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Author(s):  
Frederik Schulze Spüntrup ◽  
Giancarlo Dalle Ave ◽  
Lars Imsland ◽  
Iiro Harjunkoski

AbstractLarge fleets of engineering assets that are subject to ongoing degradation are posing the challenge of how and when to perform maintenance. For a given case study, this paper proposes a formulation for combined scheduling and planning of maintenance actions. A hierarchical approach and a two-stage approach (with either uniform or non-uniform time grid) are considered and compared to each other. The resulting discrete-time linear programming model follows the Resource Task Network framework. Asset deterioration is considered linearly and tackled with an enumerator-based formulation. Advantages of the model are its computational efficiency, scalability, extendability and adaptability. The results indicate that combined maintenance planning and scheduling can be solved in appropriate time and with appropriate accuracy. The decision-support that is delivered helps the choice of the specific maintenance action to perform and proposes when to conduct it. The paper makes a case for the benefits of optimally combining long-term planning and short-term scheduling in industrial-sized problems into one system.


2021 ◽  
Author(s):  
Johannes Helm ◽  
Clemens Gruenwald-Gruber ◽  
Andreas Thader ◽  
Jonathan Urteil ◽  
Johannes Fuehrer ◽  
...  

The importance of protein glycosylation in the biomedical field demands for methods capable of resolving and identifying isomeric structures of N-glycans. However, the unambiguous identification of isomeric structures from complex mixtures is currently not reasonably realized even by the most sophisticated approaches. Here we present a novel approach which uses stable isotope labelled reference N-glycans to establish a retention time grid (glyco-TiGr) on porous graphitized carbon. This furthermore enables retention as the primary criterion for the structural assignment of isomeric N-glycans. Moreover, we biosynthesized forty natural isomers of the fundamental N-glycan type consisting of five hexoses, four N-acetylhexosamines and one fucose residue. Nearly all of these isomers occupied unique positions on the retention time grid. Reference glycan assisted retention time determination with deci-minute accuracy narrowed the assignment space to very few, often only one possible glycan isomer. Application of the glyco-TiGr approach revealed yet undescribed isomers of Lewis x determinants in multimeric human IgA and hybrid type N-glycans in human brain with galactose and even fucose linked to the bisecting N-acetylglucosamine. Thus, the brain N-glycome displayed a degree of sophistication commensurate with this organ's role.


Author(s):  
Wayne Carr ◽  
Gregory A. Wolven ◽  
Gregory J. Shirek
Keyword(s):  

Author(s):  
Francesco Bianchi ◽  
Lorenzo Mercuri ◽  
Edit Rroji

AbstractIn this paper we consider a portfolio selection problem defined for irregularly spaced observations. We use the Independent Component Analysis for the identification of the dependence structure and continuous-time GARCH models for the marginals. We discuss both estimation and simulation of market prices in a context where the time grid of price quotations differs across assets. We present an empirical analysis of the proposed approach using two high-frequency datasets that provides better out-of-sample results than competing portfolio strategies except for the case of severe market conditions with frequent rebalancements.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mathieu Roget ◽  
Basile Herzog ◽  
Giuseppe Di Molfetta

AbstractWe propose a new quantum numerical scheme to control the dynamics of a quantum walker in a two dimensional space–time grid. More specifically, we show how, introducing a quantum memory for each of the spatial grid, this result can be achieved simply by acting on the initial state of the whole system, and therefore can be exactly controlled once for all. As example we prove analytically how to encode in the initial state any arbitrary walker’s mean trajectory and variance. This brings significantly closer the possibility of implementing dynamically interesting physics models on medium term quantum devices, and introduces a new direction in simulating aspects of quantum field theories (QFTs), notably on curved manifold.


Author(s):  
Tobias Meyer ◽  
Jan Kraft ◽  
Bernhard Schweizer

Abstract Efficiency and accuracy of a co-simulation may considerable be increased by using a variable communication time grid. Therefore, an error estimator for controlling the macro-step size is required. Here, error estimators are derived and investigated for explicit and implicit co-simulation approaches. The manuscript focuses on mechanical co-simulation models. The basic results may, however, also be applied to arbitrary, non-mechanical co-simulation models.


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