An Acyl-NHC Osmium Cooperative System: Coordination of Small Molecules and Heterolytic B–H and O–H Bond Activation

The hexahydride complex OsH6(PiPr3)2 (1) activates the C–OMe bond of 1-(2-methoxy-2-oxoethyl)-3-methylimidazolium chloride (2), in addition to promoting the direct metalation of the imidazolium group, to afford a five-coordinate OsCl(acyl-NHC)(PiPr3)2 (3) compound. The latter coordinates carbon monoxide, oxygen, and molecular hydrogen to give the corresponding carbonyl (4), dioxygen (5), and dihydrogen (6) derivatives. Complex 3 also promotes the heterolytic bond activation of pinacolborane (HBpin), using the acyl oxygen atom as a pendant Lewis base. The hydride ligand and the Bpin substituent of the Fischer-type carbene of the resulting complex 7 activate the O–H bond of alcohols and water. As a consequence, complex 3 is a metal ligand cooperating catalyst for the generation of molecular hydrogen, by means of both the alcoholysis and hydrolysis of pinacolborane, via the intermediates 7 and 6.

Arginine vasotocin regulation of interspecific cooperative behaviour in a cleaner fish

In an interspecific cooperative context, individuals must be prepared to tolerate close interactive proximity to other species but also need to be able to respond to relevant social stimuli in the most appropriate manner. The neuropeptides vasopressin and oxytocin and their non-mammalian homologues have been implicated in the evolution of sociality and in the regulation of social behaviour across vertebrates. However, little is known about the underlying physiological mechanisms of interspecific cooperative interactions. In interspecific cleaning mutualisms, interactions functionally resemble most intraspecific social interactions. Here we provide the first empirical evidence that arginine vasotocin (AVT), a non-mammalian homologue of arginine vasopressin (AVP), plays a critical role as moderator of interspecific behaviour in the best studied and ubiquitous marine cleaning mutualism involving the Indo-Pacific bluestreak cleaner wrasse Labroides dimidiatus. Exogenous administration of AVT caused a substantial decrease of most interspecific cleaning activities, without similarly affecting the expression of conspecific directed behaviour, which suggests a differential effect of AVT on cleaning behaviour and not a general effect on social behaviour. Furthermore, the AVP-V1a receptor antagonist (manning compound) induced a higher likelihood for cleaners to engage in cleaning interactions and also to increase their levels of dishonesty towards clients. The present findings extend the knowledge of neuropeptide effects on social interactions beyond the study of their influence on conspecific social behaviour. Our evidence demonstrates that AVT pathways might play a pivotal role in the regulation of interspecific cooperative behaviour and conspecific social behaviour among stabilized pairs of cleaner fish. Moreover, our results suggest that the role of AVT as a neurochemical regulator of social behaviour may have been co-opted in the evolution of cooperative behaviour in an interspecific context, a hypothesis that is amenable to further testing on the potential direct central mechanism involved.

Literature review on recent international activity in cooperative vehicle-highway automation systems /

This literature review supports the report, Recent International Activity in Cooperative Vehicle-Highway Automation Systems. It reviews the published literature in English dating from 2007 or later about non-U.S.-based work on cooperative vehicle-highway automation systems. This review covers work performed in Europe and Japan, with application to transit buses, heavy trucks, and passenger cars. In addition to fully automated driving of the vehicles (without human intervention), it also covers partial automation systems, which automate subsets of the total driving process. Recent International Activity in Cooperative Vehicle Highway Automation Systems is published separately as FHWA-HRT-12-033.

Learner support and discovery in a virtual non-judgmental environment

This thesis is a qualitative case study that draws upon a grounded genre analysis approach situated within the social constructivist paradigm. The study describes the various obligatory, desired, and optional moves used by post-graduate students as they interacted within an online, non-judgmental environment in order to seek solutions to issues they were experiencing with their research projects or teaching. The postgraduate students or case participants met individually online with me at pre-arranged times to take part in Instant Messenger Cooperative Development (IMCD) (Boon, 2005) 30-minute to one hour sessions via the text-chat function of Skype. Participants took on the role of ‘Explorer’ in order to articulate their thoughts and ideas about their research. I took on the role of ‘Understander’ to provide support to each Explorer by reflecting my understanding of the ongoing articulations as the Explorers investigated their specific issues, determined possible ways to overcome them, made new discoveries, and formulated plans of action regarding the best way for them to move forward. The description of generic moves covers 32 IMCD sessions collected over a threeyear period (2009-2012) from 10 different participants (A-J). Data collected is drawn from live IMCD sessions, field notes, and post-session email feedback from participants. In particular, the thesis focuses on describing the specific generic moves of Explorers within IMCD sessions as they seek satisfactory resolutions to particular research or pedagogic puzzles. It also provides a detailed description of a longitudinal case (Participant A – four sessions), a one-session case (Participant B – one session), and an outlier case in which the Explorer underwent a negative IMCD experience. The thesis concludes by arguing that IMCD is a highly effective tool that helps facilitate the research process for both distance-learning and on-campus students and has the potential to be utilized across all disciplines at the tertiary level.

Cooperative routing for collision minimization in wireless sensor networks

Cooperative communication has gained much interest due to its ability to exploit the broadcasting nature of the wireless medium to mitigate multipath fading. There has been considerable amount of research on how cooperative transmission can improve the performance of the network by focusing on the physical layer issues. During the past few years, the researchers have started to take into consideration cooperative transmission in routing and there has been a growing interest in designing and evaluating cooperative routing protocols. Most of the existing cooperative routing algorithms are designed to reduce the energy consumption; however, packet collision minimization using cooperative routing has not been addressed yet. This dissertation presents an optimization framework to minimize collision probability using cooperative routing in wireless sensor networks. More specifically, we develop a mathematical model and formulate the problem as a large-scale Mixed Integer Non-Linear Programming problem. We also propose a solution based on the branch and bound algorithm augmented with reducing the search space (branch and bound space reduction). The proposed strategy builds up the optimal routes from each source to the sink node by providing the best set of hops in each route, the best set of relays, and the optimal power allocation for the cooperative transmission links. To reduce the computational complexity, we propose two near optimal cooperative routing algorithms. In the first near optimal algorithm, we solve the problem by decoupling the optimal power allocation scheme from optimal route selection. Therefore, the problem is formulated by an Integer Non-Linear Programming, which is solved using a branch and bound space reduced method. In the second near optimal algorithm, the cooperative routing problem is solved by decoupling the transmission power and the relay node se- lection from the route selection. After solving the routing problems, the power allocation is applied in the selected route. Simulation results show the algorithms can significantly reduce the collision probability compared with existing cooperative routing schemes.

Outage performance of cognitive cooperative networks with relay selection over double-Rayleigh fading channels

This study considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all
communication links are non-line of sight ones and their fading is modelled by the double Rayleigh fading distribution.
Road-side relays (or access points) implementing the decode-and-forward relaying protocol are employed and one of
them is selected according to a predetermined policy to enable communication between vehicles. The performance of
the considered cognitive cooperative system is investigated for Kth best partial and full relay selection (RS) as well as
for two distinct fading scenarios. In the first scenario, all channels are double Rayleigh distributed. In the second
scenario, only the secondary source to relay and relay to destination channels are considered to be subject to double
Rayleigh fading whereas, channels between the secondary transmitters and the primary user are modelled by the
Rayleigh distribution. Exact and approximate expressions for the outage probability performance for all considered RS
policies and fading scenarios are presented. In addition to the analytical results, complementary computer simulated
performance evaluation results have been obtained by means of Monte Carlo simulations. The perfect match between
these two sets of results has verified the accuracy of the proposed mathematical analysis.

Equilibrium Assignments in Competitive and Cooperative Traffic Flow Routing

Part 18: Optimization in Collaborative Networks

JOINT ENERGY BEAMFORMING AND TIME ASSIGNMENT FOR COOPERATIVE WIRELESS POWERED NETWORKS

Wireless power transfer (WPT) and radio frequency (RF)-based energy har- vesting arouses a new wireless network paradigm termed as wireless powered com- munication network (WPCN), where some energy-constrained nodes are enabled to harvest energy from the RF signals transferred by other energy-sufficient nodes to support the communication operations in the network, which brings a promising approach for future energy-constrained wireless network design. In this paper, we focus on the optimal WPCN design. We consider a net- work composed of two communication groups, where the first group has sufficient power supply but no available bandwidth, and the second group has licensed band- width but very limited power to perform required information transmission. For such a system, we introduce the power and bandwidth cooperation between the two groups so that both group can accomplish their expected information delivering tasks. Multiple antennas are employed at the hybrid access point (H-AP) to en- hance both energy and information transfer efficiency and the cooperative relaying is employed to help the power-limited group to enhance its information transmission throughput. Compared with existing works, cooperative relaying, time assignment, power allocation, and energy beamforming are jointly designed in a single system. Firstly, we propose a cooperative transmission protocol for the considered system, where group 1 transmits some power to group 2 to help group 2 with information transmission and then group 2 gives some bandwidth to group 1 in return. Sec- ondly, to explore the information transmission performance limit of the system, we formulate two optimization problems to maximize the system weighted sum rate by jointly optimizing the time assignment, power allocation, and energy beamforming under two different power constraints, i.e., the fixed power constraint and the aver- age power constraint, respectively. In order to make the cooperation between the two groups meaningful and guarantee the quality of service (QoS) requirements of both groups, the minimal required data rates of the two groups are considered as constraints for the optimal system design. As both problems are non-convex and have no known solutions, we solve it by using proper variable substitutions and the semi-definite relaxation (SDR). We theoretically prove that our proposed solution method can guarantee to find the global optimal solution. Thirdly, consider that the WPCN has promising application potentials in future energy-constrained net- works, e.g., wireless sensor network (WSN), wireless body area network (WBAN) and Internet of Things (IoT), where the power consumption is very critical. We investigate the minimal power consumption optimal design for the considered co- operation WPCN. For this, we formulate an optimization problem to minimize the total consumed power by jointly optimizing the time assignment, power allocation, and energy beamforming under required data rate constraints. As the problem is also non-convex and has no known solutions, we solve it by using some variable substitutions and the SDR method. We also theoretically prove that our proposed solution method for the minimal power consumption design guarantees the global optimal solution. Extensive experimental results are provided to discuss the system performance behaviors, which provide some useful insights for future WPCN design. It shows that the average power constrained system achieves higher weighted sum rate than the fixed power constrained system. Besides, it also shows that in such a WPCN, relay should be placed closer to the multi-antenna H-AP to achieve higher weighted sum rate and consume lower total power.

Turkish Security Policymaking on Nuclear Issues: Conceptualizing Advanced Cooperative Security Strategies

Turkey is a non-nuclear member of a nuclear alliance in a region where nuclear proliferation is of particular concern. As the only North Atlantic Treaty Organization (NATO) member that has a border with the Middle East, Turkish officials argue that Turkey cannot solely rely on NATO guarantees in addressing the regional security challenges. However, Turkey has not been able to formulate a security policy that reconciles its quest for independence, its NATO membership, the bilateral relationship with the United States, and regional engagement in the Middle East. This dissertation assesses the strategic implications of Turkey’s perceptions of the U.S./NATO nuclear and conventional deterrence on nuclear issues. It explores three case studies by the process tracing of Turkish policymakers’ nuclear-related decisions on U.S. tactical nuclear weapons deployed in Europe, national air and missile defense, and Iran’s nuclear program. The study finds that the principles of Turkish security policymaking do not incorporate a fundamentally different reasoning on nuclear issues than conventional deterrence. Nuclear weapons and their delivery systems do not have a defining role in Turkish security and defense strategy. The decisions are mainly guided by non-nuclear considerations such as Alliance politics, modernization of the domestic defense industry, and regional influence. The dissertation argues that Turkey could formulate more effective and less risky security policies on nuclear issues by emphasizing the cooperative security approaches within the NATO Alliance over confrontational measures. The findings of this dissertation reveal that a major transformation of Turkish security policymaking is required to end the crisis of confidence with NATO, redefinition of the strategic partnership with the US, and a more cautious approach toward the Middle East. The dissertation argues that Turkey should promote proactive measures to reduce, contain, and counter risks before they develop into real threats, as well as contribute to developing consensual confidence-building measures to reduce uncertainty.

Le principe québécois de l'impartageabilité de la réserve des coopératives non financières: discussion critique autour du maintien ou de la suppression

La réserve générale interdite de partage entre les membres est un avoir obligatoire, impartageable tout au long de l’existence de la coopérative et sujet à la «dévolution désintéressée en cas de liquidation ou de dissolution». Cette réserve fonctionne comme un levier de soutien au développement de la coopérative et du mouvement coopératif dans son ensemble. Le principe de l’impartageabilité de la réserve est l’interdiction faite à toutes les coopératives du Québec de partager la réserve générale entre tous les membres et l’interdiction de la diminuer, notamment par l’attribution d’une ristourne tout au long de l’existence de la coopérative. En effet, l’impartageabilité de la réserve se fonde sur l’idée que la coopérative n’a pas pour but l’accumulation des capitaux afin de les répartir entre les membres, mais il s’agit de la création d’un capital collectif qui bénéficie à tous les adhérents présents et futurs. Si le concept de l’impartageabilité de la réserve interdit donc le partage de la réserve tout au long de l’existence de la coopérative, cette même interdiction prend le nom de la dévolution désintéressée de l’actif net au moment de la disparition de la coopérative. Cette dévolution désintéressée signifie l’interdiction faite à toutes les coopératives non financières de partager le solde de l’actif lors de la disparition (dissolution ou liquidation) de la coopérative à l’exception des coopératives agricoles qui peuvent décider dans ce cas, de distribuer le solde de l’actif aux membres sans qu’on sache les raisons de cette exception. Par ailleurs, l’impartageabilité de la réserve est considérée comme un simple inconvénient juridique pour les membres et a connu quelques réécritures dans les législations sur les coopératives sans qu’on connaisse vraiment les raisons de ces modifications. L’objectif de notre thèse est d’engager une discussion critique autour du questionnement central suivant : au regard du cadre juridique actuel sur les coopératives, le principe de l’impartageabilité de la réserve doit être maintenu comme tel dans la Loi sur les coopératives, ou être tout simplement supprimé, comme dans la société par actions, où il est inexistant sans que cette suppression ne porte atteinte à la notion juridique de la coopérative? Plus précisément, quel est ce cadre juridique et quels sont les motifs qui peuvent plaider en faveur du maintien ou de la suppression du principe de l’impartageabilité de la réserve? Pour répondre à cette question, cette thèse se divise en deux parties. La première partie explore le cadre juridique des coopératives non financières au Québec en comparaison avec certains concepts juridiques issus d’autres législations. Elle étudie les fondements juridiques sous-jacents à l’impartageabilité de la réserve en droit québécois des coopératives non financières. La deuxième partie réalise une discussion critique autour de l’histoire du principe de l’impartageabilité de la réserve (ch. 3), des différents arguments juridiques disponibles (ch. 4) et d’hypothèses articulées autour des effets concrets disponibles (ch. 5). Elle explore ces dimensions au soutien du maintien ou non de l’impartageabilité de la réserve de la législation actuelle sur les coopératives non financières. Bien que la recherche effectuée conduise à une réponse nuancée, l'ensemble des résultats milite plutôt en faveur du maintien du principe de l'impartageabilité de la réserve. Au préalable, l’observation des fondements juridiques des concepts sous-jacents à l’impartageabilité de la réserve en droit québécois des coopératives non financières a permis de comprendre les concepts sous-jacents à ce principe avant de répondre à la question autour de son maintien ou de sa suppression de la législation actuelle sur les coopératives. La discussion réalisée a permis de souligner l’importance d’une réalité de base assez évidente : ce principe permet de préserver la réserve, utile au développement de la coopérative et du mouvement coopératif dans son ensemble. De plus, ce principe de l’impartageabilité de la réserve s’inscrit dans le cadre de la vocation sociale de la coopérative, qui n’a pas pour but la maximisation du profit pécuniaire. L’impartageabilité de la réserve s’inscrit également dans le cadre de la cohérence du droit québécois des coopératives avec la notion de coopérative telle que définie par le mouvement coopératif québécois et l’ACI tout en répondant aux finalités historiques d’équité entre les générations et de solidarité. Enfin, même si la discussion des arguments tirés des illustrations de données comptables et de quelques entretiens réalisés avec certains membres actifs du mouvement coopératif ne permet pas de mener à toute conclusion ferme, il ressort que l’impartageabilité de la réserve ne freinerait pas la tendance à la hausse des investissements et du chiffre d’affaires des coopératives non financières. Cette interdiction constituerait même un mécanisme d’autofinancement de la coopérative et un symbole de solidarité.

Interaction and cooperative effort among scientific societies. Twelve years of COSCE

The evolution of knowledge and technology in recent decades has brought profound changes in science policy, not only in the countries but also in the supranational organizations. It has been necessary, therefore, to adapt the scientific institutions to new models in order to achieve a greater and better communication between them and the political counterparts responsible for defining the general framework of relations between science and society. The Federationon of Scientific Societies of Spain (COSCE, Confederación de Sociedades Científicas de España) was founded in October 2003 to respond to the urgent need to interact with the political institutions and foster a better orientation in the process of making decisions about the science policy. Currently COSCE consists of over 70 Spanish scientific societies and more than 40,000 scientists. During its twelve years of active life, COSCE has developed an intense work of awareness of the real situation of science in Spain by launching several initiatives (some of which have joined other organizations) or by joining initiatives proposed from other groups related to science both at the Spanish level and at the European and non-European scenarios.

Le principe québécois de l'impartageabilité de la réserve des coopératives non financières: discussion critique autour du maintien ou de la suppression

La réserve générale interdite de partage entre les membres est un avoir obligatoire, impartageable tout au long de l’existence de la coopérative et sujet à la «dévolution désintéressée en cas de liquidation ou de dissolution». Cette réserve fonctionne comme un levier de soutien au développement de la coopérative et du mouvement coopératif dans son ensemble. Le principe de l’impartageabilité de la réserve est l’interdiction faite à toutes les coopératives du Québec de partager la réserve générale entre tous les membres et l’interdiction de la diminuer, notamment par l’attribution d’une ristourne tout au long de l’existence de la coopérative. En effet, l’impartageabilité de la réserve se fonde sur l’idée que la coopérative n’a pas pour but l’accumulation des capitaux afin de les répartir entre les membres, mais il s’agit de la création d’un capital collectif qui bénéficie à tous les adhérents présents et futurs. Si le concept de l’impartageabilité de la réserve interdit donc le partage de la réserve tout au long de l’existence de la coopérative, cette même interdiction prend le nom de la dévolution désintéressée de l’actif net au moment de la disparition de la coopérative. Cette dévolution désintéressée signifie l’interdiction faite à toutes les coopératives non financières de partager le solde de l’actif lors de la disparition (dissolution ou liquidation) de la coopérative à l’exception des coopératives agricoles qui peuvent décider dans ce cas, de distribuer le solde de l’actif aux membres sans qu’on sache les raisons de cette exception. Par ailleurs, l’impartageabilité de la réserve est considérée comme un simple inconvénient juridique pour les membres et a connu quelques réécritures dans les législations sur les coopératives sans qu’on connaisse vraiment les raisons de ces modifications. L’objectif de notre thèse est d’engager une discussion critique autour du questionnement central suivant : au regard du cadre juridique actuel sur les coopératives, le principe de l’impartageabilité de la réserve doit être maintenu comme tel dans la Loi sur les coopératives, ou être tout simplement supprimé, comme dans la société par actions, où il est inexistant sans que cette suppression ne porte atteinte à la notion juridique de la coopérative? Plus précisément, quel est ce cadre juridique et quels sont les motifs qui peuvent plaider en faveur du maintien ou de la suppression du principe de l’impartageabilité de la réserve? Pour répondre à cette question, cette thèse se divise en deux parties. La première partie explore le cadre juridique des coopératives non financières au Québec en comparaison avec certains concepts juridiques issus d’autres législations. Elle étudie les fondements juridiques sous-jacents à l’impartageabilité de la réserve en droit québécois des coopératives non financières. La deuxième partie réalise une discussion critique autour de l’histoire du principe de l’impartageabilité de la réserve (ch. 3), des différents arguments juridiques disponibles (ch. 4) et d’hypothèses articulées autour des effets concrets disponibles (ch. 5). Elle explore ces dimensions au soutien du maintien ou non de l’impartageabilité de la réserve de la législation actuelle sur les coopératives non financières. Bien que la recherche effectuée conduise à une réponse nuancée, l'ensemble des résultats milite plutôt en faveur du maintien du principe de l'impartageabilité de la réserve. Au préalable, l’observation des fondements juridiques des concepts sous-jacents à l’impartageabilité de la réserve en droit québécois des coopératives non financières a permis de comprendre les concepts sous-jacents à ce principe avant de répondre à la question autour de son maintien ou de sa suppression de la législation actuelle sur les coopératives. La discussion réalisée a permis de souligner l’importance d’une réalité de base assez évidente : ce principe permet de préserver la réserve, utile au développement de la coopérative et du mouvement coopératif dans son ensemble. De plus, ce principe de l’impartageabilité de la réserve s’inscrit dans le cadre de la vocation sociale de la coopérative, qui n’a pas pour but la maximisation du profit pécuniaire. L’impartageabilité de la réserve s’inscrit également dans le cadre de la cohérence du droit québécois des coopératives avec la notion de coopérative telle que définie par le mouvement coopératif québécois et l’ACI tout en répondant aux finalités historiques d’équité entre les générations et de solidarité. Enfin, même si la discussion des arguments tirés des illustrations de données comptables et de quelques entretiens réalisés avec certains membres actifs du mouvement coopératif ne permet pas de mener à toute conclusion ferme, il ressort que l’impartageabilité de la réserve ne freinerait pas la tendance à la hausse des investissements et du chiffre d’affaires des coopératives non financières. Cette interdiction constituerait même un mécanisme d’autofinancement de la coopérative et un symbole de solidarité.

Query routing in cooperative semi-structured peer-to-peer information retrieval networks

Conventional web search engines are centralised in that a single entity crawls and indexes the documents selected for future retrieval, and the relevance models used to determine which documents are relevant to a given user query. As a result, these search engines suffer from several technical drawbacks such as handling scale, timeliness and reliability, in addition to ethical concerns such as commercial manipulation and information censorship. Alleviating the need to rely entirely on a single entity, Peer-to-Peer (P2P) Information Retrieval (IR) has been proposed as a solution, as it distributes the functional components of a web search engine – from crawling and indexing documents, to query processing – across the network of users (or, peers) who use the search engine. This strategy for constructing an IR system poses several efficiency and effectiveness challenges which have been identified in past work. Accordingly, this thesis makes several contributions towards advancing the state of the art in P2P-IR effectiveness by improving the query processing and relevance scoring aspects of a P2P web search. Federated search systems are a form of distributed information retrieval model that route the user’s information need, formulated as a query, to distributed resources and merge the retrieved result lists into a final list. P2P-IR networks are one form of federated search in routing queries and merging result among participating peers. The query is propagated through disseminated nodes to hit the peers that are most likely to contain relevant documents, then the retrieved result lists are merged at different points along the path from the relevant peers to the query initializer (or namely, customer). However, query routing in P2P-IR networks is considered as one of the major challenges and critical part in P2P-IR networks; as the relevant peers might be lost in low-quality peer selection while executing the query routing, and inevitably lead to less effective retrieval results. This motivates this thesis to study and propose query routing techniques to improve retrieval quality in such networks. Cluster-based semi-structured P2P-IR networks exploit the cluster hypothesis to organise the peers into similar semantic clusters where each such semantic cluster is managed by super-peers. In this thesis, I construct three semi-structured P2P-IR models and examine their retrieval effectiveness. I also leverage the cluster centroids at the super-peer level as content representations gathered from cooperative peers to propose a query routing approach called Inverted PeerCluster Index (IPI) that simulates the conventional inverted index of the centralised corpus to organise the statistics of peers’ terms. The results show a competitive retrieval quality in comparison to baseline approaches. Furthermore, I study the applicability of using the conventional Information Retrieval models as peer selection approaches where each peer can be considered as a big document of documents. The experimental evaluation shows comparative and significant results and explains that document retrieval methods are very effective for peer selection that brings back the analogy between documents and peers. Additionally, Learning to Rank (LtR) algorithms are exploited to build a learned classifier for peer ranking at the super-peer level. The experiments show significant results with state-of-the-art resource selection methods and competitive results to corresponding classification-based approaches. Finally, I propose reputation-based query routing approaches that exploit the idea of providing feedback on a specific item in the social community networks and manage it for future decision-making. The system monitors users’ behaviours when they click or download documents from the final ranked list as implicit feedback and mines the given information to build a reputation-based data structure. The data structure is used to score peers and then rank them for query routing. I conduct a set of experiments to cover various scenarios including noisy feedback information (i.e, providing positive feedback on non-relevant documents) to examine the robustness of reputation-based approaches. The empirical evaluation shows significant results in almost all measurement metrics with approximate improvement more than 56% compared to baseline approaches. Thus, based on the results, if one were to choose one technique, reputation-based approaches are clearly the natural choices which also can be deployed on any P2P network.

Studio, Progettazione e Sviluppo di Applicazioni di Realtà Mista Cooperative

Le esperienze cooperative in realtà mista. Che cosa sono? Quali sono gli scopi dietro il loro sviluppo? Che cosa aspetta uno sviluppatore che si avvicina a questi sistemi? Questa tesi cerca di rispondere a queste domande ponendo sotto esame diverse tecnologie di collocazione molto recente, analizzando un progetto preso come caso di studio e implementato tramite diversi strumenti. Al giorno d’oggi, la sfera della realtà mista/realtà aumentata si sta espandendo sempre di più, arrivando a sfiorare mondi che prima risultavano totalmente scollegati. Il mondo dello sviluppo in ambito gaming è entrato infine in questo panorama grazie alle tante similarità con certi tipi di applicazioni MR. Uno degli strumenti più utilizzati in questo ambito è Unity, un motore grafico utilizzato per creare videogiochi e non solo: in questo progetto si sfrutterà questo ambiente di sviluppo per realizzare una semplice applicazione in realtà mista cooperativa, che permetta quindi l’accesso a più utenti contemporaneamente e la loro interazione. Per farlo, si valuteranno diverse opzioni, in particolare due, Netcode for GameObjects e Photon PUN, provenienti da due ambienti diversi ma entrambe strettamente legate a Unity, cercando di ottenere lo stesso risultato ma con due strade diverse come base per un confronto. Basteranno queste tecnologie o ci vuole ancora altro per la realtà mista? Questo studio trova una base matura e pronta a uscire dal suo guscio? Oppure c’è ancora tanta strada da fare? Sulla base di questo verrà tenuto il confronto, cercando una risposta generale ma concreta. Questa tesi si dividerà in due parti: la parte introduttiva, che fornirà tutti i concetti sulla realtà mista necessari e un panorama sull’ambiente MR in generale. La seconda, invece, servirà a illustrare quali sono le sfide di uno sviluppo in questo mondo, usando un progetto applicativo come soluzione a queste sfide o almeno ad una loro parte.