VERTO: a visual notation for declarative process models

Declarative approaches to business process modeling allow to represent loosely-structured (declarative) processes in flexible scenarios as a set of constraints on the allowed flow of activities. However, current graphical notations for declarative processes are difficult to interpret. As a consequence, this has affected widespread usage of such notations, by increasing the dependency on experts to understand their semantics. In this paper, we tackle this issue by introducing a novel visual declarative notation targeted to a more understandable modeling of declarative processes

Effetti di scala sulla resistenza a trazione dei materiali

The dissertation analyses the scale effects on the tensile strength of materials. By the term scale effects it is meant the variation in a mechanical property as a function of structural size. In particular, it has been observed by numerous investigators that the nominal tensile strength of many materials decreases with increasing size of the specimen tested. This phenomenon is more evident in disordered materials, that is, materials that are macroscopically heterogeneous and damaged. On the basis of Weibull's statistical theory and the principles of Linear Elastic Fracture Mechanics, a self-similarity distribution for defect size is presented (Chapter 4). With this distribution the length of the most critical defect is taken to be proportional to the linear size of the specimen. It is shown that the assumption of self-similarity represents the instance of maximum disorder that can be encountered in real materials, and it supplies, in a strength-size bilogarithmic plane, a linear scaling law with an inclination of -1/2, corresponding to the power of the stress singularity envisaged by LEFM. This formulation contains the fractal concept of self-similarity, even though it is limited to maximum defect dimension. In order to consider the real nature of the micro-structure of the materials, a more complex fractal model is presented (Chapter 5) in which the property of self-similarity is extended to the entire population of defects. This topological law, based on fractal theory and on the so-called renormalisation procedure, states that in order to obtain a nominal constant strength for the material it is necessary to refer to surface areas with non integer physical dimensions. For disordered materials, such as for instance concrete and rocks, renormalised tensile strength is given by a force acting on a surface having a fractal dimension lower than 2. The dimensional decrease, always comprised in the [0, 1/2] range, represents self-similar vacancies in the undamaged section associated with the presence of pores, voids, defects, cracks, aggregate and inclusions, and it approaches the 1/2 limit only for extremely brittle and disordered materials, as is assumed, incidentally, in statistical approaches. As a rule, the scale variation taken into consideration in experimental investigations does not exceed one order of magnitude. In such circumstances, it is only possible to determine a single tangential inclination in the bilogarithmic diagram. Only by taking into account scale variations higher than one order of magnitude it proves possible to detect the transition from disordered to ordered conditions, and a continuous transition from -1/2 to zero inclination may be seen to appear. In physical reality, the peak load resistant section can be viewed as multifractal, of dimension 1.5 on small scales and dimension 2 at large scales. This clearly shows a transition from the extreme disorder that is associated with small scales, where a self-similar distribution of Griffith cracks predominates, to the extreme order of large scales, where the disorder of the microstructure is no longer visible, on account of the limited dimensions of the defects and heterogeneities. The assumption of multifractality for the microstructure of the damaged material (Chapter 7) is the basis of the so-called Multifractal Scaling Law (MFSL). Such law consists of an approximation method which imposes the concavity of the bilogarithmic curve facing upward, which contradicts Bazant's size effect law (SEL). To verify this scaling law and to determine experimentally the variation in nominal tensile strength and fracture energy, a totally innovative testing set-up has been created, involving the use of three servo-controlled jacks (Chapter 5). The interaction of the three jacks, arranged in L formation, makes it possible to centre instant by instant the resultant of the load with the respect to the undamaged section even in the presence of cracks which make the latter asymmetrical. The main goal of this instrumentation is to determine the parameters of the concrete subjected to uniform tension, eliminating any secondary bending effect which may affect the results and lead to erroneous explanations of the scale effect

The omics era: what can nuclear magnetic resonance tell us on metabolomics?

A brief overview of the potentiality and use of the metabolic fingerprint of a system or biological process is here proposed. The information on the type, quantity and variation of the pool of metabolites and its relationship with a given biological process is commonly referred to as metabolomics. One powerful analytical approach to the detection and quantitation of metabolites is by Nuclear Magnetic Resonance Spectroscopy (NMR). Additionally, the recently introduced High Resolution Magic Angle Spinning (HR-MAS) NMR approach improved dramatically the potentiality of the method allowing direct sampling of ex vivo specimens, such as tissues and cells, without any pre-treatment or extraction steps. The NMR data can be processed towards the target or non-target analysis of the metabolites. The former passes through the identification of all the metabolites, the latter adopts a multivariate statistical approach such as Principal Components Analysis. In this article, the main methodological points of NMR analysis with multivariate statistics are briefly outlined and discussed. A final case-study on the discrimination of healthy and neoplastic tissues via HR-MAS NMR metabolomics is reported as a paradigmatic application

Exploring the Role of Interdisciplinarity in Physics: Success, Talent and Luck

Although interdisciplinarity is often touted as a necessity for modern research, the evidence on the relative impact of sectorial versus to interdisciplinary science is qualitative at best. In this paper we leverage the bibliographic data set of the American Physical Society to quantify the role of interdisciplinarity in physics, and that of talent and luck in achieving success in scientific careers. We analyze a period of 30 years (1980-2009) tagging papers and their authors by means of the Physics and Astronomy Classification Scheme (PACS), to show that some degree of interdisciplinarity is quite helpful to reach success, measured as a proxy of either the number of articles or the citations score. We also propose an agent-based model of the publication-reputation-citation dynamics reproduces the trends observed in the APS data set. On the one hand, the results highlight the crucial role of randomness and serendipity in real scientific research; on the other, they shed light on a counter-intuitive effect indicating that the most talented authors are not necessarily the most successful ones.Comment: 21 pages, 19 figure

Biochar addition for 3DCP: a preliminary study

This contribution presents the first results of an ongoing research aimed at highlighting the possible reduction in the environmental impact of concrete through the synergy between two interconnected strategies: the exploitation of by-products, in this case biochar, for the realization of 3D printable cementitious conglomerates. Thanks to the use of biochar, the mixes presented are characterized by an excellent dimensional stability in the fresh state, evaluated through the extrusion test. Regarding the hardened state properties, the contribution highlights the effects of biochar-to-cement ratio, water-to-cement ratio (in combination with biochar content) and sand-to-cement ratio on the flexural and compressive strength of the mixes. The evaluation of CO2 emissions shows that a proper mix design could result in a significant reduction in CO2 emissions (up to 43%) while maintaining good mechanical performance (compressive strength of at least 60 MPa)

An experimental set-up for cyclic loading of concrete

Abstract Innovative cementitious composite materials are drawing considerable interest due to their substantially improved mechanical properties as compared to ordinary cement-based materials. Their enhanced ductility is promising and particularly suited to structural applications under severe dynamic loading conditions. Cyclic response is essential to understand the effects of loading and unloading on the material, as well as to understanding how it behaves in the transition from tension to compression. It is also fundamental to identify its properties in terms of energy dissipation and strain-rate sensitivity. This paper presents the first part of an ongoing research project which aims to develop the constitutive relationship in innovative cementitious composites and its numerical implementation. Results from this research will facilitate the investigation of the ductility and durability of existing buildings. In this paper, an experimental set-up for uniaxial cyclic loading is described. It was developed to study reversed cyclic compression/tension loadings of innovative cementitious composites. To set the cyclic loading process, cylindrical specimens of concrete were tested. All the tests were performed on a Zwick testing machine with 50 kN load cell. The machine was customised with accessories specifically designed to meet test requirements, avoiding instability and bending moments during the alternating phases of uniaxial compression and tension. Strain gauges were used to measure lateral deformations. The customized machine has shown good performance so far. In order to test specimens with a higher number of cycles and a higher loading rate, improvements to the machine are currently under development. These tests will allow greater insight into the ductility of innovative cementitious composite materials

Considerations over the Italian road bridge infrastructure safety after the Polcevera viaduct collapse: past errors and future perspectives

In the last four years, Italy experienced the collapse of five road bridge: Petrulla viaduct (2014), Annone (2016) and Ancona (2017) overpasses, Fossano viaduct (2017) and Polcevera (2018) bridge. Although for deeply different reasons, the collapses occurred can all been gathered into the same common cause: the (lack of) knowledge of the effective structural condition, a serious problem that affects existing constructions. As it will be shown in the paper, different problems such as missing of the as-built designs, an appropriate construction and movement precautions, a heavy vehicle checking, and a material decay monitoring can nevertheless be addressed as an inadequate knowledge of what is happening to/in the structure. In the first section, the paper will report a short description of the failures for the five bridges, while in the second part a main set of problems involved in bridge safety and maintenance will be discussed. Finally, in the third part, a review on innovative and peculiar investigation and monitoring techniques will be illustrated. The collected results can shed new light on future perspectives for the Civil Engineering sector, sector that has to be ready for facing the challenges of preservation, restoration and/or replacement of the existing infrastructural constructions, worldwide

feasibility and effectiveness of exoskeleton structures for seismic protection

Abstract In this study, a self-supporting structure, namely an exoskeleton, is considered as set outside a main structure and suitably connected to it. From the structural point of view, the exoskeleton is conceived as a "sacrificial" appendage, called to absorb seismic loads in order to increase the performance of the main structure. From the architectural and technological point of view, additional functions may be associated through an integrated design approach, combining seismic with urban and energy retrofitting. Particular and attractive applications can therefore be envisaged for existing buildings. A reduced-order dynamic model is introduced, in which two coupled linear viscoelastic oscillators represent the main structure and the exoskeleton structure, respectively, while either a rigid link or a dissipative viscoelastic connection is considered for the coupling. The equations of motion are set in non-dimensional form and a parametric study is carried out in the frequency domain to confirm that exoskeleton structures can be feasible and effective in reducing earthquake-induced dynamic responses

Development of a multifunctional panel for aerospace use through SLM additive manufacturing

Lattice materials can overcome the need of light and stiff structures in the aerospace industry. The wing leading edge is one of the most critical parts for both on-board subsystem and structure features: it must withstand to the aerodynamic loads and bird-strike, integrating also the anti-ice system functions. Nowadays, this part is made by different components bonded together such as external skin, internal passageways, and feeding tubes. In the present work, a single-piece multifunctional panel made by additive manufacturing will be developed. Optimal design and manufacturing are discussed according to technological constraints, aeronautical performances and sustainability