DIISM

In this paper, a finite element numerical algorithm for the simulation of two-dimensional problems of heat transfer with phase change is validated, comparing the numerical results with the experimental ones deriving from tests carried out on two different kinds of PCM containing sandwich panels. The very good approximation affecting the numerical results, as compared with the experimental ones, suggests that it can be a powerful design tool for every kind of PCM containing building elements.

The internationally recognized procedure ISO 354:2003 for measuring sound absorption coefficients under diffuse field conditions is now under revision. The main reason for this revision is the limited reproducibility of absorption coefficients measured in different laboratories that may have significant implications spanning from room acoustic design to material selection. A network of Italian laboratories have come together to carry out an Inter-Laboratory Test (ILT) to assess and compare the measurement uncertainties resulting from the application of the current version of ISO 354:2003 and of the new ISO/CD 354:2019. After detailing the methodological aspects, the paper presents the results of the measurements, discussing the compliance of the laboratories to the standard requirements and new qualification tests, and, more importantly, providing a quantitative estimation of their effects on measurement uncertainty and accuracy.

This paper describes the design principles underlying the Round Robin Test (RRT) carried out among the laboratories of the Sound Absorption working group of the Italian Standardization Body (UNI). In recent years, the determination of the measurement uncertainties in the fields of building and room acoustics has attracted increasing attention. In particular, sound absorption in a diffuse sound field might be difficult to determine, especially for very highly absorptive materials. Results coming from different laboratories cannot always be compared, due to differences in the actual sound field found in nominally equivalent facilities. During this RRT, carefully selected samples have been measured in the reverberation rooms of the different laboratories participating in the RRT according to standard ISO 354 in force as well as the newly proposed draft. The procedure will be presented in the paper.

Today, the art of knowing how to listen is more urgent than ever. The perceptive sound system of the human being is stimulated daily by countless artificial sounds that dominate natural ones. When it comes to the idea of the soundscape, the terminology was initially referred to by composer and environmentalist Raymond Murray Shafer, who defined “soundscape” as a relationship between the ear, humans, built environments, and society. This paper aims to apply the sound landscape approach in the seaport area of Ancona (Italy); a large area, frequented daily by many people, which is divided into passenger and ferry terminals, container terminals, plants for solid bulk, and commercial and recreational activities. The purpose of the study was to evaluate the perception that a human has of the urban layout of the port area by correlating the parameters of traditional acoustics with psychoacoustics. To evaluate the subjective parameters, a questionnaire was developed and applied, enabling th...

There is a growing scientific consensus that COVID-19 could be transmitted through the airborne route, putting ventilation at the heart of a mitigation strategy for buildings, including schools. The design of suitable systems requires to consider all aspects both for the control of air movement and the diffusion of bacterial loads, but also of other parameters of indoor air quality. This work examines the acoustic design of ventilation systems in schools and the effects that the systems have on the acoustic quality of the classrooms in compliance with the standard series UNI 11532. The standards provide a guideline on the design and the evaluation of the acoustic performances of schools, including attention for children with special educational needs. In particular, the case study refers to classrooms in the University Politecnica delle Marche, Ancona

The review of trends in farm practices and machinery development suggests that noise problems are still prevalent in agricultural situations. The aim of this study is to assess the noise exposure for workers during olive harvest in Azienda Agraria Didattico-Sperimentale of Universita Politecnica delle Marche. A monitoring of noise levels is conducted in some days of the years 2010-2011. Noise samplings were carried out on electric and pneumatic harvesters. For sound pressure levels measurements an integrating-averaging sound-level meter, B&K2250 type, was used and the measurement procedure was set up in accordance with ISO 9612:2011. The tests have been carried out during the regular working activity with all the shakers operated by the same worker expert in the use of this machines. The results allowed to evaluate noise exposure during the olive harvest. Every machine has been analyzed to establish the level of noise produced according to the laws in force. With the collected data ...

The paper is focused on exposure to vibration during the olive harvest for farmers of Azienda Agraria of Universita Politecnica of Marche to highlight the importance of the exposure to vibrations transmitted to the hand-arm system in agriculture and its consequences on human health. To assess the exposure to mechanical vibration transmitted to operators during the olive harvest, measurements were done using a vibration measuring equipment during the regular working activity. The vibration samplings were carried out on electric and pneumatic harvesters. The measured data were compared with the prevention values for the safety requirements fixed by the normative. The analysis of the results shows that the electric harvesters transmit vibrations equivalent and in some cases higher than ones provided by the pneumatic harvesters. The paper, evaluating the risk to the hand-arm system due to vibrations, give an overview of the exposure of workers to the risks arising from vibrations to whi...

Heating ventilation and air conditioning (HVAC) systems represent one of the main noise sources inside classrooms. This explain why HVAC systems require careful design, competent installation and balancing, and regular maintenance. Many factors influence the classroom acoustical design, such as air handlers or fans, the velocity of air inside the classroom, as well as the size and acoustical treatment of ducts, returns, and diffusers. Acoustic parameters, including background-noise levels, reverberation time, and intelligibility, were analyzed in 17 classrooms at the Università Politecnica in the Marche region. The study of intelligibility was performed by measuring the objective parameters in situ and using prediction methods to determine the intelligibility score. The relationship between speech intelligibility measurements and speech intelligibility calculation has been studied. The relationship between the STI values with the background-noise levels and the reverberation time wa...

A closed 3-manifold M is said to be hyperelliptic if it has an involution τ such that the quotient space of M by the action of τ is homeomorphic to the standard 3-sphere. We show that the hyperbolic football manifolds of Emil Molnár [12] are hyperelliptic. Then we determine the isometry groups of such manifolds. Another consequence is that the unique hyperbolic dodecahedral and icosahedral 3-space forms with rst homology group Z 35 (constructed by I. Prok in [16], on the basis of a principal algorithm due to Emil Molnár [13], and by Richardson and Rubinstein in [18]) are also hyperelliptic.

The problem of classifying, up to isometry, the orientable 3-manifolds that arise by identifying the faces of a Platonic solid was completely solved in a nice paper of Everitt [B. Everitt, 3-manifolds from Platonic solids, Topology Appl. 138 253-263]. His work completes the classification begun by Best [L.A. Best, On torsion-free discrete subgroups of PSL 2 (C) with compact orbit space, Canad. J. Math. 23 (1971) 451-460], Lorimer [P.J. Lorimer, Four dodecahedral spaces, Pacific J. Math. 156 (2) (1992) 329-335], Prok [I. Prok, Classification of dodecahedral space forms, Beiträge Algebra Geom. 39 (2) (1998) 497-515], and Richardson and Rubinstein [J. Richardson, J.H. Rubinstein, Hyperbolic manifolds from a regular polyhedron, Preprint]

We construct some hyperbolic hyperelliptic space forms whose fundamental groups are generated by only two or three isometries. Each occurring group is obtained from a supergroup, which is an extended Coxeter group generated by plane reflections and half-turns. Then we describe covering properties and determine the isometry groups of the constructed manifolds. Furthermore, we give an explicit construction of space form of the second smallest volume nonorientable hyperbolic 3manifold with one cusp.

We determine certain exceptional surgeries on a 3-parametric family of hyperbolic 1-bridge genus one knots ((1, 1)-knots, in short). In particular, we show that such knots admit two infinite series of lens space surgeries. Our work is related to a nice paper of Teragaito [16], since we represent his toroidal manifolds as 2-fold coverings of the 3-sphere branched over well-specified links.

We obtain the Smith normal forms of a class of circulant polynomial matrices (λ-matrices) in terms of their "associated polynomials" when these polynomials do not have repeated roots. We apply this to the case when the associated polynomials are products of cyclotomic polynomials and show that the entries of the Smith normal form are products of cyclotomics.

We study a family of closed connected orientable 3-manifolds obtained by Dehn surgeries with rational coefficients along the oriented components of certain links. This family contains all the manifolds obtained by surgery along the (hyperbolic) 2-bridge knots. We find geometric presentations for the fundamental group of such manifolds and represent them as branched covering spaces. As a consequence, we prove that the surgery manifolds, arising from the hyperbolic 2-bridge knots, have Heegaard genus 2 and are 2-fold coverings of the 3-sphere branched over well-specified links.

We determine certain exceptional surgeries on a 3-parametric family of hyperbolic 1-bridge genus one knots ((1, 1)-knots, in short). In particular, we show that such knots admit two infinite series of lens space surgeries. Our work is related to a nice paper of Teragaito [16], since we represent his toroidal manifolds as 2-fold coverings of the 3-sphere branched over well-specified links.

We determine certain exceptional surgeries on a 3-parametric family of hyperbolic 1-bridge genus one knots ((1, 1)-knots, in short). In p articular, we show that such knots admit two infinite series of lens space surgeries. Our work is related to a nice paper of Teragaito [16], since we represent his toroidal manifolds as 2-fold coverings of the 3-sphere branched over well-specified link s.

We construct a family of closed 3-manifolds Mα,r, which are homeomorphic to the Brieskorn homology spheres Σ(2, α+1, q +2r−1), where q = α(r−1) and both α ≥ 1 and q ≥ 3 are odd. We show that Mα,r can be represented as 2-fold covering of the 3-sphere branched over two inequivalent knots. Our proofs follow immediately from two different symmetries of a genus 2 Heegaard diagram of Σ(2, α + 1, q + 2r − 1), and generalize analogous results proved in [BGM], [IK], [SIK] and [T].