Service network design problem with quality targets and stochastic travel time: new model and algorithm

Network design formulations in which time is explicitly taken as a stochastic parameter have been neglected in the service network design literature in favor of settings in which other stochastic parameters were taken into account (primarily demand). Nowadays, however, reliability is one of the major competitive dimensions of many firms. From a customer point of view, reliability - the on-time delivery of products - is a criterion that a firm must meet a priori, just to be considered as a possible supplier. From the point of view of carriers, reliability - the on-time occurrence of operations - is strictly related to the respect of an "ideal" or "imposed" schedule. This is particularly important, for consolidation-based transportation systems, where total system costs may also involve the costs raising from missing a proper sequencing of services for some commodities. In this work, we propose to study a service network design problem from a carrier point of view in which travel time is explicitly considered as a stochastic parameter in the decision process and in which the goal is to define a cost-efficient service network that satisfies given service quality targets consistently as close as possible in time. To the best of our knowledge, this is the first time such a problem has been investigated. The problem is modeled as a two-stage scenario-based stochastic programming model. In the first stage, planning decisions are made considering their future effects: the selection of the services and the routing of freight are determined with the objective of minimizing the fixed service-selection and variable demand-routing costs, plus the expected penalty costs following the application of the chosen plan to the observed realizations of travel times. The second stage addresses how to deal with delays for a given travel time realization and a chosen design. Network design problems are notoriously NP-Hard. A progressive hedging-based meta-heuristic algorithm able to provide good quality solutions to the problem is, also, proposed. The idea is to decompose the original scenario-based stochastic problem into single-scenario-sub-problems by relaxing first stage variables' non-anticipativity constraints. At each iteration, sub-problems are solved and non-anticipativity is gradually enforced trying to consolidate sub-problem solutions into a unique one, for the original problem. This is the first attempts to solve such a problem heuristically and, hence, to apply such a methodology to a SND problem with uncertainty in travel time. An extensive experimentation is reported to show the benefits in considering explicitly travel time stochasticity into the model rather having a deterministic time assumption, structural differences between stochastic and deterministic solutions and the performance of the proposed meta-heuristic algorithm. The scientific contribution of this thesis is four-fold: • to propose a new branch of research in the field of service network design problems by introducing uncertainty in time and the need of satisfying given service quality targets; • to provide an original two-stage stochastic linear mixed-integer programming formulation for the proposed SSND-SDT problem; • to show the attractiveness of the formulation and explore the role and importance of the various random parameters through an extensive numerical analysis; • to develop a progressive hedging-based meta-heuristic algorithm with a variable hierarchic approach able to efficiently find good quality solutions to the SSND-SDT

Impact of chars and readily available carbon on soil microbial respiration and microbial community composition in a dynamic incubation experiment

The carbonisation of biomass and organic residues is discussed as an opportunity to store stabilised carbon compounds in soil and to reduce mineralisation and the emission of CO2. In this study, pyrolysis char (600 °C, 30 min) and hydrothermal carbonisation char (HTC char; 210 °C, 23 bar, 8 h), both derived from maize silage, were investigated in a short-term incubation experiment of soil mixtures with or without readily available carbon (glucose) in order to reveal impacts on soil microbial respiration and community composition. In contrast to pyrolysis char, the addition of HTC char increased respiration and enhanced the growth of fungi. The addition of glucose to soil-char mixtures containing either pyrolysis or HTC char induced an additional increase of respiration, but was 35% and 39% lower compared to soil-glucose mixtures, respectively, providing evidence for a negative priming effect. No significant difference was observed comparing the soil mixtures containing pyrolysis char + glucose and HTC char + glucose. The addition of glucose stimulated the growth of most microbial taxa under study, especially of Actinobacteria at the expense of fungi. Adding pyrolysis or HTC char to soil induced a decline of all microbial taxa but did not modify the microbial community structure significantly. Addition of pyrolysis or HTC char in combination with glucose however, increased the abundance of Actinobacteria and reduced the relative abundance of Acidobacteria and Betaproteobacteria while fungi were further increased in case of HTC char. We conclude that both chars hold the potential to bring about specific impacts on soil microbial activities and microbial community structure, and that they may compensate the variations induced by the addition of readily available carbon

Impact of chars and readily available carbon on soil microbial respiration and microbial community composition in a dynamic incubation experiment

The carbonisation of biomass and organic residues is discussed as an opportunity to store stabilised carbon compounds in soil and to reduce mineralisation and the emission of CO2. In this study, pyrolysis char (600 °C, 30 min) and hydrothermal carbonisation char (HTC char; 210 °C, 23 bar, 8 h), both derived from maize silage, were investigated in a short-term incubation experiment of soil mixtures with or without readily available carbon (glucose) in order to reveal impacts on soil microbial respiration and community composition. In contrast to pyrolysis char, the addition of HTC char increased respiration and enhanced the growth of fungi. The addition of glucose to soil-char mixtures containing either pyrolysis or HTC char induced an additional increase of respiration, but was 35% and 39% lower compared to soil-glucose mixtures, respectively, providing evidence for a negative priming effect. No significant difference was observed comparing the soil mixtures containing pyrolysis char + glucose and HTC char + glucose. The addition of glucose stimulated the growth of most microbial taxa under study, especially of Actinobacteria at the expense of fungi. Adding pyrolysis or HTC char to soil induced a decline of all microbial taxa but did not modify the microbial community structure significantly. Addition of pyrolysis or HTC char in combination with glucose however, increased the abundance of Actinobacteria and reduced the relative abundance of Acidobacteria and Betaproteobacteria while fungi were further increased in case of HTC char. We conclude that both chars hold the potential to bring about specific impacts on soil microbial activities and microbial community structure, and that they may compensate the variations induced by the addition of readily available carbon

Sequencing and Routing in a Large Warehouse with High Degree of Product Rotation

The paper deals with a sequencing and routing problem originated by a real-world application context. The problem consists in defining the best sequence of locations to visit within a warehouse for the storage and/or retrieval of a given set of items during a specified time horizon, where the storage/retrieval location of an item is given. Picking and put away of items are simultaneously addressed, by also considering some specific requirements given by the layout design and operating policies which are typical in the kind of warehouses under study. Specifically, the considered sequencing policy prescribes that storage locations must be replenished or emptied one at a time by following a specified order of precedence. Moreover, two fleet of vehicles are used to perform retrieving and storing operations, whose routing is restricted to disjoint areas of the warehouse. We model the problem as a constrained multicommodity flow problem on a space-time network, and we propose a Mixed-Integer Linear Programming formulation, whose primary goal is to minimize the time traveled by the vehicles during the time horizon. Since large-size realistic instances are hardly solvable within the time limit commonly imposed in the considered application context, a matheuristic approach based on a time horizon decomposition is proposed. Finally, we provide an extensive experimental analysis aiming at identifying suitable parameter settings for the proposed approach, and testing the matheuristic on particularly hard realistic scenarios. The computational experiments show the efficacy and the efficiency of the proposed approach

Assigning and sequencing storage locations under a two level storage policy: optimization model and matheuristic approach

We deal with a storage location problem in a warehouse where items of different product types are released by the production area and need to be stored. Capacitated storage locations have to be assigned to each product type to store the corresponding items. Items of different product types cannot share the same storage location, i.e., each storage location can be assigned to at most one product type. In addition, a suitable sequencing of the assigned storage locations must be devised for each product type. Each sequence will provide both the order with which the storage locations will be filled up during the storing operations, and also the order of visit of the storage locations during the successive order picking phase. A motivation is that, separately per product type, an order picking based on the time of permanence of the items in the warehouse has to be pursued. Moreover, the chosen sequencing influences the availability of additional storage on the top of the assigned storage locations. In fact, for each product type, an additional extra storage can be made available on top of pairs of consecutive storage locations in the sequence, which depends on the two storage locations at the ground level. The goal is to maximize the storage capacity still available after the assignment of the storage locations. After proving the NP-Hardness of the considered problem, we model it in terms of a multicommodity flow problem with additional constraints on an auxiliary graph, and we propose a Mixed-Integer Linear Programming model for its mathematical formulation. A matheuristic approach, based on the sequential resolution of multicommodity flow subproblems, is then presented. The proposed methodology is applied to a case study related to a large warehouse with a high stock rotation index in tissue logistics, which motivated our study. Computational results on a wide test bed related to such a real application context show the efficiency and efficacy of the proposed approach

On the CVD Growth of C Nanotubes Over Fe-Loaded Montmorillonite Catalysts

The synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) of isobutane (i‐C4H10) over sodium‐exchanged K10‐montmorillonite based iron‐ catalysts is investigated. By studying the influence of iron‐addition (5–25wt%) on the catalyst performances, at 700 °C, an empirical relationship is derived relating the mass of CNTs synthesized with the exposed surface of loaded iron, as resulting from simultaneous change of number, size and dispersion of Fe‐nanoparticles available for the growth

Development of a Hardware/Software System for Proprioception Exergaming

Physiotherapy and rehabilitation are getting ever more relevance as an integral part of healthcare devising and employing new, effective methodologies and tools. However, not seldom are such tools boring and difficult to use properly for achieving the given training and therapeutic goals. Exergaming, the combination of physical exercise and video gaming, may help to overcome these issues by offering enjoyment and motivation. However, the literature lacks papers investigating how to integrate such devices into a serious game combining effectiveness and enjoyment. In this paper, we focus on the Balance Board (BB), a device used in gyms and in several health-related applications [1], and present an exergaming system for proprioception training. The system includes a BB, which was instrumented to act as a motion controller for an ad-hoc developed, simple 3D video game. The system aims to provide enjoyable training with the BB, boosting equilibrium exercising through the simulation of downhill skiing. We validated the score computation and tested the efficacy of the system in a user test with 40 participants, in ecological settings. The evaluation concerned user performance and a game experience questionnaire. The results showed statistically significant improvement in players’ ability to use the BB. Users also reported a positive gameplay experience

The INGV science theatre experiences

Since September 2008, the Istituto Nazionale di Geofisca e Vulcanologia in Rome has started to experiment science theatre as an innovative tool to promote seismic risk awareness and earth education. Up to now two projects have been implemented within the Laboratorio di Didattica e Divulgazione Scientifica. The first one, more traditional, involving pupils of the primary school was devoted to promote seismic risk and earthquake education among children aged 6-10. The Sicilian “Colapesce” tale was rewritten and readapted to commemorate the 100 years from 1908 Messina Earthquake, to be performed in a school theatre by pupils (II and IV classes Scuola Primaria Federico Di Donato, Rome). It was as well an experiment of science without frontiers for the presence of schoolmates from different countries (Asia, Africa, South America, East Europe and Italy). The second was a pilot-project developed in collaboration with Ente Parco dei Castelli Romani and concerning the possibility to establish in the future an Ecomuseum in one of the Lazio Region areas rich of natural landscapes and history. The students of two classrooms of the Mancinelli and Falconi Institute in Velletri (III Classical Lyceum and III Socio-Pedagogical Lyceum ), aged 16, chose an itinerary in the volcanic-origin area around the Nemi Lake to be developed in three items: the Roman Ships Museum; The lake itself; and the Diana Nemorensis Temple’s ruins. The final goal was interpreting the territory with the help of scenic actions. It was a sort of opened-air theatre where history, legends and their historical figures - mainly Caligula and the Goddess Diana - described the area from the different points of view: geological, historical, naturalistic and even gastronomic. Both the projects have been evaluated, but in the second case, one of the two classrooms, being a Socio-Pedagogical Lyceum, was involved in the evaluation process under the supervision of Ingv Didactic Lab. Results from both projects, and a comparison between the two will be shown

An Ecomuseum Experience In The Castelli Romani Area for Didactic Purposes

Among the different methodologies to educate people to the planet sustainability, the Ecomuseum is one of the most innovative and advanced. It offers the opportunity of using different didactic modules such as drama and museography in order to obtain the full involvement of the people to be educated. In the Ecomuseum, visitors are not just the observers but also interactors and in a wide perspective even the watchmen of the territory where they live. In Italy already exist eighty Ecomuseums, two already established in the Lazio Region. One of those, the one in the Agro-pontino area, is already operating at a large scale and in a European contest with great results. Following the same path, the Istituto Nazionale di Geofisica e Vulcanologia in Rome chose an area, the Albani Hills, to implement a pilot-project for the establishment of an Ecomuseum in one of the Lazio Region areas rich of natural landscapes and history. In collaboration with the Ente Parco dei Castelli Romani a program for Lyceum students was implemented during a year (2009-2010). The students of two classrooms of the Mancinelli and Falconi Institute in Velletri (III Classical Lyceum and III Socio-Pedagogical Lyceum ), aged 16, chose an itinerary in the volcanic-origin area around the Nemi Lake to be developed in three items: the Roman Ships Museum; The lake itself; and the Diana Nemorensis Temple’s ruins. The final goal was interpreting the territory with the help of scenic actions. It was a sort of opened-air theatre where history, legends and their historical figures - mainly Caligula and the Goddess Diana - described the area from the different points of view: geological, historical, naturalistic and even gastronomic. The project evaluation was assigned to a Socio-Pedagogical Lyceum, under the supervision of INGV Didactic Lab. Results are encouraging even if innovative way to gain students enthusiasm should be thought since only a small group of students participated actively to the project. For future experiences it is important to succeed in involving as many teachers as possible to have more hours at disposal to be dedicated also to the dramatization

Interoperabilität von Metadaten innerhalb der NFDI: Konsortienübergreifender Metadaten-Workshop am 2./3. Juli 2020

Auf einem virtuellen Metadatenworkshop diskutierten Vertreterinnen und Vertreter von 17 verschiedenen NFDI-Konsortien Konzepte zur Interoperabilität von Metadaten in Bezug auf inhaltliche Überschneidungen, Herangehensweisen zur Metadatenmodellierung, technische Aspekte und Infrastruktur bis hin zu organisatorischen Aspekten und Zusammenarbeit. Die vertretenen Konsortien möchten auch in Zukunft eng im Bereich Metadaten zusammenarbeiten und Standards schaffen, die es Forschenden in der Zukunft möglich machen, ihre Forschungsergebnisse gleichzeitig spezifisch und interoperabel zu beschreiben. Die Dynamik der Formierung der Nationalen Forschungsdateninfrastruktur (NFDI) soll für Einigung über allgemein bedeutsame Fragen der Metadatierung genutzt werden. Zudem sollen mit Unterstützung des NFDI-Direktorats Strukturen zur gemeinsamen Standardisierungsarbeit geschaffen und international vernetzt werden