570 resultados para Twist drills


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We report a strong polarization dependent coupling behavior of fiber Bragg gratings with excessively tilted structures up to 81°. This unique property has been utilized to implement a novel twist sensor, showing high torsion sensitivity. The twist induced light coupling interchange between the two birefringence modes makes it possible to interrogate such a sensor using low-cost intensity demodulation technique. © 2006 IEEE.

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We report a novel in-fibre twist sensor utilising strong polarisation dependent coupling behaviour of fiber Bragg grating with 81° tilted structure. The demonstrated twist sensor has shown high torsion sensitivity and capability of direction recognition.

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We experimentally demonstrated a highly sensitive twist sensor system based on a 45° and an 81° tilted fibre grating (TFG). The 81°-TFG has a set of dual-peaks that are due to the birefringence induced by its extremely tilted structure. When the 81°-TFG subjected to twist, the coupling to the two peaks would interchange from each other, providing a mechanism to measure and monitor the twist. We have investigated the performance of the sensor system by three interrogation methods (spectral, power-measurement and voltage-measurement). The experimental results clearly show that the 81°-TFG and the 45°-TFG could be combined forming a full fibre twist sensor system capable of not just measuring the magnitude but also recognising the direction of the applied twist.

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Acknowledgements The FFTEM data were obtained at the (Cryo) TEM facility at the Liquid Crystal Institute, Kent State University, supported by the Ohio Research Scholars Program Research Cluster on Surfaces in Advanced Materials. ODL acknowledges the support of NSF DMR-1410378 grant. The authors are grateful for financial support from MINECO/FEDER MAT2015-66208-C3-2-P and from the Gobierno Vasco (GI/IT-449-10)

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Frederick Douglas was a reader of and writer on the nineteenth-century political and social texts and contexts of oppression, which he experienced at home and witnesed while in Ireland and Britain, 1845-47. This thesis is unique in its identification of several surprising lacunae in the research and critical evaluation of Frederick Douglass’ activities of reading and writing and the texts and contexts that supported these activities. This thesis takes Douglass’ relationship with Ireland and the Irish as its starting point, and offers several moments in the transnational space engendered by Douglass’ readerly and writerly experience of the transatlantic axes of Ireland, Britain and America. This thesis draws upon archival research to recover information regarding Douglass’ trip and subjects his reading and writing on Ireland and the Irish to the critical rigours of narratolgical, cultural and discourse analysis. One lacuna is Douglass’ favourite and neglected school primer, the Columbian Orator, which Douglass signified upon across his autobiographical project. The speech by the Irish patriot and exile, Arthur O’Connor, included in the Orator, is crucial to Douglass’ understanding and expression of justice and equality. Genette’s narratological analysis gives theoretical traction to the ways in which, in his autobiographical representations of his British trip, Douglass recalibrates his autobiographies to reflect his changing perspectives on his life and work. Contrary to popular assumptions, Douglass did, in two letters to Garrison address and comment on Irish poverty. This thesis interrogates the strategic anglophilia of these letters. While the World’s Temperance Convention (WTC) refused to discuss African- American slavery, analysis of Douglass’ speech in Covent Garden and of the paratextual apparatus of the published proceedings of the WTC demonstrates the impossibility of separating these closely interrelated reform causes. When a newly discovered poem from Waterford that admonished the city for its disregard for Douglass’ message is juxtaposed with an uncomfortable moment in Cork, we understand that Douglass became a pawn to bolster sectarian rivalries between nationalist and establishment factions. Though Douglass believed imperial politics was the best vehicle for modernity, he recognised that it had failed Ireland: consequently, in Thoughts and Recollections of a Trip to Ireland (1886), he advocates for Home Rule for Ireland.

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o scopo di questa tesi è quello di fornire un'analisi esaustiva del romanzo thriller Twist di Harkaitz Cano e proporre una traduzione del primo capitolo «Cambalache, 1983». Quest'ultimo, in particolare, offre un esempio dello stile di scrittura di Cano e rappresenta allo stesso tempo una notevole sfida per il traduttore e una coinvolgente lettura. La proposta di traduzione e l'analisi delle difficoltà incontrate nel corso del processo traduttivo sono precedute prima da una presentazione della produzione letteraria dell'autore e del contesto storico-sociale in cui nasce il romanzo, e poi da un breve ma interessante approfondimento su trama, stile e temi dell'opera, in cui non mancano collegamenti e spunti di riflessione sulla storia, sulla cultura e sulla società basca e spagnola.

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The book within which this chapter appears is published as a research reference book (not a coursework textbook) on Management Information Systems (MIS) for seniors or graduate students in Chinese universities. It is hoped that this chapter, along with the others, will be helpful to MIS scholars and PhD/Masters research students in China who seek understanding of several central Information Systems (IS) research topics and related issues. The subject of this chapter - ‘Evaluating Information Systems’ - is broad, and cannot be addressed in its entirety in any depth within a single book chapter. The chapter proceeds from the truism that organizations have limited resources and those resources need to be invested in a way that provides greatest benefit to the organization. IT expenditure represents a substantial portion of any organization’s investment budget and IT related innovations have broad organizational impacts. Evaluation of the impact of this major investment is essential to justify this expenditure both pre- and post-investment. Evaluation is also important to prioritize possible improvements. The chapter (and most of the literature reviewed herein) admittedly assumes a blackbox view of IS/IT1, emphasizing measures of its consequences (e.g. for organizational performance or the economy) or perceptions of its quality from a user perspective. This reflects the MIS emphasis – a ‘management’ emphasis rather than a software engineering emphasis2, where a software engineering emphasis might be on the technical characteristics and technical performance. Though a black-box approach limits diagnostic specificity of findings from a technical perspective, it offers many benefits. In addition to superior management information, these benefits may include economy of measurement and comparability of findings (e.g. see Part 4 on Benchmarking IS). The chapter does not purport to be a comprehensive treatment of the relevant literature. It does, however, reflect many of the more influential works, and a representative range of important writings in the area. The author has been somewhat opportunistic in Part 2, employing a single journal – The Journal of Strategic Information Systems – to derive a classification of literature in the broader domain. Nonetheless, the arguments for this approach are believed to be sound, and the value from this exercise real. The chapter drills down from the general to the specific. It commences with a highlevel overview of the general topic area. This is achieved in 2 parts: - Part 1 addressing existing research in the more comprehensive IS research outlets (e.g. MISQ, JAIS, ISR, JMIS, ICIS), and Part 2 addressing existing research in a key specialist outlet (i.e. Journal of Strategic Information Systems). Subsequently, in Part 3, the chapter narrows to focus on the sub-topic ‘Information Systems Success Measurement’; then drilling deeper to become even more focused in Part 4 on ‘Benchmarking Information Systems’. In other words, the chapter drills down from Parts 1&2 Value of IS, to Part 3 Measuring Information Systems Success, to Part 4 Benchmarking IS. While the commencing Parts (1&2) are by definition broadly relevant to the chapter topic, the subsequent, more focused Parts (3 and 4) admittedly reflect the author’s more specific interests. Thus, the three chapter foci – value of IS, measuring IS success, and benchmarking IS - are not mutually exclusive, but, rather, each subsequent focus is in most respects a sub-set of the former. Parts 1&2, ‘the Value of IS’, take a broad view, with much emphasis on ‘the business Value of IS’, or the relationship between information technology and organizational performance. Part 3, ‘Information System Success Measurement’, focuses more specifically on measures and constructs employed in empirical research into the drivers of IS success (ISS). (DeLone and McLean 1992) inventoried and rationalized disparate prior measures of ISS into 6 constructs – System Quality, Information Quality, Individual Impact, Organizational Impact, Satisfaction and Use (later suggesting a 7th construct – Service Quality (DeLone and McLean 2003)). These 6 constructs have been used extensively, individually or in some combination, as the dependent variable in research seeking to better understand the important antecedents or drivers of IS Success. Part 3 reviews this body of work. Part 4, ‘Benchmarking Information Systems’, drills deeper again, focusing more specifically on a measure of the IS that can be used as a ‘benchmark’3. This section consolidates and extends the work of the author and his colleagues4 to derive a robust, validated IS-Impact measurement model for benchmarking contemporary Information Systems (IS). Though IS-Impact, like ISS, has potential value in empirical, causal research, its design and validation has emphasized its role and value as a comparator; a measure that is simple, robust and generalizable and which yields results that are as far as possible comparable across time, across stakeholders, and across differing systems and systems contexts.

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The buckling strength of a new cold-formed hollow flange channel section known as LiteSteel beam (LSB) is governed by lateral distortional buckling characterised by simultaneous lateral deflection, twist and web distortion for its intermediate spans. Recent research has developed a modified elastic lateral buckling moment equation to allow for lateral distortional buckling effects. However, it is limited to a uniform moment distribution condition that rarely exists in practice. Transverse loading introduces a non-uniform bending moment distribution, which is also often applied above or below the shear centre (load height). These loading conditions are known to have significant effects on the lateral buckling strength of beams. Many steel design codes have adopted equivalent uniform moment distribution and load height factors to allow for these effects. But they were derived mostly based on data for conventional hot-rolled, doubly symmetric I-beams subject to lateral torsional buckling. The moment distribution and load height effects of transverse loading for LSBs, and the suitability of the current design modification factors to accommodate these effects for LSBs is not known. This paper presents the details of a research study based on finite element analyses on the elastic lateral buckling strength of simply supported LSBs subject to transverse loading. It discusses the suitability of the current steel design code modification factors, and provides suitable recommendations for simply supported LSBs subject to transverse loading.

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The flexural capacity of of a new cold-formed hollow flange channel section known as LiteSteel beam (LSB) is limited by lateral distortional buckling for intermediate spans, which is characterised by simultaneous lateral deflection, twist and web distortion. Recent research has developed suitable design rules for the member capacity of LSBs. However, they are limited to a uniform moment distribution that rarely exists in practice. Many steel design codes have adopted equivalent uniform moment distribution factors to accommodate the effect of non-uniform moment distributions in design. But they were derived mostly based on the data for conventional hot-rolled, doubly symmetric I-beams subject to lateral torsional buckling. The effect of moment distribution for LSBs, and the suitability of the current steel design code rules to include this effect for LSBs are not yet known. This paper presents the details of a research study based on finite element analyses of the lateral buckling strength of simply supported LSBs subject to moment gradient effects. It also presents the details of a number of LSB lateral buckling experiments undertaken to validate the results of finite element analyses. Finally, it discusses the suitability of the current design methods, and provides design recommendations for simply supported LSBs subject to moment gradient effects.

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Low back pain is an increasing problem in industrialised countries and although it is a major socio-economic problem in terms of medical costs and lost productivity, relatively little is known about the processes underlying the development of the condition. This is in part due to the complex interactions between bone, muscle, nerves and other soft tissues of the spine, and the fact that direct observation and/or measurement of the human spine is not possible using non-invasive techniques. Biomechanical models have been used extensively to estimate the forces and moments experienced by the spine. These models provide a means of estimating the internal parameters which can not be measured directly. However, application of most of the models currently available is restricted to tasks resembling those for which the model was designed due to the simplified representation of the anatomy. The aim of this research was to develop a biomechanical model to investigate the changes in forces and moments which are induced by muscle injury. In order to accurately simulate muscle injuries a detailed quasi-static three dimensional model representing the anatomy of the lumbar spine was developed. This model includes the nine major force generating muscles of the region (erector spinae, comprising the longissimus thoracis and iliocostalis lumborum; multifidus; quadratus lumborum; latissimus dorsi; transverse abdominis; internal oblique and external oblique), as well as the thoracolumbar fascia through which the transverse abdominis and parts of the internal oblique and latissimus dorsi muscles attach to the spine. The muscles included in the model have been represented using 170 muscle fascicles each having their own force generating characteristics and lines of action. Particular attention has been paid to ensuring the muscle lines of action are anatomically realistic, particularly for muscles which have broad attachments (e.g. internal and external obliques), muscles which attach to the spine via the thoracolumbar fascia (e.g. transverse abdominis), and muscles whose paths are altered by bony constraints such as the rib cage (e.g. iliocostalis lumborum pars thoracis and parts of the longissimus thoracis pars thoracis). In this endeavour, a separate sub-model which accounts for the shape of the torso by modelling it as a series of ellipses has been developed to model the lines of action of the oblique muscles. Likewise, a separate sub-model of the thoracolumbar fascia has also been developed which accounts for the middle and posterior layers of the fascia, and ensures that the line of action of the posterior layer is related to the size and shape of the erector spinae muscle. Published muscle activation data are used to enable the model to predict the maximum forces and moments that may be generated by the muscles. These predictions are validated against published experimental studies reporting maximum isometric moments for a variety of exertions. The model performs well for fiexion, extension and lateral bend exertions, but underpredicts the axial twist moments that may be developed. This discrepancy is most likely the result of differences between the experimental methodology and the modelled task. The application of the model is illustrated using examples of muscle injuries created by surgical procedures. The three examples used represent a posterior surgical approach to the spine, an anterior approach to the spine and uni-lateral total hip replacement surgery. Although the three examples simulate different muscle injuries, all demonstrate the production of significant asymmetrical moments and/or reduced joint compression following surgical intervention. This result has implications for patient rehabilitation and the potential for further injury to the spine. The development and application of the model has highlighted a number of areas where current knowledge is deficient. These include muscle activation levels for tasks in postures other than upright standing, changes in spinal kinematics following surgical procedures such as spinal fusion or fixation, and a general lack of understanding of how the body adjusts to muscle injuries with respect to muscle activation patterns and levels, rate of recovery from temporary injuries and compensatory actions by other muscles. Thus the comprehensive and innovative anatomical model which has been developed not only provides a tool to predict the forces and moments experienced by the intervertebral joints of the spine, but also highlights areas where further clinical research is required.

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The word “queer” is a slippery one; its etymology is uncertain, and academic and popular usage attributes conflicting meanings to the word. By the mid-nineteenth century, “queer” was used as a pejorative term for a (male) homosexual. This negative connotation continues when it becomes a term for homophobic abuse. In recent years, “queer” has taken on additional uses: as an all encompassing term for culturally marginalised sexualities – gay, lesbian, trans, bi, and intersex (“GLBTI”) – and as a theoretical strategy which deconstructs binary oppositions that govern identity formation. Tracing its history, the Oxford English Dictionary notes that the earliest references to “queer” may have appeared in the sixteenth century. These early examples of queer carried negative connotations such as “vulgar,” “bad,” “worthless,” “strange,” or “odd” and such associations continued until the mid-twentieth century. The early nineteenth century, and perhaps earlier, employed “queer” as a verb, meaning to “to put out of order,” “to spoil”, “to interfere with”. The adjectival form also began to emerge during this time to refer to a person’s condition as being “not normal,” “out of sorts” or to cause a person “to feel queer” meaning “to disconcert, perturb, unsettle.” According to Eve Sedgwick (1993), “the word ‘queer’ itself means across – it comes from the Indo-European root – twerkw, which also yields the German quer (traverse), Latin torquere (to twist), English athwart . . . it is relational and strange.” Despite the gaps in the lineage and changes in usage, meaning and grammatical form, “queer” as a political and theoretical strategy has benefited from its diverse origins. It refuses to settle comfortably into a single classification, preferring instead to traverse several categories that would otherwise attempt to stabilise notions of chromosomal sex, gender and sexuality.

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High Fashion is a practice-led research enquiry that examines the processes involved in producing a no-budget film of high aesthetic standards that can confidently compete in the global film festival market, and to reflect on the production techniques tested during the making of the film. The practical outcome of the research is a twenty-five minute short drama. It incorporates a large cast and crew, original designer clothing, extravagant sets, and a popular soundtrack. The thesis considers how over one hundred professionals volunteered their time, expertise, and equipment to help produce the film. The thesis also examines the many obstacles encountered while producing the film and how these were overcome. It is written for the student filmmaker as a guide to "learn by doing."

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The LiteSteel Beam (LSB) is a new hollow flange section developed by OneSteel Australian Tube Mills using their patented dual electric resistance welding and automated continuous roll-forming technologies. It has a unique geometry consisting of torsionally rigid rectangular hollow flanges and a relatively slender web. It has found increasing popularity in residential, industrial and commercial buildings as flexural members. The LSB is considerably lighter than traditional hot-rolled steel beams and provides both structural and construction efficiencies. However, the LSB flexural members are subjected to a relatively new lateral distortional buckling mode, which reduces their member moment capacities. Unlike the commonly observed lateral torsional buckling of steel beams, the lateral distortional buckling of LSBs is characterised by simultaneous lateral defection, twist and cross sectional change due to web distortion. The current design rules in AS/NZS 4600 (SA, 2005) for flexural members subject to lateral distortional buckling were found to be conservative by about 8% in the inelastic buckling region. Therefore, a new design rule was developed for LSBs subject to lateral distortional buckling based on finite element analyses of LSBs. The effect of section geometry was then considered and several geometrical parameters were used to develop an advanced set of design rules. This paper presents the details of the finite element analyses and the design curve development for hollow flange sections subject to lateral distortional buckling.

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The LiteSteel Beam (LSB) is a new hollow flange channel section developed by OneSteel Australian Tube Mills using a patented Dual Electric Resistance Welding technique. The LSB has a unique geometry consisting of torsionally rigid rectangular hollow flanges and a relatively slender web. It is commonly used as rafters, floor joists and bearers and roof beams in residential, industrial and commercial buildings. It is on average 40% lighter than traditional hot-rolled steel beams of equivalent performance. The LSB flexural members are subjected to a relatively new Lateral Distortional Buckling mode, which reduces the member moment capacity. Unlike the commonly observed lateral torsional buckling of steel beams, lateral distortional buckling of LSBs is characterised by simultaneous lateral deflection, twist and web distortion. Current member moment capacity design rules for lateral distortional buckling in AS/NZS 4600 (SA, 2005) do not include the effect of section geometry of hollow flange beams although its effect is considered to be important. Therefore detailed experimental and finite element analyses (FEA) were carried out to investigate the lateral distortional buckling behaviour of LSBs including the effect of section geometry. The results showed that the current design rules in AS/NZS 4600 (SA, 2005) are over-conservative in the inelastic lateral buckling region. New improved design rules were therefore developed for LSBs based on both FEA and experimental results. A geometrical parameter (K) defined as the ratio of the flange torsional rigidity to the major axis flexural rigidity of the web (GJf/EIxweb) was identified as the critical parameter affecting the lateral distortional buckling of hollow flange beams. The effect of section geometry was then included in the new design rules using the new parameter (K). The new design rule developed by including this parameter was found to be accurate in calculating the member moment capacities of not only LSBs, but also other types of hollow flange steel beams such as Hollow Flange Beams (HFBs), Monosymmetric Hollow Flange Beams (MHFBs) and Rectangular Hollow Flange Beams (RHFBs). The inelastic reserve bending capacity of LSBs has not been investigated yet although the section moment capacity tests of LSBs in the past revealed that inelastic reserve bending capacity is present in LSBs. However, the Australian and American cold-formed steel design codes limit them to the first yield moment. Therefore both experimental and FEA were carried out to investigate the section moment capacity behaviour of LSBs. A comparison of the section moment capacity results from FEA, experiments and current cold-formed steel design codes showed that compact and non-compact LSB sections classified based on AS 4100 (SA, 1998) have some inelastic reserve capacity while slender LSBs do not have any inelastic reserve capacity beyond their first yield moment. It was found that Shifferaw and Schafer’s (2008) proposed equations and Eurocode 3 Part 1.3 (ECS, 2006) design equations can be used to include the inelastic bending capacities of compact and non-compact LSBs in design. As a simple design approach, the section moment capacity of compact LSB sections can be taken as 1.10 times their first yield moment while it is the first yield moment for non-compact sections. For slender LSB sections, current cold-formed steel codes can be used to predict their section moment capacities. It was believed that the use of transverse web stiffeners could improve the lateral distortional buckling moment capacities of LSBs. However, currently there are no design equations to predict the elastic lateral distortional buckling and member moment capacities of LSBs with web stiffeners under uniform moment conditions. Therefore, a detailed study was conducted using FEA to simulate both experimental and ideal conditions of LSB flexural members. It was shown that the use of 3 to 5 mm steel plate stiffeners welded or screwed to the inner faces of the top and bottom flanges of LSBs at third span points and supports provided an optimum web stiffener arrangement. Suitable design rules were developed to calculate the improved elastic buckling and ultimate moment capacities of LSBs with these optimum web stiffeners. A design rule using the geometrical parameter K was also developed to improve the accuracy of ultimate moment capacity predictions. This thesis presents the details and results of the experimental and numerical studies of the section and member moment capacities of LSBs conducted in this research. It includes the recommendations made regarding the accuracy of current design rules as well as the new design rules for lateral distortional buckling. The new design rules include the effects of section geometry of hollow flange steel beams. This thesis also developed a method of using web stiffeners to reduce the lateral distortional buckling effects, and associated design rules to calculate the improved moment capacities.

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This paper presents evidence of an apparent connection between ball lightning and a green fireball. On the evening of the 16th May 2006 at least three fireballs were seen by many people in the skies of Queensland, Australia. One of the fireballs was seen passing over the Great Divide about 120 km west of Brisbane, and soon after, a luminous green ball about 30 cm in diameter was seen rolling down the slope of the Great Divide. A detailed description given by a witness indicates that the phenomenon was probably a highly luminous form of ball lightning. An hypothesis presented in this paper is that the passage of the Queensland fireball meteor created an electrically conductive path between the ionosphere and ground, providing energy for the ball lightning phenomenon. A strong similarity is noted between the Queensland fireball and the Pasamonte fireball seen in New Mexico in 1933. Both meteors exhibit a twist in the tail that could be explained by hydrodynamic forces. The possibility that multiple sightings of fireballs across South East Queensland were produced owing to fragments from comet 73P Schwassmann-Wachmann 3 is discussed.