School of Engineering and Sustainable Development

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  • ItemEmbargo
    Enhancing Octree-based Context Models for Point Cloud Geometry Compression with Attention-based Child Node Number Prediction
    (IEEE, 2024-07-12) Sun, Chang; Yuan, Hui; Mao, Xiaolong; Lu, Xin; Hamzaoui, Raouf
    In point cloud geometry compression, most octree-based context models use the cross-entropy between the one-hot encoding of node occupancy and the probability distribution predicted by the context model as the loss. This approach converts the problem of predicting the number (a regression problem) and the position (a classification problem) of occupied child nodes into a 255-dimensional classification problem. As a result, it fails to accurately measure the difference between the one-hot encoding and the predicted probability distribution. We first analyze why the cross-entropy loss function fails to accurately measure the difference between the one-hot encoding and the predicted probability distribution. Then, we propose an attention-based child node number prediction (ACNP) module to enhance the context models. The proposed module can predict the number of occupied child nodes and map it into an 8-dimensional vector to assist the context model in predicting the probability distribution of the occupancy of the current node for efficient entropy coding. Experimental results demonstrate that the proposed module enhances the coding efficiency of octree-based context models.
  • ItemEmbargo
    Colored Point Cloud Quality Assessment Using Complementary Features in 3D and 2D Spaces
    (IEEE, 2024) Cui, Mao; Zhang, Yun; Fan, Chunling; Hamzaoui, Raouf; Li, Qinglan
    Point Cloud Quality Assessment (PCQA) plays an essential role in optimizing point cloud acquisition, encoding, transmission, and rendering for human-centric visual media applications. In this paper, we propose an objective PCQA model using Complementary Features from 3D and 2D spaces, called CF-PCQA, to measure the visual quality of colored point clouds. First, we develop four effective features in 3D space to represent the perceptual properties of colored point clouds, which include curvature, kurtosis, luminance distance and hue features of points in 3D space. Second, we project the 3D point cloud onto 2D planes using patch projection and extract a structural similarity feature of the projected 2D images in the spatial domain, as well as a sub-band similarity feature in the wavelet domain. Finally, we propose a feature selection and a learning model to fuse high dimensional features and predict the visual quality of the colored point clouds. Extensive experimental results show that the Pearson Linear Correlation Coefficients (PLCCs) of the proposed CF-PCQA were 0.9117, 0.9005, 0.9340 and 0.9826 on the SIAT-PCQD, SJTU-PCQA, WPC2.0 and ICIP2020 datasets, respectively. Moreover, statistical significance tests demonstrate that the CF-PCQA significantly outperforms the state-of-the-art PCQA benchmark schemes on the four datasets.
  • ItemOpen Access
    Utilizing Global-Local Neural Networks for the Analysis of Non-Linear Aerodynamics
    (Elsevier, 2024-07-02) Moni, Abhijith; Yao, Weigang; Malekmohamadi, Hossein
    In addressing the computational challenges pervasive in engineering where time and cost limitations are key concerns, particularly within the Computational Fluid Dynamics (CFD) domain, Reduced Order Models (ROMs) have emerged as instrumental tools. Focused on reducing computational complexity without intrusively modifying the computational model, this study centres on the strategic application of aerodynamic ROMs, which provide efficient computation of distributed quantities and aerodynamic forces. This work presents ROMs for non-linear aerodynamic applications, integrating principal component analysis (PCA) with Global Local Neural Networks (GLNN). The effectiveness of the proposed methodology is demonstrated by leveraging dependency on the parameter space created with non-linear high-fidelity CFD data, incorporating viscous simulation for a comprehensive approach. Results are first presented for a two-dimensional airfoil case and then for a three-dimensional test case featuring a transonic wing-body-tail transport aircraft configuration (NASA Common Research Model). In transonic flows, the proposed ROMs demonstrate the ability to accurately capture both the location and strength of shocks, as well as forces and moments for unseen prediction points. This highlights the efficiency of the proposed method in navigating complex aerodynamic scenarios, achieving comparable accuracy to full-order modelling but at orders of magnitude less computational time, for unseen parameters outside the ROM training set within the parameter space.
  • ItemOpen Access
    Farmers’ perceived effect of the COVID-19 pandemic and its relationship to preparedness and risk perception
    (Elsevier, 2024-06-14) Tyllianakis, Emmanouil; Otokiti, K. V.; Shahvi, S.; Martin-Ortega, J.
    The impact of the COVID-19 pandemic across the agri-food sector was significant and pervasive, challenging farmers' resilience through multiple disruptions to the supply chain. To support forward planning in face to future shocks, this research examines the perceived impacts of the COVID-19 pandemic by farmers themselves, providing insights from the UK. Using a nation-wide online survey carried out during two distinct waves of the pandemic in 2021, the study reveals changing perceptions and the relationship between preparedness and perceived impacts. Results indicate that perceptions of both the severity of the COVID-19 impacts and preparedness for such impacts in the future, were scaled down as the pandemic evolved. Findings suggest that a farmer feeling more prepared in the present to withstand shocks is positively influenced by them perceiving the impact of COVID-19's in their business as severe. This effect is reinforced for farmers that felt more prepared to withstand COVID-19's impacts when the pandemic unfolded, as well as for those that perceive the impact of COVID-19 as long-term. Farmers in our sample appear to have adapted to the shocks to their businesses through supply-side interventions, focusing on having higher flexibility in delivery of products and diversifying their supply networks. Doing so requires them to absorb an increase in both fixed and variable costs, which can end-up been transferred to the consumer. Government support moving forward should focus on strengthening and, perhaps, re-imagining the whole supply industry and re-defining the role of farmers as more than food producers, but also as stewards of climate and food resilience.
  • ItemOpen Access
    Feedback on Leicester City Council’s draft Climate Change Strategy and Action Plan
    (2020-05) Leicester Climate Emergency External Expert Commission; Reeves, Andrew
    This document summarises feedback put forward by members of the External Expert Commission (EEC) to Leicester City Council on their draft Climate Change Strategy and Action Plan documents.
  • ItemOpen Access
    Education for Sustainable Development and Academic Quality: Principles and Processes for Higher Education Providers
    (2023-06) Reeves, Andrew; Gwilliam, J.; Harrison, P.; Price, L.; Schantz, N.; Ribchester, C.; Hughes, T.; Gretton, S.; Strachan, S.; Logan, L.; Boxley, S.; Lengthorn, E.; Barrett, H.; Peres, S.
    This document reports the findings and recommendations from the “ESD and Academic Quality” QAA Collaborative Enhancement Project. Led by De Montfort University, the project aimed to identify how Academic Quality (AQ) processes could support adoption of Education for Sustainable Development (ESD) within Higher Education Institutions (HEIs). Our project has been driven by a focus on providing insights of value to HEI practitioners, recognising the diversity of roles of staff and students with an interest in ESD, and the great range of contexts within HEIs which will shape viable and appropriate approaches. Three aspects to this work that we agreed were highly significant are: 1) Institutional and departmental context is a key driver of what is possible in a particular HEI. This includes the nature and degree of strategic commitments to sustainable development and capacity of staff and students. 2) Whilst strategic commitments to sustainability or ESD are increasingly frequent, explicit inclusion of ESD in AQ and SV processes is still rare. It is therefore timely to produce a report highlighting specific examples of what this can look like from a range of settings. 3) Although addressing ESD in AQ and SV processes is an important component of its mainstreaming across an institution, it is likely to be ineffective without a wider enabling environment, that motivates and empowers students and staff to understand the agenda and put it into practice.
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    Household Energy Efficiency – why the older owner is stalled.
    (2023-12-04) Rowlatt, J.; Reeves, Andrew; Morton, A.; Brown, N.
    Data shows continued failure to meet new-build targets which combined with low current retrofit works means UK housing stock consistently falls behind energy efficiency targets. The properties of concern are owned outright and occupied by pensioners. This briefing provides an overview, including the drivers, impacts and current research data finishing with clear policy advice to address the systemic causes. All the necessary infrastructure required to apply policy, regulatory and education levers already exist.
  • ItemOpen Access
    Measuring and Reducing Carbon Emissions from Consumption of Goods and Services: The City of Leicester
    (2023-09) Aqqad, Yazeid; Reeves, Andrew
    Greenhouse gas (GHG) emissions that arise from the consumption of goods and services in cities can act as a significant contributor to climate change. A study conducted by the global C40 cities network found that in 80% of the cities examined, consumption-based emissions exceeded 50% of the city’s total emissions. Despite this, climate change governance and reporting typically follows a territorial-based approach, focussing upon emissions generated within a location. The UK follows this pattern, and for the City of Leicester, the quantified emissions in the city’s climate change strategy reflect scopes 1 and 2 (emissions directly produced in Leicester or arising from grid electricity used in the city). This report responds to a request from Leicester City Council to conduct desk-based research and modelling to help reduce ‘scope 3’ emissions from consumption of goods and services in Leicester by: 1. Calculating the consumption-based carbon emissions of the City of Leicester. 2. Proposing high-priority actions to reduce those emissions.
  • ItemOpen Access
    Measuring and Reducing Carbon Emissions from Consumption of Goods and Services: Local Authority Operations
    (2023-09) Aqqad, Yazeid; Reeves, Andrew
    Local authorities such as Leicester City Council (LCC) are responsible both directly and indirectly for generating carbon dioxide (and other greenhouse gas) emissions through their operations. A previous analysis of council emissions from 2011/12 estimated that consumption emissions for the council were 1.4 times larger than operational emissions at the time. Despite this, these emissions are not currently quantified or reported for either the city or the council in their annual carbon footprints, due in part to the cost and complexity of doing so. This report was requested by Leicester City Council to inform the development of future action by the council to reduce its own scope 3 emissions from consumption of goods and services by: 1. Identifying existing approaches to measuring or estimating council consumption emissions on an organisational and/or category basis – including using the information to set targets. 2. Identifying successful approaches and actions to reduce those emissions, including how the approaches/actions might be targeted to maximise the impact. A parallel report focusses on consumption-based emissions for the whole city of Leicester.
  • ItemOpen Access
    A Climate Emergency Action Plan Toolkit for Community Organisations: Pilot Study Results
    (2021-09) Kerr, Daniel; Reeves, Andrew; Hill, Bethan; Alhawamdeh, Aroob; Elmishri, Saja
    Leicester City Council (LCC) are encouraging businesses and organisations across Leicester to create their own Climate Emergency Action Plans, to play their part in the city’s efforts to achieve carbon neutrality by 2030. To support this, LCC are developing a standalone ‘Climate Emergency Action Plan toolkit’, which can be used by non-business community organisations in the city to develop their own action plans to reduce their carbon footprint (CF), and other negative environmental impacts through measures such as improved energy efficiency in buildings, modal shifts in transport or otherwise. This project aimed to aid development of this toolkit through piloting a small-scale offer of support and eliciting feedback on the draft resources.
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    Review of Leicester City Council’s Draft Climate Emergency Action Plan (2023-2028)
    (N/A, 2023-11-17) Leicester Climate Commission; Reeves, Andrew
    This short report by members of the Leicester Climate Commission has been produced as a response to viewing and discussing an October 2023 draft of Leicester City Council’s 2023-2028 Climate Emergency Action Plan. The report comprises a summary offering overall feedback, a small number of specific Recommendations for enhancements to the Action Plan and a list of Issues to Consider which were raised by Commission members as feedback.
  • ItemOpen Access
    Environmental sustainability of learning and teaching: Thematic Peer Group Report (Learning and Teaching Paper #14)
    (European University Association, 2021-03) Reeves, Andrew; European University Association
    This report provides an overview of the findings of the EUA Thematic Peer Group “Environmental sustainability of learning and teaching”. The group was tasked with discussing how learning and teaching can embrace and promote sustainability, and whether existing approaches to learning and teaching are sustainable. The report seeks to promote and guide action to enable the embedding of a holistic approach to sustainability in education and learning across higher education institutions. As the UN Sustainable Development Goals (SDGs) frame much of the existing activity and national and international debate in this area, the group chose them as the basis for its discussions. In addition, Education for Sustainable Development, a concept developed by UNESCO that acknowledges the central role of education in supporting sustainable development, guided the group’s work. In higher education, Education for Sustainable Development is not just an objective in itself, but also responds to many other objectives influencing the sector. Examples of such objectives include graduates developing creative approaches to address complex problems, institutions supporting social and economic development within their communities, and institutions instigating an adequate response to the global climate emergency. Sustainability agendas are reflected in multiple frameworks covering the higher education sector, such as the SDG Accord, the UN Academic Impact Initiative, and the Higher Education Sustainability Initiative and incorporation of sustainability issues into the activities of universities is sought by students (e.g. see National Union of Students Skills Survey) Further, the topic is also gaining traction at the European policy level, as evidenced by the European Commission‘s work on a Council Recommendation on Education for Environmental Sustainability. Because of the scope of action necessary to effectively incorporate the sustainability agenda into education and learning, the group argues that this cannot be confined solely to the “sustainability” remit of an institution. Rather, in order to achieve an effective and authentic delivery of sustainability in higher education, institutions need to engage their staff, students and partners in all areas of activity. This requires a transdisciplinary and cross-departmental approach, that aligns and embeds sustainability within all institutional strategic priorities, safeguarding against waning commitment, as for example has been witnessed in the context of the COVID-19 pandemic. The following realms in any institution must be strategically and practically engaged. • Sustainability as a value must be at the heart of all strategic activities and governance. • Sustainability must be acknowledged and effective as a framework for all educational activity, including all programmes, modules and extra-curricular activities. • Both the scope and delivery of research should be infused with the values of sustainability. • The management of the university and its facilities should reflect sustainability principles, such as the reduction of waste and efficient energy use. By doing so, the estate can serve as a “living lab”, enabling students and staff to experience and practically learn about sustainable lifestyles outside of the formal curriculum. • Institutional procurement strategies should incorporate a commitment to fair trade and to locally and environmentally sustainable principles. • Sustainability principles need to be embedded within civic engagement activities locally, nationally and globally. In order to achieve this ambition, the group argues that an institution must commit adequate resources, establish a common cause throughout its activities, develop the knowledge and skills of its staff, and be authentic in all its activities. Such a combination of high commitment and high capacity in implementing Education for Sustainable Development will lead to what the group terms “Integrated Impact”.
  • ItemEmbargo
    A comparative study of electrochemical stability and biocompatibility of TiN Nanowires and thin films for neural-electrode application
    (Elsevier, 2024-06-02) Sait, Roaa; Govindarajan, S.; Hussein, Deema; Alhowity, Alazouf; Baeesa, Saleh; Bangash, Mohammed; Abuzenadah, Adel; Cross, Richard
    Neural-electrode devices with adequate charge injection capacity, long operating lifetime and excellent biocompatibility with interfaced tissues are essential to treat chronic neurological disorders. The device’s efficiency hinges on the electrochemical properties of the electrode material, prompting extensive research on diverse material surfaces. Here, we investigate the electrochemical stability and biocompatibility of titanium nitride (TiN) nanowires (NWs) synthesized previously through the novel plasma enhanced chemical vapor deposition (PECVD) utilizing lower temperature as compared to conventional methods. These TiN-NWs were compared with TiN thin films, shedding light on their respective performances. TiN-NWs electrode revealed far superior electrochemical stability over 1000 cycles, achieving a capacitance retention of 93% as compared to 68% to that of TiN film electrode, under ambient conditions with dissolved oxygen. Moreover, our in-vitro cell culture spanning 20 days exhibited excellent biocompatibility for both substrates. Interestingly, cell distribution on the NWs appeared more dispersed with fewer clusters, potentially facilitating controlled electrical stimulation. These findings not only highlights the potential use of TiN-NWs for chronic stimulation of neurons, but also shows that surface morphology has a potential effect in minimising surface oxidation and improving electrochemial performance of the material.
  • ItemOpen Access
    Dependence-Based Coarse-to-Fine Approach for Reducing Distortion Accumulation in G-PCC Attribute Compression
    (IEEE, 2024-06-05) Guo, Tian; Yuan, Hui; Hamzaoui, Raouf; Wang, Xiaohui; Wang, Lu
    Geometry-based point cloud compression (G-PCC) is a state-of-the-art point cloud compression standard. While G-PCC achieves excellent performance, its reliance on the predicting transform leads to a significant dependence problem, which can easily result in distortion accumulation. This not only increases bitrate consumption but also degrades reconstruction quality. To address these challenges, we propose a dependence-based coarse-to-fine approach for distortion accumulation in G-PCC attribute compression. Our method consists of three modules: level-based adaptive quantization, point-based adaptive quantization, and Wiener filter-based refinement level quality enhancement. The level-based adaptive quantization module addresses the interlevel-of-detail (LOD) dependence problem, while the point-based adaptive quantization module tackles the interpoint dependence problem. On the other hand, the Wiener filter-based refinement level quality enhancement module enhances the reconstruction quality of each point based on the dependence order among LODs. Extensive experimental results demonstrate the effectiveness of the proposed method. Notably, when the proposed method was implemented in the latest G-PCC test model (TMC13v23.0), a Bjφntegaard delta rate of −4.9%, −12.7%, and −14.0% was achieved for the Luma, Chroma Cb, and Chroma Cr components, respectively.
  • ItemOpen Access
    Crowdsourced Estimation of Collective Just Noticeable Difference for Compressed Video with the Flicker Test and QUEST+
    (IEEE, 2024-05-17) Jenadeleh, Mohsen; Hamzaoui, Raouf; Reips, Ulf-Dietrich; Saupe, Dietmar
    The concept of videowise just noticeable difference (JND) was recently proposed for determining the lowest bitrate at which a source video can be compressed without perceptible quality loss with a given probability. This bitrate is usually obtained from estimates of the satisfied used ratio (SUR) at different encoding quality parameters. The SUR is the probability that the distortion corresponding to the quality parameter is not noticeable. Commonly, the SUR is computed experimentally by estimating the subjective JND threshold of each subject using a binary search, fitting a distribution model to the collected data, and creating the complementary cumulative distribution function of the distribution. The subjective tests consist of paired comparisons between the source video and compressed versions. However, as shown in this paper, this approach typically overestimates or underestimates the SUR. To address this shortcoming, we directly estimate the SUR function by considering the entire population as a collective observer. In our method, the subject for each paired comparison is randomly chosen, and a state-of-the-art Bayesian adaptive psychometric method (QUEST+) is used to select the compressed video in the paired comparison. Our simulations show that this collective method yields more accurate SUR results using fewer comparisons than traditional methods. We also perform a subjective experiment to assess the JND and SUR for compressed video. In the paired comparisons, we apply a flicker test that compares a video interleaving the source video and its compressed version with the source video. Analysis of the subjective data reveals that the flicker test provides, on average, greater sensitivity and precision in the assessment of the JND threshold than does the usual test, which compares compressed versions with the source video. Using crowdsourcing and the proposed approach, we build a JND dataset for 45 source video sequences that are encoded with both advanced video coding (AVC) and versatile video coding (VVC) at all available quantization parameters. Our dataset and the source code have been made publicly available at http://database.mmsp-kn.de/flickervidset-database.html.
  • ItemOpen Access
    Impact of Cu and Ce on the Electrochemical, Antibacterial, and Wear Properties of 316L Stainless Steel: Insights for Biomedical Applications
    (Elsevier, 2024-06-10) Yamanoglu, Ridvan; Trajkovska Petkoska, Anka; Ismail Yavuz, Hasan; Uzuner, Huseyin; Drienovsky, Marian; Nasov, Ilija; Khoshnaw, Fuad
    This study provides a comprehensive investigation of the tribological, electrochemical, and antibacterial characteristics of austenitic stainless steel, type 316L, doped with Ce and Cu. The samples were doped with varying concentrations of Ce (0.5, 1.5, and 3 wt%) and Cu (1.5, 2.5, and 3.5 wt%). The initial measurements focused on determining the final density values of each sample. Subsequently, friction wear tests were conducted under both dry and wet conditions, shedding light on the wear resistance of the materials. In addition, electrochemical polarization tests were employed to assess the influence of Ce and Cu on the corrosion resistance of AISI 316L. Furthermore, antibacterial assessments were conducted against bacterial cultures of Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). The findings of this study illuminate several noteworthy outcomes. Namely, the results showed that all Ce and Cu-doped samples exhibited an increase in final density values when compared with the asreceived AISI 316L. The wear test results revealed that samples doped with 0.5 wt% Ce and 2.5 wt% Cu exhibited the highest wear resistance, in both dry and wet environments. Polarization curve analysis indicated that Ce was more effective in enhancing the corrosion resistance of AISI 316L than Cu. Notably, Ce and Cu modifications endowed the material with antibacterial properties, effectively inhibiting bacterial growth in both S. aureus and E. coli cultures. In summary, this study demonstrates that the addition of even trace amounts of Ce and Cu to AISI 316L leads to noticeable improvements in the material's tribological, electrochemical, and antibacterial performance, underscoring its potential for diverse biomedical applications. The enhanced mechanical strength, corrosion resistance, and antibacterial activity make the doped material promising for use in various medical devices, implants, and other biomedical applications.
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    Influence of Surface Chemical and Topographical Properties on Morphology, Wettability and Surface Coverage of Inkjet-Printed Graphene-Based Materials
    (MDPI, 2024-05-22) Salaoru, Iulia; Morris, Dave; Ware, Ecaterina; Nama Manjunatha, Krishna
    The inkjet printing of water-based graphene and graphene oxide inks on five substrates, two rigid (silicon and glass) and three flexible (cellulose, indium tin oxide-coated polyethylene terephthalate (ITO-PET) and ceramic coated paper (PEL paper)), is reported in this work. The physical properties of the inks, the chemical/topographical properties of selected substrates, and the inkjet printing (IJP) of the graphene-based materials, including the optimisation of the printing parameters together with the morphological characterisation of the printed layers, are investigated and described in this article. Furthermore, the impact of both the chemical and topographical properties of the substrates and the physical properties of graphene-based inks on the morphology, wettability and surface coverage of the inkjet-printed graphene patterns is studied and discussed in detail.
  • ItemOpen Access
    Data-Driven Nonintrusive Model-Order Reduction for Aerodynamic Design Optimization
    (AIAA, 2024-05-13) Moni, Abhijith; Yao, Weigang; Malekmohamadi, Hossein
    Fast and accurate evaluation of aerodynamic characteristics is essential for aerodynamic design optimization because aircraft programs require many years of design and optimization. Therefore, it is imperative to develop sufficiently fast, robust, and accurate computational tools for industry routine analysis. This paper presents a nonintrusive machine-learning method for building reduced-order models (ROMs) using an autoencoder neural network architecture. An optimization framework was developed to identify the optimal solution by exploring the low-dimensional subspace generated by the trained autoencoder. To demonstrate the convergence, stability, and reliability of the ROM, a subsonic inverse design problem and a transonic drag minimization problem of the airfoil were studied and validated using two different parameterization strategies. The robustness and accuracy demonstrated by the method suggest that it is valuable in parametric studies, such as aerodynamic design and optimization, and requires only a small fraction of the cost of full-order modeling.
  • ItemOpen Access
    Laser Surface Engineering for Tribology
    (MDPI, 2024-05) Ji, Xiulin; Sun, Yong
    This book is a reprint of the Special Issue Laser Surface Engineering for Tribology that was published in Lubricants
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    Digitally enabled business models for a circular plastic economy in Africa
    (Elsevier, 2024-05-02) Kolade, Oluwaseun; Oyinlola, M. A.; Ogunde, Olawunmi; Ilo, Celine; Ajala, Olubunmi
    In recognition of the need for an economic logic that complements and reinforces the ecological imperative for the circular plastic economy, this paper explores the importance and impact of digitally enabled circular plastic business models across retailing and distribution systems. The paper draws from 16 focus group discussions, complemented by 17 semi-structured interviews of frontline organisations incorporating digital innovations in their businesses to enable the management of plastic waste in Africa. The study finds that, across African countries, the transition to a circular plastic economy has been hampered by the limited uptake of circular products by consumers. In order to accelerate the transition, innovative business models are required to invigorate the ecosystem and simplify the logistics of retailing and distribution systems. The paper proposes a new conceptual framework that explicates the impact of digital innovations in the processes of value creation and value capture across a whole spectrum of circular economy reverse logistics activities: recycling, redistribution, and remanufacture. The study also highlights two important social and policy implications of digitally-enabled circular business models: Firstly, the creation of new employment opportunities through the empowerment of a new labour force for the circular plastic economy; secondly, the heightened opportunity to enact an innovative sharing economy in typically resource-constrained contexts in which otherwise idle products and resources are more efficiently used in a process of collaborative consumption.