37,253 research outputs found

    Application of Multichannel Active Vibration Control in a Multistage Gear Transmission System

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    Gears are the most important parts of rotating machinery and power transmission devices. When gears are engaged in meshing transmission, vibration will occur due to factors such as gear machining errors, meshing rigidity, and meshing impact. The traditional FxLMS algorithm, as a common active vibration algorithm, has been widely studied and applied in gear transmission system active vibration control in recent years. However, it is difficult to achieve good performance in convergence speed and convergence precision at the same time. This paper proposes a variable-step-size multichannel FxLMS algorithm based on the sampling function, which accelerates the convergence speed in the initial stage of iteration, improves the convergence accuracy in the steady-state adaptive stage, and makes the modified algorithm more robust. Simulations verify the effectiveness of the algorithm. An experimental platform for active vibration control of the secondary gear transmission system is built. A piezoelectric actuator is installed on an additional gear shaft to form an active structure and equipped with a signal acquisition system and a control system; the proposed variable-step-size multichannel FxLMS algorithm is experimentally verified. The experimental results show that the proposed multichannel variable-step-size FxLMS algorithm has more accurate convergence accuracy than the traditional FxLMS algorithm, and the convergence accuracy can be increased up to 123%

    Metaphors of London fog, smoke and mist in Victorian and Edwardian Art and Literature

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    Julian Wolfreys has argued that after 1850 writers employed stock images of the city without allowing them to transform their texts. This thesis argues, on the contrary, that metaphorical uses of London fog were complex and subtle during the Victorian and Edwardian periods, at least until 1914. Fog represented, in particular, formlessness and the dissolution of boundaries. Examining the idea of fog in literature, verse, newspaper accounts and journal articles, as well as in the visual arts, as part of a common discourse about London and the state of its inhabitants, this thesis charts how the metaphorical appropriation of this idea changed over time. Four of Dickens's novels are used to track his use of fog as part of a discourse of the natural and unnatural in individual and society, identifying it with London in progressively more negative terms. Visual representations of fog by Constable, Turner, Whistler, Monet, Markino, O'Connor, Roberts and Wyllie and Coburn showed an increasing readiness to engage with this discourse. Social tensions in the city in the 1880s were articulated in art as well as in fiction. Authors like Hay and Barr showed the destruction of London by its fog because of its inhabitants' supposed degeneracy. As the social threat receded, apocalyptic scenarios gave way to a more optimistic view in the work of Owen and others. Henry James used fog as a metaphorical representation of the boundaries of gendered behaviour in public, and the problems faced by women who crossed them. The dissertation also examines fog and individual transgression, in novels and short stories by Lowndes, Stevenson, Conan Doyle and Joseph Conrad. After 1914, fog was no more than a crude signifier of Victorian London in literature, film and, later, television, deployed as a cliche instead of the subtle metaphorical idea discussed in this thesis

    Building body identities - exploring the world of female bodybuilders

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    This thesis explores how female bodybuilders seek to develop and maintain a viable sense of self despite being stigmatized by the gendered foundations of what Erving Goffman (1983) refers to as the 'interaction order'; the unavoidable presentational context in which identities are forged during the course of social life. Placed in the context of an overview of the historical treatment of women's bodies, and a concern with the development of bodybuilding as a specific form of body modification, the research draws upon a unique two year ethnographic study based in the South of England, complemented by interviews with twenty-six female bodybuilders, all of whom live in the U.K. By mapping these extraordinary women's lives, the research illuminates the pivotal spaces and essential lived experiences that make up the female bodybuilder. Whilst the women appear to be embarking on an 'empowering' radical body project for themselves, the consequences of their activity remains culturally ambivalent. This research exposes the 'Janus-faced' nature of female bodybuilding, exploring the ways in which the women negotiate, accommodate and resist pressures to engage in more orthodox and feminine activities and appearances

    The Professional Identity of Doctors who Provide Abortions: A Sociological Investigation

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    Abortion is a medicalised problem in England and Wales, where the law places doctors at the centre of legal provision and puts doctors in control of who has an abortion. However, the sex-selection abortion scandal of 2012 presented a very real threat to 'abortion doctors', when the medical profession's values and practices were questioned in the media, society and by Members of Parliament. Doctors found themselves at the centre of a series of claims that stated doctors were acting both illegally and unethically, driven by profit rather than patient needs. Yet, the perspectives of those doctors who provide abortions has been under-researched; this thesis aims to fill that gap by examining the beliefs and values of this group of doctors. Early chapters highlight the ambiguous position of the abortion provider in Britain, where doctors are seen as a collective group of professionals motivated by medical dominance and medical autonomy. They outline how this position is then questioned and contested, with doctors being presented as unethical. By studying abortion at the macro-, meso- and micro-levels, this thesis seeks to better understand the values of the 'abortion doctor', and how these levels shape the work and experiences of abortion providers in England and Wales. This thesis thus addresses the question: 'What do abortion doctors' accounts of their professional work suggest about the contemporary dynamics of the medicalisation of abortion in Britain?'. It investigates the research question using a qualitative methodological approach: face-to-face and telephone interviews were conducted with 47 doctors who provide abortions in England and Wales. The findings from this empirical study show how doctors' values are linked to how they view the 'normalisation of abortion'. At the macro-level doctors, openly resisted the medicalisation of abortion through the position ascribed to them by the legal framework, yet at the meso-level doctors construct an identity where normalising abortion is based on further medicalising services. Finally, at the micro-level, the ambiguous position of the abortion provider is further identified in terms of being both a proud provider and a stigmatised individual. This thesis shows that while the existing medicalisation literature has some utility, it has limited explanatory power when investigating the problem of abortion. The thesis thus provides some innovative insights into the relevance and value of medicalisation through a comprehensive study on doctors' values, beliefs and practices

    Biocontrol as a key component to manage brown rot on cherry

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    Brown rot, caused by Monilinia spp., is one of the most important diseases in stone fruits worldwide. Brown rot can cause blossom wilts and fruit rots in the orchard as well as latent infections of fruit, leading to post-harvest fruit decaying. Current control methods rely on scheduled spraying of fungicides. However, the continuing pressure to reduce fungicide use has seen an increase in research into alternative management methods, such as biological control. NIAB EMR recently identified two microbes that significantly reduced sporulation of Monilinia laxa under laboratory conditions. These two isolates were a bacterial species Bacillus subtilis (B91) and yeast-like fungus Aureobasidium pullulans (Y126) and are currently being formulated into commercial products. We are investigating how to optimise the use of these two potential biocontrol products in practice, in terms of suppressing Monilinia sporulation on overwintered mummies and preventing infection of blossoms and fruits. When applied to mummified fruits in winter Y126’s population was stable through the winter but at a low concentration. The B91 survived a little longer with the population reaching that of the control group by week 4. Neither Biological control (BCA) treatments had an affected the population of M. laxa when compared to the control treatment of sterile distilled water. The interaction time between the BCAs and M. laxa showed the longer the interaction time the lower the spore count of M. laxa. Another study was performed looking into the ability of our BCAs to colonise and survive on blossoms. B91 did not survive well on blossoms but could survive on fruits. However, its antagonistic compounds need to be in relatively high concentration to be effective against M. laxa. Therefore, it is best used as a fungicide, ensuring the antagonistic compounds are at a high concentration when applied in the field. Y126 can persist throughout the season and was marginally, though not statistically significantly, more effective at long term reduction in M. laxa. This could be because Y126 works through competition, therefore the interaction time with the pathogen could be important for efficacy and something worth investigating further. The difference between the BCAs highlights the need to understand each BCA’s ecology to ensure maximum efficacy. In a latent infection experiment, we inoculated trees with M. laxa and then treated them with the two biocontrol isolates two weeks before harvest. Post-harvest disease development was assessed after four days of storage in 2019 and two weeks in 2020. There was a significant reduction in rot incidence (p < 0.001) of 29% (Y126) and 27% (B91) in 2019 and 62 % (Y126) and 80 % (B91) in 2020 when the harvested fruit was stored at cold store levels. With new products to be introduced into the environment, it's important to understand the effects they may have on the plant's microbiome. Using next-generation sequencing techniques, we looked at the impact B91 and Y126 has on the blossom and cherry microbiomes. There was a treatment effect in both the bacterial and fungal communities on the blossom and ripe cherry. But the biggest variability was between blocks (Geographical effect) and between the years in which we experimented (p < 0.0001). This research will assist in the development of management strategies, especially spray timings for brown rot on stone fruit, integrating BCAs with other management practices

    Carbon dioxide removal potential from decentralised bioenergy with carbon capture and storage (BECCS) and the relevance of operational choices

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    Bioenergy with carbon capture and storage (BECCS) technology is expected to support net-zero targets by supplying low carbon energy while providing carbon dioxide removal (CDR). BECCS is estimated to deliver 20 to 70 MtCO2 annual negative emissions by 2050 in the UK, despite there are currently no BECCS operating facility. This research is modelling and demonstrating the flexibility, scalability and attainable immediate application of BECCS. The CDR potential for two out of three BECCS pathways considered by the Intergovernmental Panel on Climate Change (IPCC) scenarios were quantified (i) modular-scale CHP process with post-combustion CCS utilising wheat straw and (ii) hydrogen production in a small-scale gasifier with pre-combustion CCS utilising locally sourced waste wood. Process modelling and lifecycle assessment were used, including a whole supply chain analysis. The investigated BECCS pathways could annually remove between −0.8 and −1.4 tCO2e tbiomass−1 depending on operational decisions. Using all the available wheat straw and waste wood in the UK, a joint CDR capacity for both systems could reach about 23% of the UK's CDR minimum target set for BECCS. Policy frameworks prioritising carbon efficiencies can shape those operational decisions and strongly impact on the overall energy and CDR performance of a BECCS system, but not necessarily maximising the trade-offs between biomass use, energy performance and CDR. A combination of different BECCS pathways will be necessary to reach net-zero targets. Decentralised BECCS deployment could support flexible approaches allowing to maximise positive system trade-offs, enable regional biomass utilisation and provide local energy supply to remote areas

    Sexual violence as a form of social control : the role of hostile and benevolent sexism

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    This thesis examines the feminist hypothesis that rape functions as a tool of social control through which women are kept in subordinate social positions (Brownmiller, 1975). In examining this hypothesis, the current thesis explores the role of benevolent and hostile sexism in accounting for people's responses to different types of rape (i.e. stranger vs. acquaintance rape). An examination of the literature suggests that there are general societal beliefs in the distinction between "good" and "bad" rape victims (Pollard, 1992). Interestingly, researchers have observed that benevolent sexism (BS) is related to the idealisation of women in traditional gender roles (i.e. "good" women; Glick et aI., 2000). It is, therefore, argued that individuals who idealise women in traditional roles (i.e. high BS individuals) are more likely to negatively evaluate rape victims who can be perceived as violating these norms. Nine empirical studies are presented in this thesis. Study 1 examines the potential role of BS in accounting for previously observed differences in the amount of blame attributed to stranger and acquaintance rape victims (e.g. Pollard, 1992). Studies 2 and 3 examine the psychological mechanisms that underlie the relationship between BS and victim blame in acquaintance rape situations. Studies 2 and 4 also explore the psychological mechanisms that underlie the relationship between hostile sexism (HS) and self reported rape proclivity in acquaintance rape situations (c.f. Viki, 2000). In Study 5, the relationship between BS and paternalistic chivalry (attitudes that are simultaneously courteous and restrictive to women) is examined. Studies 6 and 7 examine the role of BS in accounting for participants' responses to stranger vs. acquaintance rape perpetrators. The last two studies (Studies 8 and 9) examine the potential role of legal verdicts in moderating the relationship between BS and victim blame in acquaintance rape cases. Taken together, the results support the argument that BS provides a psychological mechanism through which differences in the amount of blame attributed to stranger and acquaintance rape victims can be explained. In contrast, HS provides a mechanism for explaining differences in self-reported proclivity to commit stranger and acquaintance rape. The thesis concludes with a summary of the findings, a discussion of the methodological limitations of the studies and suggestions of directions for future research

    The Reputations of Sir Francis Burdett

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