Station Keeping through Beacon-referenced Cyclic Pursuit

This paper investigates a modification of cyclic constant bearing (CB) pursuit in a multi-agent system in which each agent pays attention to a neighbor and a beacon. The problem admits shape equilibria with collective circling about the beacon, with the circling radius and angular separation of agents determined by choice of parameters in the feedback law. Stability of circling shape equilibria is shown for a 2-agent system, and the results are demonstrated on a collective of mobile robots tracked by a motion capture system

Beacon-referenced Mutual Pursuit in Three Dimensions

Motivated by station-keeping applications in various unmanned settings, this paper introduces a steering control law for a pair of agents operating in the vicinity of a fixed beacon in a three-dimensional environment. This feedback law is a modification of the previously studied three-dimensional constant bearing (CB) pursuit law, in the sense that it incorporates an additional term to allocate attention to the beacon. We investigate the behavior of the closed-loop dynamics for a two agent mutual pursuit system in which each agent employs the beacon-referenced CB pursuit law with regards to the other agent and a stationary beacon. Under certain assumptions on the associated control parameters, we demonstrate that this problem admits circling equilibria wherein the agents move on circular orbits with a common radius, in planes perpendicular to a common axis passing through the beacon. As the common radius and distances from the beacon are determined by choice of parameters in the feedback law, this approach provides a means to engineer desired formations in a three-dimensional setting

How does regulation affect innovation and technology change in the water sector in England and Wales?

This thesis examines the role of regulation in technological change in the water sector in England and Wales. Based on a combination of Social-Ecological Systems (SES) theory and the Multi-Level Perspective on technological transitions a Comparative Information-Graded Approach (CIGA) is developed in Part 1. As part of the CIGA, a series of tools is used for characterizing and evaluating the relationship between regulation and technology. In Part 2, the CIGA is applied to characterize the relationship between regulation and water innovation in England and Wales based on official publications, Environment Agency data, and interviews. In particular, 7 mechanisms are identified by which regulation affects innovation and 5 issues of trust negatively interact with innovation. As trust is established through these mechanisms, opportunities for innovation are at times sacrificed. Part 3 develops and analyses a set of models based on findings in Part 2. Dynamical systems and fictitious play analysis of a trustee game model of regulation exhibits cyclicality providing an explanation for observed cycles which create an inconsistent drive for innovation. Trustee and coordination models are evaluated in Chapter 7 highlighting how most tools struggle with the issue of technological lock-in. Chapter 8 develops a model of two innovators and a public good water technology over time, showing the role foresight plays in this context as well as the disincentive to develop it. Taken together, the CIGA characterization and modelling work provide a series of recommendations and insights into how the system of regulation affects technology change.Open Acces

Reconstruction, Analysis and Synthesis of Collective Motion

As collective motion plays a crucial role in modern day robotics and engineering, it seems appealing to seek inspiration from nature, which abounds with examples of collective motion (starling flocks, fish schools etc.). This approach towards understanding and reverse-engineering a particular aspect of nature forms the foundation of this dissertation, and its main contribution is threefold. First we identify the importance of appropriate algorithms to extract parameters of motion from sampled observations of the trajectory, and then by assuming an appropriate generative model we turn this into a regularized inversion problem with the regularization term imposing smoothness of the reconstructed trajectory. First we assume a linear triple-integrator model, and by penalizing high values of the jerk path integral we reconstruct the trajectory through an analytical approach. Alternatively, the evolution of a trajectory can be governed by natural Frenet frame equations. Inadequacy of integrability theory for nonlinear systems poses the utmost challenge in having an analytic solution, and forces us to adopt a numerical optimization approach. However, by noting the fact that the underlying dynamics defines a left invariant vector field on a Lie group, we develop a framework based on Pontryagin's maximum principle. This approach toward data smoothing yields a semi-analytic solution. Equipped with appropriate algorithms for trajectory reconstruction we analyze flight data for biological motions, and this marks the second contribution of this dissertation. By analyzing the flight data of big brown bats in two different settings (chasing a free-flying praying mantis and competing with a conspecific to catch a tethered mealworm), we provide evidence to show the presence of a context specific switch in flight strategy. Moreover, our approach provides a way to estimate the behavioral latency associated with these foraging behaviors. On the other hand, we have also analyzed the flight data of European starling flocks, and it can be concluded from our analysis that the flock-averaged coherence (the average cosine of the angle between the velocities of a focal bird and its neighborhood center of mass, averaged over the entire flock) gets maximized by considering 5-7 nearest neighbors. The analysis also sheds some light into the underlying feedback mechanism for steering control. The third and final contribution of this dissertation lies in the domain of control law synthesis. Drawing inspiration from coherent movement of starling flocks, we introduce a strategy (Topological Velocity Alignment) for collective motion, wherein each agent aligns its velocity along the direction of motion of its neighborhood center of mass. A feedback law has also been proposed for achieving this strategy, and we have analyzed two special cases (two-body system; and an N-body system with cyclic interaction) to show effectiveness of our proposed feedback law. It has been observed through numerical simulation and robotic implementation that this approach towards collective motion can give rise to a splitting behavior

Nanoorthogonal Surface Modifications of Gold Nanoparticles and Nanoclusters through Strain-Promoted Cycloaddition Chemistry

This thesis explores the preparation of thiolated gold nanoparticles (AuNPs) and thiolated gold nanoclusters (AuNCs) capable of undergoing post-assembly surface modifications using two common “bioorthogonal” click reactions: the strain-promoted alkyne-azide cycloaddition (SPAAC) reaction (which occurs between a strained-alkyne and an azide) and the strain-promoted alkyne-nitrone cycloaddition (SPANC) reaction (which occurs between a strained-alkyne and a nitrone). Due to their rapid and modifiable reaction kinetics, high chemoselectivity, and stability of the reactive partners, these reactions were originally designed to tether functional substrates to biologically sensitive biomolecules, without altering their structure or perturb the biologically sensitive environments in which they operate in. The research presented herein explores using the SPAAC and SPANC reactions as “nanoorthogonal” click reactions, translating their advantageous characteristics towards surface modifications of thiolated AuNPs and AuNCs in an efficient and straightforward manner without perturbing their chemically sensitive structures. Chapter 2 describes the development of a reactive AuNP platform with an aliphatic strained-alkyne (specifically, bicyclo[6.1.0]nonyne (BCN)) tethered to its surface. This platform could undergo both interfacial SPAAC (I-SPAAC) and interfacial SPANC (I-SPANC), whose reaction kinetics could be tuned through structural alterations to the complementary azide/nitrone dipolar species, respectively. When highly electron-deficient dipolar species were used, rapid surface modifications could be accomplished. Such predictable alterations to the kinetic profiles of I-SPAAC and I-SPANC allows exclusive reactivity with one highly reactive dipolar species in the presence of a less reactive dipolar species, which altogether provides an efficient and versatile route towards derivatizing AuNP surfaces. To further expand the scope of such rapid modifications of AuNP surfaces, Chapter 3 explores the development of a nitrone-terminated AuNP platform, in which the surface nitrone dipolar species are delocalized into highly electron deficient pyridinium groups. In a prototype kinetic study, nitrones with pyridinium groups on the Nα of the nitrones exhibited rapid reaction kinetics with BCN, whose reaction kinetics could be altered through modifications of the Cα substituents of the nitrone. Unfortunately, due to the high reactivity of the pyridinium-functionalized nitrone group, attempts to incorporate this rapidly reactive moiety to the AuNP surface was not successful due to the synthetic incompatibilities between pyridinium-functionalized nitrones and thiols. However, the development of such rapid SPANC chemistry serves as a promising tool for modifications of other nanomaterial systems in which thiols are not present. Chapter 4 describes the first example of an azide-modified AuNC system (specifically, the [Au25(SR)18]-1 system) that could undergo post-assembly cluster-surface SPAAC (CS-SPAAC) chemistry with complementary strained-alkynes. The molecular structure of this azide-modified platform (specifically [Au25(SCH2CH2-p-C6H4-N3)18]-1 with p-azidophenylethanethiolate as the surface ligand) is reported. Whereas larger AuNP systems tend to be more rigid, the structures and integrity of smaller AuNC systems are more chemically sensitive, and the ability to conduct CS-SPAAC in a nanoorthogonal manner without altering the internal structure represents an exciting new paradigm towards AuNC surface modifications. Chapter 5 explores how the reactivity, structure and physical properties of azide-modified [Au25(SR)18]-1 platforms are affected by changing the regioisomeric form of the azide-modified surface ligands. Two isomeric forms of [Au25(SCH2CH2-p-C6H4-N3)18]-1 were developed: [Au25(SCH2CH2-m-C6H4-N3)18]-1 and [Au25(SCH2CH2-o-C6H4-N3)18]-1. The molecular structures of the neutrally charged forms of these three isomers are reported. It was found that although the physical properties appeared to be largely unaffected, the structure and reactivity of these azide-modified platforms appear to be dependent on the regioisomeric form of the azide-modified surface ligand. Chapter 6 describes the first example of a ferrocene-modified [Au25(SR)18]-1 system, which could be accomplished through a CS-SPAAC reaction between the azide-modified [Au25(SCH2CH2-p-C6H4-N3)18]-1 platform and BCN-terminated ferrocene, which highlights the true power of conducting CS-SPAAC chemistry on the surface of [Au25(SR)18]-1 frameworks to incorporate large, functional substrates. In total, this work describes and explores innovative methodologies that can be used to conduct chemical modifications of AuNP and AuNC surfaces using SPAAC and SPANC, in an efficient and nanoorthogonal manner without altering the parent structures. Using such versatile and effective strategies, it will be possible to develop functional variants of these popular nanomaterial systems more easily for application-based research

A cumulative index to Aeronautical Engineering: A special bibliography

This publication is a cumulative index to the abstracts contained in NASA SP-7037 (80) through NASA SP-7037 (91) of Aeronautical Engineering: A Special Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics (AIAA) and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

Using MapReduce Streaming for Distributed Life Simulation on the Cloud

Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conway’s life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MR’s applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithms’ performance on Amazon’s Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp

The conduct of war and the notion of victory: a theory and definition of victory

Clausewitz described military victory as a condition where the enemy‘s ability to enter battle, resist or resume hostilities is destroyed. The concept summarises the paradigm of success that preceded Clausewitz and survived through much of the 20th century. Despite increasingly paradoxical outcomes in the last century and the current one, military planners, strategists and statesmen sought answers for failures in different places, only a few questioned the validity of the notion of victory that Clausewitz had so veritably summarised. The fundamental question that begs an answer is ‗what is victory?‘ The rapid transformation in society and international culture has brought with it changes in geo-political and geo-economic relationships as well as warfare. While the traditional linkages between war and politics remain, the mechanisms driving these have altered. In less than absolute wars, it is the wider bargain and the stakes in that bargain that make the ‗enemy do our will‘ and not purely an inability to enter battle, resist or resume hostilities. The new complexities surrounding war and diplomacy necessitate an organising theory to make better sense of policy and action. This research provides one such theory. War is ultimately a violent clash of societies and its character a reflection of opposing cultures, history and experiences. An external dimension to strategy is thus always at work even if not fully recognised; as is often the case. Such un-factored influences create a sort of volatility in victory and defeat adding new challenges while offering opportunities at the same time. Similarly, diplomacy, which invariably precedes and succeeds coercive or compelling use of violence, too is fettered by such external influences. A bivariate approach that triangulates desired ends with the opposing notions of success and perception of defeat is argued. The theory presented encapsulates traditional precepts, adds new ones and simplifies the complexities that have come to surround victory in contemporary times. Offered here are some valuable ingredient to flavour any strategic recipe, not just war and conflict. The eternal challenge of calibrating means and ends needed more systematic awareness of functional and dominant domains of victory which is arguably possible through application of simple principles. The theory potentially allows for a more focused, proportionate, efficient and productive use of power. It is hoped that strategists and analysts alike, would find here new concepts and tools for use in praxis, perspective planning and retrospective analyses