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31.
Goktug T. Cinar Pedro M.N. Sequeira Jose C. Principe 《Journal of The Franklin Institute》2018,355(4):1638-1662
In this paper we develop a new framework for time series segmentation based on a Hierarchical Linear Dynamical System (HLDS), and test its performance on monophonic and polyphonic musical note recognition. The center piece of our approach is the inclusion of constraints in the filter topology, instead of on the cost function as normally done in machine learning. Just by slowing down the dynamics of the top layer of an augmented (multilayer) state model, which is still compatible with the recursive update equation proposed originally by Kalman, the system learns directly from data all the musical notes, without labels, effectively creating a time series clustering algorithm that does not require segmentation. We analyze the HLDS properties and show that it provides better classification accuracy compared to current state-of-the-art approaches. 相似文献
32.
Jose M. Saavedra Antonio García-Hermoso Yolanda Escalante Ana M. Dominguez Raul Arellano Fernando Navarro 《Journal of sports sciences》2013,31(19):1783-1789
AbstractThe purpose of this study was to investigate the association between relay exchange block time and final performance in 4 × 100-m and 4 × 200-m freestyle and 4 × 100-m medley relays as a function of sex (men and women) and classification (medallists and non-medallists) in international competitions. Nineteen international competitions covering a 13-year period (2000–2012) were analysed retrospectively. The data corresponded to a total of 827 team relay histories (407 men, 420 women). Kruskal–Wallis and Mann–Whitney tests were performed to determine any differences by sex, classification, and event. Similarly, the relationship between the exchange block times and final performance was examined by means of a Pearson correlation analysis. In the three events, the men’s exchange block times were shorter than those of the women (η2 = 0.049–0.109; P < 0.001). The exchange block time was especially relevant for the women’s relay medallists in the 4 × 100-m freestyle (r = 0.306, P = 0.021) and 4 × 100-m medley (r = 0.385, P = 0.011), while for men the relationship was clearer for the non-medallists. These results suggest that the exchange block time should be considered as one of the performance parameters of swimming relay starts, and thus should be included explicitly as part of training. In particular, the coach could design training targeted at standardising an optimal exchange block time equal to or less than that expected for other teams in the competition. 相似文献
33.
Hector Hernández-Davo Tomás Urbán Jose Manuel Sarabia Casto Juan-Recio Francisco Javier Moreno 《Journal of sports sciences》2013,31(14):1383-1388
AbstractVariable practice has been shown to be an effective strategy to improve open motor skills. However, the usefulness of this procedure in closed motor skills remains controversial. The following study has the objective of analysing the effects of variability practice in the improvement of a closed skill. The skill studied has been the tennis serve. Thirty young tennis players (13 ± 1.52 years), divided in two groups, took part in this study. One group practiced in variable conditions and the other group in consistency conditions. Both groups performed 12 training sessions (60 serves/session). The variable practice group improved their accuracy significantly compared with the consistency group (F3.25 = 3.078; P = 0.035). The velocity of serve increased after training in both groups (F3.25 = 15.890; P = 0.001). The practice in variable conditions seems to be effective in improving the performance of the tennis serve. 相似文献
34.
Pedro Pérez-Soriano Salvador Llana-Belloch Gaspar Morey-Klapsing Jose Antonio Perez-Turpin Juan Manuel Cortell-Tormo 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):245-257
Shock absorption and stability during landings is provided by both, gymnast ability and mat properties. The aims of this study were to determine the influence of different mat constructions on their energy absorption and stability capabilities, and to analyse how these properties affect gymnast's plantar pressures as well as subjective mat perception during landing. Six mats were tested using a standard mechanical drop test. In addition, plantar pressures and subjective perception during landing were obtained from 15 expert gymnasts. The different mats influenced plantar pressures and gymnasts' subjective perception during landing of gymnasts. Significant correlations between plantar pressures at the medial metatarsal and lateral metatarsal zones of the gymnasts' feet with the different shock absorption characteristics of the mats were found. However, subjective perception tests were not able to discriminate mat functionality between the six mats as no significant correlations between the mechanical mat properties with the subjective perception of these properties were found. This study demonstrated that plantar pressures are a useful tool for discriminating different landing mats. Using similar approaches, ideally including kinematics as well, could help us in our understanding about the influences of different mats upon gymnast-mat interaction. 相似文献
35.
The performance of 43 Hispanic engineering and science majors on a task that consists of reading a sentence describing a mathematical relationship between two variables, and then writing an equation describing the relationship, is investigated in both English and Spanish. Results are compared with grade point average and with language proficiency. Comparison of the bilingual group to a monolingual group consisting of 52 engineering and science students shows that performance, as measured by either the mathematical translation task or grade point average, is more strongly correlated with language proficiency for the bilingual group. Clinical interviews conducted with samples from each group reveal large differences in the interpretation of the mathematical task between Hispanics and monolinguals. Suggestions are made for the improvement of the technical education of Hispanics. 相似文献
36.
Jenaro Guisasola Jose L. Zubimendi Jose M. Almudí Mikel Ceberio 《Science & Education》2002,11(3):247-261
There are few didactic studies concerning the difficulties met by students inunderstanding the meaning of capacitance in a charged body. However, theunderstanding of capacitance can be a good indicator of the Students' learningof electrostatic theory in general. To describe Students' difficulties in learningthis concept we have considered, on the one hand, that individuals constructmental representations in order to help their understanding of the way a physicalsystem works under varied circumstances. On the other hand, a critical study ofthe history and epistemology of science is likely to enlighten us teachers andresearchers about the presence of qualitative leaps in the evolution of a concept.Thus, the consideration by teachers of these `discontinuities between meaningsfor the same concept, may lead them to understand Students' difficulties on learningit. We developed a historical study of the development of the capacitance conceptand an empirical study with students to identify historical and learning difficulties.The results obtained seem to show that most of the students who reason aboutaspects related to the charge of bodies and capacitance feel more comfortablewhen they talk in terms of charge than in terms of electric potential in a similarway to the first explanations of the early electric theories. 相似文献
37.
In two experiments, rats were given intermixed or blocked preexposure to two similar compound stimuli, AX and BX. Following preexposure, conditioning trials took place in which AX (Experiment 1) or a novel compound stimulus NX (Experiment 2) was paired with a food-unconditioned stimulus in an appetitive Pavlovian preparation. Animals that were given alternated preexposure showed lower generalization from AX to BX (Experiment 1) and from NX to a new compound, ZX (Experiment 2), than animals that were given blocked preexposure, a perceptual learning and a perceptual learning transfer effect, respectively. 相似文献
38.
PhD graduates hold the highest education degree, are trained to conduct research and can be considered a key element in the
creation, commercialization and diffusion of innovations. The impact of PhDs on innovation and economic development takes
place through several channels such as the accumulation of scientific capital stock, the enhancement of technology transfers
and the promotion of cooperation relationships in innovation processes. Although the placement of PhDs in industry provides
a very important mechanism for transmitting knowledge from universities to firms, information about the characteristics of
the firms that employ PhDs is very scarce. The goal of this paper is to improve understanding of the determinants of the demand
for PhDs in the private sector. Three main potential determinants of the demand for PhDs are considered: cooperation between
firms and universities, R&D activities of firms and several characteristics of firms, size, sector, productivity and age.
The results from the econometric analysis show that cooperation between firms and universities encourages firms to recruit
PhDs and point to the existence of accumulative effects in the hiring of PhD graduates. 相似文献
39.
Concerns regarding whether a sufficient supply of school psychologists exists have been evident for decades. Studies have predicted that school psychology would face a critical personnel shortage that would peak in 2010, but continue into the foreseeable future. The current study is a 10‐year follow‐up investigation based on previously published personnel shortage projections. Data derived from the National Association of School Psychologists 2009–2010 national study were used to examine current personnel shortages as well as to project the extent to which personnel shortages are likely to continue. Findings indicate that the field of school psychology continues to experience a personnel shortage that will continue through 2025. Additionally, greater rates of retirements are projected for the field for school psychologists who are males, who possess a doctoral degree, and for university faculty. Analyses based on the U.S. Census Regions indicate that notable differences are likely to occur in the match between the supply of and demand for school psychologists based on geographical location. Implications are discussed relating to the recruitment and retention of school psychologists and to the services they deliver. 相似文献
40.
Crowdsourcing interactions: using crowdsourcing for evaluating interactive information retrieval systems 总被引:1,自引:0,他引:1
Guido Zuccon Teerapong Leelanupab Stewart Whiting Emine Yilmaz Joemon M. Jose Leif Azzopardi 《Information Retrieval》2013,16(2):267-305
In the field of information retrieval (IR), researchers and practitioners are often faced with a demand for valid approaches to evaluate the performance of retrieval systems. The Cranfield experiment paradigm has been dominant for the in-vitro evaluation of IR systems. Alternative to this paradigm, laboratory-based user studies have been widely used to evaluate interactive information retrieval (IIR) systems, and at the same time investigate users’ information searching behaviours. Major drawbacks of laboratory-based user studies for evaluating IIR systems include the high monetary and temporal costs involved in setting up and running those experiments, the lack of heterogeneity amongst the user population and the limited scale of the experiments, which usually involve a relatively restricted set of users. In this paper, we propose an alternative experimental methodology to laboratory-based user studies. Our novel experimental methodology uses a crowdsourcing platform as a means of engaging study participants. Through crowdsourcing, our experimental methodology can capture user interactions and searching behaviours at a lower cost, with more data, and within a shorter period than traditional laboratory-based user studies, and therefore can be used to assess the performances of IIR systems. In this article, we show the characteristic differences of our approach with respect to traditional IIR experimental and evaluation procedures. We also perform a use case study comparing crowdsourcing-based evaluation with laboratory-based evaluation of IIR systems, which can serve as a tutorial for setting up crowdsourcing-based IIR evaluations. 相似文献