19684 research outputs found
Sort by
Anisotropic plastic deformation and damage evolution of sapphire under nanoindentation
No full textSapphire has extensive applications in advanced manufacturing fields, including electronics and semiconductors. However, its pronounced anisotropy poses significant challenges for ultra-precision machining and effective damage control. This study systematically investigates the anisotropic mechanisms of plastic deformation and subsurface damage (SSD) evolution across different sapphire crystal planes. This is achieved using molecular dynamics simulations, nanoindentation experiments, and transmission electron microscopy characterization. The results definitively show that distinct slip system behaviors depend on crystal orientation: the basal plane acts as the primary slip plane for the A/M/R-planes, whereas the rhombohedral slip is dominant for the C-plane. Subsurface damage of the A/M-planes is dominated by the formation of dislocation loops, whereas the C/R-planes primarily exhibit cross-slips. It was also identified that crack initiation and propagation mechanisms are closely linked to twinning behaviors. Cracks preferentially nucleate and propagate along the twinning planes, with basal and rhombohedral twinning playing key roles. The formation and evolution of SSD are significantly influenced by the activation and interaction of slip systems, leading to variations in damage depth, with a clear trend of M-plane > A-plane > R-plane. On the C-plane, basal slip initially minimizes damage; however, increased indentation depth activates rhombohedral slip, exacerbating SSD. Furthermore, a theoretical slip system activation model was successfully developed and validated, accurately predicting SSD evolution. These findings provide a robust theoretical basis for optimizing low-damage ultra-precision machining processes for sapphire and other anisotropic crystalline materials.</p
Hybrid Piezoelectric-Electromagnetic Cut-Out Energy Harvester with Adaptive Potential Wells:Design and Nonlinear Modeling
No full textPurpose: This paper presents a novel bistable, multi-frequency hybrid energy harvesting mechanism with an adaptive potential barrier, aimed at improving energy scavenging efficiency in low-excitation environments. Methods: The system employs a recently developed bistable two-degree-of-freedom cut-out piezoelectric harvester, which achieves substantial power output through two closely positioned resonances. However, conventional bistable harvesters underperform when the excitation level is insufficient to overcome the potential barrier. To address this, an auxiliary magnetic oscillator is incorporated into the original cut-out harvester to lower the barrier dynamically and facilitate inter-well oscillations. Also, an induction coil surrounding the magnetic oscillator scavenges extra electrical power, further enhancing the overall power generation. The mathematical model is derived through a hybrid procedure combining the Ritz method with the Euler-Bernoulli beam and magnetic dipole theories. The model accuracy is validated by the available experimental observations for simpler systems. Furthermore, a bistability criterion is introduced, outlining the system properties required to trigger inter-well oscillations. Results: Numerical results demonstrate that the proposed harvester overcomes the potential barrier at lower excitation amplitudes and achieves higher generated power over a broader frequency bandwidth. Under a 4.5 m/s² excitation, the hybrid harvester generates a maximum average power of approximately 12 mW, representing a 118% improvement over the conventional design. Conclusion: The analyses confirm that the proposed hybrid design significantly improves energy harvesting efficiency compared to conventional designs reported in the literature.</p
The MACB Problem:Definitions, Variants, and a PDDL+ Approach
No full textModular Autonomous Customised Bus Systems (MACB) promise to significantly enhance public transport attractiveness and accessibility, leading to improved quality of life and reduced emissions. Compared to traditional bus systems, MACB provides a problem that poses a new set of challenges, ranging from the allocation of vehicles to the optimisation of routes and recharges. The MACB problem is attracting increasing interest within the transport research community, but it presents characteristics and dimensions that lend themselves well to approaches based on planning and combinatorial search. In this paper, with the aim of bridging the gap between different research communities, we provide a crisp definition of the MACB problem and present a planning-based approach to solve a specific variant of the problem, together with a set of benchmarks to foster research on this topic.<br/
The effects of ensemble singing on heaviness in metal music:Revisiting a systematic approach
No full textThis article explores how ensemble vocals contribute to the perception of heaviness in metal music. It argues that heaviness is not solely an instrumental attribute but may also be influenced by vocal techniques, arrangement, and production. Drawing from Herbst and Mynett’s research on heaviness, the article analyses how that framework applies to ensemble vocals. It distinguishes between absolute aspects (e.g., distortion and frequency spectrum) and relational aspects (e.g., vocal clarity, psychoacoustic space, and symbolic extremity) of heaviness. Case studies reveal the limitations of a purely instrumental lens on heaviness. The article further proposes that the relationships between elements in the composition and production of a track are significant aspects to consider when discussing heaviness, highlighting how it can be shaped by the interplay of physical and relational aspects, encompassing compositional choices and cultural expectations
Evaluation of clinical performance of additively manufactured and milled polyetheretherketone (PEEK) inlays compared with indirect composite resin inlays over a one-year follow-up:A randomized clinical trial
No full textStatement of problem: Data on polymer materials, particularly polyetheretherketone (PEEK) used in restorative dentistry, are scarce, as is knowledge concerning the clinical efficacy of PEEK restorations produced through additive manufacturing when compared with existing indirect materials and techniques. Purpose: The purpose of this randomized clinical trial was to evaluate the clinical performance of additively manufactured and milled PEEK inlays compared with composite resin inlays according to modified United State Public Health Service (USPHS) criteria over a 1-year follow- up. Material and methods: Participants were allocated into 3 distinct categories based on the materials and techniques used: R1 denoting teeth restored with 3 dimensionally (3D) printed PEEK inlays (N=16), R2 representing teeth restored with milled PEEK inlays (N=16), and R3 indicating the comparator group comprising teeth restored with milled composite resin inlays (N=16). After the placement of inlay restorations, evaluations were conducted at 3 time points (T): baseline (T0), 6 months (T1), and 12 months (T2) by using the modified USPHS criteria for assessing anatomic form, color match, marginal discoloration, marginal adaptation, surface texture, secondary caries, retention, and postoperative sensitivity. Ordinal data were analyzed using the Kruskal-Wallis test, followed by the Dunn post hoc test for between group comparisons, as well as the Friedman test, followed by the Nemenyi post hoc test for within group comparisons (α=.05). Results: Across all parameters and intervals, most of the restorations within each group exhibited an alfa score, with no statistically significant differences noted (P>.05). However, concerning color match, all restorations within the PEEK groups received a bravo score, indicating a statistically significant difference in intergroup comparison between the milled composite resin groups and the PEEK group (P<.001). However, no significant variances were noted in the scores evaluated across different follow-up periods (P>.05). Conclusions: Subtractive and additive manufacturing techniques, as well as PEEK and composite resin materials together, offer clinically acceptable functioning restorations over 1 year. PEEK material can be used as a suitable alternative to commonly used indirect composite resin intracoronal restorations in posterior areas. Improvements in terms of surface texture and esthetics are required.</p
Modular system of additive manufacturing benchmarking artefacts for XCT inspection using a design-for-metrology approach
No full textAdditive Manufacturing (AM) offers freedom in both design and materials selection. Safety critical industries, such as aerospace and healthcare, stand to benefit from the unique capabilities offered by AM. However, adoption of AM is hindered by the unique and complex inspection and quality assurance requirements that conventional line-of-sight techniques struggle to fulfil. X-ray computed tomography (XCT) is a non-destructive, non-line-of-sight, volumetric imaging technique, which has gained traction as a viable inspection method over the last two decades and shows promise as a next generation dimensional metrology tool for AM. This paper details the development of a system of modular artefacts which provide a reconfigurable toolkit to address a variety of AM metrology challenges. The toolkit consists of AM test, and XCT data validation modules. The test modules are engineered to assess the ability of an AM system to produce challenging geometries. Additionally, several XCT data validation modules are introduced, which are intended to reduce measurement uncertainty by providing a consistent repeatably measured ground truth in the form of features of known size and shape in each dataset. The AM test modules are parameterised based on AM process and XCT scanning parameters, enabling the modules to be adapted for specific requirements
SC-FPP:breaking 1 kHz frame-rate limits of 3D reconstruction with industrial cameras via snapshot compressive fringe projection profilometry
No full textFringe projection profilometry (FPP) is constrained by the synchronization mechanism of projector-camera pairs, limiting its application in high-spatiotemporal-resolution scenarios, such as additive manufacturing molten pool monitoring and dynamic testing. Specifically, the 3D reconstruction frame rate of FPP is limited by the camera transmission bandwidth and the length of projection sequence required for unambiguous phase retrieval: an f Hz industrial camera typically achieves up to only f/P Hz 3D imaging (P is the projection sequence length). This frame-rate loss restricts industrial monitoring to ∼100 Hz. To address the problem, we propose the snapshot compressive FPP (SC-FPP), a high-speed 3D imaging method that integrates FPP with snapshot compressive imaging (SCI). By employing random spatial optical field encoding and subsequent fringe images recovery, SC-FPP enables high-resolution 3D imaging at up to Bf/P Hz (B is the compression ratio). Hybrid simulation experiment results show that SC-FPP enables 3D imaging at over 1 kHz using an industrial camera by setting B=P. At the same time, accuracy validation further demonstrates that SC-FPP delivers superior measurement precision, reaching an RMSE of 36.6 μm in standard sphere tests. This method breaks through the hardware frame-rate limit of industrial cameras, providing a low-cost, high-performance solution for in-process high-speed 3D monitoring.</p
A scoping review of materials and approaches for developing antibacterial textiles
No full textAntimicrobial textiles are specialised fibres and fabrics designed to either annihilate or significantly reduce the growth of harmful microbes like bacteria, viruses, and fungi. Nowadays, antibacterial textiles are extensively used in healthcare, athletic wear, home textiles, hospitality, protective clothing and so on. This comprehensive review covers the relevant literature published in this area during the last two decades (2003-2024). The various mechanisms of antibacterial activity have been presented, followed by different inorganic, organic and natural agents used for this purpose. The techniques like chemical grafting, in-situ deposition, melt spinning routes and plasma treatment have been succinctly covered. Use of antibacterial agents for controlled drug delivery has been elucidated. Finally, the application areas and the potential ecological and health risks of using antibacterial agents have been highlighted. Several research works have described the release of these antibacterial agents into the soil that deteriorates the health of the soil bydestroying or impeding the activity of beneficial soil microorganisms. In conclusion, future research directions have been presented. This review will act as a compendium of recent research in the domain of antibacterial textiles
Impact of Australian home medicines reviews on continuous polypharmacy and associated costs among older women:a cohort study
No full textIntroduction: Medication misadventure is associated with the use of polypharmacy and is highly prevalent in the older population living in the community, especially among women. Aim: This study aimed to determine the impact of Home Medicines Reviews (HMRs) on continuous polypharmacy, the prevalence of continuous polypharmacy, and inflation-adjusted differences in costs among women who did and did not receive HMRs. Method: The study included 9347 participants from the Australian Longitudinal Study on Women’s Health who fulfilled the eligibility criteria from 77–82 years in 2003 to 91–96 years in 2017. Generalised estimating equations were used to estimate the association between HMRs and continuous polypharmacy. Out-of-pocket costs and benefits paid to government were presented as median costs for each participant from 2003 to 2017, alongside interquartile ranges. Results: Only a small percentage of women received HMRs in 2003 (1.14%) but this percentage increased over time to 2017 (3.95%). The prevalence of continuous polypharmacy in 2017 was 39.06% amongst women who received an HMR and 28.05% amongst women who did not receive an HMR. There was evidence for an association between the use of HMRs and continuous polypharmacy in the following calendar year (OR 1.12; 95% CI 1.03, 1.21). There was an increase in out-of-pocket (OOP) medication costs in both women with and without HMRs, with the HMR group demonstrating higher OOP medication costs (AUD57) than the non-HMR group (AUD50). Conclusion: HMRs were associated with a modest increase in the odds of continuous polypharmacy in the subsequent year. Increase in OOP medication costs over time highlights the need to further optimise cost-effective medications for individuals.</p
Business group affiliation and misreporting:evidence from Korean chaebols
No full textWhile prior studies suggest that business groups actively manage their earnings, direct evidence on whether or how they ultimately violate accounting rules remains scarce. Our investigation of Korean business groups reveals a negative association between business group affiliation and detected misreporting propensity, unexpectedly signalling less detection of misreporting among group affiliates. However, further analyses indicate that misreporting complexity, captured by cases involving valuation of derivatives, private companies, and other complex financial instruments, may obscure detection of misreporting in business groups. We also find that within business groups, misreporting is disproportionately concentrated in affiliates positioned closer to controlling families on the pyramidal ownership chain, where it is more likely to benefit these controlling families. However, misreporting affiliates are rarely the ultimate parents. Overall, our findings suggest that business groups strategically balance the costs and benefits of misreporting to maximise gains for controlling owners while mitigating their exposure to legal and reputational risks
Access Repository Dashboard
Do you manage Huddersfield Research Portal? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!