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Adaption of structured porous media for flow and noise control
No full textThis thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonAerodynamically generated sound is a prevalent issue in engineering, posing significant challenges
for aviation and energy industries. This thesis addresses two self-noise mechanisms relevant
to these sectors: turbulent boundary layer trailing edge noise and the vortex shedding tones
of bluff bodies in crossflow. The literature review underscores the potential of bio-inspired
porous media on aerodynamic and bluff body noise radiations. Although the current approach
is successful due to its mitigation of self-noise emissions, the prevailing application methodology
of porous media is inherently complex. The research efforts on a structured porous material,
which brings many advantages, are light. They not only streamline experimental procedures and
enhance replicability but also open new avenues of contributions due to their ease of modification,
characterisation and optical clarity.
In the first chapter, a Design of Experiments approach was harnessed to fully capture the
effects of the structured porous characteristics on turbulent boundary layer trailing edge noise.
Investigated were streamwise and spanwise separation distances between pores, pore size and
porous coverage. Results show acceptable prediction accuracies are obtained for all the response
variables, proving the approach’s feasibility. A minimum spanwise and streamwise spacing of
pores, in combination with minimum pore diameter and an intermediate level of porous coverage,
presents the optimal configuration to reduce aeroacoustic emission.
The second chapter investigates the application of a simplistic pore arrangement for trailing
edge noise reduction using several 3D-printed trailing edges, each with a single row of pores
parallel to the trailing edge. The approach stimulated a phase-cancellation between the pressure
waves emanating from two sources: the array of pores and the acoustic scattering at the trailing
edge dipole source. The results show that the trailing edges can achieve low-noise radiation, and
a study of the near-wake and boundary layer established that this configuration will not alter
the boundary layer significantly.
Finally, the effects of modifications, based on internal flow field data, to a Structured Porous-
Coated Cylinder on the vortex shedding tones and wake development were investigated. Modifications
of the existing structure were designed to affect the regions of internal flow within the
porous layers to explore how the alteration would impact the vortex shedding attenuating capacity.
The acoustic data confirms the ability of the Structured Porous-Coated Cylinder to reduce
turbulent shedding noise over its bare cylinder counterparts. The modified variants proved the
importance of streamwise communication in the internal structure. Furthermore, the stagnation
regions can be filled, which retains the acoustic performance. Lastly, the removal of the ability
for the flow to travel in the spanwise direction within the internal structure has been shown to
improve the acoustic far-field radiation over the original Structured Porous-Coated Cylinder.EPSR
Performance approaches to whole society resilience
Get PDFData availability statement:
Data is available for this article [from the corresponding author].In this article, we reflect on the ways in which arts practices can contribute productively to national resilience strategies. We focus particularly on the UK Government Resilience Framework (2023, UKGRF) which calls for a ‘whole of society’ approach to resilience, echoing established initiatives addressing ‘whole community’ (USA) and ‘total defence’ (Sweden, Switzerland). In this context, we ask what performance research methods offer to understandings of whole society resilience, and how existing artistic practices ‘perform’ resilience in ways that are currently not accounted for. The arts, we argue, are a nuanced means of attending to complex geo-political contexts that allow space for legacies of racism, sexism, poverty, colonialism, and terrorism to be revealed as having (had) important and differing influences in shaping the resilience of varied communities within society. The UKGRF offers a compelling opportunity to think about what whole of society resilience might involve, who might already be engaged in this work, and how we might develop and maintain a robust ‘whole of society’ approach to contemporary resilience challenges. We discuss Through my Window, a community outreach project run by the Citizens Theatre, Glasgow (UK), mural painting in New Orleans (USA) that offers positive, joyful images of individuals in a city that is too often read through narratives of tourism and crisis, and Remembering a Future (London (UK), 2018), a live performance in which Aman Mojadidi addressed issues of race, identity, home and terrorism. In so doing, we argue that artists, arts organisations and arts communities need to be considered vital, strategically important resilience practitioners, and that the arts should be being taken seriously as an engine of societal resilience more broadly.This work was supported by the Arts and Humanities Research Council [AH/V013734/1]
The Safety Risks of AI-Driven Solutions in Autonomous Road Vehicles
Get PDFData Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article.Appendix A: Table A1. Mapping of Proposed Methods to Automotive Safety Standards ISO 26262 and PAS 8800 Normative Demands is available online at: https://www.mdpi.com/2032-6653/15/10/438#app1-wevj-15-00438 .At present Deep Neural Networks (DNN) have a dominant role in the AI-driven Autonomous driving approaches. This paper focuses on the potential safety risks of deploying DNN classifiers in Advanced Driver Assistance System (ADAS) systems. In our experience, many theoretically sound AI-driven solutions tested and deployed in ADAS have shown serious safety flaws in practice. A brief review of practice and theory of automotive safety standards and related body of knowledge is presented. It is followed by a comparative analysis between DNN classifiers and safety standards developed in the automotive industry. The output of the study provides advice and recommendations for filling the current gaps within the complex and interrelated factors pertaining to the safety of Autonomous Road Vehicles (ARV). This study may assist ARV’s safety, system, and technology providers during the design, development, and implementation life cycle. The contribution of this work is to highlight and link the learning rules enforced by risk factors when DNN classifiers are expected to provide a near real-time safer Vehicle Navigation Solution (VNS).This research received no external funding
Long term safety, continuation rates and subjective and objective success of Posterior Tibial Nerve Stimulation for Overactive Bladder
No full textPhysiological changes in pregnancy can trigger or worsen a variety of pelvic floor symptoms, including stress incontinence, overactive bladder, stress incontinence and prolapse. In order to minimize both physical and psychological morbidity in the short and long term, it is important for clinicians to appropriately stratify individual risk scores and identify and manage pelvic floor disorders during pregnancy. There has been an introduction of perinatal pelvic health services as part of a government review of pelvic health in pregnancy, which aim to prevent pelvic floor dysfunction following pregnancy but identifying women at risk and referring them onwards for support from physiotherapists or specialist nurses and midwives.
This review article aims to discuss the assessment tools, government initiatives and management options for common pelvic floor disorders during pregnancy
Cross Domain Optimization for Speech Enhancement: Parallel or Cascade?
Get PDFWe provide a demo page containing enhanced audio clips from different
models at https://wanliangdaxia.github.io/ .This paper introduces five novel deep-learning architectures for speech enhancement. Existing methods typically use time-domain, time-frequency representations, or a hybrid approach. Recognizing the unique contributions of each domain to feature extraction and model design, this study investigates the integration of waveform and complex spectrogram models through cross-domain fusion to enhance speech feature learning and noise reduction, thereby improving speech quality. We examine both cascading and parallel configurations of waveform and complex spectrogram models to assess their effectiveness in speech enhancement. Additionally, we employ an orthogonal projection-based error decomposition technique and manage the inputs of individual sub-models to analyze factors affecting speech quality. The network is trained by optimizing three specific loss functions applied across all sub-models. Our experiments, using the DNS Challenge (ICASSP 2021) dataset, reveal that the proposed models surpass existing benchmarks in speech enhancement, offering superior speech quality and intelligibility. These results highlight the efficacy of our cross-domain fusion strategy
Learning everyday multitasking activities – An online survey about people’s experiences and opinions
Get PDFData Availability: Available to download from Figshare (https://figshare.com/) under https://doi.org/10.17633/rd.brunel.24211056.v2.Multitasking (MT)–performing more than one task at a time–has become ubiquitous in everyday life. Understanding of how MT is learned could enable optimizing learning regimes for tasks and occupations that necessitate frequent MT. Previous research has distinguished between MT learning regimes in which all tasks are learned in parallel, single-task (ST) learning regimes in which all tasks are learned individually, and mixed learning regimes (Mix) in which MT and ST regimes are mixed. Research using simple laboratory tasks has consistently shown that MT regimes are the most efficient–the so-called dual-task practice advantage. However, it is currently unclear which learning regimes are used in everyday life, and which regime people would prefer if given a choice. To answer these questions, 72 participants completed an online survey to describe their real-life experiences of MT learning (e.g., when learning to drive), their opinions about learning MT activities, and filled out the Multitasking Preference Inventory to assess polychronicity. Descriptive statistics showed that for everyday activities, particularly learning to drive, Mix regimes were both the most used and most preferred method, whereas MT regimes were the least preferred. A potential explanation is that everyday MT tasks are typically complex, and so people prefer to learn the individual tasks first, before combining the tasks into an MT learning regime. Preference to engage in MT, as assessed by the MPI, positively correlated (Pearson’s r = .24) with preference for MT learning regimes, suggesting that individual differences in learning of complex everyday MT activities can be determined. In conclusion, everyday life multitasking activities such as learning to drive are mostly learned in Mix regimes, i.e. a combination of ST and MT training, and people’s preference to learn such activities with MT regimes increases with their level of polychronicity.This study is part of a self-funded PhD and did not receive any external funding
The power of oversight: institutional investors as moderators of the earnings quality-information asymmetry nexus in Europe
Get PDFThe authors are grateful for comments of the EAA Annual Congress and the BAFA Annual Conference.Purpose:
While there is some evidence of a relationship between earnings quality and information asymmetry, there is limited evidence on the moderating role of institutional investors in this relationship. To fill this gap, this study aims to examine how institutional ownership affects the relationship between earnings quality and information asymmetry, with a focus on the impact of different investment horizons.
Design/methodology/approach:
This study uses a sample of listed European firms from 2000 to 2022. Earnings quality is measured using the McNichols (2002) modification of the Dechow and Dichev (2002) model. The analysis examines the moderating effect of institutional ownership on the relationship between earnings quality and information asymmetry.
Findings:
This study finds that the relationship between earnings quality and information asymmetry is more pronounced in firms with a higher percentage of institutional ownership. This study finds that the monitoring role of long-term institutional investors is more effective than that of short-term institutional investors. This study also finds that the influence of institutional investors is more significant in firms with incentives to engage in earnings management.
Practical implications:
The findings provide evidence suggesting that institutional investors are an important class of investors in terms of exercising an effective monitoring role to mitigate information asymmetry and demand higher earnings quality from their investee firms. These findings are informative for many financial reporting participants, including investors, analysts, regulators and managers.
Originality/value:
This study extends the existing research examining the relationship between earnings quality and information asymmetry (e.g. Affleck-Graves et al., 2002; Ascioglu et al., 2012; Bhattacharya et al., 2013; Jayaraman, 2008; Liu and Elayan, 2015) by examining the moderating effect of institutional ownership on this relationship. It further contributes to the literature by distinguishing between long- and short-term institutional investors and their respective monitoring roles. In addition, this study broadens the geographical scope of the research by using cross-country data from European firms, providing evidence that country-specific factors do not uniformly affect the relationship between earnings quality and information asymmetry
Thirty-five years of feminism and family law in the legal academy
Get PDFThis chapter is in two parts, each of which reflects upon the developments and current state of family law scholarship and feminist teaching in universities in England and Wales. Piper focuses on the enormous body of research and writing that Felicity Kaganas achieved in over 35 years of research in family law. It outlines the publications that she and Kaganas wrote together and highlights Kaganas’ other significant work. It reflects upon the impact of this work for students, academic colleagues and policy-makers and concludes that many of the same issues Kaganas addressed over the years remain current. Auchmuty, on the other hand, reflects upon 35 years of feminism in the classroom. Both Auchmuty and Kaganas started teaching in English law schools in the 1980s when the job was very different. Since that time, law teaching has become an increasingly feminised profession, with feminist teachers occupying some of the highest positions, and feminist legal research has flourished. In spite of these two profound shifts, the law degree has remained virtually unchanged, especially in respect of the ‘core curriculum’. These reflections consider why this is so, focusing on mechanisms of patriarchal containment and backlash, and considers what can be done about it
You’ve been framed! Charlie Hebdo and WikiLeaks – The Geoculture of Free Speech
Get PDFThis article examines the issue of free speech as a part of what world-systems scholars call the geoculture of the modern world-system. It does so by comparing and contrasting responses from governing political and media institutions in the UK and the US to Julian Assange’s Wikileaks revelations and the Charlie Hebdo murders. The purpose of this comparison is to show that the commitment to free speech on the part of these media and governing institutions is instrumental rather than principled since powerful vested interests are involved. The West’s claim to be the defender of liberal values is contingent upon geo-political and economic circumstance. In short, power and interest tend to transcend liberal, universal principles in practice for reasons that the two cases demonstrate. The framing device of worthy versus unworthy victims (as set out by Herman and Chomsky in their book Manufacturing Consent) helps to explain responses to the Hebdo killings and the treatment of Julian Assange/Wikileaks by UK and US governing institutions
Search for supersymmetry in final states with disappearing tracks in proton-proton collisions at = 13 TeV
No full textA preprint version of this article is available at arXiv:2309.16823v2 [hep-ex], https://arxiv.org/abs/2309.16823v2 . Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/SUS-21-006 (CMS Public Pages). Report number: CMS-SUS-21-006, CERN-EP-2023-209.A search is presented for charged, long-lived supersymmetric particles in final states with one or more disappearing tracks. The search is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC between 2016 and 2018, corresponding to an integrated luminosity of Formula Presented. The search is performed over final states characterized by varying numbers of jets, Formula Presented-tagged jets, electrons, and muons. The length of signal-candidate tracks in the plane perpendicular to the beam axis is used to characterize the lifetimes of wino- and Higgsino-like charginos produced in the context of the minimal supersymmetric standard model. The Formula Presented energy loss of signal-candidate tracks is used to increase the sensitivity to charginos with a large mass and thus a small Lorentz boost. The observed results are found to be statistically consistent with the background-only hypothesis. Limits on the pair-production cross section of gluinos and squarks are presented in the framework of simplified models of supersymmetric particle production and decay, and for electroweakino production based on models of wino and Higgsino dark matter. The limits presented are the most stringent to date for scenarios with light third-generation squarks and a wino- or Higgsino-like dark matter candidate capable of explaining the observed dark matter relic density.SCOAP3
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