Design, Engineering, and Experimental Analysis of a Simulated Annealing Approach to the Post-Enrolment Course Timetabling Problem

The post-enrolment course timetabling (PE-CTT) is one of the most studied timetabling problems, for which many instances and results are available. In this work we design a metaheuristic approach based on Simulated Annealing to solve the PE-CTT. We consider all the different variants of the problem that have been proposed in the literature and we perform a comprehensive experimental analysis on all the public instances available. The outcome is that our solver, properly engineered and tuned, performs very well on all cases, providing the new best known results on many instances and state-of-the-art values for the others

Feature-based tuning of simulated annealing applied to the curriculum-based course timetabling problem

We consider the university course timetabling problem, which is one of the most studied problems in educational timetabling. In particular, we focus our attention on the formulation known as the curriculum-based course timetabling problem, which has been tackled by many researchers and for which there are many available benchmarks. The contribution of this paper is twofold. First, we propose an effective and robust single-stage simulated annealing method for solving the problem. Secondly, we design and apply an extensive and statistically-principled methodology for the parameter tuning procedure. The outcome of this analysis is a methodology for modeling the relationship between search method parameters and instance features that allows us to set the parameters for unseen instances on the basis of a simple inspection of the instance itself. Using this methodology, our algorithm, despite its apparent simplicity, has been able to achieve high quality results on a set of popular benchmarks. A final contribution of the paper is a novel set of real-world instances, which could be used as a benchmark for future comparison

The mutation process on the ancestral line under selection

We consider the Moran model of population genetics with two types, mutation, and selection, and investigate the line of descent of a randomly-sampled individual from a contemporary population. We trace this ancestral line back into the distant past, far beyond the most recent common ancestor of the population (thus connecting population genetics to phylogeny) and analyse the mutation process along this line. To this end, we use the pruned lookdown ancestral selection graph, which consists of the set of potential ancestors of the sampled individual at any given time. A crucial observation is that a mutation on the ancestral line requires that the ancestral line occupy the top position in the graph just `before' the event (in forward time). Relative to the neutral case (that is, without selection), we obtain a general bias towards the beneficial type, an increase in the beneficial mutation rate, and a decrease in the deleterious mutation rate. This sheds new light on previous analytical results. We discuss our findings in the light of a well-known observation at the interface of phylogeny and population genetics, namely, the difference in the mutation rates (or, more precisely, mutation fluxes) estimated via phylogenetic methods relative to those observed in pedigree studies.Comment: 28 pages, 14 figure

Educational timetabling: Problems, benchmarks, and state-of-the-art results

We propose a survey of the research contributions on the field of Educational Timetabling with a specific focus on “standard” formulations and the corresponding benchmark instances. We identify six of such formulations and we discuss their features, pointing out their relevance and usability. Other available formulations and datasets are also reviewed and briefly discussed. Subsequently, we report the main state-of-the-art results on the selected benchmarks, in terms of solution quality (upper and lower bounds), search techniques, running times, and other side settings

Proteins in White Wines: Their Interaction With Tannins And Aroma Compounds

The presence of protein in white wines represents a major problem for the wine industry mainly due to the fact that proteins generate haze in the bottled white wines. Protein instability, which results in wine haze formation, is due to some grape PR-Proteins that thanks to their intrinsic resistance survive the vinification process, pass into the wine where cause the appearance of undesirable haze and deposits, leading to rejection by consumers. Protein hazing of white wines is considered to be a three-step process, involving protein denaturation followed by aggregation into colloidal particles able to scatter the visible light and make the wine turbid. Because of the complexity and the variability of the wine matrix, the factors and mechanisms involved in this process are still largely unknown. Commonly, winemakers prevent haze formation by removing the proteins through the use of bentonite. However, this treatment causes loss of wine and, being unspecific, also the removal of some aroma compounds. It has been calculated that the total cost deriving from bentonite treatments corresponds to a worldwide total amount of 1 billion dollars per year. Therefore, basic and applied research is still needed to solve the problem of protein haze formation in white wines. Firstly, the present thesis faces the problem of the impairment of aroma due to bentonite fining. In particular, the study arises from a previous investigation which suggested the existence of an interaction between proteins and aroma compounds. In this context, the interaction of the main wine protein VVTL1 with some fatty acid ethyl esters (FAEE), which are important fermentative aroma compounds has been investigated. Due to the difficulty to determine this interaction at the molecular level, Synchrotron Radiation Circular Dichroism (SRCD) has been used to study the secondary structure of the wine protein as affected by the interactions with FAEE having different chain lengths. Subsequently, the research continued with the investigation of the role played by tannins in the phenomena leading to protein instability of white wines. To this purpose, the effects of several polyphenols (deriving from wine and not) on the stability of VVTL1 has been investigated using SRCD. In parallel, the capability of tannins to react with the proteins over time in bottled wine has been evaluated by Dynamic Light Scattering (DLS) studies in a model wine system. In addition, the thermal stability of two purified proteins, which are representative of the major classes of proteins in white wine (i.e. a class IV Chitinase and the VVTL1), has been investigated by Differential Scanning Calorimetry (DSC) in the presence of the tannins purified from wine at different times after bottling. Finally, the last part of the research focuses on the possibility to produce good quantities of grape proteins in pure form starting from the in vitro culture of berry pulp tissues. These proteins can be used for molecular and functional characterisation. In particular, with this technique it is possible to label the proteins by cultivating the cellular tissues in the presence of N15 which allows the study of their fine structure and interactions by spectroscopic methods

An extended regularized adjusted plus-minus analysis for lineup management in basketball using play-by-play data

In this work we analyse basketball play-by-play data in order to evaluate the efficiency of different fiveman lineups employed by teams. Starting from the adjusted plus-minus framework, we present a modelbased strategy for the analysis of the result of partial match outcomes, extending the current literature in two main directions. The first extension replaces the classical response variable (scored points) with a comprehensive score that combines a set of box score statistics. This allows various aspects of the game to be separated. The second extension focuses on entire lineups rather than individual players, using a suitable extended model specification. The model fitting procedure is Bayesian and provides the necessary regularization. An advantage of this approach is the use of posterior distributions to rank players and lineups, providing an effective tool for team managers. For the empirical analysis, we use the 2018/2019 regular season of the Turkish Airlines Euroleague Championship, with play-by-play and box scores for 240 matches, which are made available by the league website. The results of the model fitting can be used for several investigations as, for instance, the comparative analysis of the effects of single players and the estimation of total and synergic effects of lineups monitoring. Moreover, the behaviour of players and lineups during the season, updating the estimation results after each gameday, can represent a rather useful tool