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Innovative On-the-Fly Approach to Soft Landings in Quadruped Robotics

Panichi, Edoardo (author)

In this thesis, we introduce a novel approach aimed at enhancing the jumping and landing capabilities of quadruped robots. Our method integrates both model-based and model-free strategies and features a behavioral cloning framework designed to reduce computational delays often encountered in trajectory optimization.<br/><br/>Initially, we build...

master thesis 2024

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Feller property of regime-switching jump diffusion processes with hybrid jumps

Blom, H.A.P. (author)

The transition kernel of an ℝ ⁿ-valued diffusion or jump diffusion process {X _t} is known to satisfy the Feller property if {X _t} is the solution of an SDE whose coefficients are Lipschitz continuous. This Lipschitz route to Feller falls short if {X _t} is the solution of an SDE whose coefficients...

journal article 2024

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Curriculum-Based Deep Reinforcement Learning for Explosive Jumping in Quadruped Robots

Atanassov, Vassil (author)

Legged animals possess extraordinary agility with which they can gracefully traverse a wide range of environments, from running through grasslands to jumping across cliffs and climbing nearly vertical walls. Inspired by this, in this work, we use Deep Reinforcement Learning to give legged robots the ability to perform a diverse set of highly...

master thesis 2023

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A reliability assessment of grandstand elements: How can the structural reliability of a concrete grandstand element subjected to dynamical crowd loads be determined?

Weijs, Harrie (author)

On the 17th of October 2021, a concrete grandstand element collapsed at the Goffert stadium in the Netherlands after a crowd jumped on it for 8 seconds. An investigation by an engineering consultancy firm concluded that the design loads in the building code are too low, raising questions about the safety of grandstand elements. Currently, no...

master thesis 2023

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Pricing multi-dimensional American options using kernel ridge regression

Chen, Qianqian (author)

American option pricing has been an active research area in financial engineering over the past few decades. Since no analytic closed-form solution exists, various numerical approaches have been developed. Among all proposed methods, the least square Monte Carlo(LSMC) approach is the most successful and popular. The LSMC utilizes linear...

master thesis 2023

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Air entrainment and free-surface fluctuations in A-type hydraulic jumps with an abrupt drop

Luo, Maoyi (author), Wang, Hang (author), Zheng, Xiaohui (author), Wüthrich, D. (author), Bai, Ruidi (author), Liu, Shanjun (author)

In high dam construction projects in China, stilling basin design with an abrupt bottom drop is sometimes introduced to reduce the bottom velocity and pressure loads by generating A-type hydraulic jumps. Although the stilling basin design is not new, A-type hydraulic jumps have not been studied taking into account the air entrainment and...

journal article 2023

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Sticky PDMP samplers for sparse and local inference problems

Bierkens, G.N.J.C. (author), Grazzi, S. (author), van der Meulen, F.H. (author), Schauer, M.R. (author)

We construct a new class of efficient Monte Carlo methods based on continuous-time piecewise deterministic Markov processes (PDMPs) suitable for inference in high dimensional sparse models, i.e. models for which there is prior knowledge that many coordinates are likely to be exactly 0. This is achieved with the fairly simple idea of endowing...

journal article 2023

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Models and methods for hybrid system identification: a systematic survey

Moradvandi, A. (author), Lindeboom, R.E.F. (author), Abraham, E. (author), De Schutter, B.H.K. (author)

Dynamical systems and processes that either exhibit non-smooth behaviours (e.g. through logic control or natural phenomena) or work in different modes of operation are usually represented using hybrid systems models, i.e. mathematical models that combine continuous dynamics with discrete-event dynamics. Identification of a hybrid system...

conference paper 2023

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Effect of probe size on phase-detection probe measurements of air-water flow properties in hydraulic jumps

Shi, Rui (author), Wüthrich, D. (author), Chanson, Hubert (author)

This experimental study investigated the air-water flow properties and bubble characteristics in hydraulic jumps with Froude numbers Fr₁ = 2.4 and 6.3, using four dual-tip phase detection probes with sensor sizes from 0.25 mm to 0.64 mm. The hydraulic jumps were characterized by a fully breaking roller with substantial air...

journal article 2023

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Stability of backward stochastic differential equations: the general Lipschitz case

Papapantoleon, A. (author), Possamaï, Dylan (author), Saplaouras, Alexandros (author)

In this paper, we obtain stability results for backward stochastic differential equations with jumps (BSDEs) in a very general framework. More specifically, we consider a convergent sequence of standard data, each associated to their own filtration, and we prove that the associated sequence of (unique) solutions is also convergent. The...

journal article 2023

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Analyzing point spread functions for multiple emitter fitting by posterior density estimation

van Dijk, Raymond (author)

The microscope is an essential tool for biologists. Since the late 16th century, it has given researchers a better understanding of cell processes and greatly advanced healthcare. In this century, Single molecule localization microscopy (SMLM) has revolutionized optical microscopy by breaking the optical diffraction limit. Sparsely activating...

master thesis 2022

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Using CFD to design riprap bed protections downstream of underflow weirs: Weir design of the future

van Koelen, Luc (author)

Weirs are constructed inside rivers to manage the water level. On the one hand they need to be designed sufficiently strong to prevent failure or destruction, while on the other hand they need to be economically feasible. If a structure is designed too strong, unnecessary costs are made and the structure becomes too expensive.<br/><br/>One of...

master thesis 2022

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On the Efficiency of Staggered C-Grid Discretization for the Inviscid Shallow Water Equations from the Perspective of Nonstandard Calculus

Zijlema, Marcel (author)

This paper provides a rationale for the commonly observed numerical efficiency of staggered C-grid discretizations for solving the inviscid shallow water equations. In particular, using the key concepts of nonstandard calculus, we aim to show that the grid staggering of the primitive variables (surface elevation and normal velocity components)...

journal article 2022

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Two-phase air-water flows in hydraulic jumps at low Froude number: Similarity, scale effects and the need for field observations

Estrella, Jorge (author), Wüthrich, D. (author), Chanson, Hubert (author)

A hydraulic jump is a region of rapidly-varied flow that is extremely turbulent. While the one-dimensional continuity and momentum principles have been successfully applied to express the relationships between upstream and downstream conditions, the three-dimensional equations cannot be resolved without some complicated turbulence closure,...

journal article 2022

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Hydraulic jumps with low inflow Froude numbers: air–water surface patterns and transverse distributions of two-phase flow properties

Wüthrich, D. (author), Shi, Rui (author), Chanson, Hubert (author)

Abstract: Hydraulic jumps are commonly employed as energy dissipators to guarantee long-term operation of hydraulic structures. A comprehensive and in-depth understanding of their main features is therefore fundamental. In this context, the current study focused on hydraulic jumps with low Froude numbers, i.e. Fr₁ = 2.1 and 2.4, at...

journal article 2022

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Conditioning continuous-time Markov processes by guiding

Corstanje, M.A. (author), van der Meulen, F.H. (author), Schauer, M.R. (author)

A continuous-time Markov process X can be conditioned to be in a given state at a fixed time T&gt;0 using Doob's h-transform. This transform requires the typically intractable transition density of X. The effect of the h-transform can be described as introducing a guiding force on the process. Replacing this force with an approximation...

journal article 2022

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Flux large deviations of weakly interacting jump processes via well-posedness of an associated Hamilton-Jacobi equation

Kraaij, R.C. (author)

We establish uniqueness for a class of first-order Hamilton-Jacobi equations with Hamiltonians that arise from the large deviations of the empirical measure and empirical flux pair of weakly interacting Markov jump processes. As a corollary, we obtain such a large deviation principle in the context of weakly interacting processes with time...

journal article 2021

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Limit theorems for cloning algorithms

Angeli, Letizia (author), Grosskinsky, S.W. (author), Johansen, Adam M. (author)

Large deviations for additive path functionals of stochastic processes have attracted significant research interest, in particular in the context of stochastic particle systems and statistical physics. Efficient numerical ‘cloning’ algorithms have been developed to estimate the scaled cumulant generating function, based on importance sampling...

journal article 2021

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Martingale decompositions and weak differential subordination in UMD Banach spaces

Yaroslavtsev, I.S. (author)

In this paper, we consider Meyer–Yoeurp decompositions for UMD Banach space-valued martingales. Namely, we prove that X is a UMD Banach space if and only if for any fixed p ∈ (1, ∞), any X-valued L^p-martingale M has a unique decomposition M = M^d + M^c such that M^d is a purely discontinuous martingale...

journal article 2019

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Toward Optimal Metal–Organic Frameworks for Adsorption Chillers: Insights from the Scale-Up of MIL-101(Cr) and NH₂-MIL-125

Graf, Stefan (author), Redder, Florian (author), Bau, Uwe (author), de Lange, M.F. (author), Kapteijn, F. (author), Bardow, André (author)

The metal–organic frameworks (MOFs) MIL-101(Cr) and NH₂-MIL-125 offer high adsorption capacities and have therefore been suggested for sustainable energy conversion in adsorption chillers. Herein, these MOFs are benchmarked to commercial Siogel. The evaluation method combines small-scale experiments with dynamic modeling of full...

journal article 2019