DSpace Collezione: DINCI
https://hdl.handle.net/10955/99
DINCI2024-03-01T16:07:43ZThe quality of air transport service
https://hdl.handle.net/10955/5443
Titolo: The quality of air transport service
Autori: Bellizzi, Maria Grazia; Conte, Enrico; Eboli, Laura
Abstract: The socioeconomic development of a country necessarily relies on the
improvement of all transport services. With the introduction of new
technologies, transport industry has developed considerably in recent years,
and as a consequence people habits and travel choices changed as well. In
this context, air transport has a significant role, and it could be considered
one of the most significant contributors to the advancement of modern
society.
Evaluating air transport service quality is important as it is for the other
public transport systems. Airport facilities and services are the first
experiences that a passenger receives upon arrival. For this reason, providing
airport services characterized by high levels of quality is very important to
make the travel more pleasant for the passengers, with the final objective to
attract more users. Therefore, measuring the levels of airport services by
evaluating passengers’ satisfaction with them is essential to understand the
needs of customers. In the same way, with the airlines’ deregulation the
number of airlines entered into the air transport industry significantly
increased, causing a stronger competition. In this context, it is evident that
provided service quality, as well as passengers’ satisfaction, play an
important role also in the airlines marketing strategies.
While literature regarding the evaluation of road and rail public transport
service quality is well established from many years, literature concerning air transport service quality is relatively recent. A first substantial issue that
emerges from the air transport related literature concerns the complexity of
the various characteristics of the services, which can relate to the airport
managing companies and to the airlines. For this reason, the major part of
the studies treats separately these two groups of service. Specifically, the
researchers analysed air transport services by distinguishing the concerning the services offered in the airports from the ones provided by the
airlines.
The aim of this thesis work is to give a contribution to the existing
literature, by applying various techniques and models for analysing both
airport and airlines’ service quality. As suggested by the literature, also in
this work the airport services have been treated separately by the airlines’
services. In fact, two different data samples were analysed. Specifically, the
International airport of Lamezia Terme (Italy) has been considered as case
study for the airport services. Otherwise, data collected by an online survey
conducted at the University of Calabria (Italy) became object of study for the
airlines’ services analyses. Several tools have been tested and proposed. The
obtained results could be considered not only as a research contribution, but
also as starting point to help air transport managers and providers in choosing
the effective strategy for providing services characterized by adequate levels
of quality.
Descrizione: Dottorato di ricerca in Ingegneria civile e industriale. Ciclo XXXIII2021-03-25T00:00:00ZNew one-line model for shoreline evolution at beaches composed of not cohesive grains of any size
https://hdl.handle.net/10955/5434
Titolo: New one-line model for shoreline evolution at beaches composed of not cohesive grains of any size
Autori: Francone, Antonio; Furgiuele, Franco; Tomasicchio, Giuseppe Roberto; Frega, Ferdinando
Abstract: Over recent decades, efforts have been made to find robust methods for predicting shoreline
evolution near to the coastal structures. This requires a rigorous understanding of the key coastal
processes that drive sediment transport, and how they are impacted by the presence of structures.
Once this understanding is reached, a method for predicting morphological shoreline evolution is
required. In this context, numerical modelling plays an important role.
A new one-line model for shoreline evolution at beaches composed of not cohesive grains of any
size is proposed: the General Shoreline beach (GSb). GSb model is based on the one-line theory, for
which it is assumed that the equilibrium beach profile remains unchanged (Dean, 1990), thereby
allowing beach change to be described uniquely in terms of the shoreline position. The longshore
sediment transport rate is estimated by means of a general formula/procedure (Tomasicchio et al.,
1994; Lamberti and Tomasicchio, 1997; Tomasicchio et al., 2013; Tomasicchio et al., 2015)
combining an energy flux approach with an empirical/statistical relationship between the waveinduced
forcing and the number of moving units.
The uniqueness of the proposed new one-line model consists in the possibility to simulate beach
change, including the effects of coastal structures (i.e. groynes, detached breakwaters), at a mound
composed of not cohesive grains of any size, from sand to rock units.
Despite other existing models, the GSb model presents a calibration factor, KGSb solely and it has
been calibrated and verified against field and laboratory data on sandy and mixed beach (sand and
gravel) referring to simple groyne and detached breakwater (Ming and Chiew, 2000; Hamilton et al.,
2001; Martin-Grandes et al., 2009; Medellin et al., 2018;). Optimal values of KGSb, valid for different
types of not cohesive grains and coastal structures, have been reported.
It is showed that the GSb model can be considered a reliable engineering tool to conduct
morphodynamics studies. A demo version of the GSb model, for Mac and Windows systems, has
been released for the scientific community and is available at www.scacr.eu.
Descrizione: Dottorato di Ricerca in Ingegneria Civile e Industriale - Ciclo XXXII2020-02-18T00:00:00ZAnalisi del comportamento non-lineare dei materiali compositi con microstruttura periodica
https://hdl.handle.net/10955/5412
Titolo: Analisi del comportamento non-lineare dei materiali compositi con microstruttura periodica
Autori: Sgambittera, Girolamo; Olivito, Renato Sante; Bruno, Domenico; Greco, Fabrizio
Abstract: In the present thesis the macroscopic non-linear behavior of composite materials with a
periodic and heterogeneous microstructure is studied. There are many different kinds of
phenomena that produce non-linear effects in composite materials, for example
intralaminar damage, delamination and microbucking in fiber reinforced composite or
micro-cracking in cellular materials. In this work attention is devoted to the mechanical
modeling of nonlinear phenomena associated to the presence of micro-cracks in the
context of linear elasticity and of microscopic instabilities in the framework of the
finite strain theory. Applications have been developed with reference to microstructures
of cellular type and with embedded inclusions. The thesis is structured according to the
following chapters:
-In the first chapter the fundamental concepts of the finite strains theory are recalled.
The constitutive relations associated to a class of conjugate stress-strain pairs are
introduced. The basic expressions of the incremental constitutive laws are shown with
special reference to incrementally linear constitutive laws. Finally the stability and the
uniqueness of the equilibrium solution are analyzed.
-In the second chapter, after an introduction about the homogenization techniques, the
micro and macro stability phenomena occurring in composite materials with a periodic
microstructure are studied from a theoretical point of view in the context of the finite
strains theory. The formulation starts from a variational formulation of the problem.
Novel macroscopic measures of micro-structural stability are introduced corresponding
to the positive definiteness of the homogenized moduli tensors relative to a class of
conjugate stress-strain pairs and their effectiveness to obtain a conservative prediction
of the microscopic primary instability load is pointed out. Analysis of these stability phenomena plays a fundamental role because often the
collapse of composite materials with periodic microstructure is related to
microstructural instabilities. In addition the microscopic stability analysis establishes
the region of validity of the standard homogenization procedure based on the unit cell
procedure.
-In the third chapter, in the context of the small strains theory, non-linear phenomena
are presented with reference to composite materials with a porous microstructure
containing micro-cracks spreading from the voids. The fundamental techniques of
homogenization are applied in conjunction with fracture mechanics theory and interface
models. The energy release rate is evaluated through the J-integral technique. -In the fourth chapter some numerical applications carried out by means of a one-way
coupled finite element code, are proposed.
In the first section the numerical results will be introduced with reference to the
theoretical aspects developed in the second chapter. Numerical analyses are addressed
to composite materials with a periodic microstructure, namely a porous microstructure
and a particle-reinforced microstructure. The adopted constitutive law is hyperelastic.
Periodic boundary conditions will be used for the microstructure, and uniaxial and
equibiaxial loading conditions are considered. Numerical analyses are able to show the
exact region of microscopic stability, obtained by taking into account all the microstructural
details, and the region of macroscopic stability, determinate by studying
homogenized material properties.
To elaborate macroscopic criteria able to give a conservative prediction of the
microstructural stability, different measures of macroscopic instability are introduced
with reference to work conjugate strain-stress measures.
In the second section of this chapter a numerical analyses with reference to the micromechanical model proposed in the third chapter is developed. In this case the
microstructure adopted for the composite materials is a cellular microstructure in which
there is the presence of two micro-cracks advancing symmetrically from the void. The
microstructure is subjected to three different boundary conditions namely respectively:
linear displacements, periodic fluctuations and antiperiodic tractions and uniform
tractions. The objective of this section is to verify the validity of the homogenization technique in
the prediction of micro-crack evolution phenomena, for composites with locally
periodic microstructure.
The energy release rate obtained through the micromechanical model will be compared
with a 2D composite structure composed by a regular arrangement of 5x5 unit cells. The
composite structure is subjected to two different boundary conditions: the former is
associated with the absence of contact between the surfaces of the micro-cracks, on the
contrary in the latter case there is the presence of the contact. This type of comparison
allows to investigate the accuracy of the proposed procedure in presence of macroscopic
tension and strain gradients.
Descrizione: Dipartimento di Strutture, Dottorato di Ricerca in Ingegneria dei Materiali e delle Strutture, Ciclo XXII2009-01-01T00:00:00Z40° N sole e contesto nella progettazione di spazi urbani mediterranei
https://hdl.handle.net/10955/5411
Titolo: 40° N sole e contesto nella progettazione di spazi urbani mediterranei
Autori: Carbone, Ivana; Rossi, Franco; Cannavò, Paola
Descrizione: PhD in Architecture and Urbanism2009-01-01T00:00:00Z