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Conference paperMorrison L, McPherson A, 2024,
Entangling entanglement: a diffractive dialogue on HCI and musical interactions
, CHI Conference on Human Factors in Computing Systems, Publisher: ACMIf, as several recent papers claim, we have entered a new wave of “Entanglement HCI,” then we are still at a liminal stage prior to consensus around which sources underpin this paradigm shift or how they might inform actionable approaches to design practice. Now is the time to interpret technosocial mediation from a range of disciplinary perspectives, rather than settling on a narrow canon of literature. To this end, our paper enacts a diffractive dialogue between researchers from different disciplines, focusing on digital musical instruments to examine how technical knowledge from design and engineering can be read against the grain of critical theories from music, media, and cultural studies. Drawing on two object lessons—keyboards and step sequencers, plus their remediations inrecent musical interaction research—we highlight interdependencies of theory, design, and practice, and we show how the idea of entanglement is itself entangled in a cross-disciplinary web.
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Conference paperSadek M, Constantinides M, Quercia D, et al., 2024,
Guidelines for integrating value sensitive design in responsible AI toolkits
, CHI 2024, Publisher: ACMValue Sensitive Design (VSD) is a framework for integrating human values throughout the technology design process. In parallel, Responsible AI (RAI) advocates for the development of systems aligning with ethical values, such as fairness and transparency. In this study, we posit that a VSD approach is not only compatible, but also advantageous to the development of RAI toolkits. To empirically assess this hypothesis, we conducted four workshops involving 17 early-career AI researchers. Our aim was to establish links between VSD and RAI values while examining how existingtoolkits incorporate VSD principles in their design. Our findings show that collaborative and educational design features within these toolkits, including illustrative examples and open-ended cues, facilitate an understanding of human and ethical values, and empower researchers to incorporate values into AI systems. Drawing on these insights, we formulated six design guidelines for integrating VSD values into the development of RAI toolkits.
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Journal articleLi H, Gong Y, Zhou H, et al., 2024,
Author Correction: Ampere-hour-scale soft-package potassium-ion hybrid capacitors enabling 6-minute fast-charging.
, Nat Commun, Vol: 15 -
Journal articleNaylor Marlow M, Chen J, Wu B, 2024,
Degradation in parallel-connected lithium-ion battery packs under thermal gradients
, Communications Engineering, Vol: 3, ISSN: 2731-3395Practical lithium-ion battery systems require parallelisation of tens to hundreds of cells, however understanding of how pack-level thermal gradients influence lifetime performance remains a research gap. Here we present an experimental study of surface cooled parallel string battery packs (temperature range 20–45 °C), and identify two main operational modes; convergent degradation with homogeneous temperatures, and (the more detrimental) divergent degradation driven by thermal gradients. We attribute the divergent case to the, often overlooked, cathode impedance growth. This was negatively correlated with temperature and can cause positive feedback where the impedance of cells in parallel diverge over time; increasing heterogeneous current and state-of-charge distributions. These conclusions are supported by current distribution measurements, decoupled impedance measurements and degradation mode analysis. From this, mechanistic explanations are proposed, alongside a publicly available aging dataset, which highlights the critical role of capturing cathode degradation in parallel-connected batteries; a key insight for battery pack developers
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Journal articlePinkse J, Demirel P, Marino A, 2024,
Unlocking innovation for net zero: constraints, enablers, and firm-level transition strategies
, Industry and Innovation: dynamics, strategies, policies, Vol: 31, Pages: 16-41, ISSN: 1366-2716Transition pathways for net zero encompass seemingly insurmountable innovation challenges for the scaling of less mature technological solutions such as hydrogen, materials substitution, and electrification as well as societal challenges to increase the market acceptability of these solutions. In this article, we present a conceptual framework which provides a firm-level perspective on net-zero innovation which has four unique characteristics, i.e. it is complex, systemic, urgent, and directional. The framework shows that the input, process, and output constraints that incumbent firms face in the net-zero transition can be tackled through four firm-level innovation levers – i.e. recombinative, collaborative, integrative, and socio-cognitive capabilities – which, in concert, act as enablers for firms to address these net-zero constraints. We conclude the article by outlining the framework’s main insights for firms’ innovation strategies for net zero and the policy implications. We also propose avenues for future research on net-zero innovation.
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Journal articleGonzález-Toledo D, Cuevas-Rodríguez M, Vicente T, et al., 2024,
Spatial release from masking in the median plane with non-native speakers using individual and mannequin head related transfer functions.
, J Acoust Soc Am, Vol: 155, Pages: 284-293Spatial release from masking (SRM) in speech-on-speech tasks has been widely studied in the horizontal plane, where interaural cues play a fundamental role. Several studies have also observed SRM for sources located in the median plane, where (monaural) spectral cues are more important. However, a relatively unexplored research question concerns the impact of head-related transfer function (HRTF) personalisation on SRM, for example, whether using individually-measured HRTFs results in better performance if compared with the use of mannequin HRTFs. This study compares SRM in the median plane in a speech-on-speech virtual task rendered using both individual and mannequin HRTFs. SRM is obtained using English sentences with non-native English speakers. Our participants show lower SRM performances compared to those found by others using native English participants. Furthermore, SRM is significantly larger when the source is spatialised using the individual HRTF, and this effect is more marked for those with lower English proficiency. Further analyses using a spectral distortion metric and the estimation of the better-ear effect, show that the observed SRM can only partially be explained by HRTF-specific factors and that the effect of the familiarity with individual spatial cues is likely to be the most significant element driving these results.
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Journal articleXie R, Pinson P, Xu Y, et al., 2024,
Robust Generation Dispatch With Purchase of Renewable Power and Load Predictions
, IEEE Transactions on Sustainable Energy, ISSN: 1949-3029The increasing use of renewable energy sources (RESs) and responsive loads has made power systems more uncertain. Meanwhile, thanks to the development of advanced metering and forecasting technologies, predictions by RES and load owners are now attainable. Many recent studies have revealed that pooling the predictions from RESs and loads can help the operators predict more accurately and make better dispatch decisions. However, how the prediction purchase decisions are made during the dispatch processes needs further investigation. This paper fills the research gap by proposing a novel robust generation dispatch model considering the purchase and use of predictions from RESs and loads. The prediction purchase decisions are made in the first stage, which influence the accuracy of predictions from RESs and loads, and further the uncertainty set and the worst-case second-stage dispatch performance. This two-stage procedure is essentially a robust optimization problem with decision-dependent uncertainty (DDU). A mapping-based column-and-constraint generation (C&CG) algorithm is developed to overcome the potential failures of traditional solution methods in detecting feasibility, guaranteeing convergence, and reaching optimal strategies under DDU. Case studies demonstrate the effectiveness, necessity, and scalability of the proposed model and algorithm.
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Journal articlevan der Meer D, Pinson P, Camal S, et al., 2024,
CRPS-based online learning for nonlinear probabilistic forecast combination
, International Journal of Forecasting, ISSN: 0169-2070Forecast combination improves upon the component forecasts. Most often, combination approaches are restricted to the linear setting only. However, theory shows that if the component forecasts are neutrally dispersed—a requirement for probabilistic calibration—linear forecast combination will only increase dispersion and thus lead to miscalibration. Furthermore, the accuracy of the component forecasts may vary over time and the combination weights should vary accordingly, necessitating updates as time progresses. In this paper, we develop an online version of the beta-transformed linear pool, which theoretically can transform the probabilistic forecasts such that they are neutrally dispersed. We show that, in the case of stationary synthetic time series, the performance of the developed method converges to that of the optimal combination in hindsight. Moreover, in the case of nonstationary real-world time series from a wind farm in mid-west France, the developed model outperforms the optimal combination in hindsight.
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Journal articleRaja AA, Pinson P, Kazempour J, et al., 2024,
A market for trading forecasts: a wagering mechanism
, International Journal of Forecasting, Vol: 40, Pages: 142-159, ISSN: 0169-2070In many areas of industry and society, including energy, healthcare, and logistics, agents collect vast amounts of data that are deemed proprietary. These data owners extract predictive information of varying quality and relevance from data depending on quantity, inherent information content, and their own technical expertise. Aggregating these data and heterogeneous predictive skills, which are distributed in terms of ownership, can result in a higher collective value for a prediction task. In this paper, a platform for improving predictions via the implicit pooling of private information in return for possible remuneration is envisioned. Specifically, a wagering-based forecast elicitation market platform has been designed, in which a buyer intending to improve their forecasts posts a prediction task, and sellers respond to it with their forecast reports and wagers. This market delivers an aggregated forecast to the buyer (pre-event) and allocates a payoff to the sellers (post-event) for their contribution. A payoff mechanism is proposed and it is proven that it satisfies several desirable economic properties, including those specific to electronic platforms. Furthermore, the properties of the forecast aggregation operator and scoring rules are discussed in order to emphasize their effect on the sellers’ payoff. Finally, numerical examples are provided in order to illustrate the structure and properties of the proposed market platform.
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Journal articleAlmukhtar A, Batcup C, Bowman M, et al., 2024,
Barriers and facilitators to sustainable operating theatres: a systematic review using the Theoretical Domains Framework
, International Journal of Surgery, Vol: 110, Pages: 554-568, ISSN: 1743-9159Background:The health sector contributes significantly to the climate crisis. Operating theatres in particular are a major contributor of greenhouse gas emissions and waste, and while there are several evidence-based guidelines to reduce this impact, these are often not followed. We systematically reviewed the literature to identify barriers and facilitators of sustainable behaviour in operating theatres, categorising these using the TheoreticalDomains Framework (TDF).Method:Medline, Embase, PsychInfo, and Global Health databases were searched for articles published between January 2000- June 2023, using the concepts: barriers and facilitators, sustainability, and surgery. Two reviewers screened abstracts from identified studies, evaluated quality, and extracted data. Identified determinants weremapped to TDF domains and further themes as required.Findings:Twenty-one studies were selected for analysis and assessment (seventeen surveys and four interview studies) comprising 8286 participants, including surgeons, nurses and anaesthetists. Eighteen themes across ten TDF domains were identified. The mostcommon barriers to adoption of green behaviours in operating theatres were in domains of: ‘knowledge’ (N=18) e.g. knowledge of sustainable practices;‘environmental context and resources’ (N=16) e.g.‘personnel shortage and workload and inadequate recycling facilities; ‘social influences’ (N=9) e.g. lack ofleadership/organisational mandate or support; ‘beliefs about consequences’ (N=9) e.g. concerns regarding safety. Intention was the most common facilitator, with eleven studies citing it.Discussion:Despite intentions to adopt sustainable practices in operating theatres, this review identifies several barriers to doing so. Interventions should focus on mitigating these, especially by improving staff's knowledge of sustainability practices and working within the environmental context and time pressures. Furthermore, inst
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Journal articleFrölke L, Prat E, Pinson P, et al., 2024,
On the efficiency of energy markets with non-merchant storage
, Energy Systems, ISSN: 1868-3967Energy market designs with non-merchant storage have been proposed in recent years, with the aim of achieving optimal market integration of storage. In order to handle the time-linking constraints that are introduced in such markets, existing works commonly make simplifying assumptions about the end-of-horizon storage level, e.g., by imposing an exogenous level for the amount of energy to be left for the next time horizon. This work analyzes market properties under such assumptions, as well as in their absence. We find that, although they ensure cost recovery for all market participants, these assumptions generally lead to market inefficiencies. Therefore we consider the design of markets with non-merchant storage without such simplifying assumptions. Using illustrative examples, as well as detailed proofs, we provide conditions under which market prices in subsequent market horizons fail to reflect the value of stored energy. We show that this problem is essential to address in order to preserve market efficiency and cost recovery. Finally, we propose a method for restoring these market properties in a perfect-foresight setting.
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Journal articleWen H, Pinson P, Gu J, et al., 2024,
Wind energy forecasting with missing values within a fully conditional specification framework
, International Journal of Forecasting, Vol: 40, Pages: 77-95, ISSN: 0169-2070Wind power forecasting is essential to power system operation and electricity markets. As abundant data became available thanks to the deployment of measurement infrastructures and the democratization of meteorological modeling, extensive data-driven approaches have been developed within both point and probabilistic forecasting frameworks. These models usually assume that the dataset at hand is complete and overlook missing value issues that often occur in practice. In contrast to that common approach, we here rigorously consider the wind power forecasting problem in the presence of missing values, by jointly accommodating imputation and forecasting tasks. Our approach can infer the joint distribution of input features and target variables at the model estimation stage based on incomplete observations only. We place emphasis on a fully conditional specification method, owing to its desirable properties, e.g., being assumption-free when it comes to these joint distributions. Then, at the operational forecasting stage, with available features at hand, one can issue forecasts by implicitly imputing all missing entries. The approach is applicable to both point and probabilistic forecasting, while yielding competitive forecast quality in both simulated and real-world case studies. The results confirm that by using a powerful universal imputation method based on a fully conditional specification, the proposed universal imputation approach is superior to the common impute-then-predict approach, especially in the context of probabilistic forecasting.
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Journal articleWang Z, Acha S, Bird M, et al., 2024,
A total cost of ownership analysis of zero emission powertrain solutions for the heavy goods vehicle sector
, Journal of Cleaner Production, Vol: 434, ISSN: 0959-6526Transport-related activities represented 34% of the total carbon emissions in the UK in 2022 and heavy-duty vehicles (HGVs) accounted for one-fifth of the road transport greenhouse gas (GHG) emissions. Currently, battery electric vehicles (BEVs) and hydrogen fuel cell electric vehicles (FCEVs) are considered as suitable replacements for diesel fleets. However, these technologies continue to face techno-economic barriers, creating uncertainty for fleet operators wanting to transition away from diesel-powered internal combustion engine vehicles (ICEVs). This paper assesses the performance and cost competitiveness of BEV and FCEV powertrain solutions in the hard-to-abate HGV sector. The study evaluates the impact of battery degradation and a carbon tax on the cost of owning the vehicles. An integrated total cost of ownership (TCO) model, which includes these factors for the first time, is developed to study a large retailer's HGV fleet operating in the UK. The modelling framework compares the capital expenditures (CAPEX) and operating expenses (OPEX) of alternative technologies against ICEVs. The TCO of BEVs and FCEVs are 11% to 33% and 37% to 78% higher than ICEVs; respectively. Despite these differences, by adopting a longer lifetime for the vehicle it can effectively narrow the cost gap. Alternatively, cost parity with ICEVs could be achieved if BEV battery cost reduces by 56% or if FCEV fuel cell cost reduces by 60%. Besides, the pivot point for hydrogen price is determined at £2.5 per kg. The findings suggest that BEV is closer to market as its TCO value is becoming competitive, whereas FCEV provides a more viable solution than BEV for long-haul applications due to shorter refuelling time and lower load capacity penalties. Furthermore, degradation of performance in lithium-ion batteries is found to have a minor impact on TCO if battery replacement is not required. However, critical component replacement and warranty can influence commercial viability. Given
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Journal articleFerraro P, Penzkofer A, King C, et al., 2024,
Feedback control for distributed ledgers: An attack mitigation policy for DAG-based DLTs
, IEEE Transactions on Automatic Control, Pages: 1-8, ISSN: 0018-9286 -
Journal articleZhao L, Ferraro P, Shorten R, 2024,
A smart mask to enforce social contracts based on IOTA Tangle.
, PLoS One, Vol: 19In this paper we present the design for a smart-mask to mitigate the impact of an airborne virus such as COVID-19. The design utilises recent results from feedback control theory over a distributed ledger that have been developed to enforce compliance in a pseudo-anonymous manner. The design is based on the use of the IOTA distributed ledger. A hardware-in-the-loop simulation based on indoor positioning, paired with Monte-Carlo simulations, is developed to demonstrate the efficacy of the designed prototype.
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Journal articleSadan MK, Lian GJ, Smith RM, et al., 2023,
Co, Ni-free ultrathick free-standing dry electrodes for sustainable lithium-ion batteries
, ACS Applied Energy Materials, Vol: 6, Pages: 12166-12171, ISSN: 2574-0962The conventional method of manufacturing lithium-ion battery electrodes employs a complex slurry casting process with solvents that are not environmentally friendly and process parameters that are often difficult to control. This study explores a solvent-free dry electrode fabrication process of Co- and Ni-free LiMn2O4 (LMO) cathodes using a fibrillated polymer, polytetrafluoroethylene (PTFE). A thick, dry electrode (265–368 μm, 30–64 mg cm–2) of LMO cathode was prepared successfully for the first time. Altering the conductive additives in the LMO dry electrode revealed multiwalled carbon nanotubes (CNTs) as the best conducting agent for dry electrode formulation in terms of conductivity and rate performance. Additionally, an all-dry electrode full cell consisting of both a dry electrode cathode (LMO) and an anode (LTO) delivered a stable cycling performance with a capacity retention of 82.8% after 200 cycles, demonstrating the scope for all-dry electrode full cells for future applications.
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Journal articlePan Y, Ruan H, Regmi YN, et al., 2023,
A Machine Learning Accelerated Hierarchical 3D+1D Model for Proton Exchange Membrane Fuel Cells
, ECS Meeting Abstracts, Vol: MA2023-02, Pages: 1706-1706<jats:p> Physics-based continuum models for proton exchange membrane fuel cells (PEMFCs) are an essential tool for fuel cell design and management. To date, many continuum models, ranging from 1D to 3D, have been developed for PEMFCs. Although computationally efficient, 1D models do not account for heterogeneity in flow fields, which negatively impact their accuracy. In contrast, 2D and 3D models are usually more representative of actual operating conditions but computationally intensive due to the coupled partial differential equations and large number of mesh elements involved. To overcome these issues, a hierarchical approach that combines a 2D/3D description of flow fields, gas diffusion layers (GDLs) and a simplified microporous layer (MPL)/catalyst layer (CL)/membrane sub-model has been proposed in the literature. However, studies based on this method often use a simplified or 0D MPL/CL/membrane sub-model, whose results may deviate from a full 1D description due to the neglected nonlinearity, especially at higher loads.</jats:p> <jats:p>In this study, we present a computationally efficient 3D+1D hierarchical model for PEMFCs accelerated by machine learning. The 3D model, which captures the two-phase flow in the gas channels and GDLs, is coupled with a full 1D description of the MPLs, membrane, CLs, and CL agglomerates by exchanging boundary values and fluxes, as shown in the figure. To avoid the high computing cost increase associated with the full 1D description, we develop a physics-informed neural network to replace the 1D sub-model for coupling with the 3D model, while maintaining the full description of fuel cell internal states. Large synthetic datasets are generated using the 1D model for training the neural network, ensuring the accuracy of the model. The proposed 3D+1D model is validated against experimentally obtained polarization curves and high frequency resistances under different relative humidities. The proposed
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Journal articleGovey-Scotland J, Johnstone L, Myant C, et al., 2023,
Towards a skin-on-a-chip for screening the dermal absorption of cosmetics
, Lab on a Chip: miniaturisation for chemistry, physics, biology, materials science and bioengineering, Vol: 23, Pages: 5068-5080, ISSN: 1473-0189Over the past few decades, there have been increasing global efforts to limit or ban the use of animals for testing cosmetic products. This ambition has been at the heart of international endeavours to develop new in vitro and animal-free approaches for assessing the safety of cosmetics. While several of these new approach methodologies (NAMs) have been approved for assessing different toxicological endpoints in the UK and across the EU, there remains an absence of animal-free methods for screening for dermal absorption; a measure that assesses the degree to which chemical substances can become systemically available through contact with human skin. Here, we identify some of the major technical barriers that have impacted regulatory recognition of an in vitro skin model for this purpose and propose how these could be overcome on-chip using artificial cells engineered from the bottom-up. As part of our future perspective, we suggest how this could be realised using a digital biomanufacturing pipeline that connects the design, microfluidic generation and 3D printing of artificial cells into user-crafted synthetic tissues. We highlight milestone achievements towards this goal, identify future challenges, and suggest how the ability to engineer animal-free skin models could have significant long-term consequences for dermal absorption screening, as well as for other applications.
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Journal articleMorley JD, George C, Hadler K, et al., 2023,
Crystallography of active particles defining battery electrochemistry
, Advanced Energy Materials, ISSN: 1614-6832Crystallographic features of battery active particles impose an inherent limitation on their electrochemical figures of merit namely capacity, roundtrip efficiency, longevity, safety, and recyclability. Therefore, crystallographic properties of these particles are increasingly measured not only to clarify the principal pathways by which they store and release charge but to realize the full potential of batteries. Here, state-of-the-art advances in Li+, K+, and Na+ chemistries are reviewed to reiterate the links between crystallography variations and battery electrochemical trends. These manifest at different length scales and are accompanied by a multiplicity of processes such as doping, cation disorder, directional crystal growth and extra redox. In light of this, an emphasis is placed on the need for more accurate correlations between crystallographic structure and battery electrochemistry in order to harness crystallographic beneficiation into electrode material design and manufacture, translating into high-performance and safe energy storage solutions.
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Journal articleYasin L, Atkinson A, Cooper SJ, et al., 2023,
Identifiability of the mechanisms governing the reaction kinetics of MIEC electrodes in solid oxide cells
, Electrochimica Acta, Vol: 472, ISSN: 0013-4686The oxygen reduction reaction (ORR) is the main phenomenon occurring in mixed ionic and electronic conductors (MIECs) used as air electrodes in solid oxide cells. Their optimisation requires the identification of the ORR regime, which is typically performed via electrochemical impedance spectroscopy (EIS). In this study we present a physics-based model to simulate the impedance spectra of p-type oxygen-deficient perovskite MIEC materials. The EIS response of four extreme kinetic scenarios, characterised by the rate-determining step (electron-transfer or ion-transfer) and the high/low surface coverage of adsorbed oxygen, is mechanistically interpreted for both dense films and porous electrodes. A strategy for kinetic identification is proposed based on distinctive EIS fingerprints at different oxygen partial pressures (pO2) and cathodic bias. However, distinguishing the kinetic scenarios is not free from ambiguity even in dense films since some scenarios are discriminated only via a quantitative analysis, which may be susceptible to experimental errors in real measurements, and reverse behaviours appear when combining cathodic bias with pO2 variation. More difficulties arise in porous electrodes since bulk oxygen vacancy transport interacts with the ORR response. Application of the proposed strategy using literature data for some common MIEC materials shows the typical challenges of kinetic identification when relying solely on EIS.
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Journal articleBigestans D, Cardin M-A, Kazantzis N, 2023,
Economic performance evaluation of flexible centralised and decentralised blue hydrogen production systems design under uncertainty
, Applied Energy, Vol: 352, ISSN: 0306-2619Blue hydrogen is viewed as an important energy vector in a decarbonised global economy, but its large-scale and capital-intensive production displays economic performance vulnerabities in the face of increased market and regulatory uncertainty. This study analyses flexible (modular) blue hydrogen production plant designs and evaluates their effectiveness to enhance economic performance under uncertainty. The novelty of this work lies in the development of a comprehensive techno-economic evaluation framework that considers flexible centralised and decentralised blue hydrogen plant design alternatives in the presence of irreducible uncertainty, whilst explicitly considering the time value of money, economies of scale and learning effects. A case study of centralised and decentralised blue hydrogen production for the transport sector in the San Francisco area is developed to highlight the underlying value of flexibility. The proposed methodological framework considers various blue hydrogen plant designs (fixed, phased, and flexible) and compares them using relevant economic indicators (net present value (NPV), capex, value-at-risk/gain, etc.) through a detailed Monte Carlo simulation framework. Results indicate that flexible centralised hydrogen production yields greater economic value than alternative designs, despite the associated cost-premium of modularity. It is also shown that the value of flexibility increases under greater uncertainty, higher learning rates and weaker economies of scale. Moreover, sensitivity analysis reveals that flexible design remains the preferred investment option over a wide range of market and regulatory conditions except for high initial hydrogen demand. Finally, this study demonstrates that major regulatory and market uncertainties surrounding blue hydrogen production can be effectively managed through the application of flexible engineering system design that protects the investment from major downside risks whilst allowing access to
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Journal articleBonkile MP, Jiang Y, Kirkaldy N, et al., 2023,
Coupled electrochemical-thermal-mechanical stress modelling in composite silicon/graphite lithium-ion battery electrodes
, Journal of Energy Storage, Vol: 73, ISSN: 2352-152XSilicon is often added to graphite battery electrodes to enhance the electrode-specific capacity, but it undergoes significant volume changes during (de)lithiation, which results in mechanical stress, fracture, and performance degradation. To develop long-lasting and energy-dense batteries, it is critical to understand the non-linear stress behaviour in composite silicon-graphite electrodes. In this study, we developed a coupled electrochemical-thermal-mechanical model of a composite silicon/graphite electrode in PyBaMM (an open-source physics-based modelling platform). The model is experimentally validated against a commercially available LGM50T battery, and the effects of C-rates, depth-of-discharge (DoD), and temperature are investigated. The developed model can reproduce the voltage hysteresis from the silicon and provide insights into the stress response and crack growth/propagation in the two different phases. The stress in the silicon is relatively low at low DoD but rapidly increases at a DoD >~80%, whereas the stress in the graphite increases with decreasing temperature and DoD. At higher C-rates, peak stress in the graphite increases as expected, however, this decreases for silicon due to voltage cut-offs being hit earlier, leading to lower active material utilisation since silicon is mostly active at high DoD. Therefore, this work provides an improved understanding of stress evolution in composite silicon/graphite lithium-ion batteries.
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Journal articleYi Y, Demirel P, 2023,
The impact of sustainability-oriented dynamic capabilities on firm growth: investigating the green supply chain management and green political capabilities
, Business Strategy and the Environment, Vol: 32, Pages: 5873-5888, ISSN: 0964-4733Building on the dynamic capabilities literature and natural-resource-based view, the paper examines whether firms can attain sales growth through a range of sustainability-oriented dynamic capabilities including (1) internal green supply chain management capabilities, (2) external green supply chain management capabilities and (3) green political capabilities. Based on a dataset of 277 public US firms between 2010 and 2020, a panel quantile model of firm growth showcases that while internal green supply chain capabilities and green political capabilities affect firms' growth performance positively, external green supply chain capabilities are associated with slower growth. Importantly, the results indicate that the positive growth effects of green political capabilities are short-lived, while those of internal green supply chain capabilities are long-lived. The study contributes to the sustainability-oriented dynamic capabilities literature by showing that different capabilities have different implications for firm growth depending on the firm's base performance and the time periods under consideration.
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Journal articleSadek M, Calvo R, Mougenot C, 2023,
Co-designing conversational agents: a comprehensive review and recommendations for best practices
, Design Studies, Vol: 89, ISSN: 0142-694XThis paper presents a comprehensive review of fifty-two studies co-designing conversational agents (CAs). Its objectives are to synthesise prior CA co-design efforts and provide actionable recommendations for future endeavours in CA co-design. The review systematically evaluates studies' methodological and contextual aspects, revealing trends and limitations. These insights converge into practical recommendations for co-designing CAs, including (1) selecting the most suitable design technique aligned with desired CA outcomes, (2) advocating continuous stakeholder involvement throughout the design process, and (3) emphasising the elicitation and embodiment of stakeholder values to ensure CA designs align with their perspectives. This paper contributes to standardising and enhancing co-design practices, promising to improve the quality of outcomes in the case of CAs while benefiting stakeholders and users.
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Journal articleMiguel Angel M, Pinson P, Kazempour J, 2023,
Online decision making for trading wind energy
, Computational Management Science, Vol: 20, Pages: 1-31, ISSN: 1619-697XWe propose and develop a new algorithm for trading wind energy in electricity markets, within an online learning and optimization framework. In particular, we combine a component-wise adaptive variant of the gradient descent algorithm with recent advances in the feature-driven newsvendor model. This results in an online offering approach capable of leveraging data-rich environments, while adapting to the nonstationary characteristics of energy generation and electricity markets, also with a minimal computational burden. The performance of our approach is analyzed based on several numerical experiments, showing both better adaptability to nonstationary uncertain parameters and significant economic gains.
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Journal articleRatcliffe E, Baxter W, Aurisicchio M, et al., 2023,
The role of ritual communication in consumption: A consumer coffee experience
, International Journal of Food Design, ISSN: 2056-6522<jats:p>Rituals are part of the consumer experience of goods, especially food and drink, and can contribute to consumer enjoyment of and fidelity to a specific product. However, we lack detailed description of food/beverage-related rituals and their potential impact on consumer perceptions, in particular whether and how communicating those rituals to consumers influences their attitudes. Here we use coffee as an example of a ritualized product within the UK market to explore this potential relationship and identify opportunities for design. In Study 1, we identified rituals associated with coffee preparation and consumption. In Study 2, we found that several procedural aspects of the rituals identified in Study 1 were not consistently conveyed in coffee advertising, indicating a potential gap in communication with consumers. In Study 3, we showed that communicating such rituals to consumers resulted in significantly greater willingness to pay for coffee, mediated by perceptions of social attention. This work connects growing interest in the psychological mechanisms of ritual with work on consumer perceptions and behaviour and carries significant implications for the design of messaging around food experience.</jats:p>
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Journal articleSadek M, Calvo R, Mougenot C, 2023,
Designing value-sensitive AI: a critical review and recommendations for socio-technical design processes
, AI and Ethics, ISSN: 2730-5961This paper presents a critical review of how different socio-technical design processes for AI-based systems, from scholarly works and industry, support the creation of value-sensitive AI (VSAI). The review contributes to the emerging field of human-centred AI, and the even more embryonic space of VSAI in four ways: (i) it introduces three criteria for the review of VSAI based on their contribution to design processes’ overall value-sensitivity, and as a response to criticisms that current interventions are lacking in these aspects: comprehensiveness, level of guidance offered, and methodological value-sensitivity, (ii) it provides a novel review of socio-technical design processes for AI-based systems, (iii) it assesses each process based on the mentioned criteria and synthesises the results into broader trends, and (iv) it offers a resulting set of recommendations for the design of VSAI. The objective of the paper is to help creators and followers of design processes—whether scholarly or industry-based—to understand the level of value-sensitivity offered by different socio-technical design processes and act accordingly based on their needs: to adopt or adapt existing processes or to create new ones.
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Conference paperWang E, Davis J, Moro D, et al., 2023,
Enabling Binary Neural Network Training on the Edge
, Workshop on Binary Networks for Computer Vision -
Journal articleChappell D, Bello F, Kormushev P, et al., 2023,
The hydra hand: a mode-switching underactuated gripper with precision and power grasping modes
, IEEE Robotics and Automation Letters, Vol: 8, Pages: 7599-7606, ISSN: 2377-3766Human hands are able to grasp a wide range of object sizes, shapes, and weights, achieved via reshaping and altering their apparent grasping stiffness between compliant power and rigid precision. Achieving similar versatility in robotic hands remains a challenge, which has often been addressed by adding extra controllable degrees of freedom, tactile sensors, or specialised extra grasping hardware, at the cost of control complexity and robustness. We introduce a novel reconfigurable four-fingered two-actuator underactuated gripper—the Hydra Hand—that switches between compliant power and rigid precision grasps using a single motor, while generating grasps via a single hydraulic actuator—exhibiting adaptive grasping between finger pairs, enabling the power grasping of two objects simultaneously. The mode switching mechanism and the hand's kinematics are presented and analysed, and performance is tested on two grasping benchmarks: one focused on rigid objects, and the other on items of clothing. The Hydra Hand is shown to excel at grasping large and irregular objects, and small objects with its respective compliant power and rigid precision configurations. The hand's versatility is then showcased by executing the challenging manipulation task of safely grasping and placing a bunch of grapes, and then plucking a single grape from the bunch.
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Conference paperWhitby MA, Iacovides I, Deterding S, 2023,
“Conversations with pigeons”: capturing players’ lived experience of perspective challenging games
, CHI PLAY 2023, Publisher: Association for Computing Machinery (ACM), Pages: 833-855, ISSN: 2573-0142Video games are increasingly designed to provoke reflection and challenge players’ perspectives. Yet we know little about how such perspective-challenging experiences come about in gameplay. In response, we used systematic self-observation diaries and micro-phenomenological interviews to capture players’ (n=15) lived experience of perspective challenges in purposely sampled games including Hatoful Boyfriend, The Stanley Parable, or Papers, Please. We found a sequence of trigger, reflection, and transformation constituting perspective-challenging experiences, matching Mezirow’s model of transformative learning. Most of these were game-related or ‘endo-game’, suggesting that medium self-reflection could be an overlooked part of everyday game reflection and appreciation. Reflections were accompanied by a wide range of emotions, including frequent epistemic emotions, and emotions could change drastically even during short gameplay experiences. Actual perspective change or transformation was rare. We construct a model of granular types of triggers, reflections, and transformations that can aid reflective game design.
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