Innovative experiences in teaching conservation. Involving communities’ interests on preservationtopics by fast investigations and social media dissemination

Since 2019, the authors carried out a didactical experience trough the Preservation Studio workshop in the historical center of Vimercate, a town in the north east area of Milan, implementing a convention agreement between the Municipality and the Atheneum. The convention was arranged in order to set the relationship between the three academic courses of the Politecnico di Milano and the administration of Vimercate, supporting the teaching staff by providing ac- cessibility to various services and some public properties located in the city-cen- ter. Thanks to this kind of agreement, the courses could be supported in their activities by document centers, public associations and the members of the local community, while the teaching staff offered a constant sharing of the main activ- ities by social media and periodical disseminations through public lectures. After maturing several years of didactical workshops on the main buildings of the his- torical center of Vimercate, this paper shows the results collected with the stu- dios: the active class strategies, the on-site survey campaigns, the evolution of the results observed by year after year inspections, ND testing activities and local community involvement. The impact coming from the researches developed by the preservation classes and specific in depth studies realized by graduation thesis showed an increasing participation of the community to the topics connected to the city center: from conservation policies to future uses, historical buildings reached the attention of the people through the development of a new sensibility and perception of new values associated to the local architectural heritage

Hamiltonian solutions of the 3-body problem in (2+1)-gravity

We present a full study of the 3-body problem in gravity in flat (2+1)-dimensional space-time, and in the nonrelativistic limit of small velocities. We provide an explicit form of the ADM Hamiltonian in a regular coordinate system and we set up all the ingredients for canonical quantization. We emphasize the role of a U(2) symmetry under which the Hamiltonian is invariant and which should generalize to a U(N-1) symmetry for N bodies. This symmetry seems to stem from a braid group structure in the operations of looping of particles around each other, and guarantees the single-valuedness of the Hamiltonian. Its role for the construction of single-valued energy eigenfunctions is also discussed.Comment: 25 pages, no figure. v2: some calculation details removed to make the paper more concise (see v1 for the longer version), minor correction in a formula in the section on quantization, references added; results and conclusions unchange

Particles on a Circle in Canonical Lineal Gravity

A description of the canonical formulation of lineal gravity minimally coupled to N point particles in a circular topology is given. The Hamiltonian is found to be equal to the time-rate of change of the extrinsic curvature multiplied by the proper circumference of the circle. Exact solutions for pure gravity and for gravity coupled to a single particle are obtained. The presence of a single particle significantly modifies the spacetime evolution by either slowing down or reversing the cosmological expansion of the circle, depending upon the choice of parameters.Comment: 51 pages, 24 eps figures, late

Development of a One-Dimensional Model for the Prediction of Leakage Flows in Regenerative Pumps

Regenerative pumps are characterized by a low specific speed that place them between rotary positive displacement pumps and purely radial centrifugal pumps. They are interesting for many industrial applications since, for a given flow rate and a specified head, they allow for a reduced size and can operate at a lower rotational speed with respect to purely radial pumps. The complexity of the flow within regenerative machines makes the theoretical performance estimation a challenging task. The prediction of the leakage flow rate between the rotating and the static disks is the one that more than others has an impact on the prediction of global performance. All the classical approaches to the disk clearance problem assume that there is no relevant circumferential pressure gradient. In the present case, the flow develops along the tangential direction and the pressure gradient is intrinsically non-zero. The aim of the present work is to develop a reliable approach for the prediction of leakage flows in regenerative pumps. The method assumes that the flow inside of the disk clearance can be decomposed into several stream-tubes. Energy balance is performed for each tube, thus generating a system that can be solved numerically. The new methodology has been tuned using data obtained from the numerical simulation of virtual prototypes of regenerative pumps where the disk clearance is part of the control volume. After that, the methodology has been integrated into an existing one-dimensional code called DART (developed at the University of Florence in cooperation with Pierburg Pump Technology Italy S.p.A.) and the new algorithm is verified using available experimental and numerical data. It is here demonstrated that an appropriate calibration of the leakage flow model allows for an improved reliability of the one-dimensional code

Matrix product solution to an inhomogeneous multi-species TASEP

We study a multi-species exclusion process with inhomogeneous hopping rates. This model is equivalent to a Markov chain on the symmetric group that corresponds to a random walk in the affine braid arrangement. We find a matrix product representation for the stationary state of this model. We also show that it is equivalent to a graphical construction proposed by Ayyer and Linusson, which generalizes Ferrari and Martin's construction

Off-Critical SLE(2) and SLE(4): a Field Theory Approach

Using their relationship with the free boson and the free symplectic fermion, we study the off-critical perturbation of SLE(4) and SLE(2) obtained by adding a mass term to the action. We compute the off-critical statistics of the source in the Loewner equation describing the two dimensional interfaces. In these two cases we show that ratios of massive by massless partition functions, expressible as ratios of regularised determinants of massive and massless Laplacians, are (local) martingales for the massless interfaces. The off-critical drifts in the stochastic source of the Loewner equation are proportional to the logarithmic derivative of these ratios. We also show that massive correlation functions are (local) martingales for the massive interfaces. In the case of massive SLE(4), we use this property to prove a factorisation of the free boson measure.Comment: 30 pages, 1 figures, Published versio

Algebraic Bethe Ansatz for the two species ASEP with different hopping rates

An ASEP with two species of particles and different hopping rates is considered on a ring. Its integrability is proved and the Nested Algebraic Bethe Ansatz is used to derive the Bethe Equations for states with arbitrary numbers of particles of each type, generalizing the results of Derrida and Evans. We present also formulas for the total velocity of particles of a given type and their limit for large size of the system and finite densities of the particles.Comment: 14 page

HBIM challenge among the paradigm of complexity, tools and preservation: The Basilica di Collemaggio 8 years after the earthquake (L'Aquila)

In December 2012 ENIservizi (the Italian multi-national energy agency operating in many countries), after the Earthquake that occurred in April 2009, decided to undertake the project 'Re-start from Collemaggio' with the aim of giving new hope to the L'Aquila community, funding around 14 million Euro to restore the Basilica di Collemaggio. The Superintendence Office carried on the restoration project with the scientific support of the Università degli Studi de L'Aquila and the Università La Sapienza di Roma, under the coordination of the Politecnico di Milano. ENIservizi, aware of the BIM potential in the complex building and infrastructure domain in the world, required an advanced HBIM from the laser scanner and photogrammetric surveying to support the diagnostic analysis, the design project, the tender and the restoration itself, today still on course. Plans and vertical sections were delivered (2012) starting from the surveying campaigns (February and June 2013), together with the first HBIM advancement from the end of 2012 in support of the preliminary-definitive-executive steps of the restoration design project (2013-14-15). Five years later, this paper tries to make a synthesis of the different lessons learnt, in addition to the positive and critical aspects relating HBIM feasibility, sustainability and usefulness to the challenging restoration work. In particular, the Collemaggio BIM experience anticipated the new Italian Public Procurement Legislation (D.Lgs 50/2016, Nuovo Codice degli Appalti pubblici) aligned with to the EUPPD 24/2014: The EU Directive on Public Procurement asked all the 28 EU countries to adopt building informative modelling by February 2016 in order to support the whole LCM (Life Cycle Management), starting from the project and the intervention, through rewarding scores or mandatory regulations. Many analyses foresees to save from around 5% to 15% of the overall investment by adopting mature BIM (Level 3 to 5), particularly 4D remotely controlled BIM in support of the LCM, as in the case of maintenance and management process. The tender for Basilica restoration was published in 2015: The process was not developed enough to introduce selective criteria based on BIM adoption by the Construction Industry due to the lack of legislation at that time and the lack of BIM skills among the companies. Nevertheless ENIservizi also separately funded aside the HBIM of the Basilica to tackle an advanced BIM able to address decision-making processes in the heritage domain among the different actors: To support operators, architects, structural engineers, economic computation, construction site management and restoration, the theoretical and practical approach adopted by the HBIM, overcame the current logic based on sequential LoD (from simplex to complex, from the preliminary to the executive design) that is typical of new constructions in favour of a complex LoD approach that could guarantee management of the richness, unicity and multiplicity of each component and the maximum degree of knowledge in order to derive the decisions from the starting phases of the project. On the lesson learnt from this experience, the process of updating the current codification criteria (UNI11337-2009) was started with a draft proposal stimulating a debate for the future of HBIM adoption

THE MENSIOCHRONOLOGY ANALYSIS SUPPORTED BY NEW ADVANCED SURVEY TECHNIQUES: FIELD TESTS IN MILANESE AREA

Mensiochronology of brickwork, even in areas where reference curves have been constructed and well tested, requires precise measurements and a representative amount of data due to the many factors affecting the reliability of the measurements, such as the defects caused by the time and the environment that changed the geometry of the bricks (deformation or lack of material along the edges), as well as the operators’ skills. Sometimes, the number of measurable bricks is limited in a wall, or in a stratigraphic unit. Furthermore, if a scaffolding is not available, the analysis is concentrated only on the lower courses of the bricks, being not possible to directly measure the bricks of the higher levels. In order to implement the number of bricks taken into account for this study, a comparison from direct measurements and indirect measurements is here proposed.The aim of this paper is to explore the applications of photogrammetry for undertaking brick measurements for chronological dating: its advantage and drawbacks. Using high-resolution digital rectified pictures, the masonry texture of some well-documented building prospects was scaled into vector graphic software for recording the measures of the bricks. The results presented here by the authors are an attempt for validating this method for future applications. In detail, three case studies are analysed in the historic centre of Vimercate (Italy) testing the effectiveness of the presented method on dated buildings that display diverse features, including the presence of reused bricks, possibly coming from dismantled pre-existing structures. The results proved that the proposed geomatics method entails an accuracy that does not affect the usability of data for the investigation of buildings and the material culture inbuilt.</p