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Conceptual design study based on defined parameters for next-generation Martian rotorcrafts
Get PDFThe remarkable achievement of NASA’s Ingenuity Helicopter has opened exciting possibilities for the future exploration of Mars, suggesting that aerobots will play a crucial role alongside rovers and landers. However, Ingenuity’s capabilities are limited by its small and relatively basic design. This limitation is primarily evident in its restricted long-range endurance and limited capacity for scientific payloads. To address these shortcomings and advance the field of Martian drone technology, this paper introduces a practical approach to optimising the Martian rotorcraft concepts within the set parameters. The primary objective of these concepts is to enhance performance, endurance, and payload capacity to meet more demanding requirements for future Martian aerobot missions. The paper addresses an essential phase in the design process—an initial sizing of rotary electric vertical takeoff and landing (eVTOL) configurations. This phase is informed by a comprehensive parametric analysis, which considers various factors affecting the performance of drones during hover (stationary flight), vertical climb (ascending flight), and forward flight. The analysis is based on the principles of simplified rotorcraft momentum theory, a foundational concept in rotorcraft engineering. These Martian drone concepts are tailored to address the more challenging mission requirements that future Martian exploration missions are likely to demand. These requirements may include extended flight durations, increased payload capacity to accommodate scientific instruments, and the ability to cover larger areas on the Martian surface. Importantly, the designs are constrained by the maximum size of the spacecraft aeroshell, ensuring that they can be safely transported to Mars within the confines of the protective aeroshell. Among the various configurations considered in this study, a tandem rotorcraft configuration emerged as the most efficient option. This configuration is expected to attain a balance between performance, endurance, and payload capacity, making it a promising choice for future Martian aerobot missions. In contrast, the analysis revealed that a conventional single main rotor configuration within the defined parameters performed poorly in meeting the requirements of the mission.IEEE Aerospace Conferenc
Constructed wetlands as nature-based solutions in managing per-and poly-fluoroalkyl substances (PFAS): evidence, mechanisms, and modelling
Get PDFPer- and poly-fluoroalkyl substances (PFAS) have emerged as newly regulated micropollutants, characterised by extreme recalcitrance and environmental toxicity. Constructed wetlands (CWs), as a nature-based solution, have gained widespread application in sustainable water and wastewater treatment and offer multiple environmental and societal benefits. Despite CWs potential, knowledge gaps persist in their PFAS removal capacities, associated mechanisms, and modelling of PFAS fate. This study carried out a systematic literature review, supplemented by unpublished experimental data, demonstrating the promise of CWs for PFAS removal from the influents of varying sources and characteristics. Median removal performances of 64, 46, and 0 % were observed in five free water surface (FWS), four horizontal subsurface flow (HF), and 18 vertical flow (VF) wetlands, respectively. PFAS adsorption by the substrate or plant root/rhizosphere was deemed as a key removal mechanism. Nevertheless, the available dataset resulted unsuitable for a quantitative analysis. Data-driven models, including multiple regression models and machine learning-based Artificial Neural Networks (ANN), were employed to predict PFAS removal. These models showed better predictive performance compared to various mechanistic models, which include two adsorption isotherms. The results affirmed that artificial intelligence is an efficient tool for modelling the removal of emerging contaminants with limited knowledge of chemical properties. In summary, this study consolidated evidence supporting the use of CWs for mitigating new legacy PFAS contaminants. Further research, especially long-term monitoring of full-scale CWs treating real wastewater, is crucial to obtain additional data for model development and validation.This research is gratefully supported by the project sponsor Anglian Water. P. Savvidou's PhD study is supported by Atkins Realis and the EPSRC Centre for Doctoral Training in Water Infrastructure and Resilience (EP/V519509/1). We also acknowledge support from the BBSRC/EPSRC Environmental Biotechnology Network (EBNet) NIBB (BB/S009795/1).Science of The Total Environmen
A decision support system for selection and risk management of sustainability governance approaches in multi-tier supply chain
Get PDFLower-tier suppliers' sustainability noncompliance and focal company's failure at meeting the expectations of the stakeholders to extend sustainability towards lower-tier suppliers carry multiple risks, tangible and intangible, to the focal company. It is expected that extending sustainability to suppliers at lower tiers through effective sustainability governance approaches (SGAs) can reduce these risks for focal companies. The existing literature lacks research on decision support tools using management science techniques to help decision makers choose the most suitable SGA/SGAs in a given situation and the risk management of SGAs in multi-tier supply chain. The present study develops a model-driven decision support system (DSS) using Bayesian network (BN) that can assist operations managers in selecting the most effective SGA/SGAs in multi-tier supply chain considering each situation. The developed DSS includes contingency factors and risk variables and their relationships which are identified through a systematic literature review and is applied to the multi-tier, sustainable supply chain of a multinational company operating in China to demonstrate its practical applicability. The DSS is then used in the risk management of the SGAs in multi-tier supply chain, which includes core steps such as identification of the contingency factors and risk variables, the prioritisation of the contingency factors and risk treatment. By Prioritising the basic contingency factors, ‘‘Focal company's sustainability knowledge’’ and ‘‘The specific nature of the materials sourced from lower-tier supplier’‘, and ‘‘First-tier supplier's possession of internal resources'’ and ‘‘First-tier supplier's sustainability training’’ were identified as the two most important factors regarding their impact on the effectiveness of the direct and indirect approaches respectively. Detailed managerial implications related to the development and implementation of the DSS and the risk management process are also provided
Understanding microplastic presence in different wastewater treatment processes: removal efficiency and source identification
Get PDFMunicipal effluents discharged from wastewater treatment plants (WWTPs) are a considerable source of microplastics in the environment. The dynamic profiles of microplastics in treatment units in WWTPs with different treatment processes remain unclear. This study quantitatively analyzed microplastics in wastewater samples collected from different treatment units in two tertiary treatment plants with distinct processes. The influents contained an average of 15.5 ± 3.5 particles/L and 38.5 ± 2.5 particles/L in the two WWTPs with in the oxidation ditch process and the integrated fixed-film activated sludge process, respectively. Interestingly, microplastic concentrations in the influent were more influenced by the population density in the served area than sewage volume or served population equivalent. Throughout the treatment process, concentrations were reduced to 1.5 ± 0.5 particles/L and 1.0 ± 1.0 particles/L in the final effluents, representing an overall decrease of 90% and 97%, in WWTPs with the oxidation ditch process and integrated fixed-film activated sludge process, respectively. A significant proportion of the microplastics were removed during the primary treatment stage in both WWTPs, with better performance for foam, film, line-shaped and large-sized microplastics. Most microplastics were accumulated in activated sludge, indicating its key role as the primary sink in WWTPs. The multiple correspondence analysis identified laundry washing and daily necessities such as packaging and containers as the major contributors to microplastics in WWTPs. The study proposed recommendations for upgrading WWTPs, modifying designs, and implementing strategies to reduce microplastic sources, aiming to minimize the release of microplastics into the environment. These findings can shed lights on the sources of microplastics in WWTPs, and advance our understanding of the mechanisms for more effective microplastic removals in wastewater treatment technologies in future applications.Science of The Total Environmen
Development of Sustainable PPE for Higher Threat Clearance Operations by Humanitarian Organisations
Get PDFPoster contribution to the Defence and Security Doctoral Symposium 2023 DN
Protecting Publicly Accessible Locations from Terrorism: Towards a strategic framework for Kenya
Get PDFPaper presentation to the Defence and Security Doctoral Symposium 2023
Polarimetrically augmented Coherent Change Detection three stage detector for laboratory multistatic Synthetic Aperture Radar
Get PDFPaper presentation to the Defence and Security Doctoral Symposium 2023 DST
Development of Sustainable PPE for Higher Threat Clearance Operations by Humanitarian Organisations
Get PDF3MT contribution to the Defence and Security Doctoral Symposium 2023 DN
Toward a new model of democracy promotion for state and non-state actors: the conceptualization of the Donald Trump America first foreign policy and impact on democracy and democratization process
Get PDFThe Trump presidency has come to an end, but academic debate on his ‘America First’ foreign policy is still in full swing. Academics who engage the subject either disagree that Trump developed a distinct foreign policy or agree that he did. Those who agree that he did, still disagree on the type and impact. Thus, the three key academic questions that underpin the Trump ‘America First’ foreign policy are: 1) How do we conceptualize the Trump ‘America First’ foreign policy? 2) What impact does it have on democracy and democratization? 3) How do state and non-state actors of democracy promotion respond effectively to this impact? This research makes conceptual and theoretical contribution to U.S foreign policy schools of thought and International Relations. It identifies five patterns in the Trump policy that provides the theoretically backed basis for re-conceptualization; 1) Pattern against international system/multilateral institutions; 2) Unilateral pattern; 3) Pattern against pro-democracy leaders; 4) Pro-Putin pattern; and 5) nick-naming/populist pattern. The study argues that a U.S foreign policy that displaces U.S stewardship of the international system and replaces the two main pillars of liberalism; multilateralism and globalism, with unilateralism and Americanism creates the conditions for global waves of autocratization and anarchy
Qualitative responses to Hydrogen Homes (H2H) Online Survey 2022.docx
No full textThis file records responses given by online survey participants in the UK (N = 1845) to a questionnaire on the domestic hydrogen transition, which was programmed using Qualtrics. The data collection period lasted between 06/10/2023 and 23/12/2023, supported by a professional market research company (Savanta). The survey duration was approximately 15 to 20 minutes. Domestic hydrogen refers to hydrogen-fuelled appliances for heating and cooking, collectively referred to as hydrogen homes. All survey responses were measured using either a five-point or eleven-point Likert scale.At the end of the survey, participants were requested to respond to the following open-ended question which concluded the survey: Please use this text box to explain more about your attitudes towards hydrogen or any other reflections on this topic.Around two-thirds of respondents (N = 1213) provided a valid response. The sample was composed of four specific consumer sub-groups, which returned a relatively balanced response rate (M = 66.3%; SD = 3.0). In published materials, we use the term Hydrogen Homes (H2H) dataset to denote outputs from this project.'DTP 2020-2021 Cranfield University