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Into the city: A Multi-Disciplinary Investigation of Urban Life
Full text linkCities are essential crucibles for innovation, novelty, economic prosperity and diversity. They are not a mere reflection of individual characteristics, but instead the result of a complex interaction between people and space. Yet, little is known about this self-organized and complex relationship. Traditional approaches have either used surveys to explain in detail how a few individuals experience bits of a city, or considered cities as a whole from their outputs (e.g. total crimes). This tide has however tuned in recent years: the availability of new sources of data have allowed to observe, describe, and predict human behaviour in cities at an unprecedented scale and detail. This thesis adopts a "data mining approach" where we study urban spaces combining new sources of automatically collected data and novel statistical methods. Particularly, we focus on the relationship between the built environment, described by census information, geographical data, and images, and human behaviour proxied by extracted from mobile phone traces. The contribution of our thesis is two-fold. First, we present novel methods to describe urban vitality, by collecting and combining heterogeneous data sources. Second, we show that, by studying the built environment in conjunction with human behaviour, we can reliably estimate the effect of neighbourhood characteristics, predict housing prices and crime. Our results are relevant to researchers within a broad range of fields, from computer science to urban-planning and criminology, as well as to policymakers. The thesis is structured in two parts. In the first part, we investigate what creates urban life. We operationalize the theory of Jane Jacobs, one of the most famous authors in urban planning, who suggested that the built environment and vitality are intimately connected. Using Web and Open data to describe neighbourhoods, and mobile phone records to proxy urban vitality, we show that it is possible to predict vitality from the built environment, thus confirming Jacob's theory. Also, we investigate the effect of safety perception on urban vitality by introducing a novel Deep Learning model that relies on street-view images to extract security perception. Our model describes how perception modulates the relative presence of females, elderly and younger people in urban spaces. Altogether, we demonstrate how objective and subjective characteristics describe urban life.
In the second part of this dissertation, we outline two studies that stress the importance of considering, at the same time, multiple factors to describe cities. First, we build a predictive model showing that objective and subjective neighbourhood features drive more than 20% of the housing price. Second, we describe the effect played by a neighbourhood's characteristics on the presence of crime. We present a Bayesian method to compare two alternative criminology theory, and show that the best description is achieved by considering together socio-economic characteristics, built-environment, and mobility of people. Also, we highlight the limitations of transferring what we learn from one city to another.
Our findings show that new sources of data, automatically sensed from the environment, can complement the lengthy and costly survey-based collection of urban data and reliably describe neighbourhoods at an unprecedented scale and breath. We anticipate that our results will be of interest to researchers in computer science, urban planning, sociology and more broadly, computational social science
Wake-up Radio based Approach to Low-Power and Low-Latency Communication in the Internet of Things
No full textFor the Internet of Things to flourish a long lasting energy supply for remotely deployed large- scale sensor networks is of paramount importance. An uninterrupted power supply is required by these nodes to carry out tasks such as sensing, data processing, and data communication. Of these, radio communication remains the primary battery consuming activity in wireless systems. Advances in MAC protocols have enabled significant lifetime improvements by putting the main transceiver in sleep mode for extended periods. However, the sensor nodes still waste energy due to two main issues. First, the nodes periodically wake-up to sample the channel even when there is no data for it to receive, leading to idle listening cost. On the other side, the sending node must repeatedly transmit packets until the receiver wakes up and acknowledges receipt, leading to energy wastage due to over-transmission. In systems with the low data rate, idle listening and over-transmission can begin to dominate energy costs. In this thesis, we take a novel hardware approach to eliminate energy overhead in WSNs by addition of a second, extremely low-power wake-up radio component. This approach leverages an always-on wake-up receiver to delegate the task of listening to the channel for a trigger and then waking up a higher power transceiver when required. With this on-demand approach, energy constrained devices are able to drastically reduce power consumption without sacrificing the application requirements in terms of reliability and network latency. As a first major contribution, we survey a large body of work to identify the benefits and limitations of the current wake-up radio hardware technology. We also present a new taxonomy for categorizing the wake-up radios and the respective protocols, further highlighting the main issues and challenges that must be addressed while designing systems based on wake-up radios. Our survey forms a guideline for assisting application and system designers to make appropriate choices while utilizing this new technology.
Secondly, this thesis proposes a first-ever benchmarking framework to enable accurate and repeatable profiling of wake-up radios. Specifically, we outline a set of specifications to follow when benchmarking wake-up radio-based systems, leading to more consistent and therefore comparable evaluations whether in simulation or testbed for current and future systems. To quantitatively assess whether wake-up technology can provide energy savings superior to duty cycled MACs, reliable tools are required to accurately model the wake-up radio hardware and its performance in combination with the upper layers of the stack. As our third contribution, we provide an open-source simulator, WaCo for development and evaluation of wake-up radio protocols across all layers of the software stack. Using our tool together with a newly proposed wake-up radio MAC layer, we provide an exhaustive evaluation of the wake-up radio system for periodic data collection applications. Our evaluations highlight that wake-up technology is indeed effective in extending the network lifetime by shrinking the overall energy consumption. To close the gap between the simulation and the real world experiments, we adopt a cutting edge wake-up radio hardware and build a Wake-up Lab, a modular dual-radio prototype. Using our Wake-up Lab, we thoroughly evaluate the performance of the wake-up radio solution in a realistic office environment. Our in-depth system-wide evaluation reveals that wake-up radio-based systems can achieve significant improvements over traditional duty cycling MACs by eliminating periodic receive checks and reducing unnecessary main radio transmissions while maintaining end-to-end latency on the order of tens of milliseconds in a multi-hop network. As a step toward sustainable wireless sensing, this thesis presents a proof of concept system where an extremely low-power switch coupled with a wake-up receiver is continuously powered by a plant microbial fuel cell (PMFC) and a new receiver-initiated MAC-level communication protocol for on-demand data collection. MFC converts the chemical energy into electricity by exploiting the metabolism of bacteria found in the sediment, thus offering a promising power source for autonomous sensing system. However, sources such as PMFCs are severely limited in the quantity of energy they can generate, unable to directly power the sensor nodes. Therefore, we consider radical hardware solutions in combination with the communication stacks to reduce this power gap. Thanks, to the hardware-software co-design proposed above, we were able to reduce the overall power consumption to a point where an extremely low-power PMFC source can sustain the sensor node’s operation with a data sampling rate of over 30 seconds. Finally, we propose to enhance the LoRa based low-power wide area networks by fusing wake-up receivers and long-range wireless technologies. The current LoRaWAN architecture is mainly designed and optimized for up-links where the remote end devices disseminate data to the gateway using pure ALOHA techniques. As such, this limits the ability of the gateway to control, reconfigure, or query the specific end devices, crucial for many Internet of Things applications. To shift the communication modality from push to pull based, we propose a new network architecture that leverages wake-up receiver and a receiver-initiated On-demand TDMA MAC. The former allows the gateway to trigger the remote device when there is data to be collected else keep the device in sleep mode, while the latter allows retrieving data efficiently from the nodes without congesting the network. Our testbed experiments reveal that the proposed system significantly improves energy efficiency by offering network reliability of 100% with end devices dissipating only a few microwatts of power during periods of inactivity. By moving away from the realm of pure ALOHA communication to wake-up receivers, we were able to exploit the low power modes of the sensor node more effectively. Through these contributions, this thesis pushes forward the applicability of ultra-low power wake-up radios, by quantitatively measuring the trade-offs, energy efficiency, reliability, and latency. Further, by demonstrating superior performance via proof of concepts, this thesis provides a stepping stone towards the goal of achieving energy-neutral, yet responsive communication systems using wake-up radio technology
Consequences of Environmental Degradation in Developing Countries
Full text linkAlthough climate change is a global phenomenon affecting populations from countries at varying stages of development, a few of its consequences gain significantly more salience for less developed countries, specifically. I focus on the adverse effects of environmental degradation for two main reasons. On the one hand, it is my impression that the increased vulnerability of less developed countries to adverse environmental degradation needs more attention by scholars (Biermann and Moeller, 2019). On the other hand, climate change is of the most pressing problems of our time, for which we have little time to act (IPCC, 2018) and whose consequences weight on the shoulders of many future generations. In other terms, the environment is deteriorating fast, and not only this is occurring faster in developing countries than in industrialised ones, the former are also less capable to protect against it for institutional, technological, and financial reasons (Barbier, 2010; Blaikie, 2016).
The asymmetry of environmental deterioration and of its effects is observable in many indicators. For instance, soil erosion is affecting ever larger areas, most of them in developing countries, whose institutions are not able or willing to intervene (Blaikie, 2016). Soil erosion mainly affects farmers and their productivity, but in developing countries they do not have the financial and technological means to defend themselves (Barbier, 2010; Blaikie, 2016), which induces some of them to resort to migration (when possible) (Blaikie 2016). Farmers trying to adapt to the erosion of soil may adopt coping strategies that endanger the sustainability of proximate water basins, fisheries (for instance, see Dejen et al., 2017) and of forestry (see Wondie, 2010). These practices ultimately undermine the sustainable extraction of natural resources and thus the long term productivity of the related activities. In these few introductory lines, I touched upon the issues I decided to investigate in this doctoral thesis: adaptation strategies and their possible negative side effects, inequality in the consequences of and in the means to face environmental degradation, and the long term effects of the latter on productivity. In my opinion, these are three very relevant pathways connecting environmental degradation to hindrances and obstacles to sustainable development of less developed countries. In the three chapters constituting the thesis, I investigate the economic dimensions of the problems above mentioned
Optimization Modulo Theories with OptiMathSAT
Full text linkIn the contexts of Formal Verification (FV) and Automated Reasoning (AR), Satisfiability Modulo Theories (SMT) is an important discipline that allows for dealing with industrial-level decision problems. Optimization Modulo Theories (OMT) extends Satisfiability Modulo Theories
with the ability to express, and optimize, objective functions.
Recently, there has been a growing interest towards OMT, as witnessed by an increasing number of applications using, at their core, some OMT solver as main power-horse engine.
However, at present few OMT solvers exist, and the development of OMT technology is still at an early stage, with large margins of improvement. We identify two major advancement directions in particular. First, there is a general need for closing the expressiveness gap with respect to SMT, and provide optimization procedures that can deal with the wider range of theories supported by SMT solvers. Second, there is an urgent need for more efficient techniques that can improve on the performance of state-of-the-art OMT solvers, because solving an OMT problem is inherently more expensive than dealing with its SMT counterpart, often by at least one order of magnitude.
In this dissertation, we present a variety of techniques that deal with the identified issues and advance both the expressiveness and the efficiency of OMT. We describe our implementation of these techniques inside OptiMathSAT, a state-of-the-art OMT solver based on MathSAT5, along with its high-level architecture, Input/Output interfaces and configurable options.
Thanks to our novel contributions, OptiMathSAT can now deal with the single- and the multi-objective incremental optimization of goals defined over multiple domains –the Boolean, the mixed Linear Integer and Rational Arithmetic, the Bit-Vector and the Floating Point domain– including (Partial Weighted) MaxSMT.
We validate our theoretical contributions experimentally, by comparing the performance of OptiMathSAT against other, competing, OMT solvers. Finally, we investigate the effectiveness of OMT beyond the scope of Formal Verification, and describe an experimental evaluation
comparing OptiMathSAT with Finite Domain Constraint Programming tools on benchmark-sets coming from their respective domains
Eye controlled semi-Robotic Wheelchair for quadriplegic users embedding Mixed Reality tools
Full text linkMobile assistive robotics can play a key role to improve the autonomy and lifestyle of patients. In this context, RoboEye project aims to support people affected by mobility problems that range from very impairing pathologies (like ALS, amyotrophic lateral sclerosis) to old age.
Any severe motor disability is a condition that limits the capability of interacting with the environment, even the domestic one, caused by the loss of the control on our own mobility. Although these pathologies are relatively rare, the number of people affected by this disease are increasing during the years.
The focus of this project is the restore of persons’ mobility using novel technologies based on the gaze on a power wheelchair designed to enable the user to move easily and autonomously inside his home.
A novel and intuitive control system was designed to achieve such a goal, in which a non-invasive eye tracker, a monitor, and a 3D camera represent some of the core elements.
The developed prototype integrates, on a standard power wheelchair, functionalities from the mobile robotics field, with the main benefit of providing to the user two driving options and comfortable navigation.
The most intuitive, and direct, modality foresees the continuous control of the frontal and angular velocities of the wheelchair by gazing at different areas of the monitor.
The second, semi-autonomous, enables the navigation toward a selected point in the environment by just pointing and activating the wished destination while the system autonomously plans and follows the trajectory that brings the wheelchair there. The main goal is the development of shared control, combining direct control by the user with the comfort of autonomous navigation based on augmented reality markers.
A first evaluation has been performed on a real test bed where specific motion metrics are evaluated. The designs of the control structure and driving interfaces were tuned thanks to the testing of some volunteers, habitual users of standard power wheelchairs.
The driving modalities, especially the semi-autonomous one, were modelled and qualified to verify their efficiency, reliability, and safety for domestic usage
Efficient Motion Planning for Wheeled Mobile Robotics
Full text linkNowadays, the field of wheeled robotics is undergoing an impressive growth and development. Different hardware and software components are being developed and applied in various contexts, including assistive robotics, industrial robotics, automotive, ...
Motion Planning is a fundamental aspect for the development of autonomous wheeled mobile robots.
The capability of planning safe, smooth trajectories, and to locally adjust them in real-time to deal with contingent situations and avoid collisions is an essential requirement
to allow robots to work and perform activities in public spaces shared with humans.
Moreover, in general, efficiency is a key constraint for this kind of applications, given the limited computational power usually available on robotic platforms.
In this thesis, we focus on the development of efficient algorithms to solve different kind of motion planning problems. Specifically, in the first part of the thesis, we propose a complete planning system for an assisitive
robot supporting the navigation of older users. The developed planner generates paths connecting different locations on the map, that are smooth and specifically tailored to optimize the comfort perceived by the human users. During the navigation, the system applies an efficient model to predict the behaviours of the surrounding pedestrians, and to locally adapt the reference path to minimise the probability of collisions. Finally, the motion planner is integrated with an "high-level" reasoning component, to generate and propose complete activities, like the visit to a museum or a shopping mall, specifically tailored to the preferences, needs and requirements
of each user.
In the second part of the thesis, we show how the efficient solutions and building blocks developed for the assistive robots, can be adapted and applied also to a completely different context, such as the generation of optimal trajectories for an autonomous racing vehicle
Mechanics and numerical simulations of Dry Granular Flows driven by gravity
Full text linkThe gravitational granular flows (e.g. debris flows or snow avalanches) are catastrophic and destructive phenomena affecting many areas in the world, and especially the mountain areas of Europe. Proper design criteria are required in order to improve protection structures and prevention strategies. Due to their complex nature, these phenomena present many aspects still unsolved in the research field.
This research addresses some aspects of the mechanics of dry granular flows: a 1D depth integrated model has been developed, based on a two phase approach. The system of equations consists of three partial differential equations, derived from the mass balances for the solid and fluid phase and from the momentum balance for the solid phase, and two rheological relations determined through experimental tests and particle numerical simulations. The experimental investigation hes been conducted in a laboratory channel, by recording through high speed cameras the motion of polystyrene spherical particles. Within this research, it has been developed an ad hoc optical method to analyze and process the images recorded, with the aim of defining the main flow characteristics. From a numerical point of view, a path conservative finite volume scheme has been adopted to solve the system of equations previously described: the numerical solution is compared to the experimental results for different configurations, in order to verify the effectiveness of the mod
The Twenty-First Century Mechanistic Theory of Human Cognition: A Critical Appraisal
Full text linkThe Mechanistic Theory of Human Cognition (MTHC) is currently one of the most influential fundamental theories in the field of cognitive science. The main idea is to provide an account of what human neuro-cognitive complex mechanisms are and how to explain them. The theory proposes an ambitious revolutionary unified view of human cognition that can provide foundations and theoretical unification within cognitive science and between cognitive science and relevant portions of neuroscience. However, this proposal faces many challenges. The central objective of this work is to make a theoretical critical appraisal of MTHC. I critically analyse and evaluate whether MTHC provides a unifying account of human cognition and its explanation for cognitive science. I argue that MTHC provides a significant theoretical contribution for the field; however, it cannot offer the ambitious revolutionary integration that some of its most influential advocates promise
Die Vernünftigkeit der Gefühle. Hegel e il contemporaneo dibattito sulle emozioni
Full text linkScopo del presente lavoro è dimostrare che Hegel, benché sia assente dal contemporaneo dibattito filosofico, psicologico e neuroscientifico sulle emozioni, non si è disinteressato alle componenti della Gefühlssphäre e al loro valore conoscitivo. Terreno privilegiato ma non esclusivo d’indagine sono le sezioni antropologica e psicologica dell’Enzyklopädie (1830), nelle quali Hegel indaga tematiche che sono al centro degli interessi della contemporanea filosofia della mente e della psicologia filosofica, quali l’essere incarnata dell’anima, l’espressione delle emozioni e il loro fondamento fisiologico, l’abitudine, la volontà e, appunto, Empfindungen, Gefühle, Triebe, Neigungen e Leidenschaften. La delineazione delle caratteristiche fondamentali delle componenti della Gefühlssphäre ha consentito di comprendere “cosa” siano Empfindungen, Gefühle, Neigungen e Leidenschaften, come insorgano nell’uomo, “quale funzione” Hegel accordi loro e “perché”. La risposta a tali domande, unitamente a una ricostruzione dei diversi livelli entro cui entrano in gioco, nella Philosophie des subjektiven Geistes, le suddette componenti, ha infine permesso di delineare la “Theorie des Gefühls” hegeliana. Ciò che questa articolata “teoria” suggerisce è il ruolo fondamentale ricoperto dalla Gefühlssphäre nel processo di sviluppo che conduce l’anima naturale a riconoscersi come uno spirito che si pone degli scopi e che cerca di tradurli nel mondo esterno attraverso azioni. È però il rapporto di continuità individuato da Hegel tra Gefühl e cognizione ad approssimare la sua teoria ai più recenti studi sulle emozioni. Il lavoro si propone di mostrare come i Gefühle, intesi quali fenomeni psichici complessi, implichino secondo Hegel sia le valutazioni cognitive che il soggetto fa, di situazioni e cose in rapporto al proprio benessere e alla propria soddisfazione, sia un’attivazione fisiologica dell’organismo a cui segue l’espressione delle risposte emotive e la preparazione all’azione. I Gefühle sono quindi concepiti da Hegel quali momenti costitutivi dello sviluppo di attività razionali e sono strumenti necessari al soggetto per orientarsi nel mondo. Poiché Hegel riconosce l’importanza della Gefühlssphäre del soggetto (sempre concepito come soggetto incarnato) e dà rilievo al valore conoscitivo dei Gefühle, questo lavoro si propone infine di mostrare come egli possa rappresentare un importante interlocutore per le contemporanee trattazioni sulle emozioni, che insistono sulla connessione che sussiste tra emozione, ragione e tendenza all’azione
Domain Modeling Theory and Practice
Full text linkEveryday huge amount of data is being captured and stored. This can either be due to several social initiatives, technological advancement or by smart devices. This involves the release of data which differs in format, language, schema and standards from various types of user communities and organizations. The main challenge in this scenario lies in the integration of such diverse data and on the generator of knowledge from the existing sources. Various methodology for data modeling has been proposed by different research groups, under different approaches and based on the scenarios of the different domain of application. However, a few methodology elaborates the proceeding steps. As a result, there is lack of clarification how to handle different issues which occurs in the different phases of domain modeling. The aim of this research is to presents a scalable, interoperable, effective framework and a methodology for data modeling. The backbone of the framework is composed of a two-layer, schema and language, to tackle diversity. An entity-centric approach has been followed as a main notion of the methodology. A few aspects which have especially been emphasized are: modeling a flexible data integration schema, dealing with the messy data source, alignment with an upper ontology and implementation. We evaluated our methodology from the user perspective to check its practicability