Quantized Dissensus in Networks of Agents subject to Death and Duplication

Dissensus is a modeling framework for networks of dynamic agents in competition for scarce resources. Originally inspired by biological cells behaviors, it fits also marketing, finance and many other application areas. Competition is often unstable in the sense that strong agents, those having access to large resources, gain more and more resources at the expense of weak agents. Thus, strong agents duplicate when reaching a critical amount of resources, whereas weak agents die when loosing all their resources. To capture all these phenomena we introduce systems with a discrete time gossip and unstable state dynamics interrupted by discrete events affecting the network topology. Invariancy of states and topologies and network connectivity are explored

A Message Passing Strategy for Decentralized Connectivity Maintenance in Agent Removal

In a multi-agent system, agents coordinate to achieve global tasks through local communications. Coordination usually requires sufficient information flow, which is usually depicted by the connectivity of the communication network. In a networked system, removal of some agents may cause a disconnection. In order to maintain connectivity in agent removal, one can design a robust network topology that tolerates a finite number of agent losses, and/or develop a control strategy that recovers connectivity. This paper proposes a decentralized control scheme based on a sequence of replacements, each of which occurs between an agent and one of its immediate neighbors. The replacements always end with an agent, whose relocation does not cause a disconnection. We show that such an agent can be reached by a local rule utilizing only some local information available in agents' immediate neighborhoods. As such, the proposed message passing strategy guarantees the connectivity maintenance in arbitrary agent removal. Furthermore, we significantly improve the optimality of the proposed scheme by incorporating $\delta$-criticality (i.e. the criticality of an agent in its $\delta$-neighborhood).Comment: 9 pages, 9 figure

Behaviors of Networks with Antagonistic Interactions and Switching Topologies

In this paper, we study the discrete-time consensus problem over networks with antagonistic and cooperative interactions. A cooperative interaction between two nodes takes place when one node receives the true state of the other while an antagonistic interaction happens when the former receives the opposite of the true state of the latter. We adopt a quite general model where the node communications can be either unidirectional or bidirectional, the network topology graph may vary over time, and the cooperative or antagonistic relations can be time-varying. It is proven that, the limits of all the node states exist, and the absolute values of the node states reach consensus if the switching interaction graph is uniformly jointly strongly connected for unidirectional topologies, or infinitely jointly connected for bidirectional topologies. These results are independent of the switching of the interaction relations. We construct a counterexample to indicate a rather surprising fact that quasi-strong connectivity of the interaction graph, i.e., the graph contains a directed spanning tree, is not sufficient to guarantee the consensus in absolute values even under fixed topologies. Based on these results, we also propose sufficient conditions for bipartite consensus to be achieved over the network with joint connectivity. Finally, simulation results using a discrete-time Kuramoto model are given to illustrate the convergence results showing that the proposed framework is applicable to a class of networks with general nonlinear dynamics

Formulation of control strategies for requirement definition of multi-agent surveillance systems

In a multi-agent system (MAS), the overall performance is greatly influenced by both the design and the control of the agents. The physical design determines the agent capabilities, and the control strategies drive the agents to pursue their objectives using the available capabilities. The objective of this thesis is to incorporate control strategies in the early conceptual design of an MAS. As such, this thesis proposes a methodology that mainly explores the interdependency between the design variables of the agents and the control strategies used by the agents. The output of the proposed methodology, i.e. the interdependency between the design variables and the control strategies, can be utilized in the requirement analysis as well as in the later design stages to optimize the overall system through some higher fidelity analyses. In this thesis, the proposed methodology is applied to a persistent multi-UAV surveillance problem, whose objective is to increase the situational awareness of a base that receives some instantaneous monitoring information from a group of UAVs. Each UAV has a limited energy capacity and a limited communication range. Accordingly, the connectivity of the communication network becomes essential for the information flow from the UAVs to the base. In long-run missions, the UAVs need to return to the base for refueling with certain frequencies depending on their endurance. Whenever a UAV leaves the surveillance area, the remaining UAVs may need relocation to mitigate the impact of its absence. In the control part of this thesis, a set of energy-aware control strategies are developed for efficient multi-UAV surveillance operations. To this end, this thesis first proposes a decentralized strategy to recover the connectivity of the communication network. Second, it presents two return policies for UAVs to achieve energy-aware persistent surveillance. In the design part of this thesis, a design space exploration is performed to investigate the overall performance by varying a set of design variables and the candidate control strategies. Overall, it is shown that a control strategy used by an MAS affects the influence of the design variables on the mission performance. Furthermore, the proposed methodology identifies the preferable pairs of design variables and control strategies through low fidelity analysis in the early design stages.Ph.D

Proliferate! A techno-social history of the internet meme, from print to platforms

Internet memes are often understood as artefacts that have communicative utility within online discourses replete with legible aesthetic and affective attributes. Accordingly, valuable scholarly work has been done to understand how internet memes function as and within online social interactions. However, less attention has been paid to the ways in which the assemblage of technologies that comprise the internet mediate the social practices that produce internet memes. This thesis attends to this lesser-studied area by acknowledging that it is from the internet, as a particular but evolving assemblage of technologies, that the internet meme emerges. In so doing, I develop an analytic framework which recovers technics as co-constitutive of the social practices that bring forth internet memes. Thus, the techno-social of this thesis’ title references the supposition that internet memes are contingent on the irreducible relationship between the technics of the internet and the associated social practices they mediate. This claim is advanced by historicising the internet meme. In the first half of this thesis, I identify a selection of precursor “memes” that emerged from antecedent techno-social arrangements present in mid-to-late 20th century Anglo / U.S.-centric discourses. These accounts are mobilised to better clarify the specificity of the internet in mediating the techno-social practices that produce internet memes – a dynamic explored in the latter chapters of the thesis. A techno-social history of the meme therefore asserts that memes – internet or otherwise – have historically emerged and will continue to emerge across myriad techno-social milieu; with the historical framing functioning as an analytic device that draws into relief the ways in which the internet makes the internet meme distinct. Such an approach relies on a working definition of the meme, internet or otherwise. This is no simple task. As is recounted in this thesis’ introduction, the concept of “the meme” has been a contested one since the term’s emergence. Drawing on the work of Limor Shifman in particular, I assert that memes can only be differentiated from other forms of cultural production in the specific ways they proliferate – via social practices of reproduction and remix animated by the use of technical media. Notably, the recognition of proliferation as the meme’s defining feature undergirds this thesis’ analytical framing, since proliferation as a social practice, and the aesthetic and affective attributes of the memes that emerge, must be realised in ways contingent on technical affordances. The internet meme then, is recognisable as such since it proliferates, and is rendered distinct through being proliferated on the internet. Having provided terms of definition, Chapter One moves to historicise the proliferating meme. In this section, the manipulation of photographic imagery relating to the Kennedy Assassination – by professional media, governmental bodies, and private citizen researchers – is reconsidered as a form of meme. Articulated as such, this chapter goes on to detail the ways in which the aesthetics and utilities of the Kennedy Assassination “meme” were realised in ways contingent on the techno-social conditions from which it emerged. Chapter Two develops this perspective further in assessing the production of mid-to-late 20th century alt-media as a form of memetic social practice; afforded by the appropriation of reprographic technologies, which in turn supplied the artefactual output with distinct forms and functions, and cultural significances. Having made the case for mobilising a techno-social history of the meme in the preceding sections, Chapter Three moves this work “online”, and offers an account of how the early web of the ’90’s and ‘00’s brought forth its own meme forms, notably the spread of web-based urban legends. Chapter Four then turns to address examples of what might be widely understood as internet memes proper - the Image Macro and GIF formats – and accounts for the ways in which the social usage of the assemblage of digital media technologies that comprise the internet gave rise to and proliferated these meme forms. Finally, Chapter Five will reflexively consider what the framework established in the prior chapters reveals about the contemporaneous internet meme – a meme form that emerges from a platformised techno social milieu – a milieu I’ll argue is characterised by financialised media ubiquity. The framework developed in this thesis provides a lens not only for studying the distinct forms and functions of meme forms, with particular attention paid to the internet meme, but also accounts for the inevitable future evolution of memes as techno-social arrays continue to reconfigur

A MUSICAL ANALYSIS OF THE PEOPLE'S MICROPHONE: VOICES AND ECHOES IN PROTEST AND SOUND ART AND OCCUPATION 1 FOR STRING QUARTET

The People's Microphone technique, first employed by Occupy Wall Street in the 2011 occupation of Zuccotti Park, is a mode of political speech drawing on the fundamental linguistic/musical principle of imitation. By analyzing musical parameters of the tones of voice in instances of the People's Microphone in protest, and secondly by adapting the method to analyze how the People's Microphone is used in an artwork by Brandon LaBelle, I lay the speculative groundwork for a transversal theory dealing with the political influence of musical sound. This theory is extended to Angela Davis, a piece in Peter Ablinger's Voices and Piano series of compositions for piano and audio recording in which the piano exactly imitates the intonations of the voice in different ways. The arousal of cognitive dissonance through vocal inflection in interaction with contexts of perception is the common thread through several examples that allows a holistic theoretical approach across the domains of sound, art and politics. The argument demonstrates how the intrinsic parameters of all vocal sound are both an ever-present aesthetic and political force. The second part of the dissertation is an experimental composition for string quartet wherein unison transformation with smooth as opposed to striated movement through the continuum of pitch and rhythmic space (characteristics abstracted from unison speech) provide further detailed research into effects of consonance and dissonance, both tonal and cognitive