters based on ring resonators. However, by using robust optimization these effects can be minimized and device yield can be significantly improved. This paper presents an efficient robust optimization technique for designing manufacturable optical filters based...journal article 2016
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Fonseca, R.M. (author), Chen, B (author), Jansen, J.D. (author), Reynolds, Albert C. (author)We consider a technique to estimate an approximate gradient using an ensemble of randomly chosen control vectors, known as Ensemble Optimization (EnOpt) in the oil and gas reservoir simulation community. In particular, we address how to obtain accurate approximate gradients when the underlying numerical mod- els contain uncertain parameters...journal article 2016
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Perko, Z. (author), van der Voort, S.R. (author), Van De Water, Steven (author), Hartman, C.M.H. (author), Hoogeman, M.S. (author), Lathouwers, D. (author)The highly conformal planned dose distribution achievable in intensity modulated proton therapy (IMPT) can severely be compromised by uncertainties in patient setup and proton range. While several robust optimization approaches have been presented to address this issue, appropriate methods to accurately estimate the robustness of treatment...journal article 2016
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Fonseca, R.M. (author)In this dissertation we have investigated theoretical and numerical aspects of the Ensemble Optimization (EnOpt) technique for model based production optimization. We have proposed a modified gradient formulation for robust optimization which we show to be theoretically more robust than the earlier existing formulation. Through a series of...doctoral thesis 2015