1,721,138 research outputs found
Comment on: Thompson D.R. & Darbyshire P. (2013) Is academic nursing being sabotaged by its own killer elite?
No full textComment on: Thompson D.R. & Darbyshire P. (2013) Is academic nursing being sabotaged by its own killer elite
Investigations of propagating wave types in railway tracks at high frequencies
No full textAt low frequencies waves propagate in a rail as bending, extensional or torsional waves. At higher frequencies, above about 1.5 kHz, the rail cross-section deforms and many higher order wave types exist. This cross-section deformation has to be taken into account for an accurate evaluation of the dispersion properties at high frequencies. Simulation results in the literature show that a multiplicity of wave modes is possible within this high-frequency range. In this work, wave types that propagate primarily through separate regions of the rail cross-section are investigated for frequencies up to 80 kHz. Two numerical methods are applied to obtain the dispersion properties for a railway track model including rail pads as a continuous foundation. These are a conventional finite element (FE) method and a wavenumber finite element (WFE) method, each of which can include the effects of cross-sectional deformation. In order to validate the predicted results, experiments were performed on a short test track using an impact hammer and accelerometers. Additional measurements used piezoceramic transducers to excite the rail at higher frequencies. The results are compared with simulations in terms of the group velocity and they present very good agreement. From this comparison, it is identified which wave types predominantly propagate on various regions of the rail cross-section
Decay rates of propagating waves in railway tracks at high frequencies
No full textIn order to understand long range wave propagation in railway tracks, it is required to identify how far vibrations can travel along a rail. To answer this question, the attenuation characteristics of the main propagating waves are required as a function of distance. In this work, decay rates of propagating waves in railway tracks are investigated for frequencies up to 80 kHz. A numerical method called the wavenumber finite element (WFE) method is utilized to predict decay rates for a rail on a continuous foundation. Damping is introduced in this track model by the material damping in the rail and in the foundation. In order to improve the simulated results, the frequency dependent damping loss factor of a rail has been measured up to 80 kHz on short rail samples. From this simulation, the relative importance of the rail and support damping for the long range wave propagation is determined. In order to validate the simulated results, a field measurement has been performed on an operational railway track. From this experiment, train-induced rail vibrations have been acquired for several running trains travelling over a long section of rail. The measured results are presented for comparison with the output of the simulations and good agreement is found between them.<br/
Wave reflection and transmission due to defects in infinite structural waveguides at high frequencies
No full textIn waveguide structures, waves may be partially reflected by local non-uniformities such as cracks and other defects. The reflection and transmission characteristics associated with the presence of a discontinuity may be used, in principle, to give some indication of both the location and size of the defect. A combined spectral element and finite element (SE/FE) method has been used previously to investigate the effects of local non-uniformities at relatively low frequencies. However, for analysis at higher frequencies, where complex deformation of the waveguide occurs, it is necessary to extend this approach. Such high frequency analysis is necessary if small defects are to be located within the waveguide cross-section. In order to investigate wave propagation at higher frequencies, a combined spectral super element and finite element (SSE/FE) method is presented. This method allows the transmission, reflection and wave conversion at discontinuities to be determined for complex waveguides. As an example of the use of this method, wave reflection and transmission in rails are estimated at frequencies between 20 and 40 kHz for various notional sawcut-like defects of progressively increasing size. This shows the feasibility of the approach for realistic waveguides. However, from these simulations it is shown that defects have to be quite large before they can be detected using a single transducer position on the rail cross-section using train-induced vibratio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development of a reliable and valid Chinese version of the Diabetes Empowerment Scale
No full textObjective: To translate the Diabetes Empowerment Scale (DES) into Chinese and establish its psychometric properties among Hong Kong Chinese people. Research Design and Methods: A two-stage study design, incorporating qualitative and quantitative components, determined the cultural equivalency and content validity of the translated scale and established the psychometric properties of the Chinese DES (C-DES) in 207 patients. Results: Psychometric analysis supported the reliability and validity of the 20-item Chinese DES (C-DES-20) and five subscales: overcoming barriers ( = 0.89), determining suitable methods ( = 0.79), achieving goals ( = 0.78), obtaining support ( = 0.78), and coping ( = 0.76). The test-retest reliability of the intraclass correlations was satisfactory when a subsample of 20 patients was tested after a 2-week interval. There was criterion validity between the global scale and metabolic control (HbA1c) of respondents with type 2 diabetes (P = 0.03). Conclusions: The C-DES-20 is a reliable and valid outcome measure for patient education and psychosocial interventions among Hong Kong Chinese people with diabetes
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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