1,837 research outputs found
Comparison of experimental and numerical sloshing loads in partially filled tanks
No full textSloshing phenomenon consists in the movement of liquids inside partially filled tanks, whichgenerates dynamic loads on the tank structure. Resulting impact pressures are of great importance in assessingstructural strength, and their correct evaluation still represents a challenge for the designer due to the highnonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of airtrapping. In the present paper a set of two-dimensional cases for which experimental results are available areconsidered to assess merits and shortcomings of different numerical methods for sloshing evaluation, namely twocommercial RANS solvers (FLOW-3D and LS-DYNA), and two own developed methods (Smoothed ParticleHydrodynamics and RANS). Impact pressures at different critical locations and global moment induced by watermotion for a partially filled tank with rectangular section having a rolling motion have been evaluated and resultsare compared with experiments
Il libro dello spreco. Sullo stile tardo di Italo Calvino
No full textIn 1967 Italo Calvino moved to Paris and programmatically decided to enter into his old age. This choice also influences the style of his following narrative production. In this perspective, my essay faces the novel If on a Winter’s Night a Traveler looking at the notion of late style coined by Theodor W. Adorno, which assumes the closeness of the death to the author as the cause of a divergence between artistic conventions and his subjectivity. I will try to show how the formal waste of the selfless virtuosic novel actually reflects its author’s ethics of difficulty. According to Calvino everything, men and books, needs to be justified by a project that implies «voluntary choices» and «active renunciations».Il contributo intende analizzare Se una notte d’inverno un viaggiatore come prodotto della stagione senile di Calvino, cominciata programmaticamente con il trasferimento a Parigi del 1967. In particolare, nel romanzo si può riconoscere la divaricazione tra convenzioni artistiche e soggettività dell’autore, innescata dall’approssimarsi della morte, su cui Adorno fondava il concetto di stile tardo. Si cercherà di mostrare come lo spreco formale del romanzo senza self, virtuosistico e barocco, rispecchi in realtà l’etica del difficile del suo autore, per il quale ogni cosa, uomini e libri, va giustificata all’interno di un progetto fatto di «scelte volontarie» e di «rinunce attive»
Chrześcijański kult świętych i ich relikwii wciąż żywy. Turyński relikwiarz świętego Dominika Savio
No full textThe author of this article drew attention that the Christian cult of saints and their relics is still valid. This article was created on the occasion of the 160th anniversary of the death of St. Dominic Savio and the 10th anniversary of the pilgrimage his reliquary in Poland. The author of this study believes that the latter event confirms this thesis.Chrześcijański kult świętych i ich relikwii wciąż żywy. Turyński relikwiarz świętego Dominika Savio. Autor tego artykułu zwrócił uwagę, że chrześcijański kult świętych i ich relikwii jest wciąż aktualny. Artykuł powstał z okazji 160. rocznicy śmierci świętego Dominika Savio i 10. rocznicy peregrynacji jego relikwiarza w Polsce. Autor tego opracowania uważa, że to drugie wydarzenie potwierdza tytułowe założenie
Perdere le radici. Appunti sulla modernità di Italo Calvino
No full textL’articolo intende sviluppare alcune considerazioni sul rapporto tra il mito identitario delle radici e l’opera di Italo Calvino, nel contesto della modernità letteraria e in particolare del ventesimo secolo. L’analisi si concentrerà su testi come ‘La speculazione edilizia’, ‘La strada di San Giovanni’, ‘Dall’opaco’ e ‘Il museo dei formaggi’. Cercherò di mettere in luce la postura di Calvino in relazione al territorio ligure da cui proviene, e più in generale proverò a dimostrare come l’autore sia immune a qualsiasi nostalgia consolatoria o regressiva. L’idea di fondo è che Calvino non trasformi il passato in un mito di appartenenza etnico-geografica: il suo metodo archeologico cerca invece di processare la ‘diversità contemporanea delle culture umane’ (Marc Augé), prendendo atto di come la modernità abbia cancellato ogni illusione di permanenza e di stabilità antropologica.The article intends to develop some considerations on the relationship between the identity myth of roots and the work of Italo Calvino, within the framework of literary modernity and in particular of the Twentieth Century. The analysis will focus on texts such as ‘La speculazione edilizia’, ‘La strada di San Giovanni’, ‘Dall'opaco’ and ‘Il museo dei formaggi’. I will try to highlight Calvino's posture in relation with the Ligurian territory from which he comes, and more generally I will try to demonstrate how the author is resistant to any comforting or regressive nostalgia. The basic idea is that Calvino does not make use of the past as a myth of geographic-ethnic belonging: his archaeological method instead tries to process the ‘contemporary diversity of human cultures’ (Marc Augé), taking note of how modernity has cancelled any illusion of permanence and anthropological stability
From Security to Localization: Advanced Services for Large-Scale IoT Networks
No full textThis PhD disseration is focused on the topic of Internet of Things (IoT) technology, with specific focus on security issues and localization functionalities in IoT deployments composed by many constrained devices.
In fact, the last decade has been the witness of the explosion of the IoT, and today billions of smart devices are hitting the market. They are equipped with sensing and actuating capabilities and they have the capabilities to interact between them over the Internet. This phenomenon paves the way to a variety of innovative applications in different contexts, such as environmental monitoring, smart building, home automation, health care, logistics and energy management, to name a few. Moreover, the innovations provided by such technological evolution especially in industrial applications is currently enabling a wide set of advanced services, indicated as the forth industrial revolution, Industry 4.0, that will leverage on the new specific paradigm of the, Industrial Internet of Things (IIoT). Also, the major leading companies of the sector expect up to 50 billion of smart devices connected by 2020.
In this ebullient context, the need for developing accurate and tailored services, resized on the requirements and features of the constrained devices at the basis of IoT technology, is still an incumbent hurdle.
From one side, security aspects stand in a prominent position. In fact, the unique features of the involved devices require the design of tailored routines and protocols, able to minimally affect the regular communications, operations and the execution of the standard protocol stack.
From the other side, the deployment of mobile sensor nodes requires the presence of smart and lightweight static and dynamic localization techniques, able to provide instant-by-instant the position of the sensing entities, without affecting the execution of their fundamental tasks and the lifetime of battery-powered devices.
Starting from these premises, the present PhD thesis wraps around the main topic of providing advanced services for IoT networks, with the aim of affecting the normal network operations only in a minimal part.
With the focus on security aspects, the procedures and services recommended by one of the most important standard for IoT protocol stack, IEEE 802.15.4e, have been implemented. The overhead of link-layer security in IIoT networks has been evaluated, in terms of minimal timeslot length and memory footprint. The provided implementation of link-layer security covers a range of hardware platforms, exploring different hardware/software implementation strategies. Through an extensive measurement campaign, the advantage of hardware accelerators for link-layer security have been precisely quantified. Furthermore, the impact that the resulting timeslot duration has on both high-level application design and energy consumption have been investigated.
Moreover, starting from a careful inquiry about the gaps left open by the MAC layer standard IEEE 802.15.4, a lightweight and standard compatible framework, namely “LICITUS”, has been developed, with the aim of providing a wide variety of security configurations in homogeneous and heterogeneous scenarios, integration support for adaptation to dynamic networks, lean and scalable initialization functionalities, a lightweight Key Management Protocol (KMP) and resilience to several attacks.
Starting from the KMP developed in the LICITUS framework, an advanced version has been designed. It integrates implicit Elliptic Curve Qu-Vanstone (ECQV) certificates with a standard Elliptic Curve Diffie-Hellman (ECDH) exchange. From a security perspective, it performs authentication and key derivation between any two peers an IIoT network. As confirmed by a proof-of-concept implementation and relevant experimental results, this innovative KMP guarantees the minimal airtime consumption with respect to conventional approaches, while providing also robust key negotiation, fast re-keying, and efficient protection against replay attacks.
The research activity about security has also covered the authorization problem, which is quickly emerging as one of the most important barrier to protect against external threats coming from the public Internet. Within the context of the symbIoTe H2020 European project, an authorization architecture based on the widely known OAuth 2.0 authorization framework has been proposed. Thanks to security services provided by the OAuth 2.0 Authorization Server deployed at the edge of the IoT network, the proposed solution assures the precise identification of all accesses to resources exposed by the smart devices, while not affecting in any way their computational burden.
As regarding localization solutions, a 4-months period of research abroad at the Faculty of Computer and Information Science in Ljubljana (Slovenia) have been conducted to study and provide a lightweight off-line algorithm that addresses the problem of estimating the position and velocity of a radio transmitter moving with a constant, unknown speed. The provided technique is based on arrival timestamps gathered by fixed sensor nodes. The technique is completely asynchronous in its logic, because no assumption is made about any time synchronization between the involved devices. The performances of this solution have been investigated not only through a wide set of Monte-Carlo simulations, but also by using real data provided by off-the-shelf Wi-Fi devices, demonstrating its feasibility for adoption in specific IoT services.
To conclude, a brief description of the structure of the thesis is provided below:
1. Chapter 1: The Internet of Things technology. It introduces the main features of the upcoming IoT technology, with a focus on the standardized protocol stack and the variety of hardware devices specifically designed for such applications.
2. Chapter 2: Security issues in IoT networks. It provides an extensive summary of the state of the art in the IoT security area, discussing the most adopted solutions and algorithms.
3. Chapter 3: MAC-layer security in IoT networks. In this chapter the implementation of security procedures, services and algorithm recommended by the IEEE 802.15.4 standard is detailed, as well as a lightweight security framework that integrates and smartly uses such services.
4. Chapter 4: Security solutions at the application layer for the IoT. It discusses the solutions specifically designed to address security issues at the application layer, starting from a lightweight KMP guaranteeing the minimal airtime consumption, up to advanced solutions addressing the authorization problem.
5. Chapter 5: Time-based wireless localization techniques. It focuses on an algorithm developed to estimate the position and velocity of a node moving at a constant, unknown velocity. The performance evaluation of the algorithm is described, both in a simulated environment and through real Wi-Fi data, along with the advantages derived by its adoption in the IoT context
L'attuazione della seconda direttiva comunitaria e il nuovo ordinamento dell'attività bancaria. Il decreto legislativo 481/92
No full textUn viaje desde Oriente al Occidente: el Pileus, del gorro de los Dioscuros al simbolo de la Libertad
No full textAnalytical solution of the bond behavior of FRCM composites using a rigid-softening cohesive material law
No full textThe study of the bond behavior of fiber-reinforced composite materials applied to cohesive substrates is a fundamental topic to correctly understand the composite-substrate stress-transfer mechanism. Bond tests of fiber reinforced cementitious matrix (FRCM) composites comprising one layer of fiber textile generally showed failure due to debonding of the textile at the matrix-fiber interface. This failure mode was described considering a fracture mechanics pure Mode-II loading condition, which provided a bond differential equation that was solved once a certain shape of the interface cohesive material law was assumed. In this paper, a rigid-softening cohesive material law, which considers the possible presence of friction stress contributions at the debonding interface, is adopted to provide the analytical solution of the matrix-fiber interface full-range behavior in FRCM composites. The solution obtained is employed to reproduce the load responses of a PBO FRCM composite subjected to a recently-developed pull-out test and validate the analytical approach
Synergic Authorship: The role of Building Companies in Milanese Modernism, 1930-1960
No full textModern architecture has been characterized by numerous technological innovations that changed not only the architectural lexicon, appearance, and functioning of buildings but also the organization of the design activity and the construction process1. More than in the past, the complexity that architectural design has reached requires collaboration between architects and construction companies, which support the former with technical and professional offices capable of developing their ideas at an executive level. Without denying the fundamental role of the architect/author of masterpieces, it is necessary to broaden the concept of authorship by recognizing the parallel roles and responsibilities.
The case study of the new Montecatini headquarters (hereinafter also referred to as “Montecatini”) in Milan, inaugurated in 1937, and designed by Gio Ponti, Antonio Fornaroli, and Eugenio Soncini, is emblematic in this sense: the architectural design integrates into numerous projects resulting from the research and innovative experimentation of the specialized companies involved. The publication presenting the new Montecatini headquarters represents this complex system of responsibilities and roles well, presenting both the architectural design and those of the individual technological systems developed by the professional technical offices of the companies. This paper focuses on the contribution of company A. Bombelli that, led by well-known authors, designed on an executive level and realized the innovative Anticorodal window system, subsequently patented and presented in publications that recognize the authorship of the company in the development of this technology
Understanding financial networks through minority game
No full textThe recent financial crisis has highlighted the fact that financial systems are complex in nature and understanding financial systems is not a trivial task. One of the major factors that contribute to the complexity of financial systems is the presence of human traders in these systems. Also, the interaction between these human traders leads to traders getting influenced by other trader’ decisions and thus adding another layer of complexity. It has been observed that, social interactions among traders form a social network that influences economic decisions made by these traders. This has lead to a study of a new branch of economics namely “social economics” which takes into consideration the fact that traders are influenced by their social circle. “Social economics” is gaining popularity because the study of psychological aspects of human behavior is able to enhance the modeling of economic models especially the allocation of resources. W.B. Arthur introduced the El Farol Bar Problem in 1994, which shows how agents with bounded rationality and no interaction can show emergent behavior. The Minority game is a variant of the El Farol Bar Problem and it basically shows how agents collectively behave in an ideal situation while competing, by means of adaptation, for a scarce resource even without interacting with each other. In order to extract more characteristics of financial markets from the Minority Game, we modify it by introducing communication among the agents, thereby letting them get influenced by each other’s decisions. We aim to observer herding phenomena as agents are likely to take actions similar to that of their neighbors. Financial markets are quite dynamic in nature and the interacting traders form a network whose topology dynamically evolves. We study the effect on the network topology due to dynamic updates of the link weights of a financial network. We start with two initial network topologies namely a torus network and a random network. We also observe herding phenomenon among the agents. The degree distribution of the nodes of this financial network is fat-tailed, which is characteristic of a network that is robust against random fluctuations.M. S.Includes bibliographical referencesby Savio Jude D'Souz
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