1,780 research outputs found

    The Ultrasonic Detection of Environmental Degradation in Adhesive Joints

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    There are many benefits to be gained when using adhesives compared with the use of more traditional joining techniques. Amongst these advantages can be listed the ability to join dissimilar materials, the uniform distribution of load over the area of the joint avoiding stress concentrations, the improvement in aesthetics and, potentially, a lower-weight for the component or structure. However several factors have retarded the more widespread use of adhesives. These principally are (i) the detrimental effect of moisture on the joint strength and (ii) the lack of a suitable non-destructive testing technique for detecting strength loss due to environmental attack. It is the latter problem that the present work addresses. The focus of this work has been to examine the bonding of aluminium alloy to aluminium alloy, using an epoxy-based adhesive

    The Correlation of Ultrasonic Measurements with Toughness Changes During the Environmental Degradation of Adhesive Joints

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    Several factors have held back the more widespread use of adhesives. These principally are the detrimental effect of moisture on bond strength and also the lack of a suitable non-destructive testing technique for detecting strength loss due to environmental attack. It is the latter problem that this work attempts to answer. The focus of this work has been to look at the bonding of aluminium to aluminium using epoxy based adhesives, as would be used in the aerospace industry. Bonding of aluminium has been performed in the aerospace industry for many years, and there has been much work done to improve the durability of this type of joint. It has been seen that the improvement in corrosion resistance that can be achieved by treating aluminium prior to bonding has a significant effect on the durability of the bond produced. This is not surprising when it is often seen that a joint which has been exposed to a hot-wet environment will fail along the interface between the aluminium and epoxy, as opposed to through the adhesive when the joint has remained dry [1]. Therefore it is this interface region that is to be examined when searching for environmental attack. The most common form of pretreatment that is used when environmental attack is a concern is anodisation of the surface to be bonded. Anodising produces a thin oxide layer on the aluminium surface, typically 1 –3 μm thick. Joints that have been anodised are considerably more durable than joints that are not anodised, but they will still exhibit interfacial failure after exposure to hot-wet environments [1]. The problem for NDT techniques is that the oxide layer which we need to inspect is orders of magnitude smaller than the bounding layers; the aluminium being 1–5mm, and the adhesive being 0.1–0.5mm thick, as shown in Figure 1. Ultrasonics has appeared to be the most promising technique for inspecting for degradation of adhesive joints, and it is this technique on which we have concentrated our efforts [2–4]

    Indium joints for cryogenic gravitational wave detectors

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    A viable technique for the preparation of highly thermal conductive joints between sapphire components in gravitational wave detectors is presented. The mechanical loss of such a joint was determined to be as low as 2 × 10−3 at 20 K and 2 × 10−2 at 300 K. The thermal noise performance of a typical joint is compared to the requirements of the Japanese gravitational wave detector, KAGRA. It is shown that using such an indium joint in the suspension system allows it to operate with low thermal noise. Additionally, results on the maximum amount of heat which can be extracted via indium joints are presented. It is found that sapphire parts, joined by means of indium, are able to remove the residual heat load in the mirrors of KAGRA

    Gaze training enhances laparoscopic technical skill acquisition and multi-tasking performance: A randomized, controlled study

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    Background: The operating room environment is replete with stressors and distractions that increase the attention demands of what are already complex psychomotor procedures. Contemporary research in other fields (e.g., sport) has revealed that gaze training interventions may support the development of robust movement skills. This current study was designed to examine the utility of gaze training for technical laparoscopic skills and to test performance under multitasking conditions. Methods: Thirty medical trainees with no laparoscopic experience were divided randomly into one of three treatment groups: gaze trained (GAZE), movement trained (MOVE), and discovery learning/control (DISCOVERY). Participants were fitted with a Mobile Eye gaze registration system, which measures eye-line of gaze at 25 Hz. Training consisted of ten repetitions of the "eye-hand coordination" task from the LAP Mentor VR laparoscopic surgical simulator while receiving instruction and video feedback (specific to each treatment condition). After training, all participants completed a control test (designed to assess learning) and a multitasking transfer test, in which they completed the procedure while performing a concurrent tone counting task. Results: Not only did the GAZE group learn more quickly than the MOVE and DISCOVERY groups (faster completion times in the control test), but the performance difference was even more pronounced when multitasking. Differences in gaze control (target locking fixations), rather than tool movement measures (tool path length), underpinned this performance advantage for GAZE training. Conclusions: These results suggest that although the GAZE intervention focused on training gaze behavior only, there were indirect benefits for movement behaviors and performance efficiency. Additionally, focusing on a single external target when learning, rather than on complex movement patterns, may have freed-up attentional resources that could be applied to concurrent cognitive tasks. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

    Understanding consumer demand for new transport technologies and services, and implications for the future of mobility

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    The transport sector is witnessing unprecedented levels of disruption. Privately owned cars that operate on internal combustion engines have been the dominant modes of passenger transport for much of the last century. However, recent advances in transport technologies and services, such as the development of autonomous vehicles, the emergence of shared mobility services, and the commercialization of alternative fuel vehicle technologies, promise to revolutionise how humans travel. The implications are profound: some have predicted the end of private car dependent Western societies, others have portended greater suburbanization than has ever been observed before. If transport systems are to fulfil current and future needs of different subpopulations, and satisfy short and long-term societal objectives, it is imperative that we comprehend the many factors that shape individual behaviour. This chapter introduces the technologies and services most likely to disrupt prevailing practices in the transport sector. We review past studies that have examined current and future demand for these new technologies and services, and their likely short and long-term impacts on extant mobility patterns. We conclude with a summary of what these new technologies and services might mean for the future of mobility.Comment: 15 pages, 0 figures, book chapte

    Substellar companions and isolated planetary mass objects from protostellar disc fragmentation

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    Self-gravitating protostellar discs are unstable to fragmentation if the gas can cool on a time scale that is short compared to the orbital period. We use a combination of hydrodynamic simulations and N-body orbit integrations to study the long term evolution of a fragmenting disc with an initial mass ratio to the star of M_disc/M_star = 0.1. For a disc which is initially unstable across a range of radii, a combination of collapse and subsequent accretion yields substellar objects with a spectrum of masses extending (for a Solar mass star) up to ~0.01 M_sun. Subsequent gravitational evolution ejects most of the lower mass objects within a few million years, leaving a small number of very massive planets or brown dwarfs in eccentric orbits at moderately small radii. Based on these results, systems such as HD 168443 -- in which the companions are close to or beyond the deuterium burning limit -- appear to be the best candidates to have formed via gravitational instability. If massive substellar companions originate from disc fragmentation, while lower-mass planetary companions originate from core accretion, the metallicity distribution of stars which host massive substellar companions at radii of ~1 au should differ from that of stars with lower mass planetary companions.Comment: 5 pages, accepted for publication in MNRA

    High prevalence of bronchiectasis is linked to HTLV-1-associated inflammatory disease.

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    BACKGROUND: Human T-lymphotropic virus type 1 (HTLV-1), a retrovirus, is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukaemia/lymphoma (ATLL). The reported association with pulmonary disease such as bronchiectasis is less certain. METHODS: A retrospective case review of a HTLV-1 seropositive cohort attending a national referral centre. The cohort was categorised into HTLV-1 symptomatic patients (SPs) (ATLL, HAM/TSP, Strongyloidiasis and HTLV associated inflammatory disease (HAID)) and HTLV-1 asymptomatic carriers (ACs). The cohort was reviewed for diagnosis of bronchiectasis. RESULT: 34/246 ACs and 30/167 SPs had been investigated for respiratory symptoms by computer tomography (CT) with productive cough +/- recurrent chest infections the predominant indications. Bronchiectasis was diagnosed in one AC (1/246) and 13 SPs (2 HAID, 1 ATLL, 10 HAM/TSP) (13/167, RR 19.2 95 % CI 2.5-14.5, p = 0.004) with high resolution CT. In the multivariate analysis ethnicity (p = 0.02) and disease state (p < 0.001) were independent predictors for bronchiectasis. The relative risk of bronchiectasis in SPs was 19.2 (95 % CI 2.5-14.5, p = 0.004) and in HAM/TSP patients compared with all other categories 8.4 (95 % CI 2.7-26.1, p = 0.0002). Subjects not of African/Afro-Caribbean ethnicity had an increased prevalence of bronchiectasis (RR 3.45 95 % 1.2-9.7, p = 0.02). CONCLUSIONS: Bronchiectasis was common in the cohort (3.4 %). Risk factors were a prior diagnosis of HAM/TSP and ethnicity but not HTLV-1 viral load, age and gender. The spectrum of HTLV-associated disease should now include bronchiectasis and HTLV serology should be considered in patients with unexplained bronchiectasis

    A Renewed Social Democracy for an 'Age of Internationalism':An Interpretivist Account of New Labour’s Foreign Policy

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    This paper employs an interpretive approach to explore New Labour’s use of social scientific theories in developing its foreign policy. After situating New Labour in the broad tradition of social democracy, it outlines the beliefs that most social democrats shared about the values of internationalism, international community and moral leadership. Taking these concepts in turn, the paper then considers how New Labour modified their content in response to issues raised by ‘New Times’. In so doing, it problematizes New Labour’s responses by revealing that they drew on ideas taken from complex interdependence theory, communitarianism and democratic peace theory respectively. The paper then examines how these theories, in conjunction with the reformulation of its foreign policy, influenced New Labour’s transformation of the three values, before concluding with a brief examination of the dilemmas arising from this process

    Critical Language and Discourse Awareness in Management Education

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    Communication and, through it, language have become key elements of business and organizational life. How organizations interact within their walls and with the outside world fundamentally affects business processes, creating organizational culture, shaping public perceptions, and influencing consumer choices. This essay calls for a greater acknowledgment of language and communication and suggests that management educators may want to review how they are incorporated in management education curricula. Expanding on the skill-based approach typically adopted in business school classes, the essay points to the utility of exposing business students to the dual function of language as a means of doing work and as a social action that constitutes social reality. Drawing on examples from scholarship in linguistics and discourse analysis, the essay demonstrates that the ability to notice, identify, and reflect on linguistic and discourse practices is a crucial managerial skill. Nurturing such analytical and thinking skills enables people to become not only better communicators but also critical thinkers able to understand and challenge when social control, power, or injustice is enacted in organizations
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