A low-complexity flight controller for Unmanned Aircraft Systems with constrained control allocation

In this paper, we propose a framework for joint allocation and constrained control design of flight controllers for Unmanned Aircraft Systems (UAS). The actuator configuration is used to map actuator constraint set into the space of the aircraft generalised forces. By constraining the demanded generalised forces, we ensure that the allocation problem is always feasible; and therefore, it can be solved without constraints. This leads to an allocation problem that does not require on-line numerical optimisation. Furthermore, since the controller handles the constraints, and there is no need to implement heuristics to inform the controller about actuator saturation. The latter is fundamental for avoiding Pilot Induced Oscillations (PIO) in remotely operated UAS due to the rate limit on the aircraft control surfaces.

Joint motion control and control allocation design for UAS flight control systems

As Unmanned Aircraft Systems (UAS) grow in complexity, and their level of autonomy increases|moving away from the concept of a remotely piloted systems and more towards autonomous systems|there is a need to further improve reliability and tolerance to faults. The traditional way to accommodate actuator faults is by using standard control allocation techniques as part of the flight control system. The allocation problem in the presence of faults often requires adding constraints that quantify the maximum capacity of the actuators. This in turn requires on-line numerical optimisation. In this paper, we propose a framework for joint allocation and constrained control scheme via vector input scaling. The actuator configuration is used to map actuator constraints into the space of the aircraft generalised forces, which are the magnitudes demanded by the light controller. Then by constraining the output of controller, we ensure that the allocation function always receive feasible demands. With the proposed framework, the allocation problem does not require numerical optimisation, and since the controller handles the constraints, there is not need to implement heuristics to inform the controller about actuator saturation.

Structured contract strategies for capital and operations expenditure projects in the oil and gas industry

This project was a step forward in developing a 'descriptive theory' of contracting in the oil and gas industry that reflects the operating environment in which the project manager operates. This study investigates the existing processes and methods used in establishing contracts which are very often prescriptive, and not always appropriate or optimal for a given situation. This study contributes to contracting effectiveness or optimal contracting in the oil and gas industry.

Control design for positioning of underwater vehicles with control allocation

In this paper, we address the control design problem of positioning of over-actuated underwater vehicles. The proposed design is based on a control architecture with combined position and velocity loops and a control tuning method based on the decoupled models. We derive analytical tuning rules based on requirements of closed-loop stability, positioning performance, and the vehicle velocity dynamic characteristics. The vehicle modelling is considered from force to motion with appropriate simplifications related to low-speed manoeuvring hydrodynamics and vehicle symmetry. The control design is considered together with a control allocation mapping. This approach makes the control tuning independent of the characteristics of the force actuators and provides the basis for control reconfiguration in the presence of actuator failure. We propose an anti-wind-up implementation of the controller, which ensures that the constraints related to actuation capacity are not violated. This approach simplifies the control allocation problem since the actuator constraints are mapped into generalised force constraints.

Anti-wind-up designs for dynamic positioning of marine vehicles with control allocation

This paper presents a framework for the design of a joint motion controller and a control allocation strategy for dynamic positioning of marine vehicles. The key aspects of the proposed designs are a systematic approach to deal with actuator saturation and to inform the motion controller about saturation. The proposed system uses a mapping that translates the actuator constraint sets into constraint sets at the motion controller level. Hence, while the motion controller addresses the constraints, the control allocation algorithm can solve an unconstrained optimisation problem. The constrained control design is approached using a multivariable anti-wind-up strategy for strictly proper controllers. This is applicable to the implementation of PI and PID type of motion controllers.

Transformation in educational practices through STEM

The need for strong science, technology and innovation linkages between Higher Education Institutions (HEIs) and industries is a pivotal point for middle-income countries in their endeavor to enhance human capital in socioeconomic development. Currently, the University-Industry partnerships are at an infant stage in Sri Lankan higher education context. Technological maturity and effective communication skills are contributing factors for an efficient graduate profile. Also, expanding internship programs in particular for STEM disciplines provide work experience to students that would strengthen the relevance of higher education programs. This study reports historical overviews and current trends in STEM education in Sri Lanka. Emphasis will be drawn to recent technological and higher education curricular reforms. Data from the last 10 years were extracted from the higher education sector and Ministry of Higher Education Policy portfolios. Associations and trend analysis of the sector growth were compared with STEM existence, merger and predicted augmentations. Results were depicted and summarised based on STEM streams and disciplines. It was observed that the trend of STEM augmentation in the Sri Lankan Higher Education context is growing at a slow but steady pace. Further analysis with other sectors in particular, Industry information, would be useful and a worthwhile exercise.

Curse or cure? Revisiting state, capital and resources

WA’s experience, as portrayed in this volume, not only highlights the changeable nature of the mining industry, the volatility of global commodity markets and the impact of global capital on people and place, it also draws into question the promise of lasting value derived from resource development as currently practiced. It is in this context that Chapter 18 revisits WA's resource boom and assesses the sustainability of resource-led development in the state, to arrive at an answer to the question of ‘curse or cure?’. Opening up the discourse beyond the dominant developmentalist narrative invites discussion on new perspectives of economic sustainability that include well-being, equity and the protection of people, culture and place.

An efficient eAuction potocol

A secure protocol for electronic, sealed-bid, single item auctions is presented. The protocol caters to both first and second price (Vickrey) auctions and provides full price flexibility. Both computational and communication cost are linear with the number of bidders and utilize only standard cryptographic primitives. The protocol strictly divides knowledge of the bidder's identity and their actual bids between, respectively, a registration authority and an auctioneer, who are assumed not to collude but may be separately corrupt. This assures strong bidder-anonymity, though only weak bid privacy. The protocol is structured in two phases, each involving only off-line communication. Registration, requiring the use of the public key infrastructure, is simultaneous with hash-sealed bid-commitment and generates a receipt to the bidder containing a pseudonym. This phase is followed by encrypted bid-submission. Both phases involve the registration authority acting as a communication conduit but the actual message size is quite small. It is argued that this structure guarantees non-repudiation by both the winner and the auctioneer. Second price correctness is enforced either by observing the absence of registration of the claimed second-price bid or, where registered but lower than the actual second price, is subject to cooperation by the second price bidder - presumably motivated through self-interest. The use of the registration authority in other contexts is also considered with a view to developing an architecture for efficient secure multiparty transactions

Efficient one-time proxy signatures

One-time proxy signatures are one-time signatures for which a primary signer can delegate his or her signing capability to a proxy signer. In this work we propose two one-time proxy signature schemes with different security properties. Unlike other existing one-time proxy signatures that are constructed from public key cryptography, our proposed schemes are based one-way functions without trapdoors and so they inherit the communication and computation efficiency from the traditional one-time signatures. Although from a verifier point of view, signatures generated by the proxy are indistinguishable from those created by the primary signer, a trusted authority can be equipped with an algorithm that allows the authority to settle disputes between the signers. In our constructions, we use a combination of one-time signatures, oblivious transfer protocols and certain combinatorial objects. We characterise these new combinatorial objects and present constructions for them.

Efficient extension of standard Schnorr/RSA signatures into Universal Designated-Verifier Signatures

Universal Designated-Verifier Signature (UDVS) schemes are digital signature schemes with additional functionality which allows any holder of a signature to designate the signature to any desired designated-verifier such that the designated-verifier can verify that the message was signed by the signer, but is unable to convince anyone else of this fact. Since UDVS schemes reduce to standard signatures when no verifier designation is performed, it is natural to ask how to extend the classical Schnorr or RSA signature schemes into UDVS schemes, so that the existing key generation and signing implementation infrastructure for these schemes can be used without modification. We show how this can be efficiently achieved, and provide proofs of security for our schemes in the random oracle model.

An hybrid approach for efficient multicast stream authentication over unsecured channels

We study the multicast stream authentication problem when an opponent can drop, reorder and inject data packets into the communication channel. In this context, bandwidth limitation and fast authentication are the core concerns. Therefore any authentication scheme is to reduce as much as possible the packet overhead and the time spent at the receiver to check the authenticity of collected elements. Recently, Tartary and Wang developed a provably secure protocol with small packet overhead and a reduced number of signature verifications to be performed at the receiver. In this paper, we propose an hybrid scheme based on Tartary and Wang’s approach and Merkle hash trees. Our construction will exhibit a smaller overhead and a much faster processing at the receiver making it even more suitable for multicast than the earlier approach. As Tartary and Wang’s protocol, our construction is provably secure and allows the total recovery of the data stream despite erasures and injections occurred during transmission.

Fast, energy-efficient synthesis of luminescent carbon quantum dots

A simple, fast, energy and labour efficient, carbon dot synthesis method involving only the mixing of a saccharide and base is presented. Uniform, green luminescent carbon dots with an average size of 3.5 nm were obtained, without the need for additional energy input or external heating. Detection of formation moment for fructose-NaOH-produced carbon dots is also presented.

Highly efficient silicon nanoarray solar cells by a single-step plasma-based process

Highly efficient solar cells (conversion efficiency 11.9%, fill factor 70%) based on the vertically aligned single-crystalline nanostructures are fabricated without any pre-fabricated p-n junctions in a very simple, single-step process of Si nanoarray formation by etching p-type Si(100) wafers in low-temperature environment-friendly plasmas of argon and hydrogen mixtures.

Energy and matter-efficient size-selective growth of thin quantum wires in a plasma

It is shown that plasmas can minimize the adverse Gibbs-Thompson effect in thin quantum wire growth. The model of Si nanowirenucleation includes the unprecedented combination of the plasma sheath, ion- and radical-induced species creation and heating effects on the surface and within an Au catalyst nanoparticle. Compared to neutral gas thermal processes, much thinner, size-selective wires can nucleate at the same temperature and pressure while much lower energy and matter budget is needed to grow same-size wires. This explains the experimental observations and may lead to energy- and matter-efficient synthesis of a broader range of one-dimensional quantum structures.

Nanoscale control of energy and matter in plasma–surface interactions : toward energy- and matter-efficient nanotech

The approach to control the elementary processes of plasma–surface interactions to direct the fluxes of energy and matter at nano- and subnanometer scales is introduced. This ability is related to the solution of the grand challenge of directing energy and matter at nanoscales and is critical for the renewable energy and energy-efficient technologies for a sustainable future development. The examples of deterministic synthesis of self-organized arrays of metastable nanostructures in the size range beyond the reach of the present-day nanofabrication are considered to illustrate this possibility. By using precisely controlled and kinetically fast nanoscale transfer of energy and matter under nonequilibrium conditions and harnessing numerous plasma-specific controls of species creation, delivery to the surface,nucleation, and large-scale self-organization of nuclei and nanostructures, the arrays of metastable nanostructures can be created, arranged, stabilized, and further processed to meet the specific requirements of the envisaged applications.