Contourite cyclicity and deposition

Cyclic depositional features are commonly developed in deepwater sedimentary facies. Stacked sequences in varied forms is the most obvious characteristic, which is related to complex variation in depositional conditions. This study introduces several geostatistical approaches to analyse the cyclical bi-gradational sequences of contourite deposits from IODP Expedition 339 in the Contourite Depositional System (CDS) in the Gulf of Cadiz. It analysed both the vertical sequences and their cyclicity and their lateral correlation, both qualitatively and quantitatively. Additionally, similar geostatistical approaches were applied to colour sequences in turbidite and hemipelagite deposits from the Benguela Current Upwelling System, SW African continental margin. This allowed comparison of sequences and cyclicity between the different deepwater facies types. It also demonstrated the general applicability of this method to deepwater sedimentary facies. This study systematically examined contourite bi-gradational sequences deposited at IODP Sites U1386 and U1387 between mid-Pleistocene to Recent. Transition probability analysis based on the lithological logs confirmed the statistical validity of typical bi-gradational sequences composed of coarsening-upward to fining-upward contourite divisions. These typically ranged in thickness from 0.5-5m. Variations caused by minor erosion and non-deposition resulted in incomplete sequences and complex sequences with multiple gradational divisions. The cyclic patterns of contourite bi-gradational sequences varied to some extent between each studied hole. The 3-layer-sequence (C1-C2-C4-C5) dominates in this study area, and a few sequences with more than 4 divisions include the C3 (sandy) division. Autocorrelation of sequence duration in all studied holes indicates the existence of long-term cyclicity of around 350 ky. The succession can be subdivided into 4 stages (0-350 ka, 350-700 ka, 750-1000 ka and >1000 ka) with alternating occurrence of more frequent and coarser sequences and less frequent finer-grained sequences. Cross-correlation of this long-term sequence frequency as well as of individual sequences shows moderately good but not perfect correlation between holes and sites. This study suggests contourite deposition at the study sites is controlled by both bottom current strength (speed) and sediment supply, both of which can most probably be related to a complex variation in paleoclimate evolution and orbital cycles In hemipelagite and turbidite-hemipelagite hybrid deposits beneath the Benguela Upwelling System off SW Africa, two colour sequence models (Hemipelagite Dominant Sequence and Turbidite Hemipelagite Hybrid Sequence) were developed based on light-dark variation related to organic matter content. Autocorrelation of sequence duration pointed out long-term cyclicity through the past 4 My (0-1 Ma, 1-2.5 Ma, 2.5- 4 Ma and >4 Ma), which can be correlated to stages in tthe long-term evolution of the Benguela Current Upwelling System. Lateral correlation between studied sites indicated differences of sequence frequency in time and space, which further contributed to reconstruction of the upwelling system. The geostatistical study of cyclicity in contourite bi-gradational sequences and its comparison cyclic characteristics of other deepwater facies (turbidites and hemipelagites), demonstrates that such geostatistical approaches can be an important technique to evaluate the basic sedimentary character of different systems and their numerical expression. It allows for comparison between facies types and for better correlation with other time series records, such as orbital climate patterns. Cyclic signatures can be correlated between different sites and help better understand the sedimentary processes involved in their deposition

Multi qubit gates using ZZ interactions in superconducting circuits

In recent years quantum computing has shown great promise and has come on in leaps and bounds. The promise of quantum computers is the speed-up over classical computers in specific areas and hence the ability to tackle even more complex problems. As quantum computers evolve the need for more complex quantum gates requiring more qubits (multi qubit gates) arises. These gates are currently broken down into their one and two qubit gates. Multi qubit gate decomposition’s involve many two qubit gates leading to the fidelity of these gates needing to be much higher in order to produce a usable multi qubit gate. A possible solution to this is to introduce a single shot method for the multi qubit gates. In this thesis we investigate the use of dispersive shifts to create these single shot methods. We examine two scenarios, first being a relatively simple three qubit gate (the iToffoli gate) to demonstrate the procedure. We then move to extend this method to a larger number of qubits examining its uses in quantum error correction and noting the potential pitfalls of this method. This thesis is organised as follows. In Chapter 1 we shall introduce the topic of superconducting circuits discussing some simple circuits such as the LC Oscillator and showing how these circuits can be modified to model superconducting qubits. We shall also introduce the topic of Quantum Computing giving an overview of the topic, discussing some quantum gates which shall be used and finally a short introduction to Quantum Error Correction. In Chapter 2 we shall show how we implemented a single shot multi qubit gate within superconducting circuits. We shall introduce some of the methods and analysis procedures we use within this thesis and show numerical evidence of this gate. In Chapter 3 we shall discuss an extension of the gate mechanism of chapter 1 to larger qubit clusters and show how it can be modified to implement parity check gates and show how they can be used to implement the stabilizer measurements used in the surface code. Finally in chapter 4 we shall discuss the future of this work, looking at some possible future directions for this research and suggesting some other more novel avenues which could be explored

Accountability relationships and populism in the Greek National Health System. Evidence from the 1980s

The aim of this thesis is to examine accountability in the Greek National Health system in regard to the emerging managerialism that prevailed in the Western countries since the 1980s. The distinction between political and managerial accountability has been utilised for the conceptualisation of empirical data. The theory of populism was used in order to interpret accountability relationships and explain the impact of the political environment on accountability. Parliamentary debate and the press of the period were examined, and they demonstrated that populism was a dominant force in the public debate. Populism was expressed as fierce polarisation on behalf of the government towards the opposition and it constituted a major way of political accountability. In this context, accounting was not a part of the legitimation scheme and there was direct clash between populism and the discourses of accounting. We also examined how this context was transfused into organisational practices. For this reason, we conducted interviews with people who were involved in the System. Analysis has shown that populism also had significant impact on organisations, as it was translated to severe partisanism and created clientelistic networks which monopolised power. Political accountability infiltrated in organisations through populism, dominated all aspects of accountability and it was turned to partisan accountability. As a result, managerial accountability was overshadowed, and it was never allowed to operate as a system for more efficient control. In fact, managerialism was victimised as a potential threat to the existing status. This thesis contributes to the examination of accountability beyond the Anglo-Saxon context, which dominates scientific literature. Additionally, it provides insights regarding the impact of politicians on accountability and accounting. Moreover, it proposes populism as a new theoretical framework for accountability, because it can have significant impact in a specific setting. Consequently, this thesis aims at further improving the understanding of accounting within the context in which it operates

CO2 injection for enhanced gas condensate recovery : an experimental and theoretical study

CO2 injection in gas condensate reservoirs has been identified as a viable technique for alleviating condensate banking and enhancing gas condensate recovery (EGCR) favoured due to prospects of storing CO2 in long terms. Multiple-contact miscibility (MCM) with vaporising method is recommended to extract maximum gas condensate and avoid leaving precious gas condensate fractions behind. The research involves extensive PVT and core flood tests using CO2 and a binary gas condensate fluid sample across a range of core permeabilities. Steady-state CO2- condensate relative permeability data is gathered to improve H-n-P CO2 injection simulations for enhanced gas condensate recovery and CO2 storage. The Schlumberger E300 compositional simulator was employed to simulate incremental H-n-P CO2 injection, shut-in, and production cycles, mirroring laboratory experiments. The simulation results emphasize the importance of using accurate CO2-GC kr data and accounting for compositional changes during H-n-P CO2 injection. In the following chapters, a practical framework was suggested based on the results to accurately identify and quantify the effects of CO2-GC interaction during CO2 injection for enhanced gas condensate recovery. Furthermore, the miscibility pressure of CO2 and gas condensate sample was optimised to enhance the swelling and vaporisation mechanism and determine the best injection scenarios at pressures below and above the dew point for optimal gas condensate recovery and CO2 storage purposes. The hydrocarbon recovery efficiency of the suggested injection technique for EGCR was tested on high to ultra-low permeability core samples. The recovery efficiency of this optimised plan was observed to surpass the conventional H-n-P CO2 injection albeit with five times less the volume of CO2 required during the conventional injection approach. The volume of injected CO2 was constrained by pressure limits over which the variation in maximum condensate saturation is minimal. Results indicate that condensate recovery significantly improves, reaching 69.7% after the fourth H-n-P CO2 injection cycle, with 49.5% additional condensate recovery post primary depletion phase and 48.6% cumulative CO2 storage. At the end of the proposed H-n-P CO2 injection, the total gas produced had an 85.9% and a 14.1% hydrocarbon and CO2 content respectively. The experimental data reported in this thesis allow bridging the gap between conflicting reports on the CO2-GC fluid interactions at pressures below and above the dew point pressure (PDew) and provides a solid cornerstone to design optimised H-n-P CO2 injection scenarios for EGCR and CO2 storage purposes

The synthesis and derivation of tetra-substituted methylene bridge calix[4]arenes

Chapter 1 discusses the history of calix[n]arenes dating back to the initial investigation of the phenol-formaldehyde procedure up to the seminal work by Gutsche that developed the synthesis of these macrocycles allowing ease of access. Modification of these macrocycles is discussed on the upper- and lower-rim followed by a detailed look into different methods utilised to build functionalisation at the methylene bridge. Finally, methods of introducing multiple functionalities to the methylene bridge is considered. Chapter 2 presents the synthesis of a previously reported calix[4]arene which has been mono-substituted at the methylene bridge containing a saturated 1,4 diketone. This compound is then used as an intermediate to the synthesis of pyrrole appended C[4]s through the Paal-Knorr synthesis with a range of different anilines. A library of these C[4]s is presented with observations and discussions. Chapter 3 contains a further look into the Paal-Knorr synthesis using the saturated 1,4 diketone intermediate with a set of long chain alkyl-amines. The exploration into other heterocycles is then discussed including a synthesis of a thiophene using the 1,4 saturated intermediate and a 1,4 unsaturated diketone with subsequent pyridazine ring closure. The deprotection of the pyridazine, Thiophene and a long chain alkyl pyrrole is discussed along with issues encountered, how they are overcome and decomposition of these compounds. Chapter 4 discusses introducing pyridyl functionality at the methylene bridge using the Paal-Knorr synthesis. The different methods considered and trialled followed by synthesis of two extended anilines and the reaction of 2-,3- and 4-(pyridyl)aniline with the 1,4 saturated diketone forming the respective pyrroles, the products synthesised and how these could be used to form asymmetrical calix[4]arenes. Chapter 5 is a summary and overview of the work presented in this thesis with a small section on the possible future work in this area

Risk management practices among SMEs in Nigeria : contribution to business success

Empirical research on how SMEs manage risk in practice is very scant. However, given the strategic contribution of SMEs to economic development and their susceptibility to risks, a more active risk management (RM) practice is increasingly seen as critical to their success and survival. Hence, this study explored how SMEs in Nigeria perceive and practice risk management and the extent to which SME owners and managers attribute their business success to RM practices. The research adopted an exploratory, qualitative multiple-case study method, using 11 Lagos SMEs as case studies. Data collection was through semi-structured interviews with 23 owners and managers across the SMEs. These SMEs were purposively selected from five sectors, namely: Education, Manufacturing, Wholesale/Retail Trade, Human Health and Social Work, Accommodation and Food Services sectors, and have been operating successfully between seven and 29 years. The interviews were augmented by document analysis. Data collected were analysed through thematic and cross-case synthesis to identify themes and patterns that emerged across all the SMEs. Findings suggest that the SMEs are aware of the risk facing their business and recognise the importance of actively engaging in RM. The research established that the SMEs carry out RM activities without necessarily acknowledging them as such or utilising complex RM tools and techniques. Strategies commonly used by the SMEs in mitigating risks were identified as Monitoring and Supervision, Awareness Creation, Planning, Stakeholder Management, Supplier Management, Partnership and Collaboration, Insurance, Networking, Enforcement and Agreement. Most of the SMEs attributed their existence, growth and expansion, waste/loss reduction and ease of access to bank loans to their RM activities. The research also identified the motivating factors for the SMEs to enhance their current RM procedures. The research contributed to existing theory and knowledge on RM in SMEs from Nigeria's perspective, with a focus on Lagos State. Another contribution is in the suggested approaches through which the SMEs can improve awareness, understanding and attitude to risk among all their managers and employees. Further, contributions were made in the recommendations to policymakers and financial institutions on how to support SME growth and development through RM considerations

Embrace concept drift : a novel solution for online continual learning

Continual learning is a critical area of research in machine learning that aims to enable models to learn new information without forgetting the old knowledge. Online continual learning, in particular, addresses the challenges of learning from a stream of data in real-world environments where data can be unbounded and heterogeneous. There are two main problems to be addressed in online continual learning: the first one is catastrophic forgetting, a phenomenon where the model forgets the previously learned knowledge while learning new tasks; the second one is concept drift, a situation where the distribution of the data changes over time. These issues can further complicate the learning process, compared to traditional machine learning. In this thesis, we propose a general framework for online continual learning that leverages both regularization-based and memory-based methods to mitigate catastrophic forgetting and handle concept drift. Specifically, we introduce a novel concept drift detection algorithm based on the confidence values of the samples. We present a novel online continual learning paradigm, which utilizes concept drift as a rehearsal signal to improve performance by consolidating or expanding the memory center. We also apply data condensation approaches to online continual learning in order to perform memory efficient rehearsal. Furthermore, we evaluate the accuracy of old tasks and new tasks, comparing with many benchmark models. We present a novel evaluation metric - Stability and Plasticity Balance to measure the balance between old and new accuracy. We evaluate our proposed approach on a new benchmark dataset framework, Continual Online Learning (COnL), which consists of two scenarios of online continual learning: class-incremental learning and instance-incremental learning. In this thesis, the benchmark dataset framework randomly selects a number of incremental classes from 3 different datasets: TinyImageNet, Germany Traffic Sign and Landmarks. Our primary results demonstrate that concept drift can be a useful tool in memory rehearsal in the online continual learning setting. Our proposed approaches provide a promising direction for future research in online continual learning and have the potential to enable models to learn continuously from unbounded and heterogeneous data streams in real-world environments

Bundling as a strategy for a commodity service brand introduction. The impact of bundle partner image on quality and risk perception and the role of complementarity

Increasing the quality perception and reducing the perceived risk of purchase improves the chances of success for new service introductions. This research investigated whether, for a new service brand introduction into the German residential electricity market, bundling with a stronger service brand enhances the perceived quality and reduces the perceived risk more than bundling with a weaker brand. In the goods category, it has been scientifically shown prior to this research that bundling with a stronger brand achieves this effect if the products are complementary. An academic knowledge gap in this area existed because this enhancement effect was yet to be evaluated empirically for services. This research applied price bundling to a new electricity service brand introduction via a survey experiment with potential customers rating electricity bundle offers. The research design was a 2*2 (brand image of bundle partner; complementarity) factorial design with analysis of variance (ANOVA) to test the research hypotheses. The results narrow the knowledge gap and contribute to professional practice by establishing that bundling with a stronger brand enhances the perceived quality and reduces the perceived risk also for services. The research furthermore demonstrated that complementarity is, independent of the bundle partner brand image, a factor to improve quality perception and to reduce the perceived risk of a new service brand

Optical ground receivers for satellite based quantum communications

Cryptography has always been a key technology in security, privacy and defence. From ancient Roman times, where messages were sent cyphered with simple encoding techniques, to modern times and the complex security protocols of the Internet. During the last decades, security of information has been assumed, since classical computers do not have the power to break the passwords used every day (if they are generated properly). However, in 1984, a new threat emerged when Peter Shor presented the Shor’s algorithm, an algorithm that could be used in quantum computers to break many of the secure communication protocols nowadays. Current quantum computers are still in their early stages, with not enough qubits to perform this algorithm in reasonable times. However, the threat is present, not future, since the messages that are being sent by important institutions can be stored, and decoded in the future once quantum computers are available. Quantum key distribution (QKD) is one of the solutions proposed for this threat, and the only one mathematically proven to be secure with no assumptions on the eavesdropper power. This optical technology has recently gained interest to be performed with satellite communications, the main reason being the relative ease to deploy a global network in this way. In satellite QKD, the parameter space and available technology to optimise are very big, so there is still a lot of work to be done to understand which is the optimal way to exploit this technology. This dissertation investigates one of these parameters, the encoding scheme. Most satellite QKD systems use polarisation schemes nowadays. This thesis presents for the first time an experimental work of a time-bin encoding scheme for free-space receivers within a full QKD system in the second chapter. The third and fourth chapter explore the advantages of having multi-protocol free-space receivers that can boost the interoperability between systems, polarisation filtering techniques to reduce background. Finally, the last chapter presents a new technology that can help increase communications rates

Developing an implementation framework for Lean Six Sigma in high-value and low-volume industries

High-value low-volume (HVLV) industries hold a strong relevance in Germany, with a focus on complex engineering and large projects conducted at low frequencies. Methodologies for continuous improvement (CI), such as Lean Six Sigma (LSS), have been used in mass production industries, such as automotive, to promote operational excellence and are now relevant in HVLV industries to survive amid growing international competition. The implementation of LSS in the HVLV industries has not yet been studied to much extent. Therefore the purpose of the present study is to develop an implementation framework for Lean Six Sigma in the wind power industry in Germany. To develop the conceptual framework, a systematic literature review of critical success factors (CSFs) and critical failure factors (CFFs) was conducted. The review identified similarities between the CSFs and CFFs which often reflected opposite conditions of the same variable. The present study connects the success and failure factors as critical influencing factors (CIFs), which include reasons for both failure and success. An analysis of five relevant implementation frameworks of LSS shows that none of the frameworks fully includes all CIFs and do not provide a complete answer concerning LSS implementation in terms of what should be done to secure success and avoid failure in the process. The chosen research paradigm was critical realism and the research method was action case in combination with action learning. The outcome of the study was an implementation framework for LSS, the 3D framework house, as the essential result of the research, which was validated by LSS experts. The present study contributes to scholarship with the 3D framework house and a cycle approach in 18 steps, as well as with the detailed description of the newly defined CIFs with the focus dimensions and with the HVLV-specific focus dimensions. It contributes to practice with the improved situation in the research organisation and with the clear guideline for practitioners, giving answers to the questions “what needs to be done” to improve the situation of the CIFs of LSS, “how this can be implemented” and “who is responsible” in the HVLV industry context