IRIS - UNIRSM (Univ. degli Studi della Repubblica di San Marino)
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Mechanical Characterization and Chemical Identification of Clear Binders for Road Surface Courses
No full textThe development of non-black asphalt mixtures for surface courses may play a significant role to improve functional, aesthetic and environmental issues of road pavements. Nowadays, the development of clear binders as substitutes for traditional bitumen in asphalt mixtures, which combine durability and mechanical properties, exalting the color of pavements for a better integration of road networks in urban and environmentally sensitive areas, is undoubtedly a timing challenge. However, the selection and classification of clear binders are often based only on color and standard requirements referred to traditional bitumen that do not describe consistently the binder behavior. A better understanding on clear binder properties is required to guide the aggregate selection and the mix design for surface layer, merging safety, aesthetical and environmental benefits into long lasting pavement. This paper presents a comprehensive experimental program, including empirical tests, infrared spectrum analysis, and rheological testing over a wide range of temperature and frequency, to determine the overall mechanical behavior of three clear binders. Results highlighted that the selected clear binders differ from traditional bitumen in terms of mechanical behavior. Different composition or origin can induce to completely different performance. Moreover, the combination of several testing procedures allowed suggesting specific application methods and uses for the three clear binders
Defining accurate delivery dates in make to order job-shops managed by workload control
No full textWorkload control (WLC) is a lean oriented system that reduces queues and waiting times, by imposing a cap to the workload released to the shop floor. Unfortunately, WLC performance does not systematically outperform that of push operating systems, with undersaturated utilizations levels and optimized dispatching rules. To address this issue, many scientific works made use of complex job-release mechanisms and sophisticated dispatching rules, but this makes WLC too complicated for industrial applications. So, in this study, we propose a complementary approach. At first, to reduce queuing time variability, we introduce a simple WLC system; next we integrate it with a predictive tool that, based on the system state, can accurately forecast the total time needed to manufacture and deliver a job. Due to the non-linearity among dependent and independent variables, forecasts are made using a multi-layer-perceptron; yet, to have a comparison, the effectiveness of both linear and non-linear multi regression model has been tested too. Anyhow, if due dates are endogenous (i.e. set by the manufacturer), they can be directly bound to this internal estimate. Conversely, if they are exogenous (i.e. set by the customer), this approach may not be enough to minimize the percentage of tardy jobs. So, we also propose a negotiation scheme, which can be used to extend exogenous due dates considered too tight, with respect to the internal estimate. This is the main contribution of the paper, as it makes the forecasting approach truly useful in many industrial applications. To test our approach, we simulated a 6-machines job-shop controlled with WLC and equipped with the proposed forecasting system. Obtained performances, namely WIP levels, percentage of tardy jobs and negotiated due dates, were compared with those of a set classical benchmark, and demonstrated the robustness and the quality of our approach, which ensures minimal delays
Critical buckling load of honeycomb sandwich panels reinforced by three-phase orthotropic skins enhanced by carbon nanotubes
No full textThe buckling analyses illustrated in this research aim to provide useful results for the design and application of sandwich plates with a honeycomb core and three-phase orthotropic skins, which are reinforced by both carbon nanotubes (CNTs) and straight oriented fibers. A multiscale approach is developed to this aim, which is based on the Eshelby-Mori-Tanaka scheme and the Hahn homogenization technique. The outcomes are presented in terms of critical buckling loads for different boundary conditions, lamination schemes, fiber orientation and mass fraction of CNTs, in order to prove that all these elements represent fundamental design parameters in the analysis, manufacturing and behavior of these sandwich plates. The theoretical framework is based on the Reissner-Mindlin theory for laminated plates and on the von Kármán hypothesis as far as the nonlinear terms are concerned. The kinematic model includes the Murakami's function to deal with such peculiar mechanical configurations, which is required to capture the zig-zag effect due to the different mechanical properties of the core and the external skins. The numerical approach and the theoretical methodology are validated by means of the comparison with the experimental and the theoretical results available in the literature
Una nuova propedeutica per i corsi in design
No full textIn questo testo si propone una ricerca d’indagine sull’utilità di corsi propedeutici nell’attuale panorama didattico internazionale del design. I corsi propedeutici trovano le prime applicazioni didattiche nel Bauhaus
e modificano la propria metodologia e forma durante le successive sperimentazioni didattiche fino ai tempi attuali. L’analisi storica di queste modifiche, associata ad una metodica analisi delle competenze e dei saperi che la figura del designer contemporaneo deve possedere, saranno le basi per lo sviluppo di un nuovo modello di didattica applicata al progetto.
Il modello proposto si innesta nei percorsi didattici attuali. Questa scelta strategica permetterà la valutazione dello stesso senza gravare su modifiche dei quadri accademici esistenti che si proporranno come caso pilota. Per questo motivo la propedeutica si ipotizza possa essere applicata durante corsi intensivi durante il mese di settembre e saranno dedicati ad ogni anno della laurea triennale. Il carattere dei corsi sarà di tipo esplorativo e vedrà il convergere nello stesso corso la professionalità di tre figure: il tecnico, il docente scientifico e il progettista. Gli studenti saranno quindi guidati ad esplorare le discipline scientifiche introdotte attraverso linguaggi progettuali propri e utilizzando le tecniche messe loro a disposizione
Valutare la self-efficacy all’Università. Uno studio pilota nel corso di Scienze dell’Educazione e della Formazione
No full textIn the process of renewing the assessment models in a socio-constructivist and centred learnerdirection, the self-assessment represents a possible declination of the formativeassessment in university study paths. It is, in fact, a process that enhances students’ criticalthinking, to understand both the difficulties and their level of self-efficacy in developinglifelong and lifewide skills, useful as well as in contexts formally assigned to learning, alsoin real and professional life. The pilot survey, carried out with a group of students from theDegree Course in Education and Training Sciences at the University of Macerata, confirmsthe importance of self-assessment and focuses attention on the perception of the constructof self-efficacy. The study, in fact, represents the first step of a broader and more complexassessment process, aimed at detecting students’ self-efficacy on their socio-cognitiveskills pursued by the study profile of socio-pedagogical educator
