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Thermocouple selection and its influence on temperature monitoring of lithium-ion cells
Get PDFAccurate battery modelling requires precise measurements of key battery characteristics, including their surface temperature during fast charging and discharging states. Battery surface temperature measurements are also used to mitigate thermal events such as thermal runaway, which can cause fires. Established literature has shown that there are significant variations in temperature measurements of the surface of lithium-ion cells between various thermocouple sensors, including common K and T-Type thermocouples. In this paper, these variations in temperature measurements are investigated for the first time in the context of battery characterisation. The surface temperatures of two lithium-ion cells, a 21700-model Lithium Nickel Cobalt Aluminium Oxide (NCA) cylindrical cell and a Lithium Titanate Oxide (LTO) pouch cell, are measured during high current cycling using a variety of different thermocouples and an infrared camera to study the variations and response times in the temperature measurements recorded. The impact of electromagnetic fields emitted by the lithium-ion cells on the temperature measurements is also investigated. Results reported indicate a trend in the size of the temperature sensor with the response time of the cell surface temperature measurements. The recommendations of temperature sensors based on these findings allow for improved response time and accuracy of cell surface temperature measurements
Probabilistic assessment of 3D slope failures in spatially variable soils by cooperative stochastic material point method
Get PDFAccurate assessment of slope failures and their large deformations is critical for effective landslide mitigation. This study introduces the new Cooperative Stochastic Material Point Method (CSMPM), addressing challenges in probabilistic characterization of slope large deformations considering three-dimensional (3D) soil heterogeneities. The method employs an enhanced Karhunen-Loève (KL) expansion to model 3D soil spatial variability efficiently. By using rough and refined grids, derived through the enhanced KL expansion, the study achieves computational efficiency without compromising accuracy. By combining the computational advantages of the rough grid with the precision of the refined grid, the CSMPM enables efficient probabilistic analysis of 3D heterogeneous slopes. The results demonstrate its capability to identify slope large deformation failure modes and quantify the associated failure probability. Notably, the shallow failure mode exhibits fan-shaped horizontal diffusion, introducing uncertainty, while the compound failure mode presents challenges in landslide prevention. The progressive failure mode poses the highest hazard. Horizontal heterogeneities significantly influence both large deformation likelihood and failure modes, emphasizing the importance of 3D soil spatial variability in geotechnical reliability assessments. The CSMPM, with its innovative approach, proves to be a practical tool for enhancing our understanding of geohazards and associated uncertainties, as well as large deformations. It provides valuable insights for improving risk assessment of slope hazards
Routing schemes for hybrid communication networks
Get PDFWe consider the problem of computing routing schemes in the HYBRID model of distributed computing where nodes have access to two fundamentally different communication modes. In this problem nodes have to compute small labels and routing tables that allow for efficient routing of messages in the local network, which typically offers the majority of the throughput. Recent work has shown that using the HYBRID model admits a significant speed-up compared to what would be possible if either communication mode were used in isolation. Nonetheless, if general graphs are used as the input graph the computation of routing schemes still takes polynomial rounds in the HYBRID model. We bypass this lower bound by restricting the local graph to unit-disc-graphs and solve the problem deterministically with running time O(|H|2+logn), label size O(logn), and size of routing tables O(|H|2⋅logn) where |H| is the number of “radio holes” in the network. Our work builds on recent work by Coy et al., who obtain this result in the much simpler setting where the input graph has no radio holes. We develop new techniques to achieve this, including a decomposition of the local graph into path-convex regions, where each region contains a shortest path for any pair of nodes in it
Reforming primary palliative care : a call to arms
No full textGPs and other professionals in primary care provide the majority of palliative and end-of-life care (PEoLC) in the community. Policy and quality improvement guidance for such healthcare professionals must reflect an understanding of the context. Considerable work has been done internationally to advocate for integrated primary palliative care. For example, output from the World Health Organization following the Global Conference on Primary Health Care specifically highlights palliative care as a key aspect of primary care.1
The voices of primary care professionals are vital to the future development of health care to meet the increasing PEoLC needs of the population. As members of the Society for Academic Primary Care Palliative Care Special Interest Group (SAPC PC SIG), we intend to get them heard. This editorial highlights the essential role of general practice in palliative care provision, and the benefits to patients, clinicians, and policymakers in embracing and nurturing this aspect of care. Box 1 provides definitions of terms used throughout this article
Public procurement and labour market inequality : conceptualising a multi-faceted relationship
Get PDFOver the past few decades, policymakers have become increasingly intrigued by public procurement's potential to serve as a policy tool. In line with an increased prevalence of attempts to leverage public procurement for promoting employment-related goals, a growing body of research explores the linkages between public procurement and employment. Yet, while different aspects of the procurement process influence labour market outcomes and the linkages are multiple, current research focuses on individual aspects only. As a result, current understandings of the linkage between public procurement and its labour market effects remain fragmented. Considering choices between the initial identification of an object of purchase and the award and delivery of the contract, this article conceptualises the multi-faceted linkages between public procurement and labour market inequalities understood as issues ofaccess to and (in)equality in employment. It argues that three key aspects (the design of the object, requirements set in the process of buying, and the type of provider) make distinct contributions to the overall impact that procurement processes have on labour market inequality and outlines a framework for analysing the implications of choices at these three core decision points
Re-use of samples in stochastic annealing
No full textThe re-use of samples in stochastic black box optimisation is a double-edged sword. On the one hand it has the potential of substantially reducing the number of simulation runs required, on the other hand it introduces dependencies between iterations of the optimisation algorithm that may misguide the search. This paper proposes a principled way to re-use samples in stochastic annealing, a generalisation of simulated annealing for stochastic black-box optimisation problems. We propose three alternative algorithms that all, despite the stochastic errors when evaluating a solution via simulation, obey the detailed balance equation and thus have the same assurance of converging to the true optimum as standard simulated annealing in the deterministic case. This is achieved by optimising in the product space of solution and error. We compare our new algorithms in terms of their acceptance ratio as well as empirically on two stochastic combinatorial optimisation problems and find that the best algorithms are of order twice as efficient as the state-of-the-art. Furthermore, one algorithm we propose can work with non-Gaussian and even unknown error distributions
An enhanced block validation framework with efficient consensus for secure consortium blockchains
Get PDFConsortium blockchains have attracted considerable interest from academia and industry due to their low-cost installation and maintenance. However, typical consortium blockchains can be easily attacked by colluding block validators because of the limited number of miners in the systems. To address this problem, in this paper, we propose a novel block validation framework to enhance blockchain security. In the framework, the block validations are assisted and implemented by various lightweight nodes, e.g., edge devices, in addition to the typical blockchain miners. This improves the blockchain security but can cause an increased block validation delay and, thereby, reduced blockchain throughput. To tackle this challenge, we propose an effective method to select lightweight nodes based on their computing powers to maximize the blockchain throughput, and prove the uniqueness of the optimal nodes selection strategy. Security analysis and simulation results from the deployed consortium blockchain platform show that the proposed framework achieves higher throughput and security than the existing consortium blockchain models
Early age hydration behaviour of foam concrete containing a coal mining waste : novel experimental procedures and effects of capillary pressure
Get PDFGlobally, coal mining wastes (CMWs) are associated with significant environmental and economic costs. Processing CMW into an ingredient of foam concrete is a promising solution but the behaviour of this particular construction material has not been sufficiently evaluated, especially during the initial period of cement hydration. The purpose of this paper is to present novel laboratory set-up and experimental procedures designed to investigate the early age behaviour of hydrating foam concrete samples made with a CMW from Poland. Two types of tests were devised to simulate air-curing conditions and water-curing conditions, respectively. These tests were carried out in custom-built unsaturated oedometer cells, and the matric suction in the test samples was monitored for approximately 14 days, using Warwick high capacity tensiometers. Experimental results show that in both curing conditions, a higher matric suction during cement hydration corresponds to a denser sample at the end of the monitoring period. A comparison of water-cured and air-cured samples also reveals different responses to CMW inclusion in their mix designs. The responses can be convincingly explained based on complementary test data and idealised capillary tube models adapted for the hydrating foam concrete samples
DIC study of strain concentrations and damage within web-flange junctions of pultruded GFRP bridge decking
Get PDFThis paper reports an experimental study into damage progression within the web-flange junctions of locally-loaded pultruded glass-fibre reinforced-polymer bridge decking, owing to amplified normal and shear stresses at misaligned fibre-resin interfaces. To that end 3D digital image correlation (DIC) is used in three roles, namely quantifying high strains along misaligned fibre layers, detecting onset of damage and identifying macroscopic damage via patterns in the unfiltered strain fields. Both DIC and strain gauges alongside analytical strain predictions are used to increase confidence in the test data. The DIC data reveal that the strains along the misaligned fibre-resin interfaces were shear dominated, and that a 0.8 mm increase of wrinkle-amplitude led to a 92 % increase in peak shear strain. Micro-cracking was detected at approximately 50 % of the test load that caused the first delamination. In repeat tests this load dropped by 27 % due to random transverse cracks within the roving core
Dust and death : evidence from the West African harmattan
No full textUsing two decades of data from 12 low-income countries in West Africa, we show that dust carried by harmattan trade winds increases infant and child mortality. Health investments respond to dust exposure, consistent with compensating behaviors. Despite these efforts, surviving children still exhibit negative health impacts. Our data allow us to investigate differential impacts over time and across countries. We find declining impacts over time, indicating adaptation. Using national-level measures of macroeconomic conditions and health resources, we find suggestive evidence that both economic development and public health improvements have contributed to this adaptation, with health improvements playing a larger role