7,977 research outputs found

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    An empirical investigation of the relationship between integration, dynamic capabilities and performance in supply chains

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    This research aimed to develop an empirical understanding of the relationships between integration, dynamic capabilities and performance in the supply chain domain, based on which, two conceptual frameworks were constructed to advance the field. The core motivation for the research was that, at the stage of writing the thesis, the combined relationship between the three concepts had not yet been examined, although their interrelationships have been studied individually. To achieve this aim, deductive and inductive reasoning logics were utilised to guide the qualitative study, which was undertaken via multiple case studies to investigate lines of enquiry that would address the research questions formulated. This is consistent with the author’s philosophical adoption of the ontology of relativism and the epistemology of constructionism, which was considered appropriate to address the research questions. Empirical data and evidence were collected, and various triangulation techniques were employed to ensure their credibility. Some key features of grounded theory coding techniques were drawn upon for data coding and analysis, generating two levels of findings. These revealed that whilst integration and dynamic capabilities were crucial in improving performance, the performance also informed the former. This reflects a cyclical and iterative approach rather than one purely based on linearity. Adopting a holistic approach towards the relationship was key in producing complementary strategies that can deliver sustainable supply chain performance. The research makes theoretical, methodological and practical contributions to the field of supply chain management. The theoretical contribution includes the development of two emerging conceptual frameworks at the micro and macro levels. The former provides greater specificity, as it allows meta-analytic evaluation of the three concepts and their dimensions, providing a detailed insight into their correlations. The latter gives a holistic view of their relationships and how they are connected, reflecting a middle-range theory that bridges theory and practice. The methodological contribution lies in presenting models that address gaps associated with the inconsistent use of terminologies in philosophical assumptions, and lack of rigor in deploying case study research methods. In terms of its practical contribution, this research offers insights that practitioners could adopt to enhance their performance. They can do so without necessarily having to forgo certain desired outcomes using targeted integrative strategies and drawing on their dynamic capabilities

    Enhancing GNSS RTK Solutions with Random Sample Consensus

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    Precise positioning with Global Navigation Satellite Systems (GNSS) can be achieved by using the real-time kinematic (RTK) solution. A GNSS RTK solution was improved using an innovative approach based on Random Sample Consensus (RANSAC). RANSAC pre-filters carrier phase measurements based on the inherent consistency among GNSS satellites. This method improves the reliability and accuracy of an RTK system with low-cost receivers and antennas, especially in a GNSS-challenged environment. In this work, the integration of RANSAC and RTK is demonstrated with recorded live GNSS data

    TRANSEUNTIS MUNDI, A NOMADIC ARTISTIC PRACTICE

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    In this practice-led Ph.D. research, I investigate how an artistic practice can respond to the migration phenomena performed by human beings across the planet over millennia ¬– what I refer to as the millennial global human journey. Based on the idea of mobility, I chose to frame this research in the articulation of concepts deriving from the prefix trans: transculture, transhumance and transmediality. This research contributes to studies in art composition by developing the processes and concept of transmedial composition, mainly contributing to the field of New Media Art. This investigation resulted in the work Transeuntis Mundi (TM) Project – a nomadic artistic practice that encompasses: the TM Derive and manual, the TM Archive, the TM VR work Derive 01 and two forms for its notation. Transeuntis mundi (TM), from the Latin language, means the ‘passersby of the world’ and metaphorically personify in this work the millennial migrants and their global journeys. Based on proposals from the Realism art movement and the walking-based methodologies of Walkscapes and Dérive, the TM Derive was created as a nomadic methodology of composition in response to the ideas of migration and ancestry. It is framed by the minimal stories ¬– the form of narrative of this work, captured from field recordings with 3D technology of everyday life worldwide. This material formed the TM Archive, presented in the TM VR work. The TM VR work Transeuntis Mundi Derive 01 is an immersive and interactive performative experience for virtual reality, that artistically brings together stories, sounds, images, people, and places worldwide, ¬as a metaphor of the millennial global human migration. This work happens as a VR application using 3D technology with 360º image and ambisonic sound, in order to promote an engaged experience through the immersion and interactivity of the participant. This thesis presents and contextualizes these creations: the scope, references, concepts, origin, collaborations, methodology, technologies, and results of this work. It is informed and accompanied by reflexive and critical writing, including an articulation with references of works across different artistic media and fields.UNIRIO Federal University of the State of Rio de Janeir

    Improving approaches to material inventory management in construction industry in the UK

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    Materials used in construction constitute a major proportion of the total cost of construction projects. An important factor of great concern that adversely affects construction projects is the location and tracking of materials, which normally come in bulk with minimal identification. There is inadequate integration of modern wireless technologies (such as Radio Frequency Identification (RFID), Personal Digital Assistant (PDA) or Just-in-Time (JIT)) into project management systems for easier and faster materials management and tracking and to overcome human error. This research focuses on improving approaches to material inventory management in the UK construction industry through the formulation of RFID-based materials management tracking process system with projects. Existing literature review identified many challenges/problems in material inventory management on construction projects, such as supply delays, shortages, price fluctuations, wastage and damage, and insufficient storage space. Six construction projects were selected as exploratory case studies and cross-case analysis was used to investigate approaches to material inventory management practices: problems, implementation of ICT, and the potential for using emerging wireless technologies and systems (such as RFID and PDA) for materials tracking. Findings showed that there were similar problems of storage constraints and logistics with most of the construction projects. The synthesis of good practices required the implementation of RFID-facilitated construction management of materials tracking system to make material handling easier, quicker, more efficient and less paperwork. There was also a recommendation to implement Information and Communication Technology (ICT) tools to integrate plant, labour and materials into one system. The findings from the cases studies and the literature review were used to formulate a process for real-time material tracking using Radio Frequency Identification (RFID) that can improve material inventory management in the UK construction industry. Testing and validation undertaken assisted in formulating a process that can be useful, functional and acceptable for a possible process system’s development. Finally, research achievements/contributions to knowledge, and limitations were discussed and some suggestions for further research were outlined

    LASSO – an observatorium for the dynamic selection, analysis and comparison of software

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    Mining software repositories at the scale of 'big code' (i.e., big data) is a challenging activity. As well as finding a suitable software corpus and making it programmatically accessible through an index or database, researchers and practitioners have to establish an efficient analysis infrastructure and precisely define the metrics and data extraction approaches to be applied. Moreover, for analysis results to be generalisable, these tasks have to be applied at a large enough scale to have statistical significance, and if they are to be repeatable, the artefacts need to be carefully maintained and curated over time. Today, however, a lot of this work is still performed by human beings on a case-by-case basis, with the level of effort involved often having a significant negative impact on the generalisability and repeatability of studies, and thus on their overall scientific value. The general purpose, 'code mining' repositories and infrastructures that have emerged in recent years represent a significant step forward because they automate many software mining tasks at an ultra-large scale and allow researchers and practitioners to focus on defining the questions they would like to explore at an abstract level. However, they are currently limited to static analysis and data extraction techniques, and thus cannot support (i.e., help automate) any studies which involve the execution of software systems. This includes experimental validations of techniques and tools that hypothesise about the behaviour (i.e., semantics) of software, or data analysis and extraction techniques that aim to measure dynamic properties of software. In this thesis a platform called LASSO (Large-Scale Software Observatorium) is introduced that overcomes this limitation by automating the collection of dynamic (i.e., execution-based) information about software alongside static information. It features a single, ultra-large scale corpus of executable software systems created by amalgamating existing Open Source software repositories and a dedicated DSL for defining abstract selection and analysis pipelines. Its key innovations are integrated capabilities for searching for selecting software systems based on their exhibited behaviour and an 'arena' that allows their responses to software tests to be compared in a purely data-driven way. We call the platform a 'software observatorium' since it is a place where the behaviour of large numbers of software systems can be observed, analysed and compared

    Leveraging Ethereum platform for development of efficient tractability system in pharmaceutical supply chain

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    Consumer knowledge of the goods produced or processed by the numerous suppliers and processors is still relatively low due to the growing complexity of the structure of pharmaceutical supply chains. Information asymmetry in the pharmaceutical sector has an effect on welfare, sustainability, and health. (1) Background: In this respect, we wanted to develop a productive structure for a pharmaceutical supply chain that satisfies the consumer information needs and fosters consumer confidence in the pharmacy goods they buy. By using blockchain technology, the main goals were to develop and implement a pharmaceutical supply chain. (2) Objectives: The main objectives of this work were to leverage an Ethereum platform for the development of a tractability system in a pharmaceutical supply chain environment and to analyze the efficiency of MSMAChain with respect to the cost and execution of transactions based on our designed smart contracts. (3) Results: This research looked into a variety of issues related to the value, viability, and effects of blockchain technology for use in supply chain applications. The methods and creations in this environment were monitored and researched. It is vital to identify a number of crucial subjects including future research areas, in order to achieve the widespread acceptance of the supply chain traceability provided by blockchain technology. (4) Conclusions: MSMAChain, an Ethereum blockchain-based approach, leverages smart contracts and decentralized off-chain storage for efficient product traceability in terms of the cost and execution of transaction for a health care supply chain

    Voltage Profile Control of Active Distribution Networks

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    This thesis presents a method for voltage profile control in active distribution networks with solar photovoltaic integration. It proposes a hierarchical control technique which utilizes minimal information techniques to monitor and control the voltage profile and the reactive power flow of a given unbalanced distribution network. The hierarchical control consists of three levels responsible for maintaining the distribution network's voltage profile and losses, thereby increasing its efficiency. Firstly, the thesis explores the influence of rising photovoltaic penetration in distribution networks to understand the voltage rise pattern and its impacts on the network's power losses and loading conditions. The exploration was followed by an analysis of local voltage control techniques which exploit the photovoltaic inverter capabilities by providing detailed comparison based on simulation results. The main concept, advantages, limitations, and weather scenarios in which these techniques are most suitable are discussed, and possible coordination of these techniques to realise lesser voltage violations is proposed. Secondly, due to the local control's inability to maintain all node voltages within predefined limits, pilot points are selected in the distribution network to represent the voltages of other load buses coupled with it in a manner that voltage variation at these points would represent the voltage variation within the network. Then an optimal coordinated voltage control algorithm based on only pilot point information to minimise the voltage deviations at all load buses in the distribution networks is proposed. The pilot points are obtained using a proposed multi-objective formulation considering multiple operating conditions for solar photovoltaic generation, loads, and electric vehicle uncertainties. Thirdly, a reactive optimal power flow is proposed to obtain optimal reference voltages for pilot points used in distribution networks. The algorithm employs a non-linear interior point method and differential evolution to minimise the overall distribution network's system losses, thereby improving the network's efficiency. Finally, the proposed methods are tested and validated on IEEE test systems and an actual large distribution feeder in New South Wales, Australia. Furthermore, the methods proposed are also compared further with other approaches to justify their superiority

    Elements of Ion Linear Accelerators, Calm in The Resonances, Other_Tales

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    The main part of this book, Elements of Linear Accelerators, outlines in Part 1 a framework for non-relativistic linear accelerator focusing and accelerating channel design, simulation, optimization and analysis where space charge is an important factor. Part 1 is the most important part of the book; grasping the framework is essential to fully understand and appreciate the elements within it, and the myriad application details of the following Parts. The treatment concentrates on all linacs, large or small, intended for high-intensity, very low beam loss, factory-type application. The Radio-Frequency-Quadrupole (RFQ) is especially developed as a representative and the most complicated linac form (from dc to bunched and accelerated beam), extending to practical design of long, high energy linacs, including space charge resonances and beam halo formation, and some challenges for future work. Also a practical method is presented for designing Alternating-Phase- Focused (APF) linacs with long sequences and high energy gain. Full open-source software is available. The following part, Calm in the Resonances and Other Tales, contains eyewitness accounts of nearly 60 years of participation in accelerator technology. (September 2023) The LINACS codes are released at no cost and, as always,with fully open-source coding. (p.2 & Ch 19.10)Comment: 652 pages. Some hundreds of figures - all images, there is no data in the figures. (September 2023) The LINACS codes are released at no cost and, as always,with fully open-source coding. (p.2 & Ch 19.10
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