Now showing items 1-20 of 8455

    • Ashes to Ashes: Identifying archaeological fuels

      Batt, Catherine M.; Bond, Julie M.; Griffin, Greggory A.
      Understanding fuel use is important in researching ancient communities. This project developed methods to identify archaeological fuel from midden, hearth, and ash samples using comparison to modern analogues. Modern analogue fuels were ashed at 2000C, 4000C, and 9000C then analysed with a suite of methods, the results were then used to inform the development of an approach for the identification of archaeological fuels. These methods were tested using samples from Ness of Brodgar, Knowe of Swandro, and Smerquoy/Muckquoy in Orkney. Magnetic susceptibility, scanning electron microscopy with energy dispersive X-ray spectroscopy, pH and Munsell colour assignment were chosen based upon previous archaeological, biofuel, and soil pollution research. The methodologies were refined with the analysis of ash from fuels including peat, seaweed, driftwood, willow, hazel, heather, grasses, cow dung, sheep dung, and bone. Modern analogue fuels at increasing temperatures showed an intensification in magnetism and alkalinity, and an alteration to mineral components during the chemical reaction of combustion that is indicative of fuel type and temperature. Principal components analysis confirmed matches between archaeological samples and modern ash, indicating a strong relationship between peat fuels and the archaeological samples. A correlation is also demonstrated between some of the archaeological samples and sheep dung, driftwood, willow, and animal bone. It is evident that each archaeological site has unique patterns of both fuel type and temperature. This shows that in the absence of abundant traditional wood fuel resources, the occupants of these sites used a combination of alternative fuels.
    • Capacity building of human resources in the oil and gas sector in Ghana: An exploration into the public-sector capacity building of human resources in the emerging oil and gas in Ghana

      Analoui, Farhad; Lawler, John A.; Amenshiah, Ambrose K.
      This empirical research explored the capacity building of human resources in the emerging oil and gas sector in Ghana. Ghana’s oil and gas were discovered in commercial quantities in 2007 by GNPC and its partners in Jubilee field in the Cape Three Point in the western region, which signified a turning point in the development effort of the state. Local skills shortage perceived as a significant challenge. Thus the government envisaged the need to build local skill capacity which attracted an initial grant of US$38 million from World Bank to facilitate the implementation of oil and gas capacity building project in 2010. The study adopted a mixed method approach for primary data collection. Matched samples of employees (226) working in four public sector organisations in the oil and gas sector were surveyed using the simple random technique, while human resource/training and development directors (9) were purposively sampled and interviewed on the human resources capacity building to assess and corroborates the survey data. The study findings confirmed shortcomings in local skills in the public organisations in the petroleum industry. Comparatively, the results suggested that the performance appraisal tools could be further improved. The study also found local skills mismatch. It revealed that inadequate funding and delays in the release of funds affected local skill capacity building in the public-sector organisations in the industry. Originality, this is one of the very few studies to explore the shortcomings of local skill capacity in the selected organisation including the strategies used in addressing the skill gap. Research implications, more matched-sample studies are necessary to understand further how private companies (IOC’s) contributing to local skill capacity building. Practically, the study is of significance to the policymakers to address the skill gap in the energy sector. The main contribution of the research is to conceptualise the concept of HRM in Ghana’s context. The thesis, therefore, is an essential contribution to our understanding of the skill gap in the oil and gas industry in Ghana and the role of HR in this field.
    • The Development of a Hybrid Knowledge-Based System for Lean Six Sigma Implementation in Healthcare Environment: The Development of a Hybrid Knowledge-Based (KB)/Gauging Absence of Pre-Requisites (GAP)/Analytical Hierarchy Process (AHP) Model for Implementing Lean Six Sigma System in Healthcare Environment

      Khan, M. Khurshid; Munive-Hernandez, J. Eduardo; Al Khamisi, Yousuf N.K.
      To improve their services and maintain patients’ satisfaction, healthcare organisations have adopted and applied different quality tools and models in recent times, with some even developing their own quality-based initiatives. For example, the approach of Lean Six Sigma (L6σ) has recently been gradually and slowly implemented in healthcare institutions. However, the nature and complexity of healthcare environment which directly impact on humans require leaders to carefully apply appropriate Quality Management (QM) systems suitable for this critical environment. The aim of this research project is to develop a Knowledge Based System (KBS) to assist healthcare managers and practitioners during decision-making process in the context of achieving excellent benchmark and action plans prioritisation. The system will be built based on a conceptual framework for Quality Management in Healthcare Environment (QMHE) which will be modified into a model. The KBS will be developed from this model with the integration of Gauging Absence of Pre-requisite (GAP) method for benchmarking and Analytical Hierarchy Process (AHP) method for prioritisation. The contribution of this research is the use of KBS with GAP and AHP to develop an integrated Knowledge-Based Lean Six Sigma (KB-L6σ) in QMHE. This will accomplish the necessities of investigating quality problems and recommend suitable solutions according to international best practices. It will use a systematic approach that can be applied multiple times, follow defined steps to secure consistency in the approach and integrate different healthcare management levels to maintain strategic decision-making alignment. It consists of 964 KB rules that have been produced via a knowledge acquisition process from the literature and interviewing experts in the field of QM and L6σ in healthcare environment. Feedback from conferences and system testing were used for the verification of the model, whilst validation was carried out through three case studies implementation at three tertiary hospitals in Oman. The analysis of using the KB system in these hospitals has shown clearly that the developed system is a consistent and reliable methodology for assisting decision-makers in designing, planning, and implementing L6σ for QMHE.
    • Virtual sensor for air mass flow measurement in an SI engine: Application of distributed lumped modelling in prediction of air mass flow into the cylinder of SI combustion engines

      Qi, Hong-Seng; Ebrahimi, Kambiz M.; Filippou, Sotirios
      After undergoing an extensive study about engine air mass flow measurement approaches as well as engine modelling for air mass flow prediction, a major problem found to exist is that engineers have still not found a suitable technique to accurately measure the air mass flow entering the cylinder of an internal combustion engine. The engine air mass flow is the most important parameter needed during engine development so the fuel control can be accurately calibrated and as a result increase performance and reduce emission output of an engine. The current methods used to determine the air mass flow lead to inaccuracies due to the large amount of mathematical assumptions and also sensor errors and as a result the mapping and calibration process of a new engine family takes approximately 2 years due to extensive modelling and testing required overcoming the above drawbacks. To improve this, the distributed lumped modelling technique (D-L) of the inlet manifold was chosen, where the intake system is separated into very small sections which are distributed continuously throughout the volume of the intake until entering the cylinder. This technique is validated against a CFD model of the engine’s intake system and real engine data as well as a 1D engine model.
    • Towards an Improved Framework of E-Government Implementation in Chaotic Environment; Proposed Social Collaboration Model: Case study of Libya

      Kamala, Mumtaz A.; Tassabehji, Rana; Khamallag, Masoud M.
      E-government is basically described as using all available electronic media to provide an online public services companies, agencies, citizens or persons in certain country or region. This provision can be provided by the government institutions, agencies, or organisation, in addition to public and private sectors subject to government policies and legislation. Political instability, armed conflict, corruption and chaotic situations are considered to be an obstacle confronting public services delivery and governance in some developing countries around the world. Therefore, Libya is selected a case study of this research. Post the 2011 ousting of the Gadhafi regime in Libya, the country has been experiencing a severe and deep-rooted environment of conflict and chaos, which has destabilised and in some cases dismantled government institutions throughout the country. Within this environment, the original aim of this study was to explore the possibility of implementing e-government services that can provide public services to citizens and, if so, how and what services could be utilised. An exploratory qualitative pilot study was conducted to investigate the feasibility of e-government implementation in Libya utilising the knowledge of government officials. The study found that, the Libyan government had recently and successfully implemented an online e-passport service. An extensive literature review carried out in relation to e-government implementation to help understanding lesions learned and factors behind such success then to utilise the knowledge for further services implementations. Critical success factors of e-government implementation were addressed but available ones are related to stable countries under normal situations. This research is aiming to investigate its implementation in chaotic environment where not much of research is available. During the chaotic environment and instability, different factors may emerge to drive the implementation and the usage of e-services such environment. From government perspectives, it is noticed that cases of corruption, lack of citizens’ safety and poor infrastructure were found to be drivers behind the success of existing government institutions and departments of implement e-passport system. Social collaboration and trust in government institutions’ commitment were emerged from the citizens’ perspectives as factors encouraged the citizens to use the e-passport system. Quantitative data analysed using structural equation modelling techniques using SmartPLS (3.2.7) together with the SPSS 23 were used to analyse the collected data. The outcome were used to propose a framework that can improve the implementation of public e-services while the country at unrest. Another contribution of this studies is the proposal of social collaboration model towards better e-services in such environment.
    • Assessing the risk of chemotherapy toxicity and hospital admission due to toxicity: A study of acute chemotherapy toxicity and related hospital admission in a large UK teaching hospital, based on proactive telephone assessment patients

      Silcock, Jonathan; Scally, Andy J.; Malton, Samuel R.
      Introduction: Acute chemotherapy toxicity is common and can have negative effects for the patient and health economy and hospitalisation can be necessitated. Aims: To identify the incidence of toxicity and admission, and predictors of toxicity occurrence, severity, hospitalisation and length of stay. Method: Data was obtained from a proactive telephone assessment of acute toxicity 24 hours after administration of a first cycle of chemotherapy to patients in a large UK NHS teaching hospital. Results: 1539 patients were studied and the overall incidence of toxicity was 35.6% (530 patients). Disease site and number of chemotherapy agents given were shown to predict toxicity, with breast and upper gastrointestinal cancers having a higher likelihood of toxicity. Disease was predictive of toxicity grade, with urology, gynaecology and lung cancer patients experiencing higher grades of toxicity than other tumour sites. The rate of hospital admission due to toxicity was 13.1% (203 patients) and median length of stay 3 days (1-28). The risk of admission had some risk factors in common with toxicity. Disease and the number of drugs in the regimen affected the risk of admission, with gynaecology, head and neck and lung cancer patients and patients who received 3 drugs having a higher likelihood of admission. Predictors in the subgroups of breast, colorectal and lung cancer patients did not differ greatly from the whole population and the number of drugs was shown to be a predictor of nausea, vomiting and fatigue when explored as secondary outcomes. Conclusion: The research partly addressed the main aim and highlighted areas where further research is required. Keywords
    • Design and Implementation of Radio Frequency Power Feeding Networks for Antenna Array Applications: Simulation and Measurements of Multiport, Equal and Unequal, Fixed and Reconfigurable Radio Frequency Power Feeding Networks for Narrow and Ultra-Wideband Applications

      Abd-Alhameed, Raed A.; Ali, Ammar H.A.
      Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications.
    • The Development of a Hybrid Knowledge-Based System for Integrated Maintenance Strategy and Operations in an Automotive Industry Environment: The Development of a Hybrid Knowledge-Based (KB) System/ Gauging Absences of Pre-Requisites (GAP)/Analytic Hierarchy Process (AHP) Methodology for Integrated Maintenance Strategy and Operations in an Automotive Industry Environment

      Munive-Hernandez, J. Eduardo; Khan, M. Khurshid; Milana, Milana
      The dependency of maintenance as a manufacturing logistic function has made the considerations of maintenance decisions complex in nature. The importance of maintenance has escalated significantly by the increasing of automation in manufacturing processes. This condition switches the traditional maintenance perspective of “fire-fighter” into the business competitive driver. As a consequence, maintenance needs to consider other related aspects of decision making to achieve competitive advantage. This research aims to develop a hybrid Knowledge-Based (KB) System/GAP/AHP methodology to support the integration of maintenance decision with business and manufacturing perspectives. It constructs over 2000 KB rules on Strategic Stage (business and manufacturing aspects) and Maintenance Operations Stage (maintenance aspects). Each aspect contains KB rules attached with GAP analysis to assess the gap between current and prerequisite condition. AHP analysis is then deployed to compare those aspects structurally in a pair-wise manner to identify the critical ones to be rectified. This hybrid KB system is useful in reviewing the existing maintenance system performance and provides reasonable recommendations to improve maintenance performance with respect to business and manufacturing perspectives. Eventually, it indicates the roadmap from the current state to the benchmark goals for the maintenance system. This novel methodology of KBS/GAP/AHP to support maintenance decision is developed for a particular application in the automotive environment. The validation is conducted in two automotive companies in Indonesia and one published case study in an automotive company. The result confirms that the developed KB system can provide the valid, reasonable and consistent result to propose structured recommendation for maintenance improvement priority.
    • Investigating the Transfer of Service Culture through Internal Service Quality: A Case of Subsidiary Hotels in an Emerging Market like Nigeria

      Liao, Mei-Na; Richardson, Sue; Maidugu, Joseph M.
      This study explores how foreign owned service firms with headquarters in developed markets transfer their service culture into a country with an emerging market like Nigeria. This study is motivated by the need to understand this process considering the unique features of these markets, and the expansion into countries with emerging markets by service firms located in countries with developed markets to take advantage of both natural and human resources. The research uses case studies of two hotels from different firms, both in Abuja, Nigeria, to explore activities that enhance the transfer of service culture from the Headquarters of these hotels based in the USA. Both hotels were investigated through semi-structured interviews, based on elements of internal service quality from the service profit chain model, in addition to documents and observation notes. The finding reveals the process of transferring service culture is difficult and complex because of unique contextual challenges. Some of these challenges were shown to be country specific, while some may be unique to countries with emerging markets. The country specific challenges include; strong religious allegiance and cultural affinity, and unique societal factors. Other factors could apply to any country with an emerging market these include; corruption, inadequate infrastructure, and lack of skilled labour. Similarly this study identified new elements that enabled both firms to address these challenges as well as enhance the transfer of focal areas in their signature service culture. Some of these elements have also been identified to be country specific i.e. inclusiveness and provision of social support, while the remaining three are emerging market specific i.e. transfer of knowledge and skills, accommodating corruption, and improvisation. These new elements also add to the existing five elements of internal service quality, which are employee selection, job description, reward and recognition, tools to serve customers, and workplace design. The study demonstrates the important role that intermediaries can play in achieving accommodations to achieve at least partial transfer of the parent service culture. Overall, the research contributes to management practice by highlighting areas to focus on when attempting to transfer service culture in similar circumstances. This thesis adds to the academic literature on the transfer of service culture from headquarters in a developed country to a unit in a country with an emerging market. It does this by extending concepts from the service profit chain to show how internal elements can enhance or block the transfer of service culture.
    • Federalism & post-conflict statebuilding: The case of Somalia

      aa, aa; Chevreau, Oliver M.
      The use of federalism as an integral component in post-conflict statebuilding processes is becoming increasingly common (e.g. Iraq, Yemen & Sri Lanka). The current academic literature, however, is divided between those that argue that federalism in such fragile environments will increase the likelihood of secession and ‘balkanisation’ and that those that argue that only federalism can provide the periphery with constitutionally protected rights against the centre. However, currently there is little empirical evidence to support either view. This research seeks to contribute to this gap by assessing whether the recent introduction of federalism in Somalia since 2013 has led to the delivery of tangible governance and peacebuilding outcomes. This thesis specifically focuses on the federalism process in Jubaland, a state which formed in 2013. Data was gathered across the region using a statistically significant perception survey and was supplemented by Key Informant Interviews. The surveys were designed to assess public opinion towards federalism and understand how its introduction was perceived to have impacted local governance and conflict dynamics. This analysis was further extended to assess the impact of federalism in other federal member states including Puntland, Galmadug and Southwest based on a review of available secondary literature. An analytical framework assessed the strength of Federal Government-Federal Member State, intra-state and inter-state relations and the extent to which a particular state had undertook tangible governance reforms. The key findings of the research indicate that the population in Jubaland is strongly supportive of federalism in principle and the manner in which it has been implemented. Federalism was seen by the majority of the population as a way of maintaining Somali unity whilst protecting local interests and meeting ocal needs. The approach of the Jubaland authorities to adopt a consociational approach to governance led to the establishment of a sustainable political settlement and the inclusion of minority groups for the first time. However, these successes have not been experienced more widely across Somalia. Other federal member states have experienced poor relations with the federal government. Internally, some states also have weak and violent relations with groups who are competing for influence and poor external relationships with other federal member states. In general, there is a low commitment to governance reform at federal-state level. These findings underpin the final conclusion that whilst federalism in Somalia has enabled improved governance and peacebuilding outcomes in Jubaland, it is the manner of how federal governance has been implemented in other federal states that explains the disparity in results across the country as a whole. More widely, this research suggests that federalism in post-conflict contexts is neither a panacea for peace and stability, or in of itself, a catalyst for inevitable fragmentation.
    • Genotoxic effects of NSAIDs and hydrocortisone in bulk and nano forms in lymphocytes from patients with haematological cancers

      Anderson, Diana; Normington, Charmaine
      Chronic inflammation is intimately linked with cancer development and progression and therefore reducing or eliminating inflammation represents a logical treatment and prevention strategy. Studies have shown that anti-inflammatory agents have anti-tumour effects in cancers, with reduced metastases and mortality. Current use of anti-inflammatory agents in the treatment and prevention of cancer is limited by their toxicity and side effects. The emerging field of nanotechnology allows the fundamental properties of a drug to be altered, creating a product with improved reactivity and bioavailability, leading to more targeted treatments and reduced dosage. In the present study, the genotoxic effects of three commonly used anti-inflammatory drugs; aspirin, ibuprofen and hydrocortisone, in their bulk and nano forms were evaluated on peripheral blood lymphocytes of healthy donors using the comet assay and the micronucleus assay. In order to determine any anti-cancer effects, these agents were also tested in peripheral blood lymphocytes in patients with haematological cancers. The glucocorticoid hydrocortisone was also evaluated for anti-oxidant capacity. Our results demonstrate that the nano versions of each drug produced a different response than the bulk counterpart, indicating that a reduction in particle size had an impact on the reactivity of the drug. Our results also indicate that the nano versions of each drug were less genotoxic than the bulk formulation, further emphasising the potential of nanoparticles as an improvement to current treatment options. We also found an anti-oxidant effect with hydrocortisone, with a more profound effect seen with the nano formulation.
    • Scheduling and Resource Efficiency Balancing: Discrete Species Conserving Cuckoo Search for Scheduling in an Uncertain Execution Environment

      Hu, Yim Fun; Li, Jian-Ping; Bibiks, Kirils
      The main goal of a scheduling process is to decide when and how to execute each of the project’s activities. Despite large variety of researched scheduling problems, the majority of them can be described as generalisations of the resource-constrained project scheduling problem (RCPSP). Because of wide applicability and challenging difficulty, RCPSP has attracted vast amount of attention in the research community and great variety of heuristics have been adapted for solving it. Even though these heuristics are structurally different and operate according to diverse principles, they are designed to obtain only one solution at a time. In the recent researches on RCPSPs, it was proven that these kind of problems have complex multimodal fitness landscapes, which are characterised by a wide solution search spaces and presence of multiple local and global optima. The main goal of this thesis is twofold. Firstly, it presents a variation of the RCPSP that considers optimisation of projects in an uncertain environment where resources are modelled to adapt to their environment and, as the result of this, improve their efficiency. Secondly, modification of a novel evolutionary computation method Cuckoo Search (CS) is proposed, which has been adapted for solving combinatorial optimisation problems and modified to obtain multiple solutions. To test the proposed methodology, two sets of experiments are carried out. First, the developed algorithm is applied to a real-life software development project. Second, performance of the algorithm is tested on universal benchmark instances for scheduling problems which were modified to take into account specifics of the proposed optimisation model. The results of both experiments demonstrate that the proposed methodology achieves competitive level of performance and is capable of finding multiple global solutions, as well as prove its applicability in real-life projects.
    • Towards Dementia Friendly Emergency Departments: A mixed method exploratory study identifying opportunities to improve the quality and safety of care for people with dementia in emergency departments

      Armitage, Gerry R.; Capstick, Andrea; Shaw, Courtney J.
      This project provides the first comprehensive investigation into the experiences of people with dementia (PWD), their carers, and the staff who provide care in emergency departments (ED) in the UK. This is a mixed methods study which used a national survey (N=403) followed by ED observation (32 hours) and qualitative interviews with health professionals (N=29), in an iterative and sequential design to present a holistic evaluation of the current experiences of the key parties- patients, carers, and ED staff involved in receiving and providing care. The theoretical perspective of the Human Factors Approach to patient safety underpins this work. The project included people with dementia and carers as collaborators and co-designers in both the development of the research tools and in shaping the project outputs. This research explores the barriers and facilitators to safe and effective care, concluding that here are a number of barriers (poor integration of communication systems, inappropriate physical environments, misalignment of staff training and workplace staffing models), which may affect the healthcare team’s ability to provide effective dementia care. These systemic challenges both give rise to and exacerbate poor organisational and safety cultures. However, despite these challenges, there are examples of safe and effective care (positive deviants) where uncommonly good outcomes for this patient population are achieved. Examining these examples offers valuable insight into potential adaptions, which could be used to improve existing care.
    • Evaluating Social Housing Sustainability Policies in the Context of Local Government: A Public Value Perspective

      Irani, Zahir; Kamal, M.M.; Sadiqi, Jawed
      The demand for social housing has grown recently more than its supply, particularly in the United Kingdom (UK). The existing literature addresses the lack of a sustainability policy and its contribution to the lack of political intent to support the achievement of social housing homeownership predominantly under the Right-to-Buy. This research highlights that several government projects have failed in the past to deliver satisfying outcomes for the public; thus, their value to social housing tenants and public value has been largely neglected. The main aim of this research project is to evaluate social housing policies through the lens of public value that drives the decision-making process and to construct a conceptual framework to enhance the accountability and efficiency of social housing tenants in the context of local government. This has been achieved through key research objectives and the key citizens, barriers and recommendations have been explored to enlighten social housing sustainability policy. This conceptual framework was tested in UK local government authorities and with local citizens who had recently started to address diverse sustainability factors in terms of social housing policy. The result was a qualitative case study enquiry based on the use of focus group-interviews, the vignettes approach and documentary evidence to explore the validity of the conceptual framework as a tool for supporting the decision-making process in this field. The findings obtained from the in-depth case study provided an insight into the social housing evaluation criteria and the influences of a sustainability policy from both a practical background and an internal organisational perspective. The findings addressed the poor affordability of a whole-life value of a property, insufficient funding due to austerity, poor legal frameworks, poor governance, a lack of suitable designs for social cohesion, poverty, the well-organized use of resources and environmental protection.
    • The IT way of loafing in class: Extending the theory of planned behavior (TPB) to understand students’ cyberslacking intentions

      Rana, Nripendra P.; Slade, E.; Kitching, S.; Dwivedi, Y.K. (2019-12)
      Internet-enabled technologies can facilitate students' learning, engagement, and productivity but they also present challenges by way of distraction. Cyberslacking is the use of internet-enabled technologies by students in class for non-class related activities. This research attempts to understand the factors that influence students' cyberslacking intentions in class, through extending the Theory of Planned Behavior with lack of attention, apathy towards course material, distraction by others, perceived threat, and escapism. Quantitative data were collected (n = 188) using a survey method with undergraduate and postgraduate students from a management school in a British university. All eight proposed hypotheses were found to be supported. The findings indicated that constructs such as lack of attention, apathy towards course material, and distraction by others are significant predictors of attitude. Further, attitude, subjective norm, perceived behavioral control, perceived threat, and escapism were found to significantly influence students’ cyberslacking intentions.
    • Correlating nano-scale surface replication accuracy and cavity temperature in micro-injection moulding using in-line process control and high-speed thermal imaging

      Baruffi, F.; Gülçür, Mert; Calaon, M.; Romano, J.-M.; Penchev, P.; Dimov, S.; Whiteside, Benjamin R.; Tosello, G. (2019-11)
      Micro-injection moulding (μIM) stands out as preferable technology to enable the mass production of polymeric components with micro- and nano-structured surfaces. One of the major challenges of these processes is related to the quality assurance of the manufactured surfaces: the time needed to perform accurate 3D surface acquisitions is typically much longer than a single moulding cycle, thus making impossible to integrate in-line measurements in the process chain. In this work, the authors proposed a novel solution to this problem by defining a process monitoring strategy aiming at linking sensitive in-line monitored process variables with the replication quality. A nano-structured surface for antibacterial applications was manufactured on a metal insert by laser structuring and replicated using two different polymers, polyoxymethylene (POM) and polycarbonate (PC). The replication accuracy was determined using a laser scanning confocal microscope and its dependence on the variation of the main μIM parameters was studied using a Design of Experiments (DoE) experimental approach. During each process cycle, the temperature distribution of the polymer inside the cavity was measured using a high-speed infrared camera by means of a sapphire window mounted in the movable plate of the mould. The temperature measurements showed a high level of correlation with the replication performance of the μIM process, thus providing a fast and effective way to control the quality of the moulded surfaces in-line.
    • Dynamic reliability assessment of flare systems by combining fault tree analysis and Bayesian networks

      Kabir, Sohag; Taleb-Berrouane, M.; Papadopoulos, Y. (2019)
      Flaring is a combustion process commonly used in the oil and gas industry to dispose flammable waste gases. Flare flameout occurs when these gases escape unburnt from the flare tip causing the discharge of flammable and/or toxic vapor clouds. The toxic gases released during this process have the potential to initiate safety hazards and cause serious harm to the ecosystem and human health. Flare flameout could be caused by environmental conditions, equipment failure, and human error. However, to better understand the causes of flare flameout, a rigorous analysis of the behavior of flare systems under failure conditions is required. In this article, we used fault tree analysis (FTA) and the dynamic Bayesian network (DBN) to assess the reliability of flare systems. In this study, we analyzed 40 different combinations of basic events that can cause flare flameout to determine the event with the highest impact on system failure. In the quantitative analysis, we use both constant and time-dependent failure rates of system components. The results show that combining these two approaches allows for robust probabilistic reasoning on flare system reliability, which can help improving the safety and asset integrity of process facilities. The proposed DBN model constitutes a significant step to improve the safety and reliability of flare systems in the oil and gas industry.
    • A Conceptual Framework to Incorporate Complex Basic Events in HiP-HOPS

      Kabir, Sohag; Aslansefat, K.; Sorokos, I.; Papadopoulos, Y.; Gheraibia, Y. (2019-10-11)
      Reliability evaluation for ensuring the uninterrupted system operation is an integral part of dependable system development. Model-based safety analysis (MBSA) techniques such as Hierarchically Performed Hazard Origin and Propagation Studies (HiP-HOPS) have made the reliability analysis process less expensive in terms of effort and time required. HiP-HOPS uses an analytical modelling approach for Fault tree analysis to automate the reliability analysis process, where each system component is associated with its failure rate or failure probability. However, such non-state-space analysis models are not capable of modelling more complex failure behaviour of component like failure/repair dependencies, e.g., spares, shared repair, imperfect coverage, etc. State-space based paradigms like Markov chain can model complex failure behaviour, but their use can lead to state-space explosion, thus undermining the overall analysis capacity. Therefore, to maintain the benefits of MBSA while not compromising on modelling capability, in this paper, we propose a conceptual framework to incorporate complex basic events in HiP-HOPS. The idea is demonstrated via an illustrative example.
    • Safety + AI: A novel approach to update safety models using artificial intelligence

      Gheraibia, Y.; Kabir, Sohag; Aslansefat, K.; Sorokos, I.; Papadopoulos, Y. (2019-09-16)
      Safety-critical systems are becoming larger and more complex to obtain a higher level of functionality. Hence, modeling and evaluation of these systems can be a difficult and error-prone task. Among existing safety models, Fault Tree Analysis (FTA) is one of the well-known methods in terms of easily understandable graphical structure. This study proposes a novel approach by using Machine Learning (ML) and real-time operational data to learn about the normal behavior of the system. Afterwards, if any abnormal situation arises with reference to the normal behavior model, the approach tries to find the explanation of the abnormality on the fault tree and then share the knowledge with the operator. If the fault tree fails to explain the situation, a number of different recommendations, including the potential repair of the fault tree, are provided based on the nature of the situation. A decision tree is utilized for this purpose. The effectiveness of the proposed approach is shown through a hypothetical example of an Aircraft Fuel Distribution System (AFDS).
    • Insights of Taste Masking from Molecular Interactions and Microstructures of Microspheres

      Zhang, Jiwen; Patterson, Laurence H.; Shao, Qun; Guo, Zhen
      The effects of taste masking are determined by interactions between drug and excipients as well as the microstructures of the particulate drug delivery systems (DDS). Cyclodextrin (CD) is a widely used taste masking agent, to which the relationship between kinetic parameters (Ka and Kd) of a drug and taste masking remains unexplored, which is investigated for the first time in this study. A data base of the kinetic parameters for drug-CD was established by Surface Plasmon Resonance Imaging (SPRi) and High Performance Affinity Chromatography (HPAC). Combined with the electronic tongue, Ka and Kd based models for the taste masking effect of HP-β-CD were successfully established and applied to the prediction of taste masking effects. Paracetamol was used as a model drug for taste masking formulation optimization. As well as drug release the microstructure of solid DDS has considerable influence on drug taste. The microstructure of lipid microspheres and the molecular distribution of drug and excipients in lipid microspheres were investigated by Synchrotron radiation-based micro-computed tomography (SR-μCT) and Synchrotron radiation-based Fourier-transform infrared spectromicroscopy (SR-FTIR), respectively. The results demonstrated that the polymeric formulation components as well as shape and particle size of the drug were the key factors to taste masking of paracetamol by inhibiting bust release thereby reducing the interaction intensity of the bitterness. The FTIR absorption spectra confirmed the deposition and formation of chitosan and gelatin films on the drug microsphere surface by layer-by-layer coating. In conclusion, this research demonstrates the molecular kinetic basis of CD taste-masking as well as microstructural basis of particle systems for bitter taste masking.