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Reliability Assessment of IoT-enabled Systems using Fault Trees and Bayesian Networks
No full textNoThe Internet of Things (IoT) has brought significant advancements in various domains, providing innovative and efficient solutions. However, ensuring the safe design and operation of IoT devices is
crucial, as the consequences of component failure can range from system
downtime to dangerous operating states. Several methods have been proposed to evaluate the failure behaviours of IoT-based systems, including
Fault Tree Analysis (FTA), a methodology adopted from other safetycritical domains. This study integrated FTA and Bayesian Network (BN)
models to assess IoT system reliability based on components' reliability
data and other statistical information. The integrated model achieved
efficient predictive failure analysis, considering combinations of 12 basic
events to quantify the overall system's reliability. The model also enables
criticality analysis, ranking basic events based on their contributions to
system failure and providing a guide for design modification in order to
enhance IoT safety. By comparing failure data in FTA and criticality
indices obtained using the BN model, the proposed integration offers a
probabilistic estimation of IoT system failure and a viable safety guide
for designing IoT systems
Electrocatalytic reactors for syngas production from natural gas
No full textNoThe emission of greenhouse gases on a global scale is predominantly caused by the utilization of fossil fuels. Various methods have been explored to address the recycling of CO2, which among, the CO2 conversion into high-value chemicals become so promising.
The purpose of this book chapter evaluation is CO2 reduction and H2 evolution reactions for producing syngas. A comprehensive analysis shall highlight (i) the technical advantages and impediments of various reactor classifications, (ii) the effect of electrolytes on electrolyzers in the liquid phase, and (iv) the catalysts that are viable for the creation of important products such as CO
Statistical arbitrage: Factor investing approach
Get PDFYesWe introduce a continuous time model for stock prices in a general factor representation with the noise driven by a geometric Brownian motion process. We derive the theoretical hitting probability distribution for the long-until-barrier strategies and the conditions for statistical arbitrage. We optimize our statistical arbitrage strategies with respect to the expected discounted returns and the Sharpe ratio. Bootstrapping results show that the theoretical hitting probability distribution is a realistic representation of the empirical hitting probabilities. We test the empirical performance of the long-until-barrier strategies using US equities and demonstrate that our trading rules can generate statistical arbitrage profits
Strategy Creation Behaviour and ‘Last Gasp’ Digitalisation as Predictors of Sales Performance and Cash Flow
Get PDFYesPurpose - Although recent literature has examined diverse measures adopted by SMEs to navigate the COVID-19 turbulence, there is a shortage of evidence on how crisis-time strategy creation behaviour and digitalization activities increase (1) sales and (2) cash flow. Thus, predicated on novel strategy creation perspective, this inquiry investigates the crisis behaviour, sales and cash flow performance of 528 SMEs in Morocco. Design/Methodology/Approach - Novel links between (1) aggregate wage cuts, (2) variable operating hours, (3) deferred payment to suppliers, (4) deferred payment to tax authorities and (5) sales performance are developed and tested. A further link between sales performance and cash flow is also examined and the analysis is performed using a non-linear structural equation modelling technique. Findings - While there is a significant association between the strategy creation behaviours and sales performance, only variable operating hours have a positive effect. Also, sales performance increases cash flow and this relationship is substantially strengthened by e-commerce digitalization and innovation. Originality/Value – Theoretically, this is one of the first inquiries to espouse the strategy creation view to explain SMEs’ crisis-time behaviour and digitalization. For practical use, to supplement Moroccan SMEs’ propensity to seek tax deferrals, it is argued that debt and equity support measures are also needed to boost sales performance and cash flow
Effect of myopia management contact lens design on accommodative microfluctuations and eye movements during reading
Get PDFYesBackground: Soft contact lenses have been developed and licensed for reducing myopia progression. These lenses
have different designs, such as extended depth of focus (EDOF) and dual focus (DF). In this prospective, doublemasked, cross-over study, different lens designs were investigated to see whether these had impact on accommodative microfluctuations and eye movements during reading.
Methods: Participants were fitted with three lenses in a randomised order; a single vision (SV) design (Omafilcon
A2; Proclear), a DF design (Omafilcon A2; MiSight), and an EDOF lens design (Etafilcon A; NaturalVue),.
Accommodative microfluctuations were measured at 25 cm for at least 60s in each lens, using a Shin-Nippon
SRW-5000 autorefractor adapted to continuously record accommodation at 22Hz. Eye movement data was
collected with the Thomson Clinical Eye Tracker incorporating a Tobii Eye bar. Eye movements include fixations
per row, fixations per minute, mean regressions per row, total number of regressions, and total rightward saccades. Accommodation data was analysed using power spectrum analysis. Differences between the lenses were
compared using a related sample two-way Friedman test.
Results: Twenty-three participants (18–29 years) were recruited to take part. The average mean spherical error
was − 2.65D ± 1.42DS, with an average age of 23.4 ± 3.5 years. No significant difference for accommodative
microfluctuations was found. Significant differences were found for fixations per row (P = 0.03), fixations per
minute (P = 0.008), mean regressions per row (P = 0.002), and total number of regressions (P = 0.002), but not
total rightward saccades (P = 0.10). Post-hoc analysis indicated the EDOF lens results were significantly different
from the other lenses, with more regressive eye movements observed.
Conclusions: Regressive saccades appear to increase when wearing EDOF lens designs, which may impact visual
comfort. Further studies in children, over a longer period of adaptation are necessary to assess the potential
impact of this finding on daily reading activities in children.This project was supported by the British Contact Lens Association Summer Studentship Award (recipient Muskaan Hussain)
A model learning based testing approach for kernel P systems
Get PDFYesKernel P systems have been introduced as a unifying formalism allowing to specify, simulate and analyse various problems. Several applications of this
model have been considered and a powerful tool built in order to support their development and analysis. Testing represents an important aspect of any system analysis and correctness. In this paper we introduce for the first time a bounded test generation approach for kernel P systems by considering bounded input sequences. A learning algorithm for kernel P systems is based on learning X-machine models that are equivalent to these systems for sequences of steps up to a certain limit, ℓ. The Lℓ learning algorithm is used.
The testing approach is then devised from the inferred X-machines. The method is applied to a case study illustrating the key parts of the approach.This research was supported by the European Regional Development Fund, Competitiveness Operational Program 2014-2020 through project IDBC (code SMIS 2014+: 121512). Raluca Lefticaru, Savas Konur and Marian Gheorghe have been partially supported by the Royal Society grant IES╲R3╲213176, 2022-2024. The work of Savas Konur is also supported by EPSRC (EP/R043787/1)
Women’s Informal Entrepreneurship through the Lens of Institutional Voids and Institutional Logics
Get PDFYesIn this conceptual paper, we respond to the calls for broader theoretical approaches that can coherently demonstrate a high degree of conceptual sensitivity to multiple combinations of institutional factors influencing women's informal entrepreneurship (WIE) and related agency. We do so by integrating constructs of gender and gender inequality with those of institutional logics and institutional voids. We find that a refined understanding of institutional voids is required to pave the way for a meaningful theoretical integration and empirical application of the related conceptualizations. We offer such a revised definition by placing formal and informal logics (rather than institutions) at the heart of it. In our theorizing, we propose that gender interplaying with formal and informal institutional logics create varying degrees of obscure and unique institutional voids that shape WIE prevalence. The proposed harmonized theoretical lens provides researchers with flexible yet consistent guidance for conducting context-specific empirical work that can coherently advance understanding of underlying logics shaping WIE and related agency.Research Development Fund Publication Prize Award winner, Jan 2023
Child and family experiences of a whole-systems approach to physical activity in a multiethnic UK city: a citizen science evaluation protocol
Get PDFYesWhole-systems approaches are being adopted to tackle physical inactivity. The mechanisms contributing to changes resulting from whole-systems approaches are not fully understood. The voices of children and families that these approaches are designed for need to be heard to understand what is working, for whom, where and in what context. This paper describes the protocol for the children and families' citizen science evaluation of the Join Us: Move, Play (JU:MP) programme, a whole-systems approach to increasing physical activity in children and young people aged 5-14 years in Bradford, UK.
The evaluation aims to understand the lived experiences of children and families' relationship with physical activity and participation in the JU:MP programme. The study takes a collaborative and contributory citizen science approach, including focus groups, parent-child dyad interviews and participatory research. Feedback and data will guide changes within this study and the JU:MP programme. We also aim to examine participant experience of citizen science and the suitability of a citizen science approach to evaluate a whole-systems approach. Data will be analysed using framework approach alongside iterative analysis with and by citizen scientists in the collaborative citizen science study.
Ethical approval has been granted by the University of Bradford: study one (E891-focus groups as part of the control trial, E982-parent-child dyad interviews) and study two (E992). Results will be published in peer-reviewed journals and summaries will be provided to the participants, through schools or directly. The citizen scientists will provide input to create further dissemination opportunities
Extending the Merton model with applications to credit value adjustment
Get PDFYesFollowing the global financial crisis, the measurement of counterparty credit risk has become
an essential part of the Basel III accord with credit value adjustment being one of the most
prominent components of this concept. In this study, we extend the Merton structural credit
risk model for counterparty credit risk calculation in the context of calculating the credit value
adjustment mainly by estimating the probability of default. We improve the Merton model in a
variance-convoluted-gamma environment to include default dependence between counterparties
through a linear factor decomposition framework. This allows one to tackle dependence through
a systematic common component. Our set-up allows for easier, faster and more accurate fitting
for the credit spread. Results confirm that use of the variance-gamma-convolution clearly solves
the vanishing credit spread problem for short time-to-maturity or low leverage cases compared
to a Brownian motion environment and its modifications.Ahmet Sensoy gratefully acknowledges support from Turkish Academy of Sciences under its Outstanding
Young Scientist Award Programme (TUBA-GEBIP). Frank J. Fabozzi acknowledges the financial support
from EDHEC Business School
The AU and Issues of Institutional Capacity and Enforcement
Get PDFYesIn light of the emerging African Union (AU) legal order, this chapter examines AU’s institutions and courts to situate AU law in the wider context of AU’s enforcement mechanisms. In the nearly two decades of the operational phase of the AU, several institutions and courts have arguably ensured enforcements of its laws, policies, and decisions. Added to its judicial, human rights, and legal organs, the African Court of Human Rights has been at the disposal of the AU in the fight against human rights abuses and implementation of regional and international instruments in environmental and criminal law matters. What could potentially be the impact of these institutions on AU law? Also, will the evolving AU law require a separate enforcement mechanism, or could it rely on pre-existing institutions and courts? These issues become necessary in view of the AU’s commitment to implement Aspiration 3 of Agenda 2063, which amongst other things, envisions respect for human rights, justice, and the rule of law within the region. The chapter argues that the challenges of weak institutions, corruption, and internal conflicts are endemic within the continent. Therefore, it takes the view that a system of normative, cultural, and cognitive institutional reforms and transformation will be valuable