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Multi-objective Evolutionary Algorithms for Influence Maximization in Social Networks
No full textAs the pervasiveness of social networks increases, new NP-hard related problems become interesting for the optimization community. The objective of influence maximization is to contact the largest possible number of nodes in a network, starting from a small set of seed nodes, and assuming a model for information propagation. This problem is of utmost practical importance for applications ranging from social studies to marketing. The influence maximization problem is typically formulated assuming that the number of the seed nodes is a parameter. Differently, in this paper, we choose to formulate it in a multi-objective fashion, considering the minimization of the number of seed nodes among the goals, and we tackle it with an evolutionary approach. As a result, we are able to identify sets of seed nodes of different size that spread influence the best, providing factual data to trade-off costs with quality of the result. The methodology is tested on two real-world case studies, using two different influence propagation models, and compared against state-of-the-art heuristic algorithms. The results show that the proposed approach is almost always able to outperform the heuristics
Applications of Evolutionary Computation (Part II)
No full textThe two volumes LNCS 10199 and 10200 constitute the refereed conference proceedings of the 20th European Conference on the Applications of Evolutionary Computation, EvoApplications 2017, held in Amsterdam, The Netherlands, in April 2017, colocated with the Evo* 2017 events EuroGP, EvoCOP, and EvoMUSART
Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors
No full textWe report here the synthesis of carbon-supported ZrO2 nanoparticles from zirconium oxyphthalocyanine (ZrOPc) and acetylacetonate [Zr(acac)4]. Using thermogravimetric analysis (TGA) coupled with mass spectrometry (MS), we could investigate the thermal decomposition behavior of the chosen precursors. According to those results, we chose the heat treatment temperatures (THT) using partial oxidizing (PO) and reducing (RED) atmosphere. By X-ray diffraction we detected structure and size of the nanoparticles; the size was further confirmed by transmission electron microscopy. ZrO2 formation happens at lower temperature with Zr(acac)4 than with ZrOPc, due to the lower thermal stability and a higher oxygen amount in Zr(acac)4. Using ZrOPc at THT C900 °C, PO conditions facilitate the crystallite growth and formation of distinct tetragonal ZrO2, while with Zr(acac)4 a distinct tetragonal ZrO2 phase is observed already at THT C750 °C in both RED and PO conditions. Tuning of ZrO2 nanocrystallite size from 5 to 9 nm by varying the precursor loading is also demonstrated. The chemical state of zirconium was analyzed by X-ray photoelectron spectroscopy, which confirms ZrO2 formation from different synthesis routes
A Mechatronic Pneumatic Device to Improve Diastolic Function by Intermittent Action on Lower Limbs
No full textIndividuals with walking disability, as a result of pathological conditions or traumas, show a reduction in left ventricle end diastolic volume (EDV). In fact EDV is closely related to the blood pressure gradient between the postcaval vein and the right atrium which, during locomotion, is partially due to the calf veins squeezing caused by the rhythmic contraction of the triceps surae and the crushing of the sole of the foot's veins. In this study, a mechatronic device was applied to nineteen healthy voluntary participants' lower limbs to test cardiodynamic response to a mechanical intermittent stimulation. The device consisted of inflatable bladders embedded in two shells and acting on the skin of the calf and foot of both legs. The pressure trend on the legs was regulated by a portable programmable logic controller. During the compression protocol to the legs, which involved some sequences of activation-deactivation following a peristaltic compression having a caudal-rostral trend, EDV, assessed by the impedance cardiography technique, increased of about 10% up the pre-test value. The legs compression protocol imposed by means of our pneumatic device might be useful to avoid the negative consequences for cardiovascular performance caused by de-conditioning status linked to walking disabilities
Effects of pelletizing pressure and the addition of woody bulking agents on the physical and mechanical properties of pellets made from composted pig solid fraction
No full textThis study reports the effects of the addition of different woody bulking agents and pelletizing pressure on the final bulk density, durability and compression resistance of pellets manufactured from composted pig solid fraction. Two pressure levels (3.5 and 5.0 MPa) and three different types of compost (SFC - pig solid fraction, BC - pig solid fraction mixed with woody biochar, and WC - pig solid fraction mixed with wood chips) were investigated. The study shows that the different pressures adopted - in the range of 3.5 to 5.0 MPa - and the addition of woody bulking agents did not significantly affect the physical and mechanical properties of the pellets. However, according to the results of the study, the particle dimension of the woody bulking agents plays a key role in the mechanical properties of the pellets; the smaller the particles, the higher the pellet mechanical properties. The pelletizing process increased the bulk density of the investigated composts, and pellet durability was always high (> 80%). Nevertheless, when comparing the two bulking agents, the best results in terms of final quality were observed for pellets made from pig solid fraction mixed with woody biochar
A novel vertical greenery module system for building envelopes: The results and outcomes of a multidisciplinary research project
No full textVegetation in architecture can be considered a proper design strategy that is aimed at improving not only the performances of buildings, but also the outdoor climate. Different technological solutions have been proposed over the years to cover buildings with vegetation, i.e. green roofs, green walls and green balconies. A particular typology of green wall, which has recently been gaining high consensus among designers, is the vertical greenery modular system (VGMS). The positive impact of this type of technology on the performance of buildings is related to several factors, such as the façade orientation, the use of the building, climatic conditions, the type of plants, the substrates and wall assemblies, as well as mechanical and technological issues. A multidisciplinary approach is therefore needed, and different skills have to be joined together right from the early design phase in order to optimize and balance all the aspects that are involved. In this framework, a research project has been carried out in Turin (North West Italy), with the aim of developing a novel VGMS, constituted by a modular box covered with vegetation, made up of recycled/natural and highly performing materials from the energy/environmental point of view. After the design phase, the actual performance of the VGMS was assessed, through laboratory and long-term in field monitoring, and at the same time, the technological issues, biometric parameters, and the acoustic, thermal and mechanical aspects were investigated
Il gioco della Pallamaglio tra Torino e Venaria Reale
No full textIl saggio focalizza la presenza del gioco del Pallamaglio nei suoi aspetti di gioco pubblico (presso i giardini del Valentino, già barco di caccia sabaudo riconvertito a usi pubblici già a fine XVII secolo) e di gioco di corte (presso il parco di Venaria Reale, dove caratterizza uno dei viali principali e nel '700 viene integrato al labirinto e al suo padiglione progettato da Filippo Juvarra)
