Matheuristics: using mathematics for heuristic design

Matheuristics are heuristic algorithms based on mathematical tools such as the ones provided by mathematical programming, that are structurally general enough to be applied to different problems with little adaptations to their abstract structure. The result can be metaheuristic hybrids having components derived from the mathematical model of the problems of interest, but the mathematical techniques themselves can define general heuristic solution frameworks. In this paper, we focus our attention on mathematical programming and its contributions to developing effective heuristics. We briefly describe the mathematical tools available and then some matheuristic approaches, reporting some representative examples from the literature. We also take the opportunity to provide some ideas for possible future development

A Fast and Continuous CT scanner for the optimization of logs in a sawmill

CT Log is a CT scanner used in an industrial process at very high speed in order to optimize the production of wood boards and other wood products. The scanner can reach 160 m/min, the typical speed at which wood logs are sawn in the sawmills. After the logs pass though the scanner, the images are reconstructed and processed in order to allow the automatic optimization of the cutting pattern according to the constraints set by wood defects and the value of the different products. Building a a buffer between the scanner and the sawing line is expensive and often not possible because of constraints on the plant layout The time available for the entire processing is therefore very short, because it must be completed before the log reaches the breakdown equipment. In this paper, we present the structure of the scanner and the way we implemented the different stages of processing in order maximize the speed of the elaboration

Method and apparatus for non-destructive inspection of fruits having an axis of rotational symmetry

This invention relates to a method for non-destructive inspection of a fruit (1) having an axis of rotational symmetry (10). The method comprises the step of positioning the fruit (1) in such a way that its axis of rotational symmetry (10) has an orientation that is substantially parallel to a predetermined plane (20) and the step of radiographing the fruit (1), where the direction of emission of X-rays is substantially perpendicular to said predetermined plane (20) and an X-ray image obtained (41) lies on said predetermined plane (20). The X-ray image obtained (41) is processed to calculate, at corresponding points of the X-ray image (41), respective values of attenuation of the X-ray signal through the fruit (1). The X-ray image (41) is divided into a plurality of sections (415) which are perpendicular to the projection (410) of the axis of rotational symmetry (10) on the predetermined plane (20). Each section (415) is the projection of a corresponding slice of the fruit (1) that is substantially perpendicular to the axis of rotational symmetry (10). For each section (415), the deviation between a signal attenuation trend obtained from processing the X-ray image and a reference trend, or the deviation between a trend of a local coefficient of average attenuation obtained from processing the X-ray image and a trend with constant value, is examined in order to identify any anomalies, discontinuities or variations which are indicative of respective nonuniformities in the corresponding slice of fruit. This invention also relates to an apparatus (9) for carrying out a non-destructive inspection of a fruit (1) having an axis of rotational symmetry (10), said apparatus being configured for implementing the method according to the invention

Investigating Flow-Induced Corrosion of Magnesium in Ophthalmological Milieu

Although the impact of local fluid dynamics in the biodegradation of magnesium is well known, currently no studies in the literature address the degradation effects of ocular vitreous on bioresorbable devices made of magnesium, which could be developed as drug delivery carriers. The aim of this study was to investigate the flow-induced corrosion mechanism of magnesium in an ophthalmological environment for future applications in ophthalmic drug delivery. To achieve this, experimental and computational methods were combined. Specifically, a CFD model was employed to design experimental conditions that replicate the ocular flow-induced shear stress (FISS) on manufactured magnesium samples. Pure Mg samples were tested in a bioreactor system capable of imposing the ocular CFD calculated values of FISS on the Mg samples' surface by varying the pump flow rate. Optimal flow rates for a range of different FISS values specific to the ophthalmological fluid dynamics affecting the device were indeed determined before running the experiments. After conducting customized corrosion tests, morphological observations and profilometric maps of the eroded surfaces of Mg samples were obtained using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These maps were then post-processed for the parametric evaluation of corrosion rates. Pre-existing localized superficial defects did affect the final corrosion pattern. SEM images and CLSM data confirmed a uniform corrosion mechanism, with corrosion rates of 1.9, 2.7, and 3.4 mu m/day under different shear stress conditions (0, 0.01, and 0.032 Pa, respectively). More generally, uniform corrosion on pure Mg samples increased with higher FISS values, and at higher shear stress values (FISS = 0.032 Pa), a notable washing-out effect of the corrosion products was observed. The removal of corrosion products at higher shear stresses suggests that the dynamic ocular environment, influenced by saccadic movements, plays a significant role in the corrosion mechanism of pure magnesium. The corrosion rates determined in this study, in conjunction with clinical drug release requirements, are crucial for designing potential drug-release devices for ocular applications

Matheuristics:survey and synthesis

In integer programming and combinatorial optimisation, people use the term matheuristics to refer to methods that are heuristic in nature, but draw on concepts from the literature on exact methods. We survey the literature on this topic, with a particular emphasis on matheuristics that yield both primal and dual bounds (i.e., upper and lower bounds in the case of a minimisation problem). We also make some comments about possible future developments

Understanding the Origin and Mixing of Deep Fluids in Shallow Aquifers and Possible Implications for Crustal Deformation Studies: San Vittorino Plain, Central Apennines

Expanding knowledge about the origin and mixing of deep fluids and the water–rock–gas interactions in aquifer systems can represent an improvement in the comprehension of crustal deformation processes. An analysis of the deep and meteoric fluid contributions to a regional groundwater circulation model in an active seismic area has been carried out. We performed two hydrogeochemical screenings of 15 springs in the San Vittorino Plain (central Italy). Furthermore, we updated the San Vittorino Plain structural setting with a new geological map and cross-sections, highlighting how and where the aquifers are intersected by faults. The application of Na-Li geothermometers, coupled with trace element and gas analyses, agrees in attributing the highest temperatures (>150 °C), the greatest enrichments in Li (124.3 ppb) and Cs (>5 ppb), and traces of mantle-derived He (1–2%) to springs located in correspondence with high-angle faults (i.e., S5, S11, S13, and S15). This evidence points out the role of faults acting as vehicles for deep fluids into regional carbonate aquifers. These results highlight the criteria for identifying the most suitable sites for monitoring variations in groundwater geochemistry due to the uprising of deep fluids modulated by fault activity to be further correlated with crustal deformation and possibly with seismicit

Space market uptake in Europe

The launch of the European Union (EU) Space Policy in 2007 gave a new momentum to the implementation of the two European space flagship programmes Copernicus (Earth Observation) and Galileo (GNSS - Global Navigation Satellite System). Whereas Galileo is still in its deployment phase, Copernicus has already entered the exploitation phase. So far, roughly EUR 6 billion have been funded by the EU for the design and development of the two programmes and more than EUR 11 billion have been earmarked in the 2014-2020 programming period. Key rationales for EU intervention in the space sector include: i) the need to develop an independent European space satellite infrastructure, ii) the advantage of putting together resources and expertise from ESA and Member States, and iii) the opportunity to benefit from the development of a satellite-based services and products that would contribute to the achievement of the Europe 2020 objectives

Artificial Intelligence Application to Screen Abdominal Aortic Aneurysm Using Computed tomography Angiography

The aim of our study is to validate a totally automated deep learning (DL)-based segmentation pipeline to screen abdominal aortic aneurysms (AAA) in computed tomography angiography (CTA) scans. We retrospectively evaluated 73 thoraco-abdominal CTAs (48 AAA and 25 control CTA) by means of a DL-based segmentation pipeline built on a 2.5D convolutional neural network (CNN) architecture to segment lumen and thrombus of the aorta. The maximum aortic diameter of the abdominal tract was compared using a threshold value (30 mm). Blinded manual measurements from a radiologist were done in order to create a true comparison. The screening pipeline was tested on 48 patients with aneurysm and 25 without aneurysm. The average diameter manually measured was 51.1 ± 14.4 mm for patients with aneurysms and 21.7 ± 3.6 mm for patients without aneurysms. The pipeline correctly classified 47 AAA out of 48 and 24 control patients out of 25 with 97% accuracy, 98% sensitivity, and 96% specificity. The automated pipeline of aneurysm measurements in the abdominal tract reported a median error with regard to the maximum abdominal diameter measurement of 1.3 mm. Our approach allowed for the maximum diameter of 51.2 ± 14.3 mm in patients with aneurysm and 22.0 ± 4.0 mm in patients without an aneurysm. The DL-based screening for AAA is a feasible and accurate method, calling for further validation using a larger pool of diagnostic images towards its clinical use

A Heat Pump-Based Multi-source Renewable Energy System for the Building Air Conditioning: The IDEAS Project Experience

The current paper presents the state-of-the-art of the ongoing IDEAS research project, funded under the Horizon 2020 EU framework programme. The project involves fourteen partners from six European countries and proposes a multi-source cost-effective renewable energy system for the decarbonisation of the building envelope. The system features a radiant floor fed by a heat pump for the building thermal management. The heat pump can exploit sun, air, and/or ground as thermal sources through the use of photovoltaic/thermal solar panels, air heat exchangers, and shallow ground flat-panel heat exchangers. Thermal energy storage is achieved by means of phase change materials spread along several system components, such as: radiant floor to increase its thermal inertia, solar panels for cooling purposes, ground to enhance soil thermal capacity. Within the project framework, a small- scale building, featuring a plethora of sensors for test purposes, and two large-scale buildings are meant to be equipped with the renewable energy system proposed. The small- scale building is currently in operation, and the first results are discussed in the present work. Preliminary data suggest that while multi-source systems coupled with heat pumps are particularly effective, it is complex to obtain suitable thermal energy storages on urban scale