On distributed ledger technology for the internet of things: design and applications

Distributed ledger technology (DLT) can used to store information in such a way that no individual or organisation can compromise its veracity, contrary to a traditional centralised ledger. This nascent technology has received a great deal of attention from both researchers and practitioners in recent years due to the vast array of open questions related to its design and the assortment novel applications it unlocks. In this thesis, we are especially interested in the design of DLTs suitable for application in the domain of the internet of things (IoT), where factors such as efficiency, performance and scalability are of paramount importance. This work confronts the challenges of designing IoT-oriented distributed ledgers through analysis of ledger properties, development of design tools and the design of a number of core protocol components. We begin by introducing a class of DLTs whose data structures consist of directed acyclic graphs (DAGs) and which possess properties that make them particularly well suited to IoT applications. With a focus on the DAG structure, we then present analysis through mathematical modelling and simulations which provides new insights to the properties of this class of ledgers and allows us to propose novel security enhancements. Next, we shift our focus away from the DAG structure itself to another open problem for DAG-based distributed ledgers, that of access control. Specifically, we present a networking approach which removes the need for an expensive and inefficient mechanism known as Proof of Work, solving an open problem for IoT-oriented distributed ledgers. We then draw upon our analysis of the DAG structure to integrate and test our new access control with other core components of the DLT. Finally, we present a mechanism for orchestrating the interaction between users of a DLT and its operators, seeking to improves the usability of DLTs for IoT applications. In the appendix, we present two projects also carried out during this PhD which showcase applications of this technology in the IoT domain.Open Acces

Effect of Ultrasonication on the Physicochemical Properties of Sorghum Kafirin and Evaluation of its Anti-inflammatory Properties \u3ci\u3eIn Vitro\u3c/i\u3e

Sorghum is one of the hardiest, most drought resistent cereal grains known to exist, providing the bulk of nutritional content for many semi-arid regions and developing countries throughout Africa and southwestern Asia. It contains dense nutritional value, but due to inhibition factors within the grain, much of these nutrients are indigestible. Access to these nutrients, which have shown to contain high contents of bioactive molecules linked to the decrease of prevalence of chronic disease, must then be facilitated before consumption. In sorghum, these molecules could include complex carbohydrates, proteins and polyphenols. The overall objective of this study was to determine the effect of ultrasonication on kafirin’s physicochemical properties and evaluate its effects on inflammatory response in vitro. Ultrasonication is a processing tool causing self-collapsing micro-cavitations disrupting structure and altering function. Kafirin was extracted and purified from sorghum flour using differential solubility extraction methods, concentrated and lyophilized. The effects of ultrasonication on the secondary structure of kafirin and its stability after ultrasonication against pepsinpancreatin hydrolysis were measured. Ultrasonication altered the secondary structure of kafirin, increased its solubility and improved its antioxidant capacity. Kafirin was also evaluated for its ability to halt the production of pro-inflammatory cytokines through inhibition of reactive oxygen species production in THP-1 human macrophages primed with lipopolysaccharides (LPS). An association exists between overexpressed inflammatory response from aberrant activation of the inflammatory pathway and chronic diseases. LPS-treated THP-1 macrophages were treated with 50 and 100 μg (microgram) kafirin/mL. The treatment of kafirin led to inhibition of the production of intracellular reactive oxygen species (ROS), disrupting the inflammatory signaling cascade and reducing the production of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α. These results showed that kafirin can inactivate the inflammatory response pathway by inhibiting intracellular ROS production. This study is the first to report on ultrasonication as a viable option for increasing the digestibility of kafirin as well as kafirin’s potential as chemopreventive agent against chronic disease associated with aberrant inflammation

Fabrication of 3D Conjugated Polymer Structures via Vat Polymerization Additive Manufacturing

Conjugated polymers are a class of electromechanically active materials that can produce motion in response to an electric potential. This motion can be harnessed to perform mechanical work, and therefore these materials are particularly well suited for use as sensors and actuators in microelectromechanical systems. Conventional methods to fabricate conjugated polymer actuators result in planar morphologies that limit fabricated devices to simplistic linear or bending actuation modes. To overcome this limitation, this work develops a conjugated polymer formulation and associated additive manufacturing method capable of realizing three-dimensional conductive polymer structures. A light-based additive manufacturing technique known as vat polymerization is employed due to its ability to fabricate complex microscale features. A specially-formulated photosensitive polypyrrole resin was optimized for the production of microscale 3D structures. The transduction properties of the photosensitive polymer formulation were characterized to evaluate the material\u27s application in mechanical sensing and actuation technologies

A Multi-Objective Linear Program Model to Test Hub-and-Spoke Networks as a Potential Air Force Deployment Alternative

The purpose of this research is to develop a multiple-objective mixed-integer linear programming model that determines the feasibility of a new deployment paradigm, which offers greater flexibility to home station and deployed location civil engineers (CE) by applying hub-and-spoke networking. The research covers the histories of CE and Air and Space Expeditionary Force (AEF), current CE deployment needs, multiple-objective decision analysis, hub-and-spoke networking, and organizational behavior benefits of the new paradigm. The methodology section provides details on each objective, explains the model, defines weights, and explains the objective function’s calculation. Next, an analysis of the model’s resulting scenarios helps determine the appropriate parameters. Research conclusions and recommendations for potential future study are provided. Some of the new paradigm’s benefits include the consolidation of coordination, training, equipment, travel, and other mobility related activities. The paradigm provides home station and deployed CE leaders with greater control over the mobilization of their resources. This control should help to reduce fluctuations in home station manpower levels, and deployment to the same location should make the process easier for everyone involved. A final added benefit to regional clustering is that it opens the door to improved networking between active duty and guard/reserve components

Mechanical Engineering Design Project report: Enabler control systems

The Controls Group was assigned the responsibility for designing the Enabler's control system. The requirement for the design was that the control system must provide a simple user interface to control the boom articulation joints, chassis articulation joints, and the wheel drive. The system required controlling hydraulic motors on the Enabler by implementing 8-bit microprocessor boards. In addition, feedback to evaluate positions and velocities must be interfaced to provide the operator with confirmation as well as control