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Criteri progettuali e sistemi gestionali dell’eco-quartiere. La valenza energetica nella progettazione urbana.
No full textThis research focuses on the ecological neighborhood. It is analyzed not as an independent element but as a related part of the urban system.
The main issue of this research is the interpretation of the planning elements, of the technological solutions and of the managing, economical and social processes which are at the basis of the urban transformation.
Beyond the scale of individual building, the local dimension of the neighborhood is the most suitable for the analysis. It represents the ideal dimension to manage easily the energetic consumption and to foster functional integration strategies related to urban structure. The local dimension also allows to manage the settlement schemes, the collective transportation strategies and the economical and social thematic.
The main aim of this research is the definition of the fundamental elements for the realization (or the transformation) of urban portions characterized by energy efficiency, environmental resource value and by the creation of new urban, social and economical networks. The attention focuses on governance system at the basis of the urban transformation processes, mainly referring to the economic, social and managing themes.
The economic and managing solutions are the “key elements” to determine the success or the inefficacy of the planning strategies.
The first part of the research refers to the theoretical definition of the sustainable urban planning through the study of the historical planning movements and of implemented policies (Smart Growth, New Urbanism, Green Urbanism, Transition Town, European and Italian strategies).
From this theoretical analysis result some criteria for the best practices selection, analyzed in the following section.
The second part of the research deals with the general description of main elements of the ecological neighborhood. It is structured in three main subjects:
- Settlement organization;
- Energy saving technology;
- Managing and economic themes.
The third part of the research deals with the different planning solution for urban transformation. Furthermore it deals with the more precise description of specific intervention instruments and the relations between the local and urban dimension.
Conclusions deals with reflections on the main paths for urban transformation that leads to the creation of new dynamics and urban synergies from the environmental and energetic aspects and the social-economics ones.
The study concentrates on the elements of the whole planning process and the main actors and developers involved to understand what kind of development derived from the urban transformation.
The different planning practices are only about urban retrofitting operations or have became places of new urban synergies and economies at local level
MOBILITY MODELS, MOBILE CODE OFFLOADING, AND P2P NETWORKS OF SMARTPHONES ON THE CLOUD
No full textIt was just a few years ago when I bought my first smartphone. And now, (almost) all of my friends possess at least one of these powerful devices. International Data Corporation (IDC) reports that smartphone sales showed strong growth worldwide in 2011, with 491.4 million units sold – up to 61.3 percent from 2010. Furthermore, IDC predicts that 686 million smartphones will be sold in 2012, 38.4 percent of all handsets shipped. Silently, we are becoming part of a big mobile smartphone network, and it is amazing how the perception of the world is changing thanks to these small devices. If many years ago the birth of Internet enabled the possibility to be online, smartphones nowadays allow to be online all the time. Today we use smartphones to do many of the tasks we used to do on desktops, and many new ones. We browse the Internet, watch videos, upload data on social networks, use online banking, find our way by using GPS and online maps, and communicate in revolutionary ways. Along with these benefits, these fancy and exciting devices brought many challenges to the research area of mobile and distributed systems.
One of the first problems that captured our attention was the study of the network that potentially could be created by interconnecting all the smartphones together. Typically, these devices are able to communicate with each other in short distances by using com- munication technologies such as Bluetooth or WiFi. The network paradigm that rises from this intermittent communication, also known as Pocket Switched Network (PSN) or Opportunistic Network ([10, 11]), is seen as a key technology to provide innovative services to the users without the need of any fixed infrastructure. In PSNs nodes are short range communicating devices carried by humans. Wireless communication links are created and dropped in time, depending on the physical distance of the device holders. From one side, social relations among humans yield recurrent movement patterns that help researchers design and build protocols that efficiently deliver messages to destinations ([12, 13, 14] among others). The complexity of these social relations, from the other side, makes it difficult to build simple mobility models, that in an efficient way, generate large synthetic mobility traces that look real. Traces that would be very valuable in protocol validation and that would replace the limited experimentally gathered data available so far. Traces that would serve as a common benchmark to researchers worldwide on which to validate existing and yet to be designed protocols.
With this in mind we start our study with re-designing SWIM [15], an already exist- ing mobility model shown to generate traces with similar properties of that of existing real ones. We make SWIM able to easily generate large (small)-scale scenarios, starting from known small (large)-scale ones. To the best of our knowledge, this is the first such study. In addition, we study the social aspects of SWIM-generated traces. We show how to SWIM-generate a scenario in which a specific community structure of nodes is required. Finally, exploiting the scaling properties of SWIM, we present the first analysis of the scal- ing capabilities of several forwarding protocols such as Epidemic [16], Delegation [13], Spray&Wait [14], and BUBBLE [12]. The first results of these works appeared in [1], and, at the time of writing, [2] is accepted with minor revision.
Next, we take into account the fact that in PSNs cannot be assumed full cooperation and fairness among nodes. Selfish behavior of individuals has to be considered, since it is an inherent aspect of humans, the device holders (see [17], [18]). We design a market-based mathematical framework that enables heterogeneous mobile users in an opportunistic mobile network to compromise optimally and efficiently on their QoS 3 demands. The goal of the framework is to satisfy each user with its achieved (lesser) QoS, and at the same time maximize the social welfare of users in the network. We base our study on the consideration that, in practice, users are generally tolerant on accepting lesser QoS guarantees than what they demand, with the degree of tolerance varying from user to user. This study is described in details in Chapter 2 of this dissertation, and is included in [3].
In general, QoS could be parameters such as response time, number of computations per unit time, allocated bandwidth, etc.
Along the way toward our study of the smartphone-world, there was the big advent of mobile cloud computing—smartphones getting help from cloud-enabled services. Many researchers started believing that the cloud could help solving a crucial problem regarding smartphones: improve battery life. New generation apps are becoming very complex — gaming, navigation, video editing, augmented reality, speech recognition, etc., — which require considerable amount of power and energy, and as a result, smartphones suffer short battery lifetime. Unfortunately, as a consequence, mobile users have to continually upgrade their hardware to keep pace with increasing performance requirements but still experience battery problems. Many recent works have focused on building frameworks that enable mobile computation offloading to software clones of smartphones on the cloud (see [19, 20] among others), as well as to backup systems for data and applications stored in our devices [21, 22, 23]. However, none of these address dynamic and scalability features of execution on the cloud. These are very important problems, since users may request different computational power or backup space based on their workload and deadline for tasks.
Considering this and advancing on previous works, we design, build, and implement the ThinkAir framework, which focuses on the elasticity and scalability of the server side and enhances the power of mobile cloud computing by parallelizing method execution using multiple Virtual Machine (VM) images. We evaluate the system using a range of benchmarks starting from simple micro-benchmarks to more complex applications. First, we show that the execution time and energy consumption decrease two orders of magnitude for the N-queens puzzle and one order of magnitude for a face detection and a virus scan application, using cloud offloading. We then show that a parallelizable application can invoke multiple VMs to execute in the cloud in a seamless and on-demand manner such as to achieve greater reduction on execution time and energy consumption. Finally, we use a memory-hungry image combiner tool to demonstrate that applications can dynamically request VMs with more computational power in order to meet their computational requirements. The details of the ThinkAir framework and its evaluation are described in Chapter 4, and are included in [6, 5].
Later on, we push the smartphone-cloud paradigm to a further level: We develop Clone2Clone (C2C), a distributed platform for cloud clones of smartphones. Along the way toward C2C, we study the performance of device-clones hosted in various virtualization environments in both private (local servers) and public (Amazon EC2) clouds. We build the first Amazon Customized Image (AMI) for Android-OS—a key tool to get reliable performance measures of mobile cloud systems—and show how it boosts up performance of Android images on the Amazon cloud service. We then design, build, and implement Clone2Clone, which associates a software clone on the cloud to every smartphone and in- terconnects the clones in a p2p fashion exploiting the networking service within the cloud. On top of C2C we build CloneDoc, a secure real-time collaboration system for smartphone users. We measure the performance of CloneDoc on a testbed of 16 Android smartphones and clones hosted on both private and public cloud services and show that C2C makes it possible to implement distributed execution of advanced p2p services in a network of mobile smartphones. The design and implementation of the Clone2Clone platform is included in [7], recently submitted to an international conference.
We believe that Clone2Clone not only enables the execution of p2p applications in a network of smartphones, but it can also serve as a tool to solve critical security problems. In particular, we consider the problem of computing an efficient patching strategy to stop worm spreading between smartphones. We assume that the worm infects the devices and spreads by using bluetooth connections, emails, or any other form of communication used by the smartphones. The C2C network is used to compute the best strategy to patch the smartphones in such a way that the number of devices to patch is low (to reduce the load on the cellular infrastructure) and that the worm is stopped quickly. We consider two well defined worms, one spreading between the devices and one attacking the cloud before moving to the real smartphones. We describe CloudShield [8], a suite of protocols running on the peer-to-peer network of clones; and show by experiments with two different datasets (Facebook and LiveJournal) that CloudShield outperforms state-of-the-art worm-containment mechanisms for mobile wireless networks. This work is done in collaboration with Marco Valerio Barbera, PhD colleague in the same department, who contributed mainly in the implementation and testing of the malware spreading and patching strategies on the different datasets.
The communication between the real devices and the cloud, necessary for mobile com- putation offloading and smartphone data backup, does certainly not come for free. To the best of our knowledge, none of the works related to mobile cloud computing explicitly studies the actual overhead in terms of bandwidth and energy to achieve full backup of both data/applications of a smartphone, as well as to keep, on the cloud, up-to-date clones of smartphones for mobile computation offload purposes. In the last work during my PhD—again, in collaboration with Marco Valerio Barbera—we studied the feasibility of both mobile computation offloading and mobile software/data backup in real-life scenarios. This joint work resulted in a recent publication [9] but is not included in this thesis. As in C2C, we assume an architecture where each real device is associated to a software clone on the cloud. We define two types of clones: The off-clone, whose purpose is to support computation offloading, and the back-clone, which comes to use when a restore of user’s data and apps is needed. We measure the bandwidth and energy consumption incurred in the real device as a result of the synchronization with the off-clone or the back-clone. The evaluation is performed through an experiment with 11 Android smartphones and an equal number of clones running on Amazon EC2. We study the data communication overhead that is necessary to achieve different levels of synchronization (once every 5min, 30min, 1h, etc.) between devices and clones in both the off-clone and back-clone case, and report on the costs in terms of energy incurred by each of these synchronization frequencies as well as by the respective communication overhead. My contribution in this work is focused mainly on the experimental setup, deployment, and data collection
Il rapporto fra l’architettura moderna e contemporanea nella trasformazione della preesistenza nell’architettura di Roma dal 1945 ai giorni nostri. I quartieri Esquilino, Castro Pretorio, Sallustiano e Ludovisi - Lettura a scala urbana e architettonica.
No full textIl rapporto tra i nuovi interventi e la preesistenza dell’area di Roma compresa tra i rioni Esquilino, Castro Pretorio, Sallustiano e Ludovisi, nel secondo dopoguerra è il risultato di scelte e di approcci all’architettura e all’area urbana esistente, che hanno cambiato non solo l’immagine della città in quell’area, ma anche l’approccio contemporaneo all’architettura del passato e alle aree storiche consolidate. Le dinamiche che hanno condotto al nuovo assetto urbano dell’area di studio sono state analizzate attraverso la ricerca della documentazione bibliografica e in particolar modo di quella esistente nelle riviste di architettura di quegli anni, deducendo più gli aspetti inerenti l’approccio al luogo e alle preesistenze architettoniche anche demolite e perdute, piuttosto che gli aspetti architettonici e progettuali dei singoli esempi, spesso decontestualizzati.
La tematica, affronta inizialmente uno studio sull’area e sugli sviluppi dei rioni romani a Nord-Est della città cercando di riconoscere le stratificazioni storiche, gli sviluppi urbani e le presenze architettoniche con le quali i nuovi interventi hanno dovuto confrontarsi a partire dal 1945. Il confronto non si limita a comprendere solo gli aspetti più visibili dell’architettura costruita, ma cerca di indagare le scelte e le proposte per poi giungere alla definizione dei risultati concreti della realizzazione dei nuovi edifici oggetto di interesse. La documentazione, l’analisi delle planimetrie delle aree di studio e la rilettura dei bandi di concorso, hanno consentito di comprendere quanto la realtà preesistente abbia influito o meno sulle scelte progettuali finali.
La Testata della Stazione Termini fu il risultato di un bando di concorso risalente al 1947, che definiva sin dal principio il rispetto delle presenze storiche; l’aggere Serviano divenne un punto di riferimento per definire il dimensionamento della pensilina del fronte principale e la sua distribuzione planimetrica; le ali già realizzate con il progetto di Mazzoni costituirono un limite in pianta e in alzato su via Giolitti e via Marsala; il rapporto con la piazza antistante e con le antiche Terme di Diocleziano rappresentò una tematica urbana ancora oggi molto discussa.
“La Rinascente” a Piazza Fiume e l’edificio di via Campania si rapportavano alla preesistenza delle antiche Mura Aureliane e all’intero quartiere attraverso un approccio compositivo innovativo rispetto al passato, anche in funzione del cambiamento socio-culturale e tecnologico di quegli anni. La Rinascente fu progettata impiegando una composizione di ‘rigorosa radice tecnologica’ con il muro di tamponamento senza finestrature, con un volume predefinito e una struttura metallica a vista sulle facciate. In questo intervento viene interpretato un duplice rapporto con il passato: il primo, riprendendo un colloquio interrotto a distanza di secoli tra l’ambiente romano e quello lombardo; il secondo, rapportando l’edificio ad una piazza sulla quale, di fronte, sono presenti le antiche Mura Aureliane.
Il complesso di via Campania ricerca radici profonde nella romanità del passato mentre la sua modernità è attribuita al fatto che esso rappresenta un lavoro di ‘tipo metalinguistico’ capace di superare il problema stilistico adottando tre diversi linguaggi associati a tre diverse funzioni riscontrabili ai vari piani; il dialogo con la preesistenza e l’ambientamento nel contesto è risolto non attraverso una mimesi ma attraverso la ricezione del riflesso delle mura Aureliane sul vetro bruno della facciata.
Un decreto del Presidente della Repubblica apportò modifiche al P.R.G. per realizzare l’Ambasciata Britannica, che venne costruita su un’area destinata inizialmente a parco privato. Su questa area sorgeva il Palazzo Torlonia, già sede dell’ambasciata Britannica dal 1870, distrutto da un attentato nel 1949. Nel 1960, il governo inglese decise di ricostruire la nuova sede nello stesso luogo, affidando l’incarico all’architetto britannico Sir Basil Spence. Il nuovo progetto nello schema a pianta centrale traeva spunto dal codice manieristico cercando un riferimento con la vicina Porta Pia che in verità fu negato dall’arretramento dell’ingresso rispetto al contesto michelangiolesco.
La Biblioteca Nazionale Centrale al Castro Pretorio, fu realizzata anch’essa attraverso un bando di concorso nazionale del 1959, che non prevedeva solo il progetto architettonico della biblioteca, ma anche di avanzare idee e proposte per la sistemazione dell’intera zona. Il complesso si confrontava con la realtà delle poche costruzioni militari, delle quali fu prevista la demolizione, e le mura Aureliane. Il progetto vincitore non interpretò più la biblioteca secondo un concetto ottocentesco ma riuscì a coniugare la modernità dei meccanismi di automatizzazione con bassi costi di gestione.
L’architettura moderna di questi anni fu messa a dura prova nell’incontro tra la città antica e l’edilizia nuova. Si aprirono accesi dibattiti attraverso le riviste specializzate e nei convegni organizzati per affrontare la tematica del rapporto tra ‘antico e nuovo’. Si cercò di comprendere il valore del punto di incontro tra la cultura contemporanea e il passato non cercando una negazione o una frattura ma un dialogo tra i diversi momenti creativi. R. Pane affermava che “il patrimonio d’arte e di storia non si pone come una intimidazione a danno della moderna creatività, ma esige invece di essere integrato in una autentica creatività, dato che esso non è una parte morta della città ma la sua parte più viva e coerente”. E ancora, per citare B. Zevi, “gli architetti moderni potranno attuare un positivo incontro tra antico e nuovo solo quando conosceranno a fondo l’antico e avranno il coraggio di inventare, di pensare di nuovo”
TEMPLI SENZA ALTARE, THESAUROI E OIKOI. UN’INDAGINE SUGLI ASPETTI ECONOMICI DEL SANTUARIO GRECO
No full textThe research analyzes economic aspects of the Greek sanctuary, paying special attention to the relation between temenos and polis in the management of public finance during the Arcaic and Classical period.
Greek sanctuaries were in fact marked by a relevant economic dimension. In this respect, golden and silver chremata kept inside them did not only mean to be sacred properties belonging the deity, to be used to build sanctuaries’ edifices and to perform ritual practices, but were actually intended as a public financial fund the polis could use for civic purposes in case of need. The work mainly exams archaeological, literary and epigraphic documentation concerning the Athenian Acropolis, the Heraion of Samos, the Heraion and Athenaion of Argos
La neutralità ai fini delle imposte sui redditi delle operazioni straordinarie che implicano la circolazione di compendi aziendali. Un’analisi ragionata fra applicazioni di sistema ed agevolative.
No full textHIGH RESOLUTION RADARGRAMMETRY WITH COSMO-SKYMED, TERRASAR-X AND RADARSAT-2 IMAGERY: DEVELOPMENT AND IMPLEMENTATIONOF AN IMAGE ORIENTATION MODEL FOR DIGITAL SURFACE MODEL GENERATION
No full textDigital Surface and Terrain Models (DSM/DTM) have large relevance in several territorial applications, such as topographic mapping, monitoring engineering, geology, security, land planning and management of Earth's resources. The satellite remote sensing data offer the opportunity to have continuous observation of Earth's surface for territorial application, with short acquisition and revisit times. Meeting these requirements, the SAR (Synthetic Aperture Radar) high resolution satellite imagery could offer night-and-day and all-weather functionality (clouds, haze and rain penetration). Two different methods may be used in order to generate DSMs from SAR data: the interferometric and the radargrammetric approaches. The radargrammetry uses only the intensity information of the SAR images and reconstructs the 3D information starting from a couple of images similarly to photogrammetry. Radargrammetric DSM extraction procedure consists of two basic steps: the stereo pair orientation and the image matching for the automatic detection of homologous points.
The goal of this work is the definition and the implementation of a geometric model in order to orientate SAR imagery in zero Doppler geometry.
The radargrammetric model implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione - developed at the Geodesy and Geomatic Division - University of Rome "La Sapienza") is based on the equation of radar target acquisition and zero Doppler focalization
Moreover a tool for the SAR Rational Polynomial Coefficients (RPCs) generation has been implemented in SISAR software, similarly to the one already developed for the optical sensors. The possibility to generate SAR RPCs starting from a radargrammetric model sounds of particular interest since, at present, the most part of SAR imagery is not supplied with RPCs, although the RPFs model is available in several commercial software. Only RADARSAT-2 data are supplied with vendors RPCs.
To test the effectiveness of the implemented RPCs generation tool and the SISAR radargrammetric orientation model the reference results were computed: the stereo pairs were orientated with the two model.
The tests were carried out on several test site using COSMO-SkyMed, TerraSAR-X and RADARSAT-2 data.
Moreover, to evaluate the advantages and the different accuracy between the orientation models computed without GCPs and the orientation model with GCPs a Monte Carlo test was computed.
At last, to define the real effectiveness of radargrammetric technique for DSM extraction and to compare the radrgrammetric tool implemented in a commercial software PCI-Geomatica v. 2012 and SISAR software, the images acquired on Beauport test site were used for DSM extraction. It is important underline that several test were computed. Part of this tests were carried out under the supervision of Prof. Thierry Toutin at CCRS (Canada Centre of Remote Sensing) where the PCI-Geomatica orientation model was developed, in order to check the better parameters solution to extract radargrammetric DSMs.
In conclusion, the results obtained are representative of the geometric potentialities of SAR stereo pairs as regards 3D surface reconstruction
Hystorical Rules and Theories on Masonry Arches from the Renaissance to Monasterio and Persy
No full textCammino storico evolutivo sulle teorie degli archi in muratura a partire dal Rinascimento fino ai primi anni del 1800.
La costruzione di questo cammino è iniziata con la rivisitazione, mediante lettura esegetica e critica, delle regole costruttive utilizzate nel Rinascimento, delle teorie pre-elastiche di La Hire, Coulomb e Mascheroni del XVIII° secolo ed infine della teoria sugli archi non simmetrici descritta da Monasterio nel suo trattato inedito, Nueva Teorica sobre el empuje de bovedas, dell’inizio del XIX° secolo e della teoria per l’individuazione dei meccanismi di collasso degli archi simmetrici di Nicolas Persy descritta nella sua raccolta di lezioni, Cours sur la stabilité des constructions, à l’usage des élèves de l’ école royale de l’Artillerie et du Génie, Stabilité des voûtes del 1825.
Nell’analisi di queste teorie, per le strutture ad arco o voltate, in blocchi lapidei o muratura, è stato adottato il modello di corpo rigido soggetto a vincoli unilaterali ed attrito, per tenere in debito conto la scarsa resistenza a trazione del materiale e la elevata resistenza a compressione.
Il modello meccanico dell’arco murario come struttura mono-dimensionale governata ai giunti da opportune leggi di contatto normale e tangenziale.
La cinematica, la statica e la cinetica del sistema possono così essere definite, permettendo di individuare in condizioni di equilibrio stabile i range delle reazioni staticamente ammissibili come funzione della spinta in chiave.
La filosofia che soggiace ad un tale approccio per l’analisi delle strutture voltate lapidee o murarie consente di riabilitare la validità delle teorie pre-elastiche sulle strutture voltate lapidee o murarie
Intensity Measures for Seismic Response Prediction and associated Ground Motion Selection and Modification
No full textBased on the research of the first generation of Performance-Based Earthquake engineering methodology (PBEE), Pacific Earthquake Engineering Research Centre (PEER) has developed the second generation procedure aiming at a more robust methodology of PBEE where the process is broken into several logical elements that can be studied and resolved in a rigorous and consistent manner. Due to the inherent uncertainty properties of earthquake occurrence, e.g. earthquake intensity, ground motion features, nonlinear dynamic behaviour of structures and etc., it allows that the new generation of PBEE methodology should be formalized within a probabilistic basis. To apply this methodology it requires an interactive effort of multi-disciplinary experts, such as geology engineers, seismologist, structural engineers, loss experts and etc. For structural engineers the most interest can be relevant to the selection and estimation of two parameters in PBEE, i.e. Intensity Measures (IM) and Engineering Demand Parameters (EDP), which reflect ground motion hazard and structural response in terms of deformations, accelerations, or other response quantities of the building excited by input ground motions.
The EDPs are strongly dependent on the Intensity Measure (IM) used to perform the selection of ground motions. The IM as an intermediate variable connecting seismic analysis and structural analysis plays a very important role for structural engineers. An ideal IM should generally be of efficiency and sufficiency. The efficiency means it yields low dispersion of values of engineering demand parameter (EDP), while the sufficiency implies that EDP predicted with the candidate IM should be only dependent on this IM, not be conditionally dependent on properties of ground motions, like magnitude, source to site distance, fault mechanism etc. Therefore it implies the need of comparison among different intensity measures (IMs), in particular the comparison of dispersion of the EDP in relation to each IM. To this purpose a set of IMs 27 IMs, including those commonly adopted and some modified IMs based on the existed ones, are investigated in order to find optimum IMs for predicting various EDPs. Not only is IMs for predicting the structural response of widely studied fixed base buildings are investigated, but also IMs for predicting structural response of the base-isolated buildings are initiatively studied. 80 ordinary and 59 pulse-like ground motion records are used to run nonlinear dynamic analyses on the 4-storey and 6-storey frame concrete buildings and these buildings equipped with base-isolation system on them. The EDPs considered in this study include the Maximum Inter-storey Drift Ratio (MIDR), the Maximum Roof Drift Ratio (MRDR) and the Maximum Base Displacement (MBD, only for base-isolated buildings).
Base on the results from this study some energy-based intensity measures have been shown to be good predictors of both structural and non-structural damage for base-isolated structures. However, they are not usually employed in probabilistic seismic demand analyses because of the lack of reliable Ground Motion Prediction Equations (GMPEs). In order to define seismic hazard and thus to calculate demand hazard curves it is essential, in fact, to establish a GMPE for the earthquake intensity. In the light of this need, new GMPEs are proposed here for the energy-based intensity measure, in particular elastic input energy equivalent velocity spectra i.e. VEIa and VEIr. The new GMPE is developed by taking advantage of the more comprehensive NGA database with more completed meta-data compiled in recent years. This prediction equation has a wider magnitude and distance applicable range, considers the effect of soil site by VS30 and fault mechanism, and etc.
However when the energy-based IMs are used in the selection and modification of ground motions for structural dynamic analyses, the uniform hazard spectrum derived from their GMPEs only gives the marginal distribution without information of joint occurrence of spectral values at different periods. In fact the uniform hazard spectrum of spectral acceleration is widely demonstrated to cause conservative results. Therefore the correlation of the elastic input energy spectral values at different periods is initiatively evaluated and the analytical predictive equation is also proposed to calculate the correlation of elastic input energy spectral values. Using the correlation their conditional mean spectrum recognized as a more appropriate target spectrum for ground motions selections can be developed. On the other hand this correlation also can be used to calculate the predicted mean value and the dispersion of some integral intensity measures (such as VEIaSI, VEIrSI, MVEIaSI, MVEIrSI), achieving the application of these IMs in Performance-Based Earthquake Engineering.
Finally, we made a practical Matlab implementation for ground motion selection and modification. Here it is called RELACS (REaL ACcelerogram Selection). The total ground motion database used in RELACS, with more available ground motion records, is composed of three large ground motion database, i.e. NGA (Next Generation Attenuation) database, SISMA (Site of Italian Strong Motion Accelerograms) database, and ESGM (European Strong Ground Motion) Database. The RELACS brings to engineers and researchers more convenience to select ground motion accelerograms, using nowadays widely adopted GMSM methods in terms of not only some commonly used acceleration-based IMs and some other scalar intensity measures but also some energy-based IMs that have been approved good predictors for the response of base-isolated buildings. The RELACS contains two consecutive steps: selection according to the geophysical parameters; and selection according to the elastic response parameters (IMs). The user can easily obtain the acceleration time-history, and the acceleration spectrum, the velocity spectrum and the displacement spectrum of the ground motion record selected using the RELACS
Crystal-chemistry of "bioapatite" deposits from valve tissues of the human heart: from macrostructures to nanocrystals
No full textBiomineralization is well-known as the essential process for human skeletal development. It is a complex and multistage process requiring an interaction of many physicochemical factors. It results in highly complex mineral-organic products in which organic and inorganic components are structured on many dimensional scales to form hierarchical architectures.
From a mineralogical point of view the concept of biomineral refers not only to mineral produced with the intervention of living organisms but to phases characterized by specific features and properties that distinguish them from their bulk, macroscopic counterparts formed geologically or synthetically. Calcium phosphate phases can be considered the most important class of biominerals. These take place in human body mainly as physiologic products such as bones and teeth but also as pathological products, when their formation occurs outside the normal mineralization sites.
In different scientific fields these are generically known with the inappropriate term of calcifications to distinguish them from the products having a precise function in the human body; from a mineralogical point of view this well-defined distinction is not taken to account and all biominerals meet only the criteria for being true minerals.
The present thesis addresses the issue of “pathological” calcium phosphate biominerals within valve tissues of the human heart. Nowadays the formation of such biominerals is a worldwide important topic associated with major morbidity, mortality and health economic costs. These represent the leading cause of failure of natural and bioprosthetic heart valves and the major indication for surgical valve replacement. The mechanisms involved in their deposition are still poorly understood and no medical intervention is able to delay or halt “calcification” progression, thus there is a pressing need to deeply understanding the biomineralization processes linked to these “pathological” calcium phosphate phases.
Aim of the present thesis is to provide a comprehensive mineralogical characterization of such calcium phosphate biominerals in an effort to obtain new insights into the factors controlling this biomineralization process and hence to supply a better picture on which to base new hypothesis on the nucleation and growth processes linked to these phases.
Composition, morphology, crystallite size and structure are all correlated with their growth conditions; an understanding of their morphological and crystal-chemical features allows to gain valuable information on their crystallization pathways.
The main debated issues linked to calcium phosphate biominerals will be discussed, starting from a clarification of the term “bioapatite” used in this study to indicate a well-distinct calcium phosphate phase but often used improperly in different scientific fields. Relevant topics concerning specific features of the nanocrystalline bioapatite will be developed. These include: 1) location of the carbonate group CO32- in the bioapatite lattice; 2) carbonate content; 3) hydroxylation degree; 3) bioapatite stoichiometry 4) surface properties; 5) presence of precursor phases; 6) macro- and microstructures; 7) nanocrystals structure.
Complementary mineralogical techniques were employed to obtain a comprehensive characterization of this biomineral phase, and a multi-scale investigation, from millimeters to nanometers, has been conducted to define all structural organization levels, typical of biomineral phases. The greatest difficulties linked to the characterization of natural nanocrystalline bioapatites will be also discussed.
The complete mineralogical characterization has allowed to determine the lowest units constituting the “pathological” deposits within the valve tissues of the human heart. These are represented by needle- and rod-like nanocrystals showing characteristic aggregation properties in a wide range of crystallite size associated to local growth conditions and to different mineralization sites.
The nucleation and growth mechanisms of the investigated phase seem to be mainly regulated by thermodynamic and physicochemical factors while the role of the organic matrix appears to be mainly limited to a spatial template; both homogeneous and heterogeneous nucleation processes appear to be involved in the formation of “pathological” nanocrystals, and in the latter case a surface-induce mineralization process linked to the functionalization of the organic interfaces by negatively charged functional groups can be hypothesized.
The presence of the CO32- group both in the bioapatite lattice and as labile ions localized at the nanocrystals surface, as well as the presence of the HPO42- group, suggests a possible involvement of these functional groups in inducing bioapatite nucleation onto organic substrate and a superficial ionic mobility. This can assume an important role for the chemical interactions of the inorganic phase with the organic matrix and the biological fluids representing a relevant feature for ion exchange processes.
Finally, at larger length scales, the three-dimensional arrangement of bioapatite nanocrystals in spherulitic shapes located onto and beside the collagen fibrils, or in the form of uniform mineral coating, seems to be linked to the local density and distribution of the organic network, but also to aggregation processes ruled by surface energy minimization
Switching type valuation and design problems in general OTC contracts with CVA, collateral and funding issue.
No full textIn this work, we think to a possible real situation where two defaultable counterparties want to
de fine a CSA in which both of them need the
flexibility and the possibility to activate the collateralization
during the life of the underlying claim/contract. We refer speci cally to a contingent
risk mitigation mechanism that allows the counterparty to switch from zero to full/perfect collateralization
(or even partial) and switch back whenever she wants until maturity paying some
switching costs and taking into account the running costs that emerge over time.
The running costs that we model and consider in the analysis of this problem are - by one side -
those related to CVA namely counterparty risk hedging costs and - by the other side - the collateral
and funding/liquidity costs that emerge when collateralization is active. We show the solution existence and uniqueness for the problem so defined, we build also an algorithm to determine numerically the value function and the optimal switching strategy. We also generalize the analysis allowing the strategic interaction between the parties and facing in the end the pricing problem of a general contract of this kind through reflected backward SDE technique