Evaluation of Various Dynamic Issues During Transient Operation of Turbocharged Diesel Engine with Special Reference to Friction Development

Copyright © 2007 SAE International The modeling of transient turbocharged diesel engine operation appeared in the early seventies and continues to be in the focal point of research, due to the importance of transient response in the everyday operating conditions of engines. The majority of research has focused so far on issues concerning thermodynamic modeling, as these directly affect heat release predictions and consequently performance and pollutants emissions. On the other hand, issues concerning the dynamics of transient operation are often disregarded or over-simplified, possibly for the sake of speeding up program execution time. In the present work, an experimentally validated transient diesel engin

WTA/TLA: A UAV-captured dataset for semantic segmentation of energy infrastructure

Automated inspection of energy infrastructure with Unmanned Aerial Vehicles (UAVs) is becoming increasingly important, exhibiting significant advantages over manual inspection, including improved scalability, cost/time effectiveness, and risks reduction. Although recent technological advancements enabled the collection of an abundance of vision data from UAVs’ sensors, significant efforts are still required from experts to interpret manually the collected data and assess the condition of energy infrastructure. Thus, semantic understanding of vision data collected from UAVs during inspection is a critical prerequisite for performing autonomous robotic tasks. However, the lack of labeled data introduces challenges and limitations in evaluating the performance of semantic prediction algorithms. To this end, we release two novel semantic datasets (WTA and TLA) of aerial images captured from power transmission networks and wind turbine farms, collected during real inspection scenarios with UAVs. We also propose modifications to existing state-of-the-art semantic segmentation CNNs to achieve improved trade-off between accuracy and computational complexity. Qualitative and quantitative experiments demonstrate both the challenging properties of the provided dataset and the effectiveness of the proposed networks in this domain.The dataset is available at: https://github.com/gzamps/wta_tla_dataset

Unpacking the complexity of the UK plastic packaging value chain: A stakeholder perspective

The pace to achieving a sustainable plastics economy remains noticeably slow. This could be due to a lack of understanding of the role and importance of stakeholder dynamics in the plastic packaging system. Therefore, this study aims to unpack and assess the role of stakeholders in improving the plastics recycling rate and circularity in the UK, using polyethylene terephthalate (PET) drinks bottles value chain as a case study. Via the theoretical lens of stakeholder theory the study identifies and groups the stakeholders in the PET drinks bottles value chain, and tries to make sense of, and analyse, their complex interactions via the use of the Complex Value Optimisation for Resource Recovery (CVORR) systems thinking approach. This integrated approach reveals, that even though external stakeholders (e.g. NGOs, trade associations) engage with internal stakeholders (e.g. suppliers, consumers, investors), and vice versa, at different levels and scales in promoting the circularity in the PET drink bottles value chain, there is a strong drive in incentivising the production and consumption processes. This is driven by the significant lobbying power of internal stakeholders operating upstream of the PET bottles value chain (i.e. producers and brand owners), that is supported by financial institutions, and which, strongly influences national and local government policies and decision-making processes. Meanwhile, the waste management processes are short-sighted, being unable to gain improved momentum and increase the PET bottles recycling rates. This dynamic conceals, and somewhat retains, the prevailing resistance in removing the infrastructural, regulatory and technological lock-ins. A collaboration between internal and external stakeholders is paramount to sustainably managing PET drinks bottles in the UK and achieving a transition to a sustainable circular plastics economy. Creating a level playing field and fostering a closer collaboration between all stakeholders involved in the system can aid the development of new value networks, and support new policy interventions that can improve circularity in the plastic packaging sector

Unpacking the complexity of the UK plastic packaging value chain: A stakeholder perspective

Copyright © 2021 The Author(s). The pace to achieving a sustainable plastics economy remains noticeably slow due to a lack of understanding on the role and importance of stakeholder dynamics in the plastic packaging system. This study aims to unpack and assess the role of stakeholders in improving plastics recycling rates and circularity in the UK, using polyethylene terephthalate (PET) drinks bottles value chain as a case study. Via the theoretical lens of stakeholder theory we identify and group the stakeholders involved in the PET drinks bottles value chain, and integrate this in the Complex Value Optimisation for Resource Recovery (CVORR) systems thinking approach to make sense of, and analyse, stakeholders complex interactions. Results highlight that even though, external stakeholders (e.g. NGOs, trade associations) engage on different levels and scales in promoting circularity in the PET bottles value chain, there is strong drive in incentivising production and consumption processes driven by the significant lobbying power of internal stakeholders operating upstream of the PET bottles value chain (i.e. producers and brand owners). This lobbying power, which arises from the well-established market of PET bottles in the UK, and its support by financial institutions, it strongly influences national and local government policies and decision-making processes. Meanwhile, the waste management processes are short-sighted, being unable to gain improved momentum and increasing the PET bottles recycling rates. This dynamic conceals, and somewhat retains, the prevailing resistance in removing the infrastructural, regulatory and technological lock-ins. The development of an interdisciplinary collaboration between internal and external stakeholders is paramount to sustainably managing PET drinks bottles in the UK and achieving a transition to a sustainable circular plastics economy. Fostering closer collaboration between all stakeholders involved in the system, can aid the development of new value networks and support new policy interventions that can improve circularity in the plastic packaging sector.Brunel University London as part of the Brunel Research Initiative & Enterprise Fund (BRIEF) award No.11683100, in the context of ‘Closing the Plastic Food Packaging Loop’ project, and generously supported by the Oxford Martin School, University of Oxford

Primary care professionals’ experiences during the first wave of the COVID-19 pandemic in Greece: a qualitative study

Background: The coronavirus outbreak (COVID-19) tested health care systems worldwide. This qualitative study aimed to explore and understand the experiences, beliefs and concerns of Primary Care Professionals (PCPs) regarding the preparedness and response of primary care to the first wave of the pandemic in Greece, a country where a public structured primary care system has been developing. Methods: We conducted semi-structured telephone interviews with 33 PCPs (General Practitioners, community General Internal Medicine Specialists, community Paediatricians and nurses) recruited from all regions of Greece after the first wave of the pandemic (June 2020). Interviews were transcribed verbatim, data were anonymised and analysed. Thematic analysis was applied developing a conceptual framework. Results: Four main themes were identified: a) Primary care unit adaptation and issues faced during the pandemic; b) Management of suspected COVID-19 cases; c) Management of non-suspected cases; d) Consequences of the pandemic. In the first phase of the pandemic, remote management of suspected cases and their referral to the hospital were preferred as a result of a shortage of personal protective equipment and inaccessibility to coronavirus testing in primary care. Due to the discontinuation of regular medical services and the limited in-person contact between doctors and patients, chronic disease management and prevention programmes were left behind. Social and emotional consequences of the pandemic, such as workplace stigma, isolation and social seclusion, deriving from fear of viral transmission, as well as burnout symptoms and exhaustion were commonly experienced among PCPs. Positive consequences of the pandemic were considered to be the recognition of the importance of an empowered public healthcare system by citizens and the valuable insight, knowledge and experience professionals gained in times of crisis. Conclusions: Primary care has a key role to play during and after the pandemic by using its information infrastructure to identify at-risk groups, detect new cases of COVID-19, provide care according to needs, and carry out vaccination programmes. Central coordination and empowerment of primary care will increase its effectiveness, via public awareness, holistic patient management, and unburdening of hospitals

Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Copyright © 2007 SAE International During the last decades, a vivid interest in the low heat rejection (LHR) diesel engine has arisen. In a LHR engine, an increased level of temperatures inside the cylinder is achieved resulting from the insulation applied to the combustion chamber walls. The steady-state LHR engine operation has been studied so far by applying either first- or second-law balances. However, very few works have treated this subject during the very important transient operation, with the results limited to the engine speed response. For this purpose, an experimentally validated simulation code of the thermodynamic cycle of the engine during transient conditions is applied. This takes into account the transient operation of the fue

Second-Law Analysis of Indirect Injection Turbocharged Diesel Engine Operation under Steady-State and Transient Conditions

Copyright © 2005 SAE International A second-law analysis is performed in both chambers of an indirect injection turbocharged diesel engine and the simulation program developed is used to study the second-law performance of the engine at various operating conditions, steady state and transient. The simulation developed is based on the filling and emptying approach and provides detailed analysis of thermodynamic, dynamic and second-law differential equations on a degree crank angle basis. It incorporates a detailed mathematical simulation of the fuel pump and solves each equation separately for each one of the six cylinders of the engine in hand. The model is validated against experimental data at steady state and transient conditions, obtained at the authors ’ laboratory. The prechamber rate and cumulative availability terms and irreversibilities are computed and depicted against the main chamber ones during the 720 degrees crank angle of an engine cycle. Moreover, the effect of certain parameters on the second-law performance of the cylinder is studied, i.e. static injection timing, prechamber diameter and engine load. Explicit diagrams are given to show the response of the various cylinders ’ main chamber and prechamber availability terms during transient operation. Thus, the magnitude as well as the evolution of the various terms during a cycle or during a transient event is highlighted