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Corrective Evolution of Adaptable Process Models
No full textModeling business processes is a complex and time-consuming task, which can be simplified by allowing process instances to be structurally adapted at runtime, based on context (e.g., by adding or deleting activities). The process model then no longer needs to include a handling procedure for every exception that can occur. Instead, it only needs to include the assumptions under which a successful execution is guaranteed. If a design-time assumption is violated, the exception handling procedure matching the context is selected at runtime. However, if runtime structural adaptation is allowed, the process model may later need to be updated based on the logs of adapted process instances. Evolving the process model is necessary if adapting at run-time is too costly, or if certain adaptations fail and should be avoided. An issue that is insufficiently addressed in the previous work on process evolution is how to evolve a process model and also ensure that the evolved process model continues to achieve the goal of the original model. We refer to the problem of evolving a process model based on selected instance adaptations, such that the evolved model satisfies the goal of the original model, as corrective evolution. Automated techniques for solving the corrective evolution problem are necessary for two reasons. First, the more complex a process model is, the more difficult it is to be changed manually. Second, there is a need to verify that the evolved model satisfies the original goal. To develop automated techniques, we first formalize the problem of corrective evolution. Since we use a graph-based representation of processes, a key element in our formal model is the notion of trace. When plugging an instance adaptation at a particular point in the process model, there can be multiple paths in the model for reaching this point. Each of these paths is uniquely identified by a trace, i.e., a recording of the activities executed up to that point. Depending on traces, an instance adaptation can be used to correct the process model in three different ways. A correction is strict if the adaptation should be plugged in on a precise trace, relaxed if on all traces, and relaxed with conditions if on a subset of all traces. The choice is driven by competing concerns: the evolved model should not introduce untested behavior, but it should also remain understandable.
Using our formal model, we develop automated techniques for solving the corrective evolution problem in two cases. The first case is also the most restrictive, when all corrections are strict. This case does not require verification, since the process model and adaptations are assumed to satisfy the goal, as long as the adaptations are applied on the corresponding traces. The second case is when corrections are either strict or relaxed. This second case requires verification, and for this reason we develop an automated technique based on planning. We implemented the two automated techniques as tools, which are integrated into a common toolkit. We used this toolkit to evaluate the tradeoffs between applying strict and relaxed corrections on a scenario built on a real event log
Esperienza e rivolta: implicazioni storico-filosofiche dell'esperienza dell'assurdo e della Resistenza in Albert Camus (1939-1947)
No full textLa presente ricerca si concentra sull’idea di ‘rivolta’ attraverso un’indagine specifica sulle opere concepite e pubblicate da Albert Camus tra il 1939 e il 1947 (Noces, Le Mythe de Sisyphe, Lettres à un ami allemand, Remarque sur la révolte, La Peste, gli articoli di «Combat»). La datazione indicata nel titolo si riferisce, infatti, a una precisa delimitazione della ricerca storico-filosofica a un arco di tempo determinato, la cerniera temporale costituita da due date fondamentali: il 1939, che segna l’inizio del secondo conflitto mondiale, e il 1947, l’anno dell’uscita di Camus dalla redazione di «Combat» e della pubblicazione de La Peste, romanzo che rielabora in forma allegorica l’Occupazione e la Resistenza. La svolta di senso data da Camus all’idea di ‘rivolta’ nella Remarque sur la révolte, negli anni che vanno dal 1943 al 1945, è il frutto, in primo luogo, di un confronto serrato con il nichilismo descritto e ‘appoggiato’ ne Le Mythe de Sisyphe; in secondo luogo, dello sforzo di comprensione delle congiunture storico-culturali del proprio tempo, delle implicazioni morali dell’evento della Seconda Guerra Mondiale, delle idee che circolavano nella stampa clandestina e resistente, del pensiero della Resistenza in generale. L’evoluzione della nozione di rivolta è tracciata attraverso un costante confronto con il contesto politico-culturale del tempo: prima nell’esperienza individuale dell’assurdo; poi nel vissuto collettivo della Resistenza francese all’Occupazione
Cholesterol-Dependent Cytolysins and Perforin: Similar Pore-Forming Mechanisms in Pathogenic Attack and Human Immune Defense
No full textMACPF/CDCs proteins are a huge family of pore-forming proteins present from the bacteria to the human genera. Cholesterol-dependent cytolysins (CDCs) are a family of toxins that participate in bacterial infection pathway at the membrane level. Great interest in this family is due to their similarity, in structure and in pore-forming mechanism, with some human immune system proteins (MACPF). We focused our attention particularly on two bacterial CDCs, Perfringolysin O and Listeriolysin O, and on the human protein Perforin, which is involved in the apoptotic pathway facilitating Granzyme release. In the literature, two possible configurations of CDCs and Perforin pores are proposed: ring and arc structures that could have different implications on the biological mechanism of action of these pore-forming proteins. By electrophysiological measurements and atomic force microscopy technique on different artificial membrane, we are able to enrich the ring and the arc fraction and demonstrate that both kinds of pore are active, i.e. conduct ions.
Thus, my PhD work underlines two physiological structures which are involved in several ways, more than merely by disrupting membrane integrity, in pathogenic attack (bacterial CDCs proteins) as well as in immune response (human Perforin proteins)
Morphodynamics and driftwood dispersal in braided rivers
No full textDriftwood is widely recognized as a relevant component of riverine systems due to its complex interactions with flow, sediment transport and vegetation dynamics. In-channel large wood has a relevant geomorphic and ecological role as it enhances morphological diversity and creates a variety of physical habitats that sustain high biodiversity. Its presence can also increase flood risk and therefore wood is often removed from streams especially in densely populated areas. Recent river restoration policies aim to maximise the environmental benefits of driftwood and minimise risks. The study of wood dynamics can provide useful information to define guidelines for sustainable wood management.
Multi-thread systems represent a particularly interesting and challenging context for the investigation of wood dynamics because of their complex geometry, the presence of vegetated islands and the frequent, intense changes in channel pattern observed even for moderate discharge fluctuations. However, comparatively few studies focus on driftwood in large braided rivers and limited quantitative information is available on wood transport, deposition and remobilisation in these systems. The goals of the present work are: a) characterising the spatial organisation of wood deposits and identifying typical retention sites and styles; b) analysing the influence of flow regime, channel morphology, wood supply and log properties (size and shape) on dispersal patterns; c) investigating wood remobilisation induced by discharge fluctuations and bed reworking; and d) analysing long-term wood storage volume and budget.
A combination of field-scale direct observations, remote sensing techniques and physical modelling was used to investigate wood and channel dynamics. Field-scale monitoring carried out on the Tagliamento River (Italy) allowed the observation of complex interactions and feedbacks between channel, vegetation and wood dynamics. Laboratory simulations – carried out in two large flumes at the University of Trento (Italy) and at the University of Hull (UK) – were employed to investigate individual wood dispersal mechanisms under controlled conditions and to explore the role of governing parameters.
In large rivers, floods are the primary driver of wood recruitment through the erosion of vegetated banks and islands; field-scale observations showed that these localised wood inputs control wood storage at sub-reach scale because a large proportion of eroded trees is retained close to the input point in sparse, small jams. Physical modelling highlighted a complex relationships between flow stage and the longitudinal and vertical distribution of wood; high discharge increases the ability of the system to transfer wood, but at the same time generates complex inundation patterns where a larger number of sites are available for wood retention. No clear link between flow stage and the vertical distribution of wood is observed, probably because water surface elevation exhibits small changes with discharge in flat braided river cross-sections. Driftwood element properties also influence deposition patterns; log diameter controls travel distance as it governs flotation and therefore the likeliness of deposition. High element length and complex piece shape sustain the formation of large jams. The presence of a root bole is also associated to short travel distance and low relative elevation.
At reach-scale, the spatial distribution of wood is the product of local inputs during major floods and reorganisation of deposits induced by minor events. Wood pattern exhibits a threshold behaviour with supply. High input rates determine very high spatial density and the formation of large, stable jams. Two processes govern wood reorganisation over different time scales, namely network inundation – inducing rapid changes in flow field – and bed reworking. In the first case, the persistence of deposits depends on the magnitude of discharge fluctuations as wood dispersed by small floods is easily removed by larger events. High relative elevation and large jam size enhance wood stability, while the presence of a root wad has a dual effect as it determines large accumulations at low elevation. Channel pattern reworking determines intense turnover of driftwood deposits regardless of supply rate, piece properties and jam size, save for very large accumulations. As a consequence, wood deposition occurs mostly on empty braidplain areas as opposed to pre-existing sites.
These results suggests that wood (alone) has little direct effect on reach-scale bed geometry in a large braided river; however, deposited wood significantly influences local hydraulics and morphology, enhancing physical habitat diversity. Moreover, deposited wood favours the accumulation of fine sediment, nutrients and seeds and often exhibits vegetative regeneration. These processes lead to the transformation of instable driftwood pieces into vegetated islands, which in turn can trap more wood. Therefore, wood has a relevant, indirect effect on braided river morphodynamics through the establishment of vegetation, whose presence influences network complexity and evolution
L'Ottimo Commento alla "Commedia". "Paradiso". Saggio di edizione critica
No full textEdizione critica dell'Ottimo Commento al Paradiso dantesco
The Neural Basis of Action Understanding
No full textIn daily life, we constantly observe actions of other people and try to attribute a meaning to these actions. This ability is fundamental to our survivor. Despite intense research, the neural basis of action understanding is still poorly understood. The aim of the present thesis is to investigate the neural networks involved in the process of action understanding in humans using functional
magnetic resonance and diffusion tensor imaging (fMRI and DTI)
Hydrological modelling with components: the OMS3 NewAge-JGrass system
No full textNewAge-JGrass system for forecasting and modelling of water resources in general at the basin scale. As a modern hydrological modelling, it is composed of two parts: (i) the system for data and results visualization based on the Geographic Information System uDig and (ii) the component based modelling system.
All the system is based on Java because of its portability. Java is a modern and mature language aware of the web and has features such as multithreading that are essential to build scalable modelling platform. There are a few open source frameworks available that allow adaptation for our task, such as the GeoTools project by the Open GIS Consortium, representing a solid foundation for spatial analysis.
OMS was chosen for facilitating model connectivity because of it low invasiveness in code practice and capability in production of leaner and more descriptive modelling code .
uDig as visualization/GIS platform, including GIS services, and its integration with the JGrass GIS, developed by http://udig.refractions.net/, offers a spatial toolbox which contains the features previously offered by JGrass.
Compared to traditional hydrological models, which are built upon monolithic code, JGrass-NewAge allows for multiple modelling solutions for the same physical process, provided they share similar input and outputs constraints. Modeling components are connected by means of a concise scripting language NewAge-JGrass components can be grouped in several categories.
The geomorphic and DEM analyses which solves the problem of basin delineation; the tools for making spatial extrapolation/interpolation of the meteorological data; the estimation of the radiation forcing; the estimation of evapotranspiration; the estimation of the runoff production; the channel routing and tools for automatic model parameter calibration such as DREAM, Particle Swarm and LUCA.
NewAge requires interpolated meteorological variables (such as air temperature, precipitation, and relative humidity) as input data for each hillslope. They can be computed by a deterministic or geostatistic approaches. The energy model includes both, shortwave and longwave radiation calculation components for each hillslope. The first implements algorithms that take into account shade and complex topography and cloud cover.
Evapotraspiration can be modelled using two different solutions: the Fao-Evapotraspiration model and the Priestley-Taylor model. A snow melting and snow water equivalent model is also part of the system. Duffy's model and Hymod model are the runoff production models implemented in NewAge. In both cases the model is applied for each hillslope. Finally, the discharge generated at each hillslope is routed to each associated stream link.
Modeling solutions (connections of different components) are applied in three different river basin and verifications against measured data (discharge, radiation fluxes, snow water equivalent) are presented by using traditional goodness of fitting indices
Linear and non linear coupling effects in sequence of microresonators
No full textMy work was carried out with the aim of devising and characterize novel integrated devices for signal routing in optical networks on chip. Several type of optical microresonators, both in a single and coupled configuration (CROW, SCISSOR), are discussed starting from the fundamental theory till dealing with novel configurations. The coupling between a Mach-Zehnder interferometer and such configuration of microresonators is also investigated. Since the used material platform is the silicon on insulator (SOI), an in depth study of the microresonators behaviour has demanded an investigation in both in the linear and non-linear regime.
All devices were fabricated through a standard CMOS facility by using deep UV lithography in order to verify the reliability of resolution and throughput similar to those required for commercial applications. Particular attention has been paid in the study of structures robust with respect to manufacturing defects.
All the steps necessary to develop a device for integrated optics are studied in deep: device conception, device simulations through analytic and FEM simulations, GDS mask design, experimental characterizations.
All the devices parameters are carefully reported to allow the reproduction of the experimental results. Where it was possible, suggestions on how to improve the fabricated devices performance were given
Stochastic Analysis of a resource reservation system
No full textAn unmistakable trend in embedded systems is the growth of
soft real-time computing. A soft real-time application is one for which deadlines can occasionally be missed, but the probability of this event has to be controllable and predictable.
This work is aimed to close the gap in the research of stochastic real-time analysis related to resource reservation scheduling algorithms. This dissertation attempts to:
1. give a quick overview of classic real-time analysis
2. analyze the problems related to use the well-known techniques in the context of soft real-time applications:
• overvalue the assignation of parameters as in hard real-
time systems based on worst case execution times
• time and memory complexity using the known theoretical
stochastic analysis
3. propose solutions able to overcome the limitation showed in point 2
4. show some specific examples (theoretical and practical) in which resource reservation lead to advantages.
The novel contributions of this thesis are:
• a new bound to predict the probability of a deadline misses in a resource reservation systems
• a very efficient numeric solution for matrix generated with well-know abstraction models of reservation based on Quasi Birth Death Markov Process
• an analytical solution, with some conservative approximations, for the same models.
• a new model for specific applications, like interrupts.
• experiments using resource reservation in different contexts
The thesis is evolved following two different approaches:
1. the first based on the exact model of reservation, and the contributions is:
• define a new pessimistic bound, efficient in term of computation, able to overcome the problem of complete knowledge of the computation time. The solution is an approximation of the real solution of the model.
2. the second based on an approximation model in which the
novel contributions are:
• presents an exact and numeric efficient solution for the
model based on Quasi Birth and Death Markov Process
• introduces an approximate analytical solution which can
be computed with no complexity and which is reversible
These techniques are applicable since the minimum interarrival of a request is greater than a server period. Unfortunately exists situations in which this assumption is not feasible. An important example is using resource reservation to scheduling interrupts. In order to consider also this situation, another important novel result of this thesis is:
• to introduce a new model for scheduling interrupts
In addition, some practical examples of using resource reservation are presented
Tra pratiche istituzionali, discorsi legali e dispositivi clinici: la narrazione nel processo di richiesta d'asilo. Un'indagine etnografica
No full textAttraverso questo elaborato s’intende proporre una riflessione critica, circa le valenze politicamente sottese all’utilizzo del dispositivo narrativo all’interno del percorso di richiesta d’asilo politico. Frutto di una ricerca etnografica condotta nel territorio bolognese all’interno di alcuni tra gli snodi principali che compongono questo percorso istituzionale, l’indagine in questione è stata svolta ricorrendo agli strumenti metodologici di cui l’etnografia si avvale.
Un intreccio complesso, composto dall’alternarsi di fasi tese al “controllo” delle trame presenti nelle storie dei richiedenti asilo e alla “produzione” delle caratteristiche che compongono questo specifico soggetto legale, può essere individuato come il fil rouge che lega le tre sezioni etnografiche sui cui si erigono le riflessioni oggetto di questo elaborato. Nella prima parte, infatti, è stato possibile mettere in luce, tramite l’etnografia condotta presso un servizio per il supporto alla Protezione Internazionale, come la storia venga trattata in quanto specchio dell’esperienza trascorsa dai richiedenti, dunque, come elemento da verificare e correggere al fine di mettere a punto un soggetto in grado di performare il ruolo istituzionale assegnatoli. La categoria di trauma viene chiamata in causa in questi contesti come strumento di controllo e di conferma delle trame narrative che richiamano esperienze di violenza o come elemento in grado di “riparare”, se presente nelle relazioni medico-psichiatriche, a quei “buchi di trama” e alla mancanza di linearità talvolta presente nei racconti degli applicanti. Dalla ricerca è emerso come le istituzioni d’asilo riconducano infatti queste imperfezioni narrative sia alla non autenticità delle storie, sia a particolari disfunzioni cognitive, riflesso di malfunzionamenti mnestici spesso concepiti come legati allo stesso concetto di esperienza traumatica. È in questo frangente che i dispositivi clinici di stampo psicologico – psichiatrico vengono eletti a pratica confessionale (Foucault, 2006) segmento di realtà iscrivibile in più ampie “memoro – politiche” (Hacking, 1996) tese al controllo e alla normalizzazione delle memorie e dunque, in questo caso specifico, dell’identità degli applicanti. Questi ultimi aspetti sono stati messi in luce nella seconda e terza delle tre sezioni etnografiche che compongono l’elaborato, rispettivamente frutto di due distinte fasi di osservazione partecipante condotte presso un centro di salute mentale e un servizio teso al collocamento lavorativo di richiedenti asilo e titolari di protezione internazionale gestito da personale con formazione in ambito psicologico