The purpose of this paper is to extract features from vibration signals measured from motors subjected to accelerated bearing fluting aging and to detect the effects of bearing fluting at each aging cycle of induction motors. This trending of bearing degradation is achieved by monitoring the changes in the vibration signals at various sub-band levels. This is accomplished by the application of wavelet transforms and multi-resolution analysis in order to extract information from selected frequency bands with minimum signal distortion. 相似文献
The purpose of this study was to investigate the extent to which professional development predicts principals’ instructional leadership in order to identify whether a relationship exists between the duration of principals’ participation in distinct professional development activities and their perceived practice of instructional leadership while controlling for several principal and school characteristics. The data employed in this study came from the 2013 teaching and learning international survey, which was conducted by the organisation for economic co-operation and development. Four multivariate regression models with the country-controlled dummy variable were implemented in the analysis of the data. The results indicated that the more principals take part in contemporary professional development activities such as professional networking, mentoring and research activities, the more often they engage in instructional leadership practices. However, no relationship between more traditional types of professional development activities, such as courses, conferences, and observational visits, and principals’ instructional leadership, was found. The results have substantial implications for policy-makers and practitioners worldwide, suggesting that any professional development designed to get principles involved in more instructional leadership practices should be based on the contemporary type of professional development activities. 相似文献
This study explored the influence of university-based teacher education courses on preservice teachers as they engaged in the field-based portion of their preparation. Forty-two preservice teachers contributed reflective writings about the successes and challenges they faced during field experiences in light of knowledge and skills learned during their university-based coursework. Participants’ self-reflective writings were coded and analyzed for emerging themes that cut across all responses. The results indicated a shift from concerns about performance of teaching tasks in the classroom to concerns about the performance of students in terms of learning. This shift was consistent with a goal of the preservice program, namely, helping preservice teachers focus on student learning. 相似文献
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
This introduction to the special issue summarizes and contextualizes six novel research contributions at the intersection of information retrieval (IR) and crowdsourcing (also overlapping crowdsourcing’s closely-related sibling, human computation). Several of the papers included in this special issue represent deeper investigations into research topics for which earlier stages of the authors’ research were disseminated at crowdsourcing workshops at SIGIR and WSDM conferences, as well as at the NIST TREC conference. Since the first proposed use of crowdsourcing for IR in 2008, interest in this area has quickly accelerated and led to three workshops, an ongoing NIST TREC track, and a great variety of published papers, talks, and tutorials. We briefly summarize the area in order to help situate the contributions appearing in this special issue. We also discuss some broader current trends and issues in crowdsourcing which bear upon its use in IR and other fields. 相似文献
The study aimed to test the validity and reliability of the Very Short form of the Physical Self-Inventory (PSI-VS) among a sample of 635 Turkish adolescents. These adolescents have completed the 12 original items of the PSI-VS, plus a positively worded reformulation of the single reverse-keyed item of the physical attractiveness subscale. A series of confirmatory factor analyses was used to examine the psychometric properties of the original and modified versions of the PSI-VS. Findings revealed superior psychometric properties with the modified version than with the original set of items. The modified version was thus subsequently used to examine its factor structure invariance across sexes, age groups and sport practice involvement. Results not only report that this version was fully invariant across, but also that latent means were significantly different across sexes and sport practice involvement. In sum, the Turkish modified version of the PSI-VS presents acceptable psychometric properties and may be used to repeatedly and/or intensively assess participants’ physical self-perceptions in the context of sport and exercise interventions. 相似文献
Background: One of the most important goals of science education is to enable students to understand the nature of science (NOS). However, generally regular science teaching in classrooms does not help students improve informed NOS views.
Purpose: This study investigated the influence of an explicit reflective conceptual change approach compared with an explicit reflective inquiry-oriented approach on seventh graders’ understanding of NOS.
Sample: The research was conducted with seventh grade students. A total of 44 students participated in the study.
Design and method: The study was an interpretive study because this study focused on the meanings that students attach to target aspects of NOS. Participants were divided into two groups, each consisting of 22 students. One of the groups learned NOS with an explicit reflective conceptual change approach. The requirements of conceptual change were provided through the use of conceptual change texts and concept cartoons. The other group learned NOS with an explicit reflective inquiry-oriented approach. The data were collected through open-ended questionnaires and semi-structured interviews. These instruments were employed in a pre-test, a post-test and a delayed test. Students’ views of the aspects of NOS were categorized as naive, transitional and informed.
Results: The result of this study indicated that before receiving instruction, most of the participants had transitional views of the tentative, empirical and imaginative and creative aspects of the NOS, and they had naive understandings of the distinction between observation and inference. The instruction in the experimental group led to a 60% – a 25% increase in the number of students who possessed an informed understanding of the tentative, empirical, creative and observation and inference aspect of the NOS. The instruction in the control group led to a 30% – a 15% increase in the informed NOS views.
Conclusion: The explicit reflective conceptual change approach is more effective than the explicit reflective inquiry-oriented approach in improving participants’ NOS conceptions. Another conclusion of this study is that if NOS is taught within the explicit reflective conceptual change approach, learners can retain learned views long after instruction. 相似文献
