1,722,105 research outputs found
Time-modulated inerters as building blocks for nonreciprocal mechanical devices
No full textIn this work, we discuss the realization of mechanical devices with non-reciprocal attributes enabled by inertia-amplifying, time-modulated mechanisms. Our fundamental building-block features a mass, connected to a fixed ground through a spring and to a moving base through a mechanism-based inerter. Through analytical derivations and numerical simulations, we provide details on the nonlinear dynamics of such system. We demonstrate that providing a time modulation to the inerter's base produces two additions on the dynamics of the main spring–mass oscillator: (i) an effective time-modulated mass term, and (ii) a time varying force term; both quantities are functions of the modulating frequency. With specific choices of parameters, the modulation-induced force term – that represents one of the main drawbacks in most experimental realizations of purely time-modulated systems – vanishes and we are left with an effective time-varying mass. We then illustrate that this building block can be leveraged to realize non-reciprocal wave manipulation devices, and concentrate on a non-reciprocal beam-like waveguide. The simple design and the clean performance of our system makes it an attractive candidate for the realization of fully mechanical non-reciprocal devices
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
User gait biometrics in smart ambient applications through wearable accelerometer signals: an analysis of the influence of training setup on recognition accuracy
No full textGait recognition can exploit the signals from wearables, e.g., the accelerometers embedded in smart devices. At present, this kind of recognition mostly underlies subject verification: the incoming probe is compared only with the templates in the system gallery that belong to the claimed identity. For instance, several proposals tackle the continuous recognition of the device owner to detect possible theft or loss. In this case, assuming a short time between the gallery template acquisition and the probe is reasonable. This work rather investigates the viability of a wider range of applications including identification (comparison with a whole system gallery) in the medium-long term. The first contribution is a procedure for extraction and two-phase selection of the most relevant aggregate features from a gait signal. A model is trained for each identity using Logistic Regression. The second contribution is the experiments investigating the effect of the variability of the gait pattern in time. In particular, the recognition performance is influenced by the benchmark partition into training and testing sets when more acquisition sessions are available, like in the exploited ZJU-gaitacc dataset. When close-in-time acquisition data is only available, the results seem to suggest re-identification (short time among captures) as the most promising application for this kind of recognition. The exclusive use of different dataset sessions for training and testing can rather better highlight the dramatic effect of trait variability on the measured performance. This suggests acquiring enrollment data in more sessions when the intended use is in medium-long term applications of smart ambient intelligence
Towards the suitability of gait wearable signal processing for long term recognition
No full textOne of the present approaches to gait recognition exploits the signals captured by wearable sensors, especially the accelerometers embedded in modern smartphones. However, the different speed, the ground slope, or simply the time lapse between captures cause variations that negatively affect long term recognition in a dramatic way. The proposed procedure aims at extracting gait characteristics that are as invariant as possible, and therefore useful for accurate long term recognition. The experiments compare the performance of the proposal with others in state-of-the-art that use the same benchmark, namely the ZJU-gaitacc dataset. This dataset includes a high number of samples per subject, captured in two time-separated sessions. This allows to assess the performance of the proposed method also in the long term, i.e., when comparing templates captured in different times. Most works using the same benchmark so far have not exploited both sessions. They use samples captured in the same time, constraining the use of this trait to continuous recognition, e.g., of the smartphone owner. The obtained results testify that, in this condition, the proposed feature-based method outperforms competitors in the current literature. The experiments also compare the results from a session-based partition with those obtained from a training that mixes-up samples from different sessions. As expected, the latter strategy can dramatically improve the measured performance. The significantly different results seem to suggest that the session-based partition, when feasible, can provide more realistic results, closer to the real-world application context when behavioural traits are involved in the medium/long term. The same results seem also to testify that there is still need to improve the accuracy of gait recognition via wearable sensors. This calls for further investigation of the problems related to the variability over time in the pattern of individual gait signals
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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