Polymer chain generation for coarse-grained models using radical-like polymerization

An innovative method is proposed to generate configurations of coarse grained models for polymer melts. This method, largely inspired by chemical ``radical polymerization'', is divided in three stages: (i) nucleation of radicals (reacting molecules caching monomers); (ii) growth of chains within a solvent of monomers; (iii) termination: annihilation of radicals and removal of residual monomers. The main interest of this method is that relaxation is performed as chains are generated. Pure mono and poly-disperse polymers melts are generated and compared to the configurations generated by the Push Off method from Auhl et al.. A detailed study of the static properties (gyration radius, mean square internal distance, entanglement length) confirms that the radical-like polymerization technics is suitable to generate equilibrated melts. The method is flexible, and can be adapted to generate nano-structured polymers, namely diblock and triblock copolymers.Comment: 9 pages, 12 figure

Finite-temperature geometric properties of the Kitaev honeycomb model

We study finite-temperature topological properties of the Kitaev’s spin-honeycomb model in the vortex-free sector with the use of the recently introduced mean Uhlmann curvature. We employ an appropriate fermionization procedure to study the system as a two-band p-wave superconductor described by a Bogoliubov–de Gennes Hamiltonian. This allows us to study relevant quantities such as Berry and mean Uhlmann curvatures in a simple setting. More specifically, we consider the spin honeycomb in the presence of an external magnetic field breaking time-reversal symmetry. The introduction of such an external perturbation opens up a gap in the phase of the system characterized by non-Abelian statistics. The resulting model belongs to a symmetry-protected class, so that the Uhlmann number can be analyzed. We first consider the Berry curvature on a particular evolution line over the phase diagram. The mean Uhlmann curvature and the Uhlmann number are then analyzed by assuming a thermal state. The mean Uhlmann curvature describes a crossover effect as temperature rises. In the trivial phase, a nonmonotonic dependence of the Uhlmann number, as temperature increases, is reported and explained

Vibrational states and disorder in continuously compressed model glasses

We present in this paper a numerical study of the vibrational eigenvectors of a two-dimensional amorphous material, previously deeply studied from the point of view of mechanical properties and vibrational eigen-frequencies [7-10]. Attention is paid here to the connection between the mechanical properties of this material in term of elastic heterogeneities (EH), and how these inherent heterogeneous structures affect the vibrational eigenvectors and their plane waves decomposition. The systems are analysed for different hydrostatic pressures, and using results from previous studies, a deeper understanding of the boson peak scenario is obtained. The vibrational spectrum of a continuously densified silica glass is also studied, from which it appears that the pulsation associated with the boson peak follows the same pressure dependence trend than that of transverse waves with pulsation associated with the EH characteristic size.Comment: 9 pages, 12 figure

Influence of the Thermophysical Model on the CFD Analysis of Oil-Cooled Transformer Windings

A disc-type winding of an oil-immersed power transformer is modeled with Computational Fluid Dynamics. Different approaches are implemented to evaluate the feasibility of the Boussinesq approximation: (i) constant fluid properties, (ii) variable viscosity and thermal diffusivity and (iii) temperature-dependent fluid properties. Temperature and flow distributions are reconstructed and put into relation with physical phenomena and model assumptions. Their comparison suggests that numerical results are fairly sensitive to the thermophysical model as long as the buoyancy force is a relevant component of the flow. Nonetheless, all the cases converge to very close predictions of the hot-spot value and location, with possibly positive implications for the use of reference parameters when deriving flow and heat transfer correlations for this topic

Strain localization and anisotropic correlations in a mesoscopic model of amorphous plasticity

A mesoscopic model for shear plasticity of amorphous materials in two dimensions is introduced, and studied through numerical simulations in order to elucidate the macroscopic (large scale) mechanical behavior. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete lattice, local reorganizations are modeled as local slip events. Local yield stresses are randomly distributed in space and invariant in time. Each plastic slip event induces a long-ranged elastic stress redistribution. Rate and thermal effects are not discussed in the present study. Extremal dynamics allows for recovering many of the complex features of amorphous plasticity observed experimentally and in numerical atomistic simulations in the quasi-static regime. In particular, a quantitative picture of localization, and of the anisotropic strain correlation both in the initial transient regime, and in the steady state are provided. In addition, the preparation of the amorphous sample is shown to have a crucial effect of on the localization behavior

Building-Integrated Photovoltaics in Existing Buildings: A Novel PV Roofing System

Among renewable energy generation technologies, photovoltaics has a pivotal role in reaching the EU's decarbonization goals. In particular, building-integrated photovoltaic (BIPV) systems are attracting increasing interest since they are a fundamental element that allows buildings to abate their CO2 emissions while also performing functions typical of traditional building components, such as sealing against water. In such a context, since one of the main challenges to decarbonizing the building sector lies in the retrofitting of existing buildings, the current paper is focused on the design, development, and testing of a novel roofing BIPV system. The entire research was carried out as part of the Horizon 2020 HEART project. In more detail, the research analyzed the requirements of typical pitched tile roofs, which are currently the most common type in Europe, and developed a universal photovoltaic tile that can be easily and quickly integrated into such a type of roof. The research was also aimed at minimizing the embodied energy of the component and promoting disassembly and recycling at the end of life, fully in line with a circular economy perspective. The adopted design and development processes are described in detail in the present paper, along with the results of several tests performed in the field. In addition, further development prospects of the component, aimed at meeting the integration requirements in historic buildings, are finally presented

Renovation of an UNESCO Heritage Settlement in Southern Italy: ASHP and BIPV for a "Spread Hotel" Project☆

Abstract Many small historical settlements in Mediterranean areas have a great value in terms of architectural and cultural heritage. Therefore it happens that the socio–economic situation of many of these settlements is backward and depressed. A succesful way to develop these important environments is to implement tourism, a profitable and available economical resource. "Spread Hotel" or "Diffuse Hotel" or "Albergo Diffuso" is an innovative concept which aims to renovate decayed buildings situated in historical locations. New economical inputs are needed to revitalize these settlements and their social tissue. "Diffuse Hotel" concept is very diffused in Italy due to its rich historical heritage. The present paper displays a renovation project of a rural historical settlement into a "Spread Hotel". The site under analysis is located in Palazzolo Acreide, Sicily, Italy. The settlement strongly needed to be refurbished in order to provide habitability and to guarantee a proper level of comfort according to italian standards. The area is also listed in the UNESCO Heritage. The "Diffuse Hotel" at a national level is considered as an affordable and comfortable concept that enables the travellers to experiance Italy through a tipical, historical and comfortable hotel. The historical built enviroment preservation is strategic in Italy and can strongly support economical revitalization. European Community supports the development of "Spread Hotels" projects in order to improve economical capacity of depressed areas by financing refurbishment programs. In this contest the authors present how "Palazzolo Acreide" renovation project was done. In particular, the design strategy was to respect the local characteristics, improve thermal performance and HVAC systems and exploting the on site renewable energy. In fact, in the Mediterranean areas solar radiation is a incredible resource to provide energy to the buildings

water pvt collectors performance comparison

Abstract Flat plate PVT water based technology presents many advantages in terms of overall performance and space saving than the PV modules and the solar thermal collectors installed separately. However, the electrical and the thermal performances of the PVT technologies are more deeply related to different influences factors, among which: the presence or absence of the air gap formed by the transparent frontal cover, the absorber configuration and the adopted PV technology. For that reasons, the proposed research is aimed to assess, under the energy point of view, a comparison between a covered and an uncovered PVT water collectors, realized with different PV cells coupled to two aluminium roll-bond absorbers characterized also by different channel arrangements. The performance analysis is based on energy simulations carried out with two mathematical models validated on experimental data at the Test Facility of the Politecnico di Milano

Arte e multiculturalidade : o caso do parque escultórico “vía christi" de Junín de los Andes – Neuquén

Este trabajo tiene como objetivo problematizar la relación entre arte e interculturalidad a partir del análisis del llamado Parque Escultórico Vía Christi. En este caso, nos interesa realizar un primer acercamiento al término interculturalidad para descubrir los diversos sentidos que surgen en el discurso de nuestros entrevistados. El Vía Christi es un paseo turístico-religioso que se encuentra en el Cerro de la Cruz de la ciudad de Junín de Los Andes de la provincia de Neuquén. Está compuesto de veintidós estaciones, a modo de grupos escultóricos, que relatan la “vida" o camino de Cristo, y no el habitual calvario de pasión y muerte. Las mismas se extienden a lo largo de un recorrido de dos quilómetros. El proyecto iniciado hacia 1998, parte de las Hermanas de María Auxiliadora (rama femenina de la congregación salesiana con una larga trayectoria en la región) quienes conformaron un grupo de trabajo integrado por clérigos, autoridades municipales, pobladores, artistas locales y el arquitecto Alejandro Santana, director de la obra. A partir de entrevistas personales con las religiosas el parque es considerado un verdadero ejemplo de “interculturalidad, interreligiosidad e identidad latinoamericana". No nos enfocamos en un análisis plástico – formal de la obra de arte, sino que a partir del trabajo de campo y el análisis bibliográfico nos proponemos como objetivo principal conocer la pluralidad de significaciones de los actores implicados (representantes municipales, de la iglesia, de la comunidad mapuche de Junín de Los Andes y artistas plásticos) en el proceso de concepción y ejecución de la obra que fundamentan o no al Vía Christi como una expresión artística de carácter intercultural. La observación in situ y las entrevistas personales, trabajos que aun se están llevando a cabo, resultan de vital importancia, ya que no se trata de un mero concepto teórico, sino de una realidad en curso que se da en forma práctica e inexorable, pero que adquiere diferentes usos y posee distintas significaciones según los contextos y lugares de enunciación, con implicancias profundas.This work aims to problematize the relationship between art and multiculturalism from the analysis of so-called Via Christi Sculpture Park. In this case, we want to make a first approach to the term multiculturalism to discover the different meanings that arise from our interviewees’ statements. The Via Christi is a tourist-religious walk which is located in the Cerro de la Cruz town of Junín de Los Andes in the province of Neuquén. It consists of twenty-two stations with sculptures, which tell the "life" or way of Christ, and not the usual ordeal of suffering and death. They extend over a distance of two kilometers. The project started around 1998 by the Sisters of Mary Help of Christians (female branch of the Salesian Congregation with a long history in the region) who formed a working group composed of clerics, city officials, residents, local artists and architect Alejandro Santana, director of the work. From personal interviews to the Sisters, the park is considered a true example of "intercultural, interreligious and Latin American identity." We do not focus on a formal plastic analysis of the work of art. Instead, from the fieldwork and based on the existing literature, we propose as main objective to know the plurality of meanings of the actors involved -representatives of the municipality, of the church, of the the Mapuche community of Junín de Los Andes and artists- in the conception and execution of the work which may or may not validate the Via Christi as an artistic expression of intercultural character. The in situ and personal interviews are of vital importance, since it is not merely a theoretical concept, but an underway reality that cannot be stopped from happening, but that acquires different uses and has different meanings in different contexts and places of enunciation, with profound implications.A observação in situ e as entrevistas pessoais, trabalhos que ainda estão se levando a cabo, resultam de vital importância, já que não se trata de uma realidade em curso que se dá em forma prática inexorável, mas que adquire diferentes usos e possui distintas significações segundo os contextos e lugares de enunciação, com implicâncias profundas. Este trabalho tem como objetivo problematizar a relação entre arte e interculturalidade a partir da análise do chamado Parque Escultórico Vía Christi. Neste caso, nos interessa realizar uma primeira aproximação ao termo multiculturalidade para descobrir os diversos sentidos que surgem no discurso de nossos entrevistados. O Vía Christi é um passeio turístico-religioso que se localiza na cidade de Junín de Los Andes da província de Neuquén. Está composto de vinte e dois estações, a modo de grupos escultóricos que relatam a “vida" o caminho de Cristo, e não o habitual calvário de paixão e morte. As mesmas se estendem numa longitude de dois kilômetros. O projeto inciado por volta de 1998, além das Ferramentas de Maria Auxiliadora (parte feminina da congregação salesiana com uma extensa trajetória na religião) quem conformaram um grupo de trabalho integrado por clérigos, autoridades municipais, povoadores, artistas locais e o arquiteto Alejandro Santana, diretor da obra. A partir de entrevistas pessoais com as religiosas o parque é considerado um verdadeiro exemplo de “multiculturalidade, interreligiosidade e identidade latino-americana". Não nos enfocamos em uma análise plástico – formal da obra de arte, sendo que a partir do trabalho de campo e da análise bibliográfica nos propomos como objetivo principal conhecer a pluralidade de significações dos atores implicados (representantes municipais, da igreja, da comunidade mapuche de Junín de los Andes e artistas plásticos) no processo de concepção e execução da obra que fundamentam não ao Vía Christi com uma expressão artística de caráter multicultural.Fil: Leonforte, Andrea. Universidad Nacional de Cuyo. Facultad de Filosofía y Letras. Instituto de Historia del Art

Plastic Response of a 2D Lennard-Jones amorphous solid: Detailed analysis of the local rearrangements at very slow strain-rate

We analyze in details the atomistic response of a model amorphous material submitted to plastic shear in the athermal, quasistatic limit. After a linear stress-strain behavior, the system undergoes a noisy plastic flow. We show that the plastic flow is spatially heterogeneous. Two kinds of plastic events occur in the system: quadrupolar localized rearrangements, and shear bands. The analysis of the individual motion of a particle shows also two regimes: a hyper-diffusive regime followed by a diffusive regime, even at zero temperature