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Saturation estimation with complex electrical conductivity for hydrate-bearing clayey sediments: an experimental study
Get PDFClays have considerable influence on the electrical properties of hydrate-bearing sediments. It is desirable to understand the electrical properties of hydrate-bearing clayey sediments and to build hydrate saturation (Sh) models for reservoir evaluation and monitoring. The electrical properties of tetrahydrofuran-hydrate-bearing sediments with montmorillonite are characterized by complex conductivity at frequencies from 0.01 Hz to 1 kHz. The effects of clay and Sh on the complex conductivity were analyzed. A decrease and increase in electrical conductance result from the clay-swelling-induced blockage and ion migration in the electrical double layer (EDL), respectively. The quadrature conductivity increases with the clay content up to 10% because of the increased surface site density of counterions in EDL. Both the in-phase conductivity and quadrature conductivity decrease consistently with increasing Sh from 0.50 to 0.90. Three sets of models for Sh evaluation were developed. The model based on the Simandoux equation outperforms Archie’s formula, with a root-mean-square error (ERMS) of 1.8% and 3.9%, respectively, highlighting the clay effects on the in-phase conductivity. The frequency effect correlations based on in-phase and quadrature conductivities exhibit inferior performance (ERMS = 11.6% and 13.2%, respectively) due to the challenge of choosing an appropriate pair of frequencies and intrinsic uncertainties from two measurements. The second-order Cole-Cole formula can be used to fit the complex-conductivity spectra. One pair of inverted Cole-Cole parameters, i.e., characteristic time and chargeability, is employed to predict Sh with an ERMS of 5.05% and 9.05%, respectively.Journal of Ocean University of China (English Edition
Impacts of long-term application of best management practices on yields and root carbohydrate content in asparagus (Asparagus officinalis) (UK)
Get PDFYield physiology of asparagus (Asparagus officinalis L.) is strongly influenced by biotic factors such as crown and root rot caused by Fusarium spp. and by abiotic conditions such as precipitation or temperatures, duration of each harvest, and field management practices. Asparagus yields are linked to the availability of soluble carbohydrates (CHO) in the storage root system which is considered a key factor in asparagus productivity. The aim of this study was to quantify the impacts of the long-term application of a range of potential Best Management Practices (BMPs) on yield and storage root carbohydrate content in green asparagus in a long-term field trial. The trial was established in 2016 with the asparagus ‘Gijnlim’ variety. Commercial yields were collected in 2018, 2019 and 2020. Root carbohydrate content was determined in 2019 and 2020. BMPs included (1) companion crops - Rye (Secale cereale L.), Mustard (Sinapis alba L.), (2) interrow surface mulch applications of either straw mulch or PAS 100 compost (Publicly available specification) in combination with shallow soil disturbance (SSD), (3) the conventional practice and modifications of the conventional tillage practice by applying SSD or not applying SSD and (4) a zero-tillage option. Annual re-ridging (R) and not ridging (NR) were applied to BMP options 1–3. SSD had no significant impact on asparagus yields while annual re-ridging negatively affected total yields of treatments with bare soil interrows, which were managed without SSD. Conventional practice was associated with a 22% yield reduction and ∼€4250 ha−1 annual loss in potential revenue as compared to the Zero-tillage treatment. Companion cropping with mustard did not have a significant impact on asparagus yields. Rye without annual re-ridging was however associated with yield reductions of > 20% as compared to the Conventional practice. PAS 100 Compost applied in asparagus interrows (at 25 t ha−1 per year) in combination with SSD without annual re-ridging resulted in improvements to yields of 20%, 10% and 34% in 2018, 2019 and 2020, respectively, as compared to the Conventional practice. No correlation was observed between storage root soluble carbohydrate content and asparagus yields. The results of this study confirmed that asparagus yield, and thus total farm income can be significantly improved through implementation of several of the BMPs investigated.Agriculture and Horticulture Development Board (Project FV450a and FV450b)European Journal of Agronom
Eco-social sustainability assessment of manufacturing systems: an LCA-based framework
Get PDFIn this paper, model-based sustainability assessment framework with social impact considerations is developed. The framework integrates the stochastic, nonlinear, and complex interrelationships that characterize most manufacturing systems, and incorporates their impact in the sustainability assessment module. The framework consists of three models that run successively, namely: stochastic discrete-event simulation (DES) model, environmental lifecycle assessment (LCA) and social LCA models. To test and validate the model, and to demonstrate its applicability and usefulness in industrial settings, a case study on the environmental and social impacts associated with the manufacturing of an aerospace component is carried out. Results revealed that integrating the stochastic behaviour of production systems can unveil production issues that are likely to arise at the strategic level and affect the sustainability performance, while not being instantly perceptible. Social LCA indicated that, although input data suffered from quality issues, there is a potential higher risk associated with overseas upstream supply chains. This risk can, however, be potentially mitigated through technology-based enhanced traceability and transparency of upstream supply chains, or even the localization of upstream activities, where possible.UKRI ATI programme: 10304030th CIRP Life Cycle Engineering Conference 2023Procedia CIR
Simple internal model-based robust control design for a non-minimum phase unmanned aerial vehicle
Get PDFRobust control has been successful in enabling flight stability and performance for UAVs. This paper presents a simple explainable robust control design for UAV platforms with non-minimum phase (NMP) zero characteristics in their model. The paper contributes to economic (simple) robust control design by addressing the NMP model’s characteristics via Internal Model Control (IMC) and its impact on the UAV pitch response performance. The proposed design is compared with a Parallel Feedback Control Design (PFCD) scheme for the same vehicle platform, for fair comparison. Simulation results illustrate the achievement of the proposed control designs for the UAV platform; only the pitch control is addressed. A by-product of this work is the interpretation of different ways of manipulating the non-minimum phase plant model, so-called ‘modelling for control’, to enable the simple controller design. The work in this paper underpins the simplicity and robustness of the IMC technique for the NMP UAV platform, which further supports the explainability of the control structure relative to performance.Machine
A Loewner-based system identification and structural health monitoring approach for mechanical systems
Get PDFData-driven structural health monitoring (SHM) requires precise estimates of the target system behaviour. In this sense, SHM by means of modal parameters is strictly linked to system identifcation (SI). However, existing frequency-domain SI techniques have several theoretical and practical drawbacks. This paper proposes using an input-output system identifcation technique based on rational interpolation, known as the Loewner framework (LF), to estimate the modal properties of mechanical systems. Pioneeringly, the Loewner framework mode shapes and natural frequencies estimated by LF are then applied as damage-sensitive features for damage detection. To assess its capability, the Loewner framework is validated on both numerical and experimental datasets and compared to established system identification techniques. Promising results are achieved in terms of accuracy and reliability.Engineering and Physical Sciences Research Council (EPSRC): 2277626Structural Control and Health Monitorin
Human resource management in the age of generative artificial intelligence: perspectives and research directions on ChatGPT
Get PDFChatGPT and its variants that use generative artificial intelligence (AI) models have rapidly become a focal point in academic and media discussions about their potential benefits and drawbacks across various sectors of the economy, democracy, society, and environment. It remains unclear whether these technologies result in job displacement or creation, or if they merely shift human labour by generating new, potentially trivial or practically irrelevant, information and decisions. According to the CEO of ChatGPT, the potential impact of this new family of AI technology could be as big as “the printing press”, with significant implications for employment, stakeholder relationships, business models, and academic research, and its full consequences are largely undiscovered and uncertain. The introduction of more advanced and potent generative AI tools in the AI market, following the launch of ChatGPT, has ramped up the “AI arms race”, creating continuing uncertainty for workers, expanding their business applications, while heightening risks related to well-being, bias, misinformation, context insensitivity, privacy issues, ethical dilemmas, and security. Given these developments, this perspectives editorial offers a collection of perspectives and research pathways to extend HRM scholarship in the realm of generative AI. In doing so, the discussion synthesizes the literature on AI and generative AI, connecting it to various aspects of HRM processes, practices, relationships, and outcomes, thereby contributing to shaping the future of HRM research
PANACEA: an automated misinformation detection system on COVID-19
Get PDFIn this demo, we introduce a web-based misinformation detection system PANACEA on COVID-19 related claims, which has two modules, fact-checking and rumour detection. Our fact-checking module, which is supported by novel natural language inference methods with a self-attention network, outperforms state-ofthe-art approaches. It is also able to give automated veracity assessment and ranked supporting evidence with the stance towards the claim to be checked. In addition, PANACEA adapts the bi-directional graph convolutional networks model, which is able to detect rumours based on comment networks of related tweets, instead of relying on the knowledge base. This rumour detection module assists by warning the users in the early stages when a knowledge base may not be available.EACL 2023: The 17th Conference of the European Chapter of the Association for Computational Linguistic
Spatial reticulate polytriphenylamine cathode material with enhanced capacity for rechargeable aluminum ion batteries
Get PDFRechargeable aluminum ion batteries (RAIBs) are a very attractive option for large-scale energy storage thanks to their promising theoretical capacity, high energy density, low cost, abundant earth resources, and environmental friendliness. While the cathode materials chosen and prepared are so essential for the electrochemical performance of RAIBs that extensive efforts and research have been done. In this study, the electrochemical performances of RAIBs were optimally improved by the chemical polymerization of triphenylamine to obtain polytriphenylamine (PTPAn) as the cathode material. The polymerization process improved the spatial reticulate structure of triphenylamine, gained a three-dimensional mesh-like nanostructure, which provided more chemical reaction sites and ion reaction channels, greatly increased the specific surface area, and accelerated the electrochemical reaction kinetics. On this basis, a stable discharge-specific capacity of around 137.4 mAh g−1 was achieved at high current densities of 1 A g−1 for the PTPAn cathode, and the Coulombic efficiency was maintained at about 99% after the life of 500 cycles. The understanding and appreciation of the charging and discharging working principle of PTPAn material as RAIBs cathode, meantime, were deepened by a multitude of ex-situ experiments. These findings are anticipated to serve as the cornerstone for the subsequent development of large-scale RAIBs systems for energy storage that use organic polymers as the cathode material.Ionic
A DNA-barcode biodiversity standard analysis method (DNA-BSAM) reveals a large variance in the effect of a range of biological, chemical and physical soil management interventions at different sites, but location is one of the most important aspects determining the nature of agricultural soil microbiology
Get PDFThere are significant knowledge gaps in our understanding of how to sustainably manage agricultural soils to preserve soil biodiversity. Here we evaluate and quantify the effects of agricultural management and location on soil microbiology using nine field trials that have consistently applied different soil management practices in the United Kingdom using DNA barcode sequence data. We tested the basic hypothesis that various agricultural management interventions have a significant and greater effect on soil bacterial and fungal diversity than geographic location. The analyses of soil microbial DNA sequence data to date has lacked standardisation which prevents meaningful comparisons across sites and studies. Therefore, to analyse these data and crucially compare and quantify the size of any effects on soil bacterial and fungal biodiversity between sites, we developed and employed a post-sequencing DNA-barcode biodiversity standard analysis method (DNA-BSAM). The DNA-BSAM comprises a series of standardised bioinformatic steps for processing sequences but more importantly defines a standardised set of ecological indices and statistical tests. Use of the DNA-BSAM reveals the hypothesis was not strongly supported, and this was primarily because: 1) there was a large variance in the effects of various management interventions at different sites, and 2) that location had an equivalent or greater effect size than most management interventions for most metrics. Some dispersed sites imposed the same organic amendments interventions but showed different responses, and this combined with observations of strong differences in soil microbiomes by location tentatively suggests that any effect of management may be contingent on location. This means it could be unreliable to extrapolate the findings of individual trials to others. The widespread use of a standard approach will allow meaningful cross-comparisons between soil microbiome studies and thus a substantial evidence-base of the effects of land-use on soil microbiology to accumulate and inform soil management decisions.Agriculture and Horticulture Development Board (AHDB); British Beet Research Organisation (BBRO)Soil Biology and Biochemistr
The influence of humic acid on metal(loid)s leaching in landfill leachate for enhancing landfill mining
Get PDFThe aim of this study was to investigate the effect of different concentrations of humic acid on the recovery rate of metal(loid)s in landfill leachate. The study focused on the release of 12 selected metal(loid)s, including critical raw materials (CRM) in landfills that were less than five years old and those that were more than ten years old. The experimental setup involved using different concentrations of humic acid (w/v) (0 %, 0.1 %, and 0.5 %) at pH 4 and 6. The results of the study showed that humic acid was effective in releasing Al, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb. On the other hand, an increase in humic acid concentration led to a decrease in the release of Li, Mn, and Hg. The immobilization of Li, Mn, and Hg was due to the coordination and adsorption of humic acid. The presence of humic acid accelerated the release of metal(loid)s by carboxylic acidity compared to the recovery rate of metal(loid)s in landfill leachate without humic acid. However, a higher concentration of humic acid did not always result in a stronger recovery rate. The recovery rate of metal(loid)s was related to the solubility and concentration of humic acid. These findings can inform the development of more efficient and environmentally-friendly methods of recovering metal(loid)s using humic acid as a leaching agent.Science of the Total Environmen