1,324 research outputs found
Ricoprimento sottile periodico di un mezzo elastico soggetto a stress termico residuo
No full textNel presente lavoro viene studiato il problema di contatto e adesione tra uno strato di silicio parzialmente ricoperto da un film sottile di nitruro di silicio, soggetto ad uno stress termico residuo. Questo tipo di microstruttura trova rilevanti applicazioni nel processo di channeling di fasci di particelle ad alta energia. In particolare, si considera un modello periodico con film disposti ad intervalli regolari sia sulla superficie di un semispazio elastico che di uno strato di spessore finito. Utilizzando il metodo delle trasformate integrali, il problema si può formulare attraverso un sistema di equazioni integrali duali. Tale sistema può quindi ricondursi ad un'unica equazione integrale di Fredholm, che può risolversi attraverso tecniche di approssimazione basate sull'impiego dei polinomi di Chebyshev
Insight into seismic behaviour of timber shear-wall systems
No full textThis Ph.D. dissertation is the result of a three-year research activity focused on structural and seismic engineering applied to innovative timber constructive systems. The main purpose is to give a contribution to international scientific research and current design practice about the seismic behaviour of timber shear-wall systems, which still represent an innovation in the construction industry and are being developed due to their favourable characteristics.
An initial overview on the use of main timber structural systems in seismic-prone areas for low- and medium-rise buildings is provided, within the context of current European seismic code.
The theme of the seismic design of timber shear-wall systems is discussed in the first part, giving close attention to linear and non-linear modelling criteria: various strategies are proposed and main characteristics are highlighted. Basic definitions and concepts proper of the seismic analysis of timber structures are provided. A particular attention is paid to the definition and application of the capacity design approach and the close link with the concept of behaviour factor is emphasized. Finally, the definition of behaviour factor, as product between an “intrinsic” capacity of the structure and a design over-strength value is proposed. This definition allows to characterize the structural systems with their proper dissipative capacity and to evaluate separately the safety reserve introduced by design.
The second part analyses the structural behaviour of the cross-laminated timber (CLT) technology, which represents one of the most common timber structural systems. The concepts of ductility, dissipative capacity, regularity and irregularity applied to CLT system are provided. The seismic response and the dissipative capacity of this system are firstly evaluated via an experimentally based procedure. Then, the evaluation of its intrinsic dissipative capacity is determined via non-linear numerical modelling with the aim of studying the correlation with the construction variables. Results show that the construction design decisions affect the seismic response and dissipative capacity of buildings, as opposed to apply a single behaviour factor value to the whole CLT technology. A statistical analysis applied to numerical results allowed also to propose analytical formulations for the computation of the suitable behaviour factor value for regular buildings. Then, the same analyses carried out on in-elevation non-regular buildings returned a correction factor to account for the reduction in dissipative capacity due to irregularity.
The application of the CLT technology to realize high-rise buildings is presented in the third part, analysing the behaviour of slender buildings with seismic resisting core and perimeter shear walls. The major limitations and drawbacks in realizing these structures in areas characterized by high seismic intensity and their implication in the design are reported.
The final part presents three novel structural systems as alternative to more common technologies, as CLT or platform frame. These innovative systems are characterized mainly by a diffuse dissipative and deformation capacity when subjected to seismic loads, while in CLT system such capacity is concentrated in connection elements. This different response is studied via quasi-static tests and numerical simulations. In detail, two non-glued massive timber shear walls and a mixed steel-timber wall with an innovative bracing system are presented
Static and seismic performances of R.C. shear walls cast into wood chip and cement formworks - Experimental tests, theoretical interpretation and numerical validations
No full textThe purpose of this thesis is to study the behavior of the particular building system that makes use of load-bearing walls of reinforced concrete cast into mineralized wood. This construction system has been studied under the action of pseudo-static forces (experimentally and numerically) and under dynamic forces (only numerically). The activities carried out, in general, employed experimental equipment for the realization of tests on materials and on specimens that can be both portions and real scale walls. Additionally, a commercial software has been used for the numerical modeling of the elements composing the construction system in object. In particular, in the first chapters of the thesis, a complete analytical treatment based on experimental results obtained in the years before the Ph.D beginning and during the Ph.D is provided. The original aspects, from the experimental point of view, were the two experimental campaigns concerning portions of panel subjected to direct shear and real scale walls subjected to cyclic horizontal forces in a pseudo-static fashion. In addition, the experimental campaign was completed with the tests on wall-to-wall and wall-to-floor connections required by LL. GG. Min. of Public Works (2011) and aimed at the study of load-bearing walls cast within formwork blocks. The direct shear tests have shown an incongruity of the experimental results with the first analytical treatment developed in the years before 2012 and therefore it was necessary to revise it with new theoretical considerations. A new and original analytical treatment based on strut-and-tie mechanisms was developed. In the last chapters, the construction system has been treated numerically. In the numerical modeling of the structural system the analytical treatment exposed in the first chapters was employed using elements with lumped and distributed plasticity able to simulate the main failure mechanisms documented in the experimental tests. This modeling was first validated on the results of tests on full-scale walls and then used to simulate the behavior of multi-story buildings, regular and irregular, with bi-dimensional and spatial models. These buildings have been subjected to static and dynamic forces typical of seismic action. The numerical results of the simulations coupled with the capacity curves enabled the estimate of the seismic response of the building system and, finally, the behavior factor which best synthesizes it. The estimate of this parameter is of fundamental importance in seismic design, it is one of the main research results. It is worth to notice that the Italian Guidelines prescriptions regarding the behavior factor are more conservative with respect to the results of this researc
Bottom-Up Abstract Modelling of Optical Networks-on-Chip: From Physical to Architectural Layer
No full textThis work presents a bottom-up abstraction procedure based on the design-flow FDTD + SystemC suitable for the modelling of optical Networks-on-Chip. In this procedure, a complex network is decomposed into elementary switching elements whose input-output behavior is described by means of scattering parameters models. The parameters of each elementary block are then determined through 2D-FDTD simulation, and the resulting analytical models are exported within functional blocks in SystemC environment. The inherent modularity and scalability of the S-matrix formalism are preserved inside SystemC, thus allowing the incremental composition and successive characterization of complex topologies typically out of reach for full-vectorial electromagnetic simulators. The consistency of the outlined approach is verified, in the first instance, by performing a SystemC analysis of a four-input, four-output ports switch and making a comparison with the results of 2D-FDTD simulations of the same device. Finally, a further complex network encompassing 160 microrings is investigated, the losses over each routing path are calculated, and the minimum amount of power needed to guarantee an assigned BER is determined. This work is a basic step in the direction of an automatic technology-aware network-level simulation framework capable of assembling complex optical switching fabrics, while at the same time assessing the practical feasibility and effectiveness at the physical/technological level
Correction to: When terminology hinders research: the colloquialisms of transitions of control in automated driving (Cognition, Technology & Work, (2022), 10.1007/s10111-022-00705-3)
No full textIn the original article, author affiliation published with error. The correct affiliations are: Davide Maggi—Institute for Transport Studies, Leeds, UK. Richard Romano—Institute for Transport Studies, Leeds, UK. Oliver Carsten—Institute for Transport Studies, Leeds, UK. Joost C. F. De Winter—Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands. The original article has been corrected.Human-Robot Interactio
Contributions to long-term morphodynamic modelling of estuaries, lagoons, and littoral zones
No full textIn the present thesis I will resume the formulation and some applications of a two-dimensional mathematical model for the long-term representation of the morphodynamic processes which take place in tidal environments. I will refer to non-cohesive sediments, eventually with non uniform grain size.
In the conceptualization presented here the large-scale morphodynamic problem is described based on the concepts of Transport Concentration and Intertidal Dispersion, directly resulting from an appropriate time averaging operation and from an empirical approach to the uncertainties of the problem.
The results of the research activity will be presented in four chapters, each one is meant to enclose completely a conceptual unit of the work performed; these units are preceded by a general outline in which various aspects of the problem are synthesized and contextualised. First the theoretical fundamentals of the model and its multigranular extension will be presented, highlighting the role of the main exogenous forcing factors (tidal range, wind, subsidence and sea level rise) in defining morphology and grain size distribution of tidal environments. Then two applications of the model will be illustrated: the first one studies the impact of different anthropic interventions on a tidal lagoon, the second one aims to quantify the morphodynamic effect of the nodal perturbation of the tidal amplitude.
The thesis is concluded by some considerations on the validity limitations of the model as currently formulated and with some proposals aimed to extending its applicability to complex systems in which the fluvial, estuarine and coastal environment mutually interact at the historical and geological temporal and spatial scales.Nel presente lavoro si espongono la formulazione ed alcune applicazioni di un modello matematico bidimensionale per la rappresentazione a lungo termine dei processi morfodinamici che interessano un ambiente a marea, in presenza di sedimenti non coesivi eventualmente a granulometria non uniforme.
Nella concettualizzazione qui presentata il problema morfodinamico a grande scala spaziale viene descritto sulla base dei concetti di Concentrazione di Trasporto e Dispersione Intermareale, derivanti direttamente da una opportuna operazione di media temporale e da un approccio empirico alla gestione delle incertezze del problema.
I risultati dell'attività di ricerca saranno presentati in quattro capitoli, ciascuno dei quali è inteso a racchiudere compiutamente un nucleo concettuale del lavoro svolto, preceduti da un inquadramento generale in cui i vari aspetti del problema sono sintetizzati e contestualizzati. Dapprima si presenteranno i fondamenti teorici del modello e la sua estensione multigranulare, evidenziando il ruolo delle principali forzanti esogene (ampiezza di marea, vento, subsidenza e innalzamento del livello del mare) nel definire morfologia e granulometria degli ambienti a marea. Quindi si illustreranno due applicazioni del modello: la prima volta a studiare l'impatto esercitato da vari interventi antropici su una laguna a marea, la seconda finalizzata a quantificare l'effetto morfodinamico della perturbazione nodale dell'ampiezza di marea.
La trattazione si conclude con alcune considerazioni sui limiti di validità del modello così come formulato allo stato attuale, e con alcune proposte volte ad estenderne l'applicabilità a sistemi complessi, nei quali gli ambienti fluviale, estuarino e costiero interagiscono mutuamente alle scale spaziali e temporali che sono proprie dei processi storici e geologici
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Biotechnological and Technical Challenges Related to Cultured Meat Production
No full textThe constant growth of the population has pushed researchers to find novel protein sources. A possible solution to this problem has been found in cellular agriculture, specifically in the production of cultured meat. In the following review, the key steps for the production of in vitro meat are identified, as well as the most important challenges. The main biological and technical approaches are taken into account and discussed, such as the choice of animal, animal-free alternatives to fetal bovine serum (FBS), cell biomaterial interactions, and the implementation of scalable and sustainable biofabrication and culturing systems. In the light of the findings, as promising as cultured meat production is, most of the discussed challenges are in an initial stage. Hence, research must overcome these challenges to ensure efficient large-scale production
Starchitecture: Scenes, Actors and Spectacles in Contemporary Cities
No full textHow and why do spectacular buildings get commissioned and procured? What are their visible urban effects? What can urban planners, architects, and policymakers learn in order to engage in more successful citymaking?
In recent years, media and critical attention has been lavished on famous architects, and the contributions of their designs to the branding of cities. The post-“Bilbao effect” global landscape is one where cities compete for the highest-profile skyscrapers, cultural projects, and high-profile developments designed by star architects whom even casual readers know by first name: Frank Gehry, Bjarke Ingels, Jean Nouvel, Zaha Hadid, Norman Foster, Rem Koolhaas. Far less is known about the decision-making processes behind these projects and their subsequent urban effects.
A unique combination of urban studies and photography, Starchitecture investigates projects designed by star architects in cities including Paris, New York, Abu Dhabi, Bilbao, and the architectural microcosm of the Vitra campus in Weil am Rhein, Germany. Author Davide Ponzini and photographer Michele Nastasi seek to explain and critique a growing global condition by revealing how starchitecture has been and continues to be deployed in cities around the world. The arguments they raise are vital to understanding the urban landscapes of today, and tomorrow
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