18 research outputs found

    Correct-by-Construction Development of Dynamic Topology Control Algorithms

    Get PDF
    Wireless devices are influencing our everyday lives today and will even more so in the future. A wireless sensor network (WSN) consists of dozens to hundreds of small, cheap, battery-powered, resource-constrained sensor devices (motes) that cooperate to serve a common purpose. These networks are applied in safety- and security-critical areas (e.g., e-health, intrusion detection). The topology of such a system is an attributed graph consisting of nodes representing the devices and edges representing the communication links between devices. Topology control (TC) improves the energy consumption behavior of a WSN by blocking costly links. This allows a mote to reduce its transmission power. A TC algorithm must fulfill important consistency properties (e.g., that the resulting topology is connected). The traditional development process for TC algorithms only considers consistency properties during the initial specification phase. The actual implementation is carried out manually, which is error prone and time consuming. Thus, it is difficult to verify that the implementation fulfills the required consistency properties. The problem becomes even more severe if the development process is iterative. Additionally, many TC algorithms are batch algorithms, which process the entire topology, irrespective of the extent of the topology modifications since the last execution. Therefore, dynamic TC is desirable, which reacts to change events of the topology. In this thesis, we propose a model-driven correct-by-construction methodology for developing dynamic TC algorithms. We model local consistency properties using graph constraints and global consistency properties using second-order logic. Graph transformation rules capture the different types of topology modifications. To specify the control flow of a TC algorithm, we employ the programmed graph transformation language story-driven modeling. We presume that local consistency properties jointly imply the global consistency properties. We ensure the fulfillment of the local consistency properties by synthesizing weakest preconditions for each rule. The synthesized preconditions prohibit the application of a rule if and only if the application would lead to a violation of a consistency property. Still, this restriction is infeasible for topology modifications that need to be executed in any case. Therefore, as a major contribution of this thesis, we propose the anticipation loop synthesis algorithm, which transforms the synthesized preconditions into routines that anticipate all violations of these preconditions. This algorithm also enables the correct-by-construction runtime reconfiguration of adaptive WSNs. We provide tooling for both common evaluation steps. Cobolt allows to evaluate the specified TC algorithms rapidly using the network simulator Simonstrator. cMoflon generates embedded C code for hardware testbeds that build on the sensor operating system Contiki

    Effects of Virtual Hand Representation on Interaction and Embodiment in HMD-based Virtual Environments Using Controllers

    Get PDF
    Τα τελευταία χρόνια, έχουν γίνει αρκετές έρευνες που επικεντρώνονται στην αλληλεπίδραση με και την αίσθηση της "ενσωμάτωσης" σε περιβάλλοντα Εικονικής Πραγματικότητας (Virtual Reality - VR). Παρόλα αυτά, σε αντίθεση με την πρόσφατη ευρεία χρήση και συνεχόμενη άνοδο του υλικού εικονικής πραγματικότητας που είναι βασισμένο σε κάσκες (HMDs) και χειριστήρια, η έρευνα σχετικά με την χρήση αυτών των χειριστηρίων είναι περιορισμένη. Για να αντιμετωπίσουμε αυτήν την έλλειψη, διερευνήσαμε τις επιδράσεις που έχουν διαφορετικές αναπαραστάσεις εικονικού χεριού στην αλληλεπίδραση με την χρήση χειριστηρίων και την αίσθηση ενσωμάτωσης των χρηστών, εμπνεόμενοι από τη δουλειά του Argelaguet κ.ά. το 2016, που όμως δεν χρησιμοποίησαν χειριστήρια στα πειράματά τους. Σχεδιάσαμε ένα πείραμα όπου οι χρήστες εκτελούν την εργασία της επιλογής και μετακίνησης ενός κύβου από και προς συγκεκριμένες θέσεις πάνω σε ένα τραπέζι, ενώ βρίσκονται μέσα σε ένα εμβυθιστικό εικονικό περιβάλλον. Τρεις αναπαραστάσεις επιλέχθηκαν: το αφαιρετικό σχήμα μιας Σφαίρας, το τρισδιάστατο μοντέλο του Χειριστηρίου, το οποίο αποτελεί ένα-προς-ένα αναπαράσταση αυτού που οι χρήστες έχουν στα χέρια τους στο φυσικό κόσμο, και ένα ανθρωπόμορφο Χέρι, η πιο ρεαλιστική και οικεία αναπαράσταση από τις τρεις. Για κάθε μια αναπαράσταση, ζητήθηκε από τους χρήστες να εκτελέσουν την ίδια εργασία χωρίς και με εμπόδια (Τούβλινος Τοίχος, Συρματόπλεγμα, Ηλεκτρικό Ρεύμα). Συνολικά 39 συμμετέχοντες, που ανήκουν σε ποικίλες ηλικιακές ομάδες και έχουν διαφορετικά επίπεδα εμπειρίας σε VR, πήραν μέρος στη μελέτη. Η σχεδίαση και τα αποτελέσματα του πειράματος παρουσιάζονται στην παρούσα διπλωματική, αναφέροντας σημαντικές διαφορές στην πραγματική απόδοση των διαφορετικών αναπαραστάσεων, της αντιληπτής αίσθησης ιδιοκτησίας, καθώς επίσης και στις προτιμήσεις των χρηστών. Αν και δεν παρατηρήθηκαν σημαντικές διαφορές στην αίσθηση αυτενέργειας, η απόδοση των χρηστών με τη Σφαίρα ήταν σημαντικά χειρότερη σε σύγκριση με τις άλλες δύο αναπαραστάσεις. Η στατιστική ανάλυση των αποτελεσμάτων δείχνει ότι το Χέρι είναι εκείνο που δημιουργεί την ισχυρότερη αίσθηση ιδιοκτησίας, και είναι η προτιμότερη αναπαράσταση. Αυτό την κάνει την καλύτερη συνολική λύση κατά τη σχεδίαση αλληλεπιδραστικών εικονικών περιβαλλόντων με χειριστήρια, συνδυάζοντας καλή απόδοση και αυξημένη αίσθηση ιδιοκτησίας, με εξαίρεση περιπτώσεις που απαιτούν πολύ ακριβείς χειρισμούς αντικειμένων όπου το Χειριστήριο είναι η καλύτερη επιλογή.Many studies have been conducted in the past few years that focus on interaction and embodiment in the field of Virtual Reality (VR). However, despite the recent widespread use and continuing rise of controller-based head-mounted display (HMD) hardware for VR, there is little research on the use of handheld controllers in this context. To address this shortcoming, we explore the effects of different virtual hand representations on interaction and the user’s sense of embodiment, inspired by the work of Argelaguet et al. in 2016, in this case using controllers. We designed an experiment where users perform the task of selecting and moving a cube from and to specific positions on a table inside an immersive virtual environment. Three representations were selected: the abstract shape of a Sphere, the 3D model of the Controller, which is a one-to-one representation of what the users have in their hands in the physical world, and a human-looking Hand, the most realistic and familiar of the three. For each representation, users were asked to perform the same task with and without obstacles (Brick Wall, Barbed Wire, Electric Current). A total of 39 participants, belonging to various age groups and having different levels of experience in VR, took part in the study. The design and results of the experiment are presented in this thesis, reporting significant differences in the actual performance of the different representations, the perceived sense of ownership, as well as the users’ preferences. Although no significant differences were identified in the sense of agency, the users’ performance with the Sphere was significantly worse compared to the other two. Statistical analysis of the results indicates that it is the Hand that generates the strongest sense of ownership, and it is the favorite representation. This makes it the best solution overall when designing interactive virtual environments with controllers, combining good performance with enhanced sense of ownership, with the exception of cases requiring very precise object manipulation in which the Controller is the best option

    Re-manufacturing networks for tertiary architectures

    Get PDF
    This book deals with re-manufacturing, recondition, reuse and repurpose considered as winning strategies for boosting regenerative circular economy in the building sector. It presents many of the outcomes of the research Re-NetTA (Re-manufacturing Networks for Tertiary Architectures). New organisational models and tools for re-manufacturing and re-using short life components coming from tertiary buildings renewal, funded in Italy by Fondazione Cariplo for the period 2019-2021. The field of interest of the book is the building sector, focusing on various categories of tertiary buildings, characterized by short term cycles of use. The book investigates the most promising strategies and organizational models to maintain over time the value of the environmental and economic resources integrated into manufactured products, once they have been removed from buildings, by extending their useful life and their usability with the lower possible consumption of other materials and energy and with the maximum containment of emissions into the environment. The text is articulated into three sections. Part I BACKGROUND introduces the current theoretical background and identifies key strategies about circular economy and re-manufacturing processes within the building sector, focusing on tertiary architectures. It is divided into three chapters. Part II PROMISING MODELS outlines, according to a proposed framework, a set of promising circular organizational models to facilitate re-manufacturing practices and their application to the different categories of the tertiary sectors: exhibition, office and retail. This part also reports the results of active dialogues and roundtables with several categories of operators, adopting a stakeholder perspective. Part III INSIGHTS provides some insights on the issue of re-manufacturing, analyzed from different perspectives with the aim of outlining a comprehensive overview of challenges and opportunities for the application of virtuous circular processes within building sector. Part III is organized in four key topics: A) Design for Re-manufacturing; B) Digital Transformation; C) Environmental Sustainability; D) Stakeholder Management, Regulations & Policies

    Globalising a design heritage strategy : from Finland's Artek to Turkey's Grand Bazaar

    Get PDF
    This doctoral study argues that the historical assets of design, engraved in living forms of collective memory, can be effectively engaged in the service of the appropriation and promotion of slower modes of consumption as opposed to the dominant and systematic novelty mechanism of fast fashion. The hypothesis is that a sustainability strategy employing design heritage and encouraging durable consumption can be helpful to avoid conflicts of interest between the transforming business community and its customers. Therefore, a heritage management strategy is proposed that emphasises feasibility and taps into existing socio- and politico-economic networks while suggesting positive changes in consumer behaviour. Due to the commercial and cultural popularity of permanent valorisation in design, this special design phenomenon is chosen as a specific field of design heritage. The potentials of enduring artefacts are recognised, and the study proposes further that these artefacts may become vehicles to achieve the strategy identified. To this end, the study employs an interdisciplinary review of several relevant literatures, transferring concepts and categories into the context of design heritage management. The findings of this review are further engaged in the analysis of a real-world case: the 2nd Cycle project by the iconic Finnish housewares company Artek. The analysis illustrates how the long-established company’s cultural and historical products are reproduced and capitalised in conformity with emerging consumer aspirations and needs. Drawing links between permanent valorisation, product longevity, and ultimately sustainable consumption, Artek’s project provides inspiring results how design heritage may lead to enhanced social good while taking advantage of new economic opportunities, know-how, and human capacities. Subsequently, special attention is given to the potential cross-cultural transferability of the heritage management strategy represented by this Finnish case. For this purpose, Artek’s case is taken as a cultivation of new sensibilities capable of translating a diversity of historical capital possessed by different cultures into heritage. Considering the constant growth of economic capacities and alarming levels of consumer spending, developing countries, known as emerging markets, are chosen as adaptation areas. Turkey, for example, whose historical, social, and cultural structure is distinct from that of Finland, provides a favourably challenging test environment for the thesis’ applicability. Discussing the feasibility and necessity of the growing heritage-oriented ethos in Turkey, the country is presented as representative of large emerging market segments with a theoretical application case, that of Istanbul’s monumental Grand Bazaar. Inspired by the Finnish case and developed further with additional insight from cultural heritage management studies in tourism environments, a specific design heritage management strategy is outlined for the bazaar. Following in-depth interviews with a range of professionals who make their living in the bazaar, and responding to their insights, the hypothetical strategy is aimed to synthesise the various interests of the bazaar’s large network of stakeholders while promoting durable consumption. Finally, a list of guiding principles of cross-cultural adaptation are drawn for future adopters attempting to apply this study’s findings to different heritage contexts on a global scale

    Creole Citizens of France: The Trans-Atlantic Politics of Antillean Education and the Creole Movement since 1945.

    Full text link
    This dissertation explores the debates about Creole’s place in the French nation and public education in late twentieth-century France. In 1946, Antilleans became French citizens when the French government decided to change Guadeloupe and Martinique’s political status from colonies to overseas departments (DOM). Republican education and the dissemination of French was the means through which DOM and education officials sought to protect France’s national culture and assimilate Antilleans’ Creole culture and language into the nation. In contrast, Antillean Creole activists envisioned a culturally diverse France. They struggled to reshape the national curriculum, and ultimately the French nation, so that it included their Creole culture and language. Through an examination of Antilleans’ specific case and how they used the Creole debates to argue for the right to difference, this dissertation explores the complexities of the discussions about diversity in France. Recently, historians have challenged the myth of a colorblind Republic, arguing that questions of race and ethnicity have shaped the French nation. While one group of scholars argues that exclusion occurred from the failure of state officials to live up to the lofty ideals of republican equality, the other group claims that inequality and exclusion developed as a part of republicanism. This dissertation argues that republican assimilation was not a monolithic policy that either entirely included or excluded difference from the nation. Rather, Antillean activists and the Ministries of the DOM and Education negotiated the terms of Antilleans’ assimilation and the extent to which the Creole culture and language was included in public classrooms and the nation. Antilleans’ demands for cultural inclusion forced DOM and education officials to carve out a space for difference, and more specifically, Creole, in the nation. I argue that it was these debates about the “Creole question” that challenged the republican definition of a French citizen as an individual divested of all particular and group affiliations. In highlighting Antilleans’ struggle to be both French and Creole, I contend that government policies concerning the right to difference were not only shaped by state ministries, but also by the actions of Antilleans on both sides of the Atlantic.Ph.D.HistoryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91374/1/smmcderm_1.pd

    Policy Performance and Governance Capacities in the OECD and EU. Sustainable Governance Indicators 2018. Bertelsmann Studies

    Get PDF
    This year marks the release of the third edition of the Sustainable Governance Indicators (SGI). The highly developed industrial nations continue to face enormous challenges, due not only to aftereffects of the global economic and financial crisis and the associated labor-market and sociopolitical upheavals. In other areas too, these nations look forward to a future rife with complex problems. Aging and shrinking populations, environmental and climatic changes, and social, cultural and technological shifts are placing democracies under massive pressure to adapt. As early as the first edition of the SGI, it was evident that despite often-similar reform pressures, political systems’ approaches and track records show significant variance. And in times of advancing globalization, the need for effective governance driven by capable leadership remains important. The previous SGI editions have also underscored the fact that this steering capability depends critically on the ability to combine short-term responsiveness with long-term resolve in policymaking

    Community participation in Boston's Southwest Corridor Project : a case study

    Get PDF
    Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1981.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 236-240.by Mauricio Miguel Gaston.M.C.P

    Fragile Energy: Power, Nature, And The Politics Of Infrastructure In The ‘New Turkey’

    Get PDF
    University of Minnesota Ph.D. dissertation. August 2016. Major: Sociology. Advisor: Michael Goldman. 1 computer file (PDF); ix, 216 pages.This dissertation provides a reading of political power in twenty-first century Turkey through the lens of (energy) infrastructures. By tracing the country’s bourgeoning energy infrastructures along their material, legal and financial dimensions, I examine energy’s ability to do political work and securing societal consent in Turkey, at a time when the idea of development is being privatized and the challenge of climate change encounters the country’s growing energy deficit. Relying on ethnographic and other qualitative methods collected along the path of energy infrastructures—including corridors of the bureaucracy, investment banks, construction sites, ribbon-cutting ceremonies, energy expos, local courthouses as well as electricity grids and hydropower penstocks—I argue that energy has played an under-recognized yet influential role in the establishment and sustenance of an authoritarian neoliberal experience, what is being dubbed by its founders, the ‘new Turkey’. Rather than collapsing the power harnessed from energy resources with political power, I introduce energy as a form of governmental rationality in the new Turkey that seeps into other realms of government from urban governance to counter-terrorism. The prowess of this emergent rationality, which I name as energorationality, stems from energy’s unique qualities in bringing center and periphery, urban and countryside, capital and commons together, from its ability to suture a variety of unlikely actors, policies, and ideas to each other. By examining grassroots mobilizations struggling against energy infrastructures in Turkey’s rural Eastern Black Sea Region (EBSR), I also discuss the fragility of energorationality. Mining disasters, unexpected droughts, unreliable projections, unruly villagers and urban riots, put delicate project cycles into disarray. I illustrate throughout the dissertation how energy infrastructures—small hydropower plants (small hydro, or SHP) in particular—, cause unexpected cracks as well as powerful sociopolitical alliances while converting uncharted rural and environmental settings into energy landscapes
    corecore